The donor of Aquila X-1 revealed by high-angular resolution near-infrared spectroscopy

The low-mass X-ray binary Aquila X-1 is one of the most active neutron star X-ray transients. Despite its relatively bright quiescent optical counterpart, the detection of its companion has been hampered by the presence of a nearby interloper star. Using the Spectrograph for INtegral Field Observati...

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Bibliographic Details
Published in:Monthly notices of the Royal Astronomical Society. Letters 2017-01, Vol.464 (1), p.L41-L45
Main Authors: Mata Sánchez, D., Muñoz-Darias, T., Casares, J., Jiménez-Ibarra, F.
Format: Article
Language:English
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Summary:The low-mass X-ray binary Aquila X-1 is one of the most active neutron star X-ray transients. Despite its relatively bright quiescent optical counterpart, the detection of its companion has been hampered by the presence of a nearby interloper star. Using the Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI) on the Very Large Telescope-8.2m telescope, we unambiguously single out Aquila X-1 from the interloper. Phase-resolved near-infrared spectroscopy reveals absorption features from a K4 ± 2 companion star moving at a projected velocity of K2 = 136 ± 4 km s− 1. We here present the first dynamical solution and associated fundamental parameters of Aquila X-1, imposing new constraints on the orbital inclination (36° < i < 47°) and the distance (d = 6 ± 2 kpc) to this prototypical neutron star transient.
ISSN:1745-3925
1745-3933
DOI:10.1093/mnrasl/slw172