The HST Ultraviolet Spectrum of V723 Mon: Additional Evidence of a Stellar Companion

2025/09/12 by C. S. Kochanek, Kochanek, C. S., K. Z. Stanek +5
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #Astronomy and Astrophysical Research #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Solar and Stellar Astrophysics (astro-ph.SR) #Stellar, planetary, and galactic studies

paper · pdf · doi:10.48550/arxiv.2509.10608

openalex publication_date 2025/09/12 · openalex created_date 2025/10/12 · openalex updated_date 2026/07/28

Abstract

V723 Mon is a high mass function (f=1.7Msun) single lined spectroscopic binary with a red giant primary that Jayasinghe et al. (2021) suggested had a black hole as its massive companion. Unfortunately, el-Badry et al. (2022) demonstrated that it had a hotter stellar companion whose detectability in optical spectra was difficult due to its rapid rotation. Here we confirm the presence of the stellar companion with a Hubble Space Telescope STIS ultraviolet spectrum.

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