The white dwarf binary pathways survey - II. Radial velocities of 1453 FGK stars with white dwarf companions from LAMOST DR4

TL;DR

This study analyzes a large sample of WD+FGK binary stars using LAMOST data to identify close systems and assess their potential as Type Ia supernova progenitors, highlighting the importance of high-resolution spectroscopy.

Contribution

It significantly expands the known sample of WD+FGK binaries and provides radial velocity measurements crucial for identifying potential supernova progenitors.

Findings

Identified 24 close binary systems with significant radial velocity variations.

Found approximately 10% of WD+FGK systems are close binaries.

Highlighted the need for high-resolution spectroscopy to detect double-degenerate SNIa progenitors.

Abstract

We present the second paper of a series of publications aiming at obtaining a better understanding regarding the nature of type Ia supernovae (SNIa) progenitors by studying a large sample of detached F, G and K main sequence stars in close orbits with white dwarf companions (i.e. WD+FGK binaries). We employ the LAMOST (Large Sky Area Multi-Object Fibre Spectroscopic Telescope) data release 4 spectroscopic data base together with GALEX (Galaxy Evolution Explorer) ultraviolet fluxes to identify 1,549 WD+FGK binary candidates (1,057 of which are new), thus doubling the number of known sources. We measure the radial velocities of 1,453 of these binaries from the available LAMOST spectra and/or from spectra obtained by us at a wide variety of different telescopes around the globe. The analysis of the radial velocity data allows us to identify 24 systems displaying more than 3sigma radial velocity variation that we classify as close binaries. We also discuss the fraction of close binaries among WD+FGK systems, which we find to be ~10 per cent, and demonstrate that high-resolution spectroscopy is required to efficiently identify double-degenerate SNIa progenitor candidates.