Stellar Population Properties Research Articles

The Stellar Kinematics in the Main Meridional Section of the Galaxy

In the framework of the programme of studying the meridional section of the Galaxy (MEGA) the catalogue of stellar data (about 26500 stars) had been compiled and investigated. The main part of the catalogue consist of the proper motions of stars with respect to the galaxies. The stellar kinematical characteristics in the direction of the galactic rotation, the parameters of velocity ellipsoid and the relation between kinematical, spatial and chemical properties of stellar populations have been determined.

Kinematic modeling of the Galaxy. I - The Yale Bright Star Catalogue

A code has been developed to investigate the kinematic properties of stellar populations of the Galaxy by modeling the distributions of proper motion and line-of-sight velocity. The coordinate frames of reference are discussed in detail and the general matrix transformations valid beyond the solar neighborhood are given. As a first application, the kinematic properties of the magnitude-selected sample of 3993 stars in the Bright Star Catalogue with V less than 6.0 and (B-V) greater than 0 are selected. The observed kinematic distributions are compared with a conventional model that has an exponential disk with scale heights, components of velocity dispersion ellipsoid, and asymmetric drift taken from the literature and defined as functions of spectral type. The comparisons suggest that a significant fraction of the Bright Star Catalogue belongs to a relatively young population that is not properly represented in the model.

Kinematics of the Galactic Inner Spheroid

Analysis of the detailed photometric, kinematic and chemical properties of stellar populations constrains the formation history of the Galaxy. We have completed a photometric survey and initiated a spectroscopic survey, obtaining radial velocities and abundances for volume complete samples of spheroid dwarfs in situ, to distances of a few kpc. Three fields under study are those for which Chiu (Ap. J. Suppl. 1980) obtained proper motions - SA 57 (NGP), SA51 (anticenter field) and SA68. Two of these fields are on the sun - Galactic center meridional plane (SA57 and SA51) so that (U,V) and (V,W) components of space motion respectively may be derived on the basis of the proper motions alone, once distances have been obtained. Our initial distance estimates are from Chiu's photometry and population classes, which are based on the position of the star on the reduced proper motion diagram.

Multiaperture photometry of isolated galaxies

view Abstract Citations (14) References (37) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Multiaperture photometry of isolated galaxies. Brosch, N. ; Shaviv, G. Abstract Multiaperture U, B, V photometry of isolated galaxies by Huchra and Thuan (1977) is used in an investigation of changes in the stellar population and other properties in galaxies found in low density regions. The photometry shows a behavior different from normal field galaxies in that the inner regions of the isolated galaxies appear to have excess blueness similar to galaxies with active nuclei. Results indicate that gas which does not escape from isolated galaxies sinks into the nucleus and gives rise to nonstellar radiation, which may be a major contribution to the radiation in the deep nuclei of the HT galaxies. Publication: The Astrophysical Journal Pub Date: February 1982 DOI: 10.1086/159655 Bibcode: 1982ApJ...253..526B Keywords: Astronomical Photometry; Galactic Radiation; Galactic Structure; Star Distribution; Ubv Spectra; Apertures; Astrometry; Galactic Nuclei; Mass Distribution; Astronomy full text sources ADS | data products NED (12)