Featured Research

from universities, journals, and other organizations

Celestial Rosetta Stone: White Dwarf Star, Circling Companion Star, Could Explode In A Few Million Years

Date:
September 4, 2009
Source:
European Space Agency
Summary:
The European Space Agency's XMM-Newton orbiting X-ray telescope has uncovered a celestial Rosetta stone: the first close-up of a white dwarf star, circling a companion star, that could explode into a particular kind of supernova in a few million years. These supernovae are used as beacons to measure cosmic distances and ultimately understand the expansion of our Universe.

Illustration of the white dwarf and its companion HD49798. If it was possible to look at the system up-close, it would look something like this.
Credit: Francesco Mereghetti, background image: NASA, ESA and T.M. Brown (STScI)

ESA's XMM-Newton orbiting X-ray telescope has uncovered a celestial Rosetta stone: the first close-up of a white dwarf star, circling a companion star, that could explode into a particular kind of supernova in a few million years. These supernovae are used as beacons to measure cosmic distances and ultimately understand the expansion of our Universe.

Astronomers have been on the trail of this mysterious object since 1997, when they discovered that something was giving off X-rays near the bright star HD 49798. Now, thanks to XMM-Newton's superior sensitivity, the mysterious object has been tracked along its orbit. The observation has shown it to be a white dwarf, the dead heart of a star, shining X-rays into space.

Sandro Mereghetti, INAF–IASF Milano, Italy, and collaborators also discovered that this is no ordinary white dwarf. They measured its mass and found it to be more than twice what they were expecting. Most white dwarfs pack 0.6 solar masses into an object the size of Earth. This particular white dwarf contains at least double that mass but has a diameter just half that of Earth. It also rotates once every 13 seconds, the fastest of any known white dwarf.

The mass determination is reliable because the XMM-Newton tracking data allowed the astronomers to use the most robust method for 'weighing' a star, one that uses the gravitational physics devised by Isaac Newton in the 17th century. Most likely, the white dwarf has grown to its unusual mass by stealing gas from its companion star, a process known as accretion. At 1.3 solar masses, the white dwarf is now close to a dangerous limit.

When it grows larger than 1.4 solar masses, a white dwarf is thought either to explode or collapse to form an even more compact object called a neutron star. The explosion of a white dwarf is the leading explanation for 'type Ia supernovae', bright events that are used as standard beacons by astronomers to measure the expansion of the Universe. Until now, astronomers have not been able to find an accreting white dwarf in a binary system where the mass could be determined so accurately.

"This is the Rosetta stone of white dwarfs in binary systems. Our precise determination of the masses of the two stars is crucial. We can now study it further and try to reconstruct its past, so that we can calculate its future," says Mereghetti.

That future is a spectacular one. The star is likely to explode in a few million years' time. Although it is far enough to pose no danger to Earth, it is close enough to become an extraordinarily spectacular celestial sight. Calculations suggest that it will blaze initially with the intensity of the full Moon and be so bright that it will be seen in the daytime sky with the naked eye.

Our descendants are in for quite a show. Thanks to XMM-Newton, we can already start looking forward to it.


Story Source:

The above story is based on materials provided by European Space Agency. Note: Materials may be edited for content and length.


Cite This Page:

European Space Agency. "Celestial Rosetta Stone: White Dwarf Star, Circling Companion Star, Could Explode In A Few Million Years." ScienceDaily. ScienceDaily, 4 September 2009. <www.sciencedaily.com/releases/2009/09/090903163852.htm>.
European Space Agency. (2009, September 4). Celestial Rosetta Stone: White Dwarf Star, Circling Companion Star, Could Explode In A Few Million Years. ScienceDaily. Retrieved April 17, 2014 from www.sciencedaily.com/releases/2009/09/090903163852.htm
European Space Agency. "Celestial Rosetta Stone: White Dwarf Star, Circling Companion Star, Could Explode In A Few Million Years." ScienceDaily. www.sciencedaily.com/releases/2009/09/090903163852.htm (accessed April 17, 2014).

Share This



More Space & Time News

Thursday, April 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

New Baby Moon 'Peggy' Spotted In Saturn's Rings

New Baby Moon 'Peggy' Spotted In Saturn's Rings

Newsy (Apr. 15, 2014) A bump in the rings could be a half-mile-wide miniature moon. It was found by accident in Cassini probe images. Video provided by Newsy
Powered by NewsLook.com
Americas Glimpse Total Lunar Eclipse

Americas Glimpse Total Lunar Eclipse

AFP (Apr. 15, 2014) A total lunar eclipse, the first since December 2011, took place early Tuesday morning with the Americas getting the best glimpse. Duration: 1:19 Video provided by AFP
Powered by NewsLook.com
NASA Showcases Lunar Eclipse

NASA Showcases Lunar Eclipse

AP (Apr. 15, 2014) Star gazers in parts of North and South America got a rare treat early Tuesday morning - a total eclipse of the moon. (April 15) Video provided by AP
Powered by NewsLook.com
Spacecrafts Could Use Urine As Fuel Source

Spacecrafts Could Use Urine As Fuel Source

Newsy (Apr. 15, 2014) New research says the urea from urine could be recycled for fuel. Urea is filtered out of wastewater when making drinking water. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins