The Eagle. A constellation on the celestial equator representing an eagle (R.A. about 19h30, Dec. about +5 deg). It is marked by the bright star → Altair (α Aquilae). Abbreviation: Aql, genitive form: Aquilae.
L. aquila "black eagle," fem. of aquilus "dark colored" (bird).
Šâhin "eagle," Av. saêna- "eagle," Skt. śyená- "eagle, falcon, hawk".
Fr.: Rift de l'Aigle
A long, dark structure located close to the → Galactic plane and occupying an area between longitudes l ~15° and ~35° and latitudes b ± 10° in the constellations Aquila, Serpens, and eastern Ophiuchus. The Aquila Rift is a complex of dust and → molecular clouds making part of → Gould's Belt in the → Orion Arm. The mass of the molecular gas, derived from → carbon monoxide (CO) observations (Dame et al. 2001, ApJ 547, 792), is in the range ~ 1-3 x 105 → solar masses. A distance of ~260 pc has been estimated for the Aquila Rift, but it is uncertain. Recent Herschel observations have revealed a filamentary structure in the Aquila Rift and the presence of a population of → pre-stellar cores as well as → young stellar objects (André et al. 2010, A&A 518, L102; Bontemps et al. 2010, A&A 518, L85; Könyves et al. 2010, A&A 518, L106).
L. ara "fire altar," from PIE as- "to burn".
Âtašdân "a hearth, a fire-place; a movable coal grate," from âtaš "fire" (from Mid.Pers. âtaxš, âzar-, O.Pers. *âtar-, Av. âtar-, from Indo-Iranian *âtar-, compare with L. âter (feminine âtra) "black" (from "blackened by fire"); PIE *âter) + -dân suffix denoting recipient.
axtaršenâsi-ye Arabi (#)
Fr.: astronomie arabe
The astronomical activities that took place from the 8th to the 14th century in the Middle East, Central Asia, North Africa, and Moorish Spain. Arab/Arabic is not meant as an ethnic but rather a linguistic term. In fact a large number of Non-Arab scholars, mainly Persians, Mongols, and Spanish people, wrote their works in Arabic. Even so, many astronomical works were also produced in the other languages of this civilization, especially Persian and in the later centuries Turkish. For example, the main → zijs were originally written in Persian, a notable example being the Zij of Ulugh Beg (c. A.D. 1394-1449), a landmark in precise observations before the Renaissance. Therefore, the term Arabic astronomy is misleading. It also creates a disparity with respect to Western scholars who wrote in Latin. The term "Latin astronomy" is meaningless and as far as these scholars are concerned, the Latin adjective is not specified. For example, the expressions like "the Latin astronomer Copernicus," "the Latin physicist Newton," or "the Latin philosopher Leibniz" are not used. See also → Islamic astronomy.
M.E. arabik, from O.Fr. arabique, from L. Arabicus; → astronomy.
Fr.: point d'Arago
Named for François Arago (1786-1853), French physicist; → point
1) Based on individual will or choice rather than by reason or necessity.
M.E., from O.Fr. arbitraire or directly from L. arbitrarius "depending on the will, uncertain," from → ad- "to" + baetere "to come, go."
Fr.: constante arbitraire
A constant quantity in → equations which takes various values but which remains unaffected by the changes in the values of the → variables of the equation. Most → differential equations have more than one → solution. In general, the number of arbitrary constants of an ordinary differential equation is given by the → order of the highest → derivative.
1) In → graph theory, a → rooted tree
that has a natural orientation in which all → paths
are directed away from the → root. More specifically, a
→ directed graph in
which, for a → vertex u, called the
→ root, and any other vertex v,
there is exactly one → directed path
from u to v.
Šâkedâri, nous from šâkedâr, → arborescent.
Having the shape or characteristics of a tree in growth, structure, or appearance.
From Fr. arborescent, from L. arborescent-, p.p. of arborescere "to grow into a tree," from arbor, arboris "tree."
1) General: Something shaped like a → curve
or → arch.
M.E. ark, from M.Fr. arc "bow," from L. arcus "bow, arch" (cf. Goth. arhwazna "arrow," O.E. earh), PIE *arqu- "bowed, curved."
Kamân "arc, bow" from Mid.Pers. kamân, related to xam "curve," cf. Breton kamm "curved, bent," Gk. kampe "a corner, a joint," L. campus "a field," Lith. kampus "corner," PIE *kamb- "to bend, crook."
kamân-daqiqé, daqiqe-ye kamâni
Fr.: minute de degré
A unit of angular size equal to 1/60 of a degree.
arc of light
Fr.: arc de lumière
arc of separation
Fr.: arc de séparation
arc of vision
Fr.: arc de vision
kamân-sâniyé, sâniye-ye kamâni
Fr.: seconde de degré
A unit of angular size equal to 1/3.600 of a degree.
Fr.: spectre d'étincelle
The spectrum produced by an atom or mixture of atoms as a result of vaporization within an electric arc generated between two electrodes.
1) A curved structure, normally in the vertical plane, that spans an opening.
M.E. arch(e), from O.Fr. arche "arch of a bridge," from L. arcus "a bow," → arc.
Taq "arch," from tâk, contraction of târak, → vertex.
The study that deals with the astronomical knowledge of prehistoric peoples (season events, calendars, observing sites, astronomical alignments) and its influence on their cultures and societies (mythologies, religions, life). Archaeoastronomy covers the intersection between astronomy and archaeology. Same as → astroarchaeology, megalithic astronomy.
Archeoastronomy, from L. archaeo-, archeo "ancient; earlier; primitive," from Gk. arkhaio-, from arkhaios "ancient" + → astronomy.
Bâstânaxtaršenâsi, from bâstân "ancient" + axtaršenâsi, → astronomy.
Fr.: arché-, archi
A prefix meaning "principal, prior, original, first, early" Same as archi-. → archetype.
From Gk. arkhe-, from arckhon "ruler," noun use of p.p. of arkhein "to rule."
Sar-, from sar "top, summit, the capital of a pillar," → head.
Fr.: amas des Arches
One of the three → Galactic center clusters supposed to be the densest young → massive star cluster in the Milky Way. It contains the richest collection of → O stars and → WN Wolf-Rayet stars in any cluster in the Galaxy, thus representing the largest collection of the most massive stars in the Galaxy. With its estimated age of 2-3 million years, the Arches cluster is the youngest of the massive clusters in the Galactic center. → Quintuplet cluster; → Central cluster (Figer et al. 2002, ApJ 581, 258; and 1999, ApJ 525, 750).
Arches, from the presence of Galactic center thermal → arched filaments, about 100 → light-years in projection from the Galactic center (Morris & Yusef-Zadeh, 1985, AJ 90, 2511), from M.E. arche, O.Fr. arche "arch of a bridge," from L. arcus, → arc; → cluster.