Lecture 16: Searching for Habitable Planets: Remote Sensing Methods and parameters we can measure Mean density measurements: internal structure Measurements of surface temperature Atmospheric composition and temperatures Mapping of the surface
Star-to-planet inequalities: In light: (optical) to 10 7 (infrared) In mass: 10 5 to 10 3 In size: 10 2 to 10.
HD b: a Hot Jupiter
Methods: Mass Determination Newton’s law of universal gravitation & equality of forces: M s a s = M p a p (center of mass)
Mass: Radial velocities seen in star HD the variation is due to a planet that is less massive than Jupiter. (Mazeh et al. 1999; Marcy et al. 2000)
More on Orbits: Angular Momentum Conservation of Angular Momentum
Mass: For HD b: M p sin(i) = M s v s P / 2 a p = const. x ( M s / 1.1M Sun ) M jup Transit light curve helps derive the orbit inclination: i = 86 o Both M p and R p determined to better than 5%!
What can we learn from transiting extrasolar planets HD b: Dimming of light due to transit, observed with HST. Brown, Charbonneau, Gilliland, Noyes, Burrows (2001) Tells us DIRECTLY: Planet radius, INDIRECTLY: Planet density Planet composition
Mass-Radius Diagram: Hot Jupiters Super-Earths
Rocky & Water Planets Credit: S. Cundiff
Mass (Earth mass) Radius (Earth radius) Transiting Planets on the Mass-Radius Diagram Earth Kepler-10b CoRoT-7b GJ1214b Earth composition 50% H 2 O 20% H/He Uranus Neptune Kepler-4b HAT-P-11b GJ436b
Mass [M Earth ] Radius [R Earth ] E V M Kepler-10b Earth and Super-Earth Mass–Radius Domain Batalha et al (2011) Zeng & Sasselov (2011) % H/He GJ1214b CoRoT-7b Kepler-11b Kepler-11f
Model: Seager & Sasselov 2000 Detection: Charbonneau et al 2002
HD b: a Hot Jupiter
Atmosphere: What is special about atomic Na and the alkali metals? Seager & Sasselov (2000)
Atmosphere: Theoretical Transmission Spectra of HD b Wavelength (nm) Occulted Area (%) Seager & Sasselov (2000)
Atmosphere: The tricks of transmission spectroscopy: Brown (2001)
A star and its planet in infrared light (Artist conception)
Direct Detection of Thermal Emission Infrared Eclipses of Hot Jupiters: Spitzer Space Telescope
First detection of light from planets orbiting other stars D. Charbonneau, & D. Deming et al. March 2005
Infrared Eclipses
Infrared Eclipses in HD : Measuring the Emitted Heat Time (in fraction of day) Orbital phase Relative Intensity or Brightness Eclipse detection (Feb. 20, 2006) by Deming et al. using the Spitzer Space Telescope - in infrared light (heat)
Spectra Observed IR data points vs. models Knutson, Charbonneau, et al. (2007)
A study of an extrasolar planet Heather Knutson & Dave Charbonneau (2007)
A map of an extrasolar planet Heather Knutson & Dave Charbonneau (2007)
Main points to take home: 1) Methods and parameters we can measure 2) Mean density measurements: internal structure 3) Measurements of surface temperature 4) Atmospheric composition and temperatures 5) Mapping of the surface