An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 12942 Search : far
red clump star
  ستاره‌ی ِ گوده‌ی ِ سرخ   
setâre-ye gude-ye sorx

Fr.: étoile du grumeau rouge   

A star on the → horizontal branch which results from the evolution of a → red giant with an initial mass of ~ 1 Msun.

red; → clump; → star.

red dwarf
  کوتوله‌ی ِ سرخ   
kutule-ye sorx (#)

Fr.: naine rouge   

A small, cool, very faint, main sequence star whose surface temperature is under about 3500 K. Red dwarfs generally have masses of less than one-third that of the Sun. In the neighbourhood of the Sun the majority of stars are red dwarfs.

red; → dwarf.

red giant
  غول ِ سرخ، غولپیکر ِ ~   
qul-e sorx (#), qulpeykar-e ~ (#)

Fr.: géante rouge   

A certain star of spectral type K or later that occupies the upper right portion of the → H-R diagram. Red giants are evolved stars that have exhausted their hydrogen fuel in the core. They may have a → luminosity up to 1000 times greater than → main sequence stars of the same → spectral type. Red giants belong to the → luminosity class III or II (bright giants). They are luminous because of their great size, but have a relatively low surface temperature. All normal stars are expected to pass eventually through a red-giant phase as a consequence of stellar evolution. When a main sequence star has converted approximately 10% of its hydrogen to helium, nuclear reactions in the core stop (→ Schönberg-Chandrasekhar limit). The → hydrostatic equilibrium is no longer maintained, and the core contracts while the outer layers expand and cool. This process produces the low surface temperature and large size (from 10 to 100 times that of the Sun) that characterize the red giant. In the core the temperature continues to rise. When it approaches 100,000,000 K helium will begin to fuse into carbon. → helium flash. Prominent bright red giants in the night sky include → Aldebaran and → Arcturus.

red; → giant.

red giant branch (RGB)
  شاخه‌ی ِ غولان ِ سرخ   
šâxe-ye qulân-e sorx

Fr.: branche des géantes rouges   

The evolutionary path of a star that has exhausted its available hydrogen content in the core, between the → main-sequence turnoff and the → helium flash.

red giant; → branch.

red HB star
  ستاره‌ی ِ BHR   
setâre-ye RHB

Fr.: étoile RHB   

Same as → red horizontal branch star.

red; → horizontal; → branch; → star.

red horizontal branch star
  ستاره‌ی ِ سرخ ِ شاخه‌ی ِ افقی   
setâre-ye sorx-e šâxe-ye ofoqi

Fr.: étoile rouge de la branche horizontale   

A star found on the red part of the → horizontal branch. According to theoretical models, these stars result from the evolution of stars with a mass around 0.8 Msun, higher than that giving rise to → BHB stars. Upon helium burning in their cores, the remnant envelope of the red giant collapses.

red; → horizontal; → branch; → star.

red leak
  نشت ِ سرخ   
našt-e sorx

Fr.: fuite rouge   

Unwanted secondary window in a filter band pass, on the red side of the main window.

red; leak, from M.E leken, from O.N. leka "to drip, leak;" akin to Du. lek, Ger. lech "leaky," O.E. leccan "to moisten."

Našt "leak, leakage," of unknown origin; sorx, → red.

Red Spot
  لکه‌ی ِ سرخ   
lakke-ye sorx (#)

Fr.: Tache rouge   

See → Great Red Spot, on Jupiter.

red; → spot.

red supergiant
  ابَرغول ِ سرخ   
abarqul-e sorx (#)

Fr.: supergéante rouge   

A supergiant star with spectral type K or M. Red supergiants are the largest stars in the Universe, but not necessarily the most massive. Betelgeuse and Antares are the best known examples of a red supergiant.

red; → supergiant.

