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

One of the seven stars of the → Big Dipper, which links Ursa Major's tail to the Bear's hindquarters. Megrez is the dimmest of the Big Dipper stars at magnitude +3.3. It is an A3 dwarf, about 20 times more luminous that the Sun, lying 81 light-years away.

From Ar. al-Maghriz(المغرز) "the root, base, bottom" (of the Bear's tail).

A → giant star of → apparent visible magnitude 3.54 in the → Orion constellation. λ Ori is of → spectral type O8 III, has a mass of about 28 → solar masses, a size of about 10 → solar radii, and an → effective temperature of around 35,000 K. Meissa is a → soft X-ray source with a → luminosity of 10³² erg s^-1 and peak emission in the energy range of 0.2-0.3 keV, which is probably generated by the → stellar wind. Meissa is a member of the → Orion OB1 association. It is in fact a → double star with a → companion at an angular separation of 4.41 arcseconds. This fainter component has a magnitude of 5.61, is a → main sequence star of → spectral type B0.5 V. There is an outlying component, Meissa C, which is an F-type main sequence F8 V star. This star in turn may have a very low mass companion that is probably a brown dwarf. λ Ori, excites a fairly symmetric → H II region, Sh2-264 surrounding it. Many observational studies have found dark clouds external to this H II region.

Arabic al-maysan (مَیسان) "bright."

(v.int.) To become liquefied by warmth or heat, as ice, snow, butter, or metal. (v.tr.) To reduce to a liquid state by warmth or heat; to fuse.

M.E. melten, O.E. meltan "become liquid;" cf. O.N. melta "to digest;" Gk. meldein "to melt," L. mollis "soft, mild."

Godâxtan, godâz- "to melt," from Mid.Pers. vitâxtan, vitâcitan "to melt," from Av. vi-taxti- "flowing away, melting," from vi- "apart, away from, out" (O.Pers. viy- "apart, away;" cf. Skt. vi- "apart, asunder, away, out;" L. vitare "to avoid, turn aside") + tak- "to run, to flow," taciāp- "flowing water," tacinti (3pl.pers.act.) "to flow," tacar- "course," tacan "current, streaming;" Mod.Pers. tâz-, tâxtan "to run; to hasten; to assault," tâzi "swift (greyhound)," tak "running, rush;" Mid.Pers. tâz-, tâxtan "to flow, to cause to walk," tc- "to flow, to walk," tag "running, attack," tâzig "swift, fast;" Khotanese ttajs- "to flow, to walk;" cf. Skt. tak- "to rush, to hurry," takti "runs;" O.Ir. tech- "to flow;" Lith. teketi "to walk, to flow;" O.C.S. tešti "to walk, to hurry;" Tokharian B cake "river;" PIE base *tek^w- "to run; to flow."

A severe accident in a nuclear reactor which is caused by a major failure in the reactor cooling circuit leading to the melting of the reactor core. Without coolant, the core would overheat so that the uranium fuel would melt. If the core continued to heat up, the steel walls of the core would also melt. If the molten core escaped from the containment housing of the reactor, large amounts of highly radioactive materials would be released into the atmosphere. The radioactive contamination of the air, water, and soil can have disastrous consequences for life.

→ melt; down, M.E. doun, from O.E. dune "downward," short for adune, ofdune, from a-, of "off, from" + dune "hill."

Forugodâxt, from foru- "down, downward; below; beneath," as in forurixtan, forunešastan, foruraftan (Mid.Pers. frôt "down, downward;" O.Pers. fravata "forward, downward;" cf. Skt. pravát- "a sloping path, the slope of a mountain") + godâxt past stem of godâxtan, godazidan → melt.

The temperature at which a solid changes to a liquid.

→ melting; → point.

A person or a thing that is part of a group body; e.g. a star which belongs to a cluster.

From M.E., from O.Fr. membre, from L. membrum "limb, member of the body, part."

Hamvand, literally "linked, joined together," from ham- "together, with; same, equally, even" (Mid.Pers. ham-, like L. com- and Gk. syn- with neither of which it is cognate. O.Pers./Av. ham-, Skt. sam-; also O.Pers./Av. hama- "one and the same," Skt. sama-, Gk. homos-; originally identical with PIE numeral *sam- "one," from *som-. The Av. ham- appears in various forms: han- (before gutturals, palatals, dentals) and also hem-, hen-) + vand "joined, tied," from bastan, vastan "to bind, shut" (O.Pers./Av. band- "to bind, fetter," banda- "band, tie" (cf. Skt. bandh- "to bind, tie, fasten;" PIE *bhendh- "to bind;" Ger. binden; E. bind).

The state of being a member.

From → member + -ship a native E. suffix of nouns denoting condition, character, office, skill, etc., from M.E., O.E. -scipe; akin to shape.

hamvandi, from hamvand, → member, + -i condition, character suffix.

One of several functions used in the → fuzzification and → defuzzification steps of a → fuzzy logic system to map the → nonfuzzy input values to → fuzzy linguistic terms and vice versa. A membership function is used to quantify a linguistic term.

