Fragile Binary Candidates in the SDSS DR8 spectroscopic archive

TL;DR

This paper catalogs 80 wide fragile binary star candidates from SDSS DR8, analyzing their properties and suggesting they can survive for over 8 billion years based on activity and age indicators.

Contribution

It provides the first comprehensive catalog of wide fragile binary candidates with detailed spectroscopic and photometric analysis.

Findings

Binary candidates have metallicity around -0.5 dex.

All pairs are members of the galactic disk.

Wide pairs can survive for more than 8 Gyr.

Abstract

We present a catalog of 80 very wide fragile binary candidates (projected separations > 10000 AU) from the SDSS DR8 spectral archive. The pairs were selected based on proper motion, radial velocity, metallicity and photometric parallax criteria. The angular separations of these pairs range from 3" to 250". The peak in the metallicity distribution of these pairs is about -0.5 dex of solar metallicity. Space motions and reduced proper motion diagrams indicate all these pairs are members of the disk. The chromospheric activity index SHK of each component in 38 binary candidates having spectra of high signal-to-noise ratio and member stars of three open clusters (NGC2420, M67 and NGC6791) were measured. The SHK vs. color relation for these binary candidates is consistent with the trend seen in these open clusters. The ages implied by this relation suggest that fragile wide pairs can survive longer than 8 Gyr.