5.5.1: Stars Flashcards
(18 cards)
Planet
An object that orbits a star and:
1) has enough mass to form a sphere under its own gravity
2) has no fusion reactions
3) has cleared is orbit of most other objects
Planetary satellite
A body in orbit around a planet
Comets
Small, irregular bodies made of dust, ice and small pieces of rock which orbit the sun in highly elliptical orbits
Solar system
A collective name for a star and all the objects that orbit that star, including planets, comets and asteroids
Galaxy
A collection of stars, interstellar dust and gas
Universe
Everything, from matter to energy to all of space-time
Nebulae
Huge clouds of dust and gas, mainly hydrogen
Protostar
A very hot and dense sphere of dust and gas that is the precursor to a star. Not all protostars start nuclear fusion and become stars
Solar mass
The mass of our Sun
Low mass stars
Stars between 0.5 and 10 solar masses
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
White dwarf
A very dense inert core (no fusion) of a red giant, left over when the outer layers of the red giant have been pushed away
Chandrasekhar limit
The mass of a star’s core below which electron degeneracy pressure will prevent gravitational collapse. 1.44 solar masses
Massive stars
Stars with a mass > 10 solar masses
Red supergiant
A massive star in the last stages of its life. Fusion of elements heavier than hydrogen are taking place inside the star’s core
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
Neutron star
Following a supernova, if the remnant core has 1.44 < mass < 3 then a neutron star is formed after gravitational collapse. A neutron star consists almost entirely of neutrons and is extremely dense
Black hole
Following supernova, if the remnant core is above 3 solar masses, then gravitational collapse continues until the escape velocity is greater than the speed of light.
