Astronomy:T Coronae Borealis

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Short description: Recurrent nova in the constellation Corona Borealis
Not to be confused with Tau Coronae Borealis.
"Blaze Star" redirects here. It is not to be confused with Blaze Starr.

T Coronae Borealis
star map centered on Corona Borealis
Location of T Coronae Borealis (circled in red)
Observation data
Equinox J2000.0]] (ICRS)
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[3]
Spectral type M3III+p[4]
Variable type recurrent nova[2]
Astrometry
Radial velocity (Rv)−27.75±0.04[5] km/s
Proper motion (μ) RA: −4.461[1] mas/yr
Dec.: 12.016[1] mas/yr
Parallax (π)1.0920 ± 0.0275[1] mas
Distance2,990 ± 80 ly
(920 ± 20 pc)
Absolute magnitude (MV)+0.16 (min.)[6]
Orbit[5]
Period (P)227.5528±0.0002 days
Semi-major axis (a)0.960 AU
Eccentricity (e)0.009±0.003[7]
Inclination (i)61.5°
Periastron epoch (T)2459978.37±0.08
Semi-amplitude (K1)
(primary)		23.90±0.05 km/s
Details
Red giant
Mass0.93[5] M☉
Radius63.5±0.3[8] – 71.1[5] R☉
Luminosity583±4[8] L☉
Surface gravity (log g)0.672+0.009
−0.007[8] cgs
Temperature3,561±3[8] K
Metallicity [Fe/H]+0.20+0.05
−0.03[8] dex
Rotational velocity (v sin i)4.75±0.26[5] km/s
White dwarf
Mass1.35[5] M☉
Radius0.0045[9] R☉
Luminosity~100[10] L☉
Other designations
Blaze Star, T CrB, BD+26°2765, HD 143454, HIP 78322, HR 5958, SAO 84129, 2MASS J15593015+2555126[11]
Database references
SIMBADdata

T Coronae Borealis is a binary star and a recurrent nova about 3,000 light-years (920 parsecs) away in the constellation Corona Borealis.[12] It has the official proper name Blaze Star, T Coronae Borealis is the variable-star designation. The system was first observed in outburst in 1866 by John Birmingham,[13] though it had been observed earlier in quiescence as a 10th magnitude star.[14] It may have been observed in 1217 and in 1787 as well.[15][16] In February 1946, Michael Woodman, a 15-year-old schoolboy from Wales, observed a flare‐up, subsequently writing to the Astronomer Royal and leading to the theory that the star flares every 80 years,[17] with the next nova expected to occur before 2027.

Nomenclature

T Coronae Borealis (abbreviated T CrB or unofficially T Cor Bor)[18] is the star's variable star designation. It also has the Bright Star Catalogue designation HR 5958 and the Henry Draper Catalogue designation HD 143454.[11]

The proper name Blaze Star[19] has been used since its outburst in 1866, and was officially approved by the IAU Working Group on Star Names on 22 September 2025.[20]

Description

dot graph
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. Two well-documented outbursts have been observed, reaching magnitude 2.0 on May 12, 1866 and magnitude 3.0 on February 9, 1946,[21] though a more recent paper shows the 1866 outburst with a possible peak range of magnitude 2.5±0.5.[22] Even when at peak magnitude of 2.5, this recurrent nova is dimmer than about 100 brightest stars in the night sky,[23] but easily visible to the naked eye.

diagram of a red giant star and smaller companion star which is accreting gas from its companion
Diagram of T Coronae Borealis based on a description given by Kraft[3] using the updated mass ratio given by Stanishev[10]

T CrB is a binary system containing a large cool component and a smaller hot component. The cool component is a red giant that transfers material to the hot component.[3] 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 by orders of magnitude.[10][24][25][26]

dot graph
AAVSO light curve of recurrent nova T CrB from Jan 1, 2008 to Nov 17, 2010, showing rotating ellipsoidal variability. Up is brighter and down is fainter. Day numbers are Julian day.

