An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 3079 Search : on
carbon dioxide
  دی‌اکسید ِ کربون، گاز کربونیک   
dioksid-e karbon, gâz karbonik (#)

Fr.: dioxyde de carbone   

CO2, also called carbonic acid gas. A colorless gas which occurs in the atmosphere playing an essential part in animal respiration and the growth of green plants. → photosynthesis, → carbon cycle. It is formed by the → oxidation of carbon and carbon compounds. Carbon dioxide is the most important → greenhouse gas produced by human activities, primarily through the combustion of fossil fuels. Its concentration in the Earth's atmosphere has risen by more than 30% since the Industrial Revolution. CO2 forms a solid at -78.5 °C at atmospheric pressure, and is used as a refrigerant in this form as a dry ice for the preservation of frozen foods. As carbon dioxide gas is heavier than air and does not support combustion, it is used in fire extinguishers.
CO2 is present in the → interstellar medium and is one of the main → molecules in → comets.

carbon; → dioxide.

carbon monoxide (CO)
  مونوکسید ِ کربون   
monoksid-e karbon (#)

Fr.: monoxyde de carbone   

A colorless, odorless, very poisonous gas which burns in air with a bright blue flame to form → carbon dioxide. CO gives rise to a violent explosion when ignited in air in certain proportions. It occurs in coal gas and in the exhaust fumes of motor engines. Melting point -207 °C; boiling point -191.1 °C.
Carbon monoxide is the most important → molecule found in the → interstellar medium, and is produced through several chemical reactions, → CO formation. It was discovered in 1970 by R. Wilson and A. Penzias of Bell Laboratories, using the 11-m telescope of the National Radio Astronomy Observatory (NRAO) in the direction of the → Orion nebula. Because the CO line is so intense and widely distributed in space, this molecule is a most useful tool for tracing the ISM. In addition, measurement of its rare isotopes have shown that the main line 12C16O (wavelength 2.6 mm, 115 GHz) is → optically thick, that is the → column density of the molecule is so high that the material becomes opaque at the transition frequency. Moreover, the upper-energy levels of the CO molecule are easily excited by collision with → molecular hydrogen. The combination of high → optical depth and the ease of → excitation imply that CO emission brightness will accurately reflect the local gas temperature. CO is also one of the principal molecules detected in → comet nuclei.

carbon; → mono-; → oxide.

carbon star
  ستاره‌ی ِ کربونی   
setâre-ye karboni

Fr.: étoile carbonée   

A class of → red giant stars whose spectra show strong → molecular bands of → carbon compounds.

carbon; → star.

carbon-14
  کربن-۱۴   
karbon-14

Fr.: carbon-14   

A radioactive isotope of carbon, whose nucleus contains 6 protons and 8 neutrons; also called → radiocarbon. 14C is naturally produced in the atmosphere when a neutron created by a cosmic ray hits the nucleus of an atom of nitrogen-14. The nucleus absorbs the neutron and ejects a proton, thereby transforming itself into 14C. It decays back to nitrogen, with a half-life is 5730 years, after emitting an electron (146C → 147N + e- + νe). See also → radiocarbon dating.

carbon; → four + -teen, an inflected form of the root of → ten.

carbon-enhanced metal-poor star (CEMP)
  ستاره‌ی ِ کم‌فلز ِ کربون بلندیده   
setâre-ye kamfelez-e karbon bolandidé

Fr.: étoile pauvre en métaux enrichie en carbon   

A star that presents very low → iron  → abundances [Fe/H] < -4 but an → anomalous richness in carbon. CEMP stars have been defined as a subset of → metal-poor stars that exhibit elevated [C/Fe] ≥ +1.0. It has been recognized that ~15-20% of stars with [Fe/H] < -2.0 are carbon enhanced. This fraction rises to 30% for [Fe/H] < -3.0, to 40% for [Fe/H] < -3.5, and ~75% for [Fe/H] < -4.0. This increasing trend of CEMP-star frequency with declining [Fe/H] is confirmed by the observation of many thousands of CEMP stars (Daniela Carollo + ApJ 2014, 788, 180). See also → extremely metal-poor star (EMPS)

carbon; → enhance; → metal; → metal; → poor; → star.

carbonaceous
  کربونی، کربندار   
karboni, karbondâr

Fr.: carboné   

Containing or composed of carbon.

From → carbon + -aceous, from L. -aceus "-ous."

