Transcript Exoplanet_talk_at_Vanderbilt_for_HEP

Exoplanet Discovery
Joshua Pepper
Vanderbilt University
Keivan Stassun, Rob Siverd, Leslie Hebb, Phil Cargile - Vanderbilt University
Rudi Kuhn – The University of Cape Town
Scott Gaudi, Thomas Beatty – The Ohio State University
Summary
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Historical background
How do we find exoplanets?
Current state of discovery
The KELT project
A New Field of Exploration
Other Galaxies
– 1920s
Wikimedia Commons
Quasars and
Black Holes –
1960s-1970s
http://www.space.com/bestimg/?guid=4499b3474b769&cat=strangest
http://www.fas.org/irp/imint/docs/rst/Sect20/A6.html
Cosmic Microwave
Background –
1970s-1990s
How did we get here?
Most of modern history
9…(or 8) planets
Now… 8 + 729 planets
The Olden Days (pre-1992)
All the planets in the Universe…
Known since ancient times
1781
1846
1930
Explosion of Discovery
8 + 729
10
5
1700
1800
1900
2000
A New Field of Exploration
Dust grains → Brown Dwarfs
Sizes: 10-7 m → 107 m
Masses: few thousand atoms → 0.08MSun
Discovery Methods
• Microlensing
• Astrometry
Background star (source)
Foreground star with planet (lens)
• Direct Imaging
• Radial-Velocity
• Transits
From Beaulieu, et al. 2006, Nature, 439, 437
Discovery Methods
• Microlensing
• Astrometry
• Direct Imaging
• Radial-Velocity
• Transits
Shift due to terrestrial planet is one microarcsecond
1,000,000 times smaller than the size of the star itself
Discovery Methods
• Microlensing
• Astrometry
• Direct Imaging
• Radial-Velocity
• Transits
NASA, ESA, P. Kalas, J. Graham, E. Chiang, E. Kite (University of California,
Berkeley), M. Clampin (NASA Goddard Space Flight Center), M. Fitzgerald
(Lawrence Livermore National Laboratory), and K. Stapelfeldt and J. Krist (NASA
Jet Propulsion Laboratory)
Seeing the Earth around the Sun:
10,000,000,000 to 1
Discovery Methods
• Microlensing
• Astrometry
• Direct Imaging
• Radial-Velocity
• Transits
From Bouchy, et al., 2005, A&A, 444, L15
Radial Velocity motion of the sun due to the Earth is
10 cm per second, 0.22 mph.
Transits
brightness
~1%
planet diameter
time
Finding Transits
1. Monitor all stars and derive lightcurves
2. Search for transit like behavior (computingintensive!)
3. Do follow-up observations to eliminate false
positives
4. Confirm planets with full dynamical information
Discovery Highlights
• Hot Jupiters
• Eccentric and inclined orbits
• New Planet types
planet scattering is
common
• Puffy giants / Dense giants
• Ice and ocean worlds
• Super-Earths – metal/gas or water?
• Exciting systems
– Binary planets
– Free floating
– Planets in habitable zone, >100 from Kepler
already
Discovery Highlights
• Planet Demographics from
Kepler (only for Period < 50
days!)
– Metallicity trend holds for gas
giants but not Neptunes or
terrestrial planets
– Neptunes and Super-Earths are
common, 30% to 50% of sunlike
stars have them
– Planets come in packs
– Frequency is inversely
proportional to stellar mass
Directions for Future Discovery
• 729 planets discovered (and confirmed)
• Two directions for future discovery
– Rare, extreme, or valuable
– General demographics
Verify theories of formation
& evolution
KELT: The Kilodegree Extremely
Little Telescope
• 2 Fully Robotic
telescopes
• 4k x 4k CCD,
9 micron pixels
• 4.5 cm aperture
• 26 x 26 degree
field of view
• $60,000 per
telescope
KELT: The Kilodegree Extremely
Little Telescope
KELT-North
KELT-South
Deployed 2005 to Winer Observatory, AZ
Deployed 2009 to Sutherland, South Africa
Operated by Ohio State and Vanderbilt
Operated by Vanderbilt, Fisk University, and the
University of Cape Town
Fields Observed by KELT
5 years
of data
1.5
years
of data
Blue line – Galactic plane
Green line – ecliptic
42% of the sky
Discovery Space for KELT
Bright (8 < V < 11) stars with transiting planets
Opportunity for followup investigations
– Break msin(i) degeneracy, get mass and inclination
– Planet Radius  density  composition / core mass
– Atmosphere
• Transmission spectroscopy
• Emission spectroscopy
– Spin-orbit alignment (Rossiter-McLaughlin effect)
– Moons & Rings
How large is 26 degrees, really?
23” x 23” pixels
26 degrees
Blind Recovery of Known Planets
HD189733b
V = 7.67
Rp = 1.18 RJ
P = 2.22 days
A transit survey and…comets?
A transit survey and…comets?
Comet Schwassmann-Wachmann-1
KELT Research Program
• Primary Science
– Bright transiting planets
• Secondary Science
– Variable stars, especially eclipsing binaries
– Solar system science
– Combination with other transit surveys
KELT-South Telescope