T Pyx's white dwarf has a companion star, from which it siphons off hydrogen fuel. When enough of this hydrogen builds up on the white dwarf's surface, it detonates like a gigantic hydrogen bomb, increasing the white dwarf's brightness by a factor of 10,000 over a single day or so.
This happens again and again. T Pyx is known to have erupted in 1890, 1902, 1920, 1944, and 1966, in addition to the 2011 event.
Such recurrent outbursts are known as nova explosions. (Nova is Latin for "new," referring to how suddenly novas appear in the sky.) Novas are distinct from supernovas, even more dramatic blasts that involve the destruction of an entire star.
The new study clarifies just what happens to the material ejected by such outbursts.
"We've all seen how light from fireworks shells during the grand finale will light up the smoke and soot from shells earlier in the show," co-author Stephen Lawrence of Hofstra University said in a statement. "In an analogous way, we're using light from T Pyx's latest outburst and its propagation at the speed of light to dissect its fireworks displays from decades past."