An Etymological Dictionary of Astronomy and Astrophysics

The observed peculiar velocities of galaxies in the → redshift space of → galaxy clusters when the galaxies undergo → infall toward a central mass.
This → redshift space distortion differs from the → fingers of God in that the peculiar velocities are not random, but correspond to the coherent falling of galaxies toward the central mass. See also → peculiar velocity.

See also: Kaiser, N., 1987, MNRAS 227, 1; → effect.

The observed peculiar velocities of galaxies in the → redshift space of → galaxy clusters when the galaxies undergo → infall toward a central mass.
This → redshift space distortion differs from the → fingers of God in that the peculiar velocities are not random, but correspond to the coherent falling of galaxies toward the central mass. See also → peculiar velocity.

See also: Kaiser, N., 1987, MNRAS 227, 1; → effect.

The hypothesis of the origin of the solar system proposed first by Kant (1755) and later by Laplace (1796). According to this hypothesis, the solar system began as a nebula of tenuous gas. Particles collided and gradually, under the influence of gravitation, the condensing gas took the form of a disk. Larger bodies formed, moving in circular orbits around the central condensation (the Sun).

See also: Named after the German prominent philosopher Immanuel Kant (1724-1804) and the French great mathematician, physicist, and astronomer Pierre-Simon Marquis de Laplace (1749-1827); → hypothesis.

The hypothesis of the origin of the solar system proposed first by Kant (1755) and later by Laplace (1796). According to this hypothesis, the solar system began as a nebula of tenuous gas. Particles collided and gradually, under the influence of gravitation, the condensing gas took the form of a disk. Larger bodies formed, moving in circular orbits around the central condensation (the Sun).

See also: Named after the German prominent philosopher Immanuel Kant (1724-1804) and the French great mathematician, physicist, and astronomer Pierre-Simon Marquis de Laplace (1749-1827); → hypothesis.

Any of a group of four short-lived → mesons distinguished by a → quantum number called → strangeness. Also called K meson and denoted K. They are positive, negative, or neutral and have a mass of about 495 MeV/c (about 970 times that of an → electron).

See also: Kaon, from ka (for the letter K) + (mes)on, → meson.

Any of a group of four short-lived → mesons distinguished by a → quantum number called → strangeness. Also called K meson and denoted K. They are positive, negative, or neutral and have a mass of about 495 MeV/c (about 970 times that of an → electron).

See also: Kaon, from ka (for the letter K) + (mes)on, → meson.

A process based on the effects of → opacity (κ) that drives the → pulsations of many types of variable stars. Consider a layer of material within a star and suppose that it undergoes inward contraction. This inward motion tends to compress the layer and increase the density. Therefore the layer becomes more opaque (See also → partial ionization zone). If a certain amount of flux comes from the deeper layers it gets stuck in the high κ region. The energy accumulates and heat builds up beneath it. The pressure rises below the layer, pushing it outward. The layer expands as it moves outward, cools and becomes more transparent to radiation. Energy can now escape from below the layer, and pressure beneath the layer diminishes. The layer falls inward and the cycle repeats. The κ mechanism is believed to account for the pulsations of several star families, including → Delta Scuti stars, → Beta Cephei variables, → Cepheids, and → RR Lyrae stars
(See Baker & Kippenhahn, 1962, Zeitschrift für Astrophysik 54, 114). Same as
κ effect and → valve mechanism. See also → gamma mechanism.

See also: κ, the Gk. letter which denotes opacity; → mechanism.

A process based on the effects of → opacity (κ) that drives the → pulsations of many types of variable stars. Consider a layer of material within a star and suppose that it undergoes inward contraction. This inward motion tends to compress the layer and increase the density. Therefore the layer becomes more opaque (See also → partial ionization zone). If a certain amount of flux comes from the deeper layers it gets stuck in the high κ region. The energy accumulates and heat builds up beneath it. The pressure rises below the layer, pushing it outward. The layer expands as it moves outward, cools and becomes more transparent to radiation. Energy can now escape from below the layer, and pressure beneath the layer diminishes. The layer falls inward and the cycle repeats. The κ mechanism is believed to account for the pulsations of several star families, including → Delta Scuti stars, → Beta Cephei variables, → Cepheids, and → RR Lyrae stars
(See Baker & Kippenhahn, 1962, Zeitschrift für Astrophysik 54, 114). Same as
κ effect and → valve mechanism. See also → gamma mechanism.

See also: κ, the Gk. letter which denotes opacity; → mechanism.

A way of measuring a civilization’s technological advancement based upon how much usable energy it has at its disposal.

The scale was originally designed in 1964 by the Russian astrophysicist Nikolai Kardashev (who was looking for signs of extraterrestrial life within cosmic signals). It has three base classes, each with an energy disposal level: Type I, Type II, and Type III.

Type I designates a civilization that is capable of controlling the total energy of its home planet (10¹⁶ watts).

Type II is an interstellar civilization, capable of harnessing the total energy output of a star (10²⁶ W).

And Type III represents a galactic civilization, capable of inhabiting and harnessing the energy of an entire galaxy (10³⁶ W).

The scale has since been expanded by another four.
Type 0 is civilization that harnesses the energy of its home planet, but not to its full potential. The Earth civilization is currently at about 0.73 on the Kardashev scale.

See also: The scale was originally designed in 1964 by the Russian astrophysicist Nikolai Kardashev (1932-); → scale.

A way of measuring a civilization’s technological advancement based upon how much usable energy it has at its disposal.

The scale was originally designed in 1964 by the Russian astrophysicist Nikolai Kardashev (who was looking for signs of extraterrestrial life within cosmic signals). It has three base classes, each with an energy disposal level: Type I, Type II, and Type III.

Type I designates a civilization that is capable of controlling the total energy of its home planet (10¹⁶ watts).

Type II is an interstellar civilization, capable of harnessing the total energy output of a star (10²⁶ W).

And Type III represents a galactic civilization, capable of inhabiting and harnessing the energy of an entire galaxy (10³⁶ W).

The scale has since been expanded by another four.
Type 0 is civilization that harnesses the energy of its home planet, but not to its full potential. The Earth civilization is currently at about 0.73 on the Kardashev scale.

See also: The scale was originally designed in 1964 by the Russian astrophysicist Nikolai Kardashev (1932-); → scale.