Spatial distribution and kinematics of OB stars
Abstract
The sample of 37 485 suspected OB stars selected by Gontcharov (2008) from the Tycho2 catalogue has been cleaned of the stars that are not of spectral types OVA0V. For this purpose, the apparent magnitude V _{ T } from Tycho2, the absolute magnitude M_{V_T } calibrated as a function of the dereddened color index ( B _{ T }  V _{ T })_{0}, the interstellar extinction A_{V_T } calculated from the 3D analytical model by Gontcharov (2009) as a function of the Galactic coordinates, and the photometric distance r _{ph} calculated as a function of V _{ T }, M_{V_T }, and A_{V_T } have been reconciled in an iterative process. The 20 514 stars that passed the iterations have ( B _{ T }  V _{ T })_{0} < 0 and M_{V_T } > 5 and are considered as a sample of OVA0V stars complete within 350 pc of the Sun. Based on the theoretical relation between the dereddened color and age of the stars, the derived sample has been divided into three subsamples: ( B _{ T }  V _{ T })_{0} < 0.2, 0.2 < ( B _{ T }  V _{ T })_{0} < 0.1, and 0.1 < ( B _{ T }  V _{ T })_{0} < 0, younger than 100, 100200, and 200400 Myr, respectively. The spatial distribution of all 20 514 stars and the kinematics analyzed for more than 1500 stars with radial velocities from the PCRV and RAVE catalogues are different for the subsamples, showing smooth rotations, shears, and deformations of the layer of gas producing stars with the formation of the Gould Belt, the Great Tunnel, the Local Bubble, and other structures within the last 200 Myr. The detected temporal variations of the velocity dispersions, solar motion components, OgorodnikovMilne model parameters, and Oort constants are significant, agree with the results of other authors, and show that it is meaningless to calculate the kinematic parameters for samples of stars with uncertain ages or with a wide range of ages.
 Publication:

Astronomy Letters
 Pub Date:
 November 2012
 DOI:
 10.1134/S1063773712110035
 arXiv:
 arXiv:1606.09028
 Bibcode:
 2012AstL...38..694G
 Keywords:

 star counts;
 distribution of stars;
 HertzsprungRussell diagram;
 main sequence;
 early types (O and B);
 stellar kinematics;
 Galactic solar neighborhood;
 Astrophysics  Solar and Stellar Astrophysics;
 Astrophysics  Astrophysics of Galaxies
 EPrint:
 7 figures, 1 table