An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

<< < B r bac Bal Bar bar bea bel Bes bia Big bin bio Bir bla bla blo blu bol Boo bou Bq bre bro bug > >>

Number of Results: 479
Besselian year
  سال ِ بسلی   
sâl-e Beseli

Fr.: année besselienne   

The period taken for the right ascension of the mean Sun to increase by 24 hours. The starting point is when the mean Sun's longitude is 280°, corresponding roughly to January 1. It is virtually the same as the tropical year.

Besselian; → year.

best fit
  بهترین سز   
behtarin saz

Fr.: meilleur ajustement   

In a scatter plot, a mathematical line or curve that passes as near to as many of the data points as possible.

Best, M.E., from O.E. betst, akin toi O.E. bot "remedy." Fit, from M.E. fitten "to marchal troops," from or akin to M.Dutch vitten "to be suitable."

Behtarin supperlative of beh "good, fine" (Mid.Pers. veh "better, good," O.Pers. vahav-, vahu-, Av. vah-, vohu- "good," cf. Skt. vasu- "good," Hittite wasu-, Gaulish vesus "good") + saz, from sazidan "to be fit, proper," from Mid.Pers. saz, sazistan "to be fitting, proper."

Beta Cephei
  بتا-کفیءوس   
betâ Kefeus

Fr.: bêta Céphée   

The second brightest star in the constellation → Cepheus and the prototype of → Beta Cephei variables. It is a variable B2 type → giant star with a visual magnitude of 3.23 varying with a period of 4.57 hours. Its mass is a dozen times that of the Sun. Beta Cephei is a → triple system lying at a distance of about 600 → light-years. The inner → spectroscopic companion, → spectral type A, is only about 45 AU away, and takes around 90 years to orbit. The third visual companion is at least 2400 AU away, with an orbital period of at least 30,000 years.

Beta (β), the second letter of the Gk. alphabet; → Cepheus.

Beta Cephei variable
  ورتنده‌ی ِ بتا-کفؤسی   
vartande-ye betâ Kefeusi

Fr.: variables bêta Céphée   

A variable star, of early B or late O types, undergoing radial pulsations with short periods (< 1 day). Beta Cephei stars are confined within a narrow band of the → H-R diagram above the upper → main sequence. They are believed to be near the end of core hydrogen-burning stars of approximately 10 to 20 solar masses. The famous bright stars → Spica and → Mirzam belong to this family.

Beta Cephei; → variable.

beta decay
  تباهی ِ بتا   
tabâhi-ye betâ (#)

Fr.: désintegration bêta   

The transformation of a → radioactive nuclide in which a → beta particle is emitted. In beta minus decay, a → neutron changes into a → proton, → antineutrino, and → electron: n → p + e + ν-. Beta plus decay involves the conversion of a proton to a neutron, → positron, and → neutrino: p → n + e+ + ν.

Beta (β), from → beta particle; → decay.

beta minus decay
  تباهی ِ بتا کمن   
tabâhi-ye betâ kaman

Fr.: désintegration bêta moins   

beta particle.

beta particle; → minus; → decay.

beta particle
  ذره‌ی ِ بتا   
zarre-ye betâ (#)

Fr.: particule bêta   

An → electron or a → positron emitted from an unstable nucleus during a → radioactive process known as → beta decay.

The term "beta particle" relates to the early history of the → radioactivity studies when the nature of the emergent particles was not elucidated; → particle.

Beta Pictoris (β Pic)
  بتا-نگارگر   
betâ Negârgar

Fr.: bêta Pictoris   

The second brightest star, with an apparent magnitude of 3.86, in the southern constellation → Pictor. Beta Pic is a young star of spectral type A lying 63 → light-years away. It has a luminosity 8.6 times that of the Sun and its surface temperature is 8250 K. Beta Pic is surrounded by a dust and gas disk stretching 400 A.U. away from the star in each direction, 10 times the average distance of Pluto from the Sun. The disk is not symmetric, one side is brighter than the other. Moreover, it has an inner clear zone about the size of our solar system (some 30 A.U.). Recently a probable giant → exoplanet lying in the disk has been imaged.

Beta (β), the second letter of the Gk. alphabet; → Pictor.

beta plus decay
  تباهی ِ بتا بیشن   
tabâhi-ye betâ bišan

Fr.: désintegration bêta plus   

beta particle.

beta particle; → plus; → decay.

beta-meteoroid
  بتا-شخانه‌وار   
β-šaxânevâr

Fr.: β-météoroïde   

A solid object with a mass about 10-18-10-15 kg in → interplanetary space that moves in hyperbolic orbit as a result of the solar → radiation pressure.

meteoroid.

Betelgeuse (α Orionis)
  ابط‌الجوزا   
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'.

bethe
  بته   
bethe

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.

bi-
  دو-   
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.

bias
  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.

<< < B r bac Bal Bar bar bea bel Bes bia Big bin bio Bir bla bla blo blu bol Boo bou Bq bre bro bug > >>