2025/09/16 by Shiraishi, Yuta, Hotokezaka, Kenta, Masuda, Kento +10
#FOS: Physical sciences #Solar and Stellar Astrophysics (astro-ph.SR)
paper · doi:10.48550/arxiv.2509.12808
We report the discovery of two binary systems, each consisting of a slightly bloated G-type main-sequence star and an unseen companion, identified through photometric data from TESS and radial velocity variation from Gaia. High-resolution spectroscopy confirms orbital periods of 1.37 and 2.67 days with circular orbits. The visible components have masses of ∼ 0.9 M_\odot, while the minimum masses of the unseen companions are 1.073+0.058-0.060 M_\odot and 0.919+0.049-0.051 M_\odot, respectively. Assuming tidal synchronization, we estimate the companion masses to be 1.12+0.10-0.08 M_\odot and 1.02+0.15-0.10 M_\odot. The absence of detectable spectral features from the companions rules out main-sequence stars of these masses, suggesting that the unseen companions are likely O/Ne or C/O massive white dwarfs. The short orbital periods imply that these systems are post-common envelope binaries. Their subsequent evolution is uncertain, with possible outcomes including cataclysmic variables, Type Ia supernovae, or accretion-induced collapse, depending on the nature of future mass transfer.