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Research

Title
Globular Clusters UVIT Legacy Survey (GlobULeS) I. FUV-optical Color-Magnitude Diagrams for Eight Globular Clusters
Date
2022.09.15
Writer
천문우주학과
게시글 내용

Globular Clusters UVIT Legacy Survey (GlobULeS) I. FUV-optical Color-Magnitude Diagrams for Eight Globular Clusters


Snehalata Sahu, Annapurni Subramaniam, Gaurav Singh, Ramakant Yadav, Aldo R. Valcarce, Samyaday Choudhury, Sharmila Rani, Deepthi S. Prabhu, Chul Chung, Patrick Côté, Nathan Leigh, Aaron M. Geller, Sourav Chatterjee, N. Kameswara Rao, Avrajit Bandyopadhyay, Michael Shara, Emanuele Dalessandro, Gajendra Pandey, Joesph E. Postma, John Hutchings, Mirko Simunovic, Peter B. Stetson, Sivarani Thirupathi, Thomas Puzia, Young-Jong Sohn


We present the first results of eight Globular Clusters (GCs) from the AstroSat/UVIT Legacy Survey program GlobULeS based on the observations carried out in two FUV filters (F148W and F169M). The FUV-optical and FUV-FUV color-magnitude diagrams (CMDs) of GCs with the proper motion membership were constructed by combining the UVIT data with HST UV Globular Cluster Survey (HUGS) data for inner regions and Gaia Early Data Release (EDR3) for regions outside the HST's field. We detect sources as faint as F148W  23.5~mag which are classified based on their locations in CMDs by overlaying stellar evolutionary models. The CMDs of 8 GCs are combined with the previous UVIT studies of 3 GCs to create stacked FUV-optical CMDs to highlight the features/peculiarities found in the different evolutionary sequences. The FUV (F148W) detected stellar populations of 11 GCs comprises 2,816 Horizontal Branch (HB) stars (190 Extreme HB candidates), 46 post-HB (pHB), 221 Blue Straggler Stars (BSS), and 107 White Dwarf (WD) candidates. We note that the blue HB color extension obtained from F148WG color and the number of FUV detected EHB candidates are strongly correlated with the maximum internal Helium (He) variation within each GC, suggesting that the FUV-optical plane is the most sensitive to He abundance variations in the HB. We discuss the potential science cases that will be addressed using these catalogues including HB morphologies, BSSs, pHB, and, WD stars.


https://arxiv.org/abs/2204.12886

저자명
Chul Chung, Young-Jong Sohn