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

A compact infrared source in the Orion molecular cloud (OMC-1). It is thought to be a very dusty compact H II region surrounding a young B0 or B1 star.

After Eric Becklin (1940-), and Gerry Neugebauer (1932-) who discovered the object in 1967; → object.

To come, change, or grow to be.

M.E. becumen; O.E. becuman "happen, come about," also "meet with, arrive;" akin to Du. bekomen, O.H.G. biqueman "obtain," Ger. bekommen, Goth. biquiman; from be- a prefix denoting several meanings, and → come.

Šodan "to become, to go, to pass, to change," from Mid.Pers. šudan, šaw- "to go;" Av. š(ii)auu-, šiyav- "to move, go," šiyavati "goes," šyaoθna- "activity; action; doing, working;" O.Pers. šiyav- "to go forth, set," ašiyavam "I set forth;" cf. Skt. cyu- "to move to and fro, shake about; to stir," cyávate "stirs himself, goes;" Gk. kinein "to move;" Goth. haitan "call, be called;" O.E. hatan "command, call;" PIE base *kei- "to move to and fro."

The → SI unit of → radioactivity. One becquerel corresponds to the → disintegration of one atom per second. Abbreviation: Bq. → curie.

Named for the French physicist Henri Becquerel (1852-1908), who discovered radioactivity in 1896.

A → dwarf spheroidal galaxy belonging to the → Local Group that was discovered serendipitously in 2019. Bedin I was detected using extremely deep → HST images (V ~ 30 mag) obtained for the purpose of investigating the → white dwarf cooling track of the Galactic → globular cluster NGC 6752. Bedin I is too faint and too close to the core of NGC 6752 for detection in earlier surveys. The discovery paper derives a → distance modulus of (m - M)₀ = 29.70 ± 0.13 mag from the observed → red giant branch, i.e. ~ 8.7 → megaparsecs (~ 30 million → light-years), and a size of ~ 840 × 340 pc, about one-fifth the size of the → Large Magellanic Cloud. This object is most likely a relatively isolated → satellite galaxy of the nearby great → spiral galaxy NGC 6744. The study suggests the presence of an old (~ 13 Gyr) and → metal-poor ([Fe/H] ~ -1.3) population in Bedin I.

Named after the first author of the discovery paper, L. R. Bedin et al., 2019, MNRAS 484, L54.

Solid → rock present beneath any → soil, → sediment, or other surface cover. In some locations it may be exposed at earth's surface.

Bedrock, from bed (O.E. bed, from P.Gmc. *badjam "sleeping place dug in the ground;" PIE *bhedh- "to dig, pierce") + → rock.

Sangbastar, from sang "stone, rock," → stone, + bastar "bed" (Mid.Pers. vistarak, cognate with Mod.Pers. gostar "a bed; spreading; scatterer," Av. star-, starəta- "spread," from star- "to spread," Skt. strnâti).

Any tree of the genus Fagus, especially Fagus sylvatica of Europe, having smooth grayish bark. In Iran Fagus orientalis populates Caspian highland forests from Âstârâ to Gorgân.

M.E. beche, from O.E. becew; cf. Dutch beuk, Ger. Buche, from PIE root *bhagos "beech tree;" also cf. Gk. phegos "oak," L. fagus "beech," Rus. buzina "elder."

Râš, as named in Gilân, Râmsar, Šahsavâr, Kalârdašt. Its other names: (Mâzandarân) mers, (Ammaârlu, Manjil) râj, (Tevâleš, Mt. Dorfak) aluš, alâš, âlâš, (Nur) celer, celar (Iranica).

→ Praesepe.

Manner of behaving or acting.

M.E. behavour, from behaven "to behave," altered by model havour, from O.Fr. avoir "to have."

Raftâr "behavior, walking, going," from raft past tense stem of raftan "to go, walk, proceed" (present tense stem row-, Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- "to go; to attack") + -âr prefix forming action noun.

The mathematical expression giving the → entropy, S, of a → black hole as a function of the area of its → event horizon, A: S = (kc³A)/(4Għ), where k is → Boltzmann's constant, ħ is the → reduced Planck's constant, and G the → gravitational constant. It can also be expressed by S = (kA)/(4l_P²), where l_P is the → Planck length. The existence of this entropy led to the prediction of the → Hawking radiation, because an entropy is associated with a temperature and a temperature to a → thermal radiation. The entropy of a black hole increases continuously because the fall of material into it increases its area.

