1) Pertaining to a class of objects with a mass less than 8 percent that of the Sun.
Fr.: limite sous-stellaire
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.
Fr.: objet sous-stellaire
Fr.: point substellaire
The point on the Earth, or other body, at which a particular star is directly overhead at a given time.
Fr.: nature sous-stellaire
unbound young stellar system (UYSS)
râžmân-e setâre-yi-ye javân-e nâbandidé
Fr.: système stellaire jeune non lié
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).
violent interstellar environment
pargir-e andar-axtari-ye surâ
Fr.: environnement interstellaire violent
A description of the interstellar medium justified by the presence of supersonic shock waves, massive star winds, turbulence, supernova explosions, etc.
young stellar object (YSO)
barâxt-e setâreyi-ye javân
Fr.: objet stellaire jeune
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.