An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



Number of Results: 12 Search : G star
accreting star
  ستاره‌ی ِ فربالنده   
setâre-ye farbâlandé

Fr.: étoile accrétrice, étoile qui accrète   

The star which → accretes matter, particularly in its protostellar phase or in a close binary system.

accreting; → star.

evening star
  ستاره‌ی ِ شامگاه   
setâre-ye šâmgâh (#)

Fr.: étoile du soir   

Any bright → planet, often → Venus, seen low in the western sky after → sunset. → Hesperus.

evening; → star.

exciting star
  ستاره‌ی ِ بر انگیزنده   
setâre-ye barangizandé

Fr.: étoile excitatrice   

A star associated with an interstellar ionized nebula (→ H II region or → planetary nebula) whose energetic → ultraviolet, → photons → ionize the nebula.

Exciting, verbal adj. of → excite; → star.

G star
  ستاره‌ی G   
setâre-ye G

Fr.: étoile G   

A member of a class of stars to which the Sun belongs. The G-type stars on the → main sequence have → surface temperatures of 5,300-6,000 K and therefore appear yellow in color. G type → giant stars (such as → Capella) are almost 100-500 K colder than the corresponding main sequence stars. G type → supergiants have temperatures of 4,500-5,500 K. The spectrum of early type G stars, such as the Sun (G2), is dominated by ionized lines of calcium (→ H and K lines, mainly) and neutral metals. In later type G stars the molecular bands of → CH molecules and → CN molecules become visible. The main sequence and giant stars have masses of ~ 1 solar mass, while the supergiants are of ~ 10 solar masses. The luminosities of G-type giants are almost 30-60 times greater than that of the Sun, whereas the supergiants are 10,000-30,000 times more luminous.

G, from the → Harvard classification; → star.

morning star
  روجا، ستاره‌ی ِ بامداد   
rujâ (#), setâre-ye bâmdâd (#)

Fr.: étoile du matin   

Not actually a star, but the planet Venus shining brightly in the east just before or at sunrise. Opposed to → evening star.

morning; → star.

Rujâ "morning star" in Tabari, "star" in Gilaki. This word is a variant of official Pers. ruz "day," since in Tabari and Gilaki the phoneme z is sometimes changed into j, as in rujin = rowzan "window" and jir or jer = zir "under." Therefore it is related to rowšan "bright, clear," rowzan "window, aperture;" foruq "light," afruxtan "to light, kindle;" Mid.Pers. rôšn "light; bright, luminous," rôc "day;" O.Pers. raucah-rocânak "window;" O.Pers. raocah- "light, luminous; daylight;" Av. raocana- "bright, shining, radiant;" akin to Skt. rocaná- "bright, shining," roka- "brightness, light;" Gk. leukos "white, clear;" L. lumen (gen. luminis) "light," from lucere "to shine," related to lux "light," lucidus "clear," luna, "moon;" Fr. lumière "light;" O.E. leoht, leht, from W.Gmc. *leukhtam (cf. O.Fris. liacht, M.Du. lucht, Ger. Licht), from PIE *leuk- "light, brightness;" → morning; → star.

nonrising star
  ستاره‌ی ِ همیشه‌پنهان   
setâre-ye hamiše penhân (#)


A star that is never seen above the horizon from a given position. These stars are located between the celestial pole and a diurnal circle with an angular distance larger than the altitude of the pole.

Nonrising, from → non- + rising adj. of → rise; → star.

Setâré, → star; hamiše penhân, literally "always hidden," coined by Biruni (A.D. 973-1050) in his at-Tafhim, from hamišé "always" (Mid.Pers. hamêšag "always") + penhân "hidden."

nonsetting star
  ستاره‌ی ِ همیشه‌پیدا   
setâre-ye hamiše peydâ (#)


A star that is always seen above the horizon from a given position. These stars are located between the celestial pole and a diurnal circle with an angular distance smaller than the altitude of the pole. Same as → circumpolar star.

Nonsetting, from → non- + setting adj. of → set; → star.

Setâré, → star; hamiše peydâ literally "always visible," coined by Biruni (A.D. 973-1050) in his at-Tafhim, from hamišé "always," → perpetual, + peydâ, → visible.

Piazzi's Flying Star
  ستاره‌ی ِ پرنده‌ی ِ پیاتزی   
setâre-ye parande-ye Piazzi

Fr.: étoile volante de Piazzi   

Same as → 61 Cygni and → Bessel's star.

Giuseppe Piazzi (1746-1826) was the first to notice the large → proper motion of the star, in 1804. His observations over a period of 10 years revealed the largest proper motion ever detected for any star at the time, leading him to baptize it the "Flying Star;" → fly; → star.

pulsating star
  ستاره‌ی ِ تپنده   
setâre-ye tapandé (#)

Fr.: étoile pulsante   

A type of → variable star that changes its brightness by changing its volume through expansion and contraction. Classical pulsating stars, including → Cepheids, → RR Lyrae, and → Delta Scuti variables, are located in a quite narrow almost vertical region in the → H-R diagram, known as → instability strip. See also → kappa mechanism.

Pulsating, verbal adj. of → pulsate; → star.

rotating star
  ستاره‌ی ِ چرخان، ~ چرخنده   
setâre-ye carxân, ~ carxandé

Fr.: étoile en rotation   

A star that has a non-zero → angular velocity. In a rotating star, the → centrifugal forces reduce the → effective gravity according to the latitude and also introduce deviations from sphericity. In a rotating star, the equations of stellar structure need to be modified. The usual spherical coordinates must be replaced by new coordinates characterizing the → equipotentials. See also → von Zeipel theorem.

rotating; → star.

shooting star
šahâb (#)

Fr.: étoile filante   

Colloquial name for → meteor.

Shooting, from shoot (v.); M.E. shoten; O.E. sceotan "to shoot" (cf. O.N. skjota, Du. schieten, Ger. schießen), from PIE base *skeud- "to shoot, to chase, to throw;" → star.

Šahâb, → meteor.

stochastic self-propagating star formation
  دیسش ِ ستارگان با خود-توچش ِ کاتورگین   
diseš-e setâregân bâ xod-tuceš-e kâturgin

Fr.: formation d'étoiles par auto-propagation stochastique   

A mechanism that could be responsible for global → spiral structure in galaxies either by itself or in conjunction with spiral → density waves. In this mechanism, star formation is caused by → supernova-induced → shocks which compress the → interstellar medium. The → massive stars thus formed may, when they explode, induce further → star formation. If conditions are right, the process becomes self-propagating, resulting in agglomerations of young stars and hot gas which are stretched into spiral shaped features by → differential rotation. Merging of small agglomerations into larger ones may then produce large-scale spiral structure over the entire galaxy. The SSPSF model, first suggested by Mueller & Arnett (1976) was developed by Gerola & Seiden (1978). While the → density wave theory postulates that spiral structure is due to a global property of the galaxy, the SSPSF model examines the alternative viewpoint, namely that spiral structure may be induced by more local processes. The two mechanisms are not necessarily mutually exclusive, but they involve very different approaches to the modeling of galaxy evolution. The SSPSF gives a better fit than the density wave theory to the patchy spiral arms found in many spiral galaxies. However, it cannot explain → galactic bars.

stochastic; → self; → propagate; → star; → formation.