Open AccessThe mass of the neutron star in the binary millisecond pulsar PSR J 1012 + 5307
Author(s) -
Callanan Paul J.,
Garnavich Peter M.,
Koester Detlev
Publication year - 1998
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1998.01634.x
Subject(s) - physics , neutron star , astrophysics , millisecond pulsar , pulsar , white dwarf , astronomy , binary pulsar , x ray binary , solar mass , x ray pulsar , low mass , binary star , mass ratio , stars
We have measured the radial velocity variation of the white dwarf secondary in the binary system containing the millisecond pulsar PSR J 1012 + 5307. Combined with the orbital parameters of the radio pulsar, we infer a mass ratio q (≡ M 1 / M 2 ) = 10.5 ± 0.5. Our optical spectroscopy has also allowed us to determine the mass of the white dwarf companion by fitting the spectrum to a grid of DA model atmospheres: we estimate M 2 = 0.16 ± 0.02 M⊙, and hence the mass of the neutron star is 1.64 ± 0.22 M⊙, where the error is dominated by that of M 2 . The orbital inclination is 52 ± 4°. For an initial neutron star mass of ∼ 1.4 M⊙, only a few tenths of a solar mass at most has been successfully accreted over the lifetime of the progenitor low‐mass X‐ray binary. If the initial mass of the secondary was ∼ 1 M⊙, our result suggests that the mass transfer may have been non‐conservative.