An Etymological Dictionary of Astronomy and Astrophysics
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The abundance of a chemical element exceeding a reference value, in particular compared to that of the Sun.

→ over-; → abundance.

A shallow dish-like crater with irregular, sometimes scalloped rims, on the surface of a planet.

From L. patera "abroad, shallow dish" (used for drinking, primarily in a ritual context).

A sentence or expression which is not only describing a given reality, but actually does or accomplishes something. For example "I now declare you husband and wife" (when uttered by the authorized officiator during a marriage ceremony).

→ performative; → utterance.

Pertaining to, situated in, or constituting the periphery.

Adj. of → periphery.

In a charge-coupled device, the detection of charge collected by the transport register rather than by the image-sensing elements.

→ peripheral; → response.

In optics, the ability to see over large angles of view.

→ peripheral; → vision.

The first 10^-43 seconds of the Universe's existence, when the size of the Universe was roughly the Planck length and during which quantum effects of gravity were significant. Also called Planck epoch. Our understanding of the Planck era is poor because theory which encompasses both quantum mechanics and general relativity is needed to be developed.

→ Planck; → era.

Same as → PG 1159 star.

→ post-; → degenerate; → star.

Worthy to be preferred; more desirable.

→ prefer; → -able.

The temperature in the → solar wind, as derived from the mean kinetic energy of protons: mv²/2 = (3/2)kT_p, where k is → Boltzmann's constant. There are two types of proton temperature: parallel temperature, measured from protons moving parallel to the magnetic field, and perpendicular temperature relating to protons at right angles to the magnetic field. The proton temperature is usually derived using particle detectors on board space probes that determine the velocity → distribution function of the particles from their energies (N. Meyer-Vernet, 2007, Basics of the Solar Wind, Cambridge Univ. Press). See also → electron temperature.

→ proton; → temperature.

A plane figure bounded by four straight lines.

From L. quadrilater(us) "four-sided," from L. quattuor, → four, + → lateral.

A linear → Hermitian operator associated with a physical quantity.

→ quantum; → mechanics; → operator.

The epoch in the history of the Universe, lasting from the → Big Bang until about 400,000 years later, when the temperature had dropped to 10⁹ K and the rate of electron-positron → pair annihilation exceeded the rate of their production, leaving radiation the dominant constituent of the Universe. The radiation era was followed by the → matter era.

→ radiation; → era.

The temperature of a source calculated assuming that it behaves as a → blackbody that radiates with the same intensity at the same frequency. Compared to the → effective temperature, the radiation temperature is measured over a narrow region of the → electromagnetic spectrum.

→ radiation; → temperature.

The acceleration imparted to matter by → radiation pressure.

→ radiative; → acceleration.

The operation of a computer during the actual time that the related physical processes take place so that the results can be used to guide the physical processes.

→ real; → time; → operation.

The era some 380,000 years after the → Big Bang (at a → redshift of about 1,100), when the Universe had cooled sufficiently so that protons and electrons combined to form → neutral hydrogen in a process called → recombination. The temperature was about 3,000 K and the ionization fraction low enough for Universe to become transparent to light. Consequently matter and radiation decouple from one another because no further → scattering of the radiation occurs. The observation of the → cosmic microwave background radiation provides a means of studying the Universe at the recombination era. Also called recombination epoch and → decoupling era.

→ recombination; → era.

1) To produce anew; bring into existence again; to bring new and more vigorous.
2) Biology: To renew or restore (a lost, removed, or injured part).
3) Physics: To restore (a substance) to a favorable state or physical condition.
4) Electronics: To magnify the amplification of, by relaying part of the output circuit power into the input circuit (Dictionary.com).

→ re-; → generate.

1) Act of regenerating; state of being regenerated.
2) Electronics: A feedback process in which energy from the output of an amplifier is fed back to the grid circuit to reinforce the input.
3) Biology: The restoration or new growth by an organism of organs, tissues, etc., that have been lost, removed, or injured (Dictionary.com).

→ re-; → generation.

1) Of, relating to, or characterized by regeneration.
2) Tending to regenerate.

→ re-; → generative.