Astronomy: General

A Dictionary of Earth Sciences A Dictionary of Astronomy Further reading

protostar

A Dictionary of Earth Sciences | 1999 | | Copyright

protostar Primitive star formed from the breakup of interstellar clouds. After a fragment becomes detached, it continues to shrink under the influence of its own gravitation, drawing in more gas and dust and increasing in temperature and pressure. Eventually, the outward pressure associated with the rising temperature balances the inward pressure due to gravitation and collapse ceases, perhaps 10 000 years after separation from the cloud. At this stage, the fragment is called a protostar. When internal temperature exceeds 10⁷K hydrogen ‘burning’ begins, marking the transition to a star.

Cite this article
Pick a style below, and copy the text for your bibliography.

MLA
Chicago
APA

AILSA ALLABY and MICHAEL ALLABY. "protostar." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>.

AILSA ALLABY and MICHAEL ALLABY. "protostar." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O13-protostar.html

AILSA ALLABY and MICHAEL ALLABY. "protostar." A Dictionary of Earth Sciences. 1999. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-protostar.html

Learn more about citation styles

protostar

A Dictionary of Astronomy | 1997 | Copyright

protostar A star in the earliest phase of its life, condensing out of a cloud of gas and dust, before the onset of nuclear burning. Its mass grows over about 100 000 years as material falls on to it from the surrounding cloud. A protostar is not visible at optical wavelengths because the infalling material obscures it, but it is bright at infrared wavelengths.

Cite this article
Pick a style below, and copy the text for your bibliography.

MLA
Chicago
APA

"protostar." A Dictionary of Astronomy. 1997. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>.

"protostar." A Dictionary of Astronomy. 1997. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O80-protostar.html

"protostar." A Dictionary of Astronomy. 1997. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O80-protostar.html

Learn more about citation styles

Free newspaper and magazine articles

	Newly-expressed interest delays ProtoStar auction: as satellite operators'... Magazine article from: Television Asia; 11/1/2009
	ProtoStar Ltd selects Space Systems/Loral to deliver satellite.(Brief article) Newspaper article from: Telecomworldwire; 1/8/2007
	Contract awarded to Integral Systems Inc by ProtoStar-II Ltd. Newspaper article from: Telecomworldwire; 4/23/2008