T Pyxidis
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Pyxis |
| Right ascension | 09h 04m 41.50s |
| Declination | −32° 22′ 47.5″ |
| Apparent magnitude (V) | 6.4-15.5 |
| Characteristics | |
| Spectral type | White Dwarf |
| Variable type | Recurrent nova |
| Details | |
| White dwarf | |
| Mass | 0.7±0.2 M☉ |
| Second component | |
| Mass | 0.14±0.03 M☉ |
| Orbit | |
| Period (P) | 1.8295 hours |
| Inclination (i) | 10±2° |
| Other designations | |
|
Nova Pyx 1890, 2MASS J09044150-3222474
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|
| Database references | |
| SIMBAD | data |
T Pyxidis (T Pyx) is a recurrent nova and nova remnant in the constellation Pyxis. It is a binary star system and its distance is estimated at about 4,783 parsecs (15,600 light-years) from Earth. It contains a Sun-like star and a white dwarf. Because of their close proximity and the larger mass of the white dwarf, the latter draws matter from the larger, less massive star. The influx of matter on the white dwarf's surface causes periodic thermonuclear explosions to occur.
The usual apparent magnitude of this star system is 15.5, but there occurred eruptions with maximal apparent magnitude of about 7.0 in the years 1890, 1902, 1920, 1944, 1966 and 2011. Evidence seems to indicate that T Pyxidis may have increased in mass despite the nova eruptions, and is now close to the Chandrasekhar limit when it might explode as a supernova. When a white dwarf reaches this limit it will collapse under its own weight and cause a type 1a supernova.
Because of its relative proximity, some—in particular, Edward Sion, astronomer & astrophysicist at Villanova University, and his team therefrom—contend that a type 1a supernova could have a significant impact on Earth. The received gamma radiation would equal the total (all spectra) radiation of approximately 1,000 solar flares, but the type Ia supernova would have to be closer than 1,000 parsecs (3,300 light-years) to cause significant damage to the ozone layer, and perhaps closer than 500 parsecs. The X-radiation that reaches Earth in such an event, however, would be less than the X-radiation of a single average solar flare.
However, Sion's calculations were challenged by Alex Filippenko of the University of California at Berkeley who said that Sion had possibly miscalculated the damage that could be caused by a T Pyxidis supernova. He had used data for a far more deadly gamma-ray burst (GRB) occurring 1 kiloparsec from Earth, not a supernova, and T Pyxidis certainly is not expected to produce a GRB. According to another expert, "[a] supernova would have to be 10 times closer [to Earth] to do the damage described."Mankind survived when the Crab Nebula supernova went off at a distance of about 6,500 light-years in the year 1054. If this star were to explode as a type Ia supernova at its estimated distance of 3,300 light-years, it would have an apparent magnitude of around -9.3, about as bright as the brightest Iridium (satellite) flares.
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