Featured Research

from universities, journals, and other organizations

A Sub-stellar Jonah: Brown Dwarf Survives Being Swallowed

Date:
August 14, 2006
Source:
European Southern Observatory
Summary:
Using ESO's Very Large Telescope, astronomers have discovered a rather unusual system, in which two planet-size stars, of different colors, orbit each other. One is a rather hot white dwarf, weighing a little bit less than half as much as the Sun. The other is a much cooler, 55 Jupiter-masses brown dwarf.

Computer simulation of the merger process of a Red Giant with a Brown Dwarf that leads to the white dwarf/brown dwarf binary system containing WD0137-349. The simulation was done by Los Alamos National Laboratory's members Steven Diehl, Chris Fryer, Falk Herwig, and Gabriel Rockefeller.
Credit: Image courtesy of European Southern Observatory

Using ESO's Very Large Telescope, astronomers have discovered a rather unusual system, in which two planet-size stars, of different colours, orbit each other. One is a rather hot white dwarf, weighing a little bit less than half as much as the Sun. The other is a much cooler, 55 Jupiter-masses brown dwarf.

"Such a system must have had a very troubled history", said Pierre Maxted, lead author of the paper that reports the study in this week's issue of Nature. "Its existence proves that the brown dwarf came out almost unaltered from an episode in which it was swallowed by a red giant."

The two objects, separated by less than 2/3 of the radius of the Sun or only a few thousandths of the distance between the Earth and the Sun, rotate around each other in about 2 hours. The brown dwarf [1] moves on its orbit at the amazing speed of 800 000 km/h!

The two stars were not so close in their past. Only when the solar-like star that has now become a white dwarf [2] was a red giant, did the separation between the two objects diminish drastically. During this fleeting moment, the giant engulfed its companion. The latter, feeling a large drag similar to trying to swim in a bath full of oil, spiralled in towards the core of the giant. The envelope of the giant was finally ejected, leaving a binary system in which the companion is in a close orbit around a white dwarf.

"Had the companion been less than 20 Jupiter masses, it would have evaporated during this phase", said Maxted."

The brown dwarf shouldn't rejoice too quickly to have escaped this doom, however. Einstein's General Theory of Relativity predicts that the separation between the two stars will slowly decrease.

"Thus, in about 1.4 billion years, the orbital period will have decreased to slightly more than one hour", said Ralf Napiwotzki, from the University of Hertfordshire (UK) and co-author of the study. "At that stage, the two objects will be so close that the white dwarf will work as a giant "vacuum cleaner", drawing gas off its companion, in a cosmic cannibal act."

The low mass companion to the white dwarf (named WD0137-349) was found using spectra taken with EMMI at ESO's New Technology Telescope at La Silla. The astronomers then used the UVES spectrograph on ESO's Very Large Telescope to record 20 spectra and so measure the period and the mass ratio.

Notes

[1]: Brown dwarfs are 'failed stars' that have less than 75 Jupiter masses and are unable to sustain nuclear fusion in their core.

[2]: White dwarfs are Earth-size, hot and extremely dense stars that represent the end products of the evolution of solar-like stars. During most of their life, such stars draw most of their energy from the transformation of hydrogen into helium. But at some moment, the hydrogen fuel will run out: this phase - still many billions of years into the future for the Sun - signals the beginning of profound, increasingly rapid changes in the star which will ultimately lead to its death. The star dramatically increases in radius, becoming a red giant. Later, it will expel huge quantity of gas and appear as a planetary nebula. Once the planetary nebula has dissolved, one is left with a white dwarf.


Story Source:

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


Cite This Page:

European Southern Observatory. "A Sub-stellar Jonah: Brown Dwarf Survives Being Swallowed." ScienceDaily. ScienceDaily, 14 August 2006. <www.sciencedaily.com/releases/2006/08/060814115617.htm>.
European Southern Observatory. (2006, August 14). A Sub-stellar Jonah: Brown Dwarf Survives Being Swallowed. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2006/08/060814115617.htm
European Southern Observatory. "A Sub-stellar Jonah: Brown Dwarf Survives Being Swallowed." ScienceDaily. www.sciencedaily.com/releases/2006/08/060814115617.htm (accessed July 31, 2014).

Share This




More Space & Time News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Supply Ship Takes Off for International Space Station

Supply Ship Takes Off for International Space Station

AFP (July 30, 2014) The European Space Agency's fifth Automated Transfer Vehicle (ATV-5) is takes off to the International Space Station on an Ariane 5 rocket from French Guiana. Duration: 00:34 Video provided by AFP
Powered by NewsLook.com
Raw: Rocket Launches Into Space With Cargo Ship

Raw: Rocket Launches Into Space With Cargo Ship

AP (July 30, 2014) Arianespace launched a rocket Tuesday from French Guiana carrying a robotic cargo ship to deliver provisions to the International Space Station. (July 30) Video provided by AP
Powered by NewsLook.com
In Virginia, the Rise of a New Space Coast

In Virginia, the Rise of a New Space Coast

AP (July 30, 2014) Every summer, tourists make the pilgrimage to Chincoteague Island, Va. to see wild ponies cross the Assateague Channel. But, it's the rockets sending to supplies to the International Space Station that are making this a year-round destination. (July 30) Video provided by AP
Powered by NewsLook.com
Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Newsy (July 27, 2014) The satellite is back under ground control after a tense few days, but with a gecko sex experiment on board, the media just couldn't help themselves. 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