An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < 25 cou eru gro Lan pai Rus sup sup sup sup tid upp > >>

Number of Results: 254 Search : up
upper level
  تراز ِ بالا، ~ زبرین   
tarâz-e bâlâ (#), ~ zabarin (#)

Fr.: niveau supérieur   

In atomic physics, an initial energy state in an emission transition.

upper; → level.

upper limit
  حدِ بالا، ~ زبرین   
hadd-e bâlâ (#), ~ zabarin (#)

Fr.: limite supérieure   

Of an integral operator, the point at which the integration ends.

upper; → limit.

upper main sequence
  رشته‌ی ِ فریست ِ زبرین   
rešte-ye farist-e zabarin

Fr.: séquence principale supérieure   

A → main sequence star with a mass above 1.5 Msun. Upper main sequence stars have high central temperatures so that they produce their energy through the → CNO cycle. The outward energy flux is very high and therefore this flux cannot be maintained by → radiative transfer. Thus, upper main sequence stars have → convective cores. Outside the core, there is a → radiative zone. The mass of the convective core gradually diminishes as the hydrogen is consumed. The surface hydrogen is fully ionized and the → opacity is due to → electron scattering The opacity due to electron scattering.

upper; → main; → sequence.

upper mantle
  گوشته‌ی ِ زبرین   
gušte-ye zabarin

Fr.: manteau supérieur   

The upper part of the Earth's → mantle which begins at the base of the → crust around 35 km and extends downward to about 410 km.

upper; → mantle.

upper mass cut-off
  بره‌ی ِ بالایی ِ جرم، ~ زبرین ِ ~   
bore-ye bâlâyi-ye jerm, ~ zabarin-e ~

Fr.: coupure aux masses élevées   

Same as → upper mass limit.

upper; → mass; → cut-off.

upper mass limit
  حد ِ بالایی ِ جرم، ~ زبرین ِ ~   
hadd-e bâlâyi-ye jerm, ~ zabarin-e ~

Fr.: limite supérieure de masses   

The highest mass range admitted in a star formation model. The high mass end of the → initial mass function. The upper mass limit is a critical parameter in understanding → stellar populations, → star formation, and → massive star feedback in galaxies.

upper; → mass; → limit.

upper transit
  گذر ِ زبرین   
gozar-e zabarin (#)

Fr.: passage supérieur   

The movement of a celestial body across a celestial meridian's upper branch. Same as → upper culmination.

upper; → transit.

farâzâb (#)

Fr.: en amont   

1) Toward or in the higher part of a stream; against the current. → downstream
2) Directed upstream; situated upstream.

up; → stream.

Farâz, → height; water, → water.

Vela supernova remnant
  بازمانده‌ی ِ اَبَر-نو‌اَختر ِ بادبان   
bâzmânde-ye abar-now-axtar-e Bâdbân

Fr.: reste de supernova du Voile   

A → supernova remnant located in the southern Milky Way in the constellation → Vela. It has a large angular diameter of about 8° and lies 250 ± 30 pc away (Cha et al. 1999, ApJ 515, L25). Its overall emission is dominated by the interaction of the → supernova blast wave with the → interstellar medium. This SNR is also notable for a number of protrusions extending well beyond its rim, which were suggested to be fragments of ejecta from the supernova explosion. X-ray spectroscopy has since confirmed several of these protrusions to indeed be strongly enriched with ejecta. The age of the SNR is estimated to be ~11,000 years, based on the spin-down rate of the associated → Vela pulsar, but ages as large as 20,000-30,000 years have also been argued.

Vela; → supernova remnant.

Virgo supercluster
  اَبَر-خوشه‌ی ِ دوشیزه   
abar-xuše-ye Dušizé

Fr.: superamas de la Vierge   

The irregular supercluster that contains the Virgo cluster and the Local Group. At least 100 galaxy groups and clusters are located within its diameter of 110 million light-years. It is one of millions of superclusters in the observable Universe.

Virgo; → supercluster.

volcanic eruption
  اسدرش ِ آتشفشانی   
osdareš-e âtašfešâni

Fr.: éruption volcanique   

The explosive ejection of superheated matter from a → volcano.

volcanic; → eruption.

working group
kâr-goruh (#)

Fr.: groupe de travail   

A group of people working together to achieve a stated goal.

work; → -ing; → group.

yellow supergiant (YSG)
  اَبَر-غول ِ زرد   
abarqul-e zard (#)

Fr.: supergéante jaune   

A supergiant star of type F and G whose effective temperature is between 4800 and 7500 K. Yellow supergiants are extremely rare, because they represent a very short-lived phase, typically a few tens of thousands of year, in the evolution of → massive stars.

yellow; → supergiant.

zero suppression
  نهاوش ِ صفر   
nehâveš-e sefr

Fr.: suppression de zéro   

The removal of non-significant zeroes from a number. For example, replacing 531.2300 by 531.23.

zero; → suppression.

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