Presentation for SAC-2012 on Observational Studies of Nearby Galaxies Observational Studies of Nearby Galaxies Researchers are: Students: Sumit Jaiswal, Chrisphin Karthick (Thesis submitted on 2012) Faculties: Amitesh Omar, B. B. Sanwal (till 2010) Research is carried out on topics: 1.Star formation in galaxies 2.Triggering mechanism for star formation Emphasis is on Wolf-rayet galaxies. Multiwav elength Data are taken using: Radio (HI 21cm-line)data:GMRT Optical Photometric data: IGO telescope, ARIES telescopes (1.04m-ST & 1.3m- DFOT), HCT Optical Spectroscopic data:IGO telescope, HCT
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Work done by Sumit & AmiteshThe main aim of this study is to trace features in optical and radio images indicating the trigger
mechanism of massive star formation in these galaxies.
A survey of about 20 WR galaxies in the HI 21cm-line using GMRT and in Hα-line using 1.3-mDevasthal Optical telescope & 2-m IGO telescope is being carried out.
The galaxy sample includes the compact galaxies not showing highly disturbed morphology or
tidal tails and large galaxies not showing nuclear star formation in their SDSS images.
As HI envelop is much bigger than the optical envelop, HI-line is the best tracer for tidal
interactions in galaxies.
If tidal features in HI are not detected, it will indicate a strong consideration of other possible
mechanisms of star formation trigger in galaxies.
As Hα emission is a very good tracer of HII regions, the Hα images therefore show how starformation regions are distributed within their host galaxies with respect to the environmental
effects.
The first results on this observational program are very encouraging. We have traced the
features of tidal interaction in few galaxies (e.g., Mrk 996, Mrk 005) which were previously cited