Stellar Kinematics and Spiral Arms.

Abstract

view Abstract Citations (1) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Stellar Kinematics and Spiral Arms. Young, Andrew T. Abstract Monte Carlo calculations of the velocity distribution of young stars in the solar neighborhood have been made on the IBM 7090 computer of the Smithsonian Astrophysical Observatory, assuming that: (1) stars are formed only in spiral arms; (2) the velocity distribution of newly formed stars is isotropic and Gaussian in form, and its centroid coincides with the motion of the gas (which differs from the gravitational circular velocity); (3) the arm shares the physical motion of the gas. It is found that if the gas velocity is that recently found by Kerr (an outward streaming of about 7 km/sec relative to the standard solar motion), and if the tilt in the arms is small (as indicated by the 21-cm observations), then the observed velocity distribution for relatively young stars can be comple,tely accounted for. In particular, the vertex deviation and anomalous axial ratios of the velocity ellipsoid are quantitatively explained. Furthermore, the motion of the sun relative to the local circular velocity turns out to lie much closer to Vyssotsky's "basic solar motion" than to the "standard solar motion" of 20 km/sec. Publication: The Astronomical Journal Pub Date: September 1961 DOI: 10.1086/108430 Bibcode: 1961AJ.....66..299Y full text sources ADS |