V404 Cygni

V404 Cygni

X-ray light echoes from the 2015 nova eruption
Credit: Andrew Beardmore (Univ. of Leicester) and NASA/Swift
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cygnus
Right ascension 20h 24m 03.82s[1]
Declination +33° 52′ 02.0″[1]
Apparent magnitude (V) 11.2 - 18.8[2]
Characteristics
Spectral type K3 III[3]
U−B color index +0.3[4]
B−V color index +1.5[4]
Variable type Nova[5]
Astrometry
Proper motion (μ) RA: −5.177[1] mas/yr
Dec.: −7.778[1] mas/yr
Parallax (π)0.3024 ± 0.0783 mas[1]
Distance2,390[6] pc
Absolute magnitude (MV)+3.4[7]
Details
A (black hole)
Mass9[6] M☉
B
Mass0.7[7] M☉
Radius6.0[7] R☉
Luminosity10.2[7] L☉
Surface gravity (log g)3.50[8] cgs
Temperature4,800[8] K
Metallicity [Fe/H]+0.23[8] dex
Rotational velocity (v sin i)36.4[8] km/s
C
Mass1.2[9] M☉
Radius1.85[9] R☉
Surface gravity (log g)3.95[9] cgs
Temperature6123[9] K
Metallicity [Fe/H]-0.09[9] dex
Age4 Gyr
Other designations
V404 Cyg, Nova Cygni 1938, Nova Cygni 1989, GS 2023+338, AAVSO 2020+33
Database references
SIMBADdata

V404 Cygni is a microquasar and a triple star system in the constellation of Cygnus. It contains a black hole with a mass of about 9 M☉ and an early K giant star companion with a mass slightly smaller than the Sun, and an evolved tertiary component. The inner star and the black hole orbit each other every 6.47129 days at fairly close range, while the outer tertiary takes 70000 years to orbit the inner binary system.[10] Due to their proximity and the intense gravity of the black hole, the secondary star loses mass to an accretion disk around the black hole and ultimately to the black hole itself.[11]

The "V" in the name indicates that it is a variable star, which repeatedly gets brighter and fainter over time. It is also considered a nova, because at least three times in the 20th century it produced a bright outburst of energy. Finally, it is a soft X-ray transient because it periodically emits short bursts of X-rays.

The black hole companion has been proposed as a Q star candidate.[12]

  1. ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. ^ Watson, C. L. (2006). "The International Variable Star Index (VSX)". The Society for Astronomical Sciences 25th Annual Symposium on Telescope Science. Held May 23–25. 25: 47. Bibcode:2006SASS...25...47W.
  3. ^ Khargharia, Juthika; Froning, Cynthia S.; Robinson, Edward L. (2010). "Near-infrared Spectroscopy of Low-mass X-ray Binaries: Accretion Disk Contamination and Compact Object Mass Determination in V404 Cyg and Cen X-4". The Astrophysical Journal. 716 (2): 1105. arXiv:1004.5358. Bibcode:2010ApJ...716.1105K. doi:10.1088/0004-637X/716/2/1105. S2CID 119116307.
  4. ^ a b Liu, Q. Z.; Van Paradijs, J.; Van Den Heuvel, E. P. J. (2007). "A catalogue of low-mass X-ray binaries in the Galaxy, LMC, and SMC (Fourth edition)". Astronomy and Astrophysics. 469 (2): 807. arXiv:0707.0544. Bibcode:2007A&A...469..807L. doi:10.1051/0004-6361:20077303. S2CID 14673570.
  5. ^ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  6. ^ a b Bernardini, F.; Russell, D. M.; Shaw, A. W.; Lewis, F.; Charles, P. A.; Koljonen, K. I. I.; Lasota, J. P.; Casares, J. (2016). "Events leading up to the 2015 June Outburst of V404 Cyg". The Astrophysical Journal Letters. 818 (1): L5. arXiv:1601.04550. Bibcode:2016ApJ...818L...5B. doi:10.3847/2041-8205/818/1/L5. S2CID 119251825.
  7. ^ a b c d Shahbaz, T.; Ringwald, F. A.; Bunn, J. C.; Naylor, T.; Charles, P. A.; Casares, J. (1994). "The mass of the black hole in V404 Cygni". Monthly Notices of the Royal Astronomical Society. 271: L10–L14. Bibcode:1994MNRAS.271L..10S. doi:10.1093/mnras/271.1.L10.
  8. ^ a b c d González Hernández, Jonay I.; Casares, Jorge; Rebolo, Rafael; Israelian, Garik; Filippenko, Alexei V.; Chornock, Ryan (2011). "Chemical Abundances of the Secondary Star in the Black Hole X-Ray Binary V404 Cygni". The Astrophysical Journal. 738 (1): 95. arXiv:1106.4278. Bibcode:2011ApJ...738...95G. doi:10.1088/0004-637X/738/1/95. S2CID 118443418.
  9. ^ a b c d e Burdge, Kevin B.; El-Badry, Kareem; Kara, Erin; Canizares, Claude; Chakrabarty, Deepto; Frebel, Anna; Millholland, Sarah C.; Rappaport, Saul; Simcoe, Rob; Vanderburg, Andrew (2024). "The black hole low mass X-ray binary V404 Cygni is part of a wide hierarchical triple, and formed without a kick". arXiv:2404.03719 [astro-ph.HE].
  10. ^ Burdge, Kevin B.; El-Badry, Kareem; Kara, Erin; Canizares, Claude; Chakrabarty, Deepto; Frebel, Anna; Millholland, Sarah C.; Rappaport, Saul; Simcoe, Rob; Vanderburg, Andrew (2024-10-23). "The black hole low-mass X-ray binary V404 Cygni is part of a wide triple". Nature: 1–5. doi:10.1038/s41586-024-08120-6. ISSN 1476-4687.
  11. ^ Kimura, Mariko; et al. (7 January 2016). "Repetitive patterns in rapid optical variations in the nearby black-hole binary V404 Cygni". Nature. 529 (7584): 54–70. arXiv:1607.06195. Bibcode:2016Natur.529...54K. doi:10.1038/nature16452. PMID 26738590. S2CID 4463697.
  12. ^ Brecher, K. (1993-05-01). "Gray Holes". American Astronomical Society Meeting Abstracts #182. 182: 55.07. Bibcode:1993AAS...182.5507B.