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21 Cards in this Set

  • Front
  • Back
accretion disk
The whirling disk of gas that forms around a compact object such as a white dwarf, neutron star, or black hole as matter is drawn in. (p. 216)
angular momentum
A measure of the tendency of a rotating body to continue rotating. Mathematically, the product of mass, velocity, and radius. (p. 215)
black dwarf
The end state of a white dwarf that has cooled to low temperature. (p. 211)
Chandrasekhar limit
The maximum mass of a white dwarf, about 1.4 solar masses. A white dwarf of greater mass cannot support itself and will collapse. (p. 211)
degenerate matter
Extremely high-density matter in which pressure no longer depends on temperature due to quantum mechanical effects. (p. 204)
globular cluster
A star cluster containing 100,000 to 1 million stars in a sphere about 75 ly in diameter. Generally old, metal-poor, and found in the spherical component of the galaxy. (p. 208)
helium flash
The explosive ignition of helium burning that takes place in some giant stars. (p. 205)
horizontal branch
In the H-R diagram, stars fusing helium in a shell and evolving back toward the red giant region. (p. 209)
inner Lagrangian point
The point of gravitational equilibrium between two orbiting stars through which matter can flow from one star to the other. (p. 214)
Lagrangian points
Points of gravitational stability in the orbital plane of a binary star system, planet, or moon. (p. 214)
From the Latin, meaning "new," a sudden brightening of a star making it appear as a new star in the sky. Believed to be associated with eruptions on white dwarfs in binary systems. (p. 200)
open cluster
A cluster of 100 to 1000 stars with an open, transparent appearance. The stars are not tightly grouped. Usually relatively young and located in the disk of the galaxy. (p. 208)
planetary nebula
An expanding shell of gas ejected from a star during the latter stages of its evolution. (p. 207)
Roche lobe
The volume of space a star controls gravitationally within a binary system. (p. 214)
Roche surface
The dumbbell-shaped surface that encloses the Roche lobes around a close binary star. (p. 214)
The explosion of a star in which it increases its brightness by a factor of about a million. (p. 200)
supernova remnant
The expanding shell of gas marking the site of a supernova explosion. (p. 222)
synchrotron radiation
Radiation emitted when high-speed electrons move through a magnetic field. (p. 220)
turnoff point
The point in an H-R diagram at which a cluster's stars turn off of the main sequence and move toward the red-giant region, revealing the approximate age of the cluster. (p. 208)
type I supernova
A supernova explosion caused by the collapse of a white dwarf. (p. 220)
type II supernova
A supernova explosion caused by the collapse of a massive star. (p. 219)