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

Belonging or pertaining exclusively or distinctly to a person, thing, or group. → proper mass; → proper motion; → proper time.

M.E., from O.Fr. propre, from L. proprius "one's own."

Saré "pure; principal."

A distance between two nearby events in the frame in which they occur at the same time. It is the distance measured by a ruler at the time of observation. Hence, for a cosmological time t, D_proper = D_C . a(t), where D_C is the → comoving distance, and a(t) is the → scale factor. In the present epoch a = a(t_obs) = 1, and D_proper = D_C.

→ proper; → distance.

Same as → rest mass.

→ proper; → mass.

The apparent motion of a star across the sky (not including a star's parallax), arising from the star's velocity through space with respect to the Sun. Proper motion is usually tabulated in star catalogs as changes in right ascension and declination per year or century. See also: → proper motion distance.

→ proper; → motion.

The distance derived from the → proper motion of an object. If an object has a known → transverse velocity  u, and has an observed angular motion of dθ/dt, then the proper motion distance is defined as: d = u/(dθ/dt).

→ proper; → motion; → distance

Of two sets A and B, the set A if it is contained in B (A ⊂ B) but is not equal to B (A ≠ B).

→ proper; → subset.

In general relativity, the time as measured on a clock that travels with the observer in the same system. An accelerated clock will measure shorter time intervals between events than a non-accelerated clock between the same events. → twin paradox.

→ proper; → time.

1) General: An essential or distinctive attribute or quality of a thing.
2) Physics: A quantity, such as length, mass, pressure, temperature, or volume, that relates to the state of a system and can be expressed in numbers obtained from well-defined measurement operations.

From M.E. propriete "ownership, something owned, one's own nature," from M.Fr. propriété, from L. proprietas "ownership, property, propriety," literally "special character," noun of quality from proprius "one's own, special."

Dârâk "thing owned," from dâr present stem of dâštan "to have, to possess" + -âk (on the model of xorâk, pušâk, kâvâk). The first element dâštan, from Mid.Pers. dâštan, O.Pers./Av. root dar- "to hold, keep back, maintain, keep in mind;" Skt. dhr- "to to hold, keep, preserve," dharma- "law;" Gk. thronos "elevated seat, throne;" L. firmus "firm, stable;" Lith. daryti "to make;" PIE *d^her- "to hold, support."