An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < A s bim col ext gui lat OBN Pop red spi Sta ult wea ZZ > >>

Number of Results: 261 Search : star
late-type star
  ستاره‌ی ِ گونه‌ی ِ فرجامین   
setâre-ye gune-ye farjâmin

Fr.: étoile de type tardif   

A star of → spectral type K, M, S, or C, with a surface temperature lower than that of the Sun. → early-type star. See also → spectral classification.

late; → type; → star.

lithium star
  ستاره‌ی ِ لیتیومی   
setâre-ye litiomi (#)

Fr.: étoile à lithium   

A peculiar evolved star of spectral type G or M whose spectrum displays a high abundance of lithium.

lithium; → star.

low-mass star
  ستاره‌ی ِ کم‌جرم   
setâre-ye kamjerm (#)

Fr.: étoile de faible masse   

A star whose mass is around that of the Sun. See also: → intermediate-mass star; → high-mass star; → star formation.

low; → mass; → star.

M star
  ستاره‌ی ِ M   
setâre-ye M (#)

Fr.: étoile de type M   

A cool, red star of spectral type M with a surface temperatures of less than 3600 K. The spectra of M stars are dominated by molecular bands, especially those of TiO. Naked-eye examples are Betelgeuse and Antares.

M, letter of alphabet, → star.

magnetic massive star
  ستاره‌ی ِ پرجرم ِ مغناتیسی   
setâre-ye porjerm-e meqnâtisi

Fr.: étoile massive magnétique   

A → stellar magnetic field associated with a → massive star. Magnetic fields are detected only for seven to ten percent of all studied massive → OB stars, and the magnetic field occurrence does not depend on the → spectral type. Because these magnetic fields seem to be stable over long time-scales and their strength does not seem to correlate with known stellar properties, it is assumed that they are of fossil origin (→ fossil magnetic field) and are frozen into the → radiative envelope of the stars. The fields are those of the birth → molecular clouds, partly trapped inside the → pre-main sequence star during the cloud → collapse phase, possibly further enhanced by a → dynamo effect in the early fully convective stellar phase. Typically, the polar field strength ranges from about a hundred → Gauss up to several kiloGauss. However, some weaker fields, below 100 G, have recently been detected.
The stellar magnetic field influences many different regions of the star with various effects. In the deep interior of the star, the field influences the internal → mixing of the star and this affects the size of the → convective overshooting region, changing the lifetime of the star by decreasing the amount of fuel for nuclear burning. Magnetic stars can also confine their → stellar winds, due to their strong magnetic fields, into a → magnetosphere, which slows down the → rotational velocity of the star. This → magnetic braking is an efficient mechanism for → angular momentum transport. At the stellar surface, the magnetic fields can create and sustain areas of chemical over- or under-abundances and/or large temperature differences, which are called spots (Buysschaert et al., 2016, astro-ph/1709.02619).

magnetic; → massive; → star.

magnetic star
  ستاره‌ی ِ مغناتیسی   
setâre-ye meqnâtisi (#)

Fr.: étoile magnétique   

A star whose → spectral lines show the → Zeeman effect. See also: → stellar magnetic field, → magnetic massive star, → Ap/Bp star.

magnetic; → star.

Magnetism in Massive Stars (MiMeS)

Fr.: MiMeS   

An international collaboration devoted to the study of the origin and physics of → magnetic fields in → massive stars. The project uses several observatories and a large number of telescopes equipped with → spectropolarimetric and → asteroseismologic instruments, including → HARPS, → HARPSpol, and → ESPaDOnS (Wade et al., 2016, MNRAS 456, 2).

magnetism; → massive; → star.

massive star
  ستاره‌ی ِ پرجرم   
setâre-ye porjerm (#)

Fr.: étoile massive   

A star whose mass is larger than approximately 10 → solar masses. The → spectral types of massive stars range from about B3 (→ B star) to O2 (→ O star) and include → Wolf-Rayet stars as well as → Luminous Blue Variables. Massive stars are very rare; for each star of 20 solar masses there are some 100,000 stars of 1 solar mass. Despite this rarity, they play a key role in astrophysics. They are major sites of → nucleosynthesis beyond oxygen and, therefore, are mainly responsible for the → chemical evolution of galaxies. Due to their high ultraviolet flux and powerful → stellar winds, they bring about interesting phenomena in the → interstellar medium, like → H II regions, → turbulence, → shocks, → bubbles, and so on. Massive stars are progenitors of → supernovae (→ type Ia, → type Ic and → type II), → neutron stars, and → black holes. The formation processes of massive stars is still an unresolved problem. For massive stars the → accretion time scale is larger than the → Kelvin-Helmholtz time scale. This means that massive stars reach the → main sequence while → accretion is still going on.

massive; → star.

morning star
  روجا، ستاره‌ی ِ بامداد   
rujâ (#), setâre-ye bâmdâd (#)

Fr.: étoile du matin   

Not actually a star, but the planet Venus shining brightly in the east just before or at sunrise. Opposed to → evening star.

morning; → star.

