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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 262 Search : star
guide star
  ستاره‌ی ِ راهبرد   
setâre-ye râhbord

Fr.: étoile de guidage   

A relatively bright star conveniently located in the → field of view used for → guiding.

guide; → star.

He-strong star
  ستاره‌ی ِ هلیوم-سترگ   
setâre-ye heliom-sotorg

Fr.: étoile forte en hélium   

An early → B-type star showing helium lines with abnormally large equivalent widths. The surface → chemical abundances of He-strong stars are influenced by the presence of a strong → magnetic field, resulting in a He overabundance that typically varies in strength over the stellar surface. Examples include HR 735, HD 184927, and CPD-62°2124.

helium; → strong; → line.

He-weak star
  ستاره‌ی ِ هلیوم-نزار   
setâre-ye heliom-nazâr

Fr.: étoile faible en hélium   

A → chemically peculiar star with very weak helium lines. Examples include 3 Sco, HD 176582, HD 217833, HR 2949, and HD 21699. The He-weak stars do not form a homogeneous group. Some of them display intense Si, or Ti and Sr lines, and are considered a hot extension of the magnetic → Ap/Bp stars. Others show overabundances of P and Ga, typically noted for → HgMn stars. The star HD 139160 belongs to the non-magnetic subgroup of He-weak stars.

helium; → weak; → line.

helium star
  ستاره‌ی ِ هلیومی   
setâre-ye heliomi

Fr.: étoile d'hélium   

An → evolved star which has lost most or all of its hydrogen-rich envelope, leaving just a core of helium.

helium; → star.

Herbig AeBe star
  ستاره‌ی ِ هربیگ ِ AeBe   
setâre-ye Herbig-e AeBe (#)

Fr.: étoile de Herbig AeBe   

A young → A-type or → B-type star showing → emission lines in its spectrum. Herbig AeBe stars are → pre-main sequence stars of → intermediate mass (→ intermediate-mass star). They are often called the higher mass counterparts of → T Tauri stars.

Named after George H. Herbig (1920-2013), who first classified them (Herbig 1960, ApJS 4, 337); → A star; → B star; e indicating → emission.

HgMn star
  ستاره‌ی ِ HgMn   
setâre-ye HgMn

Fr.: étoile HgMn   

A → chemically peculiar star of late → B-types. The most distinctive features of HgMn stars are extreme atmospheric overabundance of Hg (up to 5 dex) and of Mn (up to 3 dex). The origin of abundance anomalies observed in late B-type stars with HgMn peculiarity is still poorly understood. More than two thirds of the HgMn stars are known to belong to spectroscopic binaries with a preference of orbital periods ranging from 3 to 20 days (Hurbig et al., 2012, arXiv:1208.2910).

Hg, → mercury; Mn, → manganese; → star. mercury-manganese

high-mass star
  ستاره‌ی ِ مِه‌جرم، ~ پُرجرم   
setâre-ye meh-jerm (#), ~ por-jerm (#)

Fr.: étoile massive   

A star whose mass exceeds 8 solar masses. Same as → massive star. → intermediate-mass star; → low-mass star.

high; → mass; → star.

horizontal branch star
  ستاره‌ی ِ شاخه‌ی ِ افقی   
setâre-ye šâxe-ye ofoqi

Fr.: étoile de la branche horizontale   

A star lying on the → horizontal branch.

horizontal; → branch; → star.

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.

hybrid star
  ستاره‌ی ِ دورگه   
sétâre-ye doragé

Fr.: étoile hybride   

A hypothetical object composed of a → quark matter in the central regions, enveloped by ordinary → hadronic matter.

hybrid; → star.

hypergiant star
  ستاره‌ی ِ هیپرغول   
setâre-ye hiperqul

Fr.: hypergéante   

A high luminosity star with absolute visual magnitude around -10, about 106 times as luminous as the Sun. Hypergiant stars are evolved → massive stars belonging to the luminosity class Ia+ or Ia0. Their spectra show very broadened emission and absorption lines resulting from the high luminosity and low surface gravity which favor strong → stellar wind. See also → Humphreys-Davidson limit; → yellow hypergiant.

hyper-; → giant.

hypervelocity star (HVS)
  ستاره‌ی ِ هیپرتند   
setâre-ye hipertond

Fr.: étoile hypervéloce   

A star whose velocity is so great that it will escape the → gravitational potential of our → Galaxy. Depending on the location and direction of motion, this criterion typically corresponds to a stellar velocity in the Galactic → rest frame larger than 400 km s-1, and up to about 1200 km s-1. The nature of the HVSs spans a wide range of types from → OB stars, to metal-poor → F-type stars and G/K dwarfs. While there is evidence from many late-type B HVSs in the → halo to originate from the Galactic → supermassive black hole (SMBH), other HVSs seem to originate from the → galactic disk. HVSs can obtain their large velocities from a number of different processes:
1) → Tidal disruption of → close binary stars by the central SMBH of the Milky Way. In this process one star is captured by the SMBH while the other is ejected at high speed via the → gravitational slingshot mechanism.
2) Exchange encounters in other dense stellar environments between hard binaries (→ hard binary) and → massive stars may cause stars to be ejected and escape our Galaxy.
3) Disruption of close binaries via → supernova explosions. The → runaway velocities of both ejected stars can reach large values when asymmetric supernovae are considered, i.e. when the newborn → neutron star receives a momentum kick at birth.
(see, e.g., T. M. Tauris, 2014, and references therein, arXiv:1412.0657).

