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 : stellar
interstellar extinction
  خاموشی ِ اندر-اختری   
xâmuši-ye andaraxtari

Fr.: extinction interstellaire   

The dimming of light traveling in the interstellar space due to the combined effects of absorption and scattering by interstellar dust particles. Interstellar extinction increases at shorter (bluer) wavelengths, resulting in → interstellar reddening.

interstellar; → extinction.

interstellar gas
  گاز ِ اندر-اختری   
gâz-e andaraxtari

Fr.: gaz interstellaire   

Gas, mostly hydrogen, in the interstellar space found in a variety of forms: molecular, atomic, ionized, plasma.

interstellar; → gas.

interstellar grain
  دانه‌ی ِ اندر-اختری   
dâne-ye andaraxtari

Fr.: grain interstellaire   

Irregularly shaped → dust grains that occur in the → interstellar medium. They are mostly composed of carbon and/or silicates and measure a fraction of micron across.

interstellar; → grains.

interstellar line
  خطّ ِ اندر-اختری   
xatt-e andaraxtari

Fr.: raie interstellaire   

A spectral line formed in the interstellar medium, in particular an absorption line which does not participate in the periodic Doppler shift of intrinsic absorption lines in a binary star.

interstellar; → line.

interstellar magnetic field
  میدان ِ مغناتیسی ِ اندر-اختری   
meydân-e meqnâtisi-ye andaraxtari

Fr.: champ magnétique interstellaire   

A large-scale, weak magnetic field, with an estimated strength of about 1 to 5 microgauss, that pervades the disk of the Milky Way Galaxy and controls the alignment of interstellar dust grains.

interstellar; → magnetic; → field.

interstellar maser
  میزر ِ اندر-اختری   
meyzer-e andaraxtari

Fr.: maser interstellaire   

A maser phenomenon created by young stars and → protostars in the surrounding dense → molecular clouds of gas and dust. See also → circumstellar maser; → ammonia maser; → methanol maser; → OH maser; → water maser.

interstellar; → maser.

interstellar matter
  مادّه‌ی ِ اندر-اختری   
mâdde-ye andaraxtari

Fr.: matière interstellaire   

The gas and dust that exists in open space between the stars. See also → interstellar medium.

interstellar; → matter.

interstellar medium (ISM)
  مدیم ِ اندر-اختری   
madim-e andaraxtari

Fr.: milieu interstellaire   

The environment containing the → interstellar matter, consisting of gas (mostly hydrogen) and dust. Even at its densest phase, the interstellar medium is emptier than the best vacuum man can create in the laboratory, but because space is so vast, the interstellar medium still adds up to a huge amount of mass.

interstellar; → medium.

interstellar molecule
  مولکول ِ اندر-اختری   
molekul-e andaraxtari

Fr.: molécule interstellaire   

Any molecule that occurs naturally in clouds of gas and dust in the interstellar medium. So far more than 140 species have been discovered, many of which nonexistent on Earth.

interstellar; → molecule.

interstellar object (ISO)
  بر‌آخت ِ اندر‌اختری   
barâxt-e andaraxtari

Fr.: objet interstellaire   

A body other than a → star or → substellar object located in → interstellar space and not → gravitationally bound to a star. Its → hyperbolic orbit would indicate an object not bound to the Sun. The first known ISO is → 1I/'Oumuamua. ISOs are icy → planetesimals that are expected to behave like the → long-period comets of the solar system; volatile ices sublimate when the ISO approaches the Sun, developing a → coma and a → dust tail -- features that should make them bright and therefore easy to spot. The rocky ISOs, on the other hand, only reflect sunlight. As their → albedo is expected to be extremely low they become dark (after eons of bombardment by high-energy cosmic rays), they would be extremely faint and hard to detect (Hainaut et al., 2018, The Messenger 173, 13).

interstellar; → object.

