scholarly journals Can Evolution in Close Binaries Account for the Blue Stragglers in M67?

1992 ◽  
Vol 151 ◽  
pp. 473-474
Author(s):  
Alejandra A. E. Milone ◽  
David W. Latham ◽  
Robert D. Mathieu ◽  
Jon A. Morse ◽  
Robert J. Davis
Keyword(s):  
Open Cluster ◽  
Radial Velocities ◽  
Close Binaries ◽  
Similar Reduction ◽  
Blue Stragglers ◽  
The Past

For the past 9 years we have been monitoring the radial velocities of 13 blue stragglers in the old open cluster M67. For the 9 blue stragglers with rotational velocities no larger than about 100 km s−1 we have used the CfA digital speedometers to measure more than 500 radial velocities. To get reliable velocity correlations we use synthetic rotating templates computed from a grid of Kurucz model atmospheres. Four of the blue stragglers rotate too rapidly to allow successful velocity correlations with the CfA instruments. For three of these we have used a CCD spectrograph at Kitt Peak and similar reduction procedures (Morse et al. 1991.

scholarly journals Tidal Circularization Among the Close Binaries in M67

1992 ◽  
Vol 151 ◽  
pp. 471-472
Author(s):  
David W. Latham ◽  
Robert D. Mathieu ◽  
Alejandra A. E. Milone ◽  
Robert J. Davis
Keyword(s):  
Main Sequence ◽  
Open Cluster ◽  
Radial Velocities ◽  
Spectroscopic Binaries ◽  
Close Binaries ◽  
To Come ◽  
Mirror Telescope

In 1971 Roger Griffin and Jim Gunn began monitoring the radial velocities of most of the members brighter than the main-sequence turnoff in the old open cluster M67, primarily using the 200-inch Hale Telescope. In 1982 the torch was passed to Dave Latham and Bob Mathieu, who began monitoring many of the same stars with the 1.5-meter Tillinghast Reflector and the Multiple-Mirror Telescope on Mt. Hopkins. We have successively combined these two sets of data, plus some additional CORAVEL velocities kindly provided by Michel Mayor, to obtain 20 years of time coverage (e.g. Mathieu et al. 1986). Among the stars brighter than magnitude V = 12.7 we have already published orbits for 22 spectroscopic binaries (Mathieu et al. 1990). At Mt. Hopkins an extension of this survey to many of the cluster members down to magnitude V = 15.5 has already yielded thirteen additional orbital solutions, with the promise of many more to come.

scholarly journals Spectroscopic Binaries in the Open Cluster M67

1992 ◽  
Vol 135 ◽  
pp. 155-157 ◽  
Author(s):  
David W. Latham ◽  
Robert D. Mathieu ◽  
Alejandra A.E. Milone ◽  
Robert J. Davis
Keyword(s):  
Circular Orbit ◽  
Main Sequence ◽  
Open Cluster ◽  
Radial Velocities ◽  
Spectroscopic Binaries ◽  
Eccentric Orbit ◽  
Circular Orbits ◽  
Blue Stragglers ◽  
Short Period ◽  
Blue Straggler

AbstractFor almost 400 members of M67 we have accumulated about 5,000 precise radial velocities. Already we have orbital solutions for more than 32 spectroscopic binaries in M67. Many of these orbits were derived by combining the Palomar and CfA observations, thus extending the time coverage to more than 20 years. The distribution of eccentricity versus period shows evidence for tidal circularization on the main sequence. The transition from circular orbits is fairly clean. Excluding the blue stragglers, the first eccentric orbit has a period of 11.0 days, while the last circular orbit has a period of 12.4 days. For longer periods the distribution of eccentricity is the same as for field stars. The blue straggler S1284 has an eccentric orbit despite its short period of 4.2 days.

scholarly journals SOME REMARKS ON THE OPEN CLUSTER UPGREN 1 USING uvby − β PHOTOELECTRIC PHOTOMETRY

2019 ◽  
Vol 55 (2) ◽  
pp. 221-229 ◽  
Author(s):  
J. H. Peña ◽  
A. Rentería ◽  
H. Huepa ◽  
A. Pani
Keyword(s):  
Open Cluster ◽  
Radial Velocities ◽  
Photoelectric Photometry ◽  
The Past ◽  
Empirical Relations

The open cluster Upgren 1 presents peculiar features that in the past led to divergent opinions about its existence. In previous studies of other clusters, uvby − β photoelectric photometry has shown results in agreement with other techniques; therefore, the photometry obtained in the present work has been combined with data from previous studies to examine the brightest stars in the direction of the cluster. Analyzing the unreddened indexes, we found that all the stars are of late spectral types. Applying the empirical relations of Nissen (1987) to determine the reddening and, consequently, the unreddened indexes, we found that all but three are located at a distance of 123 ± 17 pc. The assigned membership in this study is in concordance with that of Upgren, Philip and Beaver (1982) obtained through radial velocities.