→ membership; → function.

To commit to memory, learn by heart.

From memor-, → memory, + → -ize.

Barmidan, from barm, → memory; az bar kardan, literally "to do from memory," from az preposition, bar, contraction of barm, kardan "to do, make," → -ize.

1) The faculty of the mind to preserve and recall past sensations, thoughts, knowledge, etc.
2) In computers and recording instruments, any device into which information can be introduced and later extracted.

M.E. memorie, from L. memoria, from memor "mindful, remembering;" cf. Gk. mermera "care," merimna "anxious thought, sorrow," martyr "witness;" Pers. šomârdan "to count;" Mid.Pers. ôšmârtan, ôšmurtan "to reckon, calculate, enumerate, account for;" from Av. base (š)mar- "to have in mind, remember, recall," pati-šmar- "to recall; to long for," hišmar-; Skt. smar- "to remember, become aware," smarati "he remembers."

Barm "memory," variant bar (az bar kardan "to memorize"), bir, vir, from Mid.Pers. varm "memory," variants vir, vârom "mind, conscience;" from Av. vārəma, vārəm "according to one's wishes," from var- "to choose."

The amount of information which can be retained in a memory, usually expressed as the number of words which can be retained. For comparison of different memories this number is expressed in bits.

→ memory; → capacity.

See → periodic table.

→ periodic table.

A → lens with a crescent-shaped section; a → concavo-convex lens.

Mod.L. meniscus, from Gk. meniskos "lunar crescent," diminutive of mene, → moon.

Mâhak, diminutive of mâh, → moon.
Kuž-kâv "convexo-concave," → convex; → concave.

A multiple star of magnitude V = 1.90 which is situated in the → Auriga constellation at 81 → light-years away. Other main designations: HR 2088 and HD 40183. Although the third brightest star of the constellation, it bears "Beta" designation. Menkalinan is composed of two main components, which make up a → spectroscopic binary. The combined apparent magnitude varies over a period of 3.96 days between +1.89 and +1.94, as every 47.5 hours one of the stars partially eclipses the other. Both are metallic-lined → subgiant stars of spectral type A2 IV. Each is about 48 times more luminous than the Sun and has roughly the same mass and radius (2.6 times that of the Sun). There is a third component of magnitude 14.1, which is separated from the main pair by 13'', corresponding to a projected distance of 330 → astronomical units.

From Ar. Al Mankib dhi'l 'Inan (منکب ذی العنان) "the Shoulder of the One Who Holds the Reins," which is the rendition of the Gk. mythology character Auriga (Charioteer).

A → giant star of → apparent visual magnitude +2.06 located in the southern constellation → Centaurus. It has a → spectral type of K0 III and lies 61 → light-years away. Also called Haratan.

Menkent, corruption of Ar. Mankib "shoulder," short for Mankib al-Qanturis (منکب القنطورس ) "shoulder of Centaurus."

The Table Mountain. A faint constellation near the south celestial pole, at 5h right ascension, 80° south declination. It contains part of the → Large Magellanic Cloud, and its brightest star is of magnitude 5.1. Abbreviation Men; genitive Mensae.

First introduced by the French astronomer Nicolas Louis de Lacaille (1713-1762) under the name Mons Mensae, from L. mons "mountain" + mensa "table" to refer to Table Mountain in South Africa. Lacaille made important early observations of the southern sky from the Cape Town region.

Mizkuh, from miz "table," originally "preparations for entertaining a guest; guest;" Mid.Pers. mêzd "offering, meal" + kuh→ mountain.

Of or pertaining to the → mind.

M.E., from M.Fr. mental, from L. mentalis "of the mind," from mens (genitive mentis) "mind," from PIE root *men- "to think."

Menti, mentâl, adjectives of ment, → mind; → -al.

1) Mental capacity or endowment.
2) Mental capacity or endowment (Dictionary.com).

→ mental; → -ity.

1) To refer briefly to; name, specify, or speak of (Dictionary.com).
2) A direct or incidental reference; a mentioning (Dictionary.com).

M.E. mencioun, from O.Fr. mencion "mention, memory, speech," from L. mentionem "a calling to mind, a speaking of," from root of Old L. minisci "to think," related to mens "mind," from PIE root *men- "to think;" cf. Pers. man, mân "thought, to think," → mind.

Ayât, from Mid.Pers. ayât, ayâd "remembrance, recollection, memory;" Mod.Pers. yâd.

A blue → dwarf star of → spectral type A1 with an → apparent magnitude of 2.37 in the constellation → Ursa Major. It lies 79 → light-years away and has a → luminosity almost 60 times solar, and a mass about triple that of the Sun. Although Merak ranks fifth in brightness in the → Big Dipper, it received the Beta designation from Bayer, who lettered the Dipper's stars from front to back.

From Ar. al-Maraqq (المراق) "the soft parts of the belly, the loins."