Star formation

Star formation is the process by which gas in molecular clouds gets transformed into stars.

Related Topics:
Molecular cloud - Star

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In the current paradigm of star formation, cores of molecular clouds (regions of especially high density) become gravitationally unstable, fragment and begin to collapse (sometimes, shockwaves from supernovae will trigger star formation in nearby gas clouds). Part of the gravitational energy lost in this collapse is radiated in the infrared, with the remainder increasing the temperature of the core of the object. The accretion of material happens partially through a circumstellar disc. When the density and temperature are high enough, deuterium fusion ignition occurs, and the outward pressure of the resultant radiation slows (but does not stop) the collapse. Material from the cloud continues to "rain" onto the protostar. In this stage bipolar flows are produced, probably an effect of the angular momentum of the infalling material. Finally, hydrogen begins to fuse in the core of the star, and the rest of the enveloping material is cleared away.

Related Topics:
Collapse - Supernova - Infrared - Circumstellar disc - Deuterium - Fusion - Protostar - Angular momentum - Hydrogen

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The stages of the process are well defined in stars with masses around one solar mass or less. In high mass stars, the length of the star formation process is comparable to the other timescales of their evolution, much shorter, and the process is not so well defined.

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The later evolution of stars are studied in stellar evolution.

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