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: 12948 Search : far
blue giant
  غول ِ آبی   
qul-e âbi

Fr.: géante bleue   

A giant star with spectral type O or B.

blue; → giant.

Qul, → giant; âbi, → blue.

blue halo star
  ستارگان ِ آبی ِ هاله   
setâregân-e âbi-ye hâlé

Fr.: étoiles bleues du halo   

A star belonging to a variety of stars located above the → horizontal branch and blueward of the → red giant branch in the → Hertzsprung-Russell diagram of the → halo population.

blue; → halo; → star.

Setâregân plural of setâré, → star, âbi, → blue, hâlé, → halo.

blue HB star
  ستاره‌ی ِ BHB   
setâre-ye BHB

Fr.: étoile BHB   

Same as → blue horizontal branch star.

blue; → horizontal; → branch; → star.

blue hook star
  ستاره‌ی قلاب آبی   
setare-ye qollab-e abi

Fr.: étoile du crochet bleu   

A rare class of → horizontal branch (HB) stars that so far have been found in only very few Galactic → globular clusters. These stars are such called because they form a blue hook at the hot end of the HB in → far ultraviolet (FUV) → color-magnitude diagrams. The physical mechanism that produces blue hook populations is still uncertain. At least two scenarios have been proposed.
In the first scenario these stars are explained as a consequence of extreme → mass loss during the → red giant branch phase and late helium flashing while descending the → white dwarf cooling track. Due to the thin residual hydrogen envelope, helium is mixed into the envelope and hydrogen is mixed into the core during the late → helium flash. As a result, the stars are hotter and UV-fainter than canonical → extreme horizontal branch stars (EHB).
By contrast, in the He self-enrichment scenario the EHB and blue hook stars are produced via the normal evolution of He-enriched sub-populations in globular clusters. These sub-populations might have formed from the ejecta of intermediate-mass → asymptotic giant branch (AGB) stars of the first generation of stars. For the same age and → metallicity, He-enriched HB stars have smaller masses than normal HB stars, resulting in bluer → zero age horizontal branch star (ZAHB) locations. They are also brighter in the FUV, but this effect is reversed for very hot He-enriched HB stars with → effective temperatures larger than 19000 K.
See Dieball A., et al., 2013, arXiv:0901.1309v1, and for blue hook stars in ω Cen cluster, M. Tailo et al., 2015, Nature 523, 318.

blue; → hook; → star.

blue horizontal branch star
  ستاره‌ی ِ آبی ِ شاخه‌ی ِ افقی   
setâre-ye âbi-ye šâxe-ye ofoqi

Fr.: étoile bleue de la branche horizontale   

A member of a population of blue stars appearing on the → horizontal branch in the → Hertzsprung-Russell diagram of the Galactic → halo populations and → globular clusters. Belonging to → spectral types B3 to A0, they have evolved past the → red giant stage and are burning helium in their core.

blue; → horizontal; → branch, → star.

blue jet
  شان ِ آبی   
šân-e âbi

Fr.: jet bleu   

A transient optical phenomenon in the → stratosphere that emerges from the tops of → thunderstorm clouds at tremendous speeds. As their name implies, blue jets are optical ejections from the top of the electrically active core regions of thunderstorms. Following their emergence, they typically propagate upward in narrow cones at vertical speeds of roughly 100 km/s, fanning out and disappearing at heights of about 40-50 km. See also → sprite; → elve.

blue; → jet.

blue leak
  نشت ِ آبی   
našt-e âbi

Fr.: fuite bleue   

Leakage phenomenon in a filter, causing an unwanted response to the blue or green light.

blue; leak, from M.Du. leken "to drip, to leak," or from O.N. leka, cognate of O.E. leccan "to moisten," from P.Gmc. *lek- "deficiency" (cf. O.H.G. lecchen "to become dry," Ger. lechzen "to be parched with thirst").

Našt "leak," origin unknown; âbi, → blue.

blue loop
  گردال ِ آبی   
gerdâl-e âbi

Fr.: boucle bleue   

An evolutionary behavior of certain stars, particularly massive stars, which return to the blue stage after becoming a red supergiant. The phenomenon appears as a blueward loop on the theoretical evolutionary tracks.

blue; → loop.

