scholarly journals Multiplicity of Solar-Type Stars

1977 ◽  
Vol 33 ◽  
pp. 47-51
Author(s):  
Helmut A. Abt
Keyword(s):  
Proper Motion ◽  
Stellar Mass ◽  
Spectroscopic Binaries ◽  
Cube Root ◽  
Bright Field ◽  
Mass Distributions ◽  
Root Relation ◽  
Median Period ◽  
Solar Type

AbstractA systematic search for binaries in a sample of 123 bright field stars of types F3-G2 IV or V is described. Combination of the results for 25 newly discovered spectroscopic binaries with those of 21 spectroscopic, 23 visual, and 25 common-proper-motion pairs previously known brings to 88 the total number of companions identified in the sample. The distribution of the 88 periods shows a single maximum; the median period is 14 years.The frequencies of singles: doubles: triples: quadruples are found to be 42: 46: 9: 2. Less than half of the stars are thus observed to be single. Estimates of the completeness of this search lead to a determination of the number of systems missed and to a determination of their secondary masses.Analysis of the secondary-mass distributions, observed and predicted from completeness estimates, indicates the existence of two types of binaries.For systems with periods less than about 100 years, the distribution of secondaries varies with the cube-root of the secondary mass. These systems must be the result of fission. Two-thirds of their primaries have companions of stellar mass. Extrapolation of the cube-root relation implies that the remaining one-third of the primaries have non-stellar secondaries, i.e., close companions whose masses are less than 0.07 solar masses.For systems with periods larger than roughly 100 years the distribution of secondaries follows that given by the van Rhijn function. They must be the result of condensations that contracted separately but are bound gravitationally. Roughly three-fourths of all primaries in the sample have such distant companions, all of which are likely to be themselves close fission-systems. Evidently single stars are rare among solar-type dwarfs.

Large-scale Motion of Solar Filaments

2000 ◽  
Vol 179 ◽  
pp. 205-208
Author(s):  
Pavel Ambrož ◽  
Alfred Schroll
Keyword(s):  
Magnetic Flux ◽  
Proper Motion ◽  
Time Scale ◽  
Large Scale ◽  
Accuracy Of Measurements ◽  
Solar Filaments ◽  
General Movement ◽  
Scale Motion ◽  
Velocity Scatter

AbstractPrecise measurements of heliographic position of solar filaments were used for determination of the proper motion of solar filaments on the time-scale of days. The filaments have a tendency to make a shaking or waving of the external structure and to make a general movement of whole filament body, coinciding with the transport of the magnetic flux in the photosphere. The velocity scatter of individual measured points is about one order higher than the accuracy of measurements.

scholarly journals PTPS Candidate Exoplanet Host Star Radii Determination with CHARA Array

2011 ◽  
Vol 7 (S282) ◽  
pp. 203-204
Author(s):  
Paweł Zieliński ◽  
Martin Vaňko ◽  
Ellyn Baines ◽  
Andrzej Niedzielski ◽  
Aleksander Wolszczan
Keyword(s):  
Effective Temperature ◽  
Critical Parameter ◽  
Spectroscopic Analysis ◽  
Evolutionary Model ◽  
Stellar Mass ◽  
Surface Temperatures ◽  
Penn State ◽  
Chara Array ◽  
Model Dependency

AbstractWe propose to measure the radii of the Penn State - Toruń Planet Search (PTPS) exoplanet host star candidates using the CHARA Array. Stellar radii estimated from spectroscopic analysis are usually inaccurate due to indirect nature of the method and strong evolutionary model dependency. Also, the so-called degeneracy of stellar evolutionary tracks due to convergence of many tracks in the giant branch decreases the precision of such estimates. However, the radius of a star is a critical parameter for the calculation of stellar luminosity and mass, which are often not well known especially for giants. With well determined effective temperature (from spectroscopy) and radius, the luminosity may be calculated precisely. In turn also stellar mass may be estimated much more precisely. Therefore, direct radii measurements increase precision in the determination of planetary candidates masses and the surface temperatures of the planets.

