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WDJ220838.73+454434.04: a White Dwarf Companion in the AR Lacertae System
Abstract We present WDJ220838.73+454434.04 (hereafter WD2208+454), a wide, co-moving white dwarf companion to the eclipsing binary system, AR Lacertae. The companion was discovered through the Backyard Worlds: Planet 9 citizen science collaboration. It has a separation of 21.″9 on the sky from the central eclipsing pair, translating to a projected separation of ∼930 au. We present a review of the physical properties and orbital parameters of this new addition to the system.
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Award ID(s):
Publication Date:
NSF-PAR ID:
10352425
Journal Name:
Research Notes of the AAS
Volume:
6
Issue:
6
Page Range or eLocation-ID:
127
ISSN:
2515-5172
3. ABSTRACT We report the discovery of the closest known black hole candidate as a binary companion to V723 Mon. V723 Mon is a nearby ($d\sim 460\, \rm pc$), bright (V ≃ 8.3 mag), evolved (Teff, giant ≃ 4440 K, and Lgiant ≃ 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 All-Sky Automated Survey, Kilodegree Extremely Little Telescope, and Transiting Exoplanet Survey Satellite 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 $87.0^{\circ ^{+1.7^\circ }}_{-1.4^\circ }$, a mass ratio of q ≃ 0.33 ± 0.02, a companion mass of Mcomp = 3.04 ± 0.06 M⊙, a stellar radius of Rgiant = 24.9 ± 0.7 R⊙, and a giant mass of Mgiant = 1.00 ± 0.07 M⊙. We identify a likely non-stellar, diffuse veiling component with contributions in the B and V band of ${\sim }63{{\ \rm per\ cent}}$ and ${\sim }24{{\ \rm per\ cent}}$, respectively. The SED and the absence of continuum eclipses imply that the companion mass must be dominated by a compact object. We do observe eclipses of the Balmermore »