Double stars with wide separations in the AGK3 - II. The wide binaries and the multiple systems

TL;DR

This study measures radial velocities of common proper motion stars to identify wide binaries and analyze their separation distribution, revealing a log-normal pattern and insights into multiple system formation.

Contribution

It provides a bias-controlled sample of wide binaries, confirming their separation distribution follows a log-normal pattern and offering statistical insights into multiple system configurations.

Findings

Wide binaries follow a log-normal separation distribution.

Spectroscopic binaries among WBs are similar to those in field stars.

Quadruple systems align with the 'no correlation' hypothesis.

Abstract

A large observation programme was carried out to measure the radial velocities of the components of a selection of common proper motion (CPM) stars, in order to select the physical binaries. Eighty wide binaries (WBs) were detected, and 39 optical pairs were identified. Adding CPM stars with separations close enough to be almost certain they are physical, a "bias-controlled" sample of 116 wide binaries was obtained, and used to derive the distribution of separations from 100 to 30,000 au. The distribution obtained doesn't match the log-constant distribution, but is in agreement with the log-normal distribution. The spectroscopic binaries detected among the WB components were used to derive statistical informations about the multiple systems. The close binaries in WBs seem to be similar to those detected in other field stars. As for the WBs, they seem to obey the log-normal distribution of periods. The number of quadruple systems is in agreement with the "no correlation" hypothesis; this indicates that an environment conducive to the formation of WBs doesn't favor the formation of subsystems with periods shorter than 10 years.