T Coronae Borealis (HD 143454 / The Blaze Star)
Coordinates, Gaia DR3 distance (916 pc), 227.57-day symbiotic M4 III + 1.37-M☉ white dwarf orbit, 80-year recurrent nova cycle, and guide for T CrB.
Provenance-Backed Scientific Measurements
Every measurement below preserves its unit, uncertainty interval, observational method, reference epoch, quality status, and primary catalog source. See Uncertainty & Provenance for how competing measurements are handled.
| Parameter | Value | Uncertainty | Method & Epoch | Quality Status | Source Archive |
|---|---|---|---|---|---|
| Quiescent vs outburst visual magnitude (V) | 10 mag | ± 0.3 mag | AAVSO photometry (quiescent V = 9.8–10.6; erupts to V = 2.0 during thermonuclear nova outbursts!) | definitive | SIMBAD Astronomical Database (CDS) |
| Trigonometric distance (Gaia DR3) | 916 pc | ± 23 pc | Gaia DR3 astrometric parallax (1.092 ± 0.028 mas / 2,988 ± 75 ly) (J2016.0) | definitive | ESA Gaia Archive — Data Release 3 |
| Symbiotic binary orbital period | 227.5687 d | ± 0.002 d | Radial-velocity & ellipsoidal light curve (0.54 AU separation) | definitive | SIMBAD Astronomical Database (CDS) |
| White dwarf mass (near Chandrasekhar limit) | 1.37 M☉ | ± 0.02 M☉ | Spectroscopic + ellipsoidal modeling (Stanishev et al. 2004; M4 III giant = 1.12 ± 0.23 M☉) | high-confidence | SIMBAD Astronomical Database (CDS) |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots T Coronae Borealis (The Blaze Star Nova) at RA 15h 59m 30.16s, Dec +25° 55′ 12.6″ within Corona Borealis, alongside peak meridian transit altitudes for 40°N and 30°S observers. Use the RA/Dec Coordinate Converter to compute exact culmination altitude for your latitude.
Astrophysical Context & Structure
T Coronae Borealis (T CrB, HD 143454, famously known as 'the Blaze Star') is the brightest recurrent nova in Earth's sky and one of only ~11 recurrent novae known in the Milky Way. Lying 916 ± 23 parsecs (2,988 light-years) away just 1° southeast of Epsilon Coronae Borealis on the outer rim of the Northern Crown, T CrB normally slumbers for ~80 years as a 10.0-magnitude star invisible to the naked eye—until it suddenly detonates in a thermonuclear flash that surges 1,500-fold in brightness up to magnitude 2.0 (matching Alphecca, the brightest star in the Crown) within hours!
Historical records document eruptions in May 1866 (discovered by John Birmingham) and February 1946 (plus medieval accounts suggesting earlier outbursts in 1217 and 1787). Unlike a single-star variable, T CrB is a symbiotic interacting binary with a 227.57-day orbital period (semi-major axis 0.54 AU): a bloated ~75-solar-radius M4.5 III red giant fills its Roche lobe and funnels hydrogen gas onto an ultra-massive, Earth-sized carbon-oxygen white dwarf weighing 1.37 ± 0.02 solar masses—perilously close to the 1.40-solar-mass Chandrasekhar limit for a Type Ia supernova.
Because the surface gravity on a 1.37-solar-mass white dwarf is so crushing, it takes only ~80 years of accretion to compress the freshly accumulated hydrogen blanket to the critical ignition temperature (~20 million K) for a runaway CNO-cycle thermonuclear flash. The explosion blasts off the accreted shell at >4,000 km/s without destroying the white dwarf, causing the star to shine at 2nd magnitude for only 3 to 5 days before fading back to 10th magnitude and resetting the 80-year clock.
Practical Visual Observing Guide
- Memorize the semicircular arc of Corona Borealis with the naked eye: T CrB sits 1.0° south-southeast of 4.1-magnitude Epsilon Coronae Borealis (ε CrB), just outside the eastern tip of the Crown.
- In quiescence (magnitude 9.8–10.6, with a 0.3-magnitude ellipsoidal wobble every 114 days as the egg-shaped red giant rotates), T CrB is an easy target in any 60–80 mm telescope or 15×70 binoculars; during its brief thermonuclear eruption, it becomes a 2.0-magnitude naked-eye star reshaping the constellation of Corona Borealis for less than a week!
Catalog Cross-Identifications & Aliases
Common Aliases: T CrB · The Blaze Star · HD 143454 · HIP 78322 · HR 5958
| Catalog Authority | Identifier |
|---|---|
| GAIADR3 | 1220110644551628800 |
| HIP | HIP 78322 |
| HD | HD 143454 |
| SIMBAD | V* T CrB |
| WIKIDATA | Q1334443 |
Related Objects, Comparisons & Guides
R Coronae Borealis (Reverse Nova Carbon Star)
Coordinates, Gaia DR3 distance (1.30 kpc), hydrogen-deficient carbon supergiant, 9-magnitude soot-cloud fade-outs, and observing guide for R CrB.
SS Cygni (Cataclysmic Dwarf Nova Binary)
Coordinates, VLBI/Gaia distance (114 pc), 6.60-hour white-dwarf + K-dwarf orbit, 49-day accretion disk outbursts, and guide for SS Cygni.
Mira (Omicron Ceti Pulsating Giant)
Coordinates, Hipparcos distance (100 pc), 332-day pulsation cycle (mag 2.0 to 10.1), white dwarf companion, and observing guide for Mira.
Apparent vs Absolute Magnitude Explained
Understand the logarithmic Pogson astronomical magnitude scale, apparent visual magnitude (m), absolute magnitude (M at 10 parsecs), and bolometric corrections.
Trigonometric Parallax, Parsecs & Gaia DR3
How trigonometric parallax (d_pc = 1 / p_arcsec), the distance modulus equation, Hipparcos, and Gaia DR3 microarcsecond astrometry measure cosmic distances.
Scientific Sources & Dataset Provenance
- ESA Gaia Archive — Data Release 3 (DR3 (2022-06-13)): Gaia Collaboration, Vallenari, A., et al. 2023, A&A, 674, A1 (Gaia Data Release 3) — European Space Agency / Gaia DPAC
- SIMBAD Astronomical Database (CDS) (2026-10 release): Wenger, M., et al. 2000, A&AS, 143, 9 (The SIMBAD astronomical database) — Centre de Données astronomiques de Strasbourg