interstellar polarization
  قطبش ِ اندر-اختری   
qotbeš-e andaraxtari

Fr.: polarisation interstellaire   

The polarization of starlight caused by aligned → interstellar grains, so that initially → unpolarized light from a star is partially polarized by the time it reaches the Earth.

interstellar; → polarization.

interstellar radiation field
  میدان ِ تابش ِ اندر-اختری   
meydân-e tâbeš andaraxtari

Fr.: champ de rayonnement interstellaire   

A global ionizing radiation in the → interstellar medium provided by various sources all together.

interstellar; → radiation; → field.

interstellar reddening
  سُرخش ِ اندر-اختری   
sorxeš-e andaraxtari

Fr.: rougissement interstellaire   

The dimming of light during its travel in the → interstellar medium due to absorption by → intervening → dust grains. Since shorter wavelengths are particularly affected, the spectrum of the light is increasingly dominated by the long wavelength end of the spectrum. As a result, the light is "reddened" as it travels through space. Robert J. Trumpler (1886-1956), a Swiss-American astronomer, was the first to produce a definite evidence of the existence of → interstellar extinction and to estimate its magnitude (1930).

interstellar; → reddening.

interstellar reddening curve
  خم ِ سُرخش ِ اندر-اختری   
xam-e sorxeš-e andaraxtari

Fr.: courbe de rougissement interstellaire   

A graph showing the relation between → interstellar absorption (in magnitudes) and wavelength.

interstellar; → reddening; → curve.

interstellar scintillation
  سوسوی ِ اندر-اختری   
susu-ye andaraxtari

Fr.: scintillation interstellaire   

An apparent twinkling of the signals from distant point-like radio sources (pulsars). It is due to turbulence, i.e. fluctuations in the electron density of the interstellar ionized gas, through which the signals have passed on their way to Earth.

interstellar; → scintillation.

local interstellar cloud
  ابر ِ اندر-اختری ِ محلی   
abr-e andar-axtari-ye mahali

Fr.: nuage interstellaire local   

An → interstellar cloud that surrounds the → heliosphere.

local; → interstellar; → cloud.

minimum stellar mass
  جرم ِ کمینه‌ی ِ ستاره   
jerm-e kamine-ye setâre

Fr.: masse stellaire minimum   

The amount of hydrogen necessary to form a star; more specifically the minimum mass to ignite → hydrogen fusion. → Hydrogen burning will start at a limit of about 0.08 Msun, or 75 → Jupiter masses. Below 0.08 Msun, the core never gets hot enough to trigger → hydrogen fusion. → Protostars less massive than this limit are known as → brown dwarfs or → planets if the mass is less than 13 Jupiter masses. Above 13 Jupiter masses, some minor nuclear reactions (→ deuterium burning) occur that do not provide much energy. The minimum mass for → star formation is a critical parameter with profound astrophysical, cosmological, and even anthropic consequences.

minimum; → stellar; → mass.

Modules for Experiments in Stellar Astrophysics (MESA)

Fr.: MESA   

An open-source, one-dimensional astrophysical code which is capable of calculating the evolution of stars in a wide range of environments. It works according to the → Henyey method and uses many modules that deal with various aspects of the theoretical models, such as the → equation of state (EOS), → nuclear reaction networks, → chemical composition, micro-physics, or macro-physics. The EOS and corresponding opacities or nuclear networks are provided in tabulated formats and can be selected by the user, while the micro-physics and macro-physics can be controlled by inlists of relevant parameters and settings (Paxton et al. 2015, ApJS 220, 15 and references therein).

module; → experiment; → stellar; → astrophysics.

old stellar population
  پرینش ِ ستاره‌ای ِ کهن   
porineš-e setâre-yi-ye kohan

Fr.: population stellaire vielle   

A population of stars in a stellar system that have definitely left the → main sequence.

old; → stellar; → population.


Fr.: pré-stellaire   

An adjective relating to a stage before the formation of a → protostar. → pre-stellar core.

pre-; → stellar.

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