List of Colloquium

[274] Topic: Variations in the intensity of Ca-K plages and networks with solar cycle phase

Speaker: Prof. Jagdev Singh
Affiliation: IIA, Bangalore
Date (yyyy-mm-dd): 2017-08-18
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: We discussed the details of observations and methodology adopted to analyse the Ca-K spectrohelio-grams obtained at Kodaikanal observatory (KKL) during the period of 1905 - 2005. We have given the derived values of threshold of the intensity contrast to detect the various Ca-K line features such as plages and networks. Using this procedure we have studied the variation of Ca-K plage areas, enhanced network (EN) and active network (AN). We have derived the areas of all the three features for all the data available at Kodaikanal observatory to study the long term variations on the sun. Further, we have investigated the variation of intensity contrast of these features with time with the temporal resolution of 3 months assuming the quiet chromosphere remains unchanged during the period of 1906 - 2005 and found that average intensity of plages, EN and AN varies with solar cycle phase being less during the minimum phase. In addition, the average intensity of plages varies with a long period being maximum during the solar cycle number 19 (strongest solar cycle during the 20th century). The correlation between intensity of the Ca-K emission and strength of the magnetic field suggests that the magnitude of the magnetic field is also related with sunspot number and plage area of a solar cycle. It may be noted that the variation of intensity of networks with time has been studied for the first time.


About Speaker: Prof. Jagdev Singh has long association with ARIES earlier UPSO, since 1988 when the planning and execution for the first astronomical expedition to Antractica was started. Lead the first astronomical expedition, 3 member team consisting to Indian station in Antarctica in 1989. 1.He did his Ph. D. With Dr. M K V Vainu Bappu a well known astronomer in the year 1984 using the data obtained by him during the total solar eclipses in 1980 & 1983. 2.Planned and successfully executed 10 expeditions to make observations of the solar corona during the total solar eclipses of the Sun. 3. He planned, designed and proposed VELC mission on ADITYA-1 (first Indian mission (Solar Coronagraph) to observe the sun) expected to be launched in 2019 (Principal Investigator from 2006 to 2015).


[273] Topic: Introduction to solar observational facilities

Speaker: Prof. Jagdev Singh
Affiliation: IIA, Bangalore
Date (yyyy-mm-dd): 2017-08-17
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: In this talk I about the observational facilities used in the past to take the images of the sun in continuum and some prominent absorption line such as H-alpha and Ca-K. Their development with time. Then I discuss ground base high spatial and spectral resolution recent facilities in operation now a days. The space base instruments operating in the UV, EUV and X-rays are also explained in brief. Then I describe the future ground base and space base facilities such as 4m solar telescope ,DKIST ; space base coronagraph ADITYA-1 in brief. This talk is also preliminary in nature.


About Speaker: Prof. Jagdev Singh has long association with ARIES earlier UPSO, since 1988 when the planning and execution for the first astronomical expedition to Antractica was started. Lead the first astronomical expedition, 3 member team consisting to Indian station in Antarctica in 1989. 1.He did his Ph. D. With Dr. M K V Vainu Bappu a well known astronomer in the year 1984 using the data obtained by him during the total solar eclipses in 1980 & 1983. 2.Planned and successfully executed 10 expeditions to make observations of the solar corona during the total solar eclipses of the Sun. 3. He planned, designed and proposed VELC mission on ADITYA-1 (first Indian mission (Solar Coronagraph) to observe the sun) expected to be launched in 2019 (Principal Investigator from 2006 to 2015).


[272] Topic: The Sun and its structure.

Speaker: Prof. Jagdev Singh
Affiliation: IIA, Bangalore
Date (yyyy-mm-dd): 2017-08-16
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: In this talk I describe the physical properties of the sun and energy generation in brief. Then I talk about the various surface features such as granules, super-granules, sunspots and activities that follows the sunspots. I also describe the chromosphere, coronal features and explosive events in brief. Then I discuss the sunspot and magnetic cycle. The talk is of preliminary in nature.


About Speaker: Prof. Jagdev Singh has long association with ARIES earlier UPSO, since 1988 when the planning and execution for the first astronomical expedition to Antractica was started. Lead the first astronomical expedition, 3 member team consisting to Indian station in Antarctica in 1989. 1.He did his Ph. D. With Dr. M K V Vainu Bappu a well known astronomer in the year 1984 using the data obtained by him during the total solar eclipses in 1980 & 1983. 2.Planned and successfully executed 10 expeditions to make observations of the solar corona during the total solar eclipses of the Sun. 3. He planned, designed and proposed VELC mission on ADITYA-1 (first Indian mission (Solar Coronagraph) to observe the sun) expected to be launched in 2019 (Principal Investigator from 2006 to 2015).


[271] Topic: First Antarctica Expedition to observe the sun at mid-night

Speaker: Prof. Jagdev singh
Affiliation: IIA, Bangalore
Date (yyyy-mm-dd): 2017-08-14
Time: 15:30hr
Venue: ARIES AUDITORIUM

Abstract: The large convective cells have an average size of about 30000 Km and average life of about 20 hours. These can also be seen as network cells in the Ca-K line images of the sun. Therefore, to study the formation and decay of these cells without the occurrences of day-night cycle, we planned imaging of sun in Ca-K line with an interval of about 5 minutes. We, were lucky, to get the images for 106 hours. Generally, the weather condition in Antarctic region remain very hostile and sky remains clear for a day or two. In my talk I discuss the various aspects of the expedition and the results obtained from the analysis of data. We find that the convective cells in the active region have larger life time as compared to similar size cells in the quiet region of the sun. It implies that the presence of magnetic field slows down the diffusion rate. It may be noted that the opportunity exited starting from the first Indian expedition to Antarctic region but it materialized only in the ninth Indian expedition to Antarctica.


About Speaker: Prof. Jagdev Singh has long association with ARIES earlier UPSO, since 1988 when the planning and execution for the first astronomical expedition to Antractica was started. Lead the first astronomical expedition, 3 member team consisting to Indian station in Antarctica in 1989. 1.He did his Ph. D. With Dr. M K V Vainu Bappu a well known astronomer in the year 1984 using the data obtained by him during the total solar eclipses in 1980 & 1983. 2.Planned and successfully executed 10 expeditions to make observations of the solar corona during the total solar eclipses of the Sun. 3. He planned, designed and proposed VELC mission on ADITYA-1 (first Indian mission (Solar Coronagraph) to observe the sun) expected to be launched in 2019 (Principal Investigator from 2006 to 2015).


[260] Topic: Comets - a prob to explore early solar nebula

Speaker: Prof. U. C. Joshi
Affiliation: Physical Research Laboratory, Ahmedabad
Date (yyyy-mm-dd): 2017-05-25
Time: 15:30hr
Venue: ARIES, Auditorium

Abstract: Cometary bodies are located in the farthest region of the solar system, hence least weathered and thus possess pristine material. At some instance these bodies are deected toward the inner region of solar system and make glorious appearance in the sky. Cometary material is mixture of dust and ices and the physical conditions and chemical composition of early solar nebula in imprinted on it. On approaching closer to the Sun ices get sublimated and ejected out of the nucleus forming coma. Remote observations from ground based observatories allow us to study the constituents of the coma. Study of cometary dust and gas is of great importance to investigate physical conditions and chemical make up that existed in the beginning of the formation of solar system. The talk will cover a brief introduction and importance of comets and some of the recent results will be discussed.


About Speaker: Visiting Professor


[250] Topic: 21-cm Cosmology

Speaker: Prof. Somnath Bharadwaj
Affiliation: IIT Kharagpur
Date (yyyy-mm-dd): 2017-05-15
Time: 15:30hr
Venue: ARIES auditorium

Abstract: The redshifted 21-cm cm line from neutral Hydrogen provides an unique tool for studying the Universe. This radiation appears as a faint background in low frequency radio observations and the measurement of the fluctuations in this background radiation potentially allow us to study the large scale structures in Universe over a very broad range of redshifts. The measurement of this radiation also hold the potential of allowing us to probe the formation of the first galaxies which are believed to have re-ionised the universe. This talk will start with a broad overview of this topic and then present some of the recent research.


About Speaker: Somnath Bharadwaj is Professor of Physics at IIT Kharagpur. His group work in the areas of Astrophysics and Cosmology. His research is currently focused on using low frequency radio telescopes to study the high redshift universe using the redshifted 21-cm radiation from neutral hydrogen. Group is involved in theoretical, computational and also on observational work connected to this issue. (see Prof. Somnath on-line detail pedagogical lecture in astronomy at: http://www.nptelvideos.in/2012/11/ especially on astrophysics & cosmology , also available on utube)


[254] Topic: KOI HAI ? BRAHMAAND MEIN JEEVAN (Is anyone? Life in the Universe)

Speaker: Dr. C. M. Nautiyal
Affiliation: At present:Chairman, young Scientists Project scheme, UP govt., Retd. Scientist:
Date (yyyy-mm-dd): 2017-05-01
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: Life began on Earth 3.8 billion years ago as a consequence of many coincidences of astronomical, chemical and circumstantial nature. Having taken off from a simple single form of life, it has reached the present complexity of human mind that strives to explore extra-terrestrial abodes of life. In the universe comprising of trillions of galaxies, each of hundreds of billions or more stars,it doesnt appear logical to believe that Earth is the only cradle of life. But the truth remains that we have not seen any evidence of extra-terrestrial life. In this popular level talk, an attempt will be made to explore proper abodes of life outside Earth. Organic material in meteorites, strange bacteria in the depths of Mediterranean Sea and survival of life in unexpected places of extreme conditions seem to shatter our concept about normal life. The results from the recent planetary missions of NASA, ESA and other countries indicate that we may be on the brink of discovery of something new.


