setâre-ye gune-ye A
Fr.: étoile de type A
Same as → A star.
A, letter of alphabet used in the → Harvard classification; → type; → star.
Fr.: variables de type Algol
The same as eclipsing binary stars, the prototype of which is Algol.
The original pattern or model from which all things of the same kind are copied or on which they are based; a model or first form; prototype (Dictionary.com).
sayyârak-e gune-ye B
Fr.: astéroïde de type B
A division of → C-type asteroids whose members have relatively low albedos (0.04 to 0.08) and the → ultraviolet absorption below 0.5 μm is small or absent. Examples include → 2 Pallas, 379 Huenna (diameter 62 km), and → 101955 Bennu.
setâre-ye gune-ye B
Fr.: étoile de type B
Same as → B star.
B, letter of alphabet used in the → Harvard classification; → type; → star.
sayârak-e gune-ye C
Fr.: astéroïde de type C
An → asteroid that belongs to the family of → carbonaceous asteroids. They are → depleted in → hydrogen and → helium, have chemical ratios akin to solar composition, and show low → albedo (0.03-0.09). C-type asteroids are the most common variety, forming around 75% of known asteroids. They inhabit → main belt's outer regions.
C stands for → carbonaceous; → type; → asteroid.
D-type ionization front
pišân-e yoneš-e gune-ye D
Fr.: front d'ionisation de type D
An → ionization front of → H II regions whose expansion speed is comparable to the → sound speed in the gas (~ 10 km/sec for hydrogen at 104 K). A D-type ionization front results from → R-type ionization front when its propagation speed decreases as the volume of gas ahead of the ionization front grows. If front velocity is equal to a lower limit (C12 / 2C2, where C1 and C2 are the sound speed ahead and behind the front respectively), the front is called D critical.
D referring to a dense gas; → type; → ionization; → front.
kondrit-e gune-ye E
Fr.: chondrite de type E
Same as → enstatite chondrite.
early-type galaxy (ETG)
kahkešân-e gune-ye âqâzin
Fr.: galaxie de type précoce
In the → Hubble classification, galaxies on the left part of the → Hubble sequence. Early-type galaxies tend to have redder colors, higher average surface brightnesses, and lower → neutral hydrogen content than → late-type galaxies. This terminology is based on the obsolete and erroneous idea that → elliptical and → lenticular galaxies might be evolutionary precursors to → spiral and → barred spiral galaxies.
setâre-ye gun-ye âqâzin (#)
Fr.: étoile de type précoce
Hot, luminous stars of → spectral type O, B, A, and F0 to F5. They were originally thought, wrongly, to be at an earlier stage of evolution than → late-type stars. See also → spectral classification.
setâre-ye gune-ye F
Fr.: étoile de type F
A star whose spectrum is characterized by strong → absorption lines of ionized → calcium, Ca II (→ H and K lines), which become much stronger than the hydrogen lines of the → Balmer series. A multitude of fainter metallic lines are also present. Ca II lines strengthen to later types. → Main sequence F stars, of which → Procyon is an example, have a → surface temperature of 6,000 to 7,400°C and a mass of 1.1 to 1.4 → solar masses (Habets & Heintze, 1981, AASS 46, 193).
B, letter of alphabet used in the → → Harvard classification; → type; → star.
G type star
setâre-ye gune-ye G
Fr.: étoile de type G
A yellowish star whose surface temperature is about 6000 K and its spectrum is dominated by H and K lines of ionized calcium (Ca II 3968 Å and 3934 Å).
G from the alphabetical sequence of spectral types; → type; → star.
sayyârak-e gune-ye G
Fr.: astéroïde de type G
A relatively uncommon → carbonaceous carbonaceous asteroid whose spectrum contains a strong → ultraviolet → absorption feature below 0.5 μm (→ Tholen classification). In the → SMASS classification it corresponds to the Cg and Chg types , depending on the presence or absence (respectively) of the absorption feature at 0.7 μm. The most remarkable "asteroid" in this type is → Ceres (now classified as a → dwarf planet).
setâre-ye gune-ye G
Fr.: étoile de type G
Same as → G star.
late-type galaxy (LTG)
kahkešân-e gune-ye farjâmin
Fr.: galaxie de type tardif
In the → Hubble classification, a galaxy on the left part of the → Hubble sequence. See also → early-type galaxy.
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.
sayârak-e gune-ye M
Fr.: astéroïde de type M
A type of → asteroid that consists of metallic → iron and displays high → albedo (0.10-0.18). M-type asteroids inhabit the middle part of the → asteroid belt.
Magellanic type galaxy
kahkešân-e gune-ye Magellani
Fr.: galaxie de type magellanique
A → metal-poor, → irregular galaxy like the → Large Magellanic Cloud or the → Small Magellanic Cloud. Other examples are: NGC 4449, NGC 4214, and NGC 3109.
→ Magellanic; → type; → galaxy.
hâzandegi-ye gune-ye n
Fr.: conductivité de type n
The conductivity in a semiconductor caused by a flow of electrons, whereas p-type conductivity is caused by a flow of holes.
n standing for → negative; → type; → conductivity.
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.