On the nature of the Be star HR 7409 (7 Vul)

TL;DR

This paper investigates the binary nature and evolutionary history of the Be star HR 7409 (7 Vul), analyzing spectroscopic data to determine its companion's properties and possible formation scenarios.

Contribution

It provides new spectroscopic measurements and explores different evolutionary scenarios for the binary system involving HR 7409.

Findings

Binary period of 69 days determined

Companion mass estimated at 0.5-0.8 solar masses

Possible companion types include K V star, horizontal-branch star, or white dwarf

Abstract

HR 7409 (7 Vul) is a newly identified Be star possibly part of the Gould Belt and is the massive component of a 69-day spectroscopic binary. The binary parameters and properties of the Be star measured using high-dispersion spectra obtained at Ondrejov Observatory and at Rozhen Observatory imply the presence of a low mass companion (~ 0.5-0.8 M_sun). If the pair is relatively young (<50-80 Myr), then the companion is a K V star, but, following another, older evolutionary scenario, the companion is a horizontal-branch star or possibly a white dwarf star. In the latter scenario, a past episode of mass transfer from an evolved star onto a less massive dwarf star would be responsible for the peculiar nature of the present-day, fast-rotating Be star.