Membership and Binarity of Red Giants in Open Clusters Determined by Photoelectric Radial Velocities

Star Clusters ◽  
1980 ◽  
pp. 361-362
Author(s):  
J.-C. Mermilliod ◽  
M. Mayor
Keyword(s):  
Open Clusters ◽  
Radial Velocities ◽  
Red Giants

scholarly journals Membership and Binarity of Red Giants in Open Clusters Determined by Photoelectric Radial Velocities

1980 ◽  
Vol 85 ◽  
pp. 361-362
Author(s):  
J.-C. Mermilliod ◽  
M. Mayor
Keyword(s):  
Open Clusters ◽  
Radial Velocities ◽  
Red Giants

An observing programme was started in the summer of 1977 to measure radial velocities of red giants in open clusters with the spectrovelocimeter “Coravel” (Baranne et al. 1979) attached to the 1 m telescope of the Geneva Observatory installed at the O.H.P. (France). 750 measurements for 160 stars in 30 open clusters north of −20°, with ages ranging from those of NGC 752 to Pleidades, have been obtained. The limiting magnitude is B = 12.5.

scholarly journals Non-linear seismic scaling relations

2018 ◽  
Vol 616 ◽  
pp. A104 ◽  
Author(s):  
T. Kallinger ◽  
P. G. Beck ◽  
D. Stello ◽  
R. A. Garcia
Keyword(s):  
Binary Systems ◽  
Open Clusters ◽  
Eclipsing Binaries ◽  
Probabilistic Methods ◽  
Frequency Separation ◽  
Scaling Relations ◽  
Distance Modulus ◽  
Red Giants ◽  
Eclipsing Binary ◽  
Non Linear

Context. In recent years the global seismic scaling relations for the frequency of maximum power, νmax ∝ g / √Teff, and for the large frequency separation, Δν ∝ √ρ¯, have drawn attention in various fields of astrophysics. This is because these relations can be used to estimate parameters, such as the mass and radius of stars that show solar-like oscillations. With the exquisite photometry of Kepler, the uncertainties in the seismic observables are small enough to estimate masses and radii with a precision of only a few per cent. Even though this seems to work quite well for main-sequence stars, there is empirical evidence, mainly from studies of eclipsing binary systems, that the seismic scaling relations systematically overestimate the mass and radius of red giants by about 15% and 5%, respectively. Various model-based corrections of the Δν-scaling reduce the problem but do not solve it. Aims. Our goal is to define revised seismic scaling relations that account for the known systematic mass and radius discrepancies in a completely model-independent way. Methods. We use probabilistic methods to analyse the seismic data and to derive non-linear scaling relations based on a sample of six red giant branch (RGB) stars that are members of eclipsing binary systems and about 60 red giants on the RGB as well as in the core-helium burning red clump (RC) in the two open clusters NGC 6791 and NGC 6819. Results. We re-examine the global oscillation parameters of the giants in the binary systems in order to determine their seismic fundamental parameters and we find them to agree with the dynamic parameters from the literature if we adopt non-linear scalings. We note that a curvature and glitch corrected Δνcor should be preferred over a local or average value of Δν. We then compare the observed seismic parameters of the cluster giants to those scaled from independent measurements and find the same non-linear behaviour as for the eclipsing binaries. Our final proposed scaling relations are based on both samples and cover a broad range of evolutionary stages from RGB to RC stars: g / √Teff = (νmax / νmax,⊙)1.0075±0.0021 and √ρ¯ = (Δνcor / Δνcor,⊙)[η − (0.0085 ± 0.0025) log2(Δνcor / Δνcor,⊙)]−1, where g, Teff, and ρ¯ are in solar units, νmax,⊙ = 3140 ± 5 μHz and Δνcor,⊙ = 135.08 ± 0.02 μHz, and η is equal to one in the case of RGB stars and 1.04 ± 0.01 for RC stars. Conclusions. A direct consequence of these new scaling relations is that the average mass of stars on the ascending giant branch reduces to 1.10 ± 0.03 M⊙ in NGC 6791 and 1.45 ± 0.06 M⊙ in NGC 6819, allowing us to revise the clusters’ distance modulus to 13.11 ± 0.03 and 11.91 ± 0.03 mag, respectively. We also find strong evidence that both clusters are significantly older than concluded from previous seismic investigations.

scholarly journals Red giants in open clusters

2008 ◽  
Vol 485 (1) ◽  
pp. 303-314 ◽  
Author(s):  
J. C. Mermilliod ◽  
M. Mayor ◽  
S. Udry
Keyword(s):  
Open Clusters ◽  
Red Giants

Stellar and molecular radial velocities for six young open clusters

1988 ◽  
Vol 95 ◽  
pp. 1122 ◽  
Author(s):  
Tianxing Liu ◽  
Kenneth A. Janes ◽  
T. M. Bania ◽  
Randy L. Phelps
Keyword(s):  
Open Clusters ◽  
Radial Velocities

Mass-losing red giants in open clusters

1987 ◽  
Vol 313 ◽  
pp. 743 ◽  
Author(s):  
M. Jura
Keyword(s):  
Open Clusters ◽  
Red Giants

scholarly journals A Determination of Secular Parallaxes of Reference Stars from Relative Proper Motions of Open Clusters

1970 ◽  
Vol 7 ◽  
pp. 74-76
Author(s):  
A. N. Deutsch
Keyword(s):  
Systematic Errors ◽  
Open Clusters ◽  
Radial Velocities ◽  
Proper Motions ◽  
The Mean

The determination of secular parallaxes of stars is usually based on meridian observations of proper motions of bright stars, this introducing known systematic errors. The mean parallaxes of stars can be obtained by means of radial velocities which are known for the bright stars. The more perspective method, the reference of stars to galaxies, is not applicable at low galactic latitudes.

scholarly journals Mass Loss from Red Giants in Old Open Clusters

1975 ◽  
Vol 173 (1) ◽  
pp. 223-229 ◽  
Author(s):  
T. G. Hawarden
Keyword(s):  
Mass Loss ◽  
Open Clusters ◽  
Red Giants
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