Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Astro final study
Study guide posted by instructor
| Question | Answer |
|---|---|
| 1 step of proton-proton chain | 2 hydrogen fuse to heavy hydrogen |
| 2 step of proton-proton chain | 1 hydrogen and 1 heavy hydrogen fuse to helium isotope |
| 3rd step of proton-proton chain | 2 helium isotopes fuse to form helium and two hydrogen |
| 2 step of proton-proton chain | 1 hydrogen and 1 heavy hydrogen fuse to helium isotope |
| How long until Sun burns all of its hydrogen and runs out of fuel? | 10 billion years |
| How long does a star the size of the Sun stay on the main sequence? | 10 billion years |
| Where are granules located? | Red, emission from hydrogen |
| Convective zone--what's its location and how is energy transfered? | Near the surface, transported by convection |
| What is the Sun's chromosphere? | Upper atmosphere |
| What is Sun's photosphere? | Sun's visible surface, where gases change from opaque to transparent |
| How hot is the chromosphere? | 4500 Kelvin |
| How hot is the photosphere? | about 5800 Kelvin |
| What is luminosity determined by? | Red, from red emission of hydrogen |
| How hot is the photosphere? | about 5800 Kelvin |
| Where are spicules located? | Chromosphere |
| What is the Sun's chromosphere? | Upper atmosphere |
| What is the relationship between the Sun's corona and its solar wind? | Sun's photosphere |
| How hot is the chromosphere? | 4500 Kelvin |
| What color is the chromosphere and why? | Red, from red emission of hydrogen |
| How hot is the chromosphere? | 4500 Kelvin |
| A smaller magnitude indicates a ____ star and a higher magnitude indicates a ____ star. | brighter; dimmer |
| What color is the chromosphere and why? | Chromosphere |
| Apparent magnitude depends on _____ and _____. | luminosity; distance |
| What does luminosity measure? | Star's rate of fuel consumption, radius, and distance |
| A smaller magnitude indicates a ____ star and a higher magnitude indicates a ____ star. | brighter; dimmer |
| A star's spectral type is based on the appearance of ________ | Spectrum lines |
| Magnitude is a _____ | unit for measuring apparent brightness; how bright a star looks |
| Apparent magnitude depends on _____ and _____. | luminosity; distance |
| A smaller magnitude indicates a ____ star and a higher magnitude indicates a ____ star. | brighter; dimmer |
| Absolute magnitude refers to a star's _____. | true brightness/luminosity |
| Apparent magnitude depends on _____ and _____. | luminosity; distance |
| Star A has a magnitude of +7 while Star B has a magnitude of -2. Which star is brighter? Which star is dimmmer? | Star B; Star A |
| Absolute magnitude refers to a star's _____. | true brightness/luminosity |
| A star's spectral type is based on the appearance of ________ | Spectrum lines |
| What does Stefan-Boltzmann law tell us about stars and the main sequence? | It answers why not every star is on the main sequence, because of different radii |
| Star A has a magnitude of +7 while Star B has a magnitude of -2. Which star is brighter? Which star is dimmmer? | Star B; Star A |
| What spectral type is the Sun? | G2 |
| A star's spectral type is based on the appearance of ________ | Spectrum lines |
| Why does a star's spectral type indicate its color? | Because temperature sets a star's spectral type, and Wien's law |
| How does temperature affect a star's spectrum? | If too hot or cold, electrons are in wrong energy level to absorb light at a particular wavelength that corresponds to an element |
| What do binary star systems allow measurement of? | star masses |
| What is the order of star spectral types? | OBAFGKM |
| What does the HR diagram graph? (3 things) | Luminosity, temperature, and radius |
| What spectral type is the hottest? | O type stars |
| What does Stefan-Boltzmann law tell us about stars and the main sequence? | It answers why not every star is on the main sequence, because of different radii |
| What spectral type is the coolest? | M stars |
| White dwarfs are hot but dim. Why? | Because of their small radii/surface area |
| What spectral type is the Sun? | G2 |
| Where do the majority (90%)of stars lie on the HR diagram? | Main sequence |
