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

A specialist in → biophysics.

→ bio-; → physicist.

The science that deals with biological structures and processes involving the application of physical principles and methods.

Biophysics, from → bio- + → physics.

Zistfizik, from zist-, → bio- + fizik→ physics.

A substance or phenomenon whose presence in an object such as a → meteorite or an → exoplanet indicates the existence of life.

→ bio-; → signature.

The part of a planet or moon within which life can occur. It may include the crust, oceans, and atmosphere.

Biosphere, from → bio- + → sphere.

Zistsepehr, from zizt-, → bio-, + sepehr→ sphere.

The → magnetic field due to → electric current flowing in a long straight conductor is directly proportional to the current and inversely proportional to the distance of the point of observation from the conductor. The law is derivable from → Ampere's law, but was obtained experimentally by the authors.

Named after the French physicists Jean-Baptiste Biot (1774-1862) and Félix Savart (1791-1841); → law.

Ecology: The environment consisting of living organisms, which interact with each other and with their non-living surroundings.

Biotic adj. of → biotics; of → environment.

The science concerned with the functions of life, or vital activity and force.

From biotic, from Gk. biotikos "of or pertaining to life," from → bio- + -tic a suffix equivalent in meaning to → -ic.

Having two poles; having two opposite main structures or components.

Bipolar, from → bi- + → polar, from → pole.

Doqotbi, from do-, → bi-, + qotbi, → polar, from qotb, → pole.

Same as → bipolar outflow.

→ bipolar; → flow.

One of two beams of high-temperature, ionized gas ejected in two opposite directions associated with a → protostar. The collimated jets, a consequence of the → accretion process, can extend over distances of several → light-years.

→ bipolar; → jet.

An interstellar cloud of ionized gas with two main lobes which lie symmetrically on either side of a central star. The bipolar shape is generally due to the ejection of material by the central star in opposing directions.

→ bipolar; → nebula.

A flow of gaseous material in two opposite directions emanating from protostellar regions or from → evolved stars during the early post-→ AGB evolution. In protostellar regions → molecular outflows are pushed by → bipolar jets.

→ bipolar; → outflow.

Ostacân, → outflow; doqotbi→ bipolar.

A property of some crystalline materials (e.g. calcite, quartz) which have different indices of refraction associated with different crystallographic directions. Therefore, the crystal splits incident transmitted light into two beams, each polarized perpendicularly to the other. Also called double refraction.

Birefringence, from → bi- + refringence, from L. refringere "to break up," from → re- "back" + combination form of frangere "to break."

Došekast, from do- "two," → bi- + šekast "breaking," from šekastan "to break up," Mid.Pers. škastan, Av. skand- "to break."

Of or relating to → birefringence.

A type of narrow-band filter that uses the birefringence to produce selective absorption of polarized light.

→ birefringent; → filter.

Empty space undergoing → vacuum birefringence.

→ birefringent; → vacuum.

For a four dimensional → space-time, the → Schwarzschild metric is the only solution of → Einstein's field equations which describes the gravitational field created by a spherically symmetrical distribution of mass. The theorem implies that the gravitational field outside a sphere is necessarily static, and that the metric inside a spherical shell of matter is necessarily flat.

The theorem was first demonstrated in 1923 by George David Birkhoff (1884-1944), an American mathematician; → theorem

1) The act or process of bearing or bringing forth offspring.
2) The act or fact of being born.
3) The coming into existence of something.

M.E. byrthe; O.E. gebyrd; cf. O.H.G. giburt, Ger. geburt; PIE *bhrto, from *bher- "to bear."

1) Zâymân, from zây present stem of zâyidan, zâdan "to give birth" (Mid.Pers. zâtan; Av. zan- "to bear, give birth to a child, be born," infinitive zazāite, zāta- "born;" cf. Skt. janati "begets, bears;" Gk. gignesthai "to become, happen;" L. gignere "to beget," gnasci "to be born;" PIE base *gen- "to give birth, beget") + -mân a suffix forming verbal nouns, → organization.
2) Zâd, past stem of zâyidan, zâdan, as above; zâdmân with prefix -mân, as above.
3) Zâyeš, from zây, present stem of zâyidan + -eš suffix of verbal nouns, → -tion.

In star formation models, the population of binary components formed via random pairing of stars distributed according to the → canonical IMF.

→ birth; → binary; → population.

The path in the → H-R diagram that continuously → accreting stars follow. Stars on the birthline are difficult to observe, because they are hidden by the → accretion disk and a dense → cocoon of → interstellar matter. The star becomes visible once a sufficient amount of the surrounding matter has been dispersed. It follows that the young starsare observed generally between the birthline and the → zero-age main sequence (ZAMS). Before hydrogen ignition, gravitational contraction and deuterium burning are the main energy sources for the star. The localization of the birthline depends on the deuterium → accretion rate. First introduced by R. Behrend & A. Maeder, 2001 (A&A 373, 190).

→ birth; → line.