Upload
ross-parsons
View
214
Download
1
Embed Size (px)
DESCRIPTION
A New Field of Exploration Other Galaxies – 1920s Wikimedia Commons Quasars and Black Holes – 1960s-1970s Cosmic Microwave Background – 1970s-1990s
Citation preview
Exoplanet Discovery
Joshua PepperVanderbilt University
Keivan Stassun, Rob Siverd, Leslie Hebb, Phil Cargile - Vanderbilt UniversityRudi Kuhn – The University of Cape Town
Scott Gaudi, Thomas Beatty – The Ohio State University
Summary
• 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.fas.org/irp/imint/docs/rst/Sect20/A6.html
Cosmic Microwave Background – 1970s-1990s
http://www.space.com/bestimg/?guid=4499b3474b769&cat=strangest
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
1700 1800 1900 2000
5
10
8 + 729
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
• Direct Imaging
• Radial-Velocity
• Transits
Background star (source)
Foreground star with planet (lens)
From Beaulieu, et al. 2006, Nature, 439, 437
Shift due to terrestrial planet is one microarcsecond1,000,000 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)
Discovery Methods• Microlensing
• Astrometry
• Direct Imaging
• Radial-Velocity
• Transits
Seeing the Earth around the Sun:
10,000,000,000 to 1
Radial Velocity motion of the sun due to the Earth is
10 cm per second, 0.22 mph.
Discovery Methods• Microlensing
• Astrometry
• Direct Imaging
• Radial-Velocity
• TransitsFrom Bouchy, et al., 2005, A&A, 444, L15
Transits
planet diameter
brig
htne
ss
time
~1%
Finding Transits
1. Monitor all stars and derive lightcurves2. Search for transit like behavior (computing-
intensive!)3. Do follow-up observations to eliminate false
positives4. Confirm planets with full dynamical information
• Hot Jupiters• Eccentric and inclined orbits • New Planet types
• 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 Highlightsplanet scattering is common
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-SouthDeployed 2009 to Sutherland, South Africa
Operated by Vanderbilt, Fisk University, and the University of Cape Town
KELT-NorthDeployed 2005 to Winer Observatory, AZ
Operated by Ohio State and Vanderbilt
Fields Observed by KELT
Blue line – Galactic plane 42% of the skyGreen line – ecliptic
5 years of data
1.5 years of data
Discovery Space for KELTBright (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 = 7.67Rp = 1.18 RJ
P = 2.22 days
A transit survey and…comets?
Comet Schwassmann-Wachmann-1
A transit survey and…comets?
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