The sky
What is an AU?
The average distance from the earth to the sun
A continuous spectrum shows what?
Emission at all wavelengths
It is when gravity and radiation pressure are balanced inside a star.
What is the end state of a G star?
White dwarf
Spacetime tells matter how to move
What are right ascension and declination?
Parallels to longitude and latitude on the celestial sphere.
What does a spectrograph do to light?
Split it into wavelengths like a rainbow.
What is a protoplanetary disk?
It is the disk of gas and dust that collects around a protostar and it provides the material from which a planet forms.
What causes a red giant to puff up?
The heat from the hydrogen shell burning.
Describe 3 ways we measure the distance to other galaxies. When are each of these ways applicable?
Cepheids, type Ia supernova, and the Tully-fisher relationship. Know when each of these methods apply. Cepheids are applicable when we can resolve individual stars within the galaxy. Type Ia supernova can be observed at great distances and don't need to be individually resolved because they are so bright. Tully-Fisher relates rotational speed to luminosity making it only applicable for spiral galaxies.
What are Kepler's 3 laws?
All orbits are elliptical.
Orbits sweep out equal area in equal time.
Period squared is proportional to semi-major axis cubed.
Higher temperatures mean what for the wavelength, frequency, and energy of light?
Wavelength is shorter, frequency higher, and energy higher.
What are the three types of energy transport and which ones are the dominant modes in the sun?
Radiation, convection, conduction. Radiation and convection are the dominant modes of energy transport in the sun.
What is true about the surface temperature, luminosity, and color of a red giant compared its main sequence counterpart? Why?
Cooler, brighter, and redder. Cooler because it has expanded. Brighter because more square meters on the surface to radiate light. Redder because it is cooler.
What is the observational evidence that the expansion of the universe is accelerating?
The distances measured via type Ia supernova are farther than those measured from redshift (which assumes a constant expansion rate).
What is retrograde motion?
The apparent backwards motion of celestial objects on the sky due to the differing orbital speeds of earth and the other bodies.
What happens when an electron in an atom goes from a higher energy level to a lower one?
It emits a photon of exactly the energy difference between the two levels.
What is plotted on an H-R diagram?
Luminosity vs temperature.
What is the lowest possible mass of a main sequence star that will end its life in a supernova?
8 solar masses
Why is the CMB evidence for the Big Bang?
What is the distance that light travels in 2 minutes?
3.6e10 m
What is the Doppler effect?
It is when a wave is shifted to a longer wavelength when it is coming from a source moving away from the observer. The reverse is true if the source is moving towards the observer.
What is the primary cause of the differences that we observe in main sequence stellar spectra?
Temperature
What is the difference between a type Ia and a type II supernova? How are they both different from a nova?
Type II is caused by the collapse of a stellar core to a neutron star. Type Ia is caused by a white dwarf suddenly going over the Chandrasekhar limit. A nova is caused by a white dwarf slowly going over the Chandrasekhar limit and just blowing off the outer layers to get back under the limit.
Why is an accreting supermassive black hole the best explanation for the "engine" behind quasars?
Quasars are both incredibly energetic and physically compact. A black hole is the only object that is massive enough to speed up material fast enough that friction and loss of gravitational potential energy are large enough to explain the energy output. Black holes are also incredibly compact.