Hubble Maps 3D Image of Ejected Material Around a Stellar Outburst

Astronomers used NASA’s Hubble Space Telescope to observe a flash of light from a stellar outburst that has provided a rare look at the 3D structure of material ejected by an erupting nova, according to a statement issued on the telescope’s website.

Known as T Pyx, the double-star system is a recurring nova with the last outburst having occurred in April 2011.

In researching the event, the astronomers were surprised to find that the debris ejected from earlier outbursts stayed in the same region of the star, forming a disk around the nova.

This discovery, according to the scientists, suggests that while the material continues expanding outward along the system’s orbital plane, it does not escape the system.

“We fully expected this to be a spherical shell,” Arlin Crotts of Columbia University and a member of the research team said. “This observation shows it is a disk, and it is populated with fast-moving ejecta from previous outbursts.”

Also from Columbia, team member Jennifer Sokoloski suggests that these data indicate the companion star plays an important role in shaping how material is ejected, presumably along the system’s orbital plane, creating the pancake-shaped disk that is currently tilted approximately 30 degrees from face-on toward Earth.

At this point, based on the researchers’ recent observations, the disk is so vast (about a light-year across) that the nova’s light cannot illuminate all of it at once; instead, the light sweeps past the material, creating a light echo in which the parts are illuminated in sequential order.

And while astronomers have seen light moving through material surrounding other novae, this opportunity represents the first time they will be able to observe the immediate environment around an erupting star in three dimensions.

"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."

A nova occurs when a white dwarf, the burned-out core of a sun-like star, steals enough hydrogen from a companion star to trigger a thermonuclear runaway. As hydrogen builds up on its surface, it becomes hotter and denser until it detonates, leading to a 10,000-fold increase in brightness in a little more than one day.

In all, a nova explosion is approximately equal to a blast of 1 million billion tons of dynamite, according to the researchers.