red transient
  گذرای ِ سرخ   
gozarâ-ye sorx

Fr.: transitoire rouge   

A member of a class of exploding stars that are more luminous than → novae but not as luminous as → supernovae. Moreover, their outburst → light curves have multiple peaks. One of the most characteristic features of red transients is that after exploding they cool down to → late-type → M star and develop circumstellar material rich in molecules and dust. Some of the members of the red transients in our Galaxy are V838V, OGLE-2002-BLG-360, V4332 Sgr, and V1309 Sco.

red; → transient.

red wing
  بال ِ سرخ   
bâl-e sorx

Fr.: aile rouge   

Of a spectral line profile, the → line wing with wavelengths longer than that of the emission or absorption peak.

red; → wing.

red-edge
  لبه‌ی ِ سرخ   
labe-ye soex

Fr.: bord rouge   

A rise in a planet's surface → reflectivity between red → absorbance and → near-infrared reflection due to → vegetation. The red-edge is one of the possible signs of life on distant → habitable  → exoplanets. Its presence is attributed to the chlorophyll molecule and leaf structure. The leaves of land plants reflect sunlight much more efficiently long-ward of this edge than they do in the visible. Although the red-edge position for Earth's vegetation is fixed at around 700-760 nm, that for exoplanets may not necessarily be the same (Takizawa et al., 2017, Nature Scientific Reports 7, Article number: 7561).

red; → edge.

redden
  ۱) سُرخیدن؛ ۲) سرخاندن   
1) sorxidan; 2) sorxândan

Fr.: 1) rougir; 2) faire rougir   

1) (v.intr.) Of a spectral line, to reduce in intensity due to absorption by interstellar dust grains.
2) (v.tr.) Of interstellar dust, to absorb the light that passes through it.

Infinitives from → red.

reddened star
  ستاره‌ی ِ سرخیده   
setâre-ye sorxidé

Fr.: étoile rougie   

A star whose light has undergone → reddening.

Reddened, p.p. of → redden; → star.

reddening
  سُرخش   
sorxeš

Fr.: rougissement   

The process by which light from an astronomical object grows red as it travels through interstellar dust. Dust scatters blue light more than red, thus leaving predominantly red light transmitted.

Verbal noun of → redden.

reddening coefficient
  همگر ِ سرخش   
hamgar-e sorxeš

Fr.: coefficient de rougissement   

A dimensionless quantity determined from the comparison of the observed → Balmer decrements with respect to the theoretical values for given physical conditions of electron temperature and density. The reddening coefficient at Hβ is defined as c(Hβ) = log (I(Hβ)/F(Hβ)), where I(Hβ) and F(Hβ) are → de-reddened and reddened fluxes respectively. Also called logarithmic extinction.

reddening; → coefficient.

reddening function
  کریای ِ سرخش   
karyâ-ye sorxeš

Fr.: fonction de rougissement   

The normalized interstellar extinction at a given wavelength. It is defined by f(λ) = A(λ)/A(Hβ) - 1, where A(λ) is the extinction at the given wavelength and A(Hβ) the extinction at Hβ, with f(Hβ) = 0. It is used to → de-redden observed fluxes: I(λ)/I(Hβ) = F(λ)/F(Hβ).10c(Hβ).f(λ), where I represents the flux in the absence of extinction and F the observed flux affected by extinction, c(Hβ) being the → reddening coefficient.

reddening; → function.

reddening parameter
  پارامون ِ سرخش   
pârâmun-e sorxeš

Fr.: paramètre de rougissement   

A dimensionless quantity characterizing the → interstellar extinction, defined by the total-to-selective extinction ratio: RV = AV/E(B-V). The typical value found for the reddening parameter in the Milky Way is RV ~ 3.1, but it is known to vary from one line of sight to another, from values as 2 to as large as 6. Very large → dust grains would produce extinction with RV → ∞.

reddening; → parameter.

reddening vector
  بُردار ِ سرخش   
bordâr-e sorxeš

Fr.: vecteur de rougissement   

A vector indicating the direction in which interstellar reddening moves the position of a star in a multi-dimensional space of color indices.

