Unformatted text preview: Astro 3: Study Guide for Midterm #2 Reading: Chapters 7, 8, 9, 10, 11, 12, 13 Topics: Terrestrial planets Jovian planets Extrasolar planets The Sun Measurements of the stars Stellar life cycles 1. Terrestrial Planets o What are the different layers of a terrestrial planet interior? o What does the size of the lithosphere determine? o What factors determine geological activity? o What are sources of internal heat in terrestrial planets? o How do the geological activity on the Earth and the Moon compare? o What about Venus vs. Mercury? o What does heat travel from the interior of a terrestrial planet to its surface? o Why are larger terrestrial planets hotter? o How are surface area and volume related for a sphere? o Which terrestrial planet has the strongest magnetic field? o What are the processes that shape terrestrial planet surfaces? o How can cratering be used to gauge the age of a terrestrial planet's surface? o How are volcanism and erosion related? o What is an atmosphere? o What impact does an atmosphere have on a terrestrial planet's surface temperature? o Which terrestrial planet has the thickest atmosphere (in terms of atmospheric pressure)? The thinnest atmosphere? o What is the composition of Earth's atmosphere? o What is the greenhouse effect? o What are greenhouse gases? 2. Jovian planets o What is the composition of Jupiter and Saturn? o What is the composition of Uranus and Neptune? o How do the densities of Jupiter and Saturn compare? o Why is Jupiter denser than Saturn? o Why are Uranus and Neptune denser than Saturn? o Why do Uranus and Neptune have a different composition from that of Jupiter and Saturn? o What are the interior structures of the Jovian planets? o Why do Uranus and Neptune have a bluish atmosphere? o What gives rise to the banded atmospheres on Jupiter and Saturn? o What is the origin of the large Jovian moons? o What evidence supports the picture of the large moon origin? o What is one exception to this scenario? o What is the origin of the small Jovian moons? o What evidence supports the picture of the small moon origin? o What are the Galilean moons and the important characteristics of each? o What is a tidal force? o What is special about Saturn's moon Titan? o What is special about Saturn's moon Enceladus? o Do Jovian moons show evidence for geological activity? o Which jovian planets have ring systems? o What is the thickness of Saturn's ring system? o What is the likely origin of Saturn's ring system? 3. Extrasolar Planets o What are the challenges associate with detecting extrasolar planets? o When was the first extrasolar planet discovered around a main-‐sequence star? o What are the key techniques we discussed for finding extrasolar planets? o Where is the center of mass in the Sun/Jupiter system (neglecting effects of other planets)? o How fast does the Sun move around the center of mass of the Sun/Jupiter system? o What about the Sun/Earth system? Where is the center of mass, and how fast does the Sun orbit around this center of mass? o Why does the orientation of the extrasolar planetary system matter for radial velocity measurements of extrasolar planets? o What would a multiple planet system look like in a plot of stellar radial velocity vs. time? o What type of planetary system is most easily detected with the radial velocity technique? o What are the types of planetary systems most easily discovered with direct imaging? Why look in the infrared? o Has the planetary transit phenomenon been observed in our own solar system? o Can we observe Jupiter transiting the Sun? o What are some of the highlights from the Kepler mission? o What is the "habitable zone"? o What does the overall distribution of planet masses look like? 4. The Sun o What are the layers of the solar interior? The solar atmosphere? o What are the net inputs and outputs of the proton-‐proton chain nuclear reaction? o What is the cause of solar activity? What are some of the key phenomena observed as solar activity? 5. Measurements of stars o How are luminosity and apparent brightness related? o Example: 2 stars, A and B, with the same luminosity. B has an apparent o brightness 16 times fainter than that of A. What do you conclude? o What is the relationship between stellar parallax and distance? o Example: A star has a measured parallax of 2 arcsec. What is its distance? (Note: no stars have measured parallaxes this large -‐-‐ this is an imaginary thought question). o Example: A star has a measured parallax of 0.01 arcsec. What is its distance? o Example: What is the parallax of a star at d=10 pc? o What two key properties does a star's luminosity depend on? o Which law of thermal radiation is contained in the expression for a star's luminosity? o Example: The Sun will turn into a red giant with RRG=300 Rsun and surface temperature TRG=3100 K. How will the luminosity of the Red Giant compare with that of the current Sun? o What are the different spectral types? o On the main sequence the spectral types not only indicate a sequence of temperature, but also a sequence of....? o What is the H-‐R diagram? o Where is the Main Sequence on the H-‐R diagram? o What is the defining characteristic of stars on the Main Sequence? o Where are white dwarfs in the H-‐R diagram? o Where are Red Giants in the H-‐R diagram? o Example: Let's consider 4 types of stars, O, F, G, M. o Which has the hottest surface temperature? o Which has the same spectral type as the Sun? o Which has the longest Main Sequence lifetime? o Which has the smallest mass? o How do we estimate Main Sequence lifetime? o Which stars have the shortest main sequence lifetimes? o How do we measure the masses of stars? o How do star clusters work as clocks? 6. Stellar life cycles o What happens when a star leaves the main sequence? o What is a giant star? o What is the helium flash? o What do stars do on the horizontal branch, and how long do they spend there? o How many times will the Sun be a red giant? o How do low-‐mass stars end their life? o What is a planetary nebula? o What happens in the evolution of a high mass star? o What type of hydrogen fusion occurs in high mass stars? o What happens when a high mass star leaves the main sequence? o What happens as a high-‐mass star uses up the available fuel? o Why does nuclear fusion in high-‐mass stars stop at iron? o What happens when a high-‐mass star explodes? ...
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- Fall '07