The Serpent Holder. An extensive constellation located in the equatorial regions of the sky at about 17h 20m right ascension, 5° south declination. Although this constellation is not part of the zodiac, the Sun passes through it in December each year. Ophiuchus contains five stars of second magnitude and seven of third magnitude. Other designations: Serpent Bearer, Serpentarius. Abbreviation: Oph, genitive: Ophiuchi.
L. Ophiuchus, from Gk. ophioukhos "holding a serpent," from ophis "serpent" + echein "to hold, have, keep." The most recent interpretation is that the figure represents the great healer Asclepius, a son of the god Apollo, who learned the secrets of keeping death at bay after observing one serpent bringing another healing herbs. To prevent the entire human race from becoming immortal under Asclepius' care, Zeus killed him with a bolt of lightning, but later placed his image in the heavens to honor his good works.
Mâr-afsâ "a tamer or charmer of serpents; one who cures the snake-bitten by incantation," from mâr "snake, serpent" (Mid.Pers. mâr "snake;" Av. mairya- "snake, serpent") + afsâ agent noun of afsâyidan, from afsun "incantation" (Mid.Pers. afsôn "spell, incantation," afsûdan, afsây- "to enchant, protect by spell").
Fr.: phase orbitale
In → photometry of → binary stars or → two-body systems, the number of whole or fractional orbits completed, from the point the photometry begins. The point is conventionally chosen as the position at which the → primary star eclipses the → secondary star, and therefore the → light curve is at a minimum. The phase keeps counting indefinitely, thus the secondary star gets eclipsed at phase 0, 1, 2, 3, and so on. At these phases the primary lies between the secondary and the observer. An orbital phase of 0.5 corresponds to halfway through the binary orbit, 0.75 is three-quarters the way through, and so on.
orbital phase curve
xam-e fâz-e madâri
Fr.: courbe de la phase orbitale
In astronautics, the study of satellite orbits and precise determination of orbital elements which gives the exact position of the satellite.
order of a graph
Fr.: ordre de graphe
1) A child who has lost both parents through death, or, less commonly, one parent.
M.E., from L.L. orphanus "destitute, without parents," from Gk. orphanos "bereaved;" akin to L. orbus "bereaved," Skt. arbhah "weak, child," Armenian orb "orphan," O.Irish orbe "heir," O.C.S. rabu "slave," Ger. Erbe, O.E. ierfa "heir," O.H.G. arabeit, Ger. Arbeit "work," O.E. earfoδ "hardship, suffering, trouble."
Yatim "fatherless," from Ar.
Fr.: proto-étoile orpheline
A → protostellar object which has been dynamically ejected from a newborn → multiple star system, either into a tenuously bound orbit or into an escape, thus depriving it from gaining much additional mass. Recent observations have shown that → Class I protostellar sources have a population of distant companions at separations ~ 1000 to 5000 → astronomical unit (AU)s. Moreover, the companion fraction diminishes as the sources evolve. According to N-body simulations of unstable → triple systems embedded in dense cloud cores, many companions are ejected into unbound orbits and quickly escape, but others are ejected with insufficient momentum to climb out of the potential well of the cloud core and associated binary. These loosely bound companions reach distances of many thousands of AU before falling back and eventually being ejected into escapes as the cloud cores gradually disappear (B. Reipurth et al. 2010, arXiv:1010.3307).
sepehr-e âbusandé, kore-ye ~
Fr.: sphère osculatrice
For a curve C at a point p, the limiting sphere obtained by taking the sphere that passes through p and three other points on C and then letting these three points approach p independently along C.
out of phase
The condition of two oscillators that have the same frequency but different phases. Opposed to → in phase.
fizik-e zarreyi (#)
Fr.: physique des particules
The branch of physics that deals with the smallest known structures of matter and energy in order to understand the fundamental particles and forces of nature.
