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 , , 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 J2000      Equinox J2000
Constellation Corona Australis
Right ascension 18h 25m 46.8186s[1]
Declination −37° 06′ 18.529″[1]
Radial velocity (Rv)−91.0[2] km/s
Proper motion (μ) RA: −9.222[1] mas/yr
Dec.: −2.542[1] mas/yr
Parallax (π)0.1205 ± 0.0577[1] mas
Distanceapprox. 30,000 ly
(approx. 8,000 pc)
Neutron star
Mass1.14–2.32 M
Database references


  1. ^ a b c d e 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.
  2. ^ 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.
  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. S2CID 6917472.
  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. S2CID 54716062.
  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. S2CID 15389279.