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

In general, the process of repeatedly adding a quantity to itself a certain number of times, or any other process which has the same result.

Verbal noun of → multiply.

The sign used to indicate multiplication, either a times sign (×), a centered dot (·), or an asterisk. The multiplication sign was introduced by William Oughtred in 1631.

→ multiplication; → sign.

Involving → multiplication.

From multiplicate, → multiply, + → -ive.

The number which when used as the multiplier of another number leaves the second unchanged; one.

→ multiplicative; → identity.

The number which when used as a multiplier of another number (except 0) produces 1. For example (1/5) x 5 = 1; each of the numbers is the multiplicative inverse of the other.

→ multiplicative; → inverse.

1) The state of being multiple, made of several components.
2) In atomic and nuclear physics, the number of → levels into which the energy of an atom, molecule, or nucleus splits as a result of → Russell-Saunders coupling between → orbital angular momentum and → spin angular momentum. It is given by 2S+1, where S is the total electron → spin quantum number. The multiplicity of an energy level is indicated by a left superscript to the value of L, where L is the resultant electron orbital angular momentum of the individual electron orbital angular momenta.
3) In → statistical mechanics, the number of → microstates corresponding to a given → macrostate.

→ multiple; → -ity.

Arithmetic: A number by which another is multiplied. Physics: A device for intensifying some effect.

Agent noun of → multiply.

To make many or manifold; increase the number, quantity, etc., of.
Arithmetic: To find the product of by multiplication.

O.Fr. multiplier, from L. multiplicare "to increase," from multiplex (gen. multiplicis) "having many folds, many times as great in number," from multi- "many" + base of plicare "to lay, fold, twist."

Bastâyidan, from bastâ, → multiple, + -idan infinitive suffix.

An entity consisting of several poles.

→ multi-; → pole.

A variable used in → spherical harmonic expansions. Each spherical harmonic is characterized by its multipole index l: l = 0 for a → monopole, l = 1 for a → dipole, and so on. It is used in particular to describe the → cosmic microwave background anisotropy: ΔT/T₀ (θ,φ) = Σ a_lmY_lm(θ,φ), where θ and φ are the → spherical polar coordinates, Y_lm is the → spherical harmonic functions, and the sum runs over l = 1, 2, ..., ∞ and m = -l, ..., l, where the multipole index l corresponds to angular scales ≅ 180°/l.

→ multipole; → index.

The quantity that gives the electric potential field due to a distribution of charges, such as a → dipole, → quadrupole, → octupole, etc. A multipole moment usually involves powers of the distance to the origin, as well as some angular dependence.

→ multi-; → pole; → moment.

A method in the evaluation of polynomials which involves fewer basic operations and allows simpler computation, especially for polynomials of high degree. More specifically, the polynomial P(x) = a₀ + a₁x + a₂x² + a₃x³ + ... + a_nxⁿ can be written in the nested form as: P(x) = a₀ + x(a₁ + x(a₂ + ... + x(a_{n - 1} + a_nx) ...)). For example, the polynomial P(x) = x³ - 5x² + 10x - 3 has the following nested form: P(x) = ((x - 5)x + 10)x - 3. Same as the → Ruffini-Horner method.

→ nested; → multiplication.

A → multiple star system that lacks the characteristics of a → hierarchical multiple system.

→ non-; → hierarchical; → multiple; → system.

Electronic tube which converts photons into electrons, multiplies the electrons via a series of electrodes, and produces a measurable current from a very small input signal.

→ photo- + → multiplier.

A generalization of the concept of multiplet to the case when there are several quantum numbers that describe the quantum-mechanical states.

→ super-; multiplet.

1) The top, summit, or apex.
2) To tilt or cause to tilt; overturn, upset, or overthrow.

1) M.E. tip, from M.L.G. or M.Du. tip "utmost point, extremity" (cf. Ger. zipfel, a diminutive formation).
2) From, tip noun from tip (v.) "to overturn, upset," from M.E. typen "to upset, overturn."

1) Nok "tip," variant tok.

A technique for deriving extragalactic distances which uses the → luminosity of the brightest → red giant branch stars in old → stellar populations as a → standard candle. For old (> 2-3 Gyr), → metal-poor ([Fe/H] < -0.7) stellar populations, this luminosity is relatively well determined, and the → absolute magnitude of these stars in the I band is roughly constant (M_I = -4.1 ± 0.1).

→ tip; → red giant; → branch; → method.

A rapidly moving → mirror used in → adaptive optics to correct overall movements of the incoming → wavefront of light caused by → atmospheric turbulence. The simplest form of adaptive optics is tip-tilt correction, which corresponds to correction of the tilts of the wavefront in two dimensions. This is done by tipping and tilting the mirror rapidly in response to overall changes in position of a reference star. See also → deformable mirror.

From, tip noun from tip (v.) "to overturn, upset," from M.E. typen "to upset, overturn" + tilt noun from tilt (v.) "to cause to lean, incline, slope, or slant," → tilt; → mirror.

Âyené, → mirror; kaj "turned aside; crooked, bent" (cf. Skt. kubja- "hump-backed, crooked," Pali kujja- "bent," L. gibbus "hump, hunch," Lith. kupra "hump") + -o- "and" + râst→ right + -gar agent noun suffix → -or.