About Speaker: At present, he is Chairman, Young Scientists’ project scheme of UP Govt.; Member, Board of Studies, CCS Meerut University; and continuing as coordinator of the Rock Art Documentation Committee for UP and the outstation member of Vigyan Parishad, Prayag. Formerly, Scientist-F, at BSIP (DST) Lucknow.


[247] Topic: Cold Gas at High Redshift

Speaker: Nissim Kanekar
Affiliation: NCRA-TIFR
Date (yyyy-mm-dd): 2017-03-27
Time: 15:30hr
Venue: Auditorium

Abstract: The gas and dynamical masses of damped Lyman-alpha absorbers (DLAs) have been open questions in the field of galaxy evolution for more than three decades. This talk will describe new results from Arecibo and ALMA searches for HI 21cm, CO and CII-158 micron searches emission from a sample of DLAs at, respectively, low (z < 0.1), intermediate (z~0.7) and high (z~4) redshifts. Our HI 21cm observations of the DLAs at z<0.1 yield normal gas masses, <~ 5 x 10^9 solar masses, but very high gas-to-stars mass ratios, ~ 5-100, far higher than in normal galaxies. For the absorbers at intermediate redshifts, we obtain large molecular gas masses in the six systems with CO detections, despite their low optical star formation rates. We also obtain high star formation rates (based on dust continuum emission) and high CII-158 micron line luminosities for the DLA host galaxies at z~4. For the CO and CII-158 micron detections, the impact parameters of the host galaxies are high, 15-45 kpc, far larger than expected based on earlier studies. These are the first CO and CII-158 micron detections in DLA hosts, providing a new window on physical conditions in the absorbers and yielding a new tool to identify DLA host galaxies at high redshifts.


About Speaker: Dr. Nissim Kanekar is a faculty with NCRA-TIFR


[245] Topic: High Power VHF Radar Studies of Earth Atmosphere and Ionosphere

Speaker: Prof P B Rao
Affiliation: National Remote Sensing Centre
Date (yyyy-mm-dd): 2017-02-20
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: High power phase coherent radars at VHF opened up opportunities to explore the earth’s atmosphere and ionosphere with unprecedented spatial and temporal resolutions. The application of the 50 MHz Jicamarca radar, built originally for coherent and incoherent backscatter studies of the ionosphere, to probe the structure and dynamics of the middle atmosphere has led to what is now referred to as MST (Mesosphere-Stratosphere-Troposphere) radar technique. The basic theory for the high power VHF radar backscatter mechanisms, radar technique, signal and data processing methods for parameter retrieval and an overview of the scientific results from high resolution studies of atmospheric structure and dynamics and ionospheric plasma irregularities carried out using MST radar at Gadanki are presented.


About Speaker: Prof P B Rao is an renowned expert in the field of high power VHF radars. Earlier, he served as a Director, National atmospheric research laboratory during 1990-1998. Prof Rao is presently serving as visiting professor (Honorary) in National remote sensing centre, Dept. of Space, Hyderabad.


[243] Topic: Fascinating Life-stories of Pulsars

Speaker: Avinash Deshpande
Affiliation: RRI, Bangalore
Date (yyyy-mm-dd): 2016-12-06
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: Pulsars are believed to be strongly magnetized, fast rotating neutron stars, with over 2000 discovered in our Galaxy so far. In the long march towards the elucidation of the mysterious ways of pulsars, a few special ones have taught us more than most of the rest put together. Apart from sharing our understanding of the origin and evolution of these cosmic light-houses,the talk will try to highlight a few illustrious members of the pulsar family, and focus on some of the key messages they bring to us.


About Speaker: Works at Raman Research Institute, Bangalore, in their Astronomy & Astrophysics group, since 1980. An electrical engineer by training(BTech 1980 IIT Kanpur; PhD 1988 IIT Bombay).Primarily engaged in radio astronomy activities.Signal and image processing, instrumentation,and understanding noise & uncertainties are his interests. He has been trying to learn about these issues in the context of pulsars, interstellar medium and radio interferometry.


[241] Topic: Introduction of our recent activities to improve methane emission estimate over South Asia-AMASA Project

Speaker: Prof Sachiko Hayashida
Affiliation: Nara Womens University, Nara
Date (yyyy-mm-dd): 2016-11-17
Time: 11:30hr
Venue: Council Room, Ashiwni Guest House

Abstract: Methane (CH4) is the second most significant anthropogenic greenhouse gas. Most of methane emissions from Asia are attributable to ruminant animals and rice fields, but the quantitative estimate of methane emissions remains highly uncertain.This has led to initiation of a project, called Atmospheric Methane from Agriculture in South Asia (AMASA), to study methane emission estimate from South Asia. This project is supported by Ministry of Environment, Japan. The first goal of the project is to downscale the emission estimate from a global scale into a regional scale and improve methane emission estimate from South Asia by using GOSAT and ground-based data. To accomplish this goal, we are now collaborating with many local scientists and farmers to carry out in-situ measurements in India and Bangladesh. The second goal is to develop some emission mitigation proposals. In this project, we are focusing on methane emission from rice fields. One approach to reduce methane emission from rice fields is an intermittent draining of water, and another approach is a proper fertilizer management. Based on local experimental works on those measures, we will arrange some mitigation scenarios, and input them into an atmospheric transport model to examine if it is realizable or detectable.


About Speaker: Prof Sachiko Hayashida is leading scientist at Nara Women University, Nara. Her research interest is mainly on ground based and space-borne observations.


[240] Topic: Air Quality in the "Anthropocene" Era- a Satellite Perspective

Speaker: Dr Pawan K Bhartia
Affiliation: NASA Goddard Space Flight Center
Date (yyyy-mm-dd): 2016-11-04
Time: 15:30hr
Venue: Auditorium

Abstract: Chemistry Nobel Laureate Paul Crutzen has coined the term “anthropocene” to put the modern industrial era in the geological context to highlight the fact that human-induced changes to the earth are in some cases as large as the changes that occurred in geological times. Though the changes in the terra firma and the biosphere are the most visible manifestations of these changes, the quality of our life-sustaining atmosphere is also changing rapidly. Air quality is affected not only by the “bad air” that we can smell or feel in our lungs but also by the change in the composition of the “good air” that has made life on this planet possible. The most well known of these changes has been the rapid thinning of the ozone layer in the polar regions, popularly known as the Ozone Hole. Satellite images of this phenomenon captured the attention of the world in the mid 80s leading to rapid phase-out of the offending chemicals. Examples of bad air are gases and particulate matter near the surface. I will discuss how modern satellite instruments are tracking them to help the policy makers in tracking appropriate actions.


About Speaker: Dr. Pawan Kumar Bhartia is a Senior Research Scientist at NASA Goddard Space Flight Center, Greenbelt, Maryland, USA. He is an internationally known expert on ultraviolet remote sensing of Earth from space. He led the TOMS Project from 1991 to 2005, which received the William T. Pecora award in 2006, for creating unique long-term datasets from TOMS. He led the Aura/OMI US science team from 2004 to 2011 and currently leads the team that is producing stratospheric ozone and aerosol profiles from the OMPS-limb instrument on the Suomi NPP satellite. He served as the Head of the Atmospheric Chemistry Branch at NASA GSFC from 1994 to 2006. He was elected to the International Ozone Commission in 2008. He is the recipient of William Nordberg medal and Robert H. Goddard Award of Merit from NASA GSFC, Outstanding Leadership and the Distinguished Service Medals from NASA, and the Remote Sensing Prize from the American Meteorological Society. He received Ph. D. in Physics and M.S. in Computer Science from Purdue University, Lafayette, Indiana, and B.Sc (Hon) and M. Sc from Patna University, Patna, India.


[237] Topic: Kelvin-Helmholtz instability in rotating magnetized solar atmospheric jets

Speaker: Prof Ivan Zhelyazkov
Affiliation: Kelvin-Helmholtz instability in rotating magnetized solar atmospheric jets Ivan
Date (yyyy-mm-dd): 2016-09-22
Time: 15:30hr
Venue: Auditorium

Abstract: We study the conditions under which spinning twisted solar jets observed by Solar Dynamic Observatory (SDO) can become unstable against the Kelvin-Helmholtz (KH) instability. The KH instability arises at the interface of two fluid layers that move with different speeds. Flows are generally uniform in the two layers, however, a strong velocity shear arises near the interface region of these two fluids forming a vortex sheet that become unstable to the spirale-like perturbations. When a magnetic flux tube moves along its axis, a vortex sheet is evolved near tube's boundary which may become unstable against to the KH instability provided that its axial velocity exceeds some critical value. This vortex sheet causes the conversion of the directed flow energy into a turbulent energy.


About Speaker: Prof. Ivan Zhelyazkov is a senior Professor at Faculty of Physics, Sofia University and PI of the Indo—Bulgarian project from Bulgarian side. He is working in the Kelvin-Helmholtz in the solar atmosphere. He has published several research papers in the international journal of repute. He is visiting for here under the Indo-Bulgarian exchange program.


[232] Topic: Accuracy of Upper Tropospheric Humidity Measurements and Present Balloon Measurements in Nainital, India

Speaker: Prof Thomas Peter
Affiliation: Institute for Atmospheric and Climate Science, ETH, Zurich
Date (yyyy-mm-dd): 2016-08-19
Time: 15:30hr
Venue: Auditorium

Abstract: Owing its role as “gateway” to the global stratosphere, knowledge of the tropical tropopause layer with respect to its water budget is important in order to understand the radiative and chemical properties not only of this layer itself, but of the entire stratosphere, including its impact on global climate. Previous measurements suggest that these measurements are very difficult, and no accepted instrumental “gold standard” exists. In particular, instrumental uncertainties have prevented to properly judge to which degree observed persistent extremely high saturation ratios over ice (RHice >> 1.5) within cirrus clouds are real or only an instrumental artifact. Here we show that humidity measurements within cirrus clouds allow to estimate the measurement uncertainty of each instrument, owing to the restoring force that the ice surfaces have on the H2O in the gas phase. The measurements of most instruments can be explained as superposition of this restoring force and small-scale temperature fluctuations, allowing to explain even data points with extreme super‐ or subsaturation. In general, this demonstrates progress in measurement technology applicable to the adverse conditions of the tropical tropopause layer. On the other hand, this analysis makes clear that future improvements in our quantitative understanding of the freeze‐drying process will only be possible if the remaining measurement uncertainties of RHice of ca. 20% can be overcome. Finally, I will confront this analysis with some results from the ballooning activities presently ongoing here in Nainital.