The two components of the system orbit each other every 227.5528 d. The orbit is almost circular and is inclined at an angle of 61.5°. The radius of the orbit of the primary component around the center of mass is 0.960 astronomical unit|AU.[5]

2016–present activity

On April 20, 2016, Sky & Telescope reported a sustained brightening since February 2015 from magnitude 10.5 to about 9.2. A similar event was reported in 1938, followed by another outburst in 1946.[27] By June 2018, the star had dimmed slightly but still remained at an unusually high level of activity. By mid-2023, it had faded by 0.35 magnitude or about 28%;[lower-alpha 1] its lowest brightness seen since 2016.[28] A similar dimming occurred in the year before the 1946 outburst,[29] leading some to predict an eruption before September 2024.[30] As of March 2026, such a nova has not yet been observed, although some have predicted it is imminent.[29]

Outburst predictions

Predictions of the next nova (in order of when the prediction was made):

  • 2026-2027 (made in 1946 either by N. F. H. Knight or W. M. Lindley)[31]
  • Mid‐February 2024 to end‐September 2026 (made in March 2023)[32]
  • Beginning January 2024 to mid-August 2024 (made in June 2023)[33] (lapsed)
  • January 2024 (made in August 2023)[34] (lapsed)
  • End of October 2024 (made in June 2024)[35] (lapsed)
  • Around March 27, 2025 (lapsed); November 10, 2025 (lapsed); June 25, 2026; or February 8, 2027 (made in October 2024)[36]

