very large star of high luminosity and low surface temperature, thought to be in a late stage of evolution when no hydrogen remains in the core to fuel nuclear fusion.

extremely large red giant star with a minimum of 15 solar masses. The best known red supergiant is Betelgeuse, with a luminosity about 10,000 times that of the Sun.

star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass.

a celestial object of very small radius and very high density, composed predominantly of closely packed neutrons, thought to form by the gravitational collapse of the remnant of a massive star after a supernova explosion

a region of space having a gravitational field so intense that no matter or radiation can escape.

INFORMAL

a measure of the amount of matter in an object.

the intrinsic brightness of a celestial object

is the force by which a planet or other body draws objects toward its center

Any of a large group of elements, including iron, gold, copper, lead, and magnesium, that conduct heat and electricity well.

involves the combining of several small nuclei into one large nucleus with the subsequent release of huge amounts of energy.

stars with masses less than half the mass of the Sun) are the smallest, coolest and dimmest Main Sequence stars and orange, red or brown in color.