BRITE nascent binaries

TL;DR

This paper reviews the current understanding of nascent binaries with very low mass ratios, highlighting their significance in astrophysics, and characterizes two new such systems using data from the BRITE satellite.

Contribution

It summarizes existing knowledge of Galactic nascent binaries and introduces two newly characterized systems, c2 Sco and V390 Pup, based on BRITE satellite data.

Findings

Identification of two new nascent binaries, c2 Sco and V390 Pup.

Characterization of their photometric properties and irradiation effects.

Enhanced understanding of low-mass ratio binary formation.

Abstract

Nascent binaries (NBs) are binary systems with very low mass ratios, less than ~0.2, in which the more massive component is an O- or B-type main-sequence star, while the secondary is a star contracting onto the main sequence. NBs are of interest because they can help to understand the formation of small-mass ratio systems and shed light on the origin of low-mass X-ray binaries, millisecond pulsars and type Ia supernovae. In photometry, short-period NBs show a strong irradiation effect due to the large difference between the effective temperatures of the components and the strong irradiation of a cool secondary by a hot primary. In spectroscopy, they usually appear as single-lined spectroscopic binaries. In the present paper, we summarize the status of our knowledge of Galactic nascent binaries and characterize two new members of this group, c2 Sco and V390 Pup, for which photometric data were obtained by the BRIght Target Explorer (BRITE) nano-satellite mission.