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

A star whose light is not affected by→ interstellar absorption. → reddening

→ un-; → reddened star.

Describing an image whose constituent or elementary parts are not resolved. → unresolved source.

→ un- + → resolved.

A source of radiation whose angular size is too small for details of its structure to be revealed.

→ unresolved; → source.

An image in which finer details are not visible. → blurred image

→ un-; → sharp image.

A process for amplifying fine details in a registered image. Generally speaking, the process consists of creating a mask which contains larger scale features of the image and then subtracting the mask from the initial image.

→ un-; → sharp; → masking.

Not → stable, as in → unstable atom, → unstable equilibrium.

→ un-; → stable.

An atom whose nuclei → decay by → radioactivity.

→ unstable; → atom.

An equilibrium state of a system in which if a small perturbation away from equilibrium is applied, the system will move farther away from equilibrium state. For example, mechanical equilibrium in which the potential energy is a maximum, as a sphere placed on top of a hill. Mathematically, if the second derivative of the energy with respect to the coordinate of interest is negative, the system is in an unstable equilibrium. → stable equilibrium.

→ unstable; → equilibrium.

The brightest star as well as the Alpha star of → Serpens, thus also known as α Serpentis. It is a third magnitude (V = 2.65) an orange giant of spectral type K2 with a radius 15 times as large as that of the Sun and a surface temperature of 4300 kelvins. It is approximately 73.2 light years from Earth. Unukalhai is in fact a triple star system. The second star (α Serpentis B) is 58 arcseconds from the primary and has a magnitude of 11.8. The third star (α Serpentis C), 13th magnitude, lies 2.3 arcminutes from A. Other designations: Cor Serpentis, HR 5854, HD 140573.

From Ar. 'unuq al-hayyah (عنق‌الحیه) "Neck of the Snake," from 'unuq "neck" + al-hayyah "snake."

To, toward, or in a more elevated position.

M.E. up(pe) (adv.), O.E. up(p) "to a higher position;" cf. O.Frisian up, O.S. up, M.Du. up, op, O.N. upp; O.H.G. uf; (Ger. auf), Goth. iup.

Bâlâ "up, above, high, elevated, height" (related to boland "high," borz "height, magnitude" (it occurs also in the name of the mountain chain Alborz), Lori dialect berg "hill, mountain;" Mid.Pers. buland "high;" O.Pers. baršan- "height;" Av. barəz- "high, mount," barezan- "height;" cf. Skt. bhrant- "high;" L. fortis "strong" (Fr. & E. force); O.E. burg, burh "castle, fortified place;" Ger. Burg "castle;" Goth. baurgs "city;" E. burg, borough; Fr. bourgeois, bourgeoisie, faubourg); PIE base *bhergh- "high."

1a) An incline going up in the direction of movement.
1b) An increase or improvement.
1c) A new version, improved model, etc.
2a) To promote to a higher grade or rank.
2b) To improve or enhance the quality or value of (Dictionary.com).

→ up; → grade.

The process by which an area of Earth's crust slowly rises either due to increasing upward force applied from below or decreasing downward force (weight) from above.

From → up + → lift.

Bâlâmad, literally "coming up," from bâlâ, → up, + âmad past stem of âmadan, → come.

To send data from one's computer to another computer. See also: → loading, → download.

→ up-; → load.

Bârgozâštan, literally "to put load," from bâr, → load, + gozâštan "to put, to place," → passage.

Higher, as in place, position, pitch, or in a scale.

Upper, from → up, → hyper-.

Bâlâ, → up; zabarin, → superior.

The part of the → arm between the → shoulder and the → elbow.

→ upper; → arm.

Bâzu "arm," from Mid.Pers. bâzûk "arm;" Av. bāzu- "arm;" Mod.Pers. bâhu "stick, staff; arm;" cf. Skt. bāhu- "arm, forearm;" Gk. pechys "forearm, arm, ell;" O.H.G. buog "shoulder;" Ger. Bug "shoulder;" Du. boeg; O.E. bôg, bôh "shoulder, bough;" E. bough " a branch of a tree;" PIE *bhaghu- "arm").

The general term applied to the atmosphere above the → troposphere.

→ upper; → atmosphere.

Same as → superior culmination.

→ upper; → culmination.

In atomic physics, an initial energy state in an emission transition.

→ upper; → level.

Of an integral operator, the point at which the integration ends.

→ upper; → limit.

A → main sequence star with a mass above 1.5 Msun. Upper main sequence stars have high central temperatures so that they produce their energy through the → CNO cycle. The outward energy flux is very high and therefore this flux cannot be maintained by → radiative transfer. Thus, upper main sequence stars have → convective cores. Outside the core, there is a → radiative zone. The mass of the convective core gradually diminishes as the hydrogen is consumed. The surface hydrogen is fully ionized and the → opacity is due to → electron scattering The opacity due to electron scattering.

→ upper; → main; → sequence.