protostar

[proh-toh-stahr]

noun

Astronomy.

1. an early stage in the evolution of a star, after the beginning of the collapse of the gas cloud from which it is formed, but before sufficient contraction has occurred to permit initiation of nuclear reactions at its core.

protostar

/ ˈprəʊtəʊˌstɑː /

noun

1. a cloud of interstellar gas and dust that gradually collapses, forming a hot dense core, and evolves into a star once nuclear fusion can occur in the core

protostar

1. A celestial object made of a contracting cloud of interstellar medium (mostly hydrogen gas) that eventually becomes a main-sequence star. Disturbances in some region of interstellar medium can cause fluctuations of density through that region, and the denser areas, having more mass, begin to attract more and more of the medium through the force of gravity (a process known as accretion). Ever increasing densities of such protostar regions lead to ever higher temperatures within the accreting body, until the point is reached when thermal energy is sufficient to promote the fusion reactions typical of main-sequence stars. Less massive protostars may take hundreds of millions of years to evolve into stars; massive ones contract more quickly and may take only a few hundred thousand years.

Word History and Origins

Origin of protostar¹

First recorded in 1945–50; proto- + star

Example Sentences

There are also always huge jets of gas that get shot out from the protostar, away from the disc.

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"It's all thanks to JWST's exceptional sensitivity combined with high angular resolution that we're able to detect these faint spectral features associated with ices around such a distant protostar," Sewilo said.

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"These structures are perpetually penetrated by magnetic fields, which brings with it magnetic flux. However, if all this magnetic flux were retained as the star developed, it would generate magnetic fields many orders of magnitude stronger than those observed in any known protostar," explains Kazuki Tokuda of Kyushu University's Faculty of Sciences and first author of the study.

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Planets form in disks of dust and gas called protoplanetary disks that whirl around a central protostar during its final assembly.

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As such, the chemicals identified around this protostar were likely present in the first stages of development of our solar system and later delivered to the primitive Earth.

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