Gerdâl, → loop, âbi, → blue.

blue Moon
  ماه ِ آبی   
mâh-e âbi

Fr.: lune bleue   

The second full moon in a calendar month. For a blue moon to occur, the first of the full moons must appear at or near the beginning of the month so that the second will fall within the same month. Full moons are separated by 29 days, while most months are 30 or 31 days long; so it is possible to fit two full moons in a single month. This happens every two and a half years, on average.

The folkloric term blue Moon for the calendrical event is new, and apparently goes back to the Maine Farmers' Almanac for 1937. But its original meaning in that work was the third full Moon in a season when there were four full Moons in that season. Some have related the term to the much older English expression moon is blue, which goes back to a couplet from 1528, interpreting it as "something that occurs rarely." However in that poem the expression had a meaning of "something that was absurd." Alternatively, the term blue Moon may have been borrowed from the Chinese lunar calendar particularly in its usage among American Chinese community. In fact in that calendar when there are two full Moons in a month they use the term "blue Moon" and add a thirteenth intercalary month. → blue; → moon.

blue region
  ناحیه‌ی ِ آبی   
nâhiye-ye âbi

Fr.: région bleue   

The portion of the → visible spectrum lying between 455 and 492 nm.

blue; → region.

blue sky
  آسمان ِ آبی   
âsmân-e âbi (#)

Fr.: ciel bleu   

A phenomenon which results from → Rayleigh scattering of sunlight by → atmospheric molecules. → Nitrogen and → oxygen molecules that compose about 78% and 21% of the air, respectively, are small compared to the light → wavelengths, and thus more effective at scattering shorter wavelengths of light (blue and violet). The → selective scattering by these → molecules is responsible for producing the blue skies on a clear sunny day. The sky over the horizon appears much paler in color, because the scattered blue light must pass through more air. Some of it gets scattered away again in other directions. Hence, less blue light reaches the observer's eyes.

blue; → sky.

blue straggler
  ویلان ِ آبی   
veylân-e âbi

Fr.: traînarde bleue, traînard bleu   

Any of stars, often found in → globular clusters and old → open clusters, that lie on the blueward extension of the → main sequence beyond the → turnoff point. Blue stragglers have an anomalously blue color and high luminosity in comparison with other cluster members. The most probable ways in which they could form are: → mass transfer or → coalescence in → close binary systems, encounters or collisions in overcrowded cores of globular clusters.

blue; → straggler.

blue supergiant
  ابرغول ِ آبی   
abarqul-e âbi

Fr.: supergéante bleue   

An evolved star of spectral type O, B, or A; e.g. → Rigel, → Deneb.

blue; → supergiant.

blue wing
  بال ِ آبی   
bâl-e âbi

Fr.: aile bleue   

The → line wing with wavelengths shorter than that of the emission or absorption peak.

blue; → wing.

blueberry
  آبی‌پلار   
âbipelâr

Fr.: myrtille, bleuet   

The edible, usually blueish berry of various shrubs belonging to the genus Vaccinium, of the heath family (TheFreeDictionary).

blue; → berry.

Blueberry galaxy
  کهکشان ِ آبی‌پلار   
kahkešân-e âbipelâr

Fr.: galaxie myrtille, ~ bleuet   

A galaxy having a very small size (< 1 kpc), very low stellar mass (typically 106.5 to 107.5  Msun), very low gas → metallicity (3 to 10% solar → metallicity, and very high → ionization. Blueberry galaxies, compared to star forming → dwarf galaxies, have similar stellar mass and luminosity, but much stronger → [O III] doublet (λλ4959+5007) line strength and gas ionization. Because Blueberry galaxies are selected by the strong [O III] → emission lines, they represent the star-forming → dwarf galaxies with the highest emission line strength and gas ionization. On the other hand, compared to → Green Pea galaxies at → redshifts z ~ 0.2-0.3 and typical high-zLyman alpha emitting galaxies (LAEs) found in the current narrow-band surveys, Blueberry galaxies have similarly strong emission lines but about 10-100 times smaller stellar mass, → star formation rate, and luminosity. So Blueberry galaxies represent the faint-end of → Green Pea galaxies and → Lyman alpha emitting galaxies (Yang et al, 2017, arxiv/1706.02819, and references therein).

