Featured Research

from universities, journals, and other organizations

How white dwarfs mimic black holes

Date:
December 17, 2012
Source:
University of Southampton
Summary:
Astronomers have revealed that bright X-ray flares in nearby galaxies, once assumed to indicate the presence of black holes, can in fact be produced by white dwarfs. They made the discovery by detecting a dramatic, short-lived X-ray flare that was picked up by an X-ray telescope on the International Space Station.

A remarkable observation by astronomers from the University of Southampton, Professor Phil Charles, Professor Malcolm Coe and postgraduate student Liz Bartlett, has appeared in The Astrophysical Journal.

Related Articles


The Southampton Physics and Astronomy team are part of a global collaboration -- with colleagues in Taiwan, South Africa, Poland, Australia and Italy -- that has revealed that bright X-ray flares in nearby galaxies, once assumed to indicate the presence of black holes, can in fact be produced by white dwarfs.

They made the discovery by detecting a dramatic, short-lived X-ray flare that was picked up by an X-ray telescope on the International Space Station.

Using optical telescopes in South Africa and Chile, the Southampton astronomers showed that the flare, called XRF111111 as it happened on 11 November, 2011, was located in the Small Magellanic Cloud. These Magellanic Clouds are between 160,000 and 200,000 light years away and are the nearest satellite galaxies to the Milky Way. They are visible to the naked eye from the Southern Hemisphere.

The flare from XRF111111 was so luminous that astronomers initially thought it was likely to be a black hole producing X-rays but further research by Phil and his team revealed that its X-ray temperature was so low that it had to be a white dwarf instead.

White dwarfs are very common, burnt-out cinders of normal stars like the Sun that are typically about one solar mass but are contained in a volume no bigger than Earth.

However, white dwarfs were not considered capable of producing such a huge X-ray flash but the optical observations in South Africa and Chile showed that the white dwarf was orbiting a hot B star -- a normal star about 10 times the mass of our Sun that is much hotter and brighter. This was something that had only been seen twice previously and both times with much lower X-ray luminosities.

Research by Professor Charles and his team revealed that material was probably collecting on the surface of the white dwarf from the B star and eventually underwent runaway thermonuclear burning that was seen on Earth as a nova explosion.

Professor Charles says: "Our observations show that the thermonuclear burning probably caused a shell of matter to be ejected from around the white dwarf and when the shell hit the hot wind of the B star it produced a huge shock leading to the X-ray flash that was seen on the International Space Station.

"We think that this incredible X-ray flash was not due to accretion onto a black hole but was instead due to a nova explosion on a white dwarf that took place close to a hot massive star. This was something that we, as astronomers, have never seen before.

"This surprising result shows that, in the right circumstances, white dwarfs are capable of mimicking black holes, the most luminous objects we know of."


Story Source:

The above story is based on materials provided by University of Southampton. Note: Materials may be edited for content and length.


Journal Reference:

  1. K. L. Li, Albert K. H. Kong, P. A. Charles, Ting-Ni Lu, E. S. Bartlett, M. J. Coe, V. McBride, A. Rajoelimanana, A. Udalski, N. Masetti, Thomas Franzen. A Luminous Be+ White Dwarf Supersoft Source in the Wing of the SMC: MAXI J0158-744. The Astrophysical Journal, 2012; 761 (2): 99 DOI: 10.1088/0004-637X/761/2/99

Cite This Page:

University of Southampton. "How white dwarfs mimic black holes." ScienceDaily. ScienceDaily, 17 December 2012. <www.sciencedaily.com/releases/2012/12/121217091300.htm>.
University of Southampton. (2012, December 17). How white dwarfs mimic black holes. ScienceDaily. Retrieved November 20, 2014 from www.sciencedaily.com/releases/2012/12/121217091300.htm
University of Southampton. "How white dwarfs mimic black holes." ScienceDaily. www.sciencedaily.com/releases/2012/12/121217091300.htm (accessed November 20, 2014).

Share This


More From ScienceDaily



More Space & Time News

Thursday, November 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Crowdfunded Moon Mission Offers To Store Your Digital Memory

Crowdfunded Moon Mission Offers To Store Your Digital Memory

Newsy (Nov. 19, 2014) Lunar Mission One is offering to send your digital memory (or even your DNA) to the moon to be stored for a billion years. Video provided by Newsy
Powered by NewsLook.com
Accidents Ignite Debate on US Commercial Space Travel

Accidents Ignite Debate on US Commercial Space Travel

AFP (Nov. 19, 2014) Serious accidents with two US commercial spacecraft within a week of each-other in October have re-ignited the debate over the place of private corporations in the exploration of space. Duration: 02:08 Video provided by AFP
Powered by NewsLook.com
Lunar Mission One Could Send Your Hair to The Moon

Lunar Mission One Could Send Your Hair to The Moon

Buzz60 (Nov. 19, 2014) A British-led venture called Lunar Mission One plans to send a module to the moon with keepsakes from Earth. Vanessa Freeman (@VanessaFreeTV) tells you how to get your photos and DNA onboard. Video provided by Buzz60
Powered by NewsLook.com
Why A Russian Object Is Being Called A 'Satellite Killer'

Why A Russian Object Is Being Called A 'Satellite Killer'

Newsy (Nov. 18, 2014) An unidentified Russian spacecraft is getting some attention, with some saying it could be for research while others say it could be a weapon. 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:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

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