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

Of partial differential equations, the solution which can be obtained from the general solution by particular choice of the arbitrary functions. → general solution; → singular solution.

→ particular; → solution.

1a) A division into or distribution in portions or shares.
1b) A separation; something that separates or divides; a part, division, or section.
2a) The act or process of dividing something into parts. The state of being so divided.
2b) Math.: → integer partition; → set partition.
2c) Computers: → disk partition.
3) To divide into parts or portions. To divide or separate by a partition.

M.E., from O.Fr. particion, from L. partition- "division, partition, distribution," from p.p. stem of partire "to part, divide," from PIE root *per- "to grant, allot," related to → part and akin to pake, as below.

Parke, from Kermâni parke "piece, part, fragmant," related to pâr "→ part;" parkidan, infinitive from parke; parkeš, verbal noun of parkidan.

See → integer partition.

→ partition; → function.

The ratio of the → concentration of a → solute in a single definite form in the stationary phase to its concentration in the same form in the other phase at equilibrium.

→ partition; → ratio.

A chemical separation process whereby a solute is distributed between two phases.

→ partition; → -ing.

The act or fact of being partitioned.

→ partition; → -ment.

In particle physics, a constituent of the hadron originally postulated in the theoretical analysis of high-energy scattering of particles off hadrons. In modern usage, the term parton is often used to mean a quark or a gluon.

Coined by the American physicist Richard Feynman (1918-1988), from part, from → particle + → -ion

A fraction of a whole number in units of 1/1000,000. It is usually used to describe chemical concentrations, very small amounts of pollutants in air, water, body fluids, and uncertainty. For example 30 ppm is 3 x 10^-5 or 0.003%.

→ part; → per; → million.

An electronic component which contains no source of power, in contrast to active components.

→ passive; → component.

A quantum mechanical principle according to which no two identical → fermions can share the same → quantum state. Also known as → exclusion principle.

In honor of Wolfgang Pauli (1900-1958), Austrian theoretical physicist, who formulated the principle in 1925; → exclusion; → principle.

A planet formation concept that concerns the → accretion of small objects of negligible gravitational mass (ranging from centimeters up to meters in diameter) onto large, gravitating bodies: → planetesimals, → protoplanets, or → planets. In a more narrow sense, pebble accretion is an accretion process where (gas) drag and gravity play major roles. Simply put, this means that the pebble has to be aerodynamically small and the planet to be gravitationally large (C. W. Ormel, in Formation, Evolution, and Dynamics of Young Solar Systems, p. 197, eds. M. Pessah, O. Gressel, Springer, 2017).

→ pebble; → accretion.

1) The true motion of a star with respect to the Local Standard of Rest. → proper motion.
2) The motion of a cosmological object other than the apparent recession caused by the expansion of the Universe.

→ peculiar; → motion.

1) Depreciation; a lessening in worth, quality, etc.
2) Semantic change in a word to a lower, less approved, or less respectable meaning.

Verbal noun of → pejorate.

Any plant of the genus Paeonia, having showy, pink, red, or white, globular flowers. Originally cultivated in the temperate regions of Asia, China, Europe, and the northwest parts of North America.

M.E., from M. Fr. peonie, pioiné, from L.L. peonia, from L. pæonia, from Gk. paionia, perhaps from Paion, physician of the gods. The plant was recognized to possess many remedial properties, and was thus given an association with the gods.

Payoniyâ, loan from Gk, as above.

A peony-shaped nebula around the → Wolf-Rayet star WR 102ka as shown by the → Spitzer Space Telescope image at 24 μm. The formation of this infrared bright nebula is attributed to the recent evolutionary history of WR 102ka during → LBV-type eruptions and/or its strong → stellar wind (see, e.g., A. Barniske et al. 2008, A&A 486, 971).

→ peony; → star.

The process of recognizing or identifying something. Usually employed of sense perception, when the thing which we recognize or identify is the object affecting a sense organ.

Verbal noun of → perceive.

The state or quality of being or becoming perfect.

→ perfect; → -tion.

1) Any of various doctrines holding that religious, moral, social, or political perfection is attainable.
2) A personal standard, attitude, or philosophy that demands perfection and rejects anything less (Dictionary.com).

→ perfection; → -ism.

1) A person who adheres to or believes in → perfectionism.
2) A person who demands perfection of himself, herself, or others (Dictionary.com).

→ perfection; → -ist.

In a binary system, the point in the orbit where a component is nearest the other component; opposite of → apastron.

→ peri- + astron; → astro-.