| Why does a star's spectral type indicate its color? | Because temperature sets a star's spectral type, and Wien's law |
| Red giants are cool but very luminous. Why? | Because of their larger radii/surface area |
| What do binary star systems allow measurement of? | star masses |
| Red giants have _____ more energy than main sequence stars because of their ________. | 1000 times; larger surface area |
| What does Stefan-Boltzmann law tell us about stars and the main sequence? | It answers why not every star is on the main sequence, because of different radii |
| What does the HR diagram graph? (3 things) | Luminosity, temperature, and radius |
| White dwarfs are hot but dim. Why? | Because of their small radii/surface area |
| What does Stefan-Boltzmann law tell us about stars and the main sequence? | It answers why not every star is on the main sequence, because of different radii |
| Where do the majority (90%)of stars lie on the HR diagram? | Main sequence |
| White dwarfs are hot but dim. Why? | Because of their small radii/surface area |
| Red giants are cool but very luminous. Why? | Because of their larger radii/surface area |
| Where do the majority (90%)of stars lie on the HR diagram? | Main sequence |
| Red giants have _____ more energy than main sequence stars because of their ________. | 1000 times; larger surface area |
| Red giants are cool but very luminous. Why? | Because of their larger radii/surface area |
| For main sequence stars, luminosity, temperature, radius and mass _____ while lifetime _____. | increase; decrease |
| Red giants have _____ more energy than main sequence stars because of their ________. | 1000 times; larger surface area |
| What four factors influence the lifetime of a main sequence star? | Luminosity, temperature, radius, and mass |
| For main sequence stars, luminosity, temperature, radius and mass _____ while lifetime _____. | increase; decrease |
| Nuclear fusion replenishes lost _____ and creates _____ to counterbalance _____ . | energy; pressure; gravity |
| What four factors influence the lifetime of a main sequence star? | Luminosity, temperature, radius, and mass |
| Why do high-mass stars require more pressure | |
| Nuclear fusion replenishes lost _____ and creates _____ to counterbalance _____ . | energy; pressure; gravity |
| Why do high-mass stars require more pressure than low-mass stars? | To support a greater mass and consequently greater inward force of gravity to keep from collapsing |
| What is the reason for the formation of a protostar? | Collapsing gas clump rotates to become a disk |
| When does a protostar become a main sequence star? | When it starts fusing hydrogen to helium |
| Heat from a protostar collapsing radiates out as a(n) _____. | Emission nebula |
| Emission nebulae are also called _____ because they are composed of ionized hydrogen. | HII Regions |
| Protostars are difficult to observe because _____. (4 reasons) | Protostar stage very short; are surrounded by gas and dust, radiate mainly in IR; are so far away that light hasn't reached us yet |
| The average star spends _____ of its lifetime on the main sequence. | 90% |
| ______ is the thermonuclear fusion of hydrogen to form helium operating in the cores of massive stars on the main sequence. | CNO cycle |
| _____ occurs when most of the material collapsing to form a protostar has fallen into a disk around the star and a strong wind from the warm protostar ejects material from its poles. | Bipolar outflow |
| The creation of _______ requires that a young hot star (25,000 K) be relatively nearby. | emission nebulae |
| The HR diagram of a young star cluster shows | that low mass stars have not yet reached the main sequence yet. |
| What is a main-sequence star's primary energy source? | nuclear fusion |
| What must occur for an object to be considered a main-sequence star? (two things) | hydrostatic equilibrium and nuclear fusion in core |
| Why do nuclear fusion reactions only take place in the interior of a star? | High enough temperature and density in core |
| Hydrostatic equilibrium refers to the balance between ____ and ______. | Weight/gravity; pressure |
| The pressure of a gas depends on the _______ and ______ of the gas. | Temperature; density |
