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 Hubble Science Briefing

The Solar system 8 planets in the Solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune Sizes to scale Distances NOT to scale Hubble Science Briefing 5/2/13 2

The first exoplanet: 51 Peg b (Mayor & Queloz 1995) 51 Peg b: Mass ≈ 0.5 Jupiter masses Orbital period = 4.2 days!! 51 Peg b: Mass ≈ 0.5 Jupiter masses Orbital period = 4.2 days!! A revolution!! Hubble Science Briefing 5/2/13 3

The radial velocity method How do we detect exoplanets? Indicates the mass of the planet credit Emmanuel Pécontal Hubble Science Briefing 5/2/13 4

The radial velocity method How do we detect exoplanets? Indicates the mass of the planet credit Emmanuel Pécontal Hubble Science Briefing 5/2/13 5

The radial velocity method How do we detect exoplanets? Indicates the mass of the planet credit Emmanuel Pécontal Hubble Science Briefing 5/2/13 6

The radial velocity method How do we detect exoplanets? Indicates the mass of the planet credit Emmanuel Pécontal Hubble Science Briefing 5/2/13 7

The radial velocity method How do we detect exoplanets? Indicates the mass of the planet credit Emmanuel Pécontal Hubble Science Briefing 5/2/13 8

The radial velocity method How do we detect exoplanets? Indicates the mass of the planet credit Emmanuel Pécontal Hubble Science Briefing 5/2/13 9

The transit method How do we detect exoplanets? Indicates the radius of the planet Hubble Science Briefing 5/2/13 