collective star formation
diseš-e gerdâmdi-ye setâregân
Fr.: formation collective d'étolies
Formation of stars, especially → massive stars, in group as opposed to individual formation.
compact binary star system
râžmân-e dorin-e hampak
Fr.: système binaire compact
A binary star system which is composed of a collapsed object
(→ degenerate dwarf, → neutron star,
or → black hole) in orbit with a low-mass (≤ 0.5 Msol)
secondary star, wherein the collapsed star → accretes
matter from its → companion.
These two objects form a binary system of overall dimensions
106 km with an orbital period of only hours or less.
→ X-ray binary.
compact planetary nebula B[e] star (cPNB[e])
setâre-ye B[e]-ye miq-e sayyâre-yi-ye hampak
Fr.: étoile de nébuleuse planétaire compacte
Fr.: étoile de comparaison
A non-variable star used to monitor the variations of another nearby star.
cosmic star formation peak
cakâd-e keyhâni-ye diseš-e setâregân
Fr.: pic de formation stellaire cosmique
A crucial period in the history of the → Universe, when the bulk of stars in massive galaxies were likely formed. Observations of young stars in distant galaxies at different times in the past have indicated that the → star formation rate peaked at the → redshift of z ~ 2, some 10 billion years ago, before declining by a factor of around ten to its present value (P. Madau & Dickinson, 2014, arXiv:1403.0007).
Fr.: étoile CP
Fr.: étoile noire, ~ sombre
A hypothetical stellar object whose structure or evolution has been affected by → dark matter. Dark matter models predict that in the → early Universe dark matter (in the form of → WIMPs) should congregate and annihilate in the cores of → Population III stars. The result would be dark stars with properties very different from ordinary stars. The reason is that the presence of large amounts of dark matter during the formation of a star inhibits the collapse and can partially prevent further cooling of the gas beyond a certain critical point, well before a → main sequence object has formed. As a consequence, dark matter stars should be more massive, more luminous, and live longer than Pop. III stars, but would be cooler. The formation of dark stars could have had an impact on the → reionization history of the Universe (see, e.g., P. Scott, 2011, astro-ph/1101.1029, and references therein).
setâre-ye gerdé, ~ disk
Fr.: étoile de disque
A star that lies within the → galactic disk of a → spiral galaxy. Stars belonging to the → thin disk, such as the Sun or Alpha Centauri, lie at a typical distance of about 1,000 → light-years from the galactic midplane. There are also → thick disk stars, such as Lalande 21185, that lie at an average distance of about 3,500 light-years from the midplane.
Fr.: étoile donneuse
In a → binary system, a star whose gas is → accreted by a compact companion. The donor may be a → giant or a → supergiant with an enormously distended atmosphere and a significant → stellar wind, or a star filling its → Roche lobe in a → close binary.
setâre-ye dotâyi (#)
Fr.: étoile double
An apparently single star which better observational resolution shows it to be a pair of closely lying stars. They may or may not be physically related.
setâre-ye kutulé (#)
Fr.: étoile naine
A star that burns its hydrogen content to produce its energy and therefore belongs to the main-sequence luminosity class.
early spectral class star
setâré bâ rade-ye binâbi-ye âqâzin
Fr.: étoile de type spectral précoce
setâre-ye gun-ye âqâzin (#)
Fr.: étoile de type précoce
Fr.: étoile EBH
Same as → extreme horizontal branch star.
Fr.: étoile électrofaible
A postulated type of star that could form toward the end of a → massive star's life, after → nuclear fusion has stopped in its → core, and before the star → collapses into a → black hole. In those → extreme conditions, when → temperature and → density inside the star are very high, → quarks could convert into → leptons. Hence huge amounts of energy can be released, much of which would be in the form of → neutrinos.
Fr.: étoile enfouie
A newborn star which is tightly enveloped by a surrounding cloud of gas and dust.
Ebedded p.p. of embed, from en- + bed from O.E. bed "bed," from P.Gmc. *badjam "sleeping place dug in the ground" (O.H.G. betti; Ger. bett); PIE base *bhedh- "to dig, pierce;" cf. Gk. bothyros "pit;" L. fodere "to dig," fossa "ditch;" → star.
Setâré, → star; forupušidé, p.p. of forupušidan, from foru- "below; beneath; down, downwards;" Mid.Pers. frôt "down, downwards;" O.Pers. fravata "forward, downward;" Skt. pravát- "a sloping path, the slope of a mountain" + pušidan "to cover, conceal, clothe; to wear clothes;" Mid.Pers. pôšidan, pôš- "to cover, put on, wear;" cf. Mid.Pers. pôst; Mod.Pers. pust "skin, hide;" O.Pers. pavastā- "thin clay envelope used to protect unbaked clay tablets;" Skt. pavásta- "cover;" Proto-Indo-Iranian *pauastā- "cloth."
setâre-ye šâmgâh (#)
Fr.: étoile du soir
Fr.: étoile évoluée
A star that has left the → main sequence.
Fr.: étoile excitatrice
Fr.: étoile exotique
A hypothetical → compact object composed of particles other than electrons, protons, and neutrons balanced against → gravitational collapse by → degeneracy pressure of corresponding quantum properties.