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
pre-stellar core
  مغزه‌ی ِ پیش-ستاره‌ای   
maqze-ye piš-setâreyi

Fr.: cœur pré-stellaire   

A small, gravitationally unstable molecular → clump of typical size of less than 0.1 pc resulting from → gravitational collapse and → fragmentation of a larger → molecular cloud. It is a centrally concentrated structure which evolves into a → class 0 object, where eventually a single star or a stellar system is formed. Core masses range between 0.5 and 5 solar masses, with a mean number density of at least 104-105 cm-3, and a temperature as low as about 10 K. A pre-stellar core evolves into a → Class 0 object. Also called dense core.

pre-stellar; → core.


Fr.: protostellaire   

Of or pertaining to → protostars.

proto-; → stellar.

protostellar collapse
  ر ُمبش ِ پوروا-ستاره‌ای   
rombeš-e purvâ-setâreyi

Fr.: effondrement protostellaire   

A → gravitational collapse leading to the formation of a → protostar.

protostellar; → collapse.

protostellar disk
  گرده‌ی ِ پوروا-ستاره‌ای   
gerde-ye purvâ-setâreyi

Fr.: disque protostellaire   

A disk of gas and dust surrounding a → protostar. These structures are rotating → accretion disks through which matter is transferred to protostars.

protostellar; → disk.

protostellar jet
  شان ِ پورواستاره‌ای   
šÃ¢n-e purvâsetâre-yi

Fr.: jet protostellaire   

A high-velocity and highly → collimated jet associated with the earliest phase of → star formation that propagating along the polar axis of the → protostar-→ accretion disk system. Protostellar jets are usually detected in the [S II], [O I], and Hα lines and are therefore referred to as optical jets. They may have more than a parsec in length. Their formation is related to the → magnetohydrodynamics (MHD) of accretion disks. These jets are detected in protostellar sources over a wide range of masses, from the very early stages of formation (sources associated with infalling envelopes whose mass exceeds that of the growing star) all the way to the → classical T Tauri stars, whose envelopes have already dispersed. This phenomenon is thought to play a key role in regulating the star formation process by removing the excess → angular momentum of disk material and enabling matter to flow toward the center. Protostellar winds also provide an important → feedback mechanism between the forming star and the surrounding medium, to which they return mass and energy. Protostellar jets are at the origin of → bipolar outflows. The et sweeps up ambient → molecular cloud material into two thin shells, which manifest themselves as the observed bipolar lobes of → carbon monoxide (CO) emission. Once the molecular cloud material has been swept away (on a timescale of 105 years), the bipolar outflow disappears, leaving the protostellar jet to erratically fire away for a further 106-107 years.

protostellar; → jet.

quasi-stellar object
  بر‌آخت ِ چونان‌ستاره‌ای   
barâxt-e cunân-setâre-yi

Fr.: objet quasi-stellaire   

Initial name of → quasars.

quasi-; → stellar; → object.

quasi-stellar radio source
  ر‌آدیو-خن ِ چونان‌ستاره، ~ ~ ِ ستاره‌وش   
râdio-xan-e cunân setâré, ~ ~ setâré-vaš

Fr.: radiosource quasi-stellaire   

A quasar with detectable radio emission.

quasi-; → stellar; → radio; → source.

stellar aberration
  بیراهش ِ ستاره‌ای   
birâheš-e setâre-yi

Fr.: aberration stellaire   

Same as → aberration of starlight .

stellar; → aberratio.

stellar association
  آهزش ِ ستاره‌ای   
âhazeš-e setâre-yi

Fr.: association stellaire   

1) A large, loose grouping of 10 to 1000 stars that are of similar spectral type and share a common origin. The members move together through space, but have become gravitationally → unbound. Stellar associations are primarily identified by their common movement vectors and ages. → OB association; → T association; → R association.
2) An → unbound stellar agglomeration for which the age of the stars is smaller than the → crossing time (Giels & Portegies Zwart, 2010, MNRAS Letters, astro-ph/1010.1720). See also → star cluster.

The concept of stellar association was first introduced by Viktor A. Ambartsumian (1908-1996), Armenian astrophysicist (1947, Stellar Evolution and Astrophysics, Armenian Acad. of Sci.; German translation, Abhandl. Sowjetischen Astron. Ser. 1. 33, 1951). → stellar; → association.

stellar astronomy
  اخترشناسی ِ ستاره‌ای   
axtaršenâsi-ye setâreyi (#)

Fr.: astronomie stellaire   

The branch of astronomy that deals with the study of stars, their physical properties, formation, and evolution. Same as → stellar astrophysics and → stellar physics.

stellar; → astronomy.

stellar astrophysics
  اخترفیزیک ِ ستاره‌ای   
axtarfizik-e setâre-yi

Fr.: astrophysique stellaire   

The field of → astrophysics concerned with the study of the physical characteristics of stars, more specifically their → internal structure, physical processes taking place in their interiors, atmospheres, → stellar winds, → mass loss, interaction with the → interstellar medium, as well as the physical laws governing → star formation. Same as → stellar physics and → stellar astronomy.

