An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 500
Betelgeuse (α Orionis)
Ebtoljowzâ (#)

Fr.: Bételgeuse   

The → red supergiant that is the second brightest star in the constellation → Orion. Betelgeuse is one of the biggest stars known with a size of almost 1,000 times larger than the Sun, corresponding to an angular diameter of 43.76 ± 0.12 milli-arcseconds (Perrin et al. 2004, A&A 418, 675). It is a → semiregular variable whose → apparent visual magnitude varies between 0.2 and 1.2 shining very rarely more brightly than its neighbor → Rigel. The energy released by Betelgeuse is estimated to be only 13% in the form of visible light, with most of its radiation being at → infrared wavelengths. The distance of Betelgeuse is 643±146 → light-years (Harper et al. 2008, AJ 135, 1430), while its luminosity is about 140,000 times that of the Sun (→ solar luminosity). Its → spectral type is M2 Iab, its → surface temperature about 3,600 K, and its → initial mass 10 to 20 → solar masses (Msun). Neilson & Lester (2011, arXiv:1109.4562) recently proposed a mass of 11.6 (+5.0, -3.9) Msun for Betelgeuse, while Dolan et al. (2008, BAPS 53, APR.S8.6) obtained about 21 Msun. Its → rotation period is estimated to be about 17 years (Uittenbroek et al. 1998, AJ 116, 2501). Recent observations with the → Very Large Telescope resolve not only the apparent surface of Betelgeuse, but also reveal a large and previously unknown plume of gas extending into space from the surface of the star (Kervella et al. 2009, A&A 504, 115). The plume extends to at least six times the diameter of the star, corresponding to the distance between the Sun and Neptune. This detection suggests that the whole outer shell of Betelgeuse is not shedding matter evenly in all directions. More recently, an image of the surface of the star was obtained using long → baseline → interferometry at infrared wavelengths (Haubois et al. 2009, A&A 508, 923). It shows the presence of an irregular flux distribution possibly caused by enormous → convective cells. A very large dusty envelope has also been observed at larger distances from the star (Kervella et al. 2011, A&A 531, A117).

Betelgeuse, from Ar. Ibt al-Jauza' (ابط‌الجوزاء) "the armpit of Jauza'," from ibt "armpit" + Jauza' "Orion."

Ebtoljowzâ, from Ar. Ibt al-Jauza'.


Fr.: bethe   

A unit of energy equal to 1044 → joules or 1051 → ergs, corresponding to the amount of energy liberated in a typical → supernova explosion. It is used by some theoreticians.

In honor of Hans Bethe (1906-2005), Nobel Prize in Physics (1967), for his work on the theory of stellar nucleosynthesis. The unit name was proposed by Steven Weinberg (1933-) in 2006 for Bethe's contributions to the supernova research aftre 1980.

Bethe ansatz
  آنزاتس ِ بته   
ânzâts-e Bathe

Fr.: ansatz de Bethe   

An → ansatz initially used to deal with → antiferromagnetism in a quantum system. It has been generalized to various quantum → n-body problems.

First introduced by Hans Bethe (1906-2005), → bethe; → ansatz.

BHB star
  ستاره‌ی ِ BHB   
setâre-ye BHB

Fr.: étoile BHB   

Same as → blue horizontal branch star.

blue; → horizontal; → branch; → star.

do- (#)

Fr.: bi-   

Prefix denoting "two, both, twice."

From L. bi-, cognate of Gk. di-, O.E. twi-; cf. Av. bi- "two," biš "twice," Mod.Pers. do "two," PIE *dwo- "two."

Do, Mid.Pers. do, Av. dva-, Skt. dvi-, Gk. duo, L. duo, E. two, Ger. zwei, Fr. deux.

Bianchi cosmological model
  مدل ِ کیهانشناختی ِ بیانکی   
model-e keyhânšenâxti-ye Bianchi

Fr.: modèle cosmologique de Bianchi   

A cosmological model based on the theory of → general relativity, which is homogeneous but → anisotropic. There are actually ten dinstinct Bianchi types, classified according to the particular kinds of symmetry they posses.

Luigi Bianchi (1856-1928), Italian mathematician; → cosmological; → model.

