Stars Flashcards
Define planet.
An object that orbits a star and must 1) Have a large enough mass for its own gravity give it a round shape, 2) have no fusion reactions, 3) Have cleared its orbits of most other objects.
Define planetary satellite.
A body in orbit around planet, including moons and man-made satellites.
Define comets.
Small, irregular bodies made up of dust, ice, and small pieces of rock, which orbit the sun in highly elliptical orbits.
Define the solar system.
A collective name for a star and all the objects that orbit that star, including planets, comets and asteroids.
Define a galaxy.
A collection of stars, interstellar dust and gas bound together by their mutual gravitational attraction.
Define Nebulae.
Huge clouds of dust and gas, mainly hydrogen, Singular version is nebula plural version is nebulae.
Define a protostar.
A very hot and dense sphere of dust and gas that is comes before a star formation. Not all protostars starts nuclear fusion to become stars.
Define Solar mass.
Mass of the sun 1.99x10^30kg.
Define a low mass star.
Stars with masses between 0.5-10 solar masses.
Define a Red Giant.
An expanding star that has an inert core with no fusion taking place, but a shell around the core in which light elements are undergoing fusion.
Define a White Dwarf.
A very dense inert core (no fusion taking place) of a red giant, left over when the outer layers of the red giant have been pushed away.
Define the Chandrasekhar limit.
The mass of star’s core below which the electron degeneracy pressure will prevent gravitational collapse. The Chandrasekhar limit is 1.44 solar masses.
Define massive stars.
Stars with masses greater than 10 solar masses.
Define Red supergiant.
A massive star in the last stages of its life. Fusion of elements larger than hydrogen are taking place inside the star’s core.
Define a Supernova.
An implosion of a red supergiant following the formation of sufficient iron in its core. The outer core and outer layers bounce off the inner core and are ejected into space, leaving an inert remnant core.
