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

Prefix meaning "not."

From Gk. a-, an- "not," compare with O.Pers./Av. a-, an- "not, without," Skt. a-, an- "not," L. in-, a variant of PIE *ne- "not".

A-, an-, from O.Pers./Av. negation prefix appearing before consonants and vowels respectively. A couple of examples in Mod.Pers.: amordâd "immortality, name of the fifth month in the Iranian calendar," anušé; "fortunate, happy," anirani "non Iranian," âhu "vice, defect," âsoqdé "unburnt, half-burnt wood."
Bi- privative prefix, from Mid.Pers. abi-, O.Pers. *apaiy-, Av. apa-.
Nâ- negation prefix "not, no," Mid.Pers. ne, O.Pers. naiy, Av. na-, (particle of negation noit), Skt. na-, (ned), Gk. né- "not," L. ne-, in-, un-, PIE *ne-.

Same as → A star.

A, letter of alphabet used in the → Harvard classification; → type; → star.

Prefix meaning: 1) up, upward (anode); 2) back, backward (ananym); 3) again, anew (anagenesis); 4) exceedingly (anamorphism).

From Gk. ana- "up, on, upon, throughout, again," cognate with Av. ana "on, over, along," O.Pers. anâ "throughout," O.E. on; PIE base *ano- "on, upon, above".

Ânâ-, from ana, anâ, Av. and O.Pers. counterparts of Gk. ana-, as above.

The total number of → protons and → neutrons in the → nucleus of an → atom (symbol A). For example, Oxygen-16 has a mass number of sixteen, because it has eight protons and eight neutrons.

→ atomic; → mass; → number.

A solid object with a mass about 10^-18-10^-15 kg in → interplanetary space that moves in hyperbolic orbit as a result of the solar → radiation pressure.

→ meteoroid.

A 3.6 m optical/infrared telescope jointly owned and operated by the Canadian National Research Council (NRC), the French Centre National de la Recherche Scientifique (CNRS), and the University of Hawaii. It became operational in 1979. The observatory is located atop the summit of Mauna Kea, a 4200 m, dormant volcano located on the island of Hawaii. The Observatory headquarters is located in Waimea (also known as Kamuela by the US Postal Service). Situated at the low latitude of Hawaii (+19° 45'), there is a fairly large sky overlapping with that of the → European Southern Observatory (ESO)  → La Silla observatory (δ = -29° 15'). The point where an object is seen at the same → zenith distance from La Silla and from Mauna Kea, when it crosses the meridian, is δ =-5°. Taking into consideration also the difference in elevation between the observatories, the → declination at which one has equal air mass is moved down to δ =-18°. The extreme limit of observing from Mauna Kea is -60° (10° above horizon) but all programs below -20° are most efficiently carried out from ESO.

Canada, from the St. Lawrence Iroquoian word kanata, meaning "village" or "settlement;" France, from the L. Francia "country of the Franks;" Hawaii, named for Hawai'iloa, a legendary figure from Hawaiian mytholgy; → telescope.

A prefix meaning "down," also "against; back; by, about; with, along," occurring originally  in loanwords from Greek; variants cat- and cath-, as in catalog, cataclysm, cataract, cathode, catastrophe, etc.

From Gk. kata-, before vowels kat-, from kata "down from, down to."

Katâ-, kâtâ-, kât-, kat-, loan from Gk., as above.

A prefix meaning "against; contrary; opposing."

From L. contra "against," passed (via O.Fr.) into E. as → counter-.

Prefix meaning "ten" and "ten times" used in terms belonging to the metric system.

From Fr. déca-, from L. deca-, dec-, from Gk. deka "ten;" cf. Av. dasa "ten," Mod.Pers. dah "ten," Skt. dasa, PIE *dekm (Dan. ti, Du. tien, Ger. zehn, E. ten, Fr. dix).

Dekâ-, from Fr. as above.

A prefix in the SI system of units denoting 10¹⁸.

Adopted in 1991, from Gk. ex "six," because it is equal to (1000)⁶.

Prefix meaning "outside; beyond the scope of; in addition to what is used or expected." Also extro-.

M.E., from L. extra, adverb and preposition, "outside, except, beyond," from exter "outward, on the outside."

Ostar-, from os-, → ex-, + -tar comparative suffix (Mid.Pers. -tar; Av. -tara; PIE base *-tero); borun-, from borun "out, the outside" (Mid.Pers. bêron, from bê "outside, out, away" + rôn "side, direction;" Av. ravan- "(course of a) river").

