Ch. 25 Vocabulary
Terms in this set (20)
an apparent group of stars originally named for mythical characters; The sky is presently divided into 88 constellations.
one of two stars revolving around a common center of mass under their mutual gravitational attraction.
the distance light travels in a year, about 9.5 trillion kilometers.
the brightness of a star when viewed from earth.
the apparent brightness of a star if it were viewed from distance of 32.6 light-years; used to compare the true brightness of stars.
a star that falls onto the main-sequence category on the H-R diagram; This category contains the majority of stars and runs diagonally from the upper left to the lower right on the H-R diagram.
a large, cool star of high luminosity; a star occupying the upper-right portion of H-R diagram.
a very large, very bright red giant star.
a star whose brightness varies periodically because it expands and contracts; a type of pulsating star.
a star that explosively increases in brightness.
a collapsing cloud of gas and dust destined to become a star; a developing star not yet hot enough to engage in nuclear fusion.
an exploding star that increases in brightness many thousands of times.
a star that has exhausted most or all of its nuclear fuel and has collapsed to a very small size, believed to be near its final stage of evolution.
a star of extremely high density composed entirely of neutrons.
a variable radio source of small size that emits radio pulses in very regular periods.
a massive star that has collapsed to such a small volume that its gravity prevents the escape of everything, including light.
a group of stars, dust, and gases held together by gravity.
a system of galaxies containing from several to thousands of member galaxies.
a law that states that the galaxies are retreating from the Milky Way at the speed that is proportional to their distance.
Big Bang theory
a theory that proposes that the universe originated as a single mass, which subsequently exploded.