DICTIONARY OF GEOPHYSICS, ASTROPHYSICS, and ASTRONOMY

case 1 water Water whose optical properties
are determined primarily by phytoplankton and
co-varying colored dissolved organic matter and
detritus; not a synonym for open ocean waters.
case 2 water Water whose optical properties
are significantly influenced by colored dissolved
organic matter, detritus, mineral particles, bubbles,
or other substances whose concentrations
do not co-vary with the phytoplankton concentration;
not a synonym for coastal waters.
Cassegrainian A type of reflecting telescope
invented by G. Cassegrain, with a small convex
secondary mirror mounted in front of the primary
mirror, to reflect rays approaching a focus
back through a hole in the primary mirror, where
they are viewed using a magnifying lens (eyepiece)
from behind the telescope.
Cassini A spacecraft destined for Saturn that
was launched on October 15, 1997, and is expected
to arrive in July 2004. At this time, it will
orbit Saturn for four years. It is a joint mission
of NASA, the European Space Agency (ESA),
and the Italian Space Agency. The spacecraft
consists of an orbiter and ESA’s Huygens Titan
probe. The latter will be dropped through
the atmosphere to the surface of Saturn’s largest
moon, Titan.
In total the spacecraft weighs 5650 kg. In
order to get to Saturn in the nominal 6 years and
9 months, it was initially launched inward, not
outward, and aimed toward Venus rather than
Saturn, to provide a “gravity-assisted” trajectory.
This consists of two Venus flybys, a flyby
of Earth, and a flyby of Jupiter.
The mission is named in honor of the
seventeenth-century, French-Italian astronomer
Jean Dominique Cassini, who discovered the
prominent gap in Saturn’s main rings, as well
as four icy moons. The Titan probe is named in
honor of the Dutch scientist Christiaan Huygens,
who discovered Titan in 1655, and realized that
the strange Saturn “moons” seen by Galileo in
1610 were a ring system surrounding the planet.
Cassini’s division A gap, detectable by small
telescope observation, between the A and B
rings of Saturn, discovered by Cassini.
© 2001 by CRC Press LLC
cataclysmic variable (cataclysmic binary)
Cassiopeia A A discrete strong radio source
at RA 23 h 21 m 10 s , dec +58 o 32 ′ 05 ′′ emitting 21cm
radiation. Cas A was apparently created in
a supernova explosion in 1667. The constellation
Cassiopeia is located almost directly opposite
the Big Dipper across the north celestial
pole. Five bright stars in the constellation form
a rough W (or M) in the sky. (Tycho’s supernova
also appeared in the constellation in 1572
and disappeared in 1574.)
Castor Double star (alpha Geminorum A,
B). A is an A1 type 1.94 magnitude star located
at RA 07 h 34.4 m , dec +31 ◦ 54 ′ ; B is a type A2,
2.92 magnitude star located at RA 07 h 34.5 m ,
dec +31 ◦ 54 ′ .
Castor, John I. Astrophysicist. In 1976, in
collaboration with David Abbott and Richard
Klein, developed the theory of winds in early
type stars (CAK theory). Through hydrodynamic
models and atomic data, they showed that
the total line-radiation pressure is the probable
mechanism that drives the wind in these systems,
being able to account for the observed
wind speeds, wind mass-loss rates, and general
form of the ultraviolet P-Cygni line profiles
through which the wind was originally detected.
cataclysmic variable (cataclysmic binary)
A star that suddenly and unpredictably brightens
by several magnitudes, most likely by a transfer
of stellar material from one star to its close
companion. A few weeks or so after the eruptive
event, the star returns to its original brightness,
indicating that a permanent transformation
or evolution of the system has not taken
place. Stars exhibit some or all of the following
characteristics: flat or blue optical spectral
distribution, broad emission or absorption
lines of hydrogen and helium, rapid variability,
marked aperiodical changes in optical brightness,
and low X-ray luminosity. Binary star
in which one component is a white dwarf and
one is a main sequence star or red giant, where
the stars are close enough together that material
flows onto the white dwarf from its companion,
either through Roche Lobe overflow or in
a stellar wind. Pairs without such transfer are
called V471 Tauri stars. Mass transfer at a rate
of 10 −7−8 solar masses per year is relatively sta-