Option D Definitions Flashcards
1
Q
Nebula
A
A vast cloud of dust and gas
2
Q
Radiation pressure
A
the pressure exerted by the photons, which result from the hydrogen to helium-4 fusion reaction, on the surrounding material as they slowly make their way out from the core.
3
Q
Gas pressure
A
Outwards pressure on surrounding material due to the kinetic energy of the gas particles that make up stars
4
Q
One astronomical unit (AU)
A
The average Earth-Sun distance; or, the radius of a circular orbit that would give the same year length as Earth’s elliptical orbit.
5
Q
Luminosity
A
Power of a star (rate at which it radiates energy)
6
Q
Apparent brightness (intensity)
A
Power of a star recieved by observer per unit area. Varies with distance
