The Binary INformation from Open Clusters Using SEDs (BINOCS) Project: Reliable Photometric Mass Determinations of Binary Star Systems in Clusters

TL;DR

The BINOCS project introduces a new photometric method using spectral energy distributions to reliably determine binary star system masses in open clusters across a wide mass range, improving binary detection and characterization.

Contribution

This paper presents a novel SED-based technique for accurate binary and single star mass determination in open clusters, extending detection capabilities to lower mass stars.

Findings

Successfully applied to four open clusters with deep infrared data.

Determined binary fractions as functions of age, location, and metallicity.

Provided new catalogs with component masses for unresolved binaries.

Abstract

We introduce a new binary detection technique, Binary INformation from Open Clusters using SEDs (binocs), which we show is able to determine reliable stellar multiplicity and masses over a much larger mass range than current approaches. This new technique determines accurate component masses of binary and single systems of the open clusters main sequence by comparing observed magnitudes from multiple photometric filters to synthetic star spectral energy distributions (SEDs) allowing systematically probing the binary population for low mass stars in clusters for 8 well-studied open clusters. We provide new deep, infrared photometric catalogs (1.2 - 8.0 microns) for the key open clusters NGC 1960 (M36), NGC 2099 (M37), NGC 2420, and NGC2682 (M67), using observation from NOAO/NEWFIRM and Spitzer}/IRAC. Using these deep multi-wavelength catalogs, the binocs method is applied to these clusters to determine accurate component masses for unresolved cluster binaries. We explore binary fractions as a function of cluster age, Galactic location and metallicity.