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