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The Symbiotic Neutron Star Binary GX 1+4/V2116 Ophiuchi

1997; IOP Publishing; Volume: 489; Issue: 1 Linguagem: Inglês

10.1086/304779

1538-4357

Deepto Chakrabarty, P. Roche,

Pulsars and Gravitational Waves Research

We present extensive optical, infrared, and X-ray observations of the S-type symbiotic low-mass X-ray binary GX 1+4/V2116 Oph, which consists of a 2 minute X-ray pulsar accreting from an M6 III giant. This is the only symbiotic system definitely known to contain a neutron star. The mean observed spectral type of the X-ray-heated mass donor is M5 III. The steady interstellar extinction toward the binary (AV = 5.0 ± 0.6) contrasts the variable hydrogen column density inferred from X-ray measurements, most likely evidence for a variable stellar wind. The mass donor is probably near the tip of the first-ascent red giant branch, in which case the system is 3-6 kpc distant and has an X-ray luminosity of ~1037 ergs s-1. It is also possible, though less likely, that the donor star is just beginning its ascent of the asymptotic giant branch, in which case the system is 12-15 kpc distant and has an X-ray luminosity of ~1038 ergs s-1. However, our measured AV argues against such a large distance.