ExoplanetsAstr 101, Fall 2014

Exoplanets : outline

1) Why should we look for them2) Types of exoplanets discovered3) Detection methods4) Planetary atmospheres5) Habitable zones6) Future

Understanding formation of planets

- can we predict that SS should be the way it is from first principles and knowledge of all boundary conditions?

Why look for exoplanets?

To answer questions:- Are planets common or rare? - How do they form ? - How do they depend on location in the Galaxy, etc.

Exoplanets : outline

1) Why should we look for them2) Types of exoplanets discovered3) Detection methods4) Planetary atmospheres5) Habitable zones6) Future

Diversity of Exoplanets

SizeDistance from a star

Multi-planet systems

Number of planets (here Kepler 11-b)

Exoplanets : outline

1) Why should we look for them2) Types of exoplanets discovered3) Detection methods4) Planetary atmospheres5) Habitable zones6) Future

Direct imaging

Direct imaging

HR 8799

Gravitational Microlensing

- planet bends light from distant stars, and makes them appear brighter

Transits

Transits: limitations

- easier to detect bigger planets - why?- require particular alignment of the planetary orbital plane and our line of sight

Radial velocity

Detect the wobble of the star, as they both orbit the common center of mass

Radial velocity

Radial Velocity

* simulator: http://astro.unl.edu/naap/esp/animations/radialVelocitySimulator.html

Exoplanets : outline

1) Why should we look for them2) Types of exoplanets discovered3) Detection methods4) Planetary atmospheres5) Habitable zones6) Future

Transmission spectroscopy

Light contains many wavelengths , with useful information

Atmospheric properties

Questions to answer:

- what molecules are there ?- temperature profile ?- the structure of the atmosphere (clouds, hazes)

Problems with spectra

- Lots of noise - models are degenerate

GJ 1214b models: H dominated H with clouds Water dominated

Exoplanets : outline

1) Why should we look for them2) Types of exoplanets discovered3) Detection methods4) Planetary atmospheres5) Habitable zones6) Future

Habitable Zone

Could we live there?

Exoplanets : outline

1) Why should we look for them2) Types of exoplanets discovered3) Detection methods4) Planetary atmospheres5) Habitable zones6) Future

Future

Thirty Meter Telescope Giant Magellan Telescope

- more resolution- more planets- more science!

Questions?