| Name: Sipra Hota |
| Affiliation: Indian Institute of Astrophysics |
| Conference ID: ASI2026_218 |
| Title: Unveiling the nature of massive stars in the Young Open Cluster NGC~654 with UVIT |
| Abstract Type: Poster |
| Abstract Category: Stars, Interstellar Medium, and Astrochemistry in Milky Way |
| Author(s) and Co-Author(s) with Affiliation: Sipra Hota(Indian Institute of Astrophysics, Bangalore - 560034, India), Sharmila Rani(INAF–Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy), Annapurni Subramaniam(Indian Institute of Astrophysics, Bangalore - 560034, India) |
| Abstract: The evolution of massive stars is not yet well understood because of their short lifetimes and scarcity. Young open clusters (OCs) provide the best platform to study such stars as they are home to massive stellar populations. NGC 654 is a young Galactic OC with
estimated ages ranging from 16 to 63 Myr and significant differential reddening of E(B−V ) = 0.74–1.16 mag. It hosts massive stars with a confirmed Be star and an emission-line star. The objective of this work is to study the cluster properties, including age, reddening, and the properties of its individual stars, such as effective temperature, luminosity, radius, evolutionary phase, and multiplicity. Here we present the first-ever far-ultraviolet (FUV) photometric study of NGC 654, using UV data from the UltraViolet Imaging Telescope (UVIT) aboard AstroSat. This is the only other cluster observed along with NGC 663 by UVIT to study the Galactic massive stars in the UV. We identify 68 confirmed members with membership probability more than 50% detected in both FUV filters (F148W and F172M). FUV optical color–magnitude diagrams reveal that the UVIT-detected members are predominantly main-sequence (MS) stars, with the Be and emission-line stars located on the redder side of the MS. Among the 68 members, four previously reported eclipsing binaries are identified. Using the spectral energy distribution (SED) modeling technique, we examine the physical properties and multiplicity of these stars, finding that the majority are consistent with single systems, while a small fraction are identified as candidate binaries. Overall, this study highlights the crucial role of UV observations to characterise the binary fraction among massive stars and provides insights into the evolution of the massive binary systems. |
