Spectroscopy of the mysterious Be system FF Cam

TL;DR

This paper presents spectroscopic observations of FF Cam, revealing it as a binary system with a B-type primary and K-type secondary, exhibiting variable emission lines and radial velocities, indicating complex stellar interactions.

Contribution

The study provides the first detailed spectroscopic analysis confirming FF Cam as a binary system with a 7.785-day period and characterizes its spectral features and variability.

Findings

FF Cam is a binary with a 7.785-day orbital period.

The primary is a B-type star, secondary is K-type.

The system shows variable H-alpha emission and radial velocities.

Abstract

FF Cam is a variable star near the North celestial pole with hydrogen lines in emission. Its optical variability of ~0.3 mag was discovered by HIPPARCOS. The spectral type assigned to the star in SIMBAD is B9, but its position coincides with a ROSAT X-ray source. This suggests the presence of a high-temperature region in the system that could originate at or near a companion object. We undertook a spectroscopic monitoring of FF Cam since the beginning of 2012 and found an extremely variable H-alpha line profile as well as periodically variable radial velocities of numerous absorption lines. The main conclusion from our study is that FF Cam is a binary system with an orbital period of 7.785 days, a B-type primary and a K-type secondary component. We discuss the spectral features, their variations, and the nature of FF Cam.