when was this type of star discovered?
The modern picture of protostars, summarized above, was first suggested by Chushiro Hayashi in 1966
Protostar
The modern picture of protostars, summarized above, was first suggested by Chushiro Hayashi in 1966
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.
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Protostar [SEP] History
The modern picture of protostars, summarized above, was first suggested by Chushiro Hayashi in 1966. In the first models, the size of protostars was greatly overestimated. Subsequent numerical calculations clarified the issue, and showed that protostars are only modestly larger than main-sequence stars of the same mass. This basic theoretical result has been confirmed by observations, which find that the largest pre-main-sequence stars are also of modest size.