A space observatory, formerly named GLAST, devoted to the study of → gamma rays emitted from astrophysical objects. Developed by NASA in collaboration with the U.S. Department of Energy, along with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the United States, Fermi was launched on June 11, 2008. The main instrument, the Large Area Telescope (LAT), is an imaging → camera covering the energy range from about 20 → MeV to more than 300 → GeV. Such gamma rays are emitted only in the most extreme conditions, by particles moving very nearly at the → speed of light. The LAT's → field of view covers about 20% of the sky at any time, and it scans continuously, covering the whole sky every three hours. Another instrument, the Gamma-ray Burst Monitor (GBM) has a field of view several times larger than the LAT and provides → spectral coverage of → gamma-ray burst that extends from the lower limit of the LAT down to 10 → keV.

→ Fermi; → gamma ray; → space; → telescope.

A computer experiment that was aimed to study the → thermalization process of a → solid. In other words, the goal was to see whether there is an approximate → equipartition of energy in the system, which would mean that the motion is → chaotic. Using computer simulation, Fermi-Pasta-Ulam studied the behavior of a chain of 64 mass particles connected by → nonlinear springs. In fact, they were looking for a theoretical physics problem suitable for an investigation with one of the very first computers, the he MANIAC (Mathematical Analyzer, Numerical Integrator and Computer). They decided to study how a → crystal evolves toward → thermal equilibrium by simulating a chain of particles, linked by a quadratic interaction potential, but also by a weak nonlinear interaction. Fermi-Pasta-Ulam assumed that if the interaction in the chain were nonlinear, then an exchange of energy among the normal modes would occur, and this would bring forth the equipartition of energy, i.e. the thermalization. Contrary to expectations, the energy revealed no tendency toward equipartition. The system had a simple quasi-periodic behavior, and no → chaoticity was observed. This result, known as the Fermi-Pasta-Ulam paradox, shows that → nonlinearity is not enough to guarantee the equipartition of energy (see, e.g., Dauxois et al., 2005, Eur. J. Phys., 26, S3).

E. Fermi, J. Pasta, S. Ulam, 1955, Los Alamos report LA-1940; → problem.

The study of → gamma rays from → extraterrestrial → sources, especially → gamma-ray bursts.

→ gamma ray; → astronomy.

An intense discharge of → gamma rays, which range in duration from tenth of a second to tens of seconds and occur from sources widely distributed over the sky. The radio wave → afterglow from the → burst can last more than a year, making long-term observations of the sources possible. The favored hypothesis is that they are produced by a relativistic jet created by the merger of two → compact objects (specifically two → neutron stars or a neutron star and a → black hole). Mergers of this kind are also expected to create significant quantities of neutron-rich radioactive species, whose decay should result in a faint → transient, known as a → kilonova, in the days following the burst. Indeed, it is speculated that this mechanism may be the predominant source of stable → r-process elements in the Universe. Recent calculations suggest that much of the kilonova energy should appear in the → near-infrared spectral range, because of the high optical opacity created by these heavy r-process elements (Tanvir et al., 2017, Nature 500, 547).

→ gamma rays; → burst.

The → object or → phenomenon at the origin of a → gamma-ray burst.

→ gamma ray; → burster.

1) An astronomical object that emits → gamma rays.
2) A radioactive material that emits gamma rays in a form that can be used in medical imaging.

→ gamma ray; → source.

A follow-up community network concerned with → gamma-ray burst (GRB)s. It deals with: 1) locations of GRBs and other → transients detected by spacecraft (most in real-time while the GRB is still bursting), and 2) reports of follow-up observations (the Circulars) made by ground-based and space-based optical, radio, X-ray, TeV, and other observers. The GCN Circulars allow the GRB follow-up community to make optimum use of its limited resources (labor and telescope time) by communicating what has already been done or will soon be done.

→ gamma ray; → coordinate; → network.

A prefix that is used to represent 10⁹ in the SI system.

From Gk. gigas, → giant.

A combining form meaning "seven."

From Gk. hepta "seven;" cognate with L. septem; Pers. haft, as below; Du. zeven, O.H.G. sibun, Ger. sieben, E. seven.

Haft-, from haft "seven;" Mid.Pers. haft; Av. hapta; cf. Skt. sapta; Gk. hepta, L. septem; PIE *septm.