Astronomy and Astrophysics – Astrophysics
Scientific paper
2000-06-27
Astronomy and Astrophysics
Astrophysics
20 pages, 4 figures, to appear in October 2000 AJ
Scientific paper
10.1086/301569
We have analyzed high-resolution spectra of relatively cool blue stragglers and main sequence turnoff stars in the old open cluster M67 (NGC 2682). We attempt to identify blue stragglers whose spectra are least contaminated by binary effects (contamination by a binary companion or absorption by circumstellar material). These ``best'' stragglers have metallicities ([Fe/H] = -0.05) and abundance ratios of the blue stragglers are not significantly different from those of the turnoff stars. Based on arguments from hydrodynamical models of stellar collisions, we assert that the current upper limits for the lithium abundances of all blue stragglers observed in M67 (by us and others) are consistent with no mixing during the formation process, assuming pre-main sequence and main sequence depletion patterns observed for M67 main sequence stars. We discuss composition signatures that could more definitively distinguish between blue straggler formation mechanisms in open cluster stars. We confirm the spectroscopic detection of a binary companion to the straggler S 1082. From our spectra, we measure a projected rotational speed of 90+/-20 km/sec for the secondary, and find that its radial velocity varies with a peak-to-peak amplitude of ~ 25 km/sec. Because the radial velocities do not vary with a period corresponding to the partial eclipses in the system, we believe this system is currently undergoing mass transfer. In addition we present evidence that S 984 is a true blue straggler (and not an unresolved pair). If this can be proven, our detection of lithium may indicate a collisional origin.
Sandquist Eric
Shetrone Matthew
No associations
LandOfFree
Spectroscopy of Blue Stragglers and Turnoff Stars in M67 (NGC 2682) does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Spectroscopy of Blue Stragglers and Turnoff Stars in M67 (NGC 2682), we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spectroscopy of Blue Stragglers and Turnoff Stars in M67 (NGC 2682) will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-489762