Stellar Radial Velocities in the Perseus Arm.
Abstract
Published stellar radial velocities it tl e viciiiit of h and Persei (1" 1300), yield a meai that is algebraically larger by 7.4 l m$sec than the 21-cm velocities of the neutral hydrogen in the center of that arm. To investigate this discrepancy, velocities have been obtained for 45 stars in a more distant section of the Perseus Arm at lIT - 1000. Twenty- four of these stars seem to have constant radial velocities and their mean velocity agrees well with the 21-cm velocity for the center of the arm. However, the mean velocity from three observations of each of the 21 variable-velocity stars exceeds that from the constant-velocity stars by 15.6+3.7 (p.e.) km/sec. An explanation for this difference, involving the effect of gaseous streams on the observed stellar radial velocities, is proposed. If the velocities of the constant and variable-velocity stars are averaged together, the mean exceeds the 21-cm velocity for the center of the arm by 8.7 km/sec, which is similar to the result for the h and x Persei region. It is therefore suggested that the velocities of many OB-type spectroscopic binaries may be systematically too large and may be unreliable for galactic-structure studies.
- Publication:
-
The Astronomical Journal
- Pub Date:
- September 1963
- DOI:
- 10.1086/109086
- Bibcode:
- 1963AJ.....68R.271A