The Close Binary V486 Carinae

TL;DR

This study analyzes the close binary V486 Carinae using satellite and ground-based photometry and spectroscopy, revealing system parameters, light variation features, and potential additional stellar components.

Contribution

It provides new parameter estimates and photometric insights for V486 Car, including the detection of a possible low-mass tertiary companion.

Findings

Masses: M1=2.1, M2=0.4 solar masses

Distance: 162 parsecs

Detection of a low-mass star in orbit around the binary

Abstract

The hitherto neglected close binary V486 Car is studied with the aid of newly applied satellite photometry (HIPPARCOS and TESS), high dispersion spectrometry (HERCULES) and ground-based B and V photometry. While the sinusoidal light variations are suggestive of a near-contact system, the stars have only shallow eclipse, so highly confident parametrization becomes challenging. We find: $M_1 = 2.1 \pm 0.1$, $M_2 = 0.4 \pm 0.1$; $R_1 = 3.20 \pm 0.02$, $R_2 = 1.48 \pm 0.01$; (${\odot}$); $T_{e1} = 10000 \pm 500$, $T_{e2} = 6200 \pm 200$ (K); distance = 162 $\pm$ 12 (pc). New times of minima for V486 Car have been examined, including recent observations from TESS. The role of the relatively significant O'Connell effect is examined. As well as the conspicuous asymmetry from the main effect of about 0.036 mag (V), a jitter, with amplitude of about 0.005 V mag and quasi-period of order $\sim$ 10 d is noticed. There is a tendency for such photometric excursions at one maximum to precede those at the other. As well, the O -- C data indicate the presence of a low mass star $\sim$0.3 M$_{\odot}$ in an orbit separated by a few AU from the close binary. More accurate and plentiful spectroscopic data would be requisite for further investigations. A brief discussion reviews possible approaches to understanding the system in the context of near-contact binary scenarios.