Pulsar velocity observations: Correlations, interpretations, and discussion

Journal Article · Thu Sep 15 00:00:00 EDT 1977 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/155529· OSTI ID:7297924

Helfand, D J; Tademaru, E

From an examination of the current sample of 12 pulsars with measured proper motions and the z-distribution of the much larger group of over 80 sources with measured period derivatives, we develop a self-consistent picture of pulsar evolution. The apparent tendency of pulsars to move parallel to the galactic plane is explained as the result of various selection effects. A method for calculating the unmeasurable radial velocity of a pulsar is presented; it is shown that the total space velocities thus obtained are consistent with the assumption of an extreme Population I origin for pulsars which subsequently move away from the plane with a large range of velocities. The time scale for pulsar magnetic field decay is derived from dynamical considerations. A strong correlation of the original pulsar field strength with the magnitude of pulsar velocity is discussed. This results in the division of pulsars into two classes: Class A sources characterized by low space velocities, a small scale height, and low values of P/sub 0/P/sub 0/; and Class B sources with a large range of velocities (up to 1000 km s/sup -1/), a much greater scale height, and larger values of initial field strength. It is postulated that Class A sources originate in tight binaries where their impulse acceleration at birth is insufficient to remove them from the system, while the Class B sources arise from single stars or loosely bound binaries and are accelerated to high velocities by their asymmetric radiation force. The evolutionary picture which is developed is shown to be consistent with a number of constraints imposed by supernova rates, the relative frequency of massive binaries and Class A sources, theoretical field-decay times, and the overall pulsar galactic distribution.

• Research Organization: Department of Physics and Astronomy, University of Massachusetts
• OSTI ID: 7297924
• Journal Information: Astrophys. J.; (United States), Vol. 216:3
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
PULSARS
PROPER MOTION
STAR EVOLUTION
BINARY STARS
MAGNETIC FIELDS
RADIAL VELOCITY
SPATIAL DISTRIBUTION
COSMIC RADIO SOURCES
DISTRIBUTION
MOTION
STARS
VELOCITY
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources