T Coronae Borealis

T Coronae Borealis (T CrB), is a recurring nova in the constellation Corona Borealis. It was first discovered in outburst in 1866 by John Birmingham,[11] although it had been observed earlier as a 10th magnitude star.[12]

T Coronae Borealis
Location of T Coronae Borealis (circled in red)
Observation data
Epoch J2000      Equinox J2000
Constellation Corona Borealis
Right ascension 15h 59m 30.1622s[1]
Declination 25° 55′ 12.613″[1]
Apparent magnitude (V) 2.0–10.8[2]
Characteristics
Evolutionary stage Red giant + white dwarf
Spectral type M3III+p[3]
Variable type recurrent nova[2]
Astrometry
Radial velocity (Rv)−27.79[4] km/s
Proper motion (μ) RA: −4.220[5] mas/yr
Dec.: 12.364[5] mas/yr
Parallax (π)1.2127 ± 0.0488[5] mas
Distance806+34
−30[6] pc
Orbit
Period (P)227.8 d[7]
Semi-major axis (a)0.54 AU[6]
Eccentricity (e)0.0[7]
Inclination (i)67[8]°
Details
Red giant
Mass1.12[6] M☉
Radius75[8] R☉
Luminosity655[9] L☉
Surface gravity (log g)2.0[10] cgs
Temperature3,600[10] K
White dwarf
Mass1.37[6] M☉
Luminosity~100[8] L☉
Other designations
BD+26° 2765, HD 143454, HIP 78322, SAO 84129, 2MASS J15593015+2555126
Database references
SIMBADdata

Description
The light curve of T Coronae Borealis during the time surrounding its 1946 eruption, plotted from AAVSO data

T CrB normally has a magnitude of about 10, which is near the limit of typical binoculars. It has been seen to outburst twice, reaching magnitude 2.0 on May 12, 1866 and magnitude 3.0 on February 9, 1946,[13] although a more recent paper shows the 1866 outburst with a possible peak range of magnitude 2.5 ± 0.5.[14] Even when at peak magnitude of 2.5, this recurrent nova is dimmer than about 120 stars in the night sky.[15] It is sometimes nicknamed the Blaze Star.[16]

T CrB is a binary system containing a large cool component and a smaller hot component. The cool component is a red giant which is transferring material to the hot component. The hot component is a white dwarf surrounded by an accretion disc, all hidden inside a dense cloud of material from the red giant. When the system is quiescent, the red giant dominates the visible light output and the system appears as an M3 giant. The hot component contributes some emission and dominates the ultraviolet output. During outbursts, the transfer of material to the hot component increases greatly, the hot component expands, and the luminosity of the system increases.[6][8][17] [18]

AAVSO light curve of recurrent nova T CrB from 1 Jan 2008 to 17 Nov 2010, showing the pulsations of the red giant primary. Up is brighter and down is fainter. Day numbers are Julian day.

The two components of the system orbit each other every 228 days. The orbit is almost circular and is inclined at an angle of 67°. The stars arec separated by 0.54 AU.[6]

2016-present activity

On 20 April 2016, the Sky and Telescope newsletter reported a recent sustained brightening since February 2015 from magnitude 10.5 to about 9.2. A similar event was reported in 1938, shortly before the 1946 outburst.[19] As of June 2018, the star has dimmed slightly but still remains at an unusually high level of activity.

