The mass of the neutron star in the binary millisecond pulsar PSR J 1012 + 5307 |
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Authors: | Paul J. Callanan,Peter M. Garnavich,& Detlev Koester |
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Affiliation: | Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA,;Institut für Astronomie und Astrophysik der Universität Kiel, D-24098, Kiel, Germany |
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Abstract: | 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. |
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Keywords: | stars: binaries: general neutron pulsars: individual: PSR J 1012 ± 5307 |
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