Download Goal: To understand how Saturn formed and what its core

Goal: To learn about the Kepler
Mission and the Transit Method
Objectives:
1) To learn about the basics of the spacecraft
2) To understand Mission goal
3) To learn the reasoning about some of its
quirks
4) To explore what we have found so far from
Kepler
5) To understand the transit/eclipse method
Launched
• 2009 March 6, 10:49 pm EST.
• https://www.youtube.com/watch?v=A1pKR
oUk-A4
NGC
6791
• Since in
space can
measure
brightness
very
accurately
Field of View
• 100,000 stars
for Kepler to
constantly
monitor for 3.5
years
Actual
images
• Black
= star
Quirks
• Spacecraft slowly trails earth in orbit
• Spacecraft “rolls” every 3 months
• Looks at a large
field of view (about
15 degrees) all at
once
Transit
• When a planet passes in front of a star it
partially eclipses the star.
• A solar eclipse for example occurs when
the moon blocks the sun
• Since planets are
small they only
block a small
portion of the star
We can tell:
• Just like before with the wobble method
we can determine:
– Orbital period
– Orbital distance
– Mass
Difficulties
•
•
•
•
Sunspots can again pose a problem
Binary stars
Stellar Flares
Other random activity
• Planet has to have orbital plane that makes it
pass in front of the star (very limiting)
• First one detected Nov, 1999 (discovered using
wobble). 2nd was 2002 (first discovered using
transit - OGLE-TR-56 b)
Initial findings
Much more accurate!
Candidate vs confirmed
• Since NASA wants to see 3 transits per
planet.
• Found hot Jupiters in months.
• Objects in Mercury orbits in about a year
• Planets in Earth like orbits in 3 years.
Expectations:
• 100,000 stars
• If 10% have planets then 10,000 star
systems
• However, since Kepler uses transits to find
planets only 0.5% of the systems will be
detectable.
• That gives 500 expected systems to
observe.
Actual:
• Candidate exoplanets: 4,706
• Confirmed exoplanets: 1,039
• Confirmed exoplanets less than twice
Earth-size in the habitable zone: 12
• So this implies that the % of stars with
planets is somewhere between 20% and
80%
What Kepler will not be able to do
• Observe the atmosphere.
• We are still finding the planets indirectly.
• The parent stars are too far away and too
dim to do detailed analysis from the
ground.
• Kepler does not take spectrums…
Conclusion
• We have learned about how to use
gravitational lensing as a tool.
• We have examined the complications with
this style of observation.