30th Annual Report 2017-18

AstroSat/UVITReveals Flocculent Spiral inNGC4571 The late-type spiral galaxy NGC 4571 in the constellation of Coma Berenices AstroSat/UVIT in two filters - FUV BaF2 and NUV B4 for 10000 seconds by Kanak Saha and Shyam Tandon . They have derived true colour images of NGC 4571 that show several knots in blue colour of star forming regions (see Figure 5). These star-forming knots, primarily young stars (as inferred from FUV data), are also visible in the SDSS r band + UVIT colour composite image as shown below. The star-forming clumps are not only confined in the central region but all over the galaxy extending to outskirts. We are currently investigating what is igniting such a wide-scale star formation in the galaxy which is apparently lonely, gas-poor, lying in the outskirts of Virgo Cluster. Although not classified, the UVITmorphology indicates that it is a flocculent spiral. the was observed by Figure 5: True colour image of NGC 4571 observed by the Ultra- Violet Imaging Telescope on-board AstroSat. Top image is a colour composite of three bands - HST f555w (red), NUV (green) and FUV (blue). A box of size 54x49 arcsec is highlighted to show the central region of the galaxy - star forming knots (turkish blue clumps) in a ring-like structure. 35