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

A particle which cannot be divided into other constituents. More specifically, a particle whose field appears in the fundamental field equations of the unified field theory of elementary particles, in particular in the Lagrangian. For example, the → electron, the → photon, and the → quark are elementary particles, whereas the proton and neutron are not. The elementary nature of a particle can be revised depending on new observations or theories. Also called → fundamental particle.

Elementary, M.E. elementare, from M.F. élémentaire, from L. elementarius, from → element + adj. suffix -arius; → particle.

Bonyâdin, from bonyâd "basis, foundation," variant of bonlâd, from bon "basis; root; foundation; bottom" → element + lâd "root; foundation; reason, cause; wall" + adj. suffix -in.

Electrons and atomic nuclei ejected by solar flares, travelling with velocities amounting to a fraction of the velocity of light, and energies mostly in the range 1-100 million → electronvolts (eV), but occasionally as high as 15 billion eVs. Also known as solar → cosmic rays.

Energetic, from Gk. energetikos, from energe-, → energy, + -tikos a suffix, equivalent in meaning to → -ic, occurring in adjectives; → solar; → particle.

Zarrehâ plural of zarré, → particle; xoršidi, → solar; kâružmand from kâruž, → energy, + -mand possession suffix.

A concept whereby chemical → concentrations among geological or environmental media are at equilibrium, and therefore the partitioning of metals in those media can be predicted based on → partition ratios.

→ equilibrium; → partitioning.

1) General: Equal sharing of the → total energy among all → components of a → system.
2) In the → kinetic theory of gases, the → theorem according to which → molecules in → thermal equilibrium have the same average energy (¹/₂ kT) associated with each independent → degree of freedom of their motion.

→ equi-; → partition.

In quantum field theory, a particle that transfers momentum and energy between interacting objects, and is said to mediate the interaction. All four of the fundamental forces involve the exchange of one or more particles. For example, photon is the exchange particle of the electromagnetic force.

→ exchange, → particle.

An → exoplanet similar to Earth.

→ exo- + → earth.

A sketch or image used to recognize objects in the field of view of a telescope.

Finding, noun of → find; chart, from M.Fr. charte "card, map," from L. charta "leaf of paper, tablet," from Gk. khartes "layer of papyrus."

Negâre-ye yâbeš, from negâré, from negâr "picture, figure" (verb negârdan, negâštan "to paint"), from prefix ne- "down; into," → ni-, + gâr, from kar-, kardan "to do, to make" (Mid.Pers. kardan; O.Pers./Av. kar- "to do, make, build;" Av. kərənaoiti "he makes;" cf. Skt. kr- "to do, to make," krnoti "he makes, he does," karoti "he makes, he does," karma "act, deed;" PIE base k^wer- "to do, to make"); yâbeš, verbal noun of yâftan, → find.

A → lunar phase that occurs in the middle of the interval between the → new Moon and the → full Moon, when half of the Moon's disk is illuminated. At first quarter, the Moon is situated at 90° east of the Sun.

→ first; → quarter.

For a → function with several → variables, the derivative, done only once, with respect to one of the variables. For example ∂u/∂x for u = u(x,y).

→ first; → order; → partial; → derivative.

Same as → elementary particle.

→ fundamental; → particle.

A proposal regarding the initial state of the → Universe prior to the → Planck era. This → no boundary hypothesis assumes an imaginary time in that epoch. In other words, there was no real time before the → Big Bang, and the Universe did not have a beginning. Moreover, this model treats the Universe like a quantum particle, in an attempt to encompass → quantum mechanics and → general relativity; and attributes a → wave function to the Universe. The wave function has a large value for our own Universe, but small, non-zero values for an infinite number of other possible, parallel Universes.

Hartle, J., Hawking, S., 1983, "Wave function of the Universe," Physical Review D 28; → initial; → state.

A band in the → absorption spectrum of → ozone (O₃) extending in the → ultraviolet from 200 nm to 300 nm. It is stronger than the → Huggins band. See also: → Hartley band.

W. N. Hartley, J. Chem. Soc. 39, 111 (1881).

A way of testing the quality of optical systems. In this method, incident rays from a point source are isolated by small holes in an opaque screen located close to the lens or mirror under test. Photographic plates are inserted into the beam within and beyond the focal region. The black dots on the exposed plates, which reveal differences of optical focus in the various zones of the lens or mirror, are analyzed to yield the objective's figure. → Shack-Hartmann wavefront sensor.

Named after the German astronomer Johannes Hartmann (1865-1936), who developed the method. → test.

A unit of energy used in atomic and molecular physics; symbol Ha or E_h. It is defined as: 1 Ha = m_ee⁴/(4ε₀²ħ), where m_e is the mass of electron, e its charge, ε₀ the → permittivity of vacuum, and ħ → reduced Planck's constant. Its value is 2 → rydbergs, or 4.3597 x 10^-18 → joule, or 27.213 → electron-volts.

Named for the British physicist and mathematician Douglas R. Hartree (1897-1958).

1) A hollow muscular organ that pumps the blood through the circulatory system by rhythmic contraction and dilation. In vertebrates there may be up to four chambers (as in humans), with two atria and two ventricles.
2) The heart regarded as the centre of a person's thoughts and emotions, especially love or compassion (OxfordDictionaries.com).

M.E. herte, from O.E. heorte "heart breast, soul, spirit, will, desire; courage; mind, intellect;" cf. O.Saxon herta, O.Frisian herte, O.Norse hjarta, Du. hart, O.H.G. herza, Ger. Herz; cognate with Pers. del, as below; PIE root *kerd- "heart."

Del "heart" (Pashtu z'rrah, zyah; Baluci zirde "heart, mind, soul;" Kurd. zar; Sogd. žyâwar); Mid.Pers. dil; Av. zərəd-; cf. Skt. hrd-; Gk. kardia; L. cor "heart" (Fr. cœur; Sp. corazon, It. cuore); Russ. serdtse; Arm. sirt; E. heart, as above.

1) To give, convey, or grant from or as if from a store.
2) To communicate the knowledge of; disclose.

M.E., from O.Fr. impartir, from L.L. impartire "to share in, divide with another, communicate," from assimilated form of → in- "into, in" + partire "to divide, → part."

Darpârdan, from dar-, → in-, + pâr, → part, Mid.Pers. pârag "part, portion; gift, offering;" Av. pāra- "debt," from par- "to remunerate, equalize; to condemn;" PIE *per- "to sell, hand over, distribute; to assign;" + -dan infinitive suffix.

→ obliquity of the ecliptic.

→ inclination; → Earth; → equator.

A → near-Earth object whose → orbit lies always inside Earth's orbit.

→ inner; → Earth; → object.

An expression of an integer nas the sum of one or more positive integers. The number of different partitions of n is denoted p(n). This function is called the partition function. For example, p(5) = 7, because 5 can be partitioned as: 5 = 5 = 4 + 1 = 3 + 2 = 3 + 1 + 1 = 2 + 2 + 1 = 2 + 1 + 1 + 1 = 1 + 1 + 1 + 1 + 1.

→ partition; → integer.

Fluid mechanics: In the → Lagrangian method, a particle that moves as though it is an element of fluid. The particle concept is an approach to solving complicated fluid dynamics problems by tracking a large number of particles representing the fluid. The particle may be thought of as the location of the center of mass of the fluid element with one or more property values.

→ Lagrangian; → particle.