Notes

  1. ↑ 1-100-0.35/5 = 0.2756

References

  1. ↑ 1.0 1.1 1.2 1.3 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 Samus, N. N. 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. ↑ 3.0 3.1 3.2 Kraft, Robert P. (1958). "The Binary System Nova T Coronae Borealis.". Astrophysical Journal (University of Chicago Press) 127: 625. doi:10.1086/146495. ISSN 0004-637X. Bibcode: 1958ApJ...127..625K. 
  4. ↑ Shenavrin, V. I.; Taranova, O. G.; Nadzhip, A. E. (2011). "Search for and study of hot circumstellar dust envelopes". Astronomy Reports (MAIK Nauka/Interperiodica) 55 (1): 31–81. doi:10.1134/S1063772911010070. CODEN ATROES. ISSN 1063-7729. OCLC 43712703. Bibcode: 2011ARep...55...31S. 
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 Munari, U.; Walter, F.; Masetti, N.; Valisa, P.; Dallaporta, S.; Bergamini, A.; Cherini, G.; Frigo, A. et al. (2025-07-31). "T CrB: overview of the accretion history, Roche-lobe filling, orbital solution, and radiative modeling". Astronomy and Astrophysics 701: A176. doi:10.1051/0004-6361/202555917. Bibcode: 2025A&A...701A.176M. 
  6. ↑ Nikolov, Yanko (2022). "Interstellar polarization and extinction toward the Recurrent Nova T CRB". New Astronomy (Elsevier) 97. doi:10.1016/j.newast.2022.101859. ISSN 1384-1092. OCLC 123402017. Bibcode: 2022NewA...9701859N. 
  7. ↑ Planquart, Léa; Jorissen, Alain; Van Winckel, Hans (2025). "Resolving the mass transfer in the symbiotic recurrent nova T Coronae Borealis". Astronomy and Astrophysics (EDP Sciences) 694: A85. doi:10.1051/0004-6361/202452833. CODEN AAEJAF. ISSN 0004-6361. OCLC 1518497. Bibcode: 2025A&A...694A..85P. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 Hinkle, Kenneth H.; Nagarajan, Pranav; Fekel, Francis C.; Mikołajewska, Joanna; Straniero, Oscar; Muterspaugh, Matthew W. (2025). "Binary Parameters for the Recurrent Nova T Coronae Borealis". The Astrophysical Journal (IOP Publishing) 983 (1): 76. doi:10.3847/1538-4357/adbe63. ISSN 1538-4357. Bibcode: 2025ApJ...983...76H. 
  9. ↑ Schlindwein, Wagner; Baptista, Raymundo; Luna, Gerardo Juan Manuel (2025). "Modeling the High-brightness State of the Recurrent Nova T CRB as an Enhanced Mass-transfer Event". The Astrophysical Journal (IOP Publishing) 989 (1): 78. doi:10.3847/1538-4357/ade98c. ISSN 1538-4357. Bibcode: 2025ApJ...989...78S. 
  10. ↑ 10.0 10.1 10.2 Stanishev, V.; Zamanov, R.; Tomov, N.; Marziani, P. (2004). "Hα variability of the recurrent nova T Coronae Borealis". Astronomy and Astrophysics (EDP Sciences) 415 (2): 609–616. doi:10.1051/0004-6361:20034623. CODEN AAEJAF. ISSN 0004-6361. OCLC 1518497. Bibcode: 2004A&A...415..609S. 
  11. ↑ 11.0 11.1 "T CrB". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=T+CrB. 
  12. ↑ Andrews, Robin George (8 March 2024). "The Night Sky Will Soon Get 'a New Star.' Here's How to See It.". The New York Times. ISSN 1553-8095. OCLC 1645522. Archived from the original on 8 March 2024. https://archive.today/20240308220630/https://www.nytimes.com/article/nova-new-star-t-coronae-borealis.html. Retrieved 9 March 2024. 
  13. ↑ Pettit, Edison (1946). "The Light-Curves of T Coronae Borealis". Publications of the Astronomical Society of the Pacific 58 (341): 153. doi:10.1086/125797. ISSN 1538-3873. OCLC 40768120. Bibcode: 1946PASP...58..153P. 
  14. ↑ Barnard, E. E. (1907). "Nova T Coronae of 1866". Astrophysical Journal (University of Chicago Press) 25: 279. doi:10.1086/141446. ISSN 0004-637X. Bibcode: 1907ApJ....25..279B. 
  15. ↑ Schaefer, Bradley E. (16 November 2023). Evans, James. ed. "The recurrent nova T CrB had prior eruptions observed near December 1787 and October 1217 AD" (in en). Journal for the History of Astronomy (SAGE Publishing) 54 (4): 436–455. doi:10.1177/00218286231200492. ISSN 0021-8286. OCLC 645363374. Bibcode: 2023JHA....54..436S. 
  16. ↑ Thompson, Joanna (September 15, 2023). "Evidence of mysterious 'recurring nova' that could reappear in 2024 found in medieval manuscript from 1217". Future plc. https://www.livescience.com/space/astronomy/evidence-of-mysterious-recurring-nova-that-could-reappear-in-2024-found-in-medieval-manuscript-from-1217. 
  17. ↑ Morelle, Rebecca; Francis, Alison (30 Dec 2024). "Astronomers ready for dazzling but brief celestial show after 80-year wait". https://www.bbc.com/news/articles/c140exemgk7o. 
  18. ↑ Starrfield, Sumner; Bose, Maitrayee; Woodward, Charles E.; Perron, Isabelle; Shaw, Gargi; Evans, Aneurin; Iliadis, Christian; Hix, W. Raphael (2024-06-01). "The evolution leading to a thermonuclear runaway". Bulletin of the American Astronomical Society 56 (7): 132.01. ISSN 0002-7537. OCLC 1479434. Bibcode: 2024AAS...24413201S. 