Karboni, adj. from karbon, → carbon; karbondâr "having carbon," with -dâr "having, possessor," from dâštan "to have, to possess;" O.Pers./Av. root dar- "to hold, keep back, maintain, keep in mind;" cf. Skt. dhr-, dharma- "law;" Gk. thronos "elevated seat, throne;" L. firmus "firm, stable;" Lith. daryti "to make;" PIE base *dher- "to hold, support."

carbonaceous chondrite
  کوندریت ِ کربونی   
kondrit-e karboni

Fr.: chondrite carbonée   

A rare type of → stony meteorite having a higher → carbon content than other classes of meteorite. They represent only ~5% of the known meteorites. Their bulk composition is mainly → silicates, → oxides and sulfides, whilst the minerals → olivine and serpentine are characteristic. The six classes of carbonaceous chondrites are: → CI chondrites, CM chondrites, CV chondrites, CO chondrites, CK chondrites, CR chondrites, CH chondrites, and CB chondrites.

carbonaceous; → chondrite.

carbonyl group
  گروه ِ کربونیل   
goruh-e karbonil (#)

Fr.: groupe carbonyl   

The radical -C=O, which occurs in several compounds, such as → aldehydes and ketones.

From → carbon + -yl a suffix used in the names of some radicals; → group.

cardinal direction
  سوی ِ اگرا   
su-ye agrâ

Fr.: point cardinal   

Any of the four principal directions or points of the compass, → north, → east, → south, and → west. See also: → cardinal point.

cardinal; → direction.

Carrington rotation
  چرخش ِ کرینگتون   
carxeš-e Carrington

Fr.: rotation de Carrington   

A system for counting rotations of the Sun based on the mean → synodic rotation period of the Sun. Initially, Lord Carrington determined the solar rotation rate by watching low-latitude → sunspots. He defined a fixed solar coordinate system that rotates in a sidereal frame exactly once every 25.38 days. This means that the solar rotation period, as viewed from the Earth, is assumed to be constant. However, the synodic rotation rate varies during the year because of the changing speed of the Earth in its orbit and the mean synodic period is about 27.2753 days. Carrington rotation number 1 began on November 9, 1853.

Named for Richard C. Harrington (1826-1875), British astronomer, who initiated the system; → rotation.

cascade transition
  گذرش ِ پی‌شاری   
gozareš-e peyšâri

Fr.: transition en cascade   

A photon generation mechanism in an atom in which a transition initiates a series of secondary transitions from lower electronic levels.

cascade; → transition.

Cassini division
  شکاف ِ کاسینی   
šekâf-e Cassini (#)

Fr.: division de Cassini   

The main dark gap, 4,700 km wide, which divides Saturn's outermost A and B rings.

Named after Jean-Dominique Cassini (1625-1712), French astronomer of Italian origin, who discovered the division in 1675; → division.

catalog position
  نهش ِ کاتالوگی   
neheš-e kâtâlogi

Fr.: position catalogue   

Same as catalog place and → mean catalog place.

catalog; → position.

categorical proposition
  گزاره‌ی ِ کتاگریک   
gozâre-ye katâgorik

Fr.: proposition catégorique   

In a → syllogism, a → proposition or statement that deals with inclusion or exclusion of members of → subject classes in → predicate classes. Categorical propositions are of four basic forms, see → Aristotelian form.

categorical; → proposition.

cation
  کاتیون   
kâtion (#)

Fr.: cation   

Chemistry: A → positively charged → ion that is attracted to the → cathode in electrolysis. Any positively charged atom or group of atoms (opposed to → anion).

From cat-, → cathod, + → ion.

Cauchy's equation
  هموگش ِ کوشی   
hamugeš-e Cauchy

Fr.: équation de Cauchy   

A relationship between the → refractive index (n) and the wavelength of light (λ) passing through a medium. It is commonly stated in the following form: n = A + B2 + C4, where A, B, and C are constants characterizing the medium. The two-component Cauchy equation is n = A + B2, from which the dispersion becomes dn/dλ = -2B3 showing that dispersion varies approximately as the inverse cube of the wavelength. The dispersion at 4000 A will be about 8 times as large as at 8000 Å.

Named after Augustin Louis Cauchy (1789-1857), French mathematician and physicist who found the first equation of dispersion in 1836; → equation.

causation
  بنارش   
bonâreš

Fr.: relation de cause à effet   

1) The act or process of causing; the act or agency which produces an effect.
2) The relation of → cause to → effect.

Verbal noun from → cause.

celestial horizon
  افق ِ آسمانی   
ofoq-e âsmâni (#)

Fr.: horizon céleste   

A great circle on the → celestial sphere having a plane that passes through the center of the Earth at a right angle to the line formed by an observer's → zenith and → nadir.

celestial; → horizon.

celestial longitude
  درژنای ِ آسمانی   
derežnâ-ye âsmâni

Fr.: longitude céleste   

Angular distance to an object measured eastward along the → ecliptic from the → vernal equinox.

celestial; → longitude.

Derežnâ, → longitude; âsmânicelestial.

center of attraction
  مرکز ِ درکشش   
markaz-e darkašeš

Fr.: centre d'attraction   

A point toward which a force on a body is always directed.

center; → attraction.

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