Rabu, 12 September 2012

Kepler Supernova Lies Farther Away Than First Thought


The famous Kepler supernova remnant, left behind by a huge blast that occurred in 1604, is apparently more distant than originally estimated. The conclusion belongs to a new study carried out using the NASA Chandra X-Ray Observatory.

When the distant star exploded, it became visible in Earth's night sky, and captured the attention of numerous people. Some saw it as a sign of the apocalypse, but others figured out that they were witnessing a historic event.

Among the latter was the famous astronomer Johannes Kepler, for whom the supernova remnant is now named. Scientists have been following up on his studies ever since, refining measurements and gaining more insight into what actually happened.

This is also why NASA astronomers decided some time ago to use Chandra for a long-term study of the remnant. What they've learned is that this cosmic structure is more distant than originally thought.

The image to the left comprises data collected by the NASA telescope over a period of 8 days, and is color-coded according to wavelength. Red represents the lower energies, while purple the highest.

The background is an optical image collected by the Digitized Sky Survey, providing some context of Kepler Supernova Remnant's location in space. According to astronomers, the stellar explosion was a Type Ia supernova.

What this suggests is that the progenitor star was a white dwarf. Type Ia supernovae occur when such a stellar object merges with another white dwarf, or when it continuously accretes mass from a companion star, until it becomes unstable and blows up.

Until now, astronomers believed that the remnant was located at a distance of around 13,000 light years. The new data suggests that the structure lies between 16,000 and 23,000 light-years away.

Details of how Chandra determined the new values were published in the September 1 issue of the esteemed Astrophysical Journal.

“Unlike other well-known Type Ia supernovas and their remnants, Kepler’s debris field is being strongly shaped by what it is running into,” NASA investigators say.

“More specifically, most Type Ia supernova remnants are very symmetrical, but the Kepler remnant is asymmetrical with a bright arc of X-ray emission in its northern region. This indicates the expanding ball of debris from the supernova explosion is plowing into the gas and dust around the now-dead star,” they conclude.

Via: Kepler Supernova Lies Farther Away Than First Thought

Tidak ada komentar:

Posting Komentar