hyper-; → velocity; → star.

intermediate-mass protostar
  پورواستاره‌ی ِ میان‌جرم   
purvâsetâre-ye miyân-jerm

Fr.: protoétoile de masse intermédiare   

A protostar that evolves into an → intermediate-mass star.

intermediate; → mass; → protostar.

intermediate-mass star
  ستاره‌ی ِ میان‌جرم   
setâre-ye miyânjerm

Fr.: étoile de masse intermédiare   

A star whose mass lies in the range about 2 to 8 → solar masses approximately.

intermediate; → mass; → star.

internal structure of stars
  ساختار ِ درونی ِ ستارگان   
sâxtâr-e daruni-ye setâregân (#)

Fr.: structure interne des étoiles   

The physical characteristics of that part of a star lying below the → photosphere. More specifically, the study of its various zones (→ core, → convective zone, → radiative zone) and the transfer of energy through them.

internal; → structure; → star.

isolated massive star formation
  دیسش ِ وایوتیده‌ی ِ ستاره‌ی ِ پرجرم   
diseš-e vâyutide-ye setâre-ye porjerm

Fr.: formation isolée d'étoile massive   

Massive star formation outside → OB associations. Recent observational findings suggest that → massive star formation is a collective process. In other words, massive stars form in → cluster environments and the mass of the most massive star in a cluster is correlated with the mass of the cluster itself. Nevertheless, other observational results give grounds for supposing that massive stars do not necessarily form in clusters but that they can be formed as isolated stars or in very small groups. According to statistical studies nearly 95% of Galactic → O star population is located in clusters or OB associations. This means that a small percentage, about 5%, of high mass stars may form in isolation. Isolation is meant not traceable to an origin in an OB association. This definition therefore excludes → runaway massive stars, which are thought to result from either dynamical interaction in massive dense clusters, or via a kick from a → supernova explosion in a → binary system. Alternatively, isolated massive star has been defined as follows: An O-type star belonging to a cluster whose total mass is < 100 Msun and moreover is devoid of → B stars (Selier et al. 2011, A&A 529, A40 and references therein).

isolated; → massive star; → formation.

isolated neutron star (INS)
  ستاره‌ی ِ نوترونی ِ وایوتیده   
setâre-ye notroni-ye vâyutidé

Fr.: étoile à neutron isolée   

A → neutron star which does not belong to a → binary system, does not have radio emission, and is not surrounded by a progenitor → supernova remnant. INSs appear to be thermally cooling with no emission outside the → soft X-ray band, except for faint optical/UV counterparts. Although these properties are similar to those of → compact central object (CCO)s, they are a distinct class because they lack any observable associated supernova remnant or nebula. There are presently seven confirmed INSs (sometimes referred to as The Magnificent Seven), six of which have measured weakly modulated X-ray pulsations with periods between 3 s and 11 s, much longer than those of CCOs (A. K. Harding, 2013, Front. Phys. 8, 679).

isolated; → neutron; → star.

K star
  ستاره‌ی ِ K   
setâre-ye K (#)

Fr.: étoile de type K   

An orange-red star of → spectral type K with a surface temperature of about 3600-5000 K. The spectra of K stars are dominated by the H and K lines of calcium and lines of neutral iron and titanium, with molecular bands due to cyanogen (CN) and titanium dioxide (TiO). Examples are → Arcturus and → Aldebaran.

K the letter of alphabet; → star.

Kepler's star
  ستاره‌ی ِ کپلر   
setâre-ye Kepler (#)

Fr.: étoile de Kepler   

A → supernova in → Ophiuchus, first observed on 1604 October 9, and described by Johannes Kepler in his book De stella nova (1606). It reached a maximum → apparent magnitude of -3 in late October. The star remained visible for almost a year. The → light curve is that of a → Type Ia supernova. The → supernova remnant consists of a few filaments and brighter knots at a distance of about 30,000 → light-years. It is the radio source 3C 358. Also known as SN 1604 and Kepler's supernova.

Kepler; → star.

Lambda Bootis star
  ستاره‌ی ِ لامبدا گاوران   
setâre-ye lâmbda Gâvrân

Fr.: étoile lambda du Bouvier   

The prototype of a small class of stars (A-F types) which have weak metallic lines (indicating that they are depleted in metals heavier than Si, but with solar abundances of C, N, O, and S). Moreover, they have moderately large rotational velocities and small space velocities. Lambda Boo stars may be pre-main-sequence objects, or they may be main sequence stars that formed from gas whose metal atoms had been absorbed by interstellar dust.

Named after the prototype, the star → Lambda (λ) of constellation → Bootes; → star.

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