Stars Vocabulary

star

a self-luminous object made of gas held together by its own gravity

luminosity

the total amount of energy emitted by a star per unit of time, indicating its brightness

H-R diagram

a graph that shows the relationship between a star's surface temperature and its luminosity

nebula

cloud of gas and dust in space where stars are formed

protostar

the second stage of a star's life cycle, a "baby" star

main sequence

stage of a star's life cycle represented by a diagonal area on an H-R diagram that currently includes more than 90 percent of all stars

red giant

the stage after the main sequence where the hydrogen supply has run out and the star begins to expand and die

planetary nebula

an expanding shell of gas surrounding a dying star

white dwarf

stage where gravity causes the last of the star's matter to collapse inward and compact

supernova

the explosion of a dying supergiant star

neutron star (pulsar)

an extremely dense star that may form after a supernova that emits electromagnetic waves

black hole

an object in space which has a gravitational pull that is so strong not even light can escape