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: 60 Search : orbit
orbital phase
  فاز ِ مداری   
fâz-e madâri

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.

orbital phase curve
  خم ِ فاز ِ مداری   
xam-e fâz-e madâri

Fr.: courbe de la phase orbitale   

The photometric variability induced by the → orbital motion in a → two-body system.

orbital; → phase.

orbital plane
  هامُنِ مداری   
hâmon-e madâri

Fr.: plan orbital   

The plane defined by the motion of an object about a primary body.

orbital; → plane .

orbital precession
  پیشایان ِ مداری   
pišâyân-e madâri

Fr.: précession orbitale   

Same as → relativistic precession.

orbital; → precession.

orbital resonance
  باز‌آوایی ِ مداری   
bâzâvâyi-ye madâri

Fr.: résonance orbitale   

The situation in which two orbiting objects exert a regular, periodic gravitational influence on each other and therefore their orbital frequencies are related by a ratio of two small → integers. Orbital resonance often results in an unstable interaction in which bodies exchange momentum and shift orbits until the resonance disappears. The resonance increases the eccentricity until a body approaches a planet too closely and the body is slung away.

orbital; → resonance.

orbital shrinkage
  درهم‌کشیدگیِ مداری   
darhamkešidegi-ye madâri

Fr.: rétrécissement de l'orbite   

The lessening in size of the orbit of a binary system composed of two compact objects (pulsars/black holes) due to loss of energy by the system, in particular through gravitational wave radiation. This loss will cause the two objects to approach closer to each other, the orbital period decreases and the binary companions will eventually merge.

orbital; shrinkage, from shrink, from M.E. schrinken, O.E. scrincan, from P.Gmc. *skrenkanan (cf. M.Du. schrinken, Swed. skrynka "to shrink."

Darhamkešidegi "shrinking, shriveling," from state noun of < i>darhamkešidé, from darham- "together, in eachother, toward eachother" (For etymology of dar-, → in-; for etymology of ham-, → com-) + kešidé "drawn, shrivelled, wrinkled," from Mod./Mid.Pers. kešidan, kašidan "to draw, protract, trail, drag, carry," dialectal Yaqnavi xaš "to draw," Qomi xaš "streak, stria, mark," Lori kerr "line;" Av. karš- "to draw; to plow," karša- "furrow;" Proto-Iranian *kerš-/*xrah- "to draw, plow;" cf. Skt. kars-, kársati "to pull, drag, plow;" Gk. pelo, pelomai "to move, to bustle;" PIE base kwels- "to plow;" madâri, → orbital.

orbital speed
  تندای ِ مداری   
tondâ-ye madâri

Fr.: vitesse orbitale   

Same as → orbital velocity.

orbital; → speed.

orbital velocity
  تندایِ مداری   
tondâ-ye madâri

Fr.: vitesse orbitale   

The velocity of an object in a given orbit around a gravitating mass. For a perfect circular orbit, the velocity is described by the formula V =√[G(M + m)/r], where G is the gravitational constant, M the mass of the primary gravitating body, m the mass of the orbiting object, and r the radius of the orbit.

orbital; → velocity.

orbitography
  مدارنگاری   
madârnegâri

Fr.: orbitographie   

In astronautics, the study of satellite orbits and precise determination of orbital elements which gives the exact position of the satellite.

orbital + → -graphy.

osculating orbit
  مدارِ آبوسنده   
madâr-e âbusandé

Fr.: orbite osculatrice   

The Keplerian orbit that a satellite would follow after a specific time t if all forces other than central inverse-square forces ceased to act from time t on. An osculating orbit is tangent to the real, perturbed, orbit and has the same velocity at the point of tangency.

osculating; → orbit.

parabolic orbit
  مدار ِ سهمی   
madâr-e sahmi

Fr.: orbite parabolique   

An orbit whose overall shape is like a parabola; it is the limiting case between an elliptical orbit (eccentricity less than 1) and a hyperbolic orbit (eccentricity larger than 1). The speed necessary to form a parabolic orbit is known as the escape velocity.

parabolic; → orbit.

polar orbit
  مدار ِ قطبی   
madâr-e qotbi (#)

Fr.: orbite polaire   

A spacecraft orbit that passes over, or close to, the geographic poles of the Earth or some other solar system object.

polar; → orbit.

polar orbiting satellite
  ماهواره با مدار ِ قطبی   
mâhvâré bâ madâr-e qotbi

Fr.: satellite en orbite polaire   

A satellite that revolves around the Earth in an almost north-south orbit, passing close to both poles. The orbits are sun synchronous, allowing the satellite to cross the equator at the same local time each day. These satellites orbit at a height of 830-880 km and take about 100 minutes to complete a turn around the Earth.

polar; → orbit; → satellite.

prograde orbit
  مدار ِ فرارو   
madâr-e farârow

Fr.: orbite prograde   

Same as →prograde motion.

prograde motion; → orbit.

resonance orbit
  مدار ِ باز‌آوایی   
madâr-e bâzâvâyi

Fr.: orbite de résonance   

An orbit which is in → orbital resonance with another orbit.

resonance; → orbit.

retrograde orbit
  مدار ِ پسرفت   
madâr-e pasraft

Fr.: orbite rétrograde   

An orbit with an inclination between 90° and 270° such as those of some comets and small asteroids orbiting the Sun.

retrograde; → orbit.

spin-orbit coupling
  جفسری ِ اسپین-مدار، جفتش ِ ~   
jafsari-ye espin-madâr, jofteš-e ~

Fr.: couplage spin-orbite   

1) Astro.: A relationship between the orbital period of one body around another and its rotational period on its axis. The relationship results from tidal forces between the two bodies. For example, the rotation period of the Moon equals its revolution period around the Earth.
2) Quantum mechanics: The interaction between a particle's → spin angular momentum and its → orbital angular momentum.

spin; → orbit; → coupling.

stationary orbit
  مدار ِ ایست‌ور   
madâr-e istvar

Fr.: orbite stationnaire   

An orbit in which the satellite revolves about the primary at the angular rate at which the primary rotates on its axis. From the primary, the satellite thus appears to be stationary over a point on the primary.

stationary; → orbit.

synchronous orbit
  مدار ِ همگام   
madâr-e hamgâm

Fr.: orbite synchrone   

synchronous rotation.

synchronous; → orbit.

tadpole orbit
  مدار ِ وگیزی   
madâr-e vagizi

Fr.: orbite en forme de têtard   

A shorter → horseshoe orbit confined to the → Lagrangian points L4 or L5.

tadpole; → orbit.

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