Protostar

A protostar is a very young star that is still gathering mass from its parent molecular cloud. It is the earliest phase in the process of stellar evolution.^[1] For a low-mass star (i.e. that of the Sun or lower), it lasts about 500,000 years.^[2] The phase begins when a molecular cloud fragment first collapses under the force of self-gravity and an opaque, pressure-supported core forms inside the collapsing fragment. It ends when the infalling gas is depleted, leaving a pre-main-sequence star, which contracts to later become a main-sequence star at the onset of hydrogen fusion producing helium.

^ Stahler, S. W. & Palla, F. (2004). The Formation of Stars. Weinheim: Wiley-VCH. ISBN 3-527-40559-3.
^ Dunham, M. M.; et al. (2014). The Evolution of Protostars in Protostars and Planets VI. University of Arizona Press. arXiv:1401.1809. doi:10.2458/azu_uapress_9780816531240-ch009. ISBN 9780816598762. S2CID 89604015.

[1] Stahler, S. W. & Palla, F. (2004). The Formation of Stars. Weinheim: Wiley-VCH. ISBN 3-527-40559-3.

[2] Dunham, M. M.; et al. (2014). The Evolution of Protostars in Protostars and Planets VI. University of Arizona Press. arXiv:1401.1809. doi:10.2458/azu_uapress_9780816531240-ch009. ISBN 9780816598762. S2CID 89604015.

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