Astronomy Notes

Flash cards from the notes of ch 11-15
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How are apparent brightness, luminosity, and distance related?
By the Inverse-square law
Which 2 characteristics are needed to determine a star's luminosity?
Distance, and apparent brightness
How do astronomers determine the distance of a star?
The most direct way is with stellar paralax.
what is the most common measurement of the paralax angle(p)?
Arcseconds
the farther a star is from us, the _____ the paralax angle.
smaller
as of 2010, what was the stellar distance limit?
a few hundred light years
if an object has a paralax angle of 1 arcsec, what is its distance?
1 parsec(pc)
what is the distance formula
d=1/p , where p is in arcsecs and d will come out in parsecs
P= .1 arcsecs, what is the distance.
1/p= 1/.1= 10 parsecs.
1 pc = ______ light years
3.26
we can use a star's ______ to determine its surface temp.
Thermal radiation spectrum
_____ gives an approximate range for surface temp.
Color
What is the acronym for the spectral types?
Oh be a fine goat, keep munching
What does "oh be a fine goat, keep munching" stand for/represent?
The spectral types
Our sun has a Spectral type of ____
G2
Spectral type is subdivided using a number 1-9, with lower numbers having _____ surface temp than higher numbers.
higher.
with spectral types, High number = ____________
Lower surface temperature
what happens in a binary stellar system?
2 stars orbit eachother
Mass of the sun is equal to _____
one solar mass
a typical white dwarf is about the size of _____, with the same mass as the _____.
Earth, sun
Duration as a mainstream star is also known as ______
Lifetime
our sun has a total lifetime of ________
10 billion years.
2 types of star clusters are________ and ________.
open, globular
the pre-stage to becoming a star is known as a ________
Protostar
if a protostar has a mass of less than ______ solar masses, it will NEVER become a main sequence star.
.08
efficient hydrogen fusion requires a minimum temp. of ______
10 million k
failed stars are known as _____
brown dwarfs
a sudden onset of helium core fusion, occuring for 1-2 solar mass MS stars is known as a_____
helium flash
Evidence of mass star supernova is kown as ________
supernova remants
the 3 possible stellar corpses are _________
White dwarfs, neutron stars, and black holes
white dwarfs are the stellar corpses of MS stars with masses ______
less than 8 solar masses
White dwarfs consist of mainly __ and ___
carbon, oxygen
if a white dwarf isnt in a (close) binary system, it will cool over a long period of time into a ____
black dwarf
if a white dwarf is in a (close) binary system, which 2 things can occur?
Nova, white dwarf supernova
Neutron stars are stellar corpses of Main sequence stars with masses in the range of ___ to___ solar masses
8,25
A Neutron star consists of _____
Neutrons
Density of a neutron star is much ____ than a White dwarf but much ___ than a black hole.
Greater,less
T or F- a Neutron star usually has a very strong magnetic field
TRUE
If a Neutron star is in a (close) binary system, then the companion star can create a ____ around the Neutron star.
Accretion disk
If a neutron star is rotating in an x-ray binary, the x-ray binary will pulsate rapidly, emitting bursts of higher intensity x-rays due to sudden fusion of helium. These bursts are called _____
x-ray bursters
The size of a Black hole is defined by the ____
schwarzschild radius
The radius of a white dwarf is determined by a balance between the inward force of gravity and the outward push of ________
Electron degeneracy pressure
A ___ occurs when hydrogen fusion ignites on the surface of a white dwarf in a binary system
nova
a ____ occurs when fusion creates iron in the core of a star
massive star supernova
a white dwarf in a close binary system will explode as a supernova if it gains enough mass to exceed the ____
white dwarf limit
a ________ consists of hot swirling gas, captured by a white dwarf (or nuetron star or BH) from a binary companion star.
accretion disk
A ____ can occur only in a binary system and all such events are thought to have the same luminocity.
White dwarf supernova
Where do gamma ray bursts tend to come from
Extremely distant galaxies
Where are most of milky ways globular clusters found?
in the halo
Where would be the most likely place to find an ionization nebula?
In a spiral arm
Which kind of star is most likely to be part of the shperoidal popluation? An O, A or M star?
An M star
We measure the mass of the BH at the galactic center from?
The orbits of stars in the galactic center
Which of these galaxies would you most likely find at the center of a large cluster of galaxies?
A large eliptical galaxy
Hubbles law expresses a relation between ____?
The distance of a galaxy and the speed at which it is moving away from us
Describe the meaning of Hubble's constant
It describes the expasion rate of the universe with higher vaules meaning more rapid expansion
Which kind fo object is the best standard candle for measuring distances to extremely distant galaxies?
A white dwarf supernova
____ have the highest rates of star formation
Star burst galaxies
The largest individual galaxies in the universe are known as ____
Central dominant galazies
The collective activity of many supernova events in a relatively small volume of a galaxiy can create __________
Galactic winds
the most luminous objects in the universe are ___
quasars
The energy for all active galactic nuclei is thought to come from in-fall of matter into ____
supermassive black holes
____ are often characterized by sources of emense energy located hundreds of thousands of light-years away on either side of their centers
Radio galaxies
The luminosity of a Quasar is generated in a region the size of ____
the solar system
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