Transits from Space: 1. The CoRoT mission

Why do Transit searches from Space? 1.No scintillation noise → One can reach the photon limit 2. No atmospheric extinction → Less false positives 3. Continous temporal coverage → if a stars shows a transit you will find it! In short: the light curves are of better quality, have better temporal coverage so you can find smaller transits and transits in long period orbits

Disadvantages of Space 1.If the launch fails you do not get a second chance 2.If your instrument breaks, you cannot fix it 3. Space environment introduces different problems in the light curve analysis 4. It is expensive!

The CoRoT Mission (CNES) COnvection ROtation and Planetary Transits Goals: exoplanets + astroseismology Polar Earth orbit 27 cm Telescope w/ 4 CCD detectors 2.8° x 2.8° field-of-view Max 150 days observing runs Launched: 27th December 2006 Participation from: F, A, B, D, E, ESA, Brasil Duration 6+ years

CoRoT was successfully launched from Baikanur on 27 December kg kg water

The Launch Profile of CoRoT: if (WWIII) then White House., U.S.A else if (corot) then orbit end if Washington, D.C. orbit Baikanur.

a = km e = i = The Orbit of CoRoT a = km e = i = P orb = 6176 – 6195 s → The orbit is nearly perfect GoalReality

The eyes of CoRoT Movie time!

Focal Plane: PSF: Astroseismology PSF: exo-Planet CoRoT-Mission: Focal Plane 2.8 o x 1.4 o Seismo field: ~10 targets/CCD 5 < V < 9.5 Exofield field: ~ 6000 targets/CCD 11 < V < 16

CoRoT does not download the entire CCD images, but only the data in an aperture centered on the star 32 sec integrations. On-board summing of data in aperture plus binning to 512 s exposure time. On-board processing returns only integrated flux in aperture. 400 „oversampled“ apertures with 32 s sampling. This can be changed during the run ~ 40 imagettes. Data from the full image inside the aperture is sent back Chromatic information (CoRoT r,g,b) for only about ½ of the brightest stars (chromatic and monochromatic light curves) ~6000 apertures per exo-CCD. If more stars are in the field one has to decide before which stars to observed (proposals) Exofield Information

The South Atlantic Anomaly (SAA) Duty Cycle: Not completely continuous coverage ~ 6% of the data is lost due to the SAA other „random events“ cause 1-2% loss Duty cycle ~ 92%

Sample Light Curves from the Exofield Showing Stellar Variability

So is all this effort worth going to Space? An OGLE transit discovery (ground-based) A CoRoT transit discovery

The CoRoT Ground-based Follow-up Effort CoRoT only finds transit „candidates“. An extensive ground-based effort is required to confirm that this is indeed a planet. For Space-based transit searches, Ground-based observations are „part of the Mission“ But before the ground-based follow up starts one needs to do the best possible analysis on the light curve to give the best candidates. Much information comes from the light curves e.g.: Is the transit too long : probably a giant Do you see a secondary? Probably an eclipsing binary

Problem : The size of the CoRoT aperture The CoRoT PSF can have up to 0-20 background stars whose light contaminates the light of the primary star. The first step is to identify which star is making the transit We will go through the necessary procedures to confirm the planet for the case of CoRoT-7b!

Status of CoRoT CoRoT has been operating for over 4 years Over 110,000 stars have been observed 24 Transiting Planets have been discovered CoRoT mission has been extended for 3 years until the end of 2013 On 7 March 2009 CoRoT lost DPU1 (Data Processing Unit) that controlled one Exoplanet and one Seismo CCD. CoRoT continues to work well, but only getting data on ½ the original number of stars On 6 March 2009 NASA Launched Kepler

The first six CoRoT planets: CoRoT-1b CoRoT-3bCoRoT-2b Deleuil et al. 2008Barge et al. 2008Alonso et al CoRoT-4b Agrain et al. and Moutou et al CoRoT-5b Rauer et al., A&A 2009 CoRoT-6b Fridlund et al., A&A 2009 P: days R: 1.49 R J m: 1.03 M J  : 0.38 cgs P: days R: 1.49 R J m: 1.03 M J  : 0.38 cgs P: days R: R J m: 3.31 M J  : 1.3 cgs P: days R: R J m: 3.31 M J  : 1.3 cgs P: days R: 1.01 R J m: M J  : 26.4 cgs P: days R: 1.01 R J m: M J  : 26.4 cgs P: days R: 1.19 R J m: 0.72 M J  : 0.5 cgs P: days R: 1.19 R J m: 0.72 M J  : 0.5 cgs P: days R: 1.28 R J m: M J  : 0.22 cgs P: days R: 1.28 R J m: M J  : 0.22 cgs P: 8.88 days R: 1.15 R J m: 3.3 M J  : 2.3 cgs P: 8.88 days R: 1.15 R J m: 3.3 M J  : 2.3 cgs

And the next 6 CoRoT-7b Deleuil et al Barge et al CoRoT-9b CoRoT-8b CoRoT-11b CoRoT-10bCoRoT-12b Gandolfi et al Bonnono et al Borde et al P: 0.85 days R: 0.14 R J m: 0.02 M J  : 10.1 cgs P: 0.85 days R: 0.14 R J m: 0.02 M J  : 10.1 cgs P: 95 days R: 1.05 R J m: 0.84 M J  : 0.9 cgs P: 95 days R: 1.05 R J m: 0.84 M J  : 0.9 cgs P: 6.2 days R: 0.57 R J m: 0.22 M J  : 1.6 cgs P: 6.2 days R: 0.57 R J m: 0.22 M J  : 1.6 cgs P: 13.2 days R: 0.97 R J m: 2.75 M J  3.7 cgs P: 13.2 days R: 0.97 R J m: 2.75 M J  3.7 cgs P: 3.0 days R: 1.43 R J m: 2.33 M J  1.0 cgs P: 3.0 days R: 1.43 R J m: 2.33 M J  1.0 cgs P: 2.8 days R: 1.44 R J m: 0.91 M J  0.8 cgs P: 2.8 days R: 1.44 R J m: 0.91 M J  0.8 cgs Gillon et al. 2010

