• RENUKA PECHETTI

      Articles written in Journal of Astrophysics and Astronomy

    • The sharpest ultraviolet view of the star formation in an extreme environment of the nearest Jellyfish Galaxy IC 3418

      ANANDA HOTA ASHISH DEVARAJ ANANTA C PRADHAN C. S. STALIN KOSHY GEORGE ABHISEK MOHAPATRA SOO-CHANG REY YOUICHI OHYAMA SRAVANI VADDI RENUKA PECHETTI RAMYA SETHURAM JESSY JOSE JAYASHREE ROY CHIRANJIB KONAR

      More Details Abstract Fulltext PDF

      We present the far ultraviolet (FUV) imaging of the nearest Jellyfish or Fireball galaxy IC3418/VCC 1217, in the Virgo cluster of galaxies, using Ultraviolet Imaging Telescope (UVIT) onboard the AstroSat satellite. The young star formation observed here in the 17 kpc long turbulent wake of IC3418,due to ram pressure stripping of cold gas surrounded by hot intra-cluster medium, is a unique laboratory that is unavailable in the Milky Way. We have tried to resolve star forming clumps, seen compact to GALEX UV images, using better resolution available with the UVIT and incorporated UV-optical imagesfrom Hubble Space Telescope archive. For the first time, we resolve the compact star forming clumps (fireballs) into sub-clumps and subsequently into a possibly dozen isolated stars. We speculate that many of them could be blue supergiant stars which are cousins of SDSS J122952.66$+$112227.8, the farthest star($\sim$17 Mpc) we had found earlier surrounding one of these compact clumps. We found evidence of star formation rate ($4–7.4 \times 10^{–4} \ M_{\odot}$ yr$^{–1}$) in these fireballs, estimated from UVIT flux densities, to beincreasing with the distance from the parent galaxy. We propose a new dynamical model in which the stripped gas may be developing vortex street where the vortices grow to compact star forming clumps due to self-gravity. Gravity winning over turbulent force with time or length along the trail can explain thepuzzling trend of higher star formation rate and bluer/younger stars observed in fireballs farther away from the parent galaxy.

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