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

In a state of movement. → moving cluster; → moving frame.

Verbal adj. of move, → motion.

A group of stars dynamically associated so that they have a common motion with respect to the local standard of rest.

→ moving; → cluster.

A → frame of reference that moves relative to the observer. The moving frame may be → inertial or → non-inertial. See also → rest frame.

→ moving; → frame.

A young → stellar population that shares a common space motion. A moving group remains kinematically distinct within the general field stars at ages < 1 billion years, before being dispersed. As progenitor gas is cleared by OB star winds, and the natal cluster expands, stars with sufficiently high velocities become unbound and form a young, coeval moving group, possibly leaving behind a bound open cluster. Because of their common origin, moving group members have a shared age and composition. The nearest moving group is the → TW Hydrae association.

→ moving; → group.

A model concerned with the distribution in size of → interstellar grains to account for observations of → interstellar extinction from 0.11 μm to 1.0 μm. The → distribution has the form N(a)da ∝ a^-3.5da, where a is the grain radius. It extends from 5 nm to 1 μm for → graphite and over a narrower range for other materials.

MNR, the initials of authors J. S. Mathis, W. Rumpl, and K. H. Nordsiek (1977, ApJ 217, 425), who introduced the mode; → dust; → model.

A → red supergiant star in the → constellation → Cepheus. It is one of the largest and most luminous stars known in the → Milky Way. μ Cephei appears garnet red and is given the → spectral type of M2 Ia. The star may even be the largest star visible to the → naked eye with an estimated radius of 1.15 billion kilometres. If it replaced the Sun, it would extend beyond the orbit of Saturn. Some of its → physical parameters are: mass = 15 Msol; → radius = 1650 Rsol; → luminosity = 60 x 10⁴ Lsol; → effective temperature = 3690 K. Also called Herschel's → Garnet star.

Cephei, genitive of → Cepheus.

The → sterile offspring of a female horse and a male donkey.

M.E., from O.E. mul, from O.Fr. mul "mule, hinny," from L. mulus "a mule," probably from a pre-Latin Mediterranean language.

Astar, from Mid.Pers. astar, ultimately from *asa-tara-, literally "horse related," from *asa- variant of aspa-, → horse, + -tara- a suffix of relation and comparative adjectives; cf. Skt. asvátara- "mule."

A combining form meaning "many, much, multiple, many times, more than one, more than two, composed of many like parts, in many respects."

From L. multus "much, many," from PIE base *mel- "strong, great, numerous;" cf. L. melior "better," Gk. mala "very, very much."

Bas-, from bas "many, much;" Mid.Pers. vas "many, much;" O.Pers. vasiy "at will, greatly, utterly;" Av. varəmi "I wish," vasô, vasə "at one's pleasure or will," from vas- "to will, desire, wish."

A technique of spectroscopy using fiber optics whereby several objects distributed over the field of view can be observed simultaneously.

→ multi-; → object; → spectroscopy.

Of an approach or study that juxtaposes disciplinary perspectives, adding breadth and available knowledge, information, and methods. The involved disciplines speak as separate voices in encyclopedic alignment. The status quo is not interrogated, and disciplinary elements retain their original identity. See also → interdisciplinary and → transdisciplinary (Thompson Klein, J. 2010, Creating Interdisciplinary Campus Culture, John Wiley and Sons, Inc.).

→ multi-; → disciplinary.

A stellar system with more than one orbiting planet.

→ multi-; → planet; → system.

Consisting of, having, or involving several or many individuals, parts, elements, etc.
Math.: A number that contains another number an integral number of times without a remainder: 25 is a multiple of 5.

From Fr. multiple, from L.L. multiplus "manifold," from L. → multi- "many, much" + -plus "fold," from base of plicare "to fold, twist."

Bastâ-, from bas "many, much" (Mid.Pers. vas "many, much;" O.Pers. vasiy "at will, greatly, utterly;" Av. varəmi "I wish," vasô, vasə "at one's pleasure or will," from vas- "to will, desire, wish") + tâ "fold, plait, ply; piece, part," also a multiplicative suffix; Mid.Pers. tâg "piece, part."

The division of a relatively long exposure into several successive shorter ones, e.g. to avoid detector saturation.

→ multiple; → exposure.

A series of successive integrations in which the integral operator acts on the result of preceding integration.

→ multiple; → integral.

A process of → radiative transfer in which more than one → scattering event may be of importance before → transmission, → reflection, or → absorption. In → radiation-driven winds photon scattering can take place in different → spectral lines. Each scattering occurs in a different spectral line, and successive scatterings occur at lower energies (longer wavelength). The standard theory of line driving (→ CAK model) assumes that photons can be scattered only once in the wind, which is a reasonable assumption for normal → O stars. In → Wolf-Rayet stars, where photons evolve in an atmosphere with a strong → ionization stratification, multiple scattering is important. Indeed the strength of W-R winds appears to exceed the single scattering limit.

→ multiple; → scattering.

A star which appears single but is in fact composed of more than two components. See also → multiple star system; → binary star; → triple star.

→ multiple; → star.

A stellar system composed of several stars bound together by gravitational attraction and revolving around a common center of mass.

→ multiple; → star; → system.

1) A system consisting of several → components.
2) → multiple star system.

→ multiple; → system.

A group of spectral lines arising from transitions having a common lower energy level.

From → multi- + -plet on the model of triplet.

Bastâyé, from bastâ-→ multi- + euphonic -yé, from -é nuance suffix.

A number to be multiplied by another.

From L. multiplicandum, from multiplicandus "to be multiplied," gerundive of multiplicare, → multiply.

Bastâšow, literally "that undergoes multiplication," from bastâ, → multiple, + šow, present stem and agent noun of šodan "to become, to be, to be doing, to go, to pass," from Mid.Pers. šudan, šaw- "to go;" Av. šiyav-, š(ii)auu- "to move, go," šiyavati "goes," šyaoθna- "activity; action; doing, working;" O.Pers. šiyav- "to go forth, set," ašiyavam "I set forth;" cf. Skt. cyu- "to move to and fro, shake about; to stir," cyávate "stirs himself, goes;" Gk. kinein "to move;" Goth. haitan "call, be called;" O.E. hatan "command, call;" PIE base *kei- "to move to and fro."