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Astronomy test 3
The unknown one
Question | Answer |
---|---|
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 |