title: Binary Pulsar PSR 1913 + 16: Model for Its Origin.
abstract: The existing observational data for the binary pulsar PSR 1913 + 16 are sufficient to give a rather well-defined model for the system. On the basis of evolutionary considerations, the pulsar must be a neutron star near the upper mass limit of 1.2 solar masses (M.). The orbital inclination is probably high, i>/= 700, and the mass of the unseen companion probably lies close to the upper limit of the range 0.25 M. to 1.0 M.. The secondary cannot be a main sequence star and is probably a degenerate helium dwarf. At the 5.6-kiloparsec distance indicated by the dispersion measure, the magnetic dipole model gives an age of approximately 4 x 104 years, a rate of change of the pulsar period of P approximately 2 nanoseconds per day, and a surface magnetic field strength approximately (1/3) that of the Crab pulsar. The pulsar is fainter than an apparent magnitude V approximately + 26.5 and is at least approximately 80 times fainter than the Crab pulsar in the x-ray band. The companion star should be fainter than V approximately + 30, and a radio supernova remnant may be detectable near the position of the pulsar at a flux level of </=10 janskys. Important tests of this model will be provided by more accurate measurement of P and by a careful search for a faint supernova remnant.
authors.forename: H M
authors.initials: HM
authors.lastname: Van Horn
authors.forename: S
authors.initials: S
authors.lastname: Sofia
authors.forename: M P
authors.initials: MP
authors.lastname: Savedoff
authors.forename: J G
authors.initials: JG
authors.lastname: Duthie
authors.forename: R A
authors.initials: RA
authors.lastname: Berg