Detected by American astronomer Michael Linnolt in Hawaii on April 14 (technically April 14.2931), binary star T Pyxidis finally exploded again. After out-bursting last in December of 1966, forty-five years ago; T Pyxidis was very overdue (on exploding) and reached magnitude 8.4 on April 14, 2011 although in 1996-7 it reached 6.5, much brighter than its present state. Τo view this event; look for T Pyxidis in the dim constellation Pyxis, "the Mariner's compass box," east of Puppis and Canis Major. (America rarely is able to view the constellation, but the Southern Hemisphere is able to). Thanks to AAVSO (the American Association of Variable Star Observation) we are given the exact declination: -32 22 47.4 degrees and currently lies high in the sky after dusk in the south-southwest sky.
Images from ground telescopes and the Hubble Space telescope; you can view the white dwarf surrounded in matter accumulated by the Sun-like star.
However, T Pyxidis' history is very interesting; needless to say its future is as well. The first explosion was observed in 1890; it continued to explode [around] every twenty years: again in 1902, 1920, 1944, and 1966-7. You can now see this was an extremely overdue out-bursting, and no-one knows why it stopped its explosions for the pause of forty-five years: 1966-7 to 2011. T Pyxidis will remain about at magnitude seven or eight for about two months (as recorded before), so viewing until June will be at its best.
T Pyxidis is located approximately 3300 light-years from earth in the constellation Pyxis, hence the name 'Pyxidis.' It is a binary star system, which is comprised of a prominent white-dwarf, and a lesser Sun-like star orbiting around each other. (Most of the stars in the universe are not single; our Sun is actually very special: it has no companion). The reason why T Pyxidis periodically explodes is simple: the white dwarf has a strong gravitational pull on the Sun-like star and pulls matter (specifically hydrogen-rich gases) from the other resulting in a periodic thermonuclear explosion. This thermonuclear explosion was the one observed these past (including 2011) six times.
An article entitled T Pyxidis Soon To Be A Type Ia Supernova, published January 5, 2010, tells us: "An extremely important unanswered question about such close binary stars is whether the mass receiving white dwarf continually grows in mass despite the nova explosions or decreases in mass because the nova explosions eject more mass from the white dwarf than it accumulates from the Sun-like star." Regularly viewed, the system is about magnitude 15.5 (the naked, human eye can detect up to magnitude six), and hasn't gone any brighter since 1966-7, until 2011. Thoughts are, is that this star (or these stars) will explode on itself (only one star of the system will) in the next ten millenia or so, resulting in T Pyxidis becoming a Type Ia Supernova.
This summons the issue of being a threat to earth. Type Ia supernovae are extremely dramatic: "If the mass of the white dwarf in such a binary star system increases with time, then it will eventually reach the so-called Chandrasekhar Limit and will undergo instantaneous gravitational collapse resulting in an unimaginably powerful thermonuclear detonation which completely destroys the white dwarf and leaves no stellar remnant such as a pulsar (i.e., spinning neutron star) or a black hole." Space Daily tells us. (If this occurs,) because about twenty billion, billion, billion megatons of TNT would be released, if it would ever become a Type Ia supernova, earth would sure feel an effect of its explosion. T Pyxidis is closer to earth than astronomers had reasoned; the gamma radiation formed by such an explosion would fry earth. Astronomers are also watching Eta Carinae (7500 light years from earth) also. It is too a remnant that could do the same as T Pyxidis. But, this event (with T Pyxidis) won't or couln't happen until ten million years into the future. Edward Sion, researcher at Villanova University, tells us that "While we can relax, that is very short on astronomical and geological timescales." (Note: it is short on evolutionary/'big-bang theory' timescales, NOT creationism timescales).
So, if whether T Pyxidis decides to explode in on itself, we don't know. We have observed many other supernovae explosions, but are a safe distance from earth. T Pyxidis is a remarkable binary!
To view T Pyxidis' explosion April 15th, you can view a quick double-image on this page. (Note: T Pyxidis explodes in the center, not at the top.) Below; how a Type Ia supernova forms.
[~Matthew Winter~]
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