Rujâ "morning star" in Tabari, "star" in Gilaki. This word is a variant of official Pers. ruz "day," since in Tabari and Gilaki the phoneme z is sometimes changed into j, as in rujin = rowzan "window" and jir or jer = zir "under." Therefore it is related to rowšan "bright, clear," rowzan "window, aperture;" foruq "light," afruxtan "to light, kindle;" Mid.Pers. rôšn "light; bright, luminous," rôc "day;" O.Pers. raucah-rocânak "window;" O.Pers. raocah- "light, luminous; daylight;" Av. raocana- "bright, shining, radiant;" akin to Skt. rocaná- "bright, shining," roka- "brightness, light;" Gk. leukos "white, clear;" L. lumen (gen. luminis) "light," from lucere "to shine," related to lux "light," lucidus "clear," luna, "moon;" Fr. lumière "light;" O.E. leoht, leht, from W.Gmc. *leukhtam (cf. O.Fris. liacht, M.Du. lucht, Ger. Licht), from PIE *leuk- "light, brightness;" → morning; → star.

multiple star
  ستاره‌ی ِ بستایی   
setâre-ye bastâyi

Fr.: étoile multiple   

A star which appears single but is in fact composed of more than two components. See also → multiple star system; → binary star; → triple star.

multiple; → star.

multiple star system
  راژمان ِ بستایی   
râšmân-e bastâyi

Fr.: système multiple   

A stellar system composed of several stars bound together by gravitational attraction and revolving around a common center of mass.

multiple; → star; → system.

naked-eye star
  ستاره‌ی ِ چشم ِ برهنه   
setâre-ye cašm-e berehné

Fr.: étoile visible à l'œil nu   

A star visible without a telescope. In principle, stars down to about sixth magnitude are visible to the naked eye under ideal conditions, but this depends on the individual, the location, and the conditions of the observation.

naked; → eye; → star.

neutron star
  ستاره‌ی ِ نوترونی، نوترون‌ستاره   
setâre-ye notroni, notron setâré (#)

Fr.: étoile à neutrons   

An extremely compact ball of matter created from the central core of a star that has collapsed under gravity to such an extent that it consists almost entirely of → neutrons. Neutron stars result from two possible evolutionary scenarios: 1) The → collapse of a → massive star during a → supernova explosion; and 2) The accumulation of mass by a → white dwarf in a → binary system. The mass of a neutron star is the same as or larger than the → Chandrasekhar limit (1.4 → solar masses). Neutron stars are only about 10 km across and have a density of 1014 g cm-3, representing the densest objects having a visible surface. The structure of neutron stars consists of a thin outer crust of about 1 km thickness composed of → degenerate electrons and nuclei, which becomes progressively neutron rich with increasing depth and pressure due to → inverse beta decays. In the main body the matter consists of → superfluid neutrons in equilibrium with their decay products, a few percent protons and electrons. Neutron stars have extremely strong magnetic fields, from 3 x 1010 to 1015 gauss. As of 2010 more than 2000 neutron stars have been catalogued, which show a large variety of manifestations, mainly → pulsars.

neutron; → star.

neutron star binary system
  راژمان ِ درین ِ ستاره‌های ِ نوترونی   
râžmân-e dorin-e setârehâ-ye noroni

Fr.: système binaire d'étoiles à neutron   

A → binary system composed of two → neutron stars.

neutron; → star; → binary; → system.

nonrising star
  ستاره‌ی ِ همیشه‌پنهان   
setâre-ye hamiše penhân (#)


A star that is never seen above the horizon from a given position. These stars are located between the celestial pole and a diurnal circle with an angular distance larger than the altitude of the pole.

Nonrising, from → non- + rising adj. of → rise; → star.

Setâré, → star; hamiše penhân, literally "always hidden," coined by Biruni (A.D. 973-1050) in his at-Tafhim, from hamišé "always" (Mid.Pers. hamêšag "always") + penhân "hidden."

nonsetting star
  ستاره‌ی ِ همیشه‌پیدا   
setâre-ye hamiše peydâ (#)


A star that is always seen above the horizon from a given position. These stars are located between the celestial pole and a diurnal circle with an angular distance smaller than the altitude of the pole. Same as → circumpolar star.

Nonsetting, from → non- + setting adj. of → set; → star.

Setâré, → star; hamiše peydâ literally "always visible," coined by Biruni (A.D. 973-1050) in his at-Tafhim, from hamišé "always," → perpetual, + peydâ, → visible.

O star
  ستاره‌ی ِ O   
setâre-ye O (#)

Fr.: étoile de type O   

A luminous, hot, blue star whose spectrum is dominated by the lines of hydrogen, atomic helium, and ionized helium; also known as O-type star. This is the earliest → spectral type and the only → main sequence star in which ionized helium is present. The → effective temperatures of these stars range from about 30,000 K to 50,000 K, their luminosities from 50,000 to 1,000,000 times that of → solar luminosity, and their masses from about 20 to 100 → solar masses. The hottest O-type stars display high ionization emission features such as N III and He II, → Of star. They are divided into subtypes O2, the hottest, to O9.7, the coldest. O-type stars are relatively rare, for each star of 100 solar masses there are 106 stars of solar mass. They are relatively short-lived since they spend only a few million years on the main sequence. The brightest O-type star in the sky visible with naked eye is → Alnitak. For prominent Galactic O stars see → HD 93129.

O, letter of alphabet used in the Harvard spectral classification; → star.

O-type star
  ستاره‌ی ِ گونه‌ی ِ O   
setâre-ye gune-ye O

Fr.: étoile de type O   

Same as → O star.

O, letter of alphabet used in the → Harvard classification; → type; → star.

OB star
  ستاره‌ی ِ OB   
setâre-ye OB

Fr.: étoile OB   

A collective designation for massive O and B stars.

O star; → B star.

OBC star
  ستاره‌ی ِ OBC   
setâre-ye OBC

Fr.: étoile OBC   

A → carbon (C)-rich → O-type or → B-type star.

O star; → B star; → carbon; → star.

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