V838 Monocerotis
Hubble Space Telescope image of V838 Monocerotis and the surrounding nebula on September 9, 2006 Credit: NASA/ESA | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Monoceros |
| Right ascension | 07h 04m 04.822s |
| Declination | −03° 50′ 50.53″ |
| Apparent magnitude (V) | 6.75 (2002), 15.6 |
| Characteristics | |
| Evolutionary stage | M-type supergiant |
| Spectral type | M7.5I -> M5.5I + B3V |
| Variable type | LRN |
| Astrometry | |
| Proper motion (μ) | RA: −0.536±0.229 mas/yr Dec.: −0.078±0.174 mas/yr |
| Parallax (π) | 0.163±0.016 mas |
| Distance | 19,200 ly (5,900±400 pc) |
| Details | |
| Mass | 5 – 10 M☉ |
| Radius | 464 R☉ |
| Luminosity | 23,000 L☉ |
| Temperature | 3,300 K |
| Age | 4 Myr |
| Other designations | |
| V838 Mon, Nova Monocerotis 2002, GSC 04822-00039 | |
| Database references | |
| SIMBAD | data |
V838 Monocerotis (Nova Monocerotis 2002) is a cataclysmic binary star in the constellation Monoceros about 19,000 light years (6 kpc) from the Sun. The previously unremarked star was observed in early 2002 experiencing a major outburst, and was one of the largest known stars for a short period following the outburst. Originally believed to be a typical nova eruption, it was then identified as the first of a new class of eruptive variables known as luminous red novae. The reason for the outburst is still uncertain, but is thought to have been a merger of two stars within a triple system.
The eruption occurred on one of two B3 main sequence stars in a close binary orbit. The erupting star appeared as an unusually cool supergiant and for a while engulfed its companion. By 2009 the temperature of the supergiant had increased (since 2005) to 3,270 K and its luminosity was 15,000 times solar (L☉), but its radius had decreased to 380 times that of the Sun (R☉), although the ejecta continues to expand.