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

→ convective overshooting.

→ core; → overshooting.

A → profile representing the number density of stars in the → core of a galaxy.

→ core; → profile.

A supernova arising from the → core collapse of a → massive star. Same as → Type Ib, → Type Ic, or → Type II supernova.

→ core; → collapse; → supernova.

A → radio-loud quasar in which the central source is enhanced by → relativistic beaming and characterized by a → flat  → spectrum. It has been conjectured that this phenomenon is an → orientation effect. If a radio-loud quasar is seen along its → jet, it will appear as a core-dominated source. See also → lobe-dominated quasar.

→ core; → dominate; → quasar.

A radio galaxy characterized by an emission "halo" surrounding a more intense "core". About 20% of the known extended radio sources are of the core-halo type.

→ core; → halo; → galaxy.

The → mid-infrared radiation which is scattered by unusually large → dust grains in the denser core regions of → molecular clouds. It occurs between 3 and 5 μm, when the light from nearby stars undergoes → scattering by the grains provided that they are about 1 μm in size, instead of 0.1 μm, as previously thought. Coreshine, which was detected in Spitzer IRAC data, is a widespread astronomical phenomenon. It is found across dozens of → dark clouds in the Galaxy and during all the phases of the → low-mass star formation (Pagani et al. 2010, Science, 329, 1622). See also → cloudshine.

→ core; → shine.

The apparent acceleration corresponding to the → Coriolis force. It is the acceleration which, when added to the acceleration of an object relative to a rotating → reference frame and to its → centrifugal acceleration, gives the acceleration of the object relative to a fixed reference frame. Coriolis acceleration equals 2ω x v, where ω is the → angular velocity of the rotating reference frame and v is the radial velocity of a particle relative to the center of the rotating reference frame.

→ Coriolis effect; → force.

The apparent → deflection of a body in motion with respect to the Earth, as seen by an → observer on the Earth, caused by the → Earth's rotation. Thus, a projectile fired due north from any point on the northern hemisphere will land slightly east of its target (deflection to the right). This involves two factors: 1) the eastward velocity of Earth's surface decreases from the → equator to the → poles, and 2) when an object starts to move north or south without being firmly connected to the ground it maintains its initial eastward speed (conservation of → angular momentum). Hence, an object travelling away from the equator will be heading east faster than the ground and will seem to be forced east. On the other hand, a ball fired in the northern hemisphere toward the equator deflects to the west. As for the southern hemisphere, a ball fired southward will deflect East. The projectile is not subject to this effect only on the equator, when it is thrown in an east-west direction. The Coriolis effect is therefore greater at higher → latitudes and smaller near the equator. This effect is of paramount importance to the large-scale → atmospheric circulation, the development of storms, and the sea-breeze circulation. In low pressure systems, i.e. zones where air ascends, the air is less dense than its surroundings and this creates a center of low atmospheric pressure. Winds blow from areas of high pressure to areas of low pressure, and so the surface winds would tend to blow toward a low pressure center. But, because of the Coriolis effect, they are deflected. In the northern hemisphere they are deflected toward the right, and fail to arrive at the low pressure center, but instead circulate around it → counterclockwise. In the southern hemisphere the circulation around a low pressure center would be → clockwise. Regarding high pressure systems in the northern hemisphere, a general clockwise rotation is created around the center. Same as the → Coriolis force. See also → geostrophic wind, → geostrophic flow.

Named after Gaspard Gustave Coriolis (1792-1843), French engineer and mathematician who first described this effect; → effect.

An apparent, rather than real, force exerted on a body when it moves in a rotating → reference frame. Same as the → Coriolis effect.

→ Coriolis effect; → force.

A quantity defined as f = 2ω.sinθ, where ω is the Earth's → angular velocity, 2π/T, T is the rotation period of the Earth (→ sidereal day), and θ is the → latitude. Also called the → Coriolis parameter. This frequency occurs often in oceanographic studies. If an → iceberg is floating in a frictionless sea, and is given a push and allowed to move freely, it will travel in a circle of radius U/f, where U is the initial speed imparted by the push. This circle is called an inertial circle.

