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Astronomy Final
Last Chapters
38
Astronomy
Undergraduate 1
06/19/2011

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Term
What is Radiation?
Definition
The emission of energy as electromagnetic waves or as moving subatomic particles.
Term
What is the Stefan Boltzman Law?
Definition
The Stefan–Boltzmann law, also known as Stefan's law, states that the total energy radiated per unit surface area of a black body per unit time is directly proportional to the fourth power of the black body's thermodynamic temperature T 
Term
What is Wiens law?
Definition
the wavelength distribution of thermal radiation from a black body at any temperature has essentially the same shape as the distribution at any other temperature, except that each wavelength is displaced on the graph.
Term
What is blackbody?
Definition
idealized physical body that absorbs all incident electromagnetic radiation. Because of this perfect absorptivity at all wavelengths, a black body is also the best possible emitter of thermal radiation, which it radiates incandescently in a characteristic, continuous spectrum that depends on the body's temperature.
Term
What are the black body curves?
Definition
relationship between wavelength and the intensity of the light emitted bt a blackbody at a speceified temperature.
Term
What is spectroscopy?
Definition
all of the above
Term
What is the emissions spectrum?
Definition
series of bright lines on a dark background
Term
What is the absorbtion spectrum>?
Definition
a series of dark lines superimposed on the otherwise continuous spectrum
Term
If you were to look at spectrum through cold gas?
Definition
absorbtion spectrum
Term
Purpose of studying spectrum?
Definition

1) to identify the chemical composition of the star's atmosphere

2) to determine the surface temperature of the star

3) to determine the density of the radiating matter

Term
Illuminosity of star?
Definition
is the total amount of energy emitted into space each second from its surface
Term
What is absolute magnitude?
Definition
is the apparent brightness the star would have if it were placed at a distance of 10 parsecs
Term
A first magnitude is how many times brighter than 3rd magnitude star?
Definition
6.31 x brighter than 3rd magnitude star
Term
1.5, 3.3, 5.6, 17.2 which has highest apparent magnitude?
Definition
1.5
Term
g2, a6, k7, d3 hottest?
Definition
d3
Term
G0 G1 G2 G3 G4 G5 G6 hottest?
Definition
G0
Term
What is H-R diagram?
Definition
a plot of absolute magnitude vs. temperature
Term
most stars are member of what in H-R diagram?
Definition
main sequence
Term
when is approx pos of sun in H-R diagram?
Definition
winter
Term
right bottom corner are red dwarfs they are...
Definition
small, cool, dim
Term
below the diagnol belt are white dwarfs they are how small?
Definition
0.01 solar radiii
Term
What are red giants?
Definition
have radii 6 to 10 and 100 times that sun
Term
What is a double star?
Definition
a pair of stars bound by their mutual gravity and revolving around a common center of mass
Term
What is a supernova?
Definition
an extremely violent explosion that spreads the outer layers of a massive star into space
Term
age of universe?
Definition
12-18 billion yrs old
Term
what is the big bang?
Definition
a ball of infinite density exploded violently. This explosion hurling matter into the universe,
Term
What is a galaxy?
Definition
 A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
Term
hubbles laws?
Definition

recessional velocity of any galaxy is directly proportional to its distance from us.

 

v=hd

Term
what is neutrino?
Definition
massless particles that move at the spead of light, does not interact with matter
Term
Positron?
Definition
positively charged electrons
Term
How old is solar system?
Definition
4.5 billion years
Term
sun has been radiating energy for how long?
Definition
4.5 billion years
Term
for how much longer will sun radiate?
Definition
5 billion
Term
lifespan of solarsystem?
Definition
9.5 billion
Term
what is a black hole?
Definition
region of space whose gravitational pull is so strong that its escape veloicty equals the speed of light, preventing any radiation or material escaping its surface.
Term
dark matter?
Definition
used to describe the mass in galaxies that emits no detectable radiation but whose existence can be deduced by its gravitational attraction on other objects.
Term
what is luminosity measured in?
Definition
watts
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