Low-mass visual companions to nearby G-dwarfs

TL;DR

This study conducts a comprehensive survey of wide visual companions to nearby G-dwarf stars using 2MASS data, identifying new companions and analyzing their frequency and mass ratio distribution to improve understanding of stellar multiplicity.

Contribution

It provides the first complete census of wide visual companions to G-dwarfs, including newly identified low-mass stellar companions, and refines the companion frequency and mass ratio distribution.

Findings

Companion frequency is approximately 0.13 per decade of separation.

Mass ratio distribution is nearly uniform with a power-law index near zero.

Confirmed the presence of wide companions and reduced background star contamination.

Abstract

Complete census of wide visual companions to nearby G-dwarf stars can be achieved by selecting candidates from the 2MASS Point-Source Catalog and checking their status by second-epoch imaging. Such data are obtained for 124 candidates with separations up to 20", 47 of which are shown to be new physical low-mass stellar companions. A list of visual binaries with G-dwarf primaries is produced by combining newly found companions with historical data. Maximum likelihood analysis leads to the companion frequency of 0.13+-0.015 per decade of separation. The mass ratio is distributed almost uniformly, with a power-law index between -0.4 and 0. The remaining uncertainty in the index is related to modeling of the companion detection threshold in 2MASS. These findings are confirmed by alternative analysis of wider companions in 2MASS, removing the contamination by background stars statistically. Extension of this work will lead to a complete detection of visual companions - a necessary step towards reaching unbiased multiplicity statistics over the full range of orbital periods and, eventually, understanding the origin of multiple systems.