→ Coriolis effect; → frequency.

The → absolute acceleration of a point P, which is moving with respect to a local → reference frame that is also in motion, is equal to the vector sum of:
a) the acceleration P would have if it were fixed to the moving system;
b) the acceleration of P with respect to the local moving system; and
c) a compound supplementary → Coriolis acceleration.

→ Coriolis effect; → theorem.

A combination of two 30° prisms, one of left-handed quartz and the other of right-handed quartz. The prisms are cemented together in order to get a 60° prism. The device will correct for light rotation and will transmit the beam in a straight direction. The Cornu prism has good ultraviolet transmitting qualities and no → double refraction.

→ Cornu's spiral; → prism.

A plane curve whose Cartesian coordinates are given in parametric form by the → Fresnel integrals. Cornu's spiral is an auxiliary tool for calculating the Fresnel integrals. It is particularly used for the calculation of the diffraction of light at the straight edge of a flat screen or at a straight slit. It is characterized by the fact that the angle it makes with the abscissa axis is proportional to the square of the distance along the curve from the origin of coordinates. Cornu's spiral comprises two branches, symmetrical with respect to the origin and winding asymptotically on the points (0.5,0.5) and (-0.5,-0.5) respectively. Also known as the → clothoid or Euler's spiral.

Named after the French physicist Alfred Cornu (1841-1902); → spiral.

A natural outcome of a → theorem.

L.L. corollarium "a deduction, consequence," from L. corollarium, originally "money paid for a garland," hence "gift, gratuity, something extra;" from corolla "small garland," diminutive of → corona.

Pasâné, from pasân "after," from pas "after, afterward; consequently," variant pošt; Mid.Pers. pas "after; behind, before;" O.Pers. pasā "after;" Av. pasca "afterward (of time); then; behind (of space);" cf. Skt. paścā "after, later, behind;" L. post "after, afterward; behind, in the rear;" O.C.S. po "after, behind;" Lith. pas "at, by;" PIE *pos-, *posko-, + nunace suffix -é

1) The outermost atmosphere of the Sun immediately above the → chromosphere, which can be seen during a total Solar eclipse. It consists of hot (1-2 × 10⁶ K), extremely tenuous gas (about 10^-16 g cm^-3) extending for millions of kilometer from the Sun's surface.
2) Meteorology: A set of one or more colored rings of small radii, concentrically surrounding the disk of the Sun, Moon, or other luminary when veiled by a thin cloud.

L. corona "crown, garland," cf. Gk. korone "anything curved, kind of crown."

Tâj "crown," loanword in Arm. tag "crown," tagavor "king," Proto-Iranian *tâgâ-, maybe from PIE base *(s)teg- "to cover" (L. toga "a garment worn by male citizens in ancient Rome;" hurtâj, from hur, → sun, + tâj.

The Southern Crown. A small, faint southern → constellation, also called Corona Austrini. Abbreviation: CrA, genitive: Coronae Australis.

→ corona; L. australis "southern."

The Northern Crown. A small but prominent northern → constellation that lies east of → Arcturus, between → Boötes and → Hercules, and comprises a distinctive arc formed by the stars seven stars. Abbreviation: CrB; genitive: Coronae Borealis.

→ corona; L. borealis "northern."

An instrument which, when used in a telescope, produces an artificial eclipse, permitting the study of the → solar corona without a total eclipse of the Sun. It was invented in 1930 by the French astronomer Bernard Lyot (1897-1952).

From → corona + → -graph.

Of, or relating to → coronagraphy.

→ coronagraphy; → -ic..

A technique used to observe a relatively dim object (like an → exoplanet) lying close to an outshining bright source (such as star). This is done by blocking the bright object, in the same way the → solar corona is observed using a → coronagraph.

→ coronagraph + suffix -y.