Stars, Galaxies, and the Universe Flashcards
star
a large celestial body that is composed of gas and that emits light
Doppler effect
an observed change in the frequency of a wave when the source or observer is moving
light year
the distance that light travels in one year
parallax
an apparent shift in the position of an object when viewed from different locations
apparent magnitude
the brightness of a star as seen from the Earth
absolute magnitude
the brightness that a star would have at distance 32.6 light-years from Earth
main sequence
the location on the H-R diagram where most stars lie: it has a diagonal pattern from the lower right to the upper left
nebula
a large cloud of gas and dust in interstellar space:; a region in space where stars are born
giant
a very large and bright star whose hot core has used most of its hydrogen
white dwarf
a small, hot, dim star that is the leftover center of an old star
neutron star
a star that has collapsed under gravity to the point that the electrons and protons have smashed together to from neutrons
nova
a star that suddenly becomes brighter
pulsar
a rapidly spinning neutron star that emits pulses of radio and optical energy
black hole
an object so massive and dense that even light cannot escape its gravity
constellation
one of 88 regions into which the sky has been divided in order to describe that locations of celestial objects; a group of stars organized in a recognizable pattern
galaxy
a collection of stars, dust, and gas bound together by gravity
quasar
quasi-stellar radio source; a very luminous object that produces energy at a high rate
cosmology
the study of the origin, properties, processes, and evolution of the universe
cosmic background radiation
radiation uniformly detected from every direction in space; considered a remnant of the big bang 86
big bang theory
the theory that all matter and energy in the universe was compressed into an extremely small volume that 13 to 15 billion years ago exploded and began expanding in all directions
