is there anything particular about their evolution?
Star formation begins in relatively small molecular clouds called dense cores.  As the dense core accrues mass from its larger, surrounding cloud, self-gravity begins to overwhelm pressure, and collapse begins.
Protostar
Star formation begins in relatively small molecular clouds called dense cores. Each dense core is initially in balance between self-gravity, which tends to compress the object, and both gas pressure and magnetic pressure, which tend to inflate it. As the dense core accrues mass from its larger, surrounding cloud, self-gravity begins to overwhelm pressure, and collapse begins. 
difference between solar nebula theory and nebular hypothesis The widely accepted modern variant of the nebular theory is the solar nebular disk model (SNDM) or solar nebular model. It offered explanations for a variety of properties of the Solar System what is this hypothesis? The Nebular hypothesis is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System. what does it say about rocky planets? According to the solar nebular disk model, rocky planets form in the inner part of the protoplanetary disk, within the frost line, where the temperature is high enough to prevent condensation of water ice and other substances into grains. does it say anything about protostars? Yes, Gas in the central part of the nebula, with relatively low angular momentum, undergoes fast compression and forms a hot hydrostatic core.  The core gradually grows in mass until it becomes a young hot protostar. when was this type of star discovered? The modern picture of protostars, summarized above, was first suggested by Chushiro Hayashi in 1966
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Protostar [SEP] Protostellar evolution
Star formation begins in relatively small molecular clouds called dense cores. Each dense core is initially in balance between self-gravity, which tends to compress the object, and both gas pressure and magnetic pressure, which tend to inflate it. As the dense core accrues mass from its larger, surrounding cloud, self-gravity begins to overwhelm pressure, and collapse begins. Theoretical modeling of an idealized spherical cloud initially supported only by gas pressure indicates that the collapse process spreads from the inside toward the outside. Spectroscopic observations of dense cores that do not yet contain stars indicate that contraction indeed occurs. So far, however, the predicted outward spread of the collapse region has not been observed.