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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 ]
A more compact site of star formation is the opaque clouds of dense gas and dust known as Bok globules, so named after the astronomer Bart Bok. These can form in association with collapsing molecular clouds or possibly independently. [13] The Bok globules are typically up to a light-year across and contain a few solar masses. [14]
The collapse releases gravitational energy, which heats up the protostar. This process occurs on the free fall timescale, which is roughly 100,000 years for solar-mass protostars, and ends when the protostar reaches approximately 4000 K. This is known as the Hayashi boundary, and at this point, the protostar is on the Hayashi track.
Massive galactic molecular outflows may have the physical conditions such as high gas densities to form stars. This star-formation mode could contribute to the morphological evolution of galaxies. [7] Infrared image of a bipolar outflow. The outflow is driven by a massive young star that was first identified as a radio source and catalogued "DR ...
A star forms by accumulation of material that falls in to a protostar from a circumstellar disk or envelope. Material in the disk is cooler than the surface of the protostar, so it radiates at longer wavelengths of light producing excess infrared emission. As material in the disk is depleted, the infrared excess decreases.
A pre-main-sequence star (also known as a PMS star and PMS object) is a star in the stage when it has not yet reached the main sequence.Earlier in its life, the object is a protostar that grows by acquiring mass from its surrounding envelope of interstellar dust and gas.
In astronomy, the initial mass function (IMF) is an empirical function that describes the initial distribution of masses for a population of stars during star formation. [1] IMF not only describes the formation and evolution of individual stars, it also serves as an important link that describes the formation and evolution of galaxies. [1]
Based on recent computer model studies, the complex organic molecules necessary for life may have formed in the protoplanetary disk of dust grains surrounding the Sun before the formation of the Earth. [20] According to the computer studies, this same process may also occur around other stars that acquire planets. [20]