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arXiv · 2509.10608

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

C. S. Kochanek·K. Z. Stanek·T. A. Thompson·T. Jayasinghe
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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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C. S. Kochanek, K. Z. Stanek, T. A. Thompson, T. Jayasinghe. 2025-09-12. The HST Ultraviolet Spectrum of V723 Mon: Additional Evidence of a Stellar Companion. https://arxiv.org/abs/2509.10608

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