APOD and General Astronomy Discussion Forum
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http://en.wikipedia.org/wiki/T_Pyxidis wrote: <<T Pyxidis (T Pyx) is a binary star system in the constellation Pyxis estimated at about 1,000 parsecs (3,300 light-years) from Earth. It contains a sun-like star and a white dwarf. Because of the strong gravity effect of the white dwarf, it draws matter from the other star which causes periodic thermonuclear explosions to occur. T Pyx is a recurrent nova and nova remnant in the constellation Pyxis.
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. T Pyx had not been brighter than magnitude 14 since the 1966 eruption. It could very well be evolving into a new type system and may not erupt again for hundreds of years. 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 a white dwarf reaches this limit it will collapse under its own weight and cause a Type Ia supernova. However, when contacted by Scientific American, Dr Sion said that the term "soon" in the press announcement meant that "At the accretion rate we derived, the white dwarf in T Pyxidis will reach the Chandrasekhar Limit in ten million years." By that time it will have moved far enough away from the solar system to have little effect.
Because of its relatively close distance, some contend that a T Pyxidis supernova could have a significant impact on Earth. The received gamma radiation would equal the total (all spectra) radiation of approximately 1000 solar flares, but a type Ia supernova would have to be closer than 1,000 parsecs to cause significant damage to the ozone layer. The X-radiation that reaches Earth, however, would be less than the X-radiation of a single average solar flare. However, Dr. Sion's calculations were challenged by professor Alex Filippenko 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) exploding 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 went off at a distance of about 6500 light-years in the year 1054. If this star were to explode as a type Ia supernova at its estimated distance of 3300 light-years, it would have an apparent magnitude of around -9.3, about as bright as the brightest Iridium (satellite) flares.
2011 Outburst: Mike Linnolt has detected T Pyx first outburst in nearly 45 years. He detected it on April 14 2011 at magnitude 13. According to AAVSO observers, it has since reached magnitude 7.5 in visual and V bands. T Pyxidis is a super soft X-ray source.>>
