An Etymological Dictionary of Astronomy and Astrophysics

The episodic occurrence of abrupt → mass loss in → Be stars resulting in → Balmer lines in emission and → infrared excess. The Be phenomenon results from a combination of a long-term secular effect and short-term instabilities, such as pulsation. The secular evolution brings the star close enough to the critical → break-up velocity, so that the additional velocity field due to the instability may allow some mass ejection (Maeder 2011).

See also: → Be star; → phenomenon.

The episodic occurrence of abrupt → mass loss in → Be stars resulting in → Balmer lines in emission and → infrared excess. The Be phenomenon results from a combination of a long-term secular effect and short-term instabilities, such as pulsation. The secular evolution brings the star close enough to the critical → break-up velocity, so that the additional velocity field due to the instability may allow some mass ejection (Maeder 2011).

See also: → Be star; → phenomenon.

A hot star of → spectral type B showing → Balmer lines in emission. Be stars are fast rotators (spinning at about 200 km/sec) and have strong → stellar winds with important → mass loss.

See also: B, referring to the spectral type; e for emission lines;
→ star.

A hot star of → spectral type B showing → Balmer lines in emission. Be stars are fast rotators (spinning at about 200 km/sec) and have strong → stellar winds with important → mass loss.

See also: B, referring to the spectral type; e for emission lines;
→ star.

1. A collection of nearly parallel → light  → rays or a concentrated stream of → particles. See also → beam of light.
   

2. The area of the sky being observed at any one time by a → radio telescope.
   

3. The size of the → diffraction pattern; synonymous with point spread function.

Etymology (EN): M.E. beem, from O.E. beam “tree;” akin to O.H.G boum “tree,” Ger. Baum.

Etymology (PE): Tâbé, from tâb; tâbidan “light; to shine”

• -é noun suffix.

1. A collection of nearly parallel → light  → rays or a concentrated stream of → particles. See also → beam of light.
   

2. The area of the sky being observed at any one time by a → radio telescope.
   

3. The size of the → diffraction pattern; synonymous with point spread function.

Etymology (EN): M.E. beem, from O.E. beam “tree;” akin to O.H.G boum “tree,” Ger. Baum.

Etymology (PE): Tâbé, from tâb; tâbidan “light; to shine”

• -é noun suffix.

A parameter indicating the quality of an antenna as a direction measuring device. It is given by the ratio of the total
received power contained in the main beam of an antenna
to the total power (including the sidelobes); the same as main beam efficiency. See also → beamwidth.

See also: → beam; → efficiency.

A parameter indicating the quality of an antenna as a direction measuring device. It is given by the ratio of the total
received power contained in the main beam of an antenna
to the total power (including the sidelobes); the same as main beam efficiency. See also → beamwidth.

See also: → beam; → efficiency.

A relatively large bundle of → rays of light. See also → pencil of light.

See also: → beam; → light.

A relatively large bundle of → rays of light. See also → pencil of light.

See also: → beam; → light.

A narrow unidirectional flow of particles

See also: → beam; → particle.

A narrow unidirectional flow of particles

See also: → beam; → particle.

A partially reflecting mirror which permits a part of the light beam to pass through and reflects the rest.

Etymology (EN): → beam; splitter, from to split, from M.Du. splitten, from P.Gmc. spl(e)it-, PIE (s)plei- “to split, splice.”

Etymology (PE): Fâqgar, from fâq “split, breach, division” + tâbé→ beam.

A partially reflecting mirror which permits a part of the light beam to pass through and reflects the rest.

Etymology (EN): → beam; splitter, from to split, from M.Du. splitten, from P.Gmc. spl(e)it-, PIE (s)plei- “to split, splice.”

Etymology (PE): Fâqgar, from fâq “split, breach, division” + tâbé→ beam.

In single dish radio astronomy, any technique which forms the difference of signals received from two (or more) pointings on the sky without physically moving the main reflector of the antenna. By rapidly forming differences between sky positions that do and do not contain astronomical sources, beam switching can minimize the corruption of spectral baselines by non-idealities in the instrumental frequency response, or of continuum observations by atmospheric fluctuations.

See also: → beam; → switching.

In single dish radio astronomy, any technique which forms the difference of signals received from two (or more) pointings on the sky without physically moving the main reflector of the antenna. By rapidly forming differences between sky positions that do and do not contain astronomical sources, beam switching can minimize the corruption of spectral baselines by non-idealities in the instrumental frequency response, or of continuum observations by atmospheric fluctuations.

See also: → beam; → switching.

