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

A supernova arising from the → core collapse of a → massive star. Same as → Type Ib, → Type Ic, or → Type II supernova.

→ core; → collapse; → supernova.

A → radio-loud quasar in which the central source is enhanced by → relativistic beaming and characterized by a → flat  → spectrum. It has been conjectured that this phenomenon is an → orientation effect. If a radio-loud quasar is seen along its → jet, it will appear as a core-dominated source. See also → lobe-dominated quasar.

→ core; → dominate; → quasar.

A radio galaxy characterized by an emission "halo" surrounding a more intense "core". About 20% of the known extended radio sources are of the core-halo type.

→ core; → halo; → galaxy.

A prefix meaning "before, prior to, in advance of, early, beforehand, in front of."

M.E., from O.Fr. pré-, from L. præ (adverb) "before."

Piš- "before; in front," from Mid.Pers. pêš "before, earlier," O.Pers. paišiya "before; in the presence of."

A precursor of a small, loosely bound → star cluster (→ bound cluster) as well as an → OB association, with masses ranging from about 10 to 1000 → solar masses or more.

→ pre-; → cluster; → core.

Same as → PG 1159 star.

→ post-; → degenerate; → star.

A technique in spectroscopy which uses a combination of several dispersive elements (prisms in series or a grism) before focusing the light on the primary disperser, usually a grating, in order to achieve high spectral resolutions.

→ pre-; → dispersion.

A → binary system whose components are → pre-main sequence stars.

→ pre-; → main sequence; → binary.

A → Herbig AeBe star displaying → forbidden emission lines in its spectrum.

→ pre-; → main; → sequence; → B[e] star.

A star that evolves in the → Hayashi phase and has not yet reached the → zero-age main sequence.

→ pre-; → main sequence, → star.

The stage of a star before its eruption to become a nova.

→ pre-; → nova; → stage.

An adjective relating to a stage before the formation of a → protostar. → pre-stellar core.

→ pre-; → stellar.

A small, gravitationally unstable molecular → clump of typical size of less than 0.1 pc resulting from → gravitational collapse and → fragmentation of a larger → molecular cloud. It is a centrally concentrated structure which evolves into a → class 0 object, where eventually a single star or a stellar system is formed. Core masses range between 0.5 and 5 solar masses, with a mean number density of at least 10⁴-10⁵ cm^-3, and a temperature as low as about 10 K. A pre-stellar core evolves into a → Class 0 object. Also called dense core.

→ pre-stellar; → core.

A → post-planetary nebula star that is approaching the top of the → white dwarf sequence. These stars have exhausted the capacity of → nuclear burning in their cores.

→ pre-; → white; → dwarf.

A prefix meaning "again, anew" to indicate repetition (as rebuild, retell), "back, backward" to indicate "withdrawal" or "backward motion" (react, recall), or sometimes merely intensive (refine, resolve).

M.E., from O.Fr., from and L. re- "again, back."

Vâ-, variant bâz-, prefix denoting "reversal, opposition; separation; repetition; open; off; away," 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."

A combining form meaning "having and dealing with three dimensions of space; solid."

From stereo a shortening of stereotype, from Fr. stéréotype (adj.) "printing by means of a solid plate of type," from Gk. stereos "solid."

Loan from Fr., as above.