  19. ↑ Proctor, Mary (June 1897). "Heavens for June". Popular Astronomy 5: 104–105. Bibcode: 1897PA......5...97P. 
  20. ↑ "IAU Catalog of Star Names". https://exopla.net/star-names/modern-iau-star-names/. 
  21. ↑ Sanford, Roscoe F. (1949). "High-Dispersion Spectrograms of T Coronae Borealis.". Astrophysical Journal (University of Chicago Press) 109: 81. doi:10.1086/145106. ISSN 0004-637X. Bibcode: 1949ApJ...109...81S. 
  22. ↑ Schaefer, Bradley E. (2010). "Comprehensive Photometric Histories of All Known Galactic Recurrent Novae". The Astrophysical Journal Supplement Series (IOP Publishing) 187 (2): 275–373. doi:10.1088/0067-0049/187/2/275. Bibcode: 2010ApJS..187..275S. 
  23. ↑ "Vmag<2.5". https://simbad.u-strasbg.fr/simbad/sim-sam?Criteria=Vmag%3C2.5&OutputMode=LIST. Retrieved 2010-06-25. 
  24. ↑ Linford, Justin D.; Chomiuk, Laura; Sokoloski, Jennifer L.; Weston, Jennifer H. S.; Van Der Horst, Alexander J.; Mukai, Koji; Barrett, Paul; Mioduszewski, Amy J. et al. (2019). "T CRB: Radio Observations during the 2016-2017 "Super-active" State". The Astrophysical Journal (IOP Publishing) 884 (1): 8. doi:10.3847/1538-4357/ab3c62. ISSN 1538-4357. Bibcode: 2019ApJ...884....8L. 
  25. ↑ 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. doi:10.1093/mnras/stw1837. Bibcode: 2016MNRAS.462.2695I. 
  26. ↑ Luna, GJM; Mukai, K.; Sokoloski, J. L.; Nelson, T.; Kuin, P.; Segreto, A.; Cusumano, G.; Jaque Arancibia, M. et al. (2018). "Dramatic change in the boundary layer in the symbiotic recurrent nova T Coronae Borealis". Astronomy and Astrophysics (EDP Sciences) 619 (1): 61. doi:10.1051/0004-6361/201833747. CODEN AAEJAF. ISSN 0004-6361. OCLC 1518497. Bibcode: 2018A&A...619A..61L. 
  27. ↑ King, Bob (20 April 2016). "Is T CrB About to Blow its Top?". in Tyson, Peter. F+W Media. https://www.skyandtelescope.com/observing/whats-up-with-t-crb04202016. 
  28. ↑ Schaefer, B.E.; Kloppenborg, B.; Waagen, E.O. (n.d.). "Announcing T CrB pre-eruption dip". https://www.aavso.org/news/t-crb-pre-eruption-dip. 
  29. ↑ 29.0 29.1 Pearson, Ezzy; Lintott, Chris (23 June 2025). "T Coronae Borealis 'Blaze Star' nova event". Immediate Media. https://www.skyatnightmagazine.com/space-science/t-coronae-borealis-nova. 
  30. ↑ Ridgeway, Beth (2024-06-06). "NASA, Global Astronomers Await Rare Nova Explosion" (in en-US). NASA. https://www.nasa.gov/centers-and-facilities/marshall/nasa-global-astronomers-await-rare-nova-explosion/. 
  31. ↑ Shears, J. H. (2024-06-01). "An Independent Discovery of the 1946 Eruption of the Recurrent Nova T Coronae Borealis and an Early Prediction of a Future Outburst". Research Notes of the American Astronomical Society 8 (6): 157. doi:10.3847/2515-5172/ad566b. ISSN 2515-5172. Bibcode: 2024RNAAS...8..157S. 
  32. ↑ Schaefer, Bradley E. (2023-09-01). "The B & V light curves for recurrent nova T CrB from 1842-2022, the unique pre- and post-eruption high-states, the complex period changes, and the upcoming eruption in 2025.5 ± 1.3". Monthly Notices of the Royal Astronomical Society 524 (2): 3146–3165. doi:10.1093/mnras/stad735. ISSN 0035-8711. Bibcode: 2023MNRAS.524.3146S. 
  33. ↑ Schaefer, Bradley E.; Kloppenborg, Brian; Waagen, Elizabeth O. (2023-06-01). "Recurrent nova T CrB has just started its Pre-eruption Dip in March/April 2023, so the eruption should occur around 2024.4 +- 0.3". The Astronomer's Telegram 16107: 1. Bibcode: 2023ATel16107....1S. 
  34. ↑ Maslennikova, N. A.; Tatarnikov, A. M.; Tatarnikova, A. A.; Dodin, A. V.; Shenavrin, V. I.; Burlak, M. A.; Zheltoukhov, S. G.; Strakhov, I. A. (2023-10-01). "Recurrent Symbiotic Nova T Coronae Borealis before Outburst". Astronomy Letters 49 (9): 501–515. doi:10.1134/S1063773723090037. ISSN 1063-7737. Bibcode: 2023AstL...49..501M. 
  35. ↑ Toalá, Jesús A.; González-Martín, Omaira; Sacchi, Andrea; Vasquez-Torres, Diego A. (2024-08-01). "The X-ray rise and fall of the symbiotic recurrent nova system T CrB". Monthly Notices of the Royal Astronomical Society 532 (2): 1421–1433. doi:10.1093/mnras/stae1579. ISSN 0035-8711. Bibcode: 2024MNRAS.532.1421T. 
  36. ↑ Schneider, Jean (October 2024). "When will the Next T CrB Eruption Occur?" (in en). Research Notes of the American Astronomical Society 8 (10): 272. doi:10.3847/2515-5172/ad8bba. ISSN 2515-5172. Bibcode: 2024RNAAS...8..272S. 

Further reading

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