Black Holes and Neutron Stars
speed of light
3.00 x 10^8 m/s
tidal forces
Change in the strength of gravity across an object. Moon;s pull on earth is stronger on part closest to moon and weaker on the farther part. This stretches Earth. (tidal bulge)
x-rays
Electromagnetic radiation having a very short wavelength; can penetrate substances such as skin and muscle.
gamma rays
Electromagnetic waves with the shortest wavelengths and highest frequencies; generated by radioactive atoms in nuclear explosions. Some doctors use these waves to kill cancer cells.
gravity
Force of attraction between objects
supermassive black hole
Giant black hole, with a mass millions to billions of times that of our Sun, thought to reside in the centers of many galaxies and to power active galactic nuclei.
type II supernova
Hydrogen-rich, core-collapse supernova, high mass star
core
Left for black hole of neutron star after a type II supernova
binary system
Most common star system, where two stars orbit each other.
neutrons
Small uncharged particles that are found in the nucleus of an atom
spacetime
The four-dimensional continuum in which all events take place and all things exist. Three dimensions are the coordinates of space, and the fourth is time.
lighthouse model
The leading explanation for pulsars. A small region of the neutron star, near one of the magnetic poles, emits a steady stream of radiation that sweeps past Earth each time the star rotates. The period of the pulses is the star's rotation period.
general relativity
The more mass you have, the more your gravitational field curves spacetime. So while you're closer to a massive object, like the Earth, because mass is equivalent to energy, time will move more slowly for you. This is just like how time moves more slowly when you are going fast, because you have lots of energy.
neutron star
a celestial object of very small radius (typically 18 miles/30 km) and very high density, composed predominantly of closely packed neutrons. Neutron stars are thought to form by the gravitational collapse of the remnant of a massive star after a supernova explosion, provided that the star is insufficiently massive to produce a black hole.
pulsar
a celestial object, thought to be a rapidly rotating neutron star, that emits regular pulses of radio waves and other electromagnetic radiation at rates of up to one thousand pulses per second.
black hole
final stage in the evolution of a very massive star, where the core's mass collapses to a point that its gravity is so strong that not even light can escape
hypernova
produced when very massive star collapses in black hole, thought be possible source of gamma ray burts
event horizon
the location around a black hole where the escape velovity equals the speed of light; the boundary of a black hole
special relativity
the theory that, in an inertial frame of reference, the motion of an object is relative to the frame from which it is viewed or measured
