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Important discoveries from Ground-based Transit Surveys Charbonneau et al. (2000): The observations that started it all: • • • • Proof that RV variations are due to planet Mass = 0,63 MJupiter Radius = 1,35 RJupiter Density = 0,38 g cm–3 GJ 436: The First Transiting Neptune Host Star: Mass = 0.4 M( סּM2.5 V) Butler et al. 2004 MEarth-1b: A transiting Superearth D Charbonneau et al. Nature 462, 891-894 (2009) doi:10.1038/nature08679 Lower bound r = 0.15 gm cm–3 Upper bound r = 3 gm cm–3 Both RV and Transit Searches show a peak in the Period at 3 days The ≈ 3 day period may mark the inner edge of the proto-planetary disk Radius (RJ) Mass-Radius Relationship Mass (MJ) Radius is roughly independent of mass, until you get to small planets (rocks) Summary of Global Properties of Transiting Planets 1. Transiting giant planets (close-in) tend to have inflated radii (much larger than Jupiter) 2. The period distribution of close-in planets peaks around P ≈ 3 days for both RV and transit discovered planets. 3. Most transiting giant planets have densities near that of Saturn. It is not known if this is due to their close proximity to the star (i.e. inflated radius) 4. Transiting planets have been discovered around stars fainter than those from radial velocity surveys Transits from Space: CoRoT and Kepler 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 Sources of Errors Atmospheric Extinction Atmospheric Extinction can affect colors of stars and photometric precision of differential photometry since observations are done at different air masses. To remove tranparency effects one has to reference the light level of your target star to a „constant“ star. 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! ~25.000 Euros 150.000.000 Euros 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 2006 630 kg + 1000 kg water CoRoT is a dual-purpose mission: Asteroseismology and Exoplanets Seismo field: ~10 targets/CCD Exofield field: ~ 6000 targets/CCD 5 < V < 9.5 11 < V < 16 CoRoT-Mission: Focal Plane Focal Plane: PSF: Astroseismology 2.8o x 1.4o secondary target * * main target * * faint stars (11-16) targets / CCD PSF: exo-Planet * * * * * Asteroseismologie channel Field of view Exoplanets channel The 4 CCD detectors of CoRoT. Two are devoted 2 are devoted to exoplanets and 2 to asteroseismology The eyes of CoRoT Duty Cycle: Not completely continuous coverage The South Atlantic Anomaly (SAA) • ~ 6% of the data is lost due to the SAA • other „random events“ cause 1-2% loss • Duty cycle ~ 92% Relative Flux Relative Flux The SAA also creates challenges in the data reduction: Discontinuities JD-2400000 JD-2400000 • Proton events associated with SAA crossing • Affects lightcurves in the starflux and/or background subtraction • On-board software modified to treat hot pixels in the background subtraction 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 Follow-up facilities: if it collects photons, we will use it! Step 1: Get on-off Photometry to Identify the Star responsible for the Transit Telescopes used for Photometric Followup CoRoT-3b was on target! Step 3: Get Radial Velocity Measurements to determine the mass Sometimes it turns out to be a low-mass star M ~ 0.15 Mסּ Step 4: Correct the CoRoT light curve for contaminants The background stars