Exploration of UV-bright sources in Globular cluster NGC 3201 using UVIT observations
Manasi Kulkarni, Sonika Piridi, Ranjan Kumar, Ananta C. Pradhan
astro-ph.GA, astro-ph.IM, astro-ph.SR
Submitted: 2026-08-09
Updated: 2026-08-11
Comments: Appected for publication in Journal of Astrophysics and Astronomy (JAA)
License: http://creativecommons.org/licenses/by/4.0/
The gist: We present a comprehensive study of the ultraviolet (UV)-bright stellar population in the globular cluster NGC 3201 using the Ultraviolet Imaging Telescope (UVIT) onboard AstroSat.
Terminology
Abstract
We present a comprehensive study of the ultraviolet (UV)-bright stellar population in the globular cluster NGC 3201 using the Ultraviolet Imaging Telescope (UVIT) onboard AstroSat. By combining far-UV photometry of the UVIT F148W and F169M filters with Gaia and ground-based telescope optical data, we construct UV - optical color-magnitude diagrams (CMDs) to identify UV-bright stellar evolutionary phases. Physical parameters of all detected sources are derived by fitting stellar atmosphere models to the observed multi-wavelength spectral energy distributions (SEDs). The effective temperatures of blue horizontal branch stars (BHBs) span the range 7250 - 11250 K. We identify two extreme horizontal-branch stars (EHBs) with effective temperatures of approximately 25,000 K and 17,000 K; one lies within the cluster core radius (r c =1.3 '), while the other is located outside. We also detect two candidate ``gap'' objects in the transitional phase between HB stars and white dwarfs, which may represent hot blue hook (BHk) stars. For the blue straggler stars (BSSs), we determine effective temperatures, radii, and luminosities through SED fittings, and estimate their masses and isochrone-equivalent ages using PARSEC isochrones. Finally, we studied the normalized cumulative radial distribution of the observed BHB stars, BSSs, MS stars, RGB stars, and variable stars along with the specific frequency of BSSs across the cluster. These results provide new insights into the late-stage stellar evolution and dynamical processes in NGC 3201.
Sources
- Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy
- A New Catalog of Globular Clusters in the Milky Way
Related papers
- Apparent Stability in Self-Gravitating Turbulence and the Evolution of Molecular Clouds
- Two sets of potential-density basis pairs for the study of radial perturbations in collisionless spherical stellar systems
- Constraining reionization-era Ly alpha escape with JELS-MUSE: a highly complete H alpha-selected sample at z about6.1
- Deriving volume density profiles of filaments from observed surface densities
- Little Red Dots and Supermassive Black Hole Seed Formation in Ultralight Dark Matter Halos
- MEGATRON: how the first stars can create an iron metallicity plateau in the smallest dwarf galaxies