About Speaker: Thomas Peter has been Full Professor for Atmospheric Chemistry at the Institute for Atmospheric and Climate Science since January 1999. Before this, he was leader of the group for heterogeneous chemistry and microphysics of atmospheric aerosols at Max Planck Institute for Chemistry in Mainz. Presently, he is visiting ARIES, Nainital.


[227] Topic: Atmospheric bioaerosols in the Earth System: Climate and ecosystem interaction in Indian perspective

Speaker: Dr Sachin Gunthe
Affiliation: IIT Madras ( Chennai)
Date (yyyy-mm-dd): 2016-07-28
Time: 15:30hr
Venue: Auditorium

Abstract: Atmospheric aerosols of biological origin are ubiquitous in the Earth’s atmosphere and play an important role in Erath’s climate and ecosystem health. These bioaerosols mainly include airborne bacteria, fungal spores, pollens, plant and animal fragments, etc. These bioaerosols are essential for reproduction and spread of organisms across various ecosystems by means of air dispersal. During dispersal, however, they can cause or enhance human, plant, and animal diseases. Moreover, they can also serve as nuclei for cloud droplets and ice crystal thus affecting the hydrological cycle. The abundance, diversity, and implications of bioserosols on climate and ecosystem health, however, is not well characterized and leaves a wide gap in the scientific understanding of their interactions with climate and ecosystem. Over the Indian region, which has a diverse land-use pattern and experiences the contrasting synoptic scale weather phenomenon by means of Southwest and Northeast monsoon, the characteristic source properties of bioaerosols and their impact on climate and human health exhibit manifold implications. I will present the novel bioaerosol measurements carried out over Indian region at contrasting locations during distinct seasons using advanced state-of-the-art techniques.


About Speaker: Dr Gunthe is Assistant Professor and Head Max Planck Partner Group at IIT Madras, Department of civil Engineering,IIT Madras.


[218] Topic: Development of On-chip Photonic Instruments for Astronomical Spectroscopy

Speaker: Pradip Gatkine
Affiliation: University of Maryland at College Park, USA
Date (yyyy-mm-dd): 2016-07-07
Time: 15:30hr
Venue: Auditorium

Abstract: The next-generation of ground-based extremely large telescopes (ELTs) in optical and NIR will have diameters in the range of thirty meters (such as TMT). The volume, mass, and cost of the instrument scale roughly as diameter cubed. This necessitates the development of suitable seeing limited spectroscopic instrumentation. Astrophotonics is the next-generation approach that provides the means to miniaturize near-infrared (NIR) spectrometers for upcoming large telescopes and make them more robust and inexpensive. Arrayed waveguide gratings (AWG) is one such technology suitable for astronomical spectroscopy. We have developed on-chip AWG spectrographs in H-band of near-infrared suitable for astronomical applications. We have also simulated Fiber Bragg Grating (FBG) based OH-emission suppression in NIR (H band and J band) for observing high redshift (6-12) GRB afterglows. I will summarize our recent work on these astrophotonic technologies (AWG and Bragg Gratings) and their broad implications to astronomy. Astrophotonics has a potential to be a paradigm-shifting development for future ground-, balloon- and space-based telescopes.


About Speaker: Astronomy graduate student at University of Maryland at College Park, USA


[217] Topic: Intriguing aspects of Atmospheric Waves over the Himalayan region as revealed by ground based and satellite observations

Speaker: Dr K Niranjan Kumar
Affiliation: University of Tokyo
Date (yyyy-mm-dd): 2016-06-30
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: In this talk, my focus will be mainly on the atmospheric waves and mesoscale dynamics with special emphasis on surrounding deep convection, Himalayan Mountains, and the jet streams. The properties of atmospheric waves, their sources and their many effects in the atmosphere are studied using the various observational techniques includes Satellite remote sensing (AIRS, CALIPSO, MLS), balloon-borne radiosonde observations along with global model reanalysis data sets such as ECMWF, NCEP/NCAR, MERRA etc. The three-dimensional properties of atmospheric gravity waves are important in estimating momentum flux. Also, the parameterization schemes used in the global circulation models (GCMs) are still based on simplifying assumptions and estimates of momentum flux is still rely on models than on measurements. To estimate the gravity wave momentum flux it is required to obtain the simultaneous measurement of horizontal and vertical. Hence, in order to achieve this, we have used some innovative techniques using the advanced space-borne measurements such as Atmospheric Infrared Sounder (AIRS), to image the gravity waves in three dimensions and hence estimated the momentum flux over the Himalayan Mountains. Further, my recent focus is on the dynamics of heavy rainfall events over the central Himalayan region and will share some preliminary and interesting observations for which the detailed analysis is still under progress. In this context, I will also like to discuss about the predictability of extreme weather over the Uttarakhand and adjoining mountainous regions through the response of the upper tropospheric Rossby waves and synoptic-scale circulations.


About Speaker: Dr Niranjan Kumar is expert in lower and upper atmospheric wave dynamics with special emphasis on the extreme rainfall events over local, regional and global scales.


[209] Topic: Assessment of carbonaceous aerosols over northern part of India: Mass level and its impact on regional climate

Speaker: Dr Suresh Tiwari
Affiliation: Indian Institute of Tropical Meteorology, New Delhi Branch
Date (yyyy-mm-dd): 2016-06-22
Time: 15:30hr
Venue: Auditorium

Abstract: Carbonaceous aerosols, (organic carbon: OC and black carbon/elemental carbon: BC/EC) constitute a significant fraction (∼10–70%) of the fine mode particles (PM2.5: particle cut-off diameters d ≤ 2.5 μm) have gain significant importance in aerosol research due to adverse effects on human health, environmental issues as visibility impairment, regional air pollution, etc. and are emitted into the atmosphere together by open biomass burning, indoor biomass/biofuel combustion for cooking and heating, and fossil fuels combustion. OC, is a cooling agent (a scattering particle), is emitted both as primary aerosols and as volatile organic gases that are subsequently converted to the secondary organic aerosols, however, BC, a climate-warming agent (an absorbing particle) is mostly emitted into the atmosphere from primary sources. Indo-Gangetic plains (IGP) which is one of the highly populated and polluted region in the world due to a higher loading of atmospheric aerosols produced by both natural as well as anthropogenic sources, is located in the northern part of India. Recent studies indicated that the level of PM2.5 over IGP region is greater than 120 µgm-3 (annual mean) which is 3 and 10 times higher than the Indian National Ambient air Quality standard and US-EPA standard respectively. The contribution of carbonaceous aerosols to fine mode particles are ~ 40%. Due to the higher mass concentrations of BC, the mean atmospheric heating rates were observed greater than 2 K day−1 over this region and it would probably galvanize in the strengthening of temperature inversion which further leads to the poor dispersion and affecting the formation of clouds. We have taken several in-situ observations over IGP region of carbonaceous aerosols and found tremendous high concentrations. In details, we will discuss in my presentation. Our study suggests that the serious detrimental impacts on regional climate due to the high concentrations of carbonaceous aerosols and are suggested that the competent authority will take immediate and stringent measures to improve the regional air quality in the northern part of India.


About Speaker: Dr S Tiwari is at Indian Institute of Tropical Meteorology, New Delhi Branch. He is the scientist incharge of the branch. His research interest is on rain water precipitation, aerosol optical, physical and chemical properties and its radiative impact.


[204] Topic: Spatial and Temporal indices of Indian Monsoon Rainfall

Speaker: Dr M S Narayanan
Affiliation: S R M University
Date (yyyy-mm-dd): 2016-06-09
Time: 15:30hr
Venue: Auditorium

Abstract: Indian summer monsoon rainfall (ISMR) has three important attributes for its proper representation – viz total seasonal quantum, its spatial and temporal distribution over the different Indian land mass for the four monsoonal months. Traditionally only the all India area – weighted average rainfall of the season as a whole, has been used as a single index to study the interannual variations and teleconnections with other global parameters. In this study, using 115 years of ISMR gridded data, we have proposed two new indices - the Temporal and the Spatial Indices, besides the Quantum Index (in vogue). These indices for any year depend on the number of Normal rainfall Days and number of Normal rainfall Grids during the year. It is suggested that the incorporating all three indices will be a better way to study the Indian monsoon intra seasonal – inter annual variabilities. Case studies of a few good and poor monsoon years are discussed to highlight the importance of the new indices.


About Speaker: Dr M S Narayanan is at SRM University. He was group director SAC,ISRO,Ahmedabad. His research interest is on satellite remote sensing, with focus on monsoon rainfall.


[203] Topic: Rainfall estimation from Satellites - how far are they from reality ?

Speaker: Dr M S Narayanan
Affiliation: S R M University
Date (yyyy-mm-dd): 2016-06-08
Time: 15:30hr
Venue: Auditorium

Abstract: The recent heavy rainfall events over Chennai on Nov 15 – 16 and on Nov 30 – Dec 1, 2015 have provided an excellent opportunity to inter compare the rainfall estimates from satellites - GPM, INSAT – 3D; Chennai Doppler Radar and ground raingauges. The results show wide disparity between the various estimates, posing the basic question as to the spatio temporal scales at which any one could be a substitute for the other. Our studies to inter compare TRMM merged rainfall products with IMD gridded rainfall over Indian land mass from 15 years of concurrent data, have shown that on daily scale, only beyond 5 x 5 deg spatial average, the two satellite estimates and ground measurements have semblance of compatibility. Details of this study which has been performed for different rain rates will be presented.


