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

Apart or detached from others; separate; distinct. Composed of distinct or discontinuous elements.

From O.Fr. discret, from L. discretus "separated, distinct," from p.p. of discernere "to distinguish," from → dis- "off, away" + cernere "distinguish, separate, sift," → crisis.

Gosasté "broken, broken off," p.p. of gosastan "to break, split," Mid.Pers. wisistan "to break, split," Av. saed- "to split," asista- "unsplit, unharmed," Skt. chid- "to split, break, cut off," Gk. skhizein "to split," L. scindere "to split;" PIE stem *skei- "to split, cut."
Jodâ "separate, distinct," Mid.Pers. jutâk (yutâk), jut (yut).

The rapid, systematic changes in the absorption parts of the → P Cygni profiles of the ultraviolet → resonance lines (Si IV, C IV, and N V) observed in a majority of massive → hot stars. DACs are typically seen to accelerate to the → blue wing of the profile over a few days, becoming narrower as they approach the → terminal velocity.

→ discrete; → absorption; → component.

Data that can only take a small set of particular values, usually whole numbers. For instance, number of children in a family cannot be 2.4, since parents cannot actually have 2.4 children. → continuous data.

→ discrete; → data.

A localized source on the celestial sphere that can be observationally separated at radio wavelengths from its background emission.

→ discrete; → radio; → source.

A spectrum in which the component wavelengths (and wave numbers and frequencies) constitute a discrete sequence of values (finite or infinite in number) rather than a continuum of values.

→ discrete; → spectrum.

A transition between two quantum-mechanical energy levels. See also → discrete spectrum.

→ discrete; → transition.

A quantity that has certain magnitudes and does not represent a → continuous variable.

→ discrete; → value.

A variable which has only → discrete values and has no in-between values.

→ discrete; → variable.

A → quantum walk involving a probabilistic → operator that changes the direction while leaving the position fixed, and a shift operator that changes the position. Discrete-time quantum walk was introduced by J. Watrous (2001, Journal of Computer and System Sciences 62, 376)

→ discrete; → time; → quantum; → walk.