Everything that glitters is not gold: V1315 Cas is not a dormant black hole

Abstract

The quest for quiet or dormant black holes has been ongoing since several decades. Ellipsoidal variables possibly indicate the existence of a very high-mass invisible companion and are thought to be one of the best ways to find such dormant black holes. This, however, is not a panacea as we show here with one example. We indeed report the discovery of a new semi-detached interacting binary, V1315 Cas, discovered as an ellipsoidal variable. Using data from photometric surveys (ASAS-SN, TESS) and high-resolution spectroscopy, we derived a nearly circular orbit with an orbital period of $P_{\mathrm{orb}}$=34.54 d. The binary system consists of an evolved F-type star primary that is likely still filling its Roche lobe and a B-type star secondary. Using \textsc{phoebe}2, we derived the following masses and radii: for the primary, $M_p=0.84\pm 0.03M_{\odot }$ and $R_p=18.51_{-0.07}^{+0.12}{R}_{\odot }$; for the secondary, $M_s=7.3\pm 0.3M_{\odot }$ and $R_s=4.02_{-2.0}^{+2.3}{R}_{\odot }$. Modeling the evolution of the system with MESA, we found an age of $\sim$7.7e7 years. The system is at the end of a period of rapid non-conservative mass transfer that reversed its mass ratio, while significantly widening its orbit. The primary shows carbon depletion and nitrogen overabundance, indicative of CNO processed material being exposed due to mass transfer. An infrared excess as well as stationary H$\alpha$ emission suggest the presence of a circumstellar or circumbinary disc. V1315 Cas will likely become a detached stripped star binary.

Accepted in MNRAS

References in corpus (22)

• Modules for Experiments in Stellar Astrophysics (MESA)
• The Transiting Exoplanet Survey Satellite
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• Binary Population and Spectral Synthesis Version 2.1: construction, observational verification and new results
• Determining stellar atmospheric parameters and chemical abundances of FGK stars with iSpec
• Physics Of Eclipsing Binaries. II. Towards the Increased Model Fidelity
• Modern stellar spectroscopy caveats
• A red giant orbiting a black hole
• Is HR 6819 a triple system containing a black hole? -- An alternative explanation
• An X-ray quiet black hole born with a negligible kick in a massive binary within the Large Magellanic Cloud
• Identifying quiescent compact objects in massive Galactic single-lined spectroscopic binaries
• A stripped helium star in the potential black hole binary LB-1
• Science with the Ultraviolet Explorer (UVEX)
• Periodic variable A-F spectral type stars in the northern TESS continuous viewing zone
• What are the spectroscopic binaries with high mass functions near the Gaia DR3 main sequence?
• Properties and nature of Be stars 30. Reliable physical properties of a semi-detached B9.5e+G8III binary BR CMi = HD 61273 compared to those of other well studied semi-detached emission-line binaries
• Ultraviolet Spectropolarimetry: on the origin of rapidly rotating B stars
• Updated radial velocities and new constraints on the nature of the unseen source in NGC1850 BH1
• Search for Dormant Black Holes in Ellipsoidal Variables II. A Binary Modified Minimum Mass Ratio
• Fundamental stellar and accretion disc parameters of the eclipsing binary DQ Velorum
• Detecting Stripped Stars While Searching for Quiescent Black Holes