|  Topic: Review On Interstellar Grain Alignment |
Speaker: RONIK KUMAR
Affiliation: IIT, Roorkee
Date (yyyy-mm-dd): 2014-07-04
Venue: ARIES Auditorium
Abstract: The work toward theoretical understanding of interstellar grain alignment began just after the discovery of polarization of starlight by Hiltner (Hiltner 1949) and Hall (Hall 1949) nearly half a century ago. Interstellar polarization is known to be caused by elongated dust grains aligned with respect to the Galactic magnetic field. Hence One of the easiest ways to determine the magnetic field direction is via polarization of radiation resulting from extinction on or/and emission by aligned dust grains. How reliable the interpretation of the polarization maps in terms of magnetic fields is the issue that the grain alignment theory addresses. Identifying the dominant grain alignment mechanism has proved to be an intriguing problem in grain dynamics (Lazarian et. al. 1997). The review on progress in the field of grain alignment since the work of David-Greenstein(Davis and Greenstein 1951), basic physical processes involved in grain alignment, and the niches in different alignment mechanisms in general interstellar medium and in dense molecular cloud regions are presented. The chemical composition of dust grains are also discussed in the later part because that determine the many properties of dust by studying the spectral features in the Interstellar extinction curve. Various grain models have been proposed to explain the interstellar extinction curve. Grain models are one of the important factors which determine the validity of different alignment mechanisms.
About Speaker: SUMMER FELLOW, INDIAN ACADEMY OF SCIENCE
|  Topic: Multi- Wavelength study of NGC 1931|
Speaker: Abhijeet Anand
Affiliation: IISC Bangalore
Date (yyyy-mm-dd): 2013-07-23
About Speaker: .
|  Topic: Study of a Super-flare, On the RS CVn Binary II PEG|
Speaker: Ansul Kapoor
Affiliation: Project Student
Date (yyyy-mm-dd): 2013-07-15
Venue: New Lecture Room
Abstract: II Peg (HD 224085) is a well known 7.37 mag bright active binary system that displays evidence for star-spots covering a large fraction of the primary photosphere, and has signatures associated with vigorous magnetic activity across the entire electromagnetic spectrum. At a distance of 42 pc, this single lined spectroscopic binary is composed of a 0.8Mo (K2 IV) primary tidally locked in a 6.7 day orbit with a 0.4Mo secondary. On Dec. 16, 2005 a super-flare was observed in the primary sub-giant of this system. The strength of the flare was around 105 times an ordinary flare. The talk will focus on the various aspects of flares in general and primarily of this flare of 2005.
About Speaker: NASI Summer fellow
|  Topic: Near-infrared polarimetric studies of star-forming regions.
Speaker: C. Eswaraiah
Date (yyyy-mm-dd): 2013-06-24
Abstract: I will present few important results based on NIR-polarimetric observations of few star-forming regions by the Japanese group. The discussion will mainly be focused on the dust properties and importance of magnetic fields in cloud and star-formation processes.
About Speaker: Speaker is PDF at ARIES working on star formation.