About Speaker: Dr M S Narayanan is at SRM University. He was group director SAC,ISRO,Ahmedabad. His research interest is on satellite remote sensing, with focus on monsoon rainfall.


[196] Topic: Cosmic Microwave Background as a Probe of Cosmic Magnetic Fields

Speaker: T. R. Seshadri
Affiliation: Delhi University
Date (yyyy-mm-dd): 2016-06-06
Time: 15:45hr
Venue: Auditorium

Abstract: We still do not have a fully satisfactory theory of the origin of cosmic magnetic fields. Placing constraints of these fields could play an important role in deciding which of the models are likely to be the plausible ones. The polarization and power spectrum of CMBR could be an important probe in this endeavor. The focus of the talk will be to show how the polarization, power spectrum, bispectrum and trispectrum could place constraints on the strength of these fields.


About Speaker: Professor T. R. Sesahdri is a faculty in the Department of Physics and Astrophysics, University of Delhi, Delhi. He works on Cosmology.


[187] Topic: Probing the Universe and fundamental physics with QSOs absorption lines

Speaker: Prof. R. Srianand
Affiliation: IUCAA
Date (yyyy-mm-dd): 2016-05-25
Time: 15:30hr
Venue: ARIES auditorium

Abstract: Absorption lines seen in the spectra of high-z QSOs allow one to probe the cosmology, galaxy formation and its evolution. In particular the detectability of absorption does not depend on the luminosity of the absorbing source, it provides a luminosity unbiased tracer of the universe. In addition to probing cosmological evolution one will be able to place stringent constraints on the variations of fundamental constants. In this talk the author will review the present status of the field and summarize future programmes with TMT.


About Speaker: Prof. Srianand, senior professor at IUCAA, is involved in various observational and theoretical projects: 1) probing the physical conditions in the high-z proto-galaxies traced by DLAs, 2) probing the time and space variation of fundamental constants using very high resolution spectra of QSOs, 3) tracing the redshift evolution of the CMB temperature using fine-structure lines and 4) semi-analytic modelling of formation and evolution of IGM, reionization and redshift evolution of global star formation rate density in the universe.


[185] Topic: A step toward realization of a large Optical-NIR telescope in India

Speaker: DR PADMAKAR S PARIHAR
Affiliation: IIA Bangalore
Date (yyyy-mm-dd): 2016-05-20
Time: 15:30hr
Venue: Auditorium

Abstract: Recently install 3.6m Devasthal Optical Telescope (DOT) and forthcoming Thirty Meter Telescope(TMT) would not be enough to cater the need of growing Indian astronomical community. Access to 10-12m size optical-NIR telescope equipped with state of the art back-end instruments can bridge the gap between DOT and TMT. A telescope of this size is only possible when primary mirror is made of smaller mirror segments. In order to get acquainted with segmented mirror telescope technology, in IIA we have initiated a project to develop a small prototype telescope made of seven spherical mirror segments (PSMT). I will present the progress made in opto-mechanical design as well development of other sub-systems required for the PSMT. The prototyping effort is one step toward realization of a large telescope in India and it is expected to be completed in 2 years period.


About Speaker: Dr. Padmakar is a Associate Professor at IIA, Bangalore and involved in astronomical instrumentation.


[182] Topic: India s MOM [Mars Orbiter Mission]

Speaker: Dr. S M Ahmed
Affiliation: University of Hyderabad
Date (yyyy-mm-dd): 2016-05-17
Time: 15:30hr
Venue: Auditorium

Abstract: The human quest to learn more beyond earth has taken them to moon in the mid-70s; presently there is rush to catch up with the closest planet – MARS, in un raveling secrets of any trace of life on our nearest neighbor. The Indian space craft, Mars Orbiter Mission, MOM reached Mars after travelling a grueling distance of around 60-crore kms from Earth. While reaching the Mars itself had been very tricky with many failed attempts on part of NASA, erstwhile USSR, ESA; with a success rate of around 36% to-date, India became the FIRST country ever, to reach Mars in its first attempt. In the capacity of core science team member of Chandrayaan-I project, the author had first-hand experience in developing an indigenous science payload, CHACE a quadrupole mass spectrometer, as a part of Moon Impact Probe (MIP) mission. The discussion would revolve around the unique features of planet Mars, the challenges faced by the space craft in reaching to its target, quest for measuring the trace gas methane and details of a set 5-instrumntes it carries.


About Speaker: Dr. S. M. Ahmed is heading the Central Instruments Laboratory as Principal Scientific Officer at the University of Hyderabad. Dr. Ahmed obtained his Ph.D. from the Physical Research Laboratory, Ahmedabad. He has worked at IPR, JPL, EPFL, and VSSC. He joined ISRO s most ambitious Chandrayaan project in 2004 and developed a quadrupole based mass spectrometer, CHACE, which worked successfully in the Moon Impact Probe mission.


[178] Topic: Application of VHF radars for monitoring atmospheric structure and dynamics: Gap areas

Speaker: Dr M Venkat Ratnam
Affiliation: National Atmospheric Research Laboratory
Date (yyyy-mm-dd): 2016-05-05
Time: 11:30hr
Venue: ARIES Auditorium

Abstract: VHF radars have evolved as powerful tool for monitoring Earths atmosphere. It has several advantageous over other techniques as they provide observations with high temporal and vertical resolutions. Most advantage is providing 3-D wind fields particularly the vertical wind which made it unique among other techniques. These radars are effectively utilized for basic atmospheric research besides its operational applications (forecasting, aviation, wind support for rocket launches and air quality meteorology). Fundamental research includes boundary layer processes, turbulence, wave dynamics, stability of the atmosphere, retrieval of temperature and humidity, tropical tropopause layer characteristics, stratosphere -troposphere exchange processes, Indian summer monsoon dynamics (low level jet, tropical easterly jet, monsoon circulation), Hadley circulation, mesospheric and ionospheric dynamics, lower, middle and upper atmosphere coupling processes. Present talk summarizes all these applications. It also covers identification of few gap areas while using network of such radars (existing and upcoming) and adding complementary techniques.


About Speaker: Dr M Venkat Ratnam is Scientist-F in Atmospheric structure and Dynamics Group, National Atmospheric Research Laboratory, Gadanki, ISRO, Department of Space. He is an expert in Lower and Upper Atmospheric Dynamics. He has been actively involved in several national and international campaigns (CAWSES etc).


[169] Topic: Ozone and Atmospheric Transport

Speaker: David W Tarasick
Affiliation: Evironmental and Climate Change Canada
Date (yyyy-mm-dd): 2016-01-29
Time: 15:30hr
Venue: Auditorium

Abstract: Ozone has been studied since the 1930s, in large part because of its properties as a tracer of atmospheric motion. Although recent interest in ozone focuses on its importance as an absorber of UV and IR radiation (and thereby an important greenhouse gas), and as a tropospheric oxidant and pollutant, the relatively long chemical lifetime of ozone in both the stratosphere and the troposphere means that transport is as important as chemistry to understanding the past and present, and predicting the future distribution of ozone in the atmosphere. In Canada routine measurements of the vertical profile of ozone concentration using balloon-borne ozonesondes have been carried at Resolute Bay since 1966, making this record the longest in the world. Ozonesondes are currently flown weekly at eight sites, making the Canadian network also one of the largest in the world, and particularly important for studies of ozone changes over the past half-century. Since its early use in the 1970s, atmospheric Lagrangian transport (trajectory) modeling, driven by increasingly sophisticated and accurate numerical weather prediction models, has become a powerful tool for studying the transport of atmospheric tracers like ozone. Although these data are sparse both in space and time, they have high vertical resolution, and can be extended by trajectory mapping to other locations and times. This is possible because the lifetime of ozone is of the order of weeks in the troposphere, and months or more in the stratosphere. This widely available technique has numerous applications to the study of ozone processes, and has been essential to current understanding of Arctic ozone depletion, and stratosphere-troposphere exchange. Recent uses of trajectory mapping in ozone data assimilation and in ozone source attribution will also be shown. A recent application of trajectory mapping to the entire global ozonesonde dataset has produced a unique three-dimensional global ozone dataset from the late 1960s to the present day. Although developed initially as climatology for use as an a priori for models and for satellite retrievals, the dataset can also be used for the study of regional and global ozone trends, stratosphere-troposphere relationships, and the regional representativeness of individual sounding sites.


About Speaker: Prof. David W. Tarasick (Evironmental and Climate Change Canada, Ontario, Canada) is responsible for Canadian Ozonesonde Network, which is the largest network in world with a site of longest record (since 1966) of observations. He is co-inventor of UV Index (1992). He has chaired different scientific program on ozone and also SSC member of TOAR (Tropospheric Ozone Assessment Report). He is involved in different international campaign e.g. (BORTAS, IONS, ARCTAS, etc).


[166] Topic: Global Nanotechnology Research for Healthcare

Speaker: Dr Anil Patri
Affiliation: US FDA
Date (yyyy-mm-dd): 2015-12-28
Time: 15:30hr
Venue: Auditorium

Abstract: New upcoming field of Nanotechnology and its use in healthcare is a leading research topic worldwide. Application of different kinds of nanomaterial in the medicine will be discussed. Details of global funding and coordinated research by US Food and Drug Administration will also be described.


About Speaker: Dr Anil Patri is Director of Nanocore and Chair of the Nanotechnology Task Force at US Food and Drug Administration (FDA). He also serves as the co-chair of US-EU communities of research in Nanotechnology.


