An Etymological Dictionary of Astronomy and Astrophysics
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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 → 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.

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."

NASA's satellite, designed to measure the diffuse infrared and → cosmic microwave background radiation from the early → Universe. It was launched on November 18, 1989 and carried three instruments: DIRBE (the Diffuse InfraRed Experiment), DMR (Differential Microwave Radiometers), and FIRAS (Far-InfraRed Absolute Spectrophotometer). The COBE observations showed that the cosmic microwave background spectrum matches that of a → blackbody of temperature 2.725 ± 0.002 K. COBE also found anisotropies in the cosmic microwave background at a level of a part in 100,000 (→ cosmic microwave background anisotropy). These tiny variations in the intensity of the CMB over the sky show how matter and energy was distributed when the Universe was still very young. Later, through a process still poorly understood, the early structures developed into galaxies, galaxy clusters, and the large scale structure that we see in the Universe today. Two of COBE's principal investigators, George Smoot and John Mather, received the Nobel Prize in Physics in 2006 for their work on the project.

→ cosmic; → background; → explorer.

An opaque region of a → molecular cloud (A_V  10 mag) which is considered to be the progenitor of → star formation. Dense cores have temperatures of about 10 K and masses of roughly 1 to 10Msun each and in which the → molecular hydrogen density is roughly 10⁴-10⁵ cm^-3 and size 0.1 pc. The → self-gravity of a dense core plays a central part in star formation. See also → hot molecular core.

→ dense; → core.

→ core mass function.

→ dense; → core; → mass; → function.

Same as → Gauss's theorem.

→ divergence; → theorem.

The innermost part of the Earth consisting of a solid → inner core, mainly composed of → iron, and a → liquid → outer core. The → pressure and → temperature are so extreme that the molten iron solidifies. The temperature at the inner core boundary is expected to be close to the → melting point of iron at 330 gigapascal (GPa). From static laser-heated diamond anvil cell experiments up to 200 GPa, using synchrotron-based fast → X-ray diffraction as a primary melting diagnostic, S. Anzellini et al. (2013, Science 340, 484) conclude that the melting temperature of iron at the inner core boundary is 6230 ± 500 K. This estimation favors a high heat flux at the core-mantle boundary with a possible partial melting of the → mantle. The inner core, 2,400 km in diameter, is suspended in the molten metal of the → outer core, which is about 2,240 km thick. The temperature difference between the mantle and the core is the main engine for large-scale thermal movements, which coupled with the → Earth's rotation, function as a generator for the planet's → magnetic field.

→ Earth; → core.

Math: A theorem that asserts the existence of at least one object, such as the → solution to a → problem or → equation.

→ existence; → theorem.

1) To travel to or in a place for the purpose of discovery.
2) To make a careful investigation or study of something.

From L. explorare "investigate, search out;" said to be originally a hunters' term meaning "set up a loud cry," from → ex- "out" + plorare "to cry."

Puyidan, originally "to run, trot; wander," from Mid.Pers. pôy-, pwd- "to run;" cf. Gk. speudein "to hasten;" Lith. spudinti.

A person or thing that explores.

Agent noun of → explore.

In → number theory, the statement that for all → integers, the equation xⁿ + yⁿ = zⁿ has no solution in → positive integer. After 358 years of effort by mathematicians to prove the theorem, a complete proof was found by Andrew Wiles in 1995.

→ Fermat's principle; → last; → theorem.

A first object in → hydrostatic equilibrium predicted to form during early dynamical contraction of a → molecular cloud → clump in the course of the → first collapse.

→ first; → core.

A type of → luminescence in which photons of lower energy are emitted as the result of absorption of energy by an atom or molecule from other radiation. The phenomenon lasts as long as the stimulus responsible for it is present.

Coined by English mathematician and physicist Sir George G. Stokes (1819-1903) from fluor-, from → fluorspar, + → -escence, a suffix of nouns denoting action or process, change, state or condition, etc.

Possessing the property of → fluorescence.

→ fluorescence; → -escent.

A tubular → electric discharge lamp in which light is produced by the → fluorescence → phosphors coating the inside of the tube.

→ fluorescent; → lamp.