  ۱) ورک؛ ۲) پیش-تنش؛ ۳) ورک دادن   
1) varak; 2) pištaneš; 3) varak dâdan

Fr.: 1, 2) biais; 3) biaiser   

1) General: Leaning of the mind toward or away from something; especially: a personal and sometimes unreasoned judgment.
Statistics: A → systematic error introduced by selecting items from a wrong population, favoring some of the elements of a population, or poorly phrasing questions.
2) Electronics: A → voltage applied to a device to establish a reference level for operation. Same as initial voltage, initial tension (Ger. die Vorspannung). In a → CCD detector, electronic → offset which prevents negative signal.
3a) General: To give a settled and often prejudiced outlook to.
3b) Electronics: To apply a small voltage to a device to control its operation. See also: → bias error, → bias frame, → bias offset, → bias voltage, → biased, → biased estimate, → biased galaxy formation, → biased sample, → biased statistics, → debias, → kinematic bias, → Lutz-Kelker bias, → Malmquist bias, → observational bias, → sampling bias, → unbiased, → unbiased estimator.

From M.Fr. biais "slant," perhaps ultimately from Gk. epikarsios "slanting, oblique," from epi- "upon" + karsios "oblique."

Varak, from var "side, direction" + -ak suffix denoting relation, affinity, similarity (as in dastak, poštak, pašmak, xarak, nâxonak, mušak, eynak). Note also var in yekvar "slanting, inclined".
Pištaneš, only in the electronic sense, from piš, → pre- + taneš, → tension.
Varak dâdan, from varak + dâdan "to give," → datum.

bias error
  ایرنگ ِ ورک، خطای ~   
irang-e varak, xatâ-ye ~

Fr.: erreur de biais   

A measurement error that remains constant in magnitude for all observations; for example an incorrectly set zero adjustment.

bias; → error.

bias frame
  نورداد برای ِ ورک   
nurdâd barây-e varak

Fr.: pose pour biais   

CCD frame with exposure time set to zero and giving the bias level.

bias; → frame.

Nurdâd, → exposure; varakbias

bias offset
  اپنه ِ ورک   
apneh-e varak

Fr.: biais   

In → CCD detectors, same as → bias and → offset.

bias; → offset.

bias voltage
  ولتاژ ِ ورک   
voltâž-e varak

Fr.: voltage de biais   

A voltage applied or developed between two electrodes as a bias.

bias; → voltage.


Fr.: biaisé   

Marked by or exhibiting bias; characterized by settled and often prejudiced outlook.

Biased, from → bias + adj. suffix -ed.

Varakdâr, from varak, → bias + -dâr "possessing, having," from dâštan "to possess, to have."

biased estimate
  بر‌آورد ِ ورکدار   
barâvard-e varakdâr

Fr.: estimation biasiée   

Of a population parameter, if the mean or expectation of the statistics is not equal to the parameter.

biased; → estimate.

barâvard, → estimate; varakdârbiased.

biased galaxy formation
  دیسش ِ ورکدار ِ کهکشانها   
diseš-e varakdâr-e kahkašânhâ

Fr.: formation biaisée de galaxies   

The theory that bright galaxies form preferentially from anomalously overdense perturbations in the → early Universe.

biased; → galaxy; → formation.

biased sample
  نمونان ِ ورکدار   
nemunân-e varakdâr

Fr.: échantillon biaisé   

A sample that is not a true representative of a → statistical population to which generalizations are to be made. A sample which is not → randomly constituted.

biased; → sample.

biased statistics
  آمار ِ ورکدار   
âmâr-e varakdâr

Fr.: statistique biasée   

A statistics based on a → biased sample.

biased; → statistics.

biaxial crystal
  بلور ِ دو‌آسه   
bolur-e doâsé

Fr.: cristal biaxe   

A birefrigent crystal, such as mica, that is characterized by having two optical axes along which light is propagated with equal velocities.

Biaxial, from → bi- "two" + axial, from → axe; → crystal.


Fr.: BICEP2   

A → microwave → polarimeter designed specifically to target the → B-mode signature of → inflation in the → cosmic microwave background polarization. BICEP2 observed from the South Pole for three seasons from 2010 to 2012. This 26 cm aperture → telescope comprised an all-cold refracting optical system equipped with a → bolometer array of 512 → detectors (256 pixels) operating at 150 GHz.

BICEP2, the upgraded version of the first BICEP, short for Background Imaging of Cosmic Extragalactic Polarization.

biconcave lens
  عدسی ِ دوکاو   
adasi-ye dokâv

Fr.: lentille biconcave   

Describing a lens with two concave faces.

bi-; → concave; → lens.

biconvex lens
  عدسی ِ دوکوژ   
adasi-ye dokuž

Fr.: lentille biconvexe   

A → spherical lens with two convex faces. The radii of curvature for the two surfaces may or may not be the same.

bi-; → convex; → lens.

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