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

An → adaptive optics instrument used on the → European Southern Observatory (ESO) 3.6-m telescope at La Silla. It was an upgraded version of COME-ON-PLUS, the → Very Large Telescope (VLT) adaptive optics prototype. It had 52 → actuators and performed corrections of the mirror 200 times per second. The reference → wavefront was sensed in the → visible. The observation was done in the → near-infrared (1-5 μm).

→ adaptive; → optics; → near-infrared; → system.

Any of the metallic chemical elements belonging to group 2 of the → periodic table; i.e. → beryllium, → magnesium, → calcium, → strontium, → barium, and → radium. They are not found free in the nature because they are highly reactive.

→ alkaline; → earth; → metal.

Felez, → metal; qalyâyi, → alkaline; xâki "of or pertaining to soil," from xâk, → soil.

Anomalistic from → anomaly.

Pirâhuri from pirâhur, → perihelion.

1) Come into sight; become visible or noticeable.
2) To have the appearance of being; seem.

From M.E. apperen, aperen, from O.Fr. aparoir, aperer, from L. apparere, from → ad- + prarere "to come forth, become visible."

Padidâr šodan, literally "become apparent," from padidâr, → apparent, + šodan, → become.

The period taken for the right ascension of the mean Sun to increase by 24 hours. The starting point is when the mean Sun's longitude is 280°, corresponding roughly to January 1. It is virtually the same as the tropical year.

→ Besselian; → year.

The time interval between the new year's day in a given calendar system and the day before the following new year's day. In the Gregorian system the calendar year begins on January 1 and ends on December 31. In the Iranian calendar it begins on Farvardin 1, the day closest to the spring equinox and ends on Esfand 29 or 30.

→ calendar; → year.

Situated around a → nucleus, as of a → circumnuclear disk.

→ circum- + → nuclear.

A thick disk of gas and dust clouds surrounding the → Galactic Center up to about 20 → light-years. The disk is very clumpy; the → clumps have densities of several 10⁵ particles/cm³, radii of about 0.3 light-years, and gas temperatures above 100 K. The hydrogen mass of the disk is a few 10⁴ → solar masses. Such circumnuclear disks are present also in other galaxies.

→ circumnuclear; → disk.

1) Free from darkness, obscurity, or cloudiness.
2) Transparent; pellucid.
3) Without discoloration, defect, or blemish (Dictionary.com). → clear night.

M.E. clere, from O.Fr. cler, from L. clarus "clear, bright, distinct."

Runé, from Kurd. (Sorani) rûn "bright, clear," rûn kirdin "to explain," variant of rowšan, → bright.

A night sky without clouds, mist, or haze, atmospheric dust particles, and without city lights in which a sixth magnitude star is visible by naked-eye.

→ clear; → night.

Lying on the same straight line. Collinear points are a set of points on the same line.

→ com- + → linear.

A system of two or more forces that lie along the same → line of action.

→ collinear; → force.

A mathematical property where all points lying on a line initially still lie on a line after transformation.

→ collinear; → -ity.

A calendar year which is not a → leap year. In the → Gregorian calendar, a year with 365 days divided into 12 → months, and only 28 days in February. In the → Iranian calendar, a year consisting of 365 days with 12 months, and only 29 days in the month of Esfand.

→ common; → year.

The distortion of images of distant galaxies due to → weak gravitational lensing by → large-scale structures in the → Universe (see, e.g., Kilbinger, M., 2015, arXiv:1411.0115).

→ cosmic; → shear.

Consisting of, represented by, or bound by curved lines. → rectilinear.

From → curve + → linear.

The vertebrate organ of hearing, which is also responsible for maintaining equilibrium. It is usually composed of three parts: the outer ear, middle ear, and inner ear.

M.E. ere, O.E. eare "ear" (O.N. eyra, Dan. øre, M.Du. ore, Du. oor, O.H.G. ora, Ger. Ohr); cf. Gk. aus; L. auris; Av. usi "both ears;" Lith. ausis; O.C.S. ucho; O.Ir. au; PIE *ous-.

Guš "ear" (gušidan "to hear," niyušidan "to listen"); Mid.Pers. gôš "ear," gôšidan "to hear, listen;" O.Pers. gauša-; Av. gaoša- "ear," gaoš- "to hear;" cf. Skt. ghosa- "noise, tumult," ghus- "to sound, cry or proclaim aloud;" PIE *ghous-.

Occurring at or near the beginning of a period of time, process, or sequence of events.

M.E. erlich (adj.), erliche (adv.); O.E. ærlice, from ær "soon, ere" (from P.Gmc. *airiz, from PIE *āier- "day, morning," cf. Av. ayar- "day, day time," ayarə.drājah- "duration of one day," ayarə.bara- "day's ride," Mid/Mod.Pers. parēr "the day before yesterday," from *parā.ayer- "the day before") + -lice "-ly," adverbial suffix.

Âqâzin adj. of âqâz "beginning," from Proto-Iranian *āgaHz-, from prefix ā- + *gaHz- "to run, start," cf. Sogdian āγāz "beginning, start" (Cheung 2007).

A fairly long-lived step in the evolution of → low-mass and → intermediate-mass stars when helium burning shifts from the center to a shell around the core. At this phase the stellar luminosity is provided almost entirely by → helium shell burning. The He-shell burning generally adds mass to the growing carbon/oxygen core, resulting in → degenerate matter due to its increasing density.

→ early; → AGB; → phase.

A period in the evolution of the → solar system when the planets and satellites were in the process of formation.

→ early; → solar; → system.