“protostar”的概念、定义、翻译、参考文献-科学参考

protostar

Physics

See stellar evolution.

Astronomy

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. Once it reaches its final mass, it is known as a pre-main-sequence star.

Space Exploration

An early formation of a star that has recently condensed out of an interstellar cloud and which is not yet hot enough for hydrogen burning to start. Protostars derive their energy from gravitational contraction.

Geology and Earth Sciences

Primitive star formed from the break-up 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 10⁷ K hydrogen ‘burning’ begins, marking the transition to a star.

单词	protostar
释义	protostar Physics See stellar evolution. Astronomy 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. Once it reaches its final mass, it is known as a pre-main-sequence star. Space Exploration An early formation of a star that has recently condensed out of an interstellar cloud and which is not yet hot enough for hydrogen burning to start. Protostars derive their energy from gravitational contraction. Geology and Earth Sciences Primitive star formed from the break-up 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 10⁷ K hydrogen ‘burning’ begins, marking the transition to a star.
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