Astronomy and Astrophysics – Astronomy
Scientific paper
Oct 1990
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1990aj....100.1223f&link_type=abstract
Astronomical Journal (ISSN 0004-6256), vol. 100, Oct. 1990, p. 1223-1238. Research supported by CNRS.
Astronomy and Astrophysics
Astronomy
12
Astronomical Photography, Galactic Rotation, Stellar Magnitude, Stellar Motions, Classifications, Color-Magnitude Diagram, Radial Velocity, Space Surveillance, Velocity Distribution
Scientific paper
Proper motion and B - V color index have been derived from photographic surveys for a set of 3 × 104 stars in the blue apparent magnitude range 9.5-12.5 along almost a quarter of the galactic meridian (lII = 45°,bII, (lII ≥ + 30°) and ((lII = 225°,bII ≥ +80°). One star out of three has a significant tangential velocity larger than 0.02 arcsec per year. A set of 104 stars with an annual proper-motion range of 0.02- 0.20 arcsec was used to calibrate the reduced proper motion as function of the absolute magnitude for Pop. I and Pop. II standard photometric sequences. Two stellar systems of 5 × l03 stars each were segregated by the Pop. I and Pop. II ridge lines in the observed color-magnitude diagram. The derived standard solar motion was typical for F and G dwarfs. The velocity components (U, V) for 3 × 103 stars observed in a a radius north galactic polar cap provided a way of estimating the velocity dispersion in the galactic plane of 20 km s-1 for the stellar system segregated by the Pop. I color-magnitude sequences and of 70 km s-1 the system segregated by the Pop. II sequences. The velocity dispersion increased with the altitude the galactic plane of 0.18 km s-1 pc-1 for the kinematically cooler system and of 0.03 km s-1 pc-1 for the hotter system. Classification into two stellar systems has been applied to a set of 106 stars in the 1-31 northern declination zone and in the 9.5-12.5 blue apparent magnitude range. One star out of four has a significant annual proper motion of 0.02-0.20 arcsec and distances have been derived using the reduced proper-motion diagram for 2.1 × l05 stars of estimated blue absolute-magnitude range 2-9. The density gradient of the hotter stellar system (-0.56 dex kpc-1) suggests a spheroidlike stellar structure where as the density gradient of the cooler system (-1.37 dex kpc-1) suggests a disklike structure. A kinematically hotter and cooler two-component model for the repartition of stars of absolute magnitude 2-9 up to a distance of 500 pc from the Sun has been derived from a cross section of the galactic meridian (lII = 45°, and lII = 225°). A set of 103 stars with high planar orbital eccentricity is extracted from the hotter stellar system for further metallicity analysis and preliminary analysis of high dispersion spectra of 102 stars from this sample indicates ten potential F and G halo dwarfs, which implies a detection rate close to 10%. A long-term star-by-star observational program was produced from a biased kinematic sample of 103 stars discriminated by an adequate analysis of 106 stars, with the possibility of discovering about 102 true halo dwarfs.
No associations
LandOfFree
Kinematical classification of stars of blue apparent magnitude 9.5-12.5 and of annual proper motion 0.02-0.20 arcsec into two systems of low (20 km/s) and high (70 km/s) velocity dispersion in the galactic plane 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 Kinematical classification of stars of blue apparent magnitude 9.5-12.5 and of annual proper motion 0.02-0.20 arcsec into two systems of low (20 km/s) and high (70 km/s) velocity dispersion in the galactic plane, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Kinematical classification of stars of blue apparent magnitude 9.5-12.5 and of annual proper motion 0.02-0.20 arcsec into two systems of low (20 km/s) and high (70 km/s) velocity dispersion in the galactic plane will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1301614