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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 ]
The radiation from the protostar and early star has to be observed in infrared astronomy wavelengths, as the extinction caused by the rest of the cloud in which the star is forming is usually too big to allow us to observe it in the visual part of the spectrum. This presents considerable difficulties as the Earth's atmosphere is almost entirely ...
LRLL 54361 also known as L54361 is thought to be a binary protostar producing strobe-like flashes, located in the constellation Perseus in the star-forming region IC 348 and 950 light-years away. The object may offer insight into a star's early stages of formation, when large masses of gas and dust are falling into a newly forming binary star ...
Protoplanetary disks are thought to be thin structures, with a typical vertical height much smaller than the radius, and a typical mass much smaller than the central young star. [12] The mass of a typical proto-planetary disk is dominated by its gas, however, the presence of dust grains has a major role in its evolution.
Representative lifetimes of stars as a function of their masses The change in size with time of a Sun-like star Artist's depiction of the life cycle of a Sun-like star, starting as a main-sequence star at lower left then expanding through the subgiant and giant phases, until its outer envelope is expelled to form a planetary nebula at upper right Chart of stellar evolution A mass-radius plot ...
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.
The proton–proton chain reaction starts at temperatures about 4 × 10 6 K, [30] making it the dominant fusion mechanism in smaller stars. A self-maintaining CNO chain requires a higher temperature of approximately 1.6 × 10 7 K , but thereafter it increases more rapidly in efficiency as the temperature rises, than does the proton–proton ...
The presence of a magnetic field causes the eventual ejection and collimation of the matter, forming a bipolar outflow or jet. In both cases, bipolar outflows consist largely of molecular gas. They can travel at tens or possibly even hundreds of kilometers per second, and in the case of young stars extend over a parsec in length.