References
  1. Gaia Collaboration; et al. (November 2016). "Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties". Astronomy & Astrophysics. 595: 23. arXiv:1609.04172. Bibcode:2016A&A...595A...2G. doi:10.1051/0004-6361/201629512. S2CID 1828208. A2.
  2. 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.
  3. Shenavrin, V. I.; Taranova, O. G.; Nadzhip, A. E. (2011). "Search for and study of hot circumstellar dust envelopes". Astronomy Reports. 55 (1): 31–81. Bibcode:2011ARep...55...31S. doi:10.1134/S1063772911010070. S2CID 122700080.
  4. Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; Levato, H.; Morrell, N. I.; Torres, G.; Udry, S. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727–732. arXiv:astro-ph/0406573. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. S2CID 119387088.
  5. 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.
  6. Linford, Justin D.; Chomiuk, Laura; Sokoloski, Jennifer L.; Weston, Jennifer H. S.; Van Der Horst, Alexander J.; Mukai, Koji; Barrett, Paul; Mioduszewski, Amy J.; Rupen, Michael (2019). "T CRB: Radio Observations during the 2016-2017 "Super-active" State". The Astrophysical Journal. 884 (1): 8. arXiv:1909.13858. Bibcode:2019ApJ...884....8L. doi:10.3847/1538-4357/ab3c62. S2CID 203593955.
  7. Fekel, Francis C.; Joyce, Richard R.; Hinkle, Kenneth H.; Skrutskie, Michael F. (2000). "Infrared Spectroscopy of Symbiotic Stars. I. Orbits for Well-Known S-Type Systems". The Astronomical Journal. 119 (3): 1375. Bibcode:2000AJ....119.1375F. doi:10.1086/301260.
  8. Stanishev, V.; Zamanov, R.; Tomov, N.; Marziani, P. (2004). "Hα variability of the recurrent nova T Coronae Borealis". Astronomy and Astrophysics. 415 (2): 609–616. arXiv:astro-ph/0311309. Bibcode:2004A&A...415..609S. doi:10.1051/0004-6361:20034623. S2CID 3000175.
  9. Schaefer, Bradley E. (2009). "Orbital Periods for Three Recurrent Novae". The Astrophysical Journal. 697 (1): 721–729. arXiv:0903.1349. Bibcode:2009ApJ...697..721S. doi:10.1088/0004-637X/697/1/721. S2CID 16087253.
  10. Wallerstein, George; Harrison, Tanya; Munari, Ulisse; Vanture, Andrew (2008). "The Metallicity and Lithium Abundances of the Recurring Novae T CrB and RS Oph". Publications of the Astronomical Society of the Pacific. 120 (867): 492. Bibcode:2008PASP..120..492W. doi:10.1086/587965.
  11. Pettit, Edison (1946). "The Light-Curves of T Coronae Borealis". Publications of the Astronomical Society of the Pacific. 58 (341): 153. Bibcode:1946PASP...58..153P. doi:10.1086/125797.
  12. Barnard, E. E. (1907). "Nova T Coronae of 1866". Astrophysical Journal. 25: 279. Bibcode:1907ApJ....25..279B. doi:10.1086/141446.
  13. Sanford, Roscoe F. (1949). "High-Dispersion Spectrograms of T Coronae Borealis". Astrophysical Journal. 109: 81. Bibcode:1949ApJ...109...81S. doi:10.1086/145106.
  14. Schaefer, Bradley E. (2010). "Comprehensive Photometric Histories of All Known Galactic Recurrent Novae". The Astrophysical Journal Supplement Series. 187 (2): 275–373. arXiv:0912.4426. Bibcode:2010ApJS..187..275S. doi:10.1088/0067-0049/187/2/275. S2CID 119294221.
  15. "Vmag<2.5". SIMBAD Astronomical Database. Retrieved 2010-06-25.
  16. A Digital Spectral Classification Atlas, R. O. Gray, 34. Unusual Stellar Spectra III: two emission-line stars
  17. Iłkiewicz, Krystian; Mikołajewska, Joanna; Stoyanov, Kiril; Manousakis, Antonios; Miszalski, Brent (2016). "Active phases and flickering of a symbiotic recurrent nova T CrB". Monthly Notices of the Royal Astronomical Society. 462 (3): 2695. arXiv:1607.06804. Bibcode:2016MNRAS.462.2695I. doi:10.1093/mnras/stw1837. S2CID 119104759.
  18. Luna, GJM; Mukai, K.; Sokoloski, J. L.; Nelson, T.; Kuin, P.; Segreto, A.; Cusumano, G.; Jaque Arancibia, M.; Nuñez, N. E. (2018). "Dramatic change in the boundary layer in the symbiotic recurrent nova T Coronae Borealis". Astronomy and Astrophysics. 619 (1): 61. arXiv:1807.01304. Bibcode:2018A&A...619A..61L. doi:10.1051/0004-6361/201833747. S2CID 119078482.
  19. "Is T CrB About to Blow its Top?". Sky and Telescope newsletter. Retrieved 2017-08-06.

Further reading
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