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

A theory dealing with heat transport by → turbulence which includes an elementary treatment of → convection. The central idea is that an unbalanced → buoyancy force drives a → convective cell to move through a distance, called the → mixing length, before the cell dissolves and joins the ambient medium. In this theory an adjustable → mixing length parameter  α is used. The theory, originally due to L. Prandtl (1925), was first applied to the Sun by L. Biermann (1932, Z. Astrophys. 5, 117).

→ mixing; → length; → theory.

A process whereby → angular momentum and chemical species are transported from layer to layer within a star. The main mixing processes include: → convection, → overshooting, → rotation, and → turbulence. The extent to which the interiors of stars are mixed strongly influences their evolution, age, chemical content, and the relationship between their internal and surface → chemical abundances.

→ mixing; → process.

Mass of water vapor per mass of dry air; expressed as grams per kilogram. → humidity

→ mixing; → ratio.

An aggregate of two or more substances that are not chemically combined with each other.

M.E., from L. mixtura "a mixing," from mixtus, → mix.

Âmizé, from âmiz present stem of âmixtan, → mix.

A star of visual magnitude 2.3 in the constellation → Ursa Major, which is the second star from the end of the → Big Dipper's handle. It forms a naked-eye double with → Alcor, lying at an angular separation of about 12 minutes of arc. Mizar is resolved into a 14''.4 → binary star (denoted A and B) with a probable period of thousands of years. Mizar A is a nearly equal-mass, → double-lined spectroscopic binary with period 20.54 days and → eccentricity of 0.53. The two components of Mizar A (denoted Aa and Ab) are both about 35 times as luminous as the Sun, and revolve around each other in about 20 days. Similarly, Mizar B is a → spectroscopic binary with a period of 175.57 days and an eccentricity of 0.46. Recent results suggest that Alcor is actually a binary and apparently → gravitationally bound to the Mizar system. This would make the Mizar-Alcor system a probable → sextuplet, lying at about 78 → light-years from Sun and the second closest such multiple known, after → Castor (Mamajek et al., 2010, AJ 139, 919).

Mizar, from Ar. al-Mi'zar (المءزر) "loin cloth, apron, veil."

A unit of → radio flux density, equal to 10^-3 → jansky (Jy).

→ milli-; → jansky (Jy).

A system of stellar → spectral classification. The same as → Morgan-Keenan classification. Also called MKK system, → Yerkes system.

→ Morgan-Keenan classification.

The system of → MKS units.

→ MKS unit; → system.

The international system of units based on the → meter, → kilogram, and → second.

MKS, the initials of → meter, → kilogram, and → second; meter, kilogram, and second; → unit.

1) (adj.) Assisting or intended to assist the → memory.
2) (adj.) Pertaining to → mnemonics or to memory.
3) (n.) Something intended to assist the memory, as a verse or formula. For example, "Oh, Be A Fine Girl, Kiss Me Right Now Sweetheart!" is a mnemonic for the sequence of stellar → spectral types.

From Gk. mnemonikos "of or pertaining to memory," from mnemon "remembering, mindful," from mnasthai "remember," from PIE base *men- "to think;" cf. Pers. man-, -mân, minu, → idea.

Yâdsepâr, stem of Yâdsepârdan "memorize," from yâd "remembrance, recollection, memory" (Mid.Pers. ayâd) + sepârdan, sepor- "to yield, give, hand over" (Mid.Pers. abespâr- "to hand over, entrust;" cf. O.N. spara, O.H.G. sparon, O.E. sparian, E. spare); yâdsepârik, → mnemonics.

Something capable of assisting one's memory. The process or technique of improving the memory.

→ mnemonic; → -ics.

1) Capable of moving or being moved readily.
2) A mobile phone.

From M.Fr. mobile, from L. mobilis "movable, easy to move; loose, not firm," contraction of *movibilis, from movere "to → move."

Miyâvâ verval adj. and agent noun from miyâvidan, → move.

Of or relating to mode, manner, or form.

→ mode; → -al.

The quality or state of being → modal.

→ modal; → -ity.

1) Physics: Any of the distinct patterns of oscillation that a given periodically varying system can have.
2) Math.: In a series of statistical data, the item or value which occurs most frequently. It is a measure of central tendency.

Mode, from Fr. mode, from L. modus "measure, rhythm, song, manner," from PIE base *med- "to measure, limit, judge, advise;" cf. L. meditari "to think or reflect upon, consider;" Av. mad- "to measure out, apportion, allot;" Gk. medein "to rule;" O.E. metan "to measure out."

Tarz "manner, mode," Arabicized as طرز. Tarz may be related to Av. darəsa- "appearance, looking" (huuarə.darəsa- "having the appearance of the sun"), from Av. darəs- "to look;" cf. Skt. darś-, drś- "to see, appear, look, show" darśa- "apperance, look," drśta- "apparent, visible."
Mod, loan from Fr., cognate with Av. mad- "to measure out, apportion, allot," as above.

1a) A mathematical representation of a process, system, or object developed to understand its behavior or to make predictions. The representation always involves certain simplifications and assumptions. See also → theory, → hypothesis.
1b) A mental image of a phenomenon using familiar terms (or images). For example, in the Bohr model the atom is visualized as a nucleus with electrons orbiting around it in a manner similar to the way that planets revolve around the Sun. While this model is use ul in understanding the atom, it is an over-simplified description of a real atom and does not describe/predict all of its attributes (G. Smooth, Lawrence Berkeley Lab website).
2) To make or construct a model of.

M.Fr. modelle (Fr. modèle), from It. modello "a model, mold," from V.L. *modellus, from L. modulus "measure, standard," from modus "manner, measure" (cf. Av. mad-, → mode), PIE *med- + -ulus, → -ula.

1) Model, from Fr. modèle. Tarzâl, from tarz, → mode + -âl, → -al.
2) Model sâxtan, from model + sâxtan, sâzidan "to build, make, fashion; to adapt, adjust, be fit" (from Mid.Pers. sâxtan, sâz-, Manichean Parthian s'c'dn "to prepare, to form;" Av. sak- "to understand, to mark," sâcaya- (causative) "to teach").
Tarzâlidan, from tarzâl + -idan infinitive suffix.

In a theoretical analysis, the solution that does not correctly treat the intervening parameters, or neglects some crucial factors.

→ model. dependence, noun of → dependent.

The simulation of a process, concept, or operation of a system often implemented by a computer program and making use of a mathematical treatment.

Verbal noun of → model

1) Relating or belonging to present and recent time. → modern physics.
2) Of or pertaining to the historical period following the Middle Ages.
3) Of the latest, most advanced kind, or using the most advanced equipment and techniques available.

From M.Fr. moderne, from L.L. modernus, from L. modo "lately, just now," from modo "to the measure," ablative of modus "manner, measure," → mode.

Novin, from now, → new, + -in adj. suffix, as in dirin, pasin, barin, kehin, mehin, behin, zirin, zabarin, pâyin, bâlâyin.

The physics developed since about 1900, which includes Einstein's → relativity theory and → quantum mechanics, as distinguished from → classical physics. Much of modern physics is concerned with the behavior of matter and energy under extreme conditions or on the very small scale.

→ modern; → physics.