reddening; → vector.

redshift
  سرخ‌کیب   
sorxkib

Fr.: décalage vers le rouge   

A shift in the lines of an object's spectrum toward longer wavelengths. Redshift indicates that an object is moving away from the observer. The larger the redshift, the faster the object is moving. Redshift is expressed by z = Δλ/λ = v/c, where λ is the wavelength, Δλ the wavelength shift, v the velocity of the source relative to the observer, and c the → speed of light. When v approaches c, redshift is expressed by the → relativistic formula z = ((1 +v/c)/(1 - v/c))½ - 1.

red; → shift.

<< < -es -iv -ti 21- A r abe abs abs acc acc acc act act ada adi adu aff age alc Alf ali all alp alt ama amp ana ang ang ann ano ant ant ape apo app aps arc Arg ari art ass ast ast ast atm ato att aur aut axi B r bac Bal Bar Bar Bay bec Ber Bet Bie bij bin bio bis bla bla blu blu bol Bor bou Bra bre bro Bug C-s cal Cam can car Car Cas cat cav cel cen cer Cha cha cha che cho cir cir cir cla clo clo clu coa coe coh col col col com com com com com com com com com con con con con con con con con con con con coo cor Cor cor cos cos cos Cou cou cra cre cro cru cub cur cyc Cyn dar dat day de- dec dec dec def def deg del den dep Des det deu dex die dif dif dil dip dir dis dis dis dis dis div dom Dor dou Dra duc dus dwa dyn e-t ear ecl eco eff Ein Ein ele ele ele ele ele elv emi emp ene enr epa epo equ equ Err Eta Eul eva evo exc exc exh exo exp exp ext ext Fab fai fan fau fel fer fic fil fin fir fla fli flu foc for for for fra fre fre fro fun fuz Gal gal gal Gar gau geg gen geo geo geo ger gla gly gra gra gra gra gra Gre gro GYR Had Hal hap Har HD hea hel hel hep Her hex hig Him hol hor hos hov Hub Hun hyd hyd hyd hyp IC ide ill Ima imp imp inc inc ind ine inf inf inf ini inp ins ins int int int int Int int int int inv ion Iri irr iso iso ite jel Jou JUp Kan Kep Kil kin Kra Lag Lam Lan Lar las law lea Leg Leo lev lig lim lin lin lin lit loc loc log Lor low lum lun lun Lym Mac mag mag mag mag mag mai Mal mar mas mas mat max mea mec meg men mer met met Met mic mid Mil min Mir mix mod mod mol mon mor mov mul mur n-b nan nat nea neg Ner neu new New NGC noc nom non non nor nou nuc nuc num O-p obl obs obs oce Of? ohm omn opa Oph opt opt or orb ord Ori ort osc out ove ozo pal pan par par par par pat pec pen per per per per per Pfu pha pho pho pho phy pie pla Pla pla pla pla plu poi pol pol pol pol por pos pot pow pre pre pre pre pri pri pri pro pro pro pro Pro pro Prz pul pum Pyx qua qua qua qua R A rad rad rad rad rad rad Ram Ran rat rea rea rec rec red red ref ref reg rei rel rel rem rep res res res ret rev rhy rif Rin rob Rom rot rot rum S s Sak San sav sca Sch Sch scr sec sec SED sei sel sem seq sex Sha she sho sid sig sil sim sin siz sla Sma SNR Sof sol sol sol sol sou sou spa spe spe spe spe sph spi spo squ sta sta sta sta ste ste ste sto sto str str sub sub sub sum sup sup sup sup sur sus sym syn syz tan tea tem ten ter the the the the thi thr tid til tip tom tor tou tra tra tra tra Tri tri tru tsu tur two Typ ult umb unc uni uni unk upp urg uvb val var Veg vel ver vib vio vir vis Voi vow wan wat wav WC wea wel whi Wil wir WNh wor X-r Yer Z s zer [C > >>