| Mass of the Sun |
1.989 X 10^{33} gms. |
| Luminosity of the Sun |
3.93 X 10^{33} ergs/sec. |
| Radius of the Sun |
6.96 X 10^{10} cm. |
1 eV |
1.602 X 10^{-12} erg. |
E = kT |
1.380 X 10^{-23} T J = 8.617 X 10^{-5} T eV. |
E = hv |
4.136 X 10^{-15}v eV. |
1 light year |
9.4605 X 10^{17} cm. |
L_{Edd} |
1.3 X 10^{31} (M/M_sun) W. |
| 1 A. U. |
1.496 X 10^{13} cm. |
| 1 parsec |
3.085678 X 10^{18} cm. |
| 1 Jansky |
10^{-26} Watt m^{-2} Hz^{-1} |
| acceleration
disk |
A
sheet of gas and dust surrounding any massive object growing in size by
attracting material. |
| accretion
disk |
A disk shape
formed by gas as it spirals into a black hole. |
| atom |
The basic
unit of matter. |
| binary
star system |
A system in
which two stars orbit around a common center of mass. |
| black
hole |
A region of
space-time formed by the collapse of a massive object, such as a star.
A black hole is coined "black" because nothing, not even light,
can escape its grasp. |
| cosmic
censorship hypothesis |
States that
the singularities produced by gravitational collapse must be hidden behind
an event horizon. |
| Doppler
effect |
Relationship
between wavelength and speed where shifting of wavelength occurs when the
movement of an object is away or towards an observer. |
| Eddington
Luminosity |
The luminosity
at which the radiation pressure acting on the infalling gas is sufficient to
prevent the matter falling onto the surface of the compact object.
|
| event
horizon |
The
boundary of a black hole. The point of no return. |
| frame
dragging |
As
a black hole rotates, it drags space and time around itself. |
| general
relativity |
Albert
Einstein's theory that proposes that gravity is a curvature of four-dimensional
space-time caused by the presence of matter. |
| gravitation |
One
of the two main processes in a star in which hydrogen is pulled back to
the star's center. |
| gravitational
collapse |
When a massive
object collapses under its own weight. |
| gravity
lensing |
A
technique used to detect black holes. A black hole acts as a lens by bending
lights rays from a star and focusing them on the Earth. |
| Hawking
Radiation |
The positive
particle of a virtual particle pair released from the event horizon of
a black hole after the negative one is absorbed. |
| microquasar |
A black hole
system that has a stream of x-rays and blasts of radio-emitting gas. This
resembles a scaled down version of the action of quasars in distant galaxies. |
| no
hair theorem |
Theory
that states the size of a black hole depends only on its mass and rate
of rotation. |
| neutron
star |
The imploded
core of a star between 1.4 and 3 times the mass of a sun produced by a
supernova explosion. |
| nuclear
fusion |
One
of the two main processes in a star in which hydrogen is blown outward
from the star's center. |
| plasma |
A low-density
gas in which individual atoms are ionized. |
| precession |
A slow circular
motion about the lower vertical axis of an accretion disk. |
| primordial
black hole |
A black hole
formed in the early universe. |
| quantum
mechanics |
Conservation
of energy theory developed from Planck's quantun principle and Heisenberg's
uncertainty principle. |
| quasar |
A type of
a quasi-stellar object. |
| quasi-stellar
object |
A stellar-appearing
object of very large redshift that is a strong source of radio waves. |
| redshift |
Reddening
of light as it moves away from us, due to the Doppler effect. |
| singularity |
The
center of a black hole at which matter is crushed to an infinite density,
the pull of gravity is infinitely strong, and the space-time curvature
becomes infinitely large. |
Schwarzschild Radius
r_{g} = 2GM/c^{2} |
No radiation can escape from within this radius and hence the surface at
this radius is 'black'. |
| space-time |
Four-dimensional
space. |
| speed
of light |
The speed
at which light travels (186,282 miles per second). The distance light can
travel in one year is called a light year. |
| white
dwarf |
A
star less than 1.4 the mass of the sun that has exhausted all of its nuclear
fuel and has collapsed to a very small size. |
|
|