[159] Topic: Global surface ozone observations and analyses – Insights from the WMO-GAW Programme and the TOAR

Speaker: Dr. Martin Schultz
Affiliation: Institute for Energy and Climate, Forschungszentrum Jülich, Germany
Date (yyyy-mm-dd): 2015-10-26
Time: 15:30hr
Venue: Auditorium

Abstract: Ozone is an atmospheric trace gas which is important to mankind in several regards: first, it is a harmful air pollutant affecting health and ecosystems, second, it acts as greenhouse gas and is the second or third most important radiative forcing agent, and, third, in the stratosphere it protects the life on Earth from harmful UV radiation. Due to anthropogenic activities and possibly climate change, the concentrations of ozone in the lower atmosphere have changed considerably from pre-industrial times to present. Nowadays, measured ozone concentrations near the surface are almost twice as large as when ozone was first measured reliably in the 1950s or 1960s. In the troposphere, ozone is formed through chemical reactions of multiple precursors, and because of the large variability of emissions of such precursors, ozone concentrations also vary substantially even on regional scales. The World Meteorological Organisation coordinates the Global Atmosphere Watch Programme to establish reliable, long-term measurements of trace gases and other atmospheric constituents around the globe. Together with data from various regional contributing networks, the surface ozone observations collected in GAW allow for a reasonable assessment of tropospheric ozone changes, although many world regions are still severely under-sampled. In the Tropospheric Ozone Assessment activity, a large group of international researchers attempts to analyze and synthesize all available information on tropospheric ozone and evaluate recent ozone changes. In Jülich, these activities are supported through building up the world’s largest collection of surface ozone data. These data are stored in a relational database and made available for research use through a comfortable web interface. The presentation will give an introduction to tropospheric ozone, the current measurement network, its global distribution, and the status of the TOAR database.


About Speaker: Dr. Martin Schultz, Head Global Atmospheric Modeling, Institute of Energy and Climate Research (IKE-8 Troposphere), Research Center Julich, Julich, Germany is involved in various international projects like MACC, LRTAP, GEIA, SPACR, GAW, TOAR, etc. He is also responsible for the data center of Tropospheric Ozone Assessment Report (TOAR).


[140] Topic: Interstellar Dust and its Modeling

Speaker: Ranjan Gupta
Affiliation: IUCAA
Date (yyyy-mm-dd): 2015-08-18
Time: 15:30hr
Venue: Auditorium

Abstract: Its is well known that the interstellar dust plays the most important role in which the light seen form stars suffers extinction. Conventional models assume Mie theory of light scattering with solid spheres and other shapes of silicate and graphite particles of different sizes. An extension of this theory was Effective Medium Theory (EMT) which tries to explain some of the observed interstellar properties. Recent space probes have confirmed that the dust grains are highly porous and fluffy (i.e. aggregates or clusters) rather than having regular shapes (spherical, cylindrical or spheroidal) and homogeneous in compositionand structure. Since their is no exact theory for calculation of scattering properties of such irregular, inhomogeneous particles, recently our group has used Discrete Dipole Approximation (DDA) method and the results of this investigation will be discussed. The model uses a composite fluffy dust grain for explaining most of the average observed interstellar extinction curves and also polarization. Another parameter which needs to be constrained by the dust models is the interstellar abundances of Carbon and Silicon which is usually overestimated by the solid dust models but ourmodel predicts closer match to the observed ISM abundances. Recently, we have used our composite dust model to characterize the dust properties in about 50 different directions in our galaxy. The Silicate dust emission features at 10 and 18 microns is also explained by our composite grain model which helps in understanding the dust characteristics in the circumstellar dust shells around stars.


About Speaker: Ranjan Gupta is a senior professor at IUCAA


[139] Topic: The HIF/Photosphere Interactions in Cepheids and RR Lyraes and multi-phase PL/PC Relations

Speaker: Prof. Shashi M. Kanbur
Affiliation: Department of Physics, State University, New York
Date (yyyy-mm-dd): 2015-08-11
Time: 15:30hr
Venue: Auditorium

Abstract: We provide strong empirical evidence for a nonlinearity in the Cepheid Period-Luminosity (PL) relations at a number of wavelengths using Galactic, LMC and SMC multi-wavelength data from published sources. We provide a possible theoretical explanation for this that involves the interaction of the stellar photosphere and hydrogen ionization front and show that this has implications for Period-Color and Amplitude-Color (PCAC) relations as well. We extend our analysis to look for nonlinearities in PCAC relations for RR Lyraes. We show the importance of considering the way PL/PC relations vary as a function of period and phase and discuss the implications for stellar modeling, the extra-galactic distance scale and estimate of Hubble constant.


About Speaker: Shashi Kanbur is Professor and Chair at Department of Physics at State University of New York


[138] Topic: Identification of YSOs and star formation scenario in the Auriga Region

Speaker: Vinay Tripathi
Affiliation: IIT Delhi
Date (yyyy-mm-dd): 2015-07-24
Time: 15:00hr
Venue: Auditorium

Abstract: This work presents a multiwavelength study of the Auriga region. It includes the investigation of the evolutionary stages, disk properties and other parameters like Temperature, Mass etc. of Young Stellar Objects (YSOs) across the Auriga region by modeling the broadband optical to mid-infrared (MIR) Spectral Energy Distributions (SEDs). The YSOs are classified into different classes based on the parameters determined from their SED response (Robitaille et al.,2007) and are then being compared with the Classes obtained from near infrared (NIR) to mid infrared (MIR) spectral indices α to test the robustness of the SED model. Mass and age of the YSOs calculated from the modeling has been compared with the values obtained from optical Color Magnitude Diagram analysis. The spatial distribution of Class I & FLAT class predicts triggered star formation.


About Speaker: IIT Delhi MSc Student doing summer project at ARIRES


[131] Topic: Probing the Universe with Cosmic Microwave Background Radiation

Speaker: Prof. T. R. Seshadri
Affiliation: Delhi University
Date (yyyy-mm-dd): 2015-06-26
Time: 15:30hr
Venue: Auditorium

Abstract: Cosmic Microwave Background (CMB) is the cleanest signal from the early phase of the universe. One believes this is intrinsically isotropic, un-polarized and has a blackbody spectrum. Hence any deviation from these features provides a very good handle to understand the physical phenomenon both at the surface of last scatter and after that epoch as the photons of CMB travels towards us. The talk will essentially highlight some of the physical processes in the Universe which can produce these deviations.


About Speaker: Prof. T. R. Seshadri is senior professor at the Physics and astrophysics department of Delhi University.


[127] Topic: Polarimetry of R Aquarii - A Nearby Exploding Star

Speaker: Prof. U. C. Joshi
Affiliation: PRL, Ahamedabad
Date (yyyy-mm-dd): 2015-05-01
Time: 15:30hr
Venue: Auditorium

Abstract: R Aquarii is a nearby unique symbiotic star. The most notable observation is that R Aqr varies in brightness over the course of 387 days, going from an 11th magnitude star to a 6th magnitude star. Apart from this, it show peculiar polarization behaviour. Our earlier study on this source showed strong wavelength dependence of polarization and position angle which also showed strong time dependence. The variation in polarization in U-band was found to be much larger compared to that in longer wavelengths. To understand the long term polarization behaviour, we have been caring out polarimetry on this source since 1995 from Mt Abu observatory, India. In the talk, general characteristics of R Aqr will be discussed along with the focus on the polarization behaviour of this peculiar star.


About Speaker: Prof. U. C. Joshi was a senior professor and chairman of Astronomy and Astrophysics Division of PRL, Ahmedabad.


[119] Topic: Astrophysics in the fast time domain: capabilities and selected results from the Thai 2.4m telescope

Speaker: A. Richichi
Affiliation: National Astronomical Research Institute of Thailand, Chiang Mai, Thailand
Date (yyyy-mm-dd): 2015-04-13
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: Abstract:- I will present the rapid scientific and technological expansion taking place at the National Astronomical Research Institute of Thailand, the leading institution for astronomy in South-East Asia. The NARIT science group includes scientists with a broad range of interests spanning from solar system objects, to exoplanets, to stellar physics and cosmology. Alongside with a several 50 to 70-cm class telescopes, some of which are fully robotic, the flagship facility is the new Thai National 2.4-m Telescope (TNT), equipped with spectrographs and imaging cameras. TNT is open for observations mostly in the dry season (approx. October to May). I will discuss the characteristics of the site and the opportunities for telescope access and collaboration. I will then discuss in particular ULTRASPEC, a visitor instrument built by a Consortium of UK institutes, based on a low-noise, frame-transfer EMCCD with high-quality optics and high-time resolution capabilities extending to few milliseconds: a niche for which no other observatory is similarly equipped in the longitude range of TNT. By using a highly flexible scheme of subarray reading, sampling rates as fast as 400Hz can be achieved. I provide examples of new exciting results in areas such as eclipsing binaries, cataclysmic variables, flickering, exoplanet transits, and occultations by the Moon and other solar system bodies.


