When Stars Go Nova, Shocks Cook the Stellar Neighborhood

In 1901, the star GK Persei became a surprise astronomical sensation. Out of the dark, it rapidly brightened, becoming the brightest star in the sky for several days. But it wasn’t a supernova; the stellar spectacle was a lesser explosion that nonetheless is still having a significant impact on local space.

The explosion of GK Persei was triggered by the buildup of hot plasma on the surface of a white dwarf star. The small, dense object had been siphoning the gas from a binary partner. When the plasma reached a critical mass, a powerful thermonuclear explosion ripped through the upper layers of the white dwarf.

This explosion, however, did not destroy the white dwarf and was therefore not a “supernova;” it was a “classical nova.”

The result of a classical nova is a rapidly brightening orb of hot gas and interstellar shock waves that leave the progenitor star intact — a mini-supernova of sorts. Although novae do not create the heavy elements that supernovae are known to generate, seeding the galaxy with elements like iron, calcium and oxygen, novae like GK Persei can still have dramatic effects on surrounding space.

Now, NASA’s Chandra X-ray Observatory has gathered the results of observations it carried out in February 2000 and then again in November 2013. Over a century later, GK Persei still resembles an expanding mess of hot material, but by having two sets of observations 13 years apart, short-term changes in the nova debris can be seen.

Chandra has clocked the clumps of gas blasting away from the point of detonation at 700,000 miles per hour — meaning the blast wave has traveled 90 billion miles (nearly 1,000 astronomical units) over those 13 years.

Over the same period, the luminosity of the material has obviously decreased (by 40 percent), but of particular interest is the temperature of the surrounding interstellar gases — the temperature has remained constant, which is peculiar.

Read more at Discovery News