The angle between the two directions in the main beam at which the power response has fallen to half its maximum value. → beam efficiency.

Etymology (EN): From → beam + → width.

Etymology (PE): Tâbe-pahnâ, from tâbé, → beam, + pahnâ “width,” → broad.

The angle between the two directions in the main beam at which the power response has fallen to half its maximum value. → beam efficiency.

Etymology (EN): From → beam + → width.

Etymology (PE): Tâbe-pahnâ, from tâbé, → beam, + pahnâ “width,” → broad.

The periodic and alternatively strengthening and weakening of two waves of similar frequencies when they interfere with one another. In particular, the soft and loud sounds created by the
interference of two sound waves of similar frequencies.

Etymology (EN): M.E. beten, from O.E. beaten, from P.Gmc. *bautan; IER *bhau- “to strike.”

Etymology (PE): Zaneš, noun from zan- present tense stem of zadan “to beat, strike” + -š verbal noun suffix. Zadan from Mid.Pers. zatan, žatan; O.Pers./Av. jan-, gan- “to strike, hit, smite, kill” (jantar- “smiter”); cf.
Skt. han- “to strike, beat” (hantar- “smiter, killer”); Gk. theinein “to strike;” L. fendere “to strike, push;” Gmc. *gundjo “war, battle;” PIE *g^when- “to strike, kill.”

The periodic and alternatively strengthening and weakening of two waves of similar frequencies when they interfere with one another. In particular, the soft and loud sounds created by the
interference of two sound waves of similar frequencies.

Etymology (EN): M.E. beten, from O.E. beaten, from P.Gmc. *bautan; IER *bhau- “to strike.”

Etymology (PE): Zaneš, noun from zan- present tense stem of zadan “to beat, strike” + -š verbal noun suffix. Zadan from Mid.Pers. zatan, žatan; O.Pers./Av. jan-, gan- “to strike, hit, smite, kill” (jantar- “smiter”); cf.
Skt. han- “to strike, beat” (hantar- “smiter, killer”); Gk. theinein “to strike;” L. fendere “to strike, push;” Gmc. *gundjo “war, battle;” PIE *g^when- “to strike, kill.”

A Cepheid variable in which two or more almost identical periods of variability pass into and out of phase with each other, producing periodic amplitude fluctuations in their light curves. Beat periods are typically about 2 hours.

See also: → beat; → Cepheid.

A Cepheid variable in which two or more almost identical periods of variability pass into and out of phase with each other, producing periodic amplitude fluctuations in their light curves. Beat periods are typically about 2 hours.

See also: → beat; → Cepheid.

One of the frequencies that results from the combination of two waves of slightly different frquencies. A beat frequency is equal to the absolute value of the difference between the two frequencies. An unknown frequency can be determined by beating it with a reference frequency. More specifically, when the two frequencies are superimposed, the phase difference will change with time and wave interference alternate between constructive and destructive. The alterations of intensity brings about a beat frequency.

See also: → beat; → frequency.

One of the frequencies that results from the combination of two waves of slightly different frquencies. A beat frequency is equal to the absolute value of the difference between the two frequencies. An unknown frequency can be determined by beating it with a reference frequency. More specifically, when the two frequencies are superimposed, the phase difference will change with time and wave interference alternate between constructive and destructive. The alterations of intensity brings about a beat frequency.

See also: → beat; → frequency.

A system for estimating and reporting wind speeds which has 13 standardized categories and associated descriptions. The Beaufort scale ranges from 0 for complete calm to 12 for a cyclone. In this scale, the wind speed (in km/h) equals 3B^1.5, where B is the Beaufort number of the wind. The scale was originally devised for use at sea but has subsequently been modified for use over land.

See also: Named after Admiral Sir Francis Beaufort (1774-1857), who introduced the first version of the system in 1805; → scale.

A system for estimating and reporting wind speeds which has 13 standardized categories and associated descriptions. The Beaufort scale ranges from 0 for complete calm to 12 for a cyclone. In this scale, the wind speed (in km/h) equals 3B^1.5, where B is the Beaufort number of the wind. The scale was originally devised for use at sea but has subsequently been modified for use over land.

See also: Named after Admiral Sir Francis Beaufort (1774-1857), who introduced the first version of the system in 1805; → scale.

A combination of qualities that pleases the mind.

Etymology (EN): M.E. be(a)ute, from O.Fr. beautez, beltet “beauty, seductiveness, beautiful person” from V.L. bellitatem (nominative bellitas) “state of being handsome,” from L. bellus “pretty, charming.”