About Speaker: He is Senior Researcher at NARIT, Thailand


[117] Topic: Structural Studies of Eight Bright Rimmed Clouds in Southern Hemisphere

Speaker: Saurabh Sharma
Affiliation: ARIES
Date (yyyy-mm-dd): 2015-04-07
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: We have presented wide field deep NIR survey of eight regions containing BRCs to study the initial configuration of the YSOs and their nature of interaction with parent molecular clouds. The completeness limit for our observations in K band is ~18 magnitude. For our sample of BRC having distance around 2-3 kpc, we can detect upto sub-solar mass protostars. In addition to mid-infrared images and near-infrared extinction maps, we have identified and classified numerous YSOs, analyzed their spacings, and performed basic spatial distribution measurements and analyses. We identified and classified 100-300 YSOs in different regions with no more than 10-50 expected to be residual contaminators such as broad-line AGNs. Of those, 60 % are classified as IR excess stars, 20% are classified as CTTS, and 15%, 5% are classified as Class II and Class 0 protostars, respectively. We have also presented a purely algorithmic method to isolate local density enhancements in point source distributions from a more diffuse, poorly sampled, and potentially varying density background that uses no smoothing. This method was applied to our survey, extracting eight cluster cores of 10 or more YSO members. Of the identified YSOs, ~60% are members of one of these cores. We have demonstrated that protostars are found in regions of marginally higher surface densities than the more evolved pre-main-sequence stars with disks. The mean of the median spacings of YSOs (regardless of class) in the eight cores isolated here is ~0.06 pc. There suggestion by other investigations (e.g., Teixeira et al. 2006) that Jeans fragmentation is a worthwhile starting point for understanding primordial structure in star-forming regions. In that light, we infer the natal cloud properties from the mean YSO spacing and an assumed temperature of 20K, arriving at properties that are similar to those reported as probable cluster-forming clumps in infrared dark clouds by Rathborne et al. (2006).


About Speaker: Scientist


[110] Topic: On Characterization of trajectories in Restricted 3-Body problem with Radiation Pressure: Application Binary stellar System

Speaker: Dr. M.K.Das
Affiliation: University of Delhi South Campus
Date (yyyy-mm-dd): 2014-11-24
Time: 15:30hr
Venue: Auditorium

Abstract: Mathematical formulation of the stability of orbits in Restricted 3-Body Problems have been described. In this connection the computation of Poincare section method and wavelet analysis has been described with a view to analyze the nature of orbits in Sun-Jupiter system. Further the extension of the work to include the effect of radiation has been discussed. Such a framework has been used to discuss the stability of orbit in Binary stellar system Kruger-60 and RW-Monocerotis.


About Speaker: Prof. at Institute of Informatics & Communication University of Delhi South Campus


[107] Topic: Aerosol chemistry and acid rain

Speaker: Dr P S P Rao
Affiliation: IITM, Pune
Date (yyyy-mm-dd): 2014-11-17
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: Aerosol chemistry is important in studies related to radiative forcing, air quality, climate change etc. Chemical composition of precipitation reflects the chemical status of the atmosphere. These studies are needed to understand the deposition fluxes, biogeochemical cycles of important nutrients i.e., N and S. The effects of acid rain on forests, soils, lakes and monuments will be presented. The collection and analysis of precipitation, ionic composition of precipitation in different environments will be presented. The non-sea salt components, neutralization factors of various ions will be explained. Source identification of various ions will be presented. Long term trends in precipitation chemistry will be shown. The collection and analyses of aerosols and the aerosols chemistry in different environments will be shown.


About Speaker: Speaker is a Senior Scientist at IITM, Pune


[104] Topic: Planet formation in protoplanetary disks: A Spitzer IRS survey of young stars in nearby star forming regions

Speaker: Manoj Puravankara
Affiliation: TIFR
Date (yyyy-mm-dd): 2014-11-07
Time: 15:30hr
Venue: Auditorium

Abstract: Protoplanetary disks are the birth places of planetary systems. Most young stars are surrounded by such planet forming disks. The onset of the processes associated with planet formation significantly alter the radial and vertical structure of the disks, modify the gas and dust content in them, and cause grain growth and crystallisation of the dust in the disks. Observationally, these structural and evolutionary changes are best studied at infrared wavelengths. As part of a large Spitzer Infrared Spectrograph (IRS) survey, we have obtained and analysed mid-infrared (5-40 micron) spectra of several hundred young protoplanetary disks in the nearby star forming regions. I will present the main results of this survey and discuss their implications for our understanding of the early stages of planet formation and the evolution and eventual dissipation of protoplanetary disks.


About Speaker: Manoj is a faculty at TIFR


[106] Topic: Seeing what we hear: finding electromagnetic counterparts for gravitational wave sources

Speaker: Varun Bhalerao
Affiliation: DST-INSPIRE Faculty Fellow, IUCAA
Date (yyyy-mm-dd): 2014-11-07
Time: 11:00hr
Venue: ARIES Audotorium

Abstract: Within this decade, a global network of advanced gravitational wave detectors including LIGO-India are expected to detect various gravitational wave sources. These detectors can yield certain parameters of the gravitational wave source, but complementary studies in electromagnetic wavelengths are crucial for a complete astrophysical understanding. In this talk, I will talk about the proposed electromagnetic counterparts of these sources, and the extremely challenging problem of detecting them. I will highlight why India forms a key node in this global effort, and discuss prospects of optical, IR, radio and X-ray follow-up from India.


About Speaker: Varun Bhalerao is a young scientist working at IUCAA Pune.


[101] Topic: Luminous SN 2012aa : Implication of shock interaction on the observed properties

Speaker: Rupak Roy
Affiliation: Oskar Klein Centre, Sweden
Date (yyyy-mm-dd): 2014-10-30
Time: 15:30hr
Venue: Auditorium

Abstract: Recent development on supernova research has confirmed that there is a distinct class of events which are more luminous than canonical core-collapse supernovae (CCSNe). Typically they show a broad peak (~ -21 mag) with a shallower decline rate than normal events. SN 2012aa, which was discovered in a relatively distant (redshiftz ≈ 0.08) host galaxy on 29.6 January 2012 UT by the Lick Observatory Supernova Search (LOSS), has similar characteristics. The event was also detected by the Catalina Real-Time Transient Survey (CRTS) during its rising phase, with peak apparent unfiltered magnitude ~ 18. From optical spectra it was characterized as a Type Ic SN, although photometrically it is quite distinct from canonical Type Ic events. The photometric and spectroscopic follow-up over a span of 100 days clearly shows the signature of interaction of the SN-shock with the circumsteller medium (CSM). The post-maximum decay rate of this event is roughly 0.012 mag/day. This is much lower than that of normal stripped-envelope CCSNe (~0.06 mag/day) and comparable to the decay rate of  superluminous events like CSS100217 and SN 2007bi. However beyond 60 days, the decay rate becomes comparable with that of radioactive 56^Co. Here, I shall present the optical photometric and spectroscopic follow-up observations of this event, along with detailed analysis of the light curve and spectra, which demonstrate the interaction of SN-shock with the CSM.


About Speaker: Postdoc at Oskar Klein Centre, Sweden http://okc.albanova.se/


[99] Topic: Accretion processes on Black Holes: A review

Speaker: Sandip Chakrabarti
Affiliation: S.N. Bose National Center for Basic Sciences
Date (yyyy-mm-dd): 2014-10-17
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: We discuss how incomplete the models of thin, thick, slim or ADAF disks are. We show that all the corrected solutions of the above models can be recovered from transonic accretion disks which are advective in nature by definition. We present viscous transonic solutions with radiative transfer, and numerical simulations resutls to show their stability. Finally, we show results of data fitting using the generalized transonic flow solutions.


About Speaker: Sandip is well-known physicist and Senior Professor at S.N. Bose National Center for Basic Sciences.


[100] Topic: Persistent Organic Pollutants – A Global issue

Speaker: Dr Ishwar Chand
Affiliation: Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, Chi
Date (yyyy-mm-dd): 2014-10-13
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: Persistent Organic Pollutants are organic chemical substances those persist in the environment and pose a risk of adverse effects to human health and environment. These are global pollutant, due to their longer life, and migrate over long distances. Most POPs generated in one country can and do affect people and wildlife far from where they are used and released. They persist for long periods of time in the environment and can accumulate and pass from one species to the next through the food chain. Considering their global impact, multilateral environmental agreement (United Nations treaty) is signed in Stockholm, Sweden, in May 2001 to reduce or eliminate the production, use, and/or release of 12 key POPs. More details on POPs will discusses during the presentation.


About Speaker: Speaker is TWAS-CAS Postdoctoral Fellow at , Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China


[87] Topic: The progress in detection of p-mode spectra of roAp stars: Alpha Circini and Gamma Equulei

Speaker: Dr. David Mkrtichian
Affiliation: National Astronomical Research Institute of Thailand (NARIT) 191 Siriphanich Bld
Date (yyyy-mm-dd): 2014-07-08
Time: 15:30hr
Venue: Auditorium

Abstract: I will give the review on the spectroscopic methods for search for rapid oscillations in magnetic chemically-peculiar stars and present our recent results. For the roAp star Gamma Equulei we discovered 4 new p-modes. These frequencies, in concert with previously known, exibits well defined 62.8 $muHz general frequency spacing in the oscillation spectrum and in echelle-diagram. We concluded, that consecutive overtones of even and odd modes are excited in Gamma Equulei. We found the increase of pulsation amplitude from the photosphere to upper layers and existence transition layer at superficial layer at the atmosphere above which the amplitude of pulsations is decreasing. I will present a discovery of a rich, sub-meter-per-second amplitude p-mode spectrum of roAp star Alp Cir that is based on the HARPS precise radial velocity time-series. Discovered spectrum consist of 36 oscillation modes in the interval of 2173-2641 $mu$Hz and ranging in amplitude from 46 m/s to 56 cm/s. The density of frequencies and their spacings in the spectrum indicates about first detection of excited high-degree (l>3) modes in a spectrum of a roAp star. These discoveries established a new detection limits in the asteroseismology of roAp stars and shows the need for updates in theory and pulsation models of magnetic stars.


About Speaker: Dr. Mkrtichian is senior researcher at NARIT, Thailand


[85] Topic: The oEA stars

Speaker: Dr. David Mkrtichian
Affiliation: National Astronomical Research Institute of Thailand (NARIT) 191 Siriphanich Bld
Date (yyyy-mm-dd): 2014-07-01
Time: 15:30hr
Venue: Auditorium

Abstract: I will present the review on results of studies of a new class of pulsating mass-accreting stars in the semi-detached Algol-type systems. I will discuss the advantages for studies of oEA stars for asteroseismology, the problem of non-radial mode identification and will show the typical peculiarities of this class of variables based on results of 14 years of photometric and spectroscopic monitoring of selected oEA systems.


