Star formation

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. For a low-mass star (i.e. that of the Sun or lower), it lasts about 500,000 years. 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.

dark nebula in the constellation Orion

process by which dense regions within molecular clouds in interstellar space, sometimes referred to as "stellar nurseries" or "star-forming regions", collapse and form stars

contraction of an astronomical object due to the influence of its own gravity

class of eruptive variable star

small patches of nebulosity associated with newly born stars

star in the stage when it has not yet reached the main sequence

mechanism which causes the collapse of interstellar gas clouds and subsequent star formation

young star of spectral types A and B

star in its early stage of evolution

luminosity-temperature relationship obeyed by infant stars

means of comparing the apparent magnitudes of stars at different wavelengths

coherent, wave-shaped gaseous structure in the Milky Way

Astronomical trend of star formation

cold, dense region of a giant molecular cloud