Etymology (PE): Zibâyi, from zibâ “beautiful,” related to zib “beauty, elegance, ornament,” zibidan “to suit, to adorn.”

A combination of qualities that pleases the mind.

Etymology (EN): M.E. be(a)ute, from O.Fr. beautez, beltet “beauty, seductiveness, beautiful person” from V.L. bellitatem (nominative bellitas) “state of being handsome,” from L. bellus “pretty, charming.”

Etymology (PE): Zibâyi, from zibâ “beautiful,” related to zib “beauty, elegance, ornament,” zibidan “to suit, to adorn.”

A large, amphibious rodent of the genus Castor, having sharp incisors, webbed hind feet, and a flattened tail, noted for its ability to dam streams with trees, branches, etc. (Dictionary.com).

Etymology (EN): M.E. bever, O.E. beofor, befor; cognate with Ger. Biber; Av. bawra-, bawri- “beaver” (Mid.Pers. bawrak “beaver”);
Skt. babhrav- “reddish-brown,” babhrus- “mangoose,” L. fiber “beaver” (Fr. bièvre “River of Beavers”); O.H.G. biorr; Lith. bêbrus; Rus. bobr “beaver.”

Etymology (PE): Bidastar “beaver,” of unknown origin.

A large, amphibious rodent of the genus Castor, having sharp incisors, webbed hind feet, and a flattened tail, noted for its ability to dam streams with trees, branches, etc. (Dictionary.com).

Etymology (EN): M.E. bever, O.E. beofor, befor; cognate with Ger. Biber; Av. bawra-, bawri- “beaver” (Mid.Pers. bawrak “beaver”);
Skt. babhrav- “reddish-brown,” babhrus- “mangoose,” L. fiber “beaver” (Fr. bièvre “River of Beavers”); O.H.G. biorr; Lith. bêbrus; Rus. bobr “beaver.”

Etymology (PE): Bidastar “beaver,” of unknown origin.

For the reason that; on account of.

Etymology (EN): M.E. bi cause “by cause,” from O.E. bi “by” (akin to Du. bij, O.H.G. bi, Ger. bei, Goth. bi) + → cause.

Etymology (PE): Zirâ, variants azirâ, zirâk, azirâk, from Mid.Pers. êt rây cê or ê(t) râd cê “because,” literally “this reason why;” from êd “this”
(O.Pers. aita; Av. aēta “this;” cf. Skt. etá); rây, → reason; cê “what” (O.Pers/Av. ci- “what, any,” collateral stem to ka- “who?, what?;” cf. Skt. ka-; Gk. po-; L. quo-; E. what, who; PIE *qwos/*qwes).

For the reason that; on account of.

Etymology (EN): M.E. bi cause “by cause,” from O.E. bi “by” (akin to Du. bij, O.H.G. bi, Ger. bei, Goth. bi) + → cause.

Etymology (PE): Zirâ, variants azirâ, zirâk, azirâk, from Mid.Pers. êt rây cê or ê(t) râd cê “because,” literally “this reason why;” from êd “this”
(O.Pers. aita; Av. aēta “this;” cf. Skt. etá); rây, → reason; cê “what” (O.Pers/Av. ci- “what, any,” collateral stem to ka- “who?, what?;” cf. Skt. ka-; Gk. po-; L. quo-; E. what, who; PIE *qwos/*qwes).

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.

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

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.

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

To come, change, or grow to be.

Etymology (EN): 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.

Etymology (PE): 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.”

To come, change, or grow to be.

Etymology (EN): 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.

Etymology (PE): 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.

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

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

See also: 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.

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

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.

See also: 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.

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

Etymology (PE): 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).

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

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

Etymology (PE): 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.

Etymology (EN): 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.”

Etymology (PE): 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).

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.

Etymology (EN): 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.”

Etymology (PE): 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.

→ Praesepe.

Manner of behaving or acting.

Etymology (EN): M.E. behavour, from behaven “to behave,” altered by model havour, from O.Fr. avoir “to have.”

Etymology (PE): 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.

Manner of behaving or acting.

Etymology (EN): M.E. behavour, from behaven “to behave,” altered by model havour, from O.Fr. avoir “to have.”

Etymology (PE): 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.

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

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.

See also: 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.

See also: 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.

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.

See also: 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.

Etymology (EN): Named after the heroine in Alexander Pope’s The Rape of the Lock.

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

Etymology (EN): 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.

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

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.

See also: 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.

