June 4, 2013
Hubble Helps Astronomers Map Ejected Supernova Material In 3D
Lee Rannals for redOrbit.com — Your Universe Online
Astronomers using NASA's Hubble Space Telescope have mapped out a 3D structure of material ejected from an exploding star.
The team used the space observatory to look at the light emitted by the close double-star system T-Pyxidis, which is a recurring nova. A nova erupts when a white dwarf has siphoned off enough hydrogen from a companion star to trigger a thermonuclear runaway. As the gas builds up on the surface of the star, it becomes hotter and denser until it detonates like a hydrogen bomb.
Astronomers were surprised to find the ejecta from earlier outbursts stayed in the vicinity of the star and formed a disk of debris around the nova. This discovery suggests that material continues expanding along the system's orbital plane, instead of escaping the system.
"We fully expected this to be a spherical shell," says Arlin Crotts of Columbia University, a member of the research team. "This observation shows it is a disk, and it is populated with fast-moving ejecta from previous outbursts."
The team suggests their data indicates the companion star plays an important role in shaping how material is ejected, presumably along the system's orbital plane. They used Hubble's Wide Field Camera 3 to image the blast of light emitted by the erupting nova in April 2011 and traced the light's path. They said the disk is so vast that the light cannot illuminate all of the material at once, but instead sweeps across the material.
"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," team member Stephen Lawrence of Hofstra University said. "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."
This is the first time the immediate environment around an erupting star has been studied in three dimensions. Astronomers have studied light echoes from other novae, but those phenomena illuminated interstellar material around the stars instead of material ejected from them.
The team used the light echo to refine estimates of the nova's distance from Earth and found that it sits 15,600 light-years away from our planet. Previous estimates showed it to be anywhere between 6,000 to 16,000 light years away.