We report the discovery of the closest known black hole candidate as a binary companion to V723 Mon.
V723 Mon is a nearby (d∼460pc), bright (V≃8.3~mag), evolved (Teff≃4440~K, and L≃173 L☉) red giant in a high mass function, f(M)=1.72±0.01 M☉, nearly circular binary (P=59.9 d, e≃0). V723 Mon is a known variable star, previously classified as an eclipsing binary, but its light curves are those of a nearly edge-on ellipsoidal variable. Detailed models of the light curves constrained by the period, radial velocities and stellar temperature give an inclination of 87∘±2∘, a mass ratio of q≃0.33±0.02, a companion mass of M=3.04±0.06 M☉, a stellar radius of R=24.9±0.7 R☉, and a giant mass of M=1.00±0.07 M☉. The simplest explanation for the massive companion is a single compact object, most likely a black hole in the “mass gap”.
Artist’s illustration of V723 Mon:
Illustration created by Lauren Fanfer, College of Arts and Sciences at The Ohio State University
Animations (with orbits shown, blue: black hole, orange: red giant):
The following videos illustrate the orbits of the non-interacting black hole (orbit traced in blue) and the red giant (orbit traced in orange) around their common center of mass. This binary system completes one orbit in around 60 days. Due to the gravity of the black hole, the shape of the red giant is tidally distorted from a spherical shape into something that looks more like a football (see the artist’s illustration).
Credits: Andrew Schneider, ASAS-SN/ASC-Tech, The Ohio State University
Credits: Andrew Schneider, ASAS-SN/ASC-Tech, The Ohio State University
Animations (without orbits):
Credits: Andrew Schneider, ASAS-SN/ASC-Tech, The Ohio State University
Credits: Andrew Schneider, ASAS-SN/ASC-Tech, The Ohio State University
Downloads: