Astronomy Unit 6 Flashcards
the upper limit to the mass of a white dwarf (equals 1.4 times the mass of the Sun)
Chandrasekhar limit
a gas that resists further compression because no two electrons can be in the same place at
the same time doing the same thing (Pauli exclusion principle)
degenerate gas
a pulsar that rotates so quickly that it can give off hundreds of pulses per second (and its
period is therefore measured in milliseconds)
millisecond pulsar
a compact object of extremely high density composed almost entirely of neutrons
neutron star
the cataclysmic explosion produced in a binary system, temporarily increasing its luminosity by hundreds to thousands of times
nova
a variable radio source of small physical size that emits very rapid radio pulses in very regular periods that range from fractions of a second to several seconds; now understood to be a rotating, magnetic neutron star that is energetic enough to produce a detectable beam of radiation and particles
pulsar
a stellar explosion produced at the endpoint of the evolution of stars whose mass exceeds
roughly 10 times the mass of the Sun
type II supernova
the disk of gas and dust found orbiting newborn stars, as well as compact stellar remnants
such as white dwarfs, neutron stars, and black holes when they are in binary systems and are sufficiently close to their binary companions to draw off material
accretion disc
a region in spacetime where gravity is so strong that nothing—not even light—can escape
black hole
concept that a gravitational force and a suitable acceleration are indistinguishable
within a sufficiently local environment
equivalence principle
a boundary in spacetime such that events inside the boundary can have no effect on the world
outside it—that is, the boundary of the region around a black hole where the curvature of spacetime no longer provides any way out
event horizon
Einstein’s theory relating gravity and the structure (geometry) of space and time
general theory of relativity
an increase in wavelength of an electromagnetic wave (light) when propagating from
or near a massive object
gravitational redshift
a disturbance in the curvature of spacetime caused by changes in how matter is distributed; gravitational waves propagate at (or near) the speed of light
gravitational wave
the point of zero volume and infinite density to which any object that becomes a black hole must
collapse, according to the theory of general relativity
singularity
