The shortest period field contact binary

TL;DR

This paper presents photometric and spectroscopic analysis of the shortest period contact binary GSC 01387-00475, confirming the sharp period cutoff in contact binaries and discussing its unique characteristics.

Contribution

It provides detailed observational data for GSC 01387-00475, extending the known period limit for contact binaries and analyzing its unique low-inclination and companion effects.

Findings

The binary has an orbital period of 0.2178 days.

The system's light variability is reduced due to low inclination and a third star.

It supports the existence of a sharp period cutoff in contact binaries.

Abstract

Photometric and spectroscopic results for the contact binary GSC 01387-00475 (ASAS 083128+1953.1) are presented. The existence of this binary with the orbital period of P = 0.2178 d strengthens the argument that the cut-off of the period distribution for contact binaries - until now defined by CC Comae - is very sharp. The only case of a still shorter period is known in a globular cluster where more compact contact configurations are in fact expected. While the spectroscopic orbit of GSC 01387-00475 is well defined, the low orbital inclination of the binary and the presence of a spectroscopic companion contributing about 1/3 of the total light conspire to reduce the photometric variability to ~0.09 mag. The photometric data are currently inadequate to identify the source of the small amplitude (0.02 - 0.03 mag) intrinsic variability of the system.