The fifteenth of Jupiter's known satellites, orbiting at 23,660,000 km from Jupiter; also known as Jupiter VIII. Its diameter is 36 km and orbital period 744 days.
In Gk. mythology, Pasiphae was the wife of Minos and mother, by a white bull, of the Minotaur.
Pertaining to, situated in, or constituting the periphery.
Adj. of → periphery.
Fr.: réponse périphérique
In a charge-coupled device, the detection of charge collected by the transport register rather than by the image-sensing elements.
Fr.: vision périphérique
In optics, the ability to see over large angles of view.
The external surface or boundary of a body. The circumference or perimeter of any closed figure.
From, M.E., from O.Fr. periferie, from L.L. peripheria, from Gk. peripheria "circumference, outer surface," literally "a carrying around," from peripheres "rounded, moving round," peripherein "to carry or move round," from → peri- "round about" + pherein "to carry;" cognate with Pers. bordan "to carry, lead," as below.
Pirâbar, from pirâ-, → peri-, + bar present stem of bordan "to carry, lead" (Mid.Pers. burdan, O.Pers./Av. bar- "to bear, carry," barəθre "to bear (infinitive)," Skt. bharati "he carries," Gk. pherein, L. fero "to carry;" PIE base *bher- "to carry").
Fr.: potentiel hydrogÃ¨ne
A → logarithmic measure of → hydrogen ion concentration, originally defined pH = log10 (1/[H+]), where [H+] is the concentration of hydrogen ions in → moles per liter of solution. The hydrogen ion concentration in pure water around room temperature is about 1.0 × 10-7 moles. Therefore, a pH of 7 is considered "neutral," because the concentration of hydrogen ions is exactly equal to the concentration of → hydroxide (OH-) ions produced by → dissociation of the → water. Increasing the concentration of hydrogen ions above 1.0 × 10-7 moles produces a solution with a pH of less than 7, and the solution is considered → acidic. Decreasing the concentration below 1.0 × 10-7 moles produces a solution with a pH above 7, and the solution is considered → alkaline or → basic. The neutral pH is different for each → solvent. For example, the concentration of hydrogen ions in pure ethanol is about 1.58 × 10-10 moles, so ethanol is neutral at pH 9.8. A solution with a pH of 8 would be considered acidic in ethanol, but basic in water.
From Ger. PH, introduced by Danish biochemist S.P.L. SÃ¸rensen (1868-1939) in 1909, from P, for Ger. Potenz "power, potency," and H, symbol of → hydrogen.
Phad (γ UMa)
Phad, from Ar. al-Fakhidh (ad-Dubb) (
Faxez, from Ar., as above.
A hypothetical → planet which once was postulated to have existed between the orbits of → Mars and → Jupiter and its destruction supposedly led to the formation of the → asteroid belt. The idea of such a hypothetical planet was first put forward by the German astronomer Heinrich Wilhelm Olbers (1758-1840).
In Greek mythology Phaeton was the sun god Helios. Phaeton tried to drive his father's solar chariot but crashed after almost setting fire to the whole earth.
The tube or cavity, with its surrounding membrane and muscles, that connects the mouth and nasal passages with the esophagus (Dictionary.com). → throat.
From Gk pharynx (genitive pharyngos) "windpipe, throat."
Halq, loan from Ar.
1, 2) fâz; 3) simâ
1) A particular stage or point in a course, development,
or graph varying cyclically; the fractional
part of the period through which the time has advanced, measured from
some arbitrary origin. Phase
is measured like an angle, when a complete cycle is equivalent to a
phase of 360Â° (or 2π radians), or, sometimes, as a number between 0
and 1. Two or more waves of the same frequency are
→ in phase when their maxima and minima take place at the same
moments. Otherwise, they are said to be → out of phase
or that they have a → phase difference.
Mod.L. phases, plural of phasis, from Gk. phasis "appearance," from stem of phainein "to show, to make appear."
1) Fâz, loanword from Fr., as above.