An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 88 Search : ray
gamma-ray astronomy
  اخترشناسی ِ پرتوها‌ی ِ گاما   
axtaršenâsi-ye partowhâ-ye gâmmâ (#)

Fr.: astronomie en rayons gamma   

The study of → gamma rays from → extraterrestrial → sources, especially → gamma-ray bursts.

gamma ray; → astronomy.

gamma-ray burst (GRB)
  بلک ِ پرتوها‌ی ِ گاما   
belk-e partowhâ-ye gâmmâ

Fr.: sursaut de rayons gamma   

An intense discharge of → gamma rays, which range in duration from tenth of a second to tens of seconds and occur from sources widely distributed over the sky. The radio wave → afterglow from the → burst can last more than a year, making long-term observations of the sources possible. The favored hypothesis is that they are produced by a relativistic jet created by the merger of two → compact objects (specifically two → neutron stars or a neutron star and a → black hole). Mergers of this kind are also expected to create significant quantities of neutron-rich radioactive species, whose decay should result in a faint → transient, known as a → kilonova, in the days following the burst. Indeed, it is speculated that this mechanism may be the predominant source of stable → r-process elements in the Universe. Recent calculations suggest that much of the kilonova energy should appear in the → near-infrared spectral range, because of the high optical opacity created by these heavy r-process elements (Tanvir et al., 2017, Nature 500, 547).

gamma rays; → burst.

gamma-ray burster
  بلک‌گر ِ پرتو ِ گاما   
belkvar-e partow-e gâmmâ

Fr.: source à sursaut gamma   

The → object or → phenomenon at the origin of a → gamma-ray burst.

gamma ray; → burster.

gamma-ray source
  خن ِ پرتوهای ِ گاما   
xan-e partowhâ-ye gâmma

Fr.: source de rayons gamma   

1) An astronomical object that emits → gamma rays.
2) A radioactive material that emits gamma rays in a form that can be used in medical imaging.

gamma ray; → source.

GCN: The Gamma-ray Coordinates Network
  توربست ِ هماراهای ِ پرتوهای ِ گاما   
turbast-e hamârâhâ-ye partowhâ-ye gâmâ

Fr.: Le réseau des coordonnées des rayons gamma   

A follow-up community network concerned with → gamma-ray burst (GRB)s. It deals with: 1) locations of GRBs and other → transients detected by spacecraft (most in real-time while the GRB is still bursting), and 2) reports of follow-up observations (the Circulars) made by ground-based and space-based optical, radio, X-ray, TeV, and other observers. The GCN Circulars allow the GRB follow-up community to make optimum use of its limited resources (labor and telescope time) by communicating what has already been done or will soon be done.

gamma ray; → coordinate; → network.

xâkestari (#)

Fr.: gris   

(n.) A color between white and black. (adj.) Having a neutral hue.

M.E., O.E. græg, from P.Gmc. *græwyaz; cf. O.N. grar, O.Fris. gre, Du. graw, Ger. grau; Frank. *gris, Fr. gris.

Xâkestari, "ash-colored," from xâkestar "ashes," from Mid.Pers. *xâkâtur, from xâk "earth, dust" + âtur "fire," varaint âtaxš (Mod.Pers. âtaš, âzar, taš), from Av. ātar-, āθr- "fire," singular nominative ātarš-; O.Pers. ātar- "fire;" Av. āθaurvan- "fire priest;" Skt. átharvan- "fire priest;" cf. L. ater "black" ("blackened by fire"); Arm. airem "burns;" Serb. vatra "fire;" PIE base *āter- "fire."

gray (Gy)

Fr.: gray   

An SI unit of absorbed radiation dose. One gray is equivalent to an energy absorption of 1 → joule/kg. It has replaced the → rad (rd), an older standard. One gray is equivalent to 100 rad.

Named for Louis Harold Gray (1905-1965), British radiologist and the pioneer of use of radiation in cancer treatment.

gray atmosphere
  جّو ِ خاکستری، هواسپهر ِ ~   
javv-e xâkestari, havâsepher-e ~

Fr.: atmosphère grise   

A simplifying assumption in the models of stellar atmosphere, according to which the absorption coefficient has the same value at all wavelengths.

gray; → atmosphere.

gray body
  جسم ِ خاکستری   
jesm-e xâkestari (#)

Fr.: corps gris   

A hypothetical body which emits radiation at each wavelength in a constant ratio, less than unity, to that emitted by a black body at the same temperature.

gray; → body.

hard X-rays
  پرتوهای ِ X ِ سخت   
partowhâ-ye X-e saxt (#)

Fr.: rayons X durs   

The short wavelength, high energy end of the electromagnetic spectrum. Hard X-rays are typically those with energies greater than around 10 keV. The dividing line between hard and soft X-rays is not well defined and can depend on the context.

hard; → X-rays.

high-energy cosmic rays
  پرتوهای ِ کیهانی ِ مه‌کاروژ، ~ ~ پرکاروژ   
partowhâ-ye keyhâni-ye meh-kâruž, ~ ~ por-kâruž

Fr.: rayons cosmiques de hautes énergies   

Cosmic rays which typically have energies in the range 1015 to 1020 electron volts. For the most part, they are protons and other atomic nuclei, and come from distant cosmos, perhaps even from outside our own Galaxy.

high; → energy; → cosmic; → ray.

high-mass X-ray binary (HMXB)
  درین ِ پرتو ایکس ِ پرجرم   
dorin-e partow-e iks-e por-jerm

Fr.: binaire X de forte masse   

A member of one of the two main classes of → X-ray binary systems where one of the components is a neutron star or a black hole and the other one a → massive star. HMXBs emit relatively → hard X-rays and usually show regular pulsations, no X-ray bursts, and often X-ray eclipses. Their X-ray luminosity is much larger than their optical luminosity. In our Galaxy HMXBs are found predominantly in the → spiral arms and within the → Galactic disk in young → stellar populations less than 107 years old. One of the most famous HMXB is Cygnus X-1 which was the first stellar-mass black hole discovered. See also: → low-mass X-ray binary.

high; → mass; → X-ray; → binary.

incident ray
  پرتو ِ فتان   
partov-e fotân

Fr.: rayon incident   

The → light ray that strikes a surface before → reflection, → refraction, or → absorption. Opposite of → emergent ray.

incident; → ray.

infrared array
  آرست ِ فروسرخ   
ârast-e forusorx

Fr.: détecteur mosaïque infrarouge   

A two-dimensional infrared imaging device, consisting of an array of small, individual electronic detectors, each of which records a pixel in the image.

infrared; → array.

interferometric array
  آرست ِ اندرزنش‌سنجی، ~ اندرزنش‌سنجیک   
ârast-e andarzanešsanji, ~ andarzanešsanjik

Fr.: réseau interférométrique   

A system of several telescopes coupled together in a particular configuration to carry out → interferometry.

interferometric; → array.

ion rays
  پرتوهای ِ یونی   
partowhâ-ye yoni (#)

Fr.: rayons ioniques   

The thin glowing streamers in a comet's ion tail.

ion; → ray.

light ray
  پرتو ِ نور   
partow-e nur

Fr.: rayon de lumière   

An imaginary line directed along the path that the light follows. In other words, light pictured simply in terms of straight lines.

light; → ray.

low-mass X-ray binary (LMXB)
  درین ِ پرتو ایکس ِ کم‌جرم   
dorin-e partow-e iks-e kam-jerm

Fr.: binaire X de faible masse   

A member of one of the two main classes of → X-ray binary systems where one of the components is a → neutron star or → black hole and the other component a → low-mass star with a spectral type A or later. LMXBs mainly emit → soft X-rays. The ratio of their optical to X-ray luminosities is less than 0.1. They belong to → old stellar populations with ages 5-15 × 109 years and are found in → globular clusters and in the → bulge of our → Milky Way galaxy; some are also found in the disk. Hercules X-1 is an example of LMXBs.
See also: → high-mass X-ray binary.

low; → mass; → X-ray; → binary.

ordinary ray
  پرتوِ شونیک   
partov-e šunik

Fr.: rayon ordinaire   

The ray that has an → isotropic speed in a → doubly refracting crystal. It obeys → Snell's law upon refraction at the crystal surface. See also → extraordinary ray

ordinary; → ray.

paraxial ray
  پرتو ِ پر‌آسه‌ای   
partow-e parâse-yi

Fr.: rayon paraxial   

A ray that lies close to and almost parallel to the optical axis and behaves according to paraxial equations.

paraxial, → ray.

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