An Etymological Dictionary of Astronomy and Astrophysics
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1) Pertaining to a class of objects with a mass less than 8 percent that of the Sun.
2) → substellar point.

→ sub- + → stellar.

The mass limit below which → hydrogen fusion cannot take place, and the cloud collapse cannot lead to the formation of a star. The limit is 0.075 → solar masses, corresponding to about 80 Jupiter masses.

→ substellar; → limit.

An object with a mass too small to sustain the → proton-proton chain and thus become a true star. See → brown dwarf.

→ substellar; → object.

The point on the Earth, or other body, at which a particular star is directly overhead at a given time.

→ substellar; → point.

The fact or condition, for an object, of not being capable to sustain the → hydrogen fusion because of its low mass (less than 0.08 → solar masses).

→ substellar + → -ity.

A class of gravitationally loose stellar conglomerate with a notable apparent shape making it different from typical → bound  → star clusters. The UYSS class includes a large range of objects, which extend at various size scales and at various degrees of self-binding; from small (semi-)compact → unbound systems named → stellar associations, to huge extended superstructures of → massive stars that make up whole parts of Galactic → spiral arms, known as → stellar complexes (Gouliermis, D. A., 2018, PASP 130:072001; arXiv:1806.11541).

→ unbound; → young; → stellar; → system.

A description of the interstellar medium justified by the presence of supersonic shock waves, massive star winds, turbulence, supernova explosions, etc.

→ violent; → interstellar; → environment.

Any star that has evolved past the → protostar stage, but has not yet arrived on the → main sequence. There is a variety of YSOs depending on their age, mass, and environment, including → Herbig stars, → T Tauri stars, and, in general, compact infrared sources embedded in molecular clouds.

→ young; → stellar; → object.