WIYN Open Cluster Study. XC. Radial-velocity Measurements and Spectroscopic Binary Orbits in the Open Cluster NGC 2506

TL;DR

This study provides extensive radial-velocity data and binary star orbital solutions for the open cluster NGC 2506, revealing its binary frequency, stellar distribution, and properties of blue and yellow stragglers over 41 years.

Contribution

It offers the first comprehensive radial-velocity survey of NGC 2506, including orbital parameters for 49 binaries and analysis of stellar populations, enhancing understanding of cluster dynamics and binary evolution.

Findings

Binary frequency for periods <10^4 days is 35%

Identified 49 binary orbits with periods from 1 to 7,580 days

At least 64% of blue stragglers are in binaries

Abstract

NGC 2506 is a rich, intermediate-age (2.0 Gyr), metal-poor ([Fe/H] $\sim$ -0.2) open cluster. This work presents the results of 12,157 spectroscopic radial-velocity measurements of 2,442 stars in the NGC 2506 field over 41 years, made as part of the WIYN Open Cluster Study. Radial-velocity measurements are complete for the population of proper-motion member stars brighter than a Gaia G magnitude of 15.5, in which 320 proper-motion and radial-velocity cluster members were identified. Within the observation limit of G $<$ 16.5, 469 proper-motion and radial-velocity members were identified. This work reports on the characteristics of NGC 2506, including projected spatial distribution, radial-velocity dispersion, and virial mass. This work also presents orbital solutions for 49 binary members with periods between 1 and 7,580 days. NGC 2506 has an incompleteness-corrected binary frequency for binaries with periods less than $10^4$ days of $35 \pm 5$%. This work also discusses in detail the 14 blue stragglers stars of NGC 2506$\unicode{x2014}$finding at least 64 $\pm$ 21% to be in binaries, 5 yellow straggler stars, and several other stars of note.