A Search for Habitable Planets Transit Tracks Finding
A Search for Habitable Planets Transit Tracks: Finding Extrasolar Planets a science & math activity
“transit” A Search for Habitable Planets
“transit” A Search for Habitable Planets
“transit” A Search for Habitable Planets
What’s this? A Search for Habitable Planets
A Search for Habitable Planets A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and Earth, so that Venus blocks a small spot of the Sun’s disk. Since the Sun is over 100 times larger in diameter than Venus, the spot is very small indeed.
Account of Jeremiah Horrock’s observations of the transit of Venus A Search for Habitable Planets
A Search for Habitable Planets Imagine you have a light sensor aimed at the star. BRIGHTNESS What would the transit of a book like if you made a graph of light intensity vs time? 0 0 TIME
A Search for Habitable Planets BRIGHTNESS Like this? 0 0 TIME
A Search for Habitable Planets BRIGHTNESS What would the transit of a planet look like if you made a graph of light intensity vs time? 0 0 TIME
Perhaps like this? A Search for Habitable Planets Such graphs are called “light curves. ” BRIGHTNESS How would a planet’s size and orbit period affect the transit—light curve? 0 0 TIME
A Search for Habitable Planets The light curve can lead to finding the SIZE of the planet and its DISTANCE from the star. Why would those characteristics be important?
A Search for Habitable Planets
A Search for Habitable Planets Is there a relationship between the planet’s period (time for one orbit) and how its distance from the star?
Kepler’s 3 rd Law A Search for Habitable Planets
A Search for Habitable Planets
A 3 = p 2 A Search for Habitable Planets
A Search for Habitable Planets
A Search for Habitable Planets
A Search for Habitable Planets Kepler 4 -b
A Search for Habitable Planets
Planet’s Size: Deducing the Planet’s Radius from Transit Data A Search for Habitable Planets Ap/As = Z Converting to a percentage 100 ( Ap/As) = Z% 100 (π rp 2 / π rs 2) = Z% 100 ( rp 2 / rs 2) = Z% rp 2/ rs 2 = Z%/100 rp 2 = rs 2 (Z%/100) rp = rs/10 √ Z% area of a circle = π r 2 The Sun is about 100 times the radius of the Earth. rsun = 100 rearth Substituting: rp = 100 rearth/10 ( √ Z% ) rp = 10 rearth ( √ Z% )
A Search for Habitable Planets
A Search for Habitable Planets Planet Name Kepler 4 b HAT-P 7 b HAT-P 11 b Mystery c Tr. ES 2 -b Kepler 5 b Kepler 6 b Kepler 7 b Kepler 8 b Period Orbital Distance Brightness Drop √Z Radius = 10 √ Z
A Search for Habitable Planets
A Search for Habitable Planets ( By permission Sternwarte Kremsmünster) A guy who’s thought a lot about planets
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