An Etymological Dictionary of Astronomy and Astrophysics
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A curve, on the pressure versus specific volume plane, representing the locus of all the possible states that can be reached by a substance immediately after the passage of a single → shock wave. For each initial condition there is a different curve. No combustion occurs in the process and, therefore, the chemical composition of the medium does not change. See also → Rayleigh line; → Crussard curve.

Named after the French physicist Pierre Henri Hugoniot (1851-1887), who worked on fluid mechanics, especially flow properties before and after shock waves; → curve.

A graph showing the relation between → interstellar absorption (in magnitudes) and wavelength.

→ interstellar; → reddening; → curve.

A → rotation curve in which the speed of the orbiting body is inversely proportional to the → square root of its distance from the mass concentrated at the center of the system.

→ Keplerian; → rotation; → curve.

1) A curve showing the behavior of the light from a → variable star over a period of time.
2) → supernova light curve.

→ light; → curve.

The photometric variability induced by the → orbital motion in a → two-body system.

→ orbital; → phase.

1) Astro.: A curve describing the → brightness of a reflecting → natural satellite as a function of its → phase angle.
2) Math.: A plot of the solution to a set of equations of motion in a phase space as a function of time.

→ phase; → curve.

Same as → blackbody curve.

→ Planck; → curve.

A plot that displays the → potential energy of a moving body as a function of its position. It is explained by the → conservation of energy and the conversion of potential energy into → kinetic energy and vice versa.

→ potential; → energy; → curve.

A curve that describes the distribution of probability over the values of a random variable.

→ probability; → curve.

A curve describing the variation of the radial velocity of a star, due to the Doppler effect, under the gravitational effect of a secondary body (companion or exoplanet). The amplitude of these variations depends upon the mass of the secondary and its distance from the star.

→ radial velocity; → curve.

A curve representing a non-linear relationship between two or more → variables.

→ regression, → curve.

A curve graphically representing the magnitude of the → response of a → detector to → radiation, usually as a function of → wavelength.

→ response; → curve.

A plot of the variation in → orbital velocity of stars and → interstellar matter with distance from the center of a → galaxy. A "flat" rotation curve indicates that the mass of the galaxy increases linearly with distance from its center. See also: farsi→ Keplerian rotation curve

Rotation; → curve.

1) A curve which is free from abrupt fluctuations.
2) A curve if it has tangents at all points and the angle of inclination of the tangent is a continuous function of the arc length.

→ smooth; → curve.

The graph of luminosity as a function of time after a → supernova explosion. The → light curve goes up rapidly to a → peak luminosity, then decays away slowly over time, with different rates, depending on the → supernova type. The temporal evolution of a supernova's luminosity contains important information on the physical processes driving the explosion. The observed → bolometric light curves provide a measure of the total output of converted radiation of → Type Ia supernovae, and hence serve as a crucial link to theoretical models of the explosion and evolution.

→ supernova; → light; → curve.

A plot of the radial velocity of an object against time, derived from the Doppler shift of spectral lines.

→ velocity; → curve.