The multiple nature of CC Com: one of the ultra-short orbital period late-type contact binary systems

TL;DR

This paper investigates the complex multiple system CC Com, revealing additional distant companions and deriving detailed orbital and physical parameters through combined light curve and radial velocity analysis, advancing understanding of ultra-short period contact binaries.

Contribution

It provides the first detailed analysis of CC Com as a multiple system with three orbiting objects, including new orbital parameters and physical characteristics derived from combined observational data.

Findings

Discovery of two additional objects orbiting CC Com with periods of about 8 years and 100 years.

Precise orbital and physical parameters of the binary components and companions.

Discussion of the evolutionary status of CC Com and its components.

Abstract

The study of very short-period contact binaries provides an important laboratory in which the most important and problematic astrophysical processes of stellar evolution take place. Short-period contact systems, such as CC Com are particularly important for binary evolution. Close binary systems, especially those with multiple system members, have significant period variations, angular momentum loss mechanisms predominance, and pre-merger stellar evolution, making them valuable astrophysical laboratories. In this study, observations of CC Com, previously reported as a binary system, and new observations from the T\"UB\.ITAK National Observatory (TUG) and the space-based telescope TESS have revealed that there is a third object with a period of about eight years and a fourth object with a period of about a century orbiting the binary system. From simultaneous analysis of all available light curves and radial velocities, the sensitive orbital and physical parameters of the system components are derived. The orbital parameters of the components are P$_{\rm A}=0.221\pm0$ days, P$_{\rm B}=7.9\pm0.1$ yr, P$_{\rm C}=98\pm5$ yr, $e_3$ = 0.06, $e_4$ = 0.44 and the physical parameters as M$_{\rm A1}=0.712\pm0.009$ M$_{\odot}$, M$_{\rm A2}=0.372\pm0.005$ M$_{\odot}$, $m_{B;i'=90^\circ}$=0.074 M$_{\odot}$, $m_{C;i'=90^\circ}$=0.18 M$_{\odot}$, R$_{\rm A1}=0.693\pm0.006$ R$_{\odot}$, R$_{\rm A2}=0.514\pm0.005$ R$_{\odot}$, L$_{\rm A1}$ = 0.103 L$_\odot$, L$_{\rm A2}$ = 0.081 L$_\odot$. Finally, the evolutionary status of the multiple system CC Com and its component stars is discussed.