iau symposium 276 -- torino, 12 october 2010 statistical patterns in ground-based transit surveys...

IAU Symposium 276 -- Torino, 12 October 2010

Statistical patterns in ground-based Statistical patterns in ground-based transit surveystransit surveys

• Andrew Collier CameronAndrew Collier Cameron

• University of St AndrewsUniversity of St Andrews

SuperWASPWide Angle Search for Planets

TrES: The Trans-atlantic Exoplanet Survey


Ground-based transit surveysGround-based transit surveys

STARE PSST SLEUTH

HAT

XO

HAT-S WASP


Geographical distributionGeographical distribution

WASP-N(8)

WASP-S(8)

HAT-S(4)

STARE(1)

SLEUTH(1) PSST(1)

HAT(2)XO(2)HAT(4)

HAT-S(4)HAT-S(4)

HAT(1)

IAU Symposium 276 -- Torino, 12 October 2010• Typically ~ 5000 obs spanning 120N per seasonTypically ~ 5000 obs spanning 120N per season

WASP observations per starWASP observations per star


Bright (V<14) Transiting planetsBright (V<14) Transiting planets


Red noise and detection thresholdRed noise and detection threshold

Smith, A M S et al, 2006

80 nights

130 nights

80 nights

130 nights


Orbital period distributionOrbital period distribution

Orbital period in days

Cum

ulat

ive

frac

tion


Host-star apparent magnitudesHost-star apparent magnitudes

V magnitude

Cum

ulat

ive

frac

tion


Host-star effective temperaturesHost-star effective temperatures

• Bentley 2009, PhD thesis, Univ.of KeeleBentley 2009, PhD thesis, Univ.of Keele

All dwarfs in WASP archive


Smaller stars yield smaller planetsSmaller stars yield smaller planets


Super-Jupiters & BDsSuper-Jupiters & BDs

With thanks to Magali Deleuil


It isn’t a planet until you’ve weighed itIt isn’t a planet until you’ve weighed it• Magnitude range matches capabilities of RV Magnitude range matches capabilities of RV

spectrometers on 2-10m telescopes:spectrometers on 2-10m telescopes:– OGLE: VLT8.2m/UVESOGLE: VLT8.2m/UVES

– TrES: Keck10m/HIRESTrES: Keck10m/HIRES

– HAT: OHP1.93/SOPHIE; SUBARU8.4/HDSHAT: OHP1.93/SOPHIE; SUBARU8.4/HDS

– XO: McDonald2.7, HET11.0XO: McDonald2.7, HET11.0

– WASP-N: OHP1.93/SOPHIE, NOT2.4/FIESWASP-N: OHP1.93/SOPHIE, NOT2.4/FIES

– WASP-S: Swiss Euler 1.2m, ESO3.6/HARPSWASP-S: Swiss Euler 1.2m, ESO3.6/HARPS


Planetary mass-radius relationPlanetary mass-radius relation


Host-star MetallicitiesHost-star Metallicities

[Fe/H]

Fre

quen

cy


Fressin et al (2007)Fressin et al (2007)


Gas-giant mass-radius relationGas-giant mass-radius relation


Separation - Mass relationSeparation - Mass relation• Mazeh, Zucker & Pont Mazeh, Zucker & Pont

(2005)(2005)

• Low-mass gas giants Low-mass gas giants avoid small separations.avoid small separations.

• Ice-giants and super-Ice-giants and super-Earths behave Earths behave differently. differently.

• Symbol size denotes Symbol size denotes planet radius.planet radius.


Irradiation - Mass relationIrradiation - Mass relation• Low-mass gas giants Low-mass gas giants

avoid strong avoid strong irradiation.irradiation.

• Inflated planets found Inflated planets found close to boundary.close to boundary.

– Symbol size denotes Symbol size denotes planet radius.planet radius.

