young stellar object

American  

noun

plural

young stellar objects

1. Astronomy. a developing star that is further along its evolution than a protostar, but has not yet reached the main sequence.

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young stellar object Scientific  

1. A protostar in which the dust and gas have collapsed into a sufficiently massive body for fusion to begin. The characteristic trait of young stellar objects is the presence of jet outflows—either of molecular gas or of radioactive emissions—that interact with the interstellar medium out of which the star has just been born.

2. See more at protostar

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