contribute to the light measured by CoRoT. One has to correct the light curve for these contaminants. One has to know all the stars, and their brightness that lie in the CoRoT aperture. Status of CoRoT • CoRoT operated for over 6 years • Over 200,000 stars have been observed • 32 Transiting Planets have been discovered • CoRoT mission was extended for 3 years until the end of 2015, but…. • On 7 March 2009 CoRoT lost DPU1 (Data Processing Unit) that controlled one Exoplanet and one Seismo CCD. CoRoT continued to work well, but only getting data on ½ the original number of stars • On 2 November 2012 CoRoT lost the second DPU CoRoT-3b : The First Transiting Brown Dwarf P: 4.2568 days R: 1.01 RJ m: 21.66 MJ r: 26.4 cgs Planets Stars Pressure support provided by electron degeneracy pressure, no fusion (M < 13 MJup) Hydrogen fusing in hydrostatic equilibrium (M > 80 MJup) Brown Dwarfs Pressure support provided by electron degeneracy pressure, short period of deuterium burning (13 < M < 80 MJup) CoRoT-1b OGLE-TR-133b CoRoT-3b 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 Modified From H. Rauer CoRoT-7b In spite of rotational modulation due to spots with a photometric amplitude of ~2% one can find… CoRoT-7b : The Crown Jewel of CoRoT Transit Curve 0.035% CoRoT-7b: - Rpl = 1.6 R -P = 0.8536 d - a = 0.017 AU Leger et al., 2009; Queloz et al. 2009, Hatzes et al. 2010 RV (m/s) CoRoT-7 is an active star with an RV jitter twice that the expected RV planet from the star JD Prot = 23 d 44 CoRoT-7b sO–C = 1.7 m/s sRV = 1.8 m/s P = 0.85 d Mass = 7.3 MEarth A carefull analysis shows that you can extract the planet signal from the activity signal CoRoT-7b The CoRoT-7 Planetary System CoRoT-7c P = 3.7 Days Mass = 12.4 ME CoRoT-7d P = 9 Days Mass = 16.7 ME The analysis of the radial velocity measurements reveals the presence of 2 additional planets. So why do these not transit? CoRoT-7b,c,d 10o Only CoRoT-7b Transits r ~ M1.17 from wikipedia The Kepler Mission 55 The Kepler Mission (NASA) • Goal: detect Earth-sized planet in HZ • Orbit: Earth Trailing • 0.95 m aperture Schmidt telescope • 42 CCD detectors • 105 square degree field of view • Stare at one star field of 100,000 stars • Duration: 4 years Launched: March 6, 2009 • Failed in May 2013 Kepler 2 56 Kepler detectors. Note that they are on a curved surface. This is because the focal plane for a Schmidt telescope is a sphere. Status of Kepler • Kepler has collected data for over 4 years • Over 170,000 stars have been observed • 962 Transiting planets discovered so far (not all confirmed by Doppler measurements •In May 2013 it lost a second reaction wheel and is no longer able to point precisely enough to detect Earthlike planets • In Spring 2014 Kepler will begin a new mission: observe fields in the ecliptic for 2 months Kepler‘s First Giant Planet Discoveries Kepler-4b P = 3.21 d MP =0.077MJ RP = 0.36 RJ r (gm cm–3) = 1.91 Kepler-5b P = 3.55 MP =2.11 MJ Rp = 1.43 RJ r (gm cm–3) = 0.89 Kepler-6b P = 3.23 MP =0.67 MJ Rp = 1.32 RJ r (gm cm–3) = 0.35 Kepler 7b: The „Foam“ planet Period: 4.88 d Mass: 0.433 MJup Radius: 1.84 RJup Density: 0.16 gm cm–3 The inner structure of Kepler-10b and CoRoT-7b CoRoT-7b Kepler-10b r(gm/cm3) 10 7 Earth Mercury 5 4 3 Venus Mars Moon 2 From Diana Valencia 1 0.2 0.4 0.6 0.8 2 1 1.2 1.4 Radius (REarth) 1.6 1.8 A new class: Circumbinary Planets Kepler 16(AB)b Pbinary = 41 days Pplanet = 229 days Mplanet = 0.33 MJ Rplanet = 0.75 RJ The Circumbinary Planets Kepler 16 Binary Planet b MA = 0.69 M Pb = 229 d MB = 0.20 M Rb = 0.75 RJ PAB = 41 d mb = 0.33 MJ Kepler 35 Binary Planet b MA = 0.89 M Pb = 131.4 d MB = 1.02 M Rb = 0.78 RJ PAB = 20.7d mb = 0.13 MJ Kepler 34 Binary Planet b MA = 1.05 M Pb = 288 d MB = 1.02 M Rb = 0.22 RJ Pbinary = 27.8 d mb = 0.76 MJ Kepler 38 Binary Planet b MA = 0.95 M Pb = 105.6 d MB = 0.25 M Rb = 0.39 RJ PAB = 18.8 d mb < 0.38 MJ Sometimes Hollywood gets it right! Multiple Transiting Planets: Kepler 11b-g M = 4,2 ME M = 13 ME M = 6,36 ME M = 8,3 ME M = 2,2 ME M < 300 ME With multiple planets around faint stars it is difficult to get the planet mass with radial velocity measurements. It takes too much data. However, Kepler can use transit timing variations (TTVS). TTVs are caused by the mutual gravitation interaction with the planets and using dynamical simulations you can determine the mass. Planet e has a shorter transit duration than expected because it is more inclined Distribution of planets Kepler-22b: „A superearth in the Habitable Zone Kepler-22b Radius = 2,38 REarth Mass < 36 MEarth Period = 290 days Distance to Star = 0,89 AU Temperature = 262 K Kepler-22 in comparison to our Solar System Kepler-186: The „First“ Earth-sized Planet in the Habitable Zone Qunitana et al. 2014 Radius of Planet = 1.11 ± 0.14 MEarth Leuchtkraft gegen Alter (Sterne, braune Zwerge und Planeten) Sterne leuchten selbst, Planeten nicht, junge Planeten doch etwas Deuterium-Brennen: D(p,g)He Fusoren Sterne: H(p,e n)D(p,g)He log L / Lsun + Braune Zwerge 0.078 Suns = 78 Jupiter Planeten (= Nicht-Fusoren) 13 Jup Jupiter Simple Definition: Objekte mit weniger als 13 Jupitermassen sind Planeten, falls entstanden im Orbit um einen Fusor.. (Burrows et al. 1993, 1997 ApJ) log Age (years) Naos-Conica: Nasmyth Adaptive Optics System & Coude optical and near-infrared camera Unit Teleskop 4 YEPUN Sinfoni: Spectrograph for Integral field Observations in the near Infrared Direkte Detektion von Exo-Planeten: Problem der Dynamik TWA-5 B 3.5m-NTT (Sofi) TWA-5 B 8.2m-VLT (Fors2) Abstand zum Stern: z.B. 10 AE (1 arc sec in 10 pc) (0.2 arc sec in 50 pc) Problem der Dynamik: Stern viel zu hell und viel zu nah !!! PZ Tel 12 Myrs NACO Ks-band S13 (in b Pic group) N 0.5'' E Mugrauer et al. 2010 A&A Speckle Technik / Speckle imaging Tausende von sehr kurzen (Millisekunden) Belichtungen, die addiert werden (shift + add). Belichtung kürzer als Korrelationszeitskala der Erdatmosphäre (~ 60 ms). Speckle: Shift + Add: 3.5m New Technology Telescope (NTT) ESO, La Silla, Chile Lucky Imaging in Jena (wie Speckle imaging, aber im roten Optischen) RTK no filter raw frames (t=0.05s) 5 arcsec Lucky Imaging in Jena (wie Speckle imaging, aber im roten Optischen) RTK no filter simple add 5 arcsec Lucky Imaging in Jena (wie Speckle imaging, aber im roten Optischen) RTK no filter shift+add 5 arcsec Lucky Imaging in Jena (wie Speckle imaging, aber im roten Optischen) RTK no filter Lucky Imaging 10% 5 arcsec Lucky Imaging in Jena (wie Speckle imaging, aber im roten Optischen) RTK no filter Lucky Imaging 5% 5 arcsec Seeing und adaptive Optik Auflösung = Wellenlänge l / Spiegelgröße D Seeing limitiert ! Seeing durch Turbulenz in der Erdatmosphäre, korrektur