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Describe the In transit theory
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Name some problems with the in transit theory
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Astronomy test 3

The unknown one

QuestionAnswer
Describe the In transit theory God made the light waves closer to us than the astronomical object
Name some problems with the in transit theory Most observable events never happened - doesn't explain redshifts or CMB - Untestable
Decay in the speed of light CDK
The CDK theory says the speed of light was much greater in the past
Problems with the CDK theory are Early data has large error bars - people would look for data to match a prediction - changing speed of light changes the nature of space
The heating theory says Starlight heats gas and dust in the galaxy to a temperature of several thousand kelvin in thousands of years
Name some problems with the heating theory Background radiation is smooth - starlight has many orders of magnitude, so why is CBM so smooth
Baryonic matter Matter we can interact with
Baryonic matter makes up __% of all matter 4
___________ physics says space isn't fixed Carmelian
___________ physics says space is fixed Neutonian
The orbit of _____________ was an issue for astronomers. Mercury
___________ physics does not need to invoke ________ Carmelian...Dark matter
In 1996, ________ predicted accelerating universe Carmei
We can find distance with Parallax
the distance at which 1 AU subtends an angle of 1 arc second Parsec
Define a parsec the distance at which 1 AU suptends an angle of 1 arc second
_______________ is the angle by which an object motions moves in an arc second subtending
1/parsecs distance
as stars get closer, the parallax angle gets larger
a ____________ arcsecond is 1/3600 of a degree arcsecond
there are ____ lightyears per parsec 3.26
the nearest star to the sun is Proxima Centauri (the system it is in is Alpha Centauri complex)
The two components of star movement are radial and transverse
The component of star movement that doppler shift measures is radial motion
Proper motion is used to measure the transverse motion
_________ star has the largest proper motion of any Bernard's star
The measure of the total power radiated by a star Luminosity or total brightness
Light drops off over distance
Apparent brightness is proportional to luminosity/distance^2
Apparent luminosity is measured using a __________ scale, which is related to our perception magnitude
Concerning apparent luminosity, _________ magnitudes are dimmer larger
__________ is a star large enough for us to image directly Betelguese
For stars that cannot be imaged directly, size must be calculated from luminosity and temperature
Luminosity is proportiional to radies^2 * temperature^4
The radiation from stars is blackbody radiation
The 7 general categories of stellar spectra are OBAFGKM
Finding the stars spectral type reveals its temperature
stars with low temperatures and high luminosity are giants and supergiants
high temperature and low luminosity white dwarfs
main sequence stars are fusing __________ into ____________ in their cores Hydrogen into helium
Luminous main sequence stars are hot (blue)
less luminous stars are cooler (yellow or red)
Nuclear fusion requires that ____________________ get close enough to each other to fuse Like charged Nlei
Nuclear fusion can only happen if the temperature is over 10 million K
The process that powers most stars is 1) two protons fuse to deuterons 2) two deuterons have a proton added to them to make helium 3 3) two helium 3s add together to make helium 4
Hot blue stars are (larger/smaller) than cool red ones larger
In order to balance gravity, the core temperature of a high mass star must be higher
A higher core temperature leads to more luminosity
______________________ can extend the cosmic distance scale to several thousand parsecs Spectroscopic parallax
Spectroscopic parallax can only happen if the star is on main sequence
we can measure mass using binary stars
two stars orbiting a center of mass around each other binary stars
name the 3 types of binary stars Visual - eclipsing binary - spectroscopic binary
we can measure ___________ binary stars by measuring brightness over time eclipsing
We can measure ____________ binary stars using Doppler shifts spectroscopic binary
we measure _______ with gravity mass
Most massive stars are _____ times mass of sun, least massive stars are ______ times mass of sun 100 times... .08 times
Sun's life expectancy is 10 billion years
atoms and small molecules, mostly hydrogen and helium gas
absorbs light and reddens light that does get through dust
general term for fuzzy objects in sky nebula
A dust group that absorbs visible radiation and emits radio radiation dark nebula
dust cloud glows due to hot stars emission nebula
Nebula which scatters blue light Reflection nebula (reflect light)
emission nebulae are made of hot, thin gas (exhibits distinct emission lines)
The most prominent emission line from emission nebulae is the H(alpha) line at hydrogen
Stars within nebulae cause dust and gas to evaporate (light hitting dust particles)
The average temperature of dark nebulae is a few tens of kelvins
dark nebulae absorb ______ and emit _______ light and emit radio waves
one particularly distinct dark nebula is the horsehead nebula
the ________ line is the line at which dark nebula emit low energy radiation 21cm
some molecules used to study dust clouds are
The formation of stars goes dust cloud, cloud collapses, forms a disk, planets form, solar systems form
as the dust cloud collapses, the cloud breaks into parts, which then fragment
when stuff falls through disksa nd into stars, this is called accretion
T tauri stars undergo magnetospheric accretion
In stage 1 of star formation cloud stars to collapse
for a star to form, ________ must overcome the force of _____________ Gravity, thermal pressure
When a dust cloud is collapsing, the cloud prevents a pressure buildup by converting _______ energy into _______________ thermal energy into infrared and radio photons
Stage 2 of star formation is cloud fragments begin to collapse
stage 3 of star formation is the interior of the fragment has begun heating and is 10,000K
In stage 3 of star formation, collisions with particles in the cloud, cause it to flatten into a disk
When, during star formation, the star first appears on the H-R diagram, it is a protostar
Stage 4 of star formation is the core of the cloud fragment is a protostar
Stage 5 of star formation is Protostars luminosity decreases as temperature rises
Stage 6 of star formation is core reaches 10MillionK, nuclear fusion beings, now a star
Stage 7 of star formation is star has reached main sequence, remains until hydrogen burns out
If the mass of the original star is not enough, it becomes a failed brown dwarf
True or false: when photons strike matter, they exert pressure? true
If a star is more massive than ______ it blows apart, if it is less massive than _____ it can't sustain fusion 300Msun, .08Msun
Star clusters are the best way to study star formation since the only variable factor is mass
The two types of star clusters are open and globular
Open star clusters are young, loose, sparsely packed, in galactic plane
Globular star clusters are old, strongly bound, mostly in halo, densely packed
When a star leaves main sequence, what it becomes is based on its mass
when a star leaves main sequence, if it has high mass it __________ if it has low mass it __________ explode...die out
Stage 8, the star is a subgiant
stage 9, the star is a red giant
Stage 10, we achieve helium fusion
When the core reaches 10^8, what happens all of the helium in the core fuses within hours.
helium fuses to carbon and oxygen
After a helium flash, the star becomes a red giant again, with 2 shells
Stage 11 the star moves back to the giant branch
stage 12 the star is a nebula
a nebula has 2 parts a core and an envelop
stages 13 and 14 are white and brown dwarves
white dwarfs are the remaining core of dead stars
the white dwarf limit is 1.4Msun
When a white dwarf in a binary star pair gets hot enough, a nova forms (due to the accretion disk heating up)
A supernova happens when an 8 solar mass star cools off
a supernova is ______ times more luminous than a nova a million
the two types of supernova are carbon detonation and death of a high mass star
a carbon detonation supernova happens when a white dwarf accumulates too much mass
Created by: 100000077066708
 

 



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