• Cf. Baraffe et al 2004Cf. Baraffe et al 2004– Evaporation/expansionEvaporation/expansion

– Critical mass at radius aCritical mass at radius a


Irradiation-radius relationIrradiation-radius relation• Guillot & Showman Guillot & Showman

20022002

• Fressin et al 2007Fressin et al 2007

• Symbol size denotes Symbol size denotes planet mass range:planet mass range:

– Low: 0.0 to 0.5 MLow: 0.0 to 0.5 MJJ

– Mid: 0.5 to 2.0 MMid: 0.5 to 2.0 MJJ

– High: Above 2.0 MHigh: Above 2.0 MJJ


Irradiation-radius relationIrradiation-radius relation• Most apparent in Most apparent in

restricted mass restricted mass ranges.ranges.

• Enoch et al 2010Enoch et al 2010– 0.1 M0.1 MJJ < Mp < 0.6 M < Mp < 0.6 MJJ

– MNRAS, in pressMNRAS, in press

– arXiv/1009.5917arXiv/1009.5917


Tidal heating?Tidal heating?• Circles: WASP Circles: WASP

planets, RV onlyplanets, RV only

• Dots: WASP Dots: WASP planets with low planets with low Lucy-Sweeney Lucy-Sweeney (1971) false-alarm (1971) false-alarm probability.probability.

• Triangles: Upper Triangles: Upper limits on limits on ee cos cos from secondary-from secondary-eclipse timing.eclipse timing.


Eccentricity versus Eccentricity versus KK• Poorly-Poorly-

constrained constrained orbits yield orbits yield spurious spurious eccentricities.eccentricities.

• Lucy & Sweeney Lucy & Sweeney (1971)(1971)

• Laughlin et al Laughlin et al (2005)(2005)

• Ford (2006)Ford (2006)


Why the prior increases with Why the prior increases with ee

e cos

e s

in


Circularization timescaleCircularization timescale• WASP planets WASP planets

with significant with significant eccentricity eccentricity detections detections

– Masses (MMasses (MJJ) in ) in parenthesesparentheses

• Triangles: Upper Triangles: Upper limits on limits on ee cos cos from secondary-from secondary-eclipse timing.eclipse timing.

– Mostly less Mostly less massive.massive.

• Cf. Goldreich & Cf. Goldreich & Soter (1966):Soter (1966):


Spin-orbit misalignmentsSpin-orbit misalignments• Measured via Rossiter-McLaughlin effect.Measured via Rossiter-McLaughlin effect.

– Winn et al (assorted)Winn et al (assorted)

• Misaligned and retrograde planets surprisingly common: Misaligned and retrograde planets surprisingly common: scattering/Kozai/tides?scattering/Kozai/tides?

– Triaud et al (2010); Wu & Murray 2003; Fabrycky & Tremaine 2007Triaud et al (2010); Wu & Murray 2003; Fabrycky & Tremaine 2007

• Aligned planets more prevalent around cool stars?Aligned planets more prevalent around cool stars?– Winn et al 2010 Winn et al 2010

• See talks by Josh Winn, Amaury Triaud (Wednesday)See talks by Josh Winn, Amaury Triaud (Wednesday)


Falling planets?Falling planets?• Levrard et al 2008:Levrard et al 2008:

• Close-in planets lack Close-in planets lack sufficient orbital sufficient orbital angular momentum to angular momentum to synchronize stellar spin synchronize stellar spin to orbit.to orbit.

• Tidal evolution leads to Tidal evolution leads to spiral-in.spiral-in.

• See talk on WASP-18b See talk on WASP-18b and WASP-19b by and WASP-19b by David Brown, Thursday. David Brown, Thursday.


ConclusionsConclusions• Ground-based surveys address the hottest gas-giant Ground-based surveys address the hottest gas-giant

planets orbiting bright, ~solar-type stars.planets orbiting bright, ~solar-type stars.

• Mass-radius relation Mass-radius relation – Low.mass planets: composition sequenceLow.mass planets: composition sequence

– High-mass planets: radius anomaly appears to be primarily an High-mass planets: radius anomaly appears to be primarily an irradiation effect.irradiation effect.

