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

1) To get away; to get free of.
2) An act or instance of escaping.

From M.E. escapen; O.Fr. eschaper, from V.L. *excappare, literally "to get out of one's cape, leave a pursuer with just one's cape," from L. → ex- "out" + L.L. cappa "mantle."

Gorixtan, goriz- "to escape; to flee, run away;" Mid.Pers. virextan; Proto-Iranian *vi-raik, from vi- "apart, asunder" + *raik; Av. raek- "to leave, set free, let off;" Mid./Mod.Pers. reg/rig (in mordé-rig "inheritance"); Skt. ric- "to leave," rinakti "gives up, evacuates;" Gk. leipein "to leave;" L. linquere "to leave;" from PIE *linkw-, from *leikw- "to leave behind" (cf. Goth. leihvan; O.E. lænan "to lend;" O.H.G. lihan "to borrow;" O.N. lan "loan").

The speed an object must attain in order to free itself from the gravitational influence of an astronomical body. It is the minimum velocity for the object to enter a parabolic trajectory. The escape velocity is given by: V_e = (2GM/r)^1/2, where G is the → gravitational constant, M is the mass of the astronomical body, and r is its radius. The escape velocity of the Earth is about 11.2 km s^-1 that of the Moon is 2.4 km s^-1. The escape velocity from the Sun is about 618 km s^-1, and the solar escape velocity from Earth's orbit is about 42.1 km s^-1.

→ escape; → velocity.

An advanced stellar → spectropolarimeter designed and built at the Observatoire Midi-Pyréenées and installed at the → Canada-France-Hawaii Telescope (CFHT). It can obtain a a complete optical spectrum, from 370 nm to 1050 nm, in a single exposure. Among its characteristics: resolving power 65 000 to 80 000; 12% peak throughput (telescope and detector included); continuum subtracted linear and circular polarization spectra of the stellar light (in polarimetric mode). ESPaDOnS is used to study a broad range of important problems in stellar physics: from → stellar magnetic fields to → accretion disks and → extrasolar planets; from inhomogeneities and differential rotation on stellar surfaces to activity cycles and magnetic braking; from microscopic diffusion to turbulence, convection, and circulation in stellar interiors; from abundances and pulsations in stellar atmospheres to stellar winds; from the early phases of stellar formation to the late stages of stellar evolution; from extended circumstellar environments to distant interstellar medium (Donati et al., 2006, Solar Polarization, ASP Conf. Series, 358, 362, eds. R. Casini, B. W. Lites).

Short for Echelle Spectro-Polarimetric Device for the O bservation of Stars; → echelle; → spectro-; → polarimetric; → device; → observation; → star.

1) To found, institute, build, or bring into being on a firm or stable basis.
2) To show to be valid or true; prove.

From O.Fr. establiss-, stem of establir, from L. stabilire "make stable," from stabilis "firm, stable," literally "able to stand," from stare "to stand;" PIE base *sta- "to stand" (cf. Mod.Pers. istâdan "to stand;" O.Pers./Av. sta- "to stand, stand still; set;" Skt. sthâ- "to stand;" Gk. histemi "put, place, weigh;" stasis "a standing still;" Lith. statau "place;" Goth. standan; O.E. standan "to stand," stede "place").

Nešâxtan, nešâzidan "to establish; to fix in the ground, strengthen," from ne- "down, below," → ni-, + šâxtan, šâz-, variants of Mod./Mid.Pers. sâxtan, sâz- "to form, prepare, build, make," ultimately from Proto-Iranian *sac- "to fit, be suitable; to prepare."

1) The act or an instance of establishing.
2) The state or fact of being established.
3) Something established; a constituted order or system.
4) (often initial capital letter) The existing power structure in society; the dominant groups in society and their customs or institutions (Dictionary.com).

→ establish; → -ment.

1) Favorable opinion or judgment; respect or regard.
2) To regard highly or favorably; regard with respect or admiration (Dictionary.com).

M.E. estemen, from M.Fr. estimer, from L. aestimare "to value, determine the value of, appraise," → estimate.

Arj "esteem, honor, dignity; price, worth, value," → credit. Arj nehâdan with nehâdan "to place, put," → position.

Worthy of esteem; deserving respect or admiration. Capable of being estimated (Dictionary.com).

→ esteem; → -able.

1) Statistics: An indication of the value of an unknown quantity based on observed data.
2) Verb of estimate.

From M.Fr. estimer, from L. æstimatus, p.p. of æstimare "to value, estimate."

Barâvard from prefix bar- "on, upon, up," → on-, + âvard past stem of âvardan "to bring, to cause, to produce," → production; verb with infinitive suffix -dan and kardan "to do, make," → verb.

Statistics: The process by which sample data are used to indicate the value of an unknown quantity in a population.

Verbal noun of → estimate.

Statistics: Any quantity calculated from the sample data which is used to give information about an unknown quantity in a population. For example, the sample mean is an estimator of the population mean.

Agent noun of → estimate.

1) That part of the mouth or lower course of a river in which the river's current meets the sea's tide.
2) An arm or inlet of the sea at the lower end of a river (Dictionary.com).

From L. aestuarium "a tidal marsh, mud-beds covered by water at high tides; channel inland from the sea," from aestus "boiling (of the sea), tide, heat," from PIE *aidh- "to burn;" cognates: Gk aithein "to burn," Skt. inddhe "burst into flames," O.Irish aed "fire," O.H.G. eit "funeral pile."

Kešandân, literally "site of tides," from kešand, → tide, + -ân a suffix of place and time.

