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Hubble Science Briefing. Exoplanet Atmospheres: Insights via the Hubble Space Telescope. Nicolas Crouzet 1 , Drake Deming 2 , Peter R. McCullough 1 1 Space Telescope Science Institute 2 University of Maryland May 2, 2013. The Solar system. Sizes to scale Distances NOT to scale.
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Hubble Science Briefing Exoplanet Atmospheres: Insights via the Hubble Space Telescope Nicolas Crouzet 1, Drake Deming 2, Peter R. McCullough 1 1 Space Telescope Science Institute 2University of Maryland May 2, 2013
The Solar system Sizes to scale Distances NOT to scale 8 planets in the Solar system: Mercury , Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune 2 Hubble Science Briefing 5/2/13
A revolution!! The first exoplanet: 51 Peg b (Mayor & Queloz 1995) 51 Peg b: Mass ≈ 0.5 Jupiter masses Orbital period = 4.2 days!! 3 Hubble Science Briefing 5/2/13
How do we detect exoplanets? The radial velocity method Indicates the mass of the planet 4 http://media4.obspm.fr/exoplanetes/pages_exopl-methodes/vitesses-radiales.html credit Emmanuel Pécontal Hubble Science Briefing 5/2/13
How do we detect exoplanets? The radial velocity method Indicates the mass of the planet 5 http://media4.obspm.fr/exoplanetes/pages_exopl-methodes/vitesses-radiales.html credit Emmanuel Pécontal Hubble Science Briefing 5/2/13
How do we detect exoplanets? The radial velocity method Indicates the mass of the planet 6 http://media4.obspm.fr/exoplanetes/pages_exopl-methodes/vitesses-radiales.html credit Emmanuel Pécontal Hubble Science Briefing 5/2/13
How do we detect exoplanets? The radial velocity method Indicates the mass of the planet 7 http://media4.obspm.fr/exoplanetes/pages_exopl-methodes/vitesses-radiales.html credit Emmanuel Pécontal Hubble Science Briefing 5/2/13
How do we detect exoplanets? The radial velocity method Indicates the mass of the planet 8 http://media4.obspm.fr/exoplanetes/pages_exopl-methodes/vitesses-radiales.html credit Emmanuel Pécontal Hubble Science Briefing 5/2/13
How do we detect exoplanets? The radial velocity method Indicates the mass of the planet 9 http://media4.obspm.fr/exoplanetes/pages_exopl-methodes/vitesses-radiales.html credit Emmanuel Pécontal Hubble Science Briefing 5/2/13
How do we detect exoplanets? The transit method Indicates the radius of the planet 10 Hubble Science Briefing 5/2/13
How do we detect exoplanets? The imaging method HR 8799 (Marois et al. 2008, 2010) Direct detection of exoplanets 11 Hubble Science Briefing 5/2/13
Historical background The discovery of exoplanets 12 Hubble Science Briefing 5/2/13
Historical background 1995: The first exoplanet around a Sun-like star, 51 Peg b Mayor & Queloz 1995 13 Hubble Science Briefing 5/2/13
Historical background 1999: The first transiting exoplanet, HD 209458 b Charbonneau et al. 2000 14 Hubble Science Briefing 5/2/13
Historical background 2008: Direct imaging of Fomalhaut b and HR8799 b Marois et al. 2008 Kalas et al. 2008 15 Hubble Science Briefing 5/2/13
Historical background 2009: The first transiting super-Earth, CoRoT-7 b Léger et al. 2009 16 Hubble Science Briefing 5/2/13
Historical background 2012: The first Earth-size exoplanets, Kepler 20 e & f Fressin et al. 2012 17 Hubble Science Briefing 5/2/13
Historical background The discovery of exoplanets As of April 30th, 2013: 880 exoplanets: 132 in multiple systems 308 transiting 18 Hubble Science Briefing 5/2/13
Historical background And probably millions more… 19 Hubble Science Briefing 5/2/13
Detection and characterization Basics Detection = Finding planets Characterization = Studying in detail individual planets, after their detection Requires a bright host star to maximize the signal Currently only a few exoplanets can be characterized 20 Hubble Science Briefing 5/2/13
