Abstract Details

Name: Chayan Mondal
Affiliation: Indian Institute of Astrophysics
Conference ID: ASI2020_548
Title : Tracing young star forming clumps in the nearby flocculent spiral galaxy NGC 7793 with UVIT
Authors and Co-Authors : Chayan Mondal, Annapurni Subramaniam, Koshy George
Abstract Type : Poster
Abstract Category : Extragalactic Astronomy
Abstract : Star formation in galaxies is a hierarchical process with a wide range of scale from smaller clusters to larger stellar complexes. Here, we present an ultra-violet imaging study of the nearby flocculent spiral galaxy NGC 7793. The galaxy is observed with two broadband photometric filters F148W (FUV) and N242W (NUV) of the Ultra-Violet Imaging Telescope (UVIT). We find that the disk scale-length estimated in FUV (2.64$\pm$0.16 kpc) is more than that in NUV (2.21$\pm$0.21 kpc) and optical (1.08 kpc). The FUV and NUV luminosity density profiles of the galaxy convey that between radius 3 - 5 kpc in the outer disk, the FUV emission is more dominant than the NUV. These together support the inside-out growth scenario of the disk. With the spatial resolution of UVIT (1 pixel $\sim$ 6.8 pc), we identified 2046 young star-forming regions in the galaxy with radius between $\sim$ 12 - 70 pc, which matches well with the sizes of GMCs detected in the galaxy. Around 61\% of the regions, identified in our study, have age younger than 20 Myr, which points to a recent enhancement of star formation across the galaxy. We also noticed that the youngest star-forming regions, with age $<$ 10 Myr, distinctly trace the flocculent arms of the galaxy. This can be due to the impact of density wave which could have triggered recent star formation along the arms. The estimated masses of the clumps cover a range between $10^3 - 10 ^6 M_{\odot}$. We noticed a hierarchical mass distribution for identified clumps along the spiral arms. We have also studied the nuclear star cluster of the galaxy and found that the stellar populations in the cluster outskirts are younger compared to the inner part.