Radial Velocities, Binarity, and Kinematic Membership in the Open Cluster NGC 2516

2000 ◽  
Vol 119 (5) ◽  
pp. 2296-2302 ◽  
Author(s):  
Jorge Federico González ◽  
Emilio Lapasset
Keyword(s):  
Open Cluster ◽  
Radial Velocities

scholarly journals UOCS. IV. Discovery of diverse hot companions to blue stragglers in the old open cluster King 2

2021 ◽  
Vol 42 (2) ◽  
Author(s):  
Vikrant V. Jadhav ◽  
Sindhu Pandey ◽  
Annapurni Subramaniam ◽  
Ram Sagar
Keyword(s):  
Open Cluster ◽  
Blue Stragglers

scholarly journals X-Ray Observations of B-Emission Stars (Review Paper)

1987 ◽  
Vol 92 ◽  
pp. 291-308 ◽  
Author(s):  
E.P.J. van den Heuvel ◽  
S. Rappaport
Keyword(s):  
Review Paper ◽  
Circumstellar Disks ◽  
Close Binaries ◽  
Be Stars ◽  
X Ray ◽  
Blue Stragglers ◽  
Galactic Clusters ◽  
Be Star ◽  
Emission Stars ◽  
X Ray Binaries

Most evidence on X-ray emission from the vicinity of Be stars concerns the Be/X-ray binaries. Presently some 20 of these systems are known, making them the most numerous class of massive X-ray binaries. Evidence for the binary nature of these systems comes from (i) Doppler modulation of X-ray pulse periods, (ii) periodic X-ray flaring behavior, and (iii) correlated optical and X-ray variability. The correlation between X-ray pulse period and orbital period found by Corbet (1984) can potentially provide important information on the densities and velocities in the circumstellar disks of Be stars.Evolutionary models indicate that the Be/X-ray binaries represent a later stage in the evolution of normal close binaries with initial primary masses predominantly in the the range 8 to 15 M⊙ . These models indicate that also a class of slightly less massive Be star binaries should exist in which the compact companions are white dwarfs. Be-type blue stragglers in galactic clusters may be such systems.

scholarly journals Dynamics and Binary (Trans)formation in Globular Clusters

1996 ◽  
Vol 165 ◽  
pp. 377-388
Author(s):  
Piet Hut
Keyword(s):  
Globular Clusters ◽  
Stellar Dynamics ◽  
Diagnostic Tools ◽  
Reaction Products ◽  
Exchange Reactions ◽  
Blue Stragglers ◽  
The Past ◽  
X Ray Binaries ◽  
Triple Star ◽  
Made In

Globular clusters form ideal laboratories for studying the interactions between stellar evolution and stellar dynamics. In the past, highly exceptional systems such as X-ray binaries and later millisecond pulsars have provided us with useful diagnostic tools. However, the fate of the bulk of the more normal stars has remained less clear. At present, rapid progress is being made in our understanding of the distributions of normal stars and primordial binaries, as well as their most abundant reaction products: blue stragglers and binaries that are produced through exchange encounters with other single stars or binaries. The complexity of the network of exchange reactions is illustrated through some specific examples, such as a formation scenario for the hierarchical triple system containing the millisecond pulsar PSR B1620-26 in M4, the first triple star system ever detected in a globular cluster.

The oscillating blue stragglers in the open cluster M67

1992 ◽  
Vol 103 ◽  
pp. 1945 ◽  
Author(s):  
Ronald L. Gilliland ◽  
Timothy M. Brown
Keyword(s):  
Open Cluster ◽  
Blue Stragglers

scholarly journals A Triple Origin for Twin Blue Stragglers in Close Binaries

2019 ◽  
Vol 876 (2) ◽  
pp. L33 ◽  
Author(s):  
Simon Portegies Zwart ◽  
Nathan W. C. Leigh
Keyword(s):  
Close Binaries ◽  
Blue Stragglers

scholarly journals Star Cluster Simulations on HARP

1996 ◽  
Vol 174 ◽  
pp. 161-170 ◽  
Author(s):  
Sverre J. Aarseth
Keyword(s):  
Gravitational Radiation ◽  
Cluster Model ◽  
Open Cluster ◽  
Star Cluster ◽  
Peak Performance ◽  
Strong Interactions ◽  
Common Envelope ◽  
Blue Stragglers ◽  
New Formulation ◽  
Evolution Type

We describe some aspects of implementing star cluster simulations on HARP. The code NBODY4 employs the Hermite scheme with hierarchical block-steps for direct integration. The algorithms have been optimized for parallel processing with the eight pipeline HARP-2 delivering a peak performance of about 1.7 Gflops for N = 104 particles. Hard binaries are studied by KS regularization which also uses the Hermite scheme, whereas strong interactions between 3–5 particles are treated by chain regularization. Astrophysical processes modelled include mass loss by stellar evolution, two-body tidal interaction, Roche lobe mass transfer, common envelope evolution, magnetic braking and gravitational radiation. Consistent values of stellar radii and evolution type are obtained by fast look-up. A new formulation of collision outcomes yields blue stragglers and other exotic objects. Some recent results for an open cluster model are presented.

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