A spectroscopic study of the blue stragglers in M67

TL;DR

This spectroscopic study of 24 blue straggler stars in M67 reveals their diverse temperature and gravity profiles, confirming their main-sequence nature through detailed spectral analysis.

Contribution

The paper provides a comprehensive spectroscopic analysis of all blue stragglers in M67 using calibrated spectra and dual comparison methods, offering new insights into their physical properties.

Findings

Blue stragglers in M67 have Teff between 5600 and 12600 K.

Surface gravities are consistent with main-sequence stars.

Spectral properties support the main-sequence classification of these BSs.

Abstract

Based on spectrophotometric observations from the Guillermo Haro Observatory (Cananea, Mexico), a study of the spectral properties of the complete sample of 24 blue straggler stars (BSs) in the old Galactic open cluster M67 (NGC 2682) is presented. All spectra, calibrated using spectral standards, were recalibrated by means of photometric magnitudes in the Beijing-Arizona-Taipei-Connecticut system, which includes fluxes in 11 bands covering ~3500-10000 A. The set of parameters was obtained using two complementary approaches that rely on a comparison of the spectra with (i) an empirical sample of stars with well-established spectral types and (ii) a theoretical grid of optical spectra computed at both low and high resolution. The overall results indicate that the BSs in M67 span a wide range in Teff(~ 5600 -12600 K) and surface gravities that are fully compatible with those expected for main-sequence objects (log g = 3.5 -5.0 dex).