CoRoT-13b Bouchy et al Cabrera et al CoRoT-15b CoRoT-14b P: 4.0 days R:0.88 R J m: 1.31 M J  : 2.3 cgs P: 4.0 days R:0.88 R J m: 1.31 M J  : 2.3 cgs P: 3.1 days R: 1.12 R J m: 63 M J  : 59 cgs P: 3.1 days R: 1.12 R J m: 63 M J  : 59 cgs P: 1.5 days R: 1.1 R J m: 7.6 M J  : 7.3 cgs P: 1.5 days R: 1.1 R J m: 7.6 M J  : 7.3 cgs Tingley et al In preparation: CoRoT-16b – 24b

RM anomaly CoRoT-1b and its Rossiter-McLaughlin effect

CoRoT-2b : A Hot Jupiter around an active star Alonso et al P: days R: R J m: 3.31 M J  : 1.3 cgs P: days R: R J m: 3.31 M J  : 1.3 cgs

CoRoT-3b : The First Transiting Brown Dwarf P: days R: 1.01 R J m: M J  : 26.4 cgs P: days R: 1.01 R J m: M J  : 26.4 cgs

Planets Pressure support provided by electron degeneracy pressure, no fusion (M < 13 M Jup ) Stars Hydrogen fusing in hydrostatic equilibrium (M > 80 M Jup ) Brown Dwarfs Pressure support provided by electron degeneracy pressure, short period of deuterium burning (13 < M < 80 M Jup )

Modified From H. Rauer CoRoT-3b : Radius = Jupiter, Mass = 21.6 Jupiter CoRoT-1b : Radius = 1.5 Jupiter, Mass = 1 Jupiter OGLE-TR-133b: Radius = 1.33 Jupiter, Mass = 85 Jupiter CoRoT-1b CoRoT-3b OGLE-TR-133b

CoRoT-9b, the first well-known temperate exoplanet - longest period planet detected by transits (at time of announcement) - moderate temperate gas giant - low eccentricity, thus moderate temparature variations along orbit Deeg et al., Nature 2010 CoRoT-9b: - R = 1.05 R J - P = d - a = AU - e = m = 0.84 M J - Density = 0.9 gm cm –3 - Teff = 250 – 400 K

In spite of rotational modulation due to spots with a photometric amplitude of ~2% one can find… CoRoT-7b : The Crown Jewel of CoRoT

0.035% CoRoT-7b : The Crown Jewel of CoRoT Transit Curve CoRoT-7b: - R pl = 1.6 R    P = d - a = AU - m = 7.4 M Earth CoRoT-7b: - R pl = 1.6 R    P = d - a = AU - m = 7.4 M Earth Leger et al., 2009; Queloz et al. 2009, Hatzes et al. 2010

The „Sherlock Holmes Proof“ Or why we knew CoRoT-7b was a planet before we had radial velocity measurements. Hypothesis #1: The transit is caused by a contaminant On-off photometry established that nearby stars could not account for transit depth of CoRoT-7

Hypothesis #2: The star is really a giant star No, it is a G8 Main Sequence Star

Hypothesis #3: There is a faint very nearby background eclipsing binary star that causes the eclipse Adaptive Optics Imaging shows no very close companions

Hypothesis #4: A Hiearchical Triple system with 2 eclipsing M-dwarfs, Short period M dwarfs are very active and we would have seen Ca II emission from the binary stars and X-ray emission

Hypothesis #5:The transit is caused by a background (or binary companion) M dwarf with a transiting Hot Jupiter 1. Giant planets to M dwarfs are rare 2 The M dwarf is bright in the Infrared. High resolution infrared spectral observations show no evidence for an M dwarf companion.

There are only two astronomical bodies that have a radius ~ 1 R Earth : 1.White Dwarf 2. A terrestrial planet White Dwarfs have a mass of ~ 1 Solar Mass, so the radial velocity amplitude should be ~ 100s km/s. This is excluded by low precision radial velocity measurements. „Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.” - Sherlock Holmes

44 RV (m/s) JD CoRoT-7 is an active star with an RV jitter twice that the expected RV planet from the star P rot = 23 d

A carefull analysis shows that you can extract the planet signal from the activity signal  O–C = 1.7 m/s  RV = 1.8 m/s CoRoT-7b P = 0.85 d Mass = 7.3 M Earth

50

T surface ~ 1800 – 2600 C A lava ocean planet?

Art predicting reality? There is a popular German SF-series where a Lava planet - called Daa’mur – populated by exotic life forms which evolved from thermophile. Therefore its funny that the first transiting rocky planet (CoRoT-7b) fits in such a Lava- planet category.

The CoRoT-7 Planetary System P = 3.7 Days Mass = 12.4 M E CoRoT-7c P = 9 Days Mass = 16.7 M E CoRoT-7d The analysis of the radial velocity measurements reveals the presence of 2 additional planets. So why do these not transit?

10 o Only CoRoT-7b Transits CoRoT-7b,c,d

Mercury Mars Venus Earth Moon CoRoT-7b Radius (R Earth )  (gm/cm 3 ) Kepler-10b No iron Earth-like Iron enriched From Diana Valencia