The power of the transit method 21 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope Image of the target star on the detector HST has several spectrographs on board 22 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope Spectrum: Measure of the light at different wavelengths Variations reveal absorption by molecules in the atmosphere of the planet Absorption Wavelength 23 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope First detection of an exoplanet atmosphere… … that is escaping HD209458b - HST STIS (Charbonneau et al. 2002) HD209458b - HST STIS (Vidal-Madjar et al. 2003, 2004) Excess absorption 24 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope The NICMOS controversy NICMOS: Near Infrared Camera and Multi-Object Spectrometer onboard Hubble Space Telescope Methane and water in the atmosphere of HD198733b (Swain et al. 2008) 25 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope The NICMOS controversy HD189733b A new look at NICMOS transmission spectroscopy of HD 189733, GJ-436 and XO-1 “No conclusive evidence for molecular features” (Gibson et al. 2011) 26 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope The NICMOS controversy Need more observations 27 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope But NICMOS became unavailable… New instruments installed on HST, including Wide Field Camera 3 (WFC3) Installation by a team of astronauts in May, 2009 28 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope WFC3 observations of HD 189733: coming this year… 29 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope HD 209458 b Sodium in an escaping atmosphere, detected by HST Why is sodium important? • A key to distinguish between 2 classes of hot-Jupiters as proposed by theoretical models (Fortney 2008, 2010) • Strongly irradiated hot-Jupiters: - planet is very hot (~ 2000 to 5000°F) • - large day-night temperature contrast • - do not show sodium in their atmosphere • Less irradiated hot-Jupiters: - planet is cooler (less than 2000°F) • - more redistribution of heat around the planet • - show sodium in their atmosphere Sodium helps to understand the general characteristics of hot-Jupiters 30 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope HD 209458 b Recent observations with HST WFC3 (Deming et al. 2013) Best precision ever achieved for exoplanetspectroscopy (40 parts per million) Detection of water vapor in the planet’s atmosphere! (signal: 200 parts per million) 31 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope HD 209458 b But water vapor signal is smaller than expected! Interpretation: Presence of clouds and/or haze in the planet’s atmosphere, that weaken the signal 32 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope HD 209458 b But water vapor signal is smaller than expected! Interpretation: Presence of clouds and/or haze in the planet’s atmosphere, that weaken the signal HST provides clues about HD 209458 b’s atmosphere: water vapor, with clouds and/or haze 33 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope GJ 1214 b A transiting super-Earth or mini-Neptune (Charbonneau et al. 2009) Radius = 2.7 RE Mass = 6.6 ME Density = 1.9 g/cm3 (Earth: 5.5 g/cm3) Marcy 2009 34 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope GJ 1214 b Berta et al. 2012 - HST WFC3 Bean et al. 2010 - Ground based observations The spectrum is flat!! 35 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope GJ 1214 b Inconsistent with a cloud-free extended atmosphere Atmosphere has to be “heavy” (high molecular weight)… But it might also be a very cloudy atmosphere 36 Hubble Science Briefing 5/2/13
Transit spectroscopy with the Hubble Space Telescope GJ 1214 b Inconsistent with a cloud-free extended atmosphere Atmosphere has to be “heavy” (high molecular weight)… But it might also be a very cloudy atmosphere Still an open question… On-going HST program for more observations 37 Hubble Science Briefing 5/2/13
The future Transiting Exoplanet Survey Satellite (TESS) NASA Mission for launch in 2017 Principal Investigator: George Ricker (MIT) Aim: Discover Transiting Earths and Super-Earths orbiting bright, nearbystars 38 Hubble Science Briefing 5/2/13
The future The James Webb Space Telescope (JWST) JWST… a big thing!! Mirror: 6.5 meters (21 feet) in diameter Observations in the infrared Orbit about 1.5 million km (1 million miles) from the Earth Launch: goal 2018 39 Hubble Science Briefing 5/2/13
The future The James Webb Space Telescope (JWST) Predicted performances: Example of carbon dioxide in a habitable SuperEarth 40 Hubble Science Briefing 5/2/13
Conclusion The transit method is the most powerful to characterize exoplanets HST plays a major role in transit spectroscopy These observations bring information about molecules, clouds, and haze in the atmosphere of exoplanets The future: TESS and JWST 41 Hubble Science Briefing 5/2/13
Thanks!! 42 Hubble Science Briefing 5/2/13