| How is a star's main-sequence lifetime determined mathematically? | Divide the star's amount of fuel (mass) by the rate of fuel consumption (luminosity) |
| Immediately after leaving the MS and becoming a red giant, high-mass stars begin the _____. | helium burning/triple alpha process |
| Immediately after leaving the MS and becoming a red giant, low-mass stars experience a ______ and then ______. | helium flash; expand |
| Why does the gas in a planetary nebula glow? | UV radiation from star core heats and ionizes the gas |
| What keeps white dwarfs in hydrostatic equilibrium? | Degenerate pressure |
| Why does the addition of too much mass make a white dwarf collapse? | Because degenerate gas creating pressure against gravity is easily crushed |
| Why does a type II or core-collapse supernova occur? | Because iron does not release energy |
| What is left after a Type II supernova? | Neutron star |
| What is the size of a neutron star? | A small city |
| What is the Schwarzschild radius? | Radius at which an object of a particular mass becomes a black hole |
| What is the Schwarzchild radius of the Sun (1 solar mass? | 3 kilometers |
| How is a black hole's presence detected or felt? | By it's gravity, electric charge, and/or angular momentum amplifying its magnetic field |
| What is the event horizon? | Boundary of a black hole where the inward flow of space reaches the speed of light at the Schwarzschild radius |
| Why can't an object travel out of the event horizon at the Schwarzchild radius? | Because nothing can travel through space faster than the speed of light |
| Hubble's study of Cepheids in M31 led to _______ and ______. | Classification of galaxies and expansion of the Universe |
| What is Cygnus X-1? | Probably a black hole |
| What is a noticeable feature of a spiral galaxy? | 2 or more arms winding out from a central disk |
| What is a noticeable feature of a barred spiral? | Arms emerge from ends of an elongated central region |
| What is characteristic of a S0 galaxy? | Has a disk but no spiral arms |
| Spiral galaxies contain a mix of ____ and ____ stars. | Pop I and Pop II |
| Which type of galaxy is the largest? | Ellipticals |
| What is characteristic of an elliptical galaxy? | No disk or arms, stars distributed around center in all 3 dimensions |
| Ellipticals contain mostly ____ stars. | Pop II |
| Why are ellipticals so large? | repeated galactic cannibalism |
| What explains a lack of Pop I stars in an elliptical galaxy? | Repeated galactic cannibalism used up most of the gas |
| What is characteristic of irregular galaxies? | Stars and gas scattered in random patches |
| Why are Pop I stars common in an irregular galaxy? | Large amount of interstellar matter for new stars to form |
| The Hubble Tuning Fork subdivides ellipticals by how ____ they look and spirals by how large ____ are and how tightly would _____ are. | Flattened; bulges; spiral arms |
| What does the redshift of galaxy spectrums imply? | That galaxies are moving away from us |
| What does Hubble law state? | More distant galaxies recede faster than nearby ones |
| How massive is the suspected black hole in the center of the Milky Way? | 5 million solar masses |
| What prevents the Milky Way's collapsing? | Orbital motion of its contents |
| What is the Milky Way's age? | 13 billion years |
| The location of what stars are used to map MW's spiral arms? | O and B Pop I stars |
| Where are Pop I stars found in the Milky Way? | In the disk and concentrated in spiral arms |
| Where are Pop II stars found in the Milky Way? | In the halo and bulge |
| ____ stars have approx. circular orbit while ____ stars have a tilted plunging orbit. | Pop I; Pop II |
| What causes stars to move in their own orbits around MW's center? | Gravity |
| How is the mass of the Milky Way determined? | By using rotation curve speed of stars at a variety of distances |
| What causes the distribution of galaxies in the Universe? | Expansion of the Universe |
| What is the cosmological principle? | Universe looks the same to every observer, regardless of observer's location in the Universe |
| What conclusion is drawn from the recession and distribution of galaxies? | The age of the Universe is 14 billion years |
Created by:
509591073