stellar; → astrophysics.

stellar atmosphere
  جوّ ِ ستاره‌ای، هواسپهر ِ ~   
javv-e setâre-yi, havâsephre ~

Fr.: atmosphère stellaire   

The outer envelope of gas and plasma that surrounds a star; characterized by pressure, temperature, density, chemical composition, and opacity at varying altitudes.

stellar; → atmosphere.

stellar atmosphere model
  مدل ِ جو ِ ستاره   
model-e javv-e setâré

Fr.: modèle d'atmosphère stellaire   

A model that computes the radiation field crossing the boundary layers of a star at all frequencies. The parameters used for the characterization of a stellar atmosphere model are: → effective temperature, → surface gravity, and → metallicity.

stellar; → atmosphere; → model.

stellar bar
  میله‌ی ِ ستاره‌ای   
mile-ye setâre-yi

Fr.: barre stellaire   

A bar-shaped accumulation of stars in galaxies, created by → density waves in a → spiral galaxy. → galactic bar, → barred spiral galaxy.

stellar; → bar.

stellar black hole
  سیه‌چال ِ ستاره‌ای   
siyah câl-e setâre-yi

Fr.: trou noir stellaire   

A → black hole with a mass in the range 3-30 → solar masses representing the end-product of → massive star evolution. Since → neutron stars cannot have masses larger than 3 solar masses, compact objects more massive than this must be black holes. There is good observational evidence for the existence of stellar black holes, based in particular on dynamical measurements of the masses of compact objects in → transient X-ray sources. Same as → stellar-mass black hole.

stellar; → black; → hole.

stellar complex
  همتافت ِ ستاره‌ای   
hamtâft-e setâre-yi

Fr.: complexe stellaire   

Any of the largest stellar assemblages consisting of the groupings of → star clusters, → stellar associations, and individual stars with sizes of 300-1000 → parsecs and ages of up to 100 millions years. Most stellar complexes are physical entities containing objects of common origin and are the birth places of most star clusters and associations. The brightest and youngest complexes are well-known stellar superstructures that outline the Galactic → spiral arms, and also include → H II regions, → giant molecular clouds, and → neutral hydrogen clouds (Efremov, Y. N., 1996, The Origins, Evolutions, and Densities of Binary Stars in Clusters, ASP Conf. Series, Vol. 90).

stellar; → complex.

stellar creation function
  کریای ِ آفرینش ِ ستارگان   
karyâ-ye âfarineš-e setâregân

Fr.: fonction de création stellaire   

The number of stars born per unit area in the mass range log M to log M + d log M during the time interval t to t + dt. The integration of the creation function over time gives the → present-day mass function (Miller & Scalo, 1797, ApJSS 41, 513).

stellar; → creation; → function.

stellar cusp
  تیزه‌ی ِ ستاره‌ای   
tize-ye setâre-yi

Fr.: cuspide stellaire   

A steeply rising radial profile (→ cusp) in the number density of stars in the central region of a galaxy resulting from the gravitational influence of a central → supermassive black hole, as predicted by theoretical models. An important assumption of all cusp formation models is that the stellar cluster is in dynamical equilibrium in the black hole potential. This radial profile is usually characterized by a power law of the form n(r) ∝ r, with a slope that is steeper than that of a flat isothermal → core. For a single-mass stellar cluster, Bahcall & Wolf (1976) determined the dynamically relaxed cusp will have γ = 7/4. The presence of such a cusp is important observationally because it may represent a simple test for black holes in stellar systems where dynamical mass estimates are difficult, such as in the cores of galaxies. In the case of the Milky Way, several attempts have been done to probe the presence of such a stellar cusp. However, the presence of the cusp is not confirmed. For example, based on the late-type stars alone, Do et al. (2009, ApJ 703, 1323), show that γ is less than 1.0 at the 99.7% confidence level. This is consistent with the nuclear star cluster having no cusp, with a → core profile that is significantly flatter than that predicted by most cusp formation theories, and even allows for the presence of a central hole in the stellar distribution (See also Genzel et al., 2010, Rev.Mod.Phys. 82, 3121, also at astro-ph/1006.0064).

stellar; → cusp.

stellar dynamics
  توانیک ِ ستاره‌ای   
tavânik-e setâre-yi

Fr.: dynamique stellaire   

The field of astrophysics that describes systems of many → point mass particles whose mutual gravitational interactions determine their orbits. Theses systems include → star clusters, → globular clusters, and galaxies (→ galaxy) consisting of about 102-103, 104-106, and up to about 1012 members respectively. Stellar dynamics deals with systems in which each member contributes importantly to the overall gravitational field and is usually concerned with the statistical properties of many orbits. It can be compared to the → kinetic theory of gases developed in the late 19th century. In contrast, → celestial mechanics deals with systems where the gravitational force of a massive planet or star determines the orbits of its satellites.

stellar; → dynamics.

stellar evolution
  فرگشت ِ ستاره   
fargašt-e setâré

Fr.: évolution stellaire   

The gradual changes in physical state (spectrum, luminosity, temperature) and chemical composition that occurs during the life of a star.

stellar; → evolution.

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