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

A prefix, meaning "behind, after, later, subsequent to, posterior to."

From L. post (adverb and preposition) "behind, after, afterward," cognate with Gk. (Arcadian and Cyprian dialects) pos "toward, on, at;" Skt. paśca "behind, after, later."

Pasâ-, from pas "behind" (e.g.: pas-e pardé "behind the curtain"), variant pošt "back; the back; behind;" Mid.Pers. pas "behind, before, after;" O.Pers. pasā "after;" Av. pasca "behind (of space); then, afterward (of time);" cf. Skt. paścā "behind, after, later;" L. post, as above; O.C.S. po "behind, after;" Lith. pas "at, by;" PIE *pos-, *posko-.

A star in a short-lived evolutionary stage evolving from the → asymptotic giant branch toward higher → effective temperatures. The majority of low and intermediate mass stars (1 to 8 → solar masses) are believed to pass through this stage on their way to becoming → planetary nebulae.

→ post-; → asymptotic giant branch.

A star that has evolved off the → main sequence.

→ post-; → main sequence; → star.

→ post-Newtonian formalism.

→ post-; → Newtonian; → expansion.

An approximate version of → general relativity that applies when the → gravitational field is → weak, and the matter → velocity is → small. Post-Newtonian formalism successfully describes the gravitational field of the solar system. It can also be applied to situations involving compact bodies with strong internal gravity, provided that the mutual gravity between bodies is weak. It also provides a foundation to calculate the → gravitational waves emitted by → compact binary star systems, as well as their orbital evolution under radiative losses. The formalism proceeds from the Newtonian description and then, step by step, adds correction terms that take into account the effects of general relativity. The correction terms are ordered in a systematic way (from the largest effects to the smallest ones), and the progression of ever smaller corrections is called the → post-Newtonian expansion.

→ post-; → Newtonian; → formalism.

The stage following a nova outburst, when the star has returned to a quiescent state.

→ post-; → nova.

An evolved star whose → planetary nebula has dissipated.

→ post-; → planetary; → nebula; → star.