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star ![click to hear : star click to hear : star](../../images/speaker-vert.gif)
A sphere of gas massive enough to generate light and heat through nuclear reactions that transform hydrogen into helium in its core.
brown dwarf ![click to hear : brown dwarf click to hear : brown dwarf](../../images/speaker-vert.gif)
Star whose mass is not sufficient to generate a nuclear reaction.
main-sequence star ![click to hear : main-sequence star click to hear : main-sequence star](../../images/speaker-vert.gif)
Star whose mass is sufficient to generate a nuclear reaction.
planetary nebula ![click to hear : planetary nebula click to hear : planetary nebula](../../images/speaker-vert.gif)
Expanding gaseous envelope that corresponds to the external layer of a red giant that is gradually fading away.
black dwarf ![click to hear : black dwarf click to hear : black dwarf](../../images/speaker-vert.gif)
Dead star, likely the residue of a dwarf that has totally exhausted its energy resources.
low-mass stars ![click to hear : low-mass stars click to hear : low-mass stars](../../images/speaker-vert.gif)
Stars whose mass is less than 1.5 times that of the Sun.
red giant ![click to hear : red giant click to hear : red giant](../../images/speaker-vert.gif)
An old star whose hydrogen reserve has been exhausted; its luminosity can be 100 times that of the Sun.
white dwarf ![click to hear : white dwarf click to hear : white dwarf](../../images/speaker-vert.gif)
An old, extremely dense star of faint luminosity, formed by the nucleus of a red giant contracting until it reaches the size of Earth.
nova ![click to hear : nova click to hear : nova](../../images/speaker-vert.gif)
A white dwarf that assimilates gaseous matter from a neighboring star, suddenly becoming extremely bright before it returns to its initial brightness.
massive stars ![click to hear : massive stars click to hear : massive stars](../../images/speaker-vert.gif)
Stars whose mass is more than 1.5 times that of the Sun; can be up to 50 times the mass of the Sun.
supergiant ![click to hear : supergiant click to hear : supergiant](../../images/speaker-vert.gif)
An old, extremely luminous star of considerable mass; its diameter can be as much as 100 times that of the Sun.
neutron star ![click to hear : neutron star click to hear : neutron star](../../images/speaker-vert.gif)
Star formed of compressed neutrons, believed to be the residue of a supernova explosion.
supernova ![click to hear : supernova click to hear : supernova](../../images/speaker-vert.gif)
A supergiant that collapses onto itself and explodes with such force that it releases more energy than millions of suns.
pulsar ![click to hear : pulsar click to hear : pulsar](../../images/speaker-vert.gif)
A neutron star that rotates rapidly on itself, thereby emitting regular radio waves.
black hole ![click to hear : black hole click to hear : black hole](../../images/speaker-vert.gif)
Results when the core of a massive star collapses; the gravitational force is so strong that not even light can escape.