For Jacob D. Bekenstein (1947-), an Israeli theoretical physicist, who contributed to the foundation of black hole thermodynamics; → formula.

A dimensionless unit to measure sound. One bel designates a ratio 10:1 between two quantities, P₁ and P₀, which have the dimension of a power: n [B] = log (P₁/P₀), in Bel units, with → natural logarithm. If one sound is 2 bels louder than another, this means the louder sound is 100 times more intense than the fainter one. It is also common to use this definition for quantities that are proportional to a power, such as energy, work, intensity, or voltage. The bel was too large for everyday use, so the → decibel (dB), equal to 0.1 bel, is more commonly used.

This unit was put forward by engineers of the Bell telephone network in 1923 and named in honor of the inventor of the telephone, Alexander Graham Bell (1847-1922), who also invented techniques for teaching speech to the deaf.

One of the small satellites of → Uranus discovered from the Voyager 2 photographs taken during its encounter with the planet in 1986.

Named after the heroine in Alexander Pope's The Rape of the Lock.

Any of a large number of inequality relations developed to study the → hidden variable hypothesis suggested in the → EPR paradox. Using Bell's inequalities, the → Aspect experiment showed that no local hidden variable theory can make predictions in agreement with those of quantum mechanics. If, in a measurement, the inequality is violated, the measurement is in agreement with the predictions of the quantum theory. If the equality is satisfied, it suggests that a classical, causal, and local model is adequate to explain the outcome of the measurements. See also → quantum entanglement.

John Stewart Bell (1928-1990); → inequality.

A bright, blue → giant star ( → spectral type B2 III), one of the main stars of the constellation → Orion. With a visual magnitude of 1.64, it is about 1000 times more luminous than the Sun, and lies at a distance of 243 → light-years.

From L. bellatrix "a female warrior," fem. of bellator, from bellum "war."

Merzam, Ar. name of the star; its other name is Nâjed.

1) (with preposition to) To be the property of.
2) (with preposition to) To be a part or adjunct of.

M.E. belongen, from be- intensive prefix, + longen "to go," from O.E. langian "pertain to, to go along with;" akin to Du. belangen, Ger. belangen; of unknown origin.

Pargetidan, literally "to surround, to relate with" (on the model of L. pertinere "pertain," Skt. parigraha- "surrounding; relation to"), from parget "to hold, seize, take around," from par- "around," → peri-, + get "to take, sieze," as in Tâleši gate "to take," Târi gata, Sorxeyi, Lâsgardi, Semnâni, Šâhmerzâdi -git- "take, seize," variants of gereftan "take, hold," → concept.

If x is an → element of a → set S, then x belongs to S and this is written x ∈ S.

Third person present verb of → belong.

A strip of leather or cloth worn around the waist. Something that resembles this type of band, e.g. → Gould's Belt, → Belt of Venus.

O.E. belt, from P.Gmc. *baltjaz, from L. balteus "girdle;" → Orion.

Kamarband "belt," from kamar "waist" (Mid.Pers. kamar "waist; belt, girdle," Av. kamarâ- "belt") + band "a band, tie, belt."

→ Orion's Belt.

→ belt; → Orion.

A pink to brownish border above the horizon separating the Earth's dark shadow on the sky from the sky above it. The Belt of Venus appears during a cloudless twilight just before sunrise or after sunset. It is due to scattered red sunlight in the atmosphere. Also called anti-twilight arc.

→ belt, → Venus.

A → European Space Agency (ESA) mission aimed at studying → Mercury, the least explored planet in the inner → Solar System. It was launched on 20 October 2018. Among several goals, BepiColombo will make a complete map of Mercury at different wavelengths. It will chart the planet's → mineralogy and elemental → composition, determine whether the interior of the planet is molten or not, and investigate the extent and origin of Mercury's → magnetic field, the properties of its → magnetosphere, and history of the planet. The trajectory will also be modified by eight planetary flybys: of Earth in April 2020, Venus in 2020 and 2021, and then six times of Mercury itself between 2021 and 2025. BepiColombo will enter Mercury orbit in December 2025. BepiColombo is a joint mission between ESA and the Japanese Aerospace Exploration Agency (JAXA), executed under ESA leadership.

Named after Giuseppe (Bepi) Colombo (1920-1984), a scientist who studied Mercury's orbital motion in detail as well as orbits and interplanetary travel in general.

→ Coma Berenices.