A chemical study of M67 candidate blue stragglers and evolved blue stragglers observed with APOGEE DR14

Abstract

Within the variety of objects populating stellar clusters, blue straggler stars (BSSs) are among the most puzzling ones. BSSs are commonly found in globular clusters, but they are also known to populate open clusters of the Milky Way. Two main theoretical scenarios (collisions and mass transfer) have been suggested to explain their formation, although finding observational evidence in support of either scenario represents a challenging task. Among the APOGEE observations of the old open cluster M67, we found 8 BSS candidates known from the literature and two known evolved BSSs. We carried out a chemical analysis of 3 BSS candidates and of the 2 evolved BSSs out of the sample and found that the BSS candidates have surface abundances similar to those of stars on the main-sequence turn-off of M67. Especially the absence of any anomaly in their carbon abundances seems to support a collisional formation scenario for these stars. Furthermore, we note that the abundances of the evolved BSSs S1040 and S1237 are consistent with the abundances of the red clump stars of M67. In particular, they show a depletion in carbon by $\sim 0.25$ dex, which could be either interpreted as the signature of mass transfer or as the product of stellar evolutionary processes. Finally, we summarise the properties of the individual BSS stars observed by APOGEE, as derived from their APOGEE spectra and/or from information available in the literature.

16 pages, 11 figures, accepted by MNRAS

References in corpus (19)

• Gaia Data Release 2. Summary of the contents and survey properties
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• Gaia Data Release 2: The astrometric solution
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• The K2 Mission: Characterization and Early results
• The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment
• A new implementation of the infrared flux method using the 2MASS catalogue
• Mergers and Obliquities in Stellar Triples
• Dynamical age differences among coeval star clusters as revealed by blue stragglers
• WIYN Open Cluster Study XXXII: Stellar Radial Velocities in the Old Open Cluster NGC 188
• Discovery of Carbon/Oxygen depleted Blue Straggler Stars in 47 Tucanae: the chemical signature of a mass-transfer formation process
• The blue stragglers formed via mass transfer in old open clusters
• The end of the white dwarf cooling sequence in M 67
• The K2 M67 Study: An Evolved Blue Straggler in M67 from K2 Mission Asteroseismology
• MOST satellite photometry of stars in the M67 field: Eclipsing binaries, blue stragglers and delta-Scuti variables
• Observing the products of stellar evolution in the old open cluster M67 with APOGEE
• Spinning like a Blue Straggler: the population of fast rotating Blue Straggler stars in Omega Centauri
• Blue Straggler Stars in Globular Clusters: a powerful tool to probe the internal dynamical evolution of stellar systems
• A spectroscopic study of the blue stragglers in M67

Cited by in corpus (13)

• The Gaia-ESO survey: mapping the shape and evolution of the radial abundance gradients with open clusters
• UVIT Open Cluster Study. II. Detection of extremely low mass white dwarfs and post-mass transfer binaries in M67
• UVIT Open Cluster Study. I. Detection of a White Dwarf Companion to a Blue Straggler in M67: Evidence of Formation through Mass Transfer
• UOCS.VI. UVIT/AstroSat detection of low-mass white dwarf companions to 4 more blue stragglers in M67
• UOCS. III. UVIT catalogue of open clusters with machine learning based membership using \textit{Gaia} EDR3 astrometry
• UVIT/ASTROSAT studies of Blue Straggler stars and post-mass transfer systems in star clusters: Detection of one more blue lurker in M67
• The blue straggler population of the old open cluster Berkeley 17
• The longevity of the oldest open clusters: Structural parameters of NGC 188, NGC 2420, NGC 2425, NGC 2682, NGC 6791, NGC 6819
• Discovery of double BSS sequences in the old Galactic open cluster Berkeley 17
• Asteroseismic Study of Subgiants and Giants of the Open Cluster M67 using Kepler/K2: Expanded Sample and Precise Masses
• M67 Blue Stragglers with High-resolution Infrared Spectroscopy
• Photometric variability of blue straggler stars in M67 with TESS and K2
• Beryllium: The smoking gun of a rejuvenated star