scholarly journals Galactic Kinematics on the Basis of Modern Proper Motion Data

1995 ◽  
Vol 166 ◽  
pp. 217-226
Author(s):  
M. Miyamoto
Keyword(s):  
High Precision ◽  
Proper Motion ◽  
Galactic Kinematics ◽  
Dark Halo ◽  
Motion Data ◽  
Structure And Dynamics ◽  
The Galaxy ◽  
Galactic Astronomy ◽  
Astrometric Data

An accumulation of high precision astrometric data in conjunction with high-precision monitoring of the Earth's orientation, motivates “Galactic Astronomy”. As regards local kinematics, all of the three components of both the vorticity and the shear of stars can be completely determined, in addition to the velocity ellipsoid. We can now be released from the constraint of the “axisymmetric” galaxy. The determination of the proper motion of the LMC will be crucial to understanding the global structure and dynamics of the Galaxy with the dark halo and MACHO's motions.

Spectroscopic Binaries in the Halo

1992 ◽  
Vol 135 ◽  
pp. 158-160 ◽  
Author(s):  
David W. Latham ◽  
Tsevi Mazeh ◽  
Robert P. Stefanik ◽  
Robert J. Davis ◽  
Bruce W. Carney ◽  
...  
Keyword(s):  
Proper Motion ◽  
Main Sequence ◽  
Radial Velocities ◽  
Spectroscopic Binaries ◽  
Variable Velocity ◽  
Short Period ◽  
The Galaxy ◽  
Elliptical Orbits

AbstractFor almost 1500 stars in the Carney-Latham survey of proper-motion stars we have accumulated about 20,000 precise radial velocities. Already we have orbital solutions for more than 150 spectroscopic binaries in this sample, and about 100 additional binary candidates with variable velocity. We find that among the metal-poor halo field stars in this sample the frequency of short-period spectroscopic binaries is indistinguishable from that of the disk. The distribution of eccentricity versus period shows evidence for tidal circularization on the main sequence. For the binaries more metal poor than [m/H] = −1.6 there is a clean transition from circular to elliptical orbits at a period of about 19 days. For longer periods the distribution of eccentricity is the same as for stars in the disk of the Galaxy.

scholarly journals Statistical Properties of an Unbiased Sample of F7-K Binaries: Towards The Long-Period Systems

2004 ◽  
Vol 191 ◽  
pp. 28-32 ◽  
Author(s):  
A. Eggenberger ◽  
J.-L. Halbwachs ◽  
S. Udry ◽  
M. Mayor
Keyword(s):  
Main Sequence ◽  
Equal Mass ◽  
Statistical Properties ◽  
Spectroscopic Binaries ◽  
Mass Ratio ◽  
Long Period ◽  
Period Distribution ◽  
Solar Type ◽  
Flat Distribution ◽  
Visual Binaries

AbstractWe have undertaken a new investigation of the statistical properties of main-sequence binaries, which is a revision and extension of the Duquennoy & Mayor survey of solar-type stars. The analysis has been divided into two parts: the spectroscopic binaries with periods shorter than 10 years, and the long-period systems including visual binaries and common proper motion pairs. In this contribution we present preliminary results regarding the intrinsic mass ratio and period distributions of visual binaries. Our results are strongly limited by small-number statistics, but when combined with the ones found for the spectroscopic binaries, the following results are obtained: (i) the excess of equal-mass binaries, if still present, is less important for long-period systems than for the binaries with P < 50 days; (ii) the period distribution is inconsistent with a flat distribution.

A survey of proper motion stars. XI - Orbits for the second 40 spectroscopic binaries

1992 ◽  
Vol 104 ◽  
pp. 774 ◽  
Author(s):  
David W. Latham ◽  
Tsevi Mazeh ◽  
Robert P. Stefanik ◽  
Robert J. Davis ◽  
Bruce W. Carney ◽  
...  
Keyword(s):  
Proper Motion ◽  
Spectroscopic Binaries
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