Planetary transits
Sherwood observatory
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First transiting exoplanet: HD209458b
Henry et al. 2000, ApJ 529, L41
Charbonneau et al. 2000, ApJ 529, L45
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HD209458b with HST
Brown et al. 2001, ApJ 529, L41
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Wide Angle Search for Planets (WASP)
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28,590,964 stars
196,830,798,116 measurements
WASP-1b: Garafia-1
WASP-1 = F7V
Collier Cameron…Wheatley 2007
WASP-2 = K1V
Charbonneau et al. 2007
R = 1.44 ± 0.04 RJup
K1 = 114 ± 13 ms-1
Mp = (0.80 – 0.98) ± 0.11 MJ
R = 1.04 ± 0.05
RJup
K1 = 155 ± 7 ms-1
Mp = (0.81 – 0.95) ± 0.04 MJ
Mass-radius
relation
Jupiter
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Pont et al. 2005
Charbonneau et al 2007, ApJ 658, 1327
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Radius evolution of a Jupiter mass planet
Baraffe et al 2009
} Irradiated by Sun at 0.045 AU
- No core, no irradiation
- 20 ME core, no irradiation
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require
additional
thermal energy
consistent with
irradiation and
no core
proves some
exoplanets
have cores of
heavy elements
Charbonneau et al 2007
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Interior heating mechanisms
• Tidal heating
– But most hot Jupiters have circular orbits
• Kinetic heating
Guillot & Showman 2002
• Ohmic Heating
Batygin & Stevenson 2010
Laughlin et al 2011
Transits from space
CoRoT
Leger et al. 2009
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Transits from space: CoRoT-7b
Leger et al. 2009
Queloz et al 2009
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Mass-radius relation for
transiting exoplanets
WASP (>30%)
Kepler
Solar System
Kepler
2009
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About 10 small candidates in
the habitable zone
Planet occurrence rates from Kepler
Howard et al 2012
Super-Earths
Neptunes
Jupiters
YouTube
Kepler multiple transiting systems: Kepler-11b,c,d,e,f,g
Circumbinary planets
Kepler-16b aka Tatooine
Kepler habitable zone candidates
However, need brighter examples for radial velocity confirmation,
density measurement and atmospheric characterisation
NGTS: Next Generation Transit Survey
UK led: Warwick, Leicester, Cambridge & Belfast
With Geneva Observatory and the German Space Agency (DLR)
Image: Richard West
NGTS under construction at Paranal Observatory, Chile
VLT
VISTA
NGTS
Future space missions for small planet discovery
PLATO, ESA ?
TESS, NASA
Rossiter-McLaughlin effect
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Radial Velocity of 51 Peg b
Mayor & Queloz 1995, Nature 378, 23
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Rossiter-McLaughlin effect
in HD 209458
4 deg misalignment
Supports migration by ang mom
transfer in accretion disc
Winn et al 2005
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Retrograde orbits
• 34 systems well aligned
• 19 systems strongly misaligned
of which 8 retrograde
WASP-17b: Triaud et al 2010
HAT-P-7b: Winn et al 2009
Secondary
eclipses
Spitzer Space Telescope
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HD 209458 at
24 microns
Deming et al
2005
Nature 434, 740
Eclipse depth
0.26%
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HD209458b at a range
of wavelengths
Knutson et al. 2008
ApJ 673, 526
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CO
H20
H20
Knutson et al. 2008, ApJ 673, 526
Temperature inversion in HD209458b
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Burrows, Sudarsky & Hubeny 2006
Temperature inversion due to TiO opacity?
4.5 microns
8 microns
with Tio/VO
without
TiO/VO
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HD189733b
around half
an orbit
Knutson et al.
2007, Nature
447, 183
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Planetary atmospheres: secondary eclipses
Madhusudan et al 2010, Nature
Methane and carbon
monoxide in WASP-12b?
HST optical secondary eclipse of HD189733b: the “blue planet”
Evans et al, 2013
Transmission spectroscopy
Brown 2001
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Detection of sodium
in the atmosphere of
HD209458b
Charbonneau et al. 2002
ApJ 568, 377
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Detection of
sodium in the
atmosphere of
HD209458b
Charbonneau et al. 2002
ApJ 568, 377
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Transmission spectroscopy
HD189733b
Sing et al 2011
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Planetary atmospheres:
transmission spectroscopy
Dust and clouds in HD189633b
Pont et al 2013
Evaporation of
HD209458b
Vidal-Madjar et al 2003, Nature 422, 143
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The Sun in X-rays
Lx < 10-3 LBol
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Keith Horne