About Speaker: Dr. Mkrtichian is senior researcher at NARIT.


[84] Topic: Low energy dispersion relations from Dimension-five Scalar Photon mixing operators and their possible imprint on radiations from compact objects.

Speaker: Dr. Avijit Ganguly
Affiliation: Department Of Physics, MMV
Date (yyyy-mm-dd): 2014-06-26
Time: 15:30hr
Venue: ARIES auditorium

Abstract: Identification and search for possible dark matter candidates has occupied an important place in modern day cosmology. Axion, Chameleon, Dilaton, Kaluza Klien excitations, are some of the possible candidates of ark matter. These particles are generally of two types (i) pseudo-scalar (ii) scalar. Except for the pseudo-scalar particle Axion ( postulated to solve the strong CP problem), others originate in unified theories of gravity with U(1) gauge theory. However, in-spite of their difference in origin; the operator structure of their interaction term with photon, have mass dimension equal to five. Which is makes the theory perturbatively non renormalizable. This aesthetically unpleasant interaction ,introduces two additional phenomena, (a) it makes the vacuum optically active (b) In the presence of a back ground magnetic field, some of the physical modes of the theory show signs of instability---in some energy interval. Some of these and related issues will be discussed in this talk. Possible ways to identify the imprints of such interactions from astrophysical objects will also be discussed.


About Speaker: He is professor in Banaras Hindu University


[75] Topic: Regional modeling of air pollutants in South Asia: present status and future directions

Speaker: Dr. Rajesh Kumar
Affiliation: Advanced Study Program (ASP), National Center for Atmospheric Research (NCAR), B
Date (yyyy-mm-dd): 2014-05-20
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: The concentrations of key trace gases and aerosols are increasing rapidly in the atmosphere of South Asia owing to growing population and associated increase in human activities. These rising concentrations can potentially affect the air quality, atmospheric chemistry, agriculture, ecosystems, freshwater resources and climate, and therefore pose a serious threat to the health, food and water security of billions of people living in South Asia. A recent study shows that premature mortality rates in South Asia due to air pollution are among highest in the world. Therefore, it is very important to understand the processes controlling the distribution and variability of pollutants in this region. However, the available in situ observations of trace gases and aerosols lack sufficient space-time coverage to address this problem and thus use of chemical transport model results and satellite observations becomes essential to advance our understanding of air pollution in this region. In this talk, I will begin with an overview of air pollution problem in South Asia and show how this problem is different from what other parts of the world are facing. Next, I will illustrate the potential of Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to help the interpretation of in situ and satellite observations in South Asia through application of WRF-Chem to three problems of scientific interest. These include simulations of wintertime carbon monoxide (CO) pollution, a typical pre-monsoon season dust storm, and black carbon aerosol distribution. In the end, I will highlight the scope of improvement in present set-up of WRF-Chem and present an outlook towards future research in South Asia.


About Speaker: He is ASP fellow at NCAR, Boulder, USA.


[73] Topic: Bio-energy from Waste Water Treament

Speaker: Dr. Y V Swamy
Affiliation: Indian Institute of Chemical Technology (IICT), Hyderabad
Date (yyyy-mm-dd): 2014-04-16
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: Chemical and allied industries in India are poised for higher growth in the coming decade. Due to stringent environmental regulations, the market for technologies related to treatment of industrial waste and its utilization is expected to grow further. Appropriate technologies, specifically the ones that recover value added products, shall find market without much difficulty. A sustainable hybrid waste/wastewater treatment methodology, capable of removing multiple pollutants along with renewable energy generation is another area that has immense potential. Conventional treatment processes often fail due to varied characteristics of the waste water. Anaerobic dark fermentation treatment produces methane, which is again a greenhouse gas. Hence, a novel approach has been made to produce hydrogen using pre-treated mixed culture. An effort also has been made to produce bio-plastic and bio-electric from the anaerobically treated waste water. By integrating these process steps COD, BOD and TDS could be reduced to acceptable limits besides producing energy by these dual approach. More details will be presented during the talk.


About Speaker: Speaker is a Chief Scientist and Head of Bioengineering and Environmental Centre (BEEC) at Indian Institute of Chemical Technology (IICT), Hyderabad. He is actively involved on Climate Change and Environmental research.


[68] Topic: MHD wave modes and their energy flux in the realistic 3D magnetic flux tube(s) configurations

Speaker: Viktor Fedun
Affiliation: The University of Sheffield,
Date (yyyy-mm-dd): 2014-03-25
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: Photospheric motions, such as granular buffeting or vortices at the foot-point of magnetic flux tubes, could excite MHD waves, which propagate upwards though the solar atmosphere towards corona. In this talk I will show the results of 3D numerical simulation of generation and propagation of slow/fast magnetoacoustic and torsional Alfv'en modes in the localised waveguides and determine the energy flux they carry along the magnetic field lines. Also, the new analytical approach in construction of a system of multiple magnetic flux tubes, for example, pair of open tubes and complex mixed open tube configurations with curvature and asymmetry, will be discussed. This method provides an opportunity to build a range of analytical models of magnetic field configurations that will most realistically capturing magnetic structures of the lower solar atmosphere. The model includes a number of free parameters, which makes the solution applicable to a variety of other physical problems and it may therefore be of more


About Speaker: Dr. Fedun is in The University of Sheffield. His research interest is mathematical modelling of physics of solar/space plasmas, sun-solar wind and solar-terrestrial systems.


[69] Topic: MHD wave modes and their energy flux in the realistic 3D magnetic flux tube(s) configurations

Speaker: Viktor Fedun
Affiliation: The University of Sheffield,
Date (yyyy-mm-dd): 2014-03-25
Time: 15:30hr
Venue: ARIES Auditorium

Abstract: Photospheric motions, such as granular buffeting or vortices at the foot-point of magnetic flux tubes, could excite MHD waves, which propagate upwards though the solar atmosphere towards corona. In this talk I will show the results of 3D numerical simulation of generation and propagation of slow/fast magnetoacoustic and torsional Alfv'en modes in the localised waveguides and determine the energy flux they carry along the magnetic field lines. Also, the new analytical approach in construction of a system of multiple magnetic flux tubes, for example, pair of open tubes and complex mixed open tube configurations with curvature and asymmetry, will be discussed. This method provides an opportunity to build a range of analytical models of magnetic field configurations that will most realistically capturing magnetic structures of the lower solar atmosphere. The model includes a number of free parameters, which makes the solution applicable to a variety of other physical problems and it may therefore be of more.


About Speaker: Dr. Fedun is working in The University of Sheffield. His research interest is the mathematical modelling of physics of solar/space plasmas, sun-solar wind, solar-terrestrial systems.


[58] Topic: STELLAR PULSATION: A NON LINEAR PERSPECTIVE

Speaker: Prof. M. K. Das
Affiliation: University of Delhi
Date (yyyy-mm-dd): 2013-11-25
Time: 15:30hr
Venue: Auditorium

Abstract: We have studied the temporal characteristics of different nonlinear stellar pulsation models in the nonlinear framework. In general the temporal behavior i.e., time series of amplitude variation are non-stationary and therefore the linear framework becomes inadequate for further characterization. Therefore, we have used wavelet analysis to investigate their characteristics in the time-frequency domain. Further the time series obtained in most of these model suggests period doubling and chaotic behavior for certain control parameters, in the phase space. As usually only one observational parameter is measured in a given setting, it is used to reconstruct an attractor in the phase space using phase space reconstruction method. Further characterization of the attractor and hence the time series ,obtained for various models, have been made using the recurrence quantification analysis (RQA).


About Speaker: Prof. Das is at Institute of Informatics & Communication University of Delhi South Campus.


[54] Topic: BLACK HOLES OF GENERAL RELATIVITY

Speaker: Dr. G. Srinivasan
Affiliation: Former Jawaharlal Nehru Fellow, Raman Research Institute (Retired)
Date (yyyy-mm-dd): 2013-10-04
Time: 11:00hr
Venue: Auditorium

Abstract: The details about BLACK HOLES OF GENERAL RELATIVITY will be discuss and the colloquium will be non technical.


About Speaker: Dr. G. Srinivasan is Former Jawaharlal Nehru Fellow and retired from Raman Research Institute, Bangalore.


[50] Topic: HI gas in absorption towards the central regions of radio galaxies

Speaker: Dr. Yogesh Chandola
Affiliation: NCRA, Pune
Date (yyyy-mm-dd): 2013-10-03
Time: 15:30hr
Venue: New Auditorium

Abstract: In radio galaxies, an understanding of the gaseous components in their environments as well as in the nuclear regions could provide insights towards understanding the triggering of radio activity, understanding fueling processes, probing jet-cloud interactions and also constraining orientation dependent unification schemes. Detection of HI via 21-cm absorption lines towards compact radio sources (GPS, CSS and compact cores of the larger radio sources) has been an important tool to study this cold neutral component of the circumnuclear gas in the host galaxies of AGN. This gas could be either part of the interstellar medium (ISM) of the host galaxy, or be a constituent of the circumnuclear tori or disk in the central region of the host. I present the results of HI 21-cm absorption line studies towards the central regions of radio galaxies. These observations were made with the Giant Metrewave Radio Telescope(GMRT) to detect HI gas via absorption, study the kinematics and distribution of this cold atomic gas in their central regions. We detected new HI absorption towards seven radio sources in our studies done for a sample of low luminosity nearby compact CSS & GPS radio sources. Within the uncertainties, the detection rates and column densities are similar to the more luminous objects, with the GPS objects exhibiting a higher detection rate than for the CSS objects. In HI absorption studies towards the cores of larger radio sources, considering observations of similar sensitivity, we find that the detection rate of HI absorption towards the cores of larger (>15 kpc) sources is only ∼15 per cent, compared with ∼57 per cent for CSS and GPS objects, suggesting an evolution in the gaseous content of the host galaxies as the radio sources age and grow in size. I will also summarize the results of our HI absorption observations towards the central regions of rejuvenated radio sources.