• Orbital eccentricity distribution shows parameter Orbital eccentricity distribution shows parameter dependences expected from circularization timescale.dependences expected from circularization timescale.

• Spin-orbit alignment more common around stars with Spin-orbit alignment more common around stars with outer convective zones.outer convective zones.

• Some of the closest-orbiting gas giants may spiral Some of the closest-orbiting gas giants may spiral into their host stars before the end of the main into their host stars before the end of the main sequence.sequence.


Host-star rotation - IHost-star rotation - I

Schlaufman 2010, ApJ 719, 602


Eccentricity, mass, obliquityEccentricity, mass, obliquity• 21 planets with projected obliquity measurements21 planets with projected obliquity measurements

– 15 aligned 15 aligned

– 3 inclined, prograde3 inclined, prograde

– 5 inclined, retrograde5 inclined, retrograde

Orbital eccentricity

Pla

net

mas

s in

Mj

Assorted works by Queloz, Winn, Wolf, Narita, Johnson, Bouchy, Hebrard, Cochran, Triaud, …


Host-star rotation - IIHost-star rotation - II

Schlaufman 2010, ApJ 719, 602


Stellar rotation and tidal evolutionStellar rotation and tidal evolution• For aligned systems:For aligned systems:

• Time to tidal spiral-in:Time to tidal spiral-in:– Hut 1980, 1981Hut 1980, 1981

– Dobbs-Dixon et al 2004Dobbs-Dixon et al 2004

– Levrard et al 2009Levrard et al 2009

• Main-sequence lifetime: Main-sequence lifetime:

€

Ω*

Ωorb

=Porb

P*

=Porbv sin I

2πR*

€

tremain =2Q*

'

117

M*

M p

⎛

⎝ ⎜ ⎜

⎞

⎠ ⎟ ⎟a

R*

⎛

⎝ ⎜

⎞

⎠ ⎟

5Porb

2π

€

tMS ≈10MSun

M*

⎛

⎝ ⎜

⎞

⎠ ⎟

3

Gyr


Short life expectancies?Short life expectancies?• For tidal dissipation factor Q=10For tidal dissipation factor Q=1066::

• Massive, eccentric planets have pseudo-synchronised Massive, eccentric planets have pseudo-synchronised host starshost stars

tremain / tMS

Ω* /

Ωo

rb

HD 17156b

HAT-P-2b

CoRoT-3b

WASP-18b

HD 80606b

XO-3b


Or inefficient tidal dissipation?Or inefficient tidal dissipation?• For tidal dissipation factor Q=10For tidal dissipation factor Q=1088::

tremain / tMS

Ω* /

Ωo

rb

HD 17156b

HAT-P-2b

CoRoT-3b

WASP-18b

HD 80606b

XO-3b


Tidal Tidal evolution: evolution: WASP-18bWASP-18b

• Using tidal evolution Using tidal evolution prescription of prescription of Dobbs-Dixon, Lin & Dobbs-Dixon, Lin & Mardling (2004)Mardling (2004)

63 Myr

1 Gyr

2 Gyr

5 Gyr

Hellier et al 2009

WASP-18

Hellier et al 2009


Small stars yield small planetsSmall stars yield small planets• HAT/WASP/XO/TrES: HAT/WASP/XO/TrES:

median host-star Tmedian host-star Teffeff is close to solar.is close to solar.

• Small planets easiest Small planets easiest to detect around to detect around smaller stars.smaller stars.

• Survey volume Survey volume contains few stars contains few stars cooler than ~4600K.cooler than ~4600K.

• Long data trains and Long data trains and careful photometric careful photometric extraction needed.extraction needed.

HAT-P-11bGJ436b

Host Star Teff

Pla

net

radi

us in

RJu

pC

umul

ativ

e pr

obab

ility


SummarySummary• WASP detection thresholds WASP detection thresholds

comparable to HAT, TrES, comparable to HAT, TrES, XO.XO.

• Bayesian candidate selection Bayesian candidate selection cuts down astrophysical cuts down astrophysical false positives.false positives.