durch AO. Adaptive Optics (AO): Adapt optics (one mirror) to to turbulence in atmosphere r_0 = r_0(l) Größe des kohärenten Teils der Wellenfront (1.2m @ 2.2 mm), t_0 = t_0(l) Kohärenzzeit (10 ms @ 2.2mm), Strehl Verhältnis = Maximum in beob. Bild (0…1) / erwartet für perfekte Optik Bestätigung (visueller) stellarer Begleiter HR 7329 (VLT/Isaac) TWA 5 (VLT/Fors) Braune Zwerg Begleiter ! (mehrere braune Zwerg Begleiter, inklusive Den ersten drei unter den Vorhauptreihensternen) (Guenther & Neuhäuser 2001) (Neuhäuser et al. 2000) HD 130948 (Gemini/Hokupaa) (Neuhäuser et al. 2002) (Potter, ..., Neuhäuser 2002 ApJ) AO Instrument Hokupa´a am Gemini 8.3m 55 masProc.) binary ! Mauna Kea, (Neuhäuser, Potter,Hawai´i Brandner 2001 Conf. TWA-5 A & B: FWHM = 0.064 arc sec, 30% Strehl (H-Band) H=17 at 1“ (5 Jup, 60 AU) Bestes mit VLT/FORS: 0.180 arc sec (Potter, ..., Neuhäuser 2002 ApJ) Gemini-North 8.3m HD 130948 (200 Mio. Jahre, UMa cluster) mit 2 Braunen Zwergen (frühes-L, H=12), Abstand 0.13“ = 2.5 AE bei 18 pc. 10 Jahre Orbit, dann Massen dynamisch ! Tachihara et al. 1996, PASJ 48 Datenreduktion im Infraroten: Problem ist warme = helle Erdatmosphäre Bild – Bias Flat - Bias 2) Abzug des Hintergrundes: 3) Schieben: Bild_1 - Bild_2 Shift Bild_1 - Bild_2 Bild_2 - Bild_3 Shift Bild_2 - Bild_3 Bild_3 - Bild_4 Shift Bild_3 - Bild_4 4) Addieren: 1) Rohbilder: Bild_1 Bild_2 Beipiel: GQ Lupi Bild_3 Neuhäuser et al. 2005 Sehr viele Bilder … (1000 x 1000 pixel) etc … etc … Shift+add von 5400 x 0.3 sec =5400x4.4 Mbyte Daten-Reduktion: shift + add SofI/NTT (H-Band) SofI/NTT SofI/NTT (H-Band) (H-Band) NTT Raw SofI Jitterframe 50x1.2s 10 Raw SofI Specialdomeflat frames (50x1.2s) shift+add 50 x 1.2 sec Ergebnisbild 10 Bilder per shift + add Eigenbewegungsanalyse „Direkt-Imaging“ – Methode u And Spektroskopisch 55 Cnc CT Cha: 1 Mio Jahre junger Stern im Sternbild Chamäleon am Südhimmel (540 Lichtjahre Entfernung) VLT / Sinfoni J, H, K, H+K-Band Spektren: Auflösung: R=1500 - 4000 J-Band H-Band K-Band CT Cha b und Drift-Phoenix: J T= 2600 ± 250 K AV= 5.2 ± 0.8 mag Mag, AV und Distanz geben Leuchtkraft L (log(L/Lʘ)= -2.68 ± 0.21) H L and T gibt Radius (~ 2.2 ± 0.7 RJup) T, L, Alter gibt die Masse: ~ 17 ± 6 MJup K aber Modellabhängig (Planet oder Brauner Zwerg ?) Lodieu et al. 2008 UScoJ160714-232101 AV=2.1 mag Schmidt, Neuhäuser, Seifahrt et al. 2008 A&A GQ Lup 0.7 arcsec Fomalhaut b HST 0.6 mm 12.7“ = 115 AU (Kalas et al. 2008) Belt inner edge at 133 AU (with e = 0.11) Upper mass limit 3 M_jup due to disk ring HR 8799 b 1.73“ = 68 AU c 0.95“ = 38 AU d 0.63“ = 24 AU Marois et al. 2008 beta Pic b: Lagrange et al. 2009, 2010: 6 – 13 Jup Massen bei 8.6 AE Scheibenlücke Freistetter, Krivov, Löhne, 2007 sagten einen 2 - 5 Jup Massen Planet Bei rund 12 AE (7 – 16 AE) um Beta Pictoris in einer Scheibenlücke mit Hilfe von Stabilitätsberechnungen voraus 2003 2009 Zukunft Geplantes E-ELT – 39 m Durchmesser 978 m2 Fläche – 800 Spiegelsegmente Beobachtungsbeginn ~ 2020 Darwin/Terrestrial Path Finder hätten Nulling Interferometrie benutzt Earth Venus Mars Ground-based European Nulling Interferometer Experiment wird die Nulling Interferometrie am VLTI testen Voyager 1 Sonde (am 5. September 1977 gestartet) nahm 1990 ein Bild der Erde auf – aus ca. 6,4 Milliarden km Entfernung = 43 Astronomische Einheiten = 0,00002 Lichtjahre
