Content Starts Here
brown dwarf
Encyclopaedia Search
Brown Dwarf
In astronomy, object less massive than a star but denser than a planet. Brown dwarfs do not have enough mass to ignite nuclear reactions at their centres, but shine by heat released during their contraction from a gas cloud. Groups of brown dwarfs have been discovered, and some astronomers believe that vast numbers of them exist throughout the Galaxy.
The first brown dwarf to be positively identified was Gliese 229B (GI229B), in the constellation Lepus, by US astronomers using images from the Hubble Space Telescope. It is about 50 times as massive as Jupiter but emits only 1% of the radiation of the smallest known star and has a surface temperature of 650°C/1,200°F. Brown dwarfs cannot exist with a mass of greater than 80 times that of Jupiter.
© Research Machines plc 2008. All rights reserved. Helicon Publishing is a division of Research Machines plc.
Advertisement starts
Advertisement ends
Related Links
United States of America Flag
Red stands for hardiness and valour. White signifies purity and innocence. Blue represents vigilance, perseverance, and justice. The latest star, representing Hawaii, was added in 1960. Effective date: 4 July 1960.
>>
Advertorial
Find out how to buy the things you've always wanted and sell the things you don't on ebay.
Advertisement starts
Advertisement ends
Page Footer
Access keys
You will need to use different key combinations in order to use access keys depending on your internet browser, find out which on our accessibility page.
- (0) Navigate to Accessibility page.
- (1) Navigate to Home page.
- (2) Navigate to My email.
- (3) Navigate to My Account.
- (4) Navigate to Site Map page.
- (5) Navigate to Contact us page.
- (6) Navigate to Members channel.
- (7) Navigate to Services channel.
- (8) Navigate to News & Info channel.
- (9) Navigate to Entertainment channel.
- ([) Skip down to the Primary navigation block.
- (]) Skip down to the more links within this section block.
- (=) Bypass all navigation and jump to the content.
- (x) Text only version of this page.