The most luminous and the most extensively studied of → Luminous Blue Variables. Known also as HD 93308, it lies in the → Trumpler 16→ star cluster of the → Carina Nebula and is about 7,500 to 8,000 → light-years away. η Carina probably began its life as a → very massive star with an initial mass of about 150 → solar masses, and has a current estimated mass of about 90-100 solar masses. The difference has been lost in sudden giant eruptions in the past few thousand years. The so-called → Homunculus Nebula results from the mass ejection by η Carinae during its giant outburst around 1843 when it reached a magnitude of -1 and became the second brightest star in the southern sky. About 1880 it reached magnitude 7 and has remained at this level, although with fluctuations. The 1843 event ejected at least 12 solar masses of gas moving at speeds of up to 650 km s^-1 with a kinetic energy of almost 10⁵⁰ erg. The double-lobed remnant has a mass of about 2.5 solar masses. It is divided by a → torus of cold dust (110 K), about 5 → light-years in radius and 15 solar masses, which was ejected in an earlier event some 1000 years ago. There is strong evidence that η Carinae is a → binary system with a period of about 5.5 years and a projected separation less than 30 → astronomical units (about 0.013 arcsec). A colliding-wind binary is suggested by the → hard X-ray spectrum. The main component has an estimated → mass loss rate of 10^-3 solar masses per year.

Eta (η), Gk. letter of alphabet; the → Carina constellation.

1) To cut, bite, or corrode with an acid or the like; engrave with an acid or the like, as to form a design in furrows that when charged with ink will give an impression on paper.
2) To produce (a design, image, etc.) by this method, as on copper or glass (Dictionary.com).
3) Astro.: To cut or corrode an → iron meteorite with a strong → acid to reveal its hidden → crystalline structure.

From Du. etsen, from Ger. ätzen "to etch," from O.H.G. azzon "to cause to bite, feed," ultimately from PIE root *ed- "to eat;" cf. Av. ad- "to eat;" Mod.Pers. âš "thick brew, soup" (from O.Pers. *āšyā-, Proto-Ir. *HasH- "to eat"); Skt. ad- "to eat;" Gk. edo "I eat;" Lith. edu "I eat;" O.Irish ithim "I eat;" O.E. etan, O.H.G. essan, Ger. essen "to eat."

Bâ tizâb kandan, literally "to dig with acid," from bâ "with," tizâb "acid," kandan "to dig;" ecidan, from E. etch, cognate with Pers. âš, as above.

1) The act or process of making designs or pictures on a metal plate, glass, etc., by the corrosive action of an acid instead of by a burin.
2) An impression, as on paper, taken from an etched plate.
3) The design so produced (Dictionary.com).
4) The act or process of cutting a smooth cross section of a → meteorite with → acid to reveal its → crystal structure.

Verbal noun of → etch.

A colorless, odorless → hydrocarbon, C₂H₆, which occurs with → methane in natural gas.

From eth-, from → ethyl, + -ane a suffix used in names of hydrocarbons of the methane or paraffin series.

An → alcohol having molecular formula C₂H₅OH. It is a colorless inflammable liquid with a characteristic odor. Ethanol is produced by fermentation of sugar: C₆H₁₂O₆ → 2 C₂H₅OH + 2 CO₂. It is the active constituent of alcoholic beverages. It is used as a fuel and as a solvent in the extraction of specific substances. It is also known as → ethyl alcohol. Ethanol in the → interstellar medium was first detected toward the → Sagittarius B2 molecular cloud at 82.265, 90.118, and 104.809 GHz (B. Zuckerman et al. 1975, ApJ 196, L99).

Short for → ethyl alcohol.

1) Physics: A hypothetical medium filling all space formerly postulated to account for the propagation of → electromagnetic radiation through space. In order to facilitate description and to provide a physical explanation of various phenomena involving action at a distance and electromagnetism, a medium had been postulated with mechanical properties adjusted to provide a consistent theory. In 1887 Michelson and Morley attempted to measure the motion of the Earth through the ether. No such motion was detected. The → Michelson-Morley experiment has been repeated under different conditions, but the hypothesis of a stationary ether through which the Earth moves is not verified.
2) The substance supposed by Aristotle to constitute stars and fill the outer space.
3) Chemistry: A family of organic compounds with the general formula R-O-R', where R and R' are hydrocarbon radicals. In particular diethyl ether, C₂H₅OC₂H₅, which is a volatile colorless liquid with a pleasant smell.

From L. æther "the upper air, pure air," from Gk. aither "upper air," from aithein "to burn, shine."

A hypothesis put forward to explain the null measurement of the → ether drift. According to this hypothesis, the Earth somehow drags the ether with it as our planet rotates on its axis and revolves around the Sun. However, the ether drag hypothesis contradicts results from several experiments, including the → aberration of starlight.

→ ether; → drag.

1) The hypothetical motion of the supposed → ether relative to the Earth. The → Michelson-Morley experiment found no ether drift. An analogy is given by a boat drifting in a fast-flowing river due to the river's current. With the same power, the speed would be slower when sailing across the stream. Moreover, in order to reach directly opposite the starting point, the boat would have to be headed somewhat upstream. See also the → ether drag.
2) The motion of the Earth relative to the → rest frame defined by the → cosmic microwave background radiation.

→ ether; → drift.

A combining form meaning "race, culture, people."

From Gk. ethnos "people, nation, class, tribe."

Qowm- loan from Ar. qaum "people, tribe, family."