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

An open-source, one-dimensional astrophysical code which is capable of calculating the evolution of stars in a wide range of environments. It works according to the → Henyey method and uses many modules that deal with various aspects of the theoretical models, such as the → equation of state (EOS), → nuclear reaction networks, → chemical composition, micro-physics, or macro-physics. The EOS and corresponding opacities or nuclear networks are provided in tabulated formats and can be selected by the user, while the micro-physics and macro-physics can be controlled by inlists of relevant parameters and settings (Paxton et al. 2015, ApJS 220, 15 and references therein).

→ module; → experiment; → stellar; → astrophysics.

A hypothetical, large molecular sphere, as a component of the → stellar atmosphere, suggested to encompass → red giant and → supergiant stars. This suggestion has offered satisfactory explanations to the spectrum of → Mu Cephei (Tsuji 2003), but it is not clear whether MOLspheres are common features of the atmospheres of all such stars.

MOL, from → molecular; → sphere.

A → morphismf : Y → X if, for any two morphisms u,v : Z → Y, f u = f v  implies that u =v.

→ mono-; → morphism.

A → mapping between two → objects in a → category.

→ morphology; → -ism.

From rixt, → morphology, + -mandi, → ism.

Of or relating to → morphology. Same as morphological

→ morphology; → -ic.

Of or relating to → morphology. Same as morphological

→ morphologic; → -al.

A classification scheme of galaxies based on their apparent shape. → Hubble classification.

→ morphological; → classification.

1) The study of the form or → structure of anything.
2) The → form and structure of a whole entity under study.
3) Linguistics: The structure of → words in a → language, including patterns of → inflections and → derivation. The study and description of such structures.

From Gk. morphe "form, shape, outward appearance" + → -logy.

Rixt "shape, the way something is cast, as in founding," past stem of rixtan "to cast; to pour; to flow" (Mid.Pers. rēxtan and rēcitan "to flow;" Av. raēk- "to leave, set free; to yield, transfer," infinitive *ricyā; Mod.Pers; rig in morderig "heritage" (literally, "left by the dead"); cf. Skt. rinakti "he leaves," riti- "stream; motion, course;" L. rivus "stream, brook;" Old Church Slavic rēka "river;" Rus. reka "river;" Goth. rinnan "run, flow," rinno "brook;" O.E. ridh "stream." šenâsi, → -logy.

An observationally determined relationship between the → morphological classification of galaxies and the → environments in which they are located. Specifically, the morphology-density relation indicates that early-type galaxies (→ ETG) are preferentially located in high density environments, whereas late-type galaxies (→ LTG) are preferentially found in low density environments. Hence, spiral galaxies are rare in the high densities of clusters and are common in the lower density group environments. Early-type galaxies, on the other hand, are common in clusters and are rarely found in isolation.

→ morphology; → density; → relation.

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.

Photometry using narrow-band filters to isolate a particular spectroscopic line or molecular band.

→ narrow band; → photometry.

The branch of meteorology that deals with clouds.

From Gk. nephos "cloud," nephele "cloud;" cognate with Pers. nam "moisture;" Av. napta- "moist," nabās-cā- "cloud," nabah- "sky;" L. nebula "mist," nimbus "rainstorm, rain cloud;" Skt. nábhas- "moisture, cloud, mist;" O.H.G. nebul; Ger. Nebel "fog;" O.E. nifol "dark;" PIE base *nebh- "cloud, vapor, fog, moist, sky" + → -logy.

Abršenâsi, from abr "cloud," from Mid.Pers. awr, abr (Laki owr, Baluchi haur, Kurd. Soriani hewr); Av. awra- "rain cloud, rain;" cf. Skt. abhra-"thunder cloud;" Gk. afros "scum, foam;" L. imber "rain;" also Sk. ambha- "water;" Gk. ombros "rain," PIE *mbhros "rain cloud, rain," from *mbh- + -šenâsi→ -logy.

A method for finding roots of a → polynomial that makes explicit use of the → derivative of the function. It uses → iteration to continually improve the accuracy of the estimated root. If f(x) has a → simple root near x_n then a closer estimate to the root is x_n + 1 where x_n + 1 = x_n - f(x_n)/f'(x_n). The iteration begins with an initial estimate of the root, x₀, and continues to find x₁, x₂, . . . until a suitably accurate estimate of the position of the root is obtained. Also called → Newton's method.

→ Newton found the method in 1671, but it was not actually published until 1736; Joseph Raphson (1648-1715), English mathematician, independently published the method in 1690.

The half of the → Earth or another → astronomical object between the → north pole and the → equator.

→ northern; → hemisphere.

The branch of physics which is concerned with the study of atomic nuclei, subatomic particles, and their exploitation.

→ nuclear; → physics.

An ellipsoid produced by rotating an ellipse through 360° about its minor axis. Compare with → prolate spheroid.

→ oblate; → spheroid.

The celestial sphere when the circles parallel to the equator are cut obliquely by the horizon plane, which divides them into two unequal parts. In other words, the sphere when its axis is oblique to the horizon of the place.

→ oblique; → sphere.

That part of astrophysics that is mainly concerned with the collection of observational data, in comparison with theoretical astrophysics

→ observational; → astrophysics.

The study of the ocean, embracing and integrating all knowledge pertaining to the ocean's physical boundaries, the chemistry and physics of sea water, and marine biology.

→ ocean + → -graphy.

Oqyânus→ ocean + -šenâsi→ -logy.

A small satellite of → Uranus, the second nearest to the planet, discovered from the images taken by the Voyager 2 spacecraft in 1986. Also denoted Uranus II, it has a diameter of 32 km. Ophelia is one of the two → shepherd moons that keep the planet's Epsilon ring, the other being → Cordelia.

Ophelia is the daughter of Polonius in Shakespeare's Hamlet.