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23 Cards in this Set
- Front
- Back
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What is the 1 x 10 x 10 rule? |
1 Sun diameter = 10 Jupiter's = (1 Jupiter = 10 Earth diameters) |
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What is the 1 x 5 x 50 rule? |
Earth is 1 AU from the Sun, Jupiter is 5 AU from the Sun, Kuiper Belt is 50 AU from the Sun |
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If the Earth is the size of a baseball (8cm), the moon is the size of a toonie, how far apart do their relative sizes need to be? |
30 cm |
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Do we expect there to be other solar systems around other stars in our galaxy? |
Yes
Copernicus introduced Sun center (heliocentric) notion, rather than geocentric (earth centered)
* at least 70% of all stars harbour at least 1 planet |
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What is some observational evidence that the Solar Nebula Hypothesis is true? |
1) Difference b/w inner rocky and outer gaseous planets
2) Planets are concentrated on the ecliptic plane |
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What can we measure for a star? |
1) Spectra (most important)
2) Brightness/Colour
3) Position on sky (direction) |
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What is direct detection? Why not use this? |
Take a picture.
1) Seeing -Difficult to get a good picture (image appears as a disk with light spread out around it
2) Contrast - Dependent on how bright the star is (how big/hot it is)
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What is indirect detection? What are the three methods of indirect detection? |
-Focus on the parent star, not the planet
1) Astrometric Motion (not successful) 2) Doppler Wobble 3) Transit Eclipse (most successful)
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What is the concept of Astrometric Motion? |
Sun exerts a force on the planets, planets exert same force on the Sun. (Sun is so much more massive than the planets so it doesn't appear to move --> planets orbit though b/c of Sun)
- Measure direction to the Sun, and wobble of Sun do directly get a planets orbit
* Doesn't work though b/c everything is too far |
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What is the concept of the Doppler Wobble? |
Using the spectrum of the sun to see the doppler effect: -Blue Shift = TOWARDS (high frequency/pitch) -Red Shift = AWAY (low frequency/pitch)
Gives you: -Velocity at which the object is traveling towards/away from you -Orbital period (therefore size of orbit)
Limitation -Works if shifts are BIG (big planets very close to stars) --> therefore all the first extrasolar planets discovered were hot Jupiters |
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What was the first planetary object found by Doppler Wobble? |
51 Pegasi |
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What is the indirect detection concept of Transit Eclipses? |
-When an object passes across the face of another object (hope for eclipses) -Measured b/c it is a periodic phenomena -Method found most planets to date -Best for observing planets in our plane (where we can see the stars edge on) |
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What does the "light curve" for a transit eclipse tell us? |
-Orbital period -Therefore size of the planet (Kepler's 3rd) relative to the star (but not mass) --> Smaller planet = steeper drop --> Bigger planet = less steep drop -Relative brightness (less when object in front of star) -composition of planets atmosphere by spectra of transit |
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Which methods of indirect detection give us orbital period? |
Transit, Doppler, Astrometric |
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Which methods of indirect detection give us orbital distance? |
Doppler, Astrometric, Transit (measured using Kepler's 3rd Law from orbital period) |
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Which methods of indirect detection give us mass? |
Doppler, astrometric (based on amount of stellar motion caused by planet's gravitational tug) |
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Which methods of indirect detection gives us the planet's size (radius)? |
Transit (measured by the light curve dips caused by transit) |
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Which methods of indirect detection gives us density of the planet? |
Transit (size/volume) + Doppler (mass)
* Density of gas giants similar to water * Super Earths denser than our Earth |
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Which methods of indirect detection gives us atmospheric composition, temperature |
Transit, or direct detection |
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What is the challenge of Hot Jupiters? |
Composed similar to Juipter, but were found in rocky area of solar system formation |
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What is naive falsification? |
The incorrect belief that simply finding a new theory that goes against a dominant existing one, disproves the original dominant theory
-Assumptions can be changed, theories can be improved --> (Uranus perturbed orbit led to finding Neptune) |
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Why is our Jupiter not a Hot Jupiter? |
Planetary migration? --> Hot Jupiters formed in the outer Nebula and moved to the area closer to the Sun? --> mass of Jupiter was too big to move proplanetary disk
-Migration stops when disk is gone (maybe Jupiter's disk dissipated very quickly - could not be tugged on by Sun's gravity) |
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What is the Anthropic argument as to why our Jupiter is not a Hot Jupiter? |
If Jupiter was a hot jupiter, we wouldn't be here...it would have had to cross the orbits of the inner planets (inner planets wouldn't have formed including Earth) |