• On-off photometry eliminates On-off photometry eliminates blended EBsblended EBs

• Still room for improvement:Still room for improvement:– Lens temperatureLens temperature– DIADIA– Multi-season BLS.Multi-season BLS.

• 16 planets found so far16 planets found so far– 8 per hemisphere8 per hemisphere

• Interesting trends emerging!Interesting trends emerging!


S. Aigrain (Cambridge -> Exeter)D. Anderson (Keele)S. Bentley (Keele)A. Carter (Open University)D.J. Christian (Belfast) W.I. Clarkson (Open University -> STScI) A. Collier Cameron (St Andrews) B. Enoch (Open University-> St Andrews)N.Gibson (Belfast) C.A. Haswell (Open University) L. Hebb (St Andrews)C. Hellier (Keele) K. Horne (St Andrews) J. Irwin (Cambridge -> CfA Harvard)Y. Joshi (Belfast)S.R. Kane (St Andrews -> Caltech) F.P. Keenan (Belfast) T.A. Lister (St Andrews/Keele -> LCOGT) P. Maxted (Keele)I. McDonald (Keele)A.J. Norton (Open University) J. Osborne (Leicester)N. Parley (Open University) D. Pollacco (Belfast) R. Ryans (Belfast) E. Simpson (Belfast) I. Skillen (ING) B. Smalley (Keele)A.M.S. Smith (St Andrews)I. Todd (Belfast)R.A. Street (Belfast -> LCOGT) R.G. West (Leicester) D.M. Wilson (Keele)P.J. Wheatley (Leicester -> Warwick)

SuperWASPWide Angle Search for Planets

With:F. Bouchy (IAP)G. Hébrard (IAP)F. Pont (Geneva->Exeter)B. Loeillet (Marseille)M. Gillon (Geneva)M. Mayor (Geneva)C. Moutou (Marseille)F. Pepe (Geneva)D. Queloz (Geneva)A.M.H.J. Triaud (St Andrews -> Geneva)S. Udry (Geneva)


WASP: stellar number densityWASP: stellar number density


Systematics and Systematics and red noisered noise

• Systematics:Systematics:– Secondary extinctionSecondary extinction

– Temperature-dependent Temperature-dependent focusfocus

– Sky brightness-dependent Sky brightness-dependent bias in background bias in background subtractionsubtraction

– SysRem: Tamuz et al 2005SysRem: Tamuz et al 2005

– TFA: Kovacs et al 2005TFA: Kovacs et al 2005

• Red noise:Red noise:– Pont et al 2006Pont et al 2006

– Smith et al 2006Smith et al 2006

RMS scatterRMS scatter (real data, 2.5-hr bins)RMS scatter (white noise, 2.5-hr bins))

RMS scatterRMS scatter (real data, 2.5-hr bins)RMS scatter (white noise, 2.5-hr bins))


Planet-catch simulationsPlanet-catch simulations• Smith, A M S et al, 2006Smith, A M S et al, 2006

• Besançon model: Besançon model: – V, TV, Teffeff, [Fe/H], [Fe/H]

• P(P(planet) = planet) = 0.03x100.03x102.0[Fe/H]2.0[Fe/H] – Fischer & Valenti 2005Fischer & Valenti 2005

• Linear CDF in log aLinear CDF in log a• Transit probability ~ Transit probability ~

RR**/a/a• Inject fake Jupiter-Inject fake Jupiter-

sized planet transits sized planet transits into real WASP light into real WASP light curves.curves.


Red noise and planet catchRed noise and planet catch

Season 1

Season 2


SensitivitySensitivity

• Transit depth Transit depth threshold:threshold:

– 0.01 mag@V=110.01 mag@V=11

– 0.015 mag@V=120.015 mag@V=12


Measurable parametersMeasurable parameters• Winn 2008, IAU Symp. 253Winn 2008, IAU Symp. 253

iau symposium 276 -- torino, 12 october 2010 statistical patterns in ground-based transit surveys...

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