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

The set of values that a → function is allowed to take (i.e. may possibly come out of a function), as opposed to the → range.

→ co-; → domain.

1) Math.: The set of x values that can go into a function f(x). Compare with → codomain and → range.
2) Ferromagnetism: → magnetic domain.

From M.Fr. domaine "domain, estate," from O.Fr. demaine "lord's estate," from L. dominium "property, dominion," from dominus "master of a household," from domus "house;" cognate with Pers. dam, as below; Gk. domos "house;" O.C.S. domu , Russ. dom "house;" Lith. dimstis "enclosed court, property;" O.E. timber "building, structure"); PIE base *dem-/*dom- "to build."

Daman, from Av. dəmāna- "house," dami "in the house;" cf. Sogd. δmān "house;" Mod.Pers. dam "wealth, means of comfort" (often as dam o dastgâh); "threshold, doorway;" Gilaki dâmana "ceiling;" Sariqoli waδem, Yazghulami wəδem "ceiling;" Skt. dám- "house;" Proto-Iranian *damH- "to build;" Gk. demo "I build;" L. domus "house," as above.

In a → ferroelectric substance, the transition layer between two → domains magnetized in different directions. It is of finite thickness ans has nonuniform → magnetization.

→ domain; → wall.

A scaling relation between the → star formation rate (SFR) in galaxies and the total stellar mass (M_*) of the galaxies. This relation, colloquially called the "galaxy main sequence," extends over several orders of magnitudes in M_* and out to → high redshifts, with a modest scatter of ~ 0.3 dex which includes both intrinsic scatter and measurement uncertainties. The existence of such tight scatter at all observed epochs suggests that most galaxies assembled their stellar mass fairly steadily rather than predominantly in → starburst episodes, implying that → mergers have a sub-dominant contribution to the global star formation history (Wuyts et al., 2011 ApJ 742, 96).

→ galaxy; → main; → sequence.

A → main sequence star whose mass is less than 1.5 Msun. Lower main sequence stars generate their energy chiefly through the → proton-proton chain. The core is surrounded by a → radiative zone above which lies a → convective envelope. In such stars the → opacity at the surface is high because of the low → surface temperature. Therefore, radiation cannot carry all the radiation because of high opacity. Thus, energy transfer takes place by → convection to the outer layer.

→ lower; → main; → sequence.

Any of several microscopic areas in a → ferromagnetic material that possesses a net → magnetic field, because electron spins are aligned in the same direction. In the absence of an external magnetic field, the directions of the magnetization vectors of the separate domains do not coincide and the resultant magnetization of the whole body may be zero.

→ magnetic; → domain.

Chief in size, extent, or importance; leading; → principal.

From M.E. meyn, mayn "strength, power," from O.E. mægen "power, strength, force," from P.Gmc. *maginam- "power," from *mag- "to be able, have power."

Farist, literally "foremost" (cf. Mid.Pers. frahist "main, principal, first, much"), from far-, Mid.Pers. fra-; O.Pers. fra- "forward, forth;" Av. frā "forth," pouruua- "first"; cf. Skt. pūrva- "first," pra- "before, formerly;" Gk. pro; L. pro; O.E. fyrst "foremost," superlative of fore, E. fore + -est superlative suffix, Mid.Pers. -ist, -išt-; Av. -išta-, cf. Skt. -istha-, Gk. -istos, O.H.G. -isto, -osto, O.E. -st, -est, -ost.

Same as → main lobe.

→ main; → beam.

The area between → Mars and → Jupiter where most of the → asteroids in our → solar system are found.

→ main; → belt.

In the n x n → matrix , the entities a₁₁, a₂₂, ..., a_nn.

→ main; → diagonal.

The lobe in the reception pattern of a radio telescope that includes the region of the maximum received power. Also called major lobe and main beam.

→ main; → lobe.

A thin strand of material encircling Jupiter; the main component in → Jupiter's ring system of three parts. The diffuse innermost boundary begins at approximately 123,000 km. The main ring's outer radius is found to be at 128,940 km,

→ main; → ring.

An evolutionary stage in the life of a star when it generates its energy by the conversion of hydrogen to helium via → nuclear fusion in its core. Stars spend 90% of their life on the main sequence. On the → Hertzsprung-Russell diagram it appears as a track running from top left (high temperature, high luminosity, high mass) to lower right (low temperature, low luminosity, low mass). See also → zero age main sequence (ZAMS), → terminal age main sequence (TAMS).

→ main; → sequence.

The method of determining the distance to a star cluster by overlaying its main sequence on the theoretical zero-age main sequence and noting the difference between the cluster's apparent magnitude and the zero-age main sequence's absolute magnitude.

→ main sequence; → fitting.

The point on the → Hertzsprung-Russell diagram of a star cluster at which stars begin to leave the → main sequence and move toward the → red giant branch. The main-sequence turnoff is a measure of age. In general, the older a star cluster, the fainter the main-sequence turnoff. Same as → turnoff point.

→ main sequence; → turnoff.

A star that has evolved off the → main sequence.

→ post-; → main sequence; → star.

A → binary system whose components are → pre-main sequence stars.

→ pre-; → main sequence; → binary.

A → Herbig AeBe star displaying → forbidden emission lines in its spectrum.

→ pre-; → main; → sequence; → B[e] star.

A star that evolves in the → Hayashi phase and has not yet reached the → zero-age main sequence.

→ pre-; → main sequence, → star.

1) To continue in the same state.
2) To stay behind or in the same place.

M.E. remainen, from O.Fr. remain-, stressed stem of remanoir "to stay, dwell, remain," from L. remanere "to remain, to stay behind; be left behind," from → re- "back" + manere "to stay, remain" (from PIE root *men- "to remain," cf. Pers. mân-, mândan, as below.

Mândan "to remain, stay" (mân "house, home;" Mid.Pers. mândan "to remain, stay;" O.Pers. mān- "to remain, dwell;" Av. man- "to remain, dwell; to wait;" Gk. menein "to remain;" L. manere "to stay, abide" (Fr. maison, ménage; E. manor, mansion, permanent); PIE base *men- "to remain, wait for."