V691 Coronae Australis

X1822–371, associated with the optically visible star V691 Coronae Australis (abbreviated V691 CrA), is a neutron-star X-ray binary system at a distance of approximately 2-2.5 kiloparsecs[3]. It is known to have a high inclination of i = 82.5°± 1.5°[4]. This source displays relatively high brightness in the optical wavelengths when compared to the X-ray, making it a prototypical Accretion Disk Coronae (ADC) source, i.e. a source with a corona extending above and below its accretion disk. The only-partial eclipses in its light curve, even at such a high inclination, support this hypothesis. Estimates of the mass of its neutron star lies between 1.14–2.32 solar masses. The optical spectrum of X1822–371 displays strong Hα, Hβ, He I, He II and Bowen Blend features. These features have been extensively studied using the technique of Doppler tomography.[5][6][7]

V691 Coronae Australis
Observation data
Epoch       Equinox
Constellation Corona Australis
Right ascension  18h 25m 46.81s
Declination −37° 06′ 18.52″
Astrometry
Radial velocity (Rv)-91.0[1] km/s
Proper motion (μ) RA: -9.222[2] mas/yr
Dec.: -2.542[2] mas/yr
Parallax (π)0.1205 ± 0.0577[2] mas
Distanceapprox. 30,000 ly
(approx. 8,000 pc)
Details
Neutron star
Mass1.14–2.32 M☉
Database references
SIMBADdata

References
  1. Duflot, M.; Figon, P.; Meyssonnier, N. (1995). "Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue". Astronomy and Astrophysics Supplement Series. 114: 269. Bibcode:1995A&AS..114..269D.
  2. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  3. Mason, K. O.; Cordova, F. A. (November 1982). "Infrared photometry of the X-ray binary 2A 1822-371 - A model for the ultraviolet, optical, and infrared light curve". The Astrophysical Journal. 262: 253. Bibcode:1982ApJ...262..253M. doi:10.1086/160416. ISSN 0004-637X.
  4. Heinz, S.; Nowak, M. A. (2001-01-11). "The Flared Disc Project: RXTE and ASCA observations of X 1822--371". Monthly Notices of the Royal Astronomical Society. 320 (2): 249–260. arXiv:astro-ph/0008053. Bibcode:2001MNRAS.320..249H. doi:10.1046/j.1365-8711.2001.03946.x. ISSN 0035-8711.
  5. Peris, C. S.; Vrtilek, S. D. (2012-12-01). "A tomographic study of V691 CrA (X1822−371): A tomographic study of V691 CrA (X1822−371)". Monthly Notices of the Royal Astronomical Society. 427 (2): 1043–1051. doi:10.1111/j.1365-2966.2012.22039.x.
  6. Somero, A.; Hakala, P.; Muhli, P.; Charles, P.; Vilhu, O. (March 2012). "Phase-resolved optical and X-ray spectroscopy of low-mass X-ray binary X1822-371". A&A. 539: A111. arXiv:1201.3461. Bibcode:2012A&A...539A.111S. doi:10.1051/0004-6361/201118439. ISSN 0004-6361.
  7. Casares, J.; Steeghs, D.; Hynes, R. I.; Charles, P. A.; O’Brien, K. (2003-06-20). "Bowen Fluorescence from the Companion Star in X1822−371". The Astrophysical Journal. 590 (2): 1041–1048. arXiv:astro-ph/0303263. Bibcode:2003ApJ...590.1041C. doi:10.1086/375055. ISSN 0004-637X.
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