blueberry; → galaxy.

blueshift
  آبی-کیب   
âbikib

Fr.: décalage vers le bleu   

The apparent shift of the wavelength towards the shorter wavelength region of the radiation spectrum of an approaching object due to the Doppler effect.

blue; → shift.

blueshifted component
  همنه‌ی ِ آبی-کیب   
hamneye âbikib

Fr.: composante décalée vers le bleu   

A constituent of a composite astronomical object which has a motion directed towards the observer, as revealed by its spectrum.

blueshift; → component.

blur
  ۱) تار کردن، ۲) تار شدن   

Fr.: estomper   

1) (v.tr.) To make indistinct and hazy in outline or appearance.
2) (v.intr.) To become indistinct.

Probably akin to M.E. bleren "to blear."

Târ "dark, obscure, cloudy" Mid.Pers. târ, from Mid./Mod.Pers. târ "dark, obscure, cloudy."

blurred image
  تصویر ِ تار، ~ ِ ناتیگ   
tasvir-e târ, ~ nâtig

Fr.: image estompée, ~ floue   

An image which is dim, indistinct, or vague in appearance, for instance when the optics is not well-focused or when the seeing is poor. The same as → unsharp image, contrary to → sharp image.

Blurred, p.p. of → blur; → image.

<< < -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 cri cro cub cur cyc cyl dar dat daw de- Deb dec dec dee def deg del Den dep der det deu dew dic dif dif dil dip dir dis dis dis dis dis div dog Dop dou dra dua dus dwa dyn e-m ear ecl eco eff ein Ein elb ele ele ele ele Els emi emp ene enr env epi equ equ Eri est Euc eva evo exc exc exh exo exp exp ext ext f-n Fah fam fau fee Fer fib fil fin fir fix fle flu foc for for for fra fre fre fri fun fuz gal gal gal Gan gau GCN gen geo geo geo geo Gl glo gra gra gra gra gra gre gro GW1 hab hal han HAR haz hea hel hel Hen Her heu Hig Hil hol hop hor hou Hub Hum Hyd hyd hyd hyp hys ide ign ima imp imp inc inc ind ine inf inf inf inh INP ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jos Jun K2 Kep key kin Kol lag lam Lan lar las lav lea leg len lev lig lim lin lin lin lis lob loc log lor low lum lun lun Lym Mac mag mag mag mag mag mai Mal mar mas mas mat max mea mea mee Men mer met met met mic mid Mil min Mir mix mod mod mol mon Mor mou mul muo mys nan nat nav nec Nep neu New New NGC nob nom non non nor not nuc nuc num Nyq obj obs obs oce oen OH omn opa ope opt opt opt orb ord Ori ort osc out ove oxy pal pan par Par par par pas pea Pen per per per per per pet pha pho pho pho phy pie Pit Pla pla pla pla ple Poi pol pol pol pol pop pos pos pow pre pre pre Pre pri pri pri pro pro pro pro pro pro Pro pub pul pyr qua qua qua qua Qui rad rad rad rad rad rad ram ran rat rea rec rec rec red ref ref reg reg rel rel rem rep res res res ret rev rho Rie rim riv rol Ros rot rul S a Sah san Sat sca Sch Sch scr sec sec sec sei sel sem sep set sha she sho sid sig sil sim sin sit sky slu sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spl spr sta sta sta sta sta ste ste sti sto str str sub sub sub sug sun sup sup sup sup sur syl syn sys tal Tay tel ten ter tex the the the thi tho thu tid tim tod top tot tra tra tra tra tri tri tro tru tur twi Typ UFO ult unc uni uni uni upg ura uti val var vec vel ver ver vig vir vis voc von wak Was wav wax wea wei whi Wie win WN6 wom X-r yel you zer zod > >>