About Speaker: Post Doctoral Fellow in NCRA, Pune.


[45] Topic: Molecular forms of PAH in diverse Astrophysical objects

Speaker: Shantanu Rastogi
Affiliation: University of Gorakhpur
Date (yyyy-mm-dd): 2013-09-04
Time: 15:30hr
Venue: Auditorium

Abstract: The mid infrared bands and their relation to aromatic molecules i.e. the PAH hypothesis will be discussed. The feature variations are related to object type and have been correlated with different PAH populations. Study of different varieties of PAHs and emission models to match the IR bands will be presented. Possible evolution of PAH varieties and their relation to object type will be discussed.


About Speaker: Professor at Department of Physics, University of Gorakhpur, Gorakhpur. Dr. Rastogi works on astrophysics.


[37] Topic: Methane concentrations over Monsoon Asia as observed by satellite sensors: Signals of methane emission from rice cultivation

Speaker: Prof. Sachiko Hayashida
Affiliation: Nara Womens University, Nara, Japan
Date (yyyy-mm-dd): 2013-08-08
Time: 15:15hr
Venue: ARIES Auditorium

Abstract: We have analyzed the column-averaged CH4 concentration (xCH4) using scanning imaging absorption spectrometer for atmospheric chartography (SCIAMACHY) and compared the data with the bottom-up emission inventory datasets and other satellite-derived indices such as the land-surface water coverage (LSWC) and the normalized difference vegetation index (NDVI). The geographical distribution of high CH4 values corresponds to strong emissions from regions where rice is cultivated, as indicated in the inventory maps. The Pearson’s correlation coefficients (r) between xCH4 and the rice emission inventory data are observed to be greater than ~0.6 over typical rice fields, with outstanding r-values of ~0.8 in the Ganges Basin and the Sichuan Basin. This suggests that the emission of CH4 from rice cultivation mainly controls the seasonality of the CH4 concentration over such regions. The correlation between xCH4 and LSWC and NDVI are also as large as 0.6. In Southeast Asia, the r-values of xCH4 with bottom-up inventory data that includes all categories are not as high as those with the emission, as estimated from the rice category only. This is indicative of the relative importance of rice emissions among all other emission categories in Southeast Asia. In addition, I would like to introduce our research activities under the project "Characterization and Quantification of global methane emissions by utilizing GOSAT and other satellite sensors" sponsored by Ministry of Environment Japan.


About Speaker: Professor Hayashida contributed to the Improved Limb Atmospheric Spectrometer (ILAS) Science Team as a leader of validation for aerosol extinction measurements. She has also worked on Stratospheric Aerosol and Gas Experiment (SAGE) II and other satellite sensors. She investigated the composition of Polar Stratospheric Clouds (PSCs) and their effects on chemical processes related to polar ozone destruction, by utilizing ILAS data. Her group also developed a new simple scheme to construct synoptic maps of chemical species by combining trajectory mapping with a photochemical box model (Chemical Species Mapping on Trajectories). She received Horiuchi Award from Japan Meteorological Society in 2002 for her scientific achievements. Later she extended her study to tropospheric ozone, focusing on the spatiotemporal variation of tropospheric ozone distribution. She was a member of SPARC SSG from 2005 through 2008, and contributed to the joint scientific meeting of SPARC/IGAC in Kyoto, 2009 as one of the organizing committee members. Now, her most recent interest is methane emission from agriculture.


[29] Topic: STELLAR PULSATION: A NONLINEAR PERSPECTIVE

Speaker: Prof. M. K. Das
Affiliation: University of Delhi
Date (yyyy-mm-dd): 2013-07-05
Time: 15:30hr
Venue: Auditorium

Abstract: We have studied the temporal characteristics of different nonlinear stellar pulsation models in the nonlinear framework. In general the temporal behavior i.e., time series of amplitude variation are non-stationary and therefore the linear framework becomes inadequate for further characterization. Therefore, we have used wavelet analysis to investigate their characteristics in the time-frequency domain. Further the time series obtained in most of these model suggests period doubling and chaotic behavior for certain control parameters, in the phase space. As usually only one observational parameter is measured in a given setting, it is used to reconstruct an attractor in the phase space using phase space reconstruction method. Further characterization of the attractor and hence the time series ,obtained for various models, have been made using the recurrence quantification analysis (RQA).


About Speaker: Prof. Das is presently associated with Institute of Informatics & Communication University of Delhi South Campus.


[31] Topic: Asteroseismology in South Africa and the impact of Kepler data on oscillating Eclipsing Algols (oEAs)

Speaker: Prof. Chris Engelbrecht
Affiliation: University of Johannesburg, South Africa
Date (yyyy-mm-dd): 2013-07-03
Time: 15:30hr
Venue: Auditorium

Abstract: The study of pulsating stars has a long and proud tradition in South Africa. The current research environment in this field in South Africa will be reviewed. In recent years, South African researchers have joined the asteroseismology consortium studying data from the Kepler space telescope. One prominent project, the study of oscillating eclipsing Algols using Kepler data, will also be reviewed.


About Speaker: Prof. Engelbrecht is working at the Department of Physics, University of Johannesburg, South Africa.


[30] Topic: A study of correlations between metallicity and opacity-driven pulsation in hot stars in the LMC

Speaker: Prof. Chris Engelbrecht
Affiliation: University of Johannesburg, South Africa
Date (yyyy-mm-dd): 2013-07-01
Time: 15:30hr
Venue: Auditorium

Abstract: Serious questions concerning our knowledge of stellar structure and evolution can be addressed through the asteroseismology of hot stars in the LMC and SMC. There is an apparent discrepancy between the theoretical prediction of pulsational instability in B stars and what w observe in nature. This discrepancy appears to relate to the way the metal content of hot stars affects their internal structure. The LMC and SMC are ideal testing grounds for our theories. A long-term project to study this problem at Sutherland in South Africa will be reviewed.


About Speaker: Prof. Engelbrecht is working at Department of Physics, University of Johannesburg, South Africa.


[15] Topic: PHOTOMETRIC STUDIES OF OPEN STAR CLUSTER Rup32

Speaker: Mr. Sidhant Guliani
Affiliation: Guru Gobind Singh Indraprastha Univeristy, New Delhi
Date (yyyy-mm-dd): 2013-04-29
Time: 14:45hr
Venue: ARIES New Lecture room

Abstract: .


About Speaker: Project Student


[10] Topic: HR diagram and Sahas Theory of Thermal ionization

Speaker: Prof. D. C. Srivastava
Affiliation: DDUGU
Date (yyyy-mm-dd): 2013-04-16
Time: 15:30hr
Venue: New Lecture Hall

Abstract: Application of Sahas Theory of Thermal Ionisation to Specral Types and HR diagram will be discussed. A discussion of Spectral Classification and Sahas Theory will also be presented in the Historical perspectives.


About Speaker: Senior Professor of the Physics Department of Gorakhpur University. Served as its HOD till recently.


[9] Topic: Activity in A-type stars

Speaker: Prof. Luis Balona
Affiliation: South African Astronomical Observatory (SAAO), South Africa
Date (yyyy-mm-dd): 2013-03-26
Time: 15:30hr
Venue: Auditorium

Abstract: Kepler photometry shows that most non-pulsating A-type stars vary with periodstypical of the expected rotation periods. The periodogram is simple and usually consists of a peak and its harmonic with amplitudes typically smaller than 50 ppm. We presume that the variation is rotational modulation caused by spots or some other co-rotating obscuration. This is supported by the distribution of equatorial velocities derived from the photometric periods. From the broadening of the peaks in the periodogram, we estimate that differential rotation in A-type stars is very similar to that in the Sun. Flares on A-type stars have been recently discovered in Kepler data. We show that such flares cannot be attributed to a late-type companion but must originate on the A star itself or an interaction between the A star and a close companion. We also discuss activity in B-type stars and argue that Be stars, in particular, are magnetically active. We present a simple model which explains all major characteristics of Be stars.


About Speaker: http://www.saao.ac.za/~lab/


[5] Topic: The SALT Instrumentation Suite

Speaker: David Buckley
Affiliation: South African Astonomical Observatory
Date (yyyy-mm-dd): 2013-03-12
Time: 15:30hr
Venue: Auditorium

Abstract: Construction of the 10-m Southern African Large Telescope (SALT) was completed in 2005 at a relatively modest cost of $20M and in just 6 years. Following a rather protracted commissioning and science verification phase, during which two major problems were discovered and corrected, briefly reviewed here, it entered full science operations in 2011. This talk will discuss the design and construction of SALT and its First Generation instruments, SALTICAM and the Robert Stobie Spectrograph, and highlight their capabilities, particularly some of the niche observing modes, and will present some examples of initial science results. New SALT instrumentation currently under construction, including the High Resolution Spectrograph and the near IR extension to the RSS, will also be discussed.


About Speaker: SALT Science Director Webpage: http://www.salt.ac.za/about/people-partners/operations-team/david-buckley/


[7] Topic: Thirty Meter Telescope Project Overview

Speaker: Dr. Eric Williams
Affiliation: TMT, CALTECH
Date (yyyy-mm-dd): 2013-03-01
Time: 15:30hr
Venue: Auditorium

Abstract: Thirty Meter Telescope Project Overview


About Speaker: Eric Williams is TMT Optics Group Leader responsible for the design, fabrication, testing and integration of the telescope optics. Eric has been involved in the TMT project for 8 years. Prior to joining TMT, Eric worked in the U.S. Aerospace Industry on a wide range of projects.