Etymology (EN): From L. bellatrix “a female warrior,” fem. of bellator, from bellum “war.”

Etymology (PE): Merzam, Ar. name of the star; its other name is Nâjed.

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.

Etymology (EN): From L. bellatrix “a female warrior,” fem. of bellator, from bellum “war.”

Etymology (PE): 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.

Etymology (EN): 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.

Etymology (PE): 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.

1. (with preposition to) To be the property of.
   

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

Etymology (EN): 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.

Etymology (PE): 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.

See also: Third person present verb of → belong.

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

See also: 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.

Etymology (EN): O.E. belt, from P.Gmc. *baltjaz, from L. balteus “girdle;” → Orion.

Etymology (PE): Kamarband “belt,” from kamar “waist” (Mid.Pers. kamar “waist; belt, girdle,” Av. kamarâ- “belt”) + band “a band, tie, belt.”

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.

Etymology (EN): O.E. belt, from P.Gmc. *baltjaz, from L. balteus “girdle;” → Orion.

Etymology (PE): Kamarband “belt,” from kamar “waist” (Mid.Pers. kamar “waist; belt, girdle,” Av. kamarâ- “belt”) + band “a band, tie, belt.”

→ Orion’s Belt.

See also: → belt; → Orion.

→ Orion’s Belt.

See also: → 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.

See also: → belt, → Venus.

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.

See also: → 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.

See also: 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.

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.

See also: 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.

→ Coma Berenices.

The equation expressing → Bernoulli’s theorem: P + (1/2)ρV² + ρgz = constant, where P is the fluid → pressure, V is → velocity, ρ is → density,
g is the acceleration due to → gravity, and z is the vertical reference → level. The theree terms are called → static pressure, → dynamic pressure, and
→ hydrostatic pressure, respectively. The Bernoulli equation states that the total pressure along a → streamline is → constant.

See also: → Bernoulli’s theorem; → equation.

The equation expressing → Bernoulli’s theorem: P + (1/2)ρV² + ρgz = constant, where P is the fluid → pressure, V is → velocity, ρ is → density,
g is the acceleration due to → gravity, and z is the vertical reference → level. The theree terms are called → static pressure, → dynamic pressure, and
→ hydrostatic pressure, respectively. The Bernoulli equation states that the total pressure along a → streamline is → constant.

See also: → Bernoulli’s theorem; → equation.

A statement of the → conservation of energy in the → steady flow of an → incompressible, → inviscid fluid. Accordingly, the quantity (P/ρ) + gz + (V²/2) is → constant along any → streamline, where P is the fluid → pressure, V is the fluid → velocity, ρ is the mass → density of the fluid, g is the acceleration due to → gravity, and z is the vertical → height. This equation affirms that if the internal velocity of the flow goes up, the internal pressure must drop. Therefore, the flow becomes more constricted if the velocity field within it increases. Same as the → Bernoulli equation.

See also: After Daniel Bernoulli (1700-1782), the Swiss physicist and mathematician who put forward the theorem in his book Hydrodynamica in 1738; → theorem.

A statement of the → conservation of energy in the → steady flow of an → incompressible, → inviscid fluid. Accordingly, the quantity (P/ρ) + gz + (V²/2) is → constant along any → streamline, where P is the fluid → pressure, V is the fluid → velocity, ρ is the mass → density of the fluid, g is the acceleration due to → gravity, and z is the vertical → height. This equation affirms that if the internal velocity of the flow goes up, the internal pressure must drop. Therefore, the flow becomes more constricted if the velocity field within it increases. Same as the → Bernoulli equation.

See also: After Daniel Bernoulli (1700-1782), the Swiss physicist and mathematician who put forward the theorem in his book Hydrodynamica in 1738; → theorem.

1. A small, round fruit on particular plants and trees.
   

   2. Botany: Any of various small edible fruits such as the raspberry, blackberry, and strawberry.

Etymology (EN): M.E. berye, from O.E. berie “berry, grape,” cf. M.Du. bere, Ger. Beere, O.Sax. winberi, Gothic weinabasi “grape,” Norwegian and Danish bær, of unknown origin.

Etymology (PE): Pelâr, from Hamadâni, Malâyeri pellâr, pellâra “berry, grape berry;” cf. Laki, Xonsâri palâra “raisin grape,” Aligudarzi pellâr “part of a raison grape,” of unknown origin (related to berry, as above?).

1. A small, round fruit on particular plants and trees.
   

   2. Botany: Any of various small edible fruits such as the raspberry, blackberry, and strawberry.

Etymology (EN): M.E. berye, from O.E. berie “berry, grape,” cf. M.Du. bere, Ger. Beere, O.Sax. winberi, Gothic weinabasi “grape,” Norwegian and Danish bær, of unknown origin.

Etymology (PE): Pelâr, from Hamadâni, Malâyeri pellâr, pellâra “berry, grape berry;” cf. Laki, Xonsâri palâra “raisin grape,” Aligudarzi pellâr “part of a raison grape,” of unknown origin (related to berry, as above?).

A grey, very hard metallic chemical element; symbol Be. → Atomic number 4; → atomic weight 9.01218;
→ melting point about 1,278°C; → boiling point 2,970°C (estimated); → specific gravity 1.85 at 20°C; → valence +2. Beryllium occurs as beryl, from which it is obtained by electrolysis. Used for light alloys which are corrosion resistant. Beryllium was discovered by Louis Nicolas Vauquelin (1763-1829) in 1798. First isolated by Friedrich Wöhler (1800-1882) in 1828.

See also: From L. beryll(us), from beryl, a mineral, beryllium aluminum silicate, Be₃Al₂Si₆O₁₈, M.E. beril, from O.Fr., from L. berillus, from Gk. beryllos, + → -ium.

A grey, very hard metallic chemical element; symbol Be. → Atomic number 4; → atomic weight 9.01218;
→ melting point about 1,278°C; → boiling point 2,970°C (estimated); → specific gravity 1.85 at 20°C; → valence +2. Beryllium occurs as beryl, from which it is obtained by electrolysis. Used for light alloys which are corrosion resistant. Beryllium was discovered by Louis Nicolas Vauquelin (1763-1829) in 1798. First isolated by Friedrich Wöhler (1800-1882) in 1828.

See also: From L. beryll(us), from beryl, a mineral, beryllium aluminum silicate, Be₃Al₂Si₆O₁₈, M.E. beril, from O.Fr., from L. berillus, from Gk. beryllos, + → -ium.

From Friedrich Wilhelm Bessel (1784-1846), German astronomer and mathematicians, who made fundamental contributions to positional and spherical astronomy.

From Friedrich Wilhelm Bessel (1784-1846), German astronomer and mathematicians, who made fundamental contributions to positional and spherical astronomy.

A linear second-order differential equation, the solutions to which are called Bessel functions.

Etymology (EN): From → Bessel; → equation

Etymology (PE): Hamugeš, → equation.

A linear second-order differential equation, the solutions to which are called Bessel functions.

Etymology (EN): From → Bessel; → equation

Etymology (PE): Hamugeš, → equation.

Same as → 61 Cygni, the first star whose distance was measured, by Friedrich Bessel in 1838.

See also: → Bessel; → star.

Same as → 61 Cygni, the first star whose distance was measured, by Friedrich Bessel in 1838.

See also: → Bessel; → star.

Of or pertaining to Friedrich Wilhelm Bessel (1784-1846) or to his discoveries. → Besselian day number → → Bessel equation → Besselian star constant → → Besselian year.

See also: → Bessel.

Of or pertaining to Friedrich Wilhelm Bessel (1784-1846) or to his discoveries. → Besselian day number → → Bessel equation → Besselian star constant → → Besselian year.

See also: → Bessel.

Any of the five quantities denoted by A, B, C, D, and E used in conjunction with → Besselian star constants for the reduction of a star’s → mean catalog place to its → apparent place.

See also: → Besselian;
→ day; → number.

Any of the five quantities denoted by A, B, C, D, and E used in conjunction with → Besselian star constants for the reduction of a star’s → mean catalog place to its → apparent place.

See also: → Besselian;
→ day; → number.

Any of the eight quantities denoted by a, b, c, d (for → right ascension) and a’, b’, c’, d’ (for → declination) used in conjunction with → Besselian day numbers for the reduction of star’s → mean catalog place.

See also: → Besselian;
→ star; → constant.

Any of the eight quantities denoted by a, b, c, d (for → right ascension) and a’, b’, c’, d’ (for → declination) used in conjunction with → Besselian day numbers for the reduction of star’s → mean catalog place.

See also: → Besselian;
→ star; → constant.

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.

See also: → Besselian; → year.

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.

See also: → Besselian; → year.

In a scatter plot, a mathematical line or curve that passes as near to as many of the data points as possible.

Etymology (EN): Best, M.E., from O.E. betst, akin toi O.E. bot “remedy.” Fit, from M.E. fitten “to marchal troops,” from or akin to M.Dutch vitten “to be suitable.”

Etymology (PE): Behtarin supperlative of beh “good, fine” (Mid.Pers. veh “better, good,” O.Pers. vahav-, vahu-, Av. vah-, vohu- “good,” cf. Skt. vasu- “good,” Hittite wasu-, Gaulish vesus “good”) + saz, from sazidan “to be fit, proper,” from Mid.Pers. saz, sazistan “to be fitting, proper.”

In a scatter plot, a mathematical line or curve that passes as near to as many of the data points as possible.

Etymology (EN): Best, M.E., from O.E. betst, akin toi O.E. bot “remedy.” Fit, from M.E. fitten “to marchal troops,” from or akin to M.Dutch vitten “to be suitable.”

Etymology (PE): Behtarin supperlative of beh “good, fine” (Mid.Pers. veh “better, good,” O.Pers. vahav-, vahu-, Av. vah-, vohu- “good,” cf. Skt. vasu- “good,” Hittite wasu-, Gaulish vesus “good”) + saz, from sazidan “to be fit, proper,” from Mid.Pers. saz, sazistan “to be fitting, proper.”

The brightest star in the constellation → Andromeda with an average → apparent visual magnitude of 2.05. It is a red (B - V = +1.57), → giant star of → spectral type M0 III. Beta And lies at a distance of 197 ± 7 → light-years (61 ± 2 → parsecs). It has a mass of 3-4 Msun (→ solar mass), a → luminosity of ~ 2,000 Lsun (→ solar luminosity), and a radius of 100 Rsun (→ solar radius). Its other designations include:

Mirach, Merach, Mirac, Mizar, 43 Andromedae, BD+34°198, HD 6860, HIP 5447, HR 337, LTT 10420, and SAO 54471.

Beta And happens to lie nearly along the → line of sight to the galaxy → NGC 404. This galaxy, known as → Mirach’s Ghost, is visible seven arc-minutes away.

See also: Beta, a Greek letter of alphabet used in the → Bayer designation; → Andromeda

The brightest star in the constellation → Andromeda with an average → apparent visual magnitude of 2.05. It is a red (B - V = +1.57), → giant star of → spectral type M0 III. Beta And lies at a distance of 197 ± 7 → light-years (61 ± 2 → parsecs). It has a mass of 3-4 Msun (→ solar mass), a → luminosity of ~ 2,000 Lsun (→ solar luminosity), and a radius of 100 Rsun (→ solar radius). Its other designations include:

Mirach, Merach, Mirac, Mizar, 43 Andromedae, BD+34°198, HD 6860, HIP 5447, HR 337, LTT 10420, and SAO 54471.

Beta And happens to lie nearly along the → line of sight to the galaxy → NGC 404. This galaxy, known as → Mirach’s Ghost, is visible seven arc-minutes away.

See also: Beta, a Greek letter of alphabet used in the → Bayer designation; → Andromeda

The second brightest star in the constellation → Cepheus and the prototype of → Beta Cephei variables. It is a variable B2 type → giant star with a visual magnitude of 3.23 varying with a period of 4.57 hours. Its mass is a dozen times that of the Sun. Beta Cephei is a → triple system lying at a distance of about 600 → light-years. The inner → spectroscopic companion, → spectral type A, is only about 45 AU away, and takes around 90 years to orbit. The third visual companion is at least 2400 AU away, with an orbital period of at least 30,000 years.

See also: Beta (β), the second letter of the Gk. alphabet; → Cepheus.

The second brightest star in the constellation → Cepheus and the prototype of → Beta Cephei variables. It is a variable B2 type → giant star with a visual magnitude of 3.23 varying with a period of 4.57 hours. Its mass is a dozen times that of the Sun. Beta Cephei is a → triple system lying at a distance of about 600 → light-years. The inner → spectroscopic companion, → spectral type A, is only about 45 AU away, and takes around 90 years to orbit. The third visual companion is at least 2400 AU away, with an orbital period of at least 30,000 years.

See also: Beta (β), the second letter of the Gk. alphabet; → Cepheus.

A variable star, of early B or late O types, undergoing radial pulsations with short periods (< 1 day). Beta Cephei stars are confined within a narrow band of the → H-R diagram above the upper → main sequence. They are believed to be near the end of core hydrogen-burning stars of approximately 10 to 20 solar masses. The famous bright stars → Spica and → Mirzam belong to this family.

See also: → Beta Cephei; → variable.

A variable star, of early B or late O types, undergoing radial pulsations with short periods (< 1 day). Beta Cephei stars are confined within a narrow band of the → H-R diagram above the upper → main sequence. They are believed to be near the end of core hydrogen-burning stars of approximately 10 to 20 solar masses. The famous bright stars → Spica and → Mirzam belong to this family.

See also: → Beta Cephei; → variable.

The transformation of a → radioactive nuclide in which a → beta particle is emitted. In beta minus decay, a → neutron changes into a → proton, → antineutrino, and → electron: n → p + e + ν^-. Beta plus decay involves the conversion of a proton to a neutron, → positron, and → neutrino: p → n + e⁺ + ν.

See also: Beta (β), from → beta particle; → decay.

The transformation of a → radioactive nuclide in which a → beta particle is emitted. In beta minus decay, a → neutron changes into a → proton, → antineutrino, and → electron: n → p + e + ν^-. Beta plus decay involves the conversion of a proton to a neutron, → positron, and → neutrino: p → n + e⁺ + ν.

See also: Beta (β), from → beta particle; → decay.

→ beta particle.

See also: → beta particle; → minus; → decay.

→ beta particle.

See also: → beta particle; → minus; → decay.

An → electron or a → positron emitted from an unstable nucleus during a → radioactive process known as → beta decay.

See also: The term “beta particle” relates to the early history of the → radioactivity studies when the nature of the emergent particles was not elucidated; → particle.

An → electron or a → positron emitted from an unstable nucleus during a → radioactive process known as → beta decay.

See also: The term “beta particle” relates to the early history of the → radioactivity studies when the nature of the emergent particles was not elucidated; → particle.

The second brightest star, with an apparent magnitude of 3.86, in the southern constellation → Pictor. Beta Pic is a young star of spectral type A lying 63 → light-years away. It has a luminosity 8.6 times that of the Sun and its surface temperature is 8250 K. Beta Pic is surrounded by a dust and gas disk stretching 400 A.U. away from the star in each direction, 10 times the average distance of Pluto from the Sun. The disk is not symmetric, one side is brighter than the other. Moreover, it has an inner clear zone about the size of our solar system (some 30 A.U.). Recently a probable giant → exoplanet lying in the disk has been imaged.

See also: Beta (β), the second letter of the Gk. alphabet; → Pictor.

The second brightest star, with an apparent magnitude of 3.86, in the southern constellation → Pictor. Beta Pic is a young star of spectral type A lying 63 → light-years away. It has a luminosity 8.6 times that of the Sun and its surface temperature is 8250 K. Beta Pic is surrounded by a dust and gas disk stretching 400 A.U. away from the star in each direction, 10 times the average distance of Pluto from the Sun. The disk is not symmetric, one side is brighter than the other. Moreover, it has an inner clear zone about the size of our solar system (some 30 A.U.). Recently a probable giant → exoplanet lying in the disk has been imaged.

See also: Beta (β), the second letter of the Gk. alphabet; → Pictor.

→ beta particle.

See also: → beta particle; → plus; → decay.

→ beta particle.

See also: → beta particle; → plus; → decay.

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.

See also: → meteoroid.

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.

See also: → meteoroid.

The → red supergiant that is the second brightest star in the constellation → Orion. Betelgeuse is one of the biggest stars known with a size of almost 1,000 times larger than the Sun, corresponding to an angular diameter of 43.76 ± 0.12 milli-arcseconds (Perrin et al. 2004, A&A 418, 675). It is a → semiregular variable whose → apparent visual magnitude varies between 0.2 and 1.2 shining very rarely more brightly than its neighbor → Rigel. The energy released by Betelgeuse is estimated to be only 13% in the form of visible light, with most of its radiation being at → infrared wavelengths. The distance of Betelgeuse is 643±146 → light-years (Harper et al. 2008, AJ 135, 1430), while its luminosity
is about 140,000 times that of the Sun (→ solar luminosity). Its → spectral type is M2 Iab, its → surface temperature about 3,600 K, and its → initial mass 10 to 20 → solar masses (M_sun).
Neilson & Lester (2011, arXiv:1109.4562) recently proposed a mass of 11.6 (+5.0, -3.9) M_sun
for Betelgeuse, while Dolan et al. (2008, BAPS 53, APR.S8.6) obtained about 21 M_sun. Its → rotation period is estimated to be about 17 years (Uittenbroek et al. 1998, AJ 116, 2501). Recent observations with the → Very Large Telescope resolve not only the apparent surface of Betelgeuse, but also reveal a large and previously unknown plume of gas extending into space from the surface of the star (Kervella et al. 2009, A&A 504, 115).
The plume extends to at least six times the diameter of the star, corresponding to the distance between the Sun and Neptune. This detection suggests that the whole outer shell of Betelgeuse is not shedding matter evenly in all directions. More recently, an image of the surface of the star was obtained using long → baseline → interferometry at infrared wavelengths (Haubois et al. 2009, A&A 508, 923). It shows the presence of an irregular flux distribution possibly caused by enormous → convective cells. A very large dusty envelope has also been observed at larger distances from the star (Kervella et al. 2011, A&A 531, A117).

Etymology (EN): Betelgeuse, from Ar. Ibt al-Jauza’ (ابط‌الجوزاء)
“the armpit of Jauza’,” from ibt “armpit” + Jauza’ “Orion.”

Etymology (PE): Ebtoljowzâ, from Ar. Ibt al-Jauza’.

The → red supergiant that is the second brightest star in the constellation → Orion. Betelgeuse is one of the biggest stars known with a size of almost 1,000 times larger than the Sun, corresponding to an angular diameter of 43.76 ± 0.12 milli-arcseconds (Perrin et al. 2004, A&A 418, 675). It is a → semiregular variable whose → apparent visual magnitude varies between 0.2 and 1.2 shining very rarely more brightly than its neighbor → Rigel. The energy released by Betelgeuse is estimated to be only 13% in the form of visible light, with most of its radiation being at → infrared wavelengths. The distance of Betelgeuse is 643±146 → light-years (Harper et al. 2008, AJ 135, 1430), while its luminosity
is about 140,000 times that of the Sun (→ solar luminosity). Its → spectral type is M2 Iab, its → surface temperature about 3,600 K, and its → initial mass 10 to 20 → solar masses (M_sun).
Neilson & Lester (2011, arXiv:1109.4562) recently proposed a mass of 11.6 (+5.0, -3.9) M_sun
for Betelgeuse, while Dolan et al. (2008, BAPS 53, APR.S8.6) obtained about 21 M_sun. Its → rotation period is estimated to be about 17 years (Uittenbroek et al. 1998, AJ 116, 2501). Recent observations with the → Very Large Telescope resolve not only the apparent surface of Betelgeuse, but also reveal a large and previously unknown plume of gas extending into space from the surface of the star (Kervella et al. 2009, A&A 504, 115).
The plume extends to at least six times the diameter of the star, corresponding to the distance between the Sun and Neptune. This detection suggests that the whole outer shell of Betelgeuse is not shedding matter evenly in all directions. More recently, an image of the surface of the star was obtained using long → baseline → interferometry at infrared wavelengths (Haubois et al. 2009, A&A 508, 923). It shows the presence of an irregular flux distribution possibly caused by enormous → convective cells. A very large dusty envelope has also been observed at larger distances from the star (Kervella et al. 2011, A&A 531, A117).

Etymology (EN): Betelgeuse, from Ar. Ibt al-Jauza’ (ابط‌الجوزاء)
“the armpit of Jauza’,” from ibt “armpit” + Jauza’ “Orion.”

Etymology (PE): Ebtoljowzâ, from Ar. Ibt al-Jauza’.

A unit of energy equal to 10⁴⁴ → joules or 10⁵¹ → ergs, corresponding to the amount of energy liberated in a typical → supernova explosion. It is used by some theoreticians.

See also: In honor of Hans Bethe (1906-2005), Nobel Prize in Physics (1967), for his work on the theory of stellar nucleosynthesis.
The unit name was proposed by Steven Weinberg (1933-) in 2006 for Bethe’s contributions to the supernova research aftre 1980.

A unit of energy equal to 10⁴⁴ → joules or 10⁵¹ → ergs, corresponding to the amount of energy liberated in a typical → supernova explosion. It is used by some theoreticians.

See also: In honor of Hans Bethe (1906-2005), Nobel Prize in Physics (1967), for his work on the theory of stellar nucleosynthesis.
The unit name was proposed by Steven Weinberg (1933-) in 2006 for Bethe’s contributions to the supernova research aftre 1980.

An → ansatz initially used to deal with → antiferromagnetism
in a quantum system. It has been generalized to various quantum → n-body problems.

See also: First introduced by Hans Bethe (1906-2005), → bethe; → ansatz.

An → ansatz initially used to deal with → antiferromagnetism
in a quantum system. It has been generalized to various quantum → n-body problems.

See also: First introduced by Hans Bethe (1906-2005), → bethe; → ansatz.