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

To express in precise → form; state definitely or systematically. To reduce to or express in a → formula.

Verbal form of → form.

A plate of optical material whose thickness is such that the phase difference between the extraordinary and ordinary rays after passing through the place is exactly one-half cycle. It can serve to rotate the plane of polarization of a light beam.

→ half; → wave; → plate.

The front, bony part of the roof of the mouth. → soft palate.

→ hard; → palate.

To become inflated; to increase, especially suddenly and substantially. → inflation, → inflatory model.

Inflate, from L. inflatus p.p. of inflare "to blow into, puff up," from → in- "into" + flare "to blow."

Pandâmidan "to swell," from pandâm [Mo'in] "swelling;" Borujerdi panâm, panam "swellig;" Malâyeri panomidan "to swell;" Laki penamiyen "to swell;" Hamadâni pandumidan "swelling of the eye or other parts of the body;" Kermâni padum kerdan "to swell," padum "swelled; fat, corpulent;" Tâleši pandâm, pandom "swelling;" Gilaki pandâm kudan "rising of river water caused by flood;" cf. Gk. pneuma "wind; breath," from pnein "to blow; to breathe;" PIE base *pneu- "to breathe." Related terms in other Indo-European languages: O.E. fnaeran "to breathe heavily," fneosan "to snort, sneeze;" M.H.G. pfnusen, pfnehen "to breathe, pant, sniff, snort, sneeze;" Norw. fnysa "to breeze;" M.Du. fniesen, Du. fniezen "to sneeze;" O.H.G. niosan, Ger. niesen "to sneeze."

To cover or to separate from conducting bodies by means of nonconductors so as to prevent or reduce the passage, transfer, or leakage of heat, electricity, or sound. → insulation, → insulator.

From L. insulatus "made into an island," from L. insula "island."

From âyeq, → insulator, + kardan "to do," → -or.

To insert (an extra day, month, etc.) in the calendar to make it follow the seasons or moon phases.

From L. intercalatus p.p. of intercalare "to proclaim the insertion of an intercalary day or month," from → inter- + calare "to proclaim, announce solemnly;" → calendar.

Andarhelidan, andarheštan "to insert," from andar-→ inter- + helidan, heštan "to place, put" from Mid.Pers. hištan, hilidan "to let, set, leave, abandon," Parthian Mid.Pers. hyrz; O.Pers. hard- "to send forth," ava.hard- "to abandon;" Av. harəz- "to discharge, send out; to filter;" hərəzaiti "releases, shoots;" cf. Skt. srj- "to let go or fly, throw, cast, emit, put forth;" Pali sajati "to let loose, send forth."

To set or place apart; detach or separate so as to be alone.
Chemistry: To obtain a substance in an uncombined or pure state.
Physics: → isolated system.

Isolate, back-formation from isolated, from Fr. isolé "isolated," from It. isolato, from L. insulatus "made into an island," from insula "island;" maybe from *en-salos "in the sea," from salum "sea."

Vâyutidan, from vâ- denoting "separation" (also "reversal, opposition; repetition; back, backward," variant of bâz-, from Mid.Pers. abâz-, apâc-; O.Pers. apa- [pref.] "away, from;" Av. apa- [pref.] "away, from," apaš [adv.] "toward the back;" cf. Skt. ápāñc "situated behind") + Mid.Pers. yut "separate, different," Mod.Pers. jodâ "separate, apart;" Av. yuta- "separate, apart" + -idan infinitive suffix.

Set apart or separated from others or other things.

Past participle of → isolate.

A galaxy that is not a member of a dense aggregate. In other words, a galaxy that is formed in a low galactic density environment and has evolved without major interactions with other galaxies of similar mass.

→ isolated; → galaxy.

Massive star formation outside → OB associations. Recent observational findings suggest that → massive star formation is a collective process. In other words, massive stars form in → cluster environments and the mass of the most massive star in a cluster is correlated with the mass of the cluster itself. Nevertheless, other observational results give grounds for supposing that massive stars do not necessarily form in clusters but that they can be formed as isolated stars or in very small groups. According to statistical studies nearly 95% of Galactic → O star population is located in clusters or OB associations. This means that a small percentage, about 5%, of high mass stars may form in isolation. Isolation is meant not traceable to an origin in an OB association. This definition therefore excludes → runaway massive stars, which are thought to result from either dynamical interaction in massive dense clusters, or via a kick from a → supernova explosion in a → binary system. Alternatively, isolated massive star has been defined as follows: An O-type star belonging to a cluster whose total mass is < 100 Msun and moreover is devoid of → B stars (Selier et al. 2011, A&A 529, A40 and references therein).

→ isolated; → massive star; → formation.

A → neutron star which does not belong to a → binary system, does not have radio emission, and is not surrounded by a progenitor → supernova remnant. INSs appear to be thermally cooling with no emission outside the → soft X-ray band, except for faint optical/UV counterparts. Although these properties are similar to those of → compact central object (CCO)s, they are a distinct class because they lack any observable associated supernova remnant or nebula. There are presently seven confirmed INSs (sometimes referred to as The Magnificent Seven), six of which have measured weakly modulated X-ray pulsations with periods between 3 s and 11 s, much longer than those of CCOs (A. K. Harding, 2013, Front. Phys. 8, 679).

→ isolated; → neutron; → star.

Thermodynamics: A system which has no exchange of energy or matter with surroundings. The internal energy of such a system remains constant. → closed system; → open system.

→ isolated; → system.

A transformation whose only final result is to transform into work heat extracted from a source which is at the same temperature is impossible. Kelvin's postulate is a statement of the → second law of thermodynamics and is equivalent to → Clausius's postulate.

→ kelvin; → postulate.

1) Happening or arriving after an expected or arranged time; not on time, beyond usual time.
2) Belonging to an advanced stage or period in the development of something. → Late Heavy Bombardment, → late helium flash, → late thermal pulse, → late-type galaxy, → late-type star.

M.E., from O.E. læt "slow, late;" cf. Ger. lass "slothful;" O.N. latr, Goth. lats "slow, lazy;" L. lassus "tired, faint;" Gk. ledein "to be weary."

Dir "late; tardily, slowly; a long while; old, antique," from Mid.Pers. dêr, variants dagr, drâz "long" (Mod.Pers. derâz "long," variant Laki, Kurdi derež); O.Pers. darga- "long;" Av. darəga-, darəγa- "long," drājištəm "longest;" cf. Skt. dirghá- "long (in space and time);" L. longus "long;" Gk. dolikhos "elongated;" O.H.G., Ger. lang; Goth. laggs "long;" PIE base *dlonghos- "long."
Dirân, adjective, variant of dir, as above.

A cataclysmic event in the history of the → solar system, estimated to have occurred 3.9 billion years ago (about 600 million years after the formation of the → terrestrial planets) during which → asteroid and → comet impacts with Earth were some 20,000 times more frequent than today. It is estimated that during this period the terrestrial planets were bombarded with an object 1 km in size every 20 years. This hypothetical event lasted 50 to 150 million years. Several explanations have been put forward, among which the occurrence of an instability in the outer solar system which caused → orbital migration of small bodies from the → Kuiper belt inward.

→ late, with respect to the formation time of the planets; → heavy; bombardment, noun from bombard, from Fr. bombarder, from bombarde "mortar, catapult" from bombe, from It. bomba, probably from L. bombus "a booming sound," from Gk. bombos "deep and hollow sound."

A → helium flash event that occurs during the → post-AGB phase. Some of the central stars of planetary nebulae (→ CSPN) experience a final → thermal pulse after having achieved a → white dwarf configuration and begun their descent along a → white dwarf cooling track of nearly constant radius. During such a pulse, most of the hydrogen remaining in the star at pulse onset is incorporated into the helium-burning convective shell and completely burned. Following the pulse, the star swells briefly to → red giant dimensions (Iben et al. 1983; ApJ 264, 605).

→ late; → helium; → flash.

In evolutionary models of → low-mass and → intermediate-mass stars, the occurrence of a → helium shell flash on the → horizontal branch of the → post-AGB track, while → hydrogen shell burning is still going on.

→ late; → thermal; → pulse.

In the → Hubble classification, a galaxy on the left part of the → Hubble sequence. See also → early-type galaxy.

→ late; → type; → galaxy.

A star of → spectral type K, M, S, or C, with a surface temperature lower than that of the Sun. → early-type star. See also → spectral classification.

→ late; → type; → star.

Present but not visible, apparent, or actualized; existing as potential (Dictionary.com). → latent heat.

From L. latentem (nominative latens), pr.p. of latere "to lie hidden."

Nahân "concealed, hid; clandestine;" Mid.Pers. nihân "secrecy, a secret place, a hiding place," nihânik "concealed;" Av. niδāti- "deposing, deposit."