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The masses of the millisecond pulsar J1012+5307 and its white-dwarf companion | M. H. van Kerkwijk
; P. Bergeron
; S. R. Kulkarni
; | Date: |
7 Jun 1996 | Journal: | Astrophys. J. 467, L89 (1996) | Subject: | astro-ph | Affiliation: | Palomar Observatory, Caltech), P. Bergeron (Universite de Montreal), S. R. Kulkarni (Palomar Observatory, Caltech | Abstract: | We report on spectroscopy of the white-dwarf companion of the millisecond radio pulsar PSR J1012+5307. We find strong Balmer absorption lines, as would be expected for a cool DA white dwarf. The profiles are much narrower than usual, however, and lines are seen up to H12, indicating that the companion has a low gravity and hence a low mass. This is consistent with the expectation---based on evolutionary considerations and on the mass function---that it is a low-mass white dwarf with a helium core. By comparing the spectra to model atmospheres, we derive an effective temperature $T_{
m{}eff}=8550pm25,$K and a surface gravity $log{}g=6.75pm0.07$ (cgs units). Using the Hamada-Salpeter mass-radius relation for helium white dwarfs, with an approximate correction for finite-temperature effects, we infer a mass $mwd=0.16pm0.02,msun$. This is the lowest mass among all spectroscopically identified white dwarfs. We determine radial velocities from our spectra, and find a radial-velocity amplitude of $280pm15,kms$. With the pulsar’s radial-velocity amplitude, the mass ratio $mpsr/mwd=13.3pm0.7$. From all constraints, we find that with 95confidence $1.5 | Source: | arXiv, astro-ph/9606045 | Services: | Forum | Review | PDF | Favorites |
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