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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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<< < ape hot pho pho Sch > >>

Number of Results: 95 Search : hot
hot pixel
  پیکسل ِ داغ   
piksel-e dâq

Fr.: pixel chaud   

Of a → CCD detector, a pixel that has higher charge loss. Hot pixels are a type of noise affecting almost every CCD camera. They are caused by small contamination or production faults in the CCD sensor area.

hot; → pixel.

hot spot
  لکه‌ی ِ داغ   
lekke-ye dâq (#)

Fr.: point chaud   

A compact, highly luminous region in a cataclysmic binary located in the accretion disk where the stream of material hits it.

hot; → spot.

hot star
  ستاره‌ی ِ داغ   
setâre-ye dâq (#)

Fr.: étoile chaude   

A member of a class of stars having high → effective temperatures (above some 15,000 K); mainly → massive stars, but also including → exciting stars of → planetary nebulae, → white dwarfs, and → symbiotic stars.

hot; → star.

internal photoelectric effect
  اسکر ِ شید-برقی ِ درونی   
oskar-e šid-barqi-ye daruni

Fr.: effet photoélectrique interne   

The → photoelectric effect whereby photons absorbed by a solid (→ semiconductor) raise electrons from a lower to a higher → energy level (from → valence band to → conduction band). See also → external photoelectric effect.

internal; → photoelectric; → effect.

isophotal
  ایزوشیدی   
izošidi

Fr.: isophotal   

Of or relating to → isophotes.

isophote; → -al.

isophotal radius
  شعاع ِ ایزوشیدی   
šo'â'-e izošidi

Fr.: rayon isophotal   

The size attributed to a galaxy corresponding to a particular level of → surface brightness. The reason is that galaxies do not have sharp edges.

isophotal; → radius.

isophote
  ایزوشید   
izošid

Fr.: isophote   

A line joining points with the same surface brightness on a plot or in image of a celestial object such as a nebula or galaxy.

Isophote, from → iso- + a combining form of Gk. phos (gen. photos) "light."

Izošid, from izo-, → iso-, + šid "light, sunlight," from Mid.Pers. šêt "shining, radiant, bright;" Av. xšaēta- "shining, brilliant, splendid, excellent."

Lyman-Werner photon
  فوتون ِ لایمن-ورنر   
foton-e Lyman-Werner

Fr.: photon de Lyman-Werner   

An → ultraviolet photon with an energy between 11.2 and 13.6 eV, corresponding to the energy range in which the Lyman and Werner absorption bands of → molecular hydrogen (H2) are found (→ Lyman band, → Werner band). The first generation of stars produces a background of Lyman-Werner radiation which can → photodissociate molecular hydrogen, the key → cooling agent in metal free gas below 104 K. In doing so, the Lyman-Werner radiation field delays the collapse of gaseous clouds, and thus star formation. After more massive → dark matter clouds are assembled, atomic line cooling becomes effective and H2 can begin to shield itself from Lyman-Werner radiation.

Lyman; → Werner band; → photon.

narrow-band photometry
  شیدسنجی ِ باریک‌باند   
šidsanji-ye bârik bând

Fr.: photométrie à bande étroite   

Photometry using narrow-band filters to isolate a particular spectroscopic line or molecular band.

narrow band; → photometry.

photino
  فوتینو   
fotino (#)

Fr.: photino   

The supersymmetric partner of the → photon.

From phot, from → photon + -ino supersymmetric particle suffix.

photo-
     
šid- (#), nur- (#)

Fr.: photo-   

From Gk. combining form of phos (genitive photos).

Šid- "light, sunlight," from Mid.Pers. šêt "shining, radiant, bright;" Av. xšaēta- "shining, brilliant, splendid, excellent."
Nur-, → light.

photoabsorption
  شید-درشم   
šid-daršam

Fr.: photoabsorption   

A situation in which all of the energy of a photon is transferred to an atom, molecule, or nucleus.

photo- + → absorption.

photocathode
  شید-کاتود، نور-کاتود   
šid-kâtod, nur-kâtod

Fr.: photocathode   

Electrode capable of releasing electrons when illuminated.

photo- + → cathode.

photochemistry
  شید-شیمی، نور-شیمی   
šid-šimi, nur-šimi

Fr.: photochimie   

The study of the chemical and physical changes occurring when a molecule or atom absorbs photons of light.

photo- + → chemistry.

photodesorption
  شید-واشم   
šid-vâšam

Fr.: photodésorption   

Th desorption of surface substances by ultraviolet radiation.

photo-; → desorption.

photodisintegration
  شید-واپاشی، نور-واپاشی   
šidvâpâši, nurvâpâši

Fr.: photodésintégration   

The process by which atomic nuclei are broken apart into their constituent protons and neutrons by the impact of high energy gamma photons. Photodisintegration takes place during the core collapse phase of a → Type II supernova explosion.

photo- + → disintegration.

photodissociate
  شید-واهزیدن   
šid-vâhazidan

Fr.: photodissocier   

To dissociate a → molecule by → radiation. See also → photodissociation.

photo-; → dissociate.

photodissociation
  شید-واهزش، نور-واهزش   
šid-vâhazeš, nur-vâhazeš

Fr.: photodissociation   

The → dissociation of a → chemical compound by → radiation  → energy.

Verbal noun of → photodissociate; → -tion.

photodissociation region (PDR)
  ناحیه‌ی ِ شید-واهزش، ~ نور-واهزش   
nâhiye-ye šid-vâhazeš, ~ nur-vâhazeš

Fr.: région de photodissociation   

A neutral region at the boundary of a → molecular cloud created by the penetration of → far ultraviolet (FUV) radiation from associated stars. The FUV radiation (6 eV ≤ hν ≤ 13.6 eV) dissociates the molecules and heats the gas and dust. A warm, atomic → H I region is thus created and the chemistry and thermal balance of the region are determined by the penetrating FUV photons. The progressive absorption of FUV photons leads to the occurrence of transitions between atomic and molecular phases, such as H I/H2 and C II/C I/CO transitions. By extension, any neutral region where the physics is controlled by FUV photons can be called a PDR, as it is the case for → diffuse interstellar clouds or the edge of → circumstellar disks. The PDR concept was first studied by A. G. G. M. Tielens and D. Hollenbach (1985, ApJ 291, 722).

photodissociation + → region.

photoelectric
  شید-برقی، نور-برقی   
šid-barqi, nur-barqi

Fr.: photoélectrique   

Pertaining to electronic or other electrical effects that are due to the action of electromagnetic radiation, especially visible light.

photo- + → electric.

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