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

In logic, a → proposition that may be either true or false, and is not necessarily one or the other.

Noun of → contingent.

1) Dependent for existence, occurrence, character, etc., on something not yet certain; conditional.
2) Liable to happen or not; uncertain; possible.
3) Logic: Describing a → proposition that is → true in some possible circumstances and → false in others. For example, "it snowed in Paris on 15 December 2000" is contingent: it is true, but it might have been false. On a → truth table a contingent proposition is one that is true for some possible → truth values of its constituent parts and false for others. See also → non-contingent.

M.E., from M.Fr. contingent and directly from L. contingentem (nominative contingens) "happening, touching," pr.p. of contingere "to touch," → contact.

Âmarsân, agent noun from *âmarsidan "to touch," related to parmâsidan "to touch, feel," → contact, Mid.Pers. marz "contact, touching," marzitan "to touch," Mod.Pers. mâlidan "to rub," Av. marəz- "to rub, wipe," marəza- "border, district," Mod.Pers. marz "border;" ultimately from Proto-Ir. *Hmars- "to touch."

The act or state of continuing; the state of being continued.

Verbal noun of → continue + → -tion.

1) (v.intr) To go on or keep on without interruption as in some course or action.
2) (v.trans) To cause to remain in a particular condition.

M.E. contynuen, from O.Fr. continuer, from L. continuare "to make all one, join together, make or be continuous," from continuus "uninterrupted," from continere "to be uninterrupted," literally "to hold together," from → con- + tenere "to hold," cognate with Pers. tanidan, → tension.

1) Peydâštan, from pey "after; pursuit; track; step," → tracking, + dâštan "to have, hold, maintain," → access.
2) Peydâdan, from pey, as above, + dâdan "to give, yield, grant, command," → yield.

Continuing to happen or exist for a long time. Occurring many times.

Past participle of → continue.

In mathematics, a fraction whose numerator is an integer and whose denominator is an integer plus a fraction whose numerator is an integer and whose denominator is an integer plus a fraction and so on.

→ continued; → fraction.

1) General: Uninterrupted in extent, sequence, or time.
2) Math.: A line or curve that extends without a break. → continuous function.

From L. continuus "uninterrupted," from contin(ere) "to hold together, retain," → continue, + -uus verbal adj. suffix.

Peyvasté "continous," peyvastan "to connect, join," Mid.Pers. paywastan, from *pati-basta-, from suffix pati- (Mid.Pers. pât-,from O.Pers. paity "agaist, back, opposite to, toward, face to face, in front of," Av. paiti, akin to Skt. práti "toward, against, again, back, in return, opposite," Pali pati-, Gk. proti, pros "face to face with, toward, in addition to, near;" PIE *proti) + basta- "tied, shut" (Av./O.Pers. band- "to bind, fetter," banda- "band, tie," Skt. bandh- "to bind, tie, fasten," PIE *bhendh- "to bind," cf. Ger. binden, E. bind), cf. Skt. prati-bandh- "to tie."

Data that can take any value along a continuum (e.g. air temperature between two upper and lower boundaries) as opposed to → discrete data, which can only take integer values.

→ continuous; → data.

The function y = f(x) is called continuous at the point x = x₀ if it is defined in some neighborhood of the point x₀ and if lim Δy = 0 when Δx → 0.

→ continuous; → function.

An electromagnetic spectrum in which emitted or absorbed radiation is present continuously over all wavelengths in a given range.

→ continuous; → spectrum.

Binâb, → spectrum; peyvasté→ continuous.

A variable which has changes continuously, in contrast to → discrete variables.

→ continuous; → variable.

A → quantum walk taking place entirely in the position space. Continuous-time quantum walk was introduced by E. Farhi & S. Gutmann (1998, Phys. Rev. A 58, 915).

→ continuous; → time; → quantum; → walk.

A continuous extent or succession, which has no discrete parts, as the continuum of real numbers as opposed to the sequence of discrete integers. → continuum emission.

From L. neut. of continuus, → continuous

Peyvastâr, from peyvast past tense stem of peyvastan "to connect, join," Mid.Pers. paywastan, from *pati-basta-, from suffix pati- (Mid.Pers. pât-, from O.Pers. paity "agaist, back, opposite to, toward, face to face, in front of," Av. paiti, akin to Skt. práti "toward, against, again, back, in return, opposite," Pali pati-, Gk. proti, pros "face to face with, toward, in addition to, near;" PIE *proti) + basta- "tied, shut" (Av./O.Pers. band- "to bind, fetter," banda- "band, tie," Skt. bandh- "to bind, tie, fasten," PIE *bhendh- "to bind," cf. Ger. binden, E. bind), cf. Skt. prati-bandh- "to tie." + -âr suffix forming verbal noun.

A continuous radiation produced by three processes: radiative recombination due to transition between electron free-free states, two-photon decays of metastable levels, and thermal bremsstrahlung.

→ continuum; → emission.

The transfer of photon momentum to free electrons. The acceleration by → continuum emission can be given by: a_c = (σ/m)(L_*/4πR²c), where σ is the → Thomson scattering  → cross section, m is the mass per free electron, L_* is → stellar luminosity, R_* is radius, and c the → speed of light. The ratio of a_c to the → surface gravity is ≅ 2 × 10^-5L_*/M_*, with M_* and L_* in solar units. The atmosphere is is stable if a_c very smaller than g_grav. If L_* is above the → Eddington limit, the radiation pressure in the continuum leads to very heavy → mass loss and thus to expanding envelopes (K.S. de Boer & W. Seggewiss, 2008, Stars and Stellar Evolution, EDP Sciences).

→ continuum; → drive; → wind.

In a → massive star, penetration of the upper layers of the → convective core into the → radiative zone due to → turbulence effects. The enlargement of the convective core results in more luminous stars in theoretical models.

→ convective; → overshooting.

→ convective overshooting.

→ core; → overshooting.

A spiral-shaped density enhancement formed around a star when fast stellar winds collide with slower material. This large-scale wind structure can extend from the stellar surface to possibly several tens of stellar radii. The CIRs can be produced by intensity irregularities at the stellar surface, such as dark and bright spots, magnetic loops and fields, or non-radial pulsations. The surface intensity variations alter the radiative wind acceleration locally, which creates streams of faster and slower wind material. CIRs are responsible for the → discrete absorption components seen in some ultraviolet → resonance lines of → hot stars (S. R. Cranmer & S. P. Owocki, 1996, ApJ 462, 469).

→ corotate; → interaction; → region.

A large glass plate placed at the entrance of a Schmidt telescope to correct for spherical aberration over the large field of view.

→ correct; → plate.

The → mass extinction event that destroyed the dinosaurs and a majority of other species on Earth approximately 65 million years ago. This event is believed to have been the impact of a 10 km-size → asteroid or → comet nucleus and its aftereffects, including a severe → impact winter. The collision would have released the energy equivalent to 100 million megatonnes (teratonnes) of → TNT, i.e. more than 10⁹ times the energy of the atomic bomb dropped on Hiroshima on August 6, 1945. Same as the → Cretaceous-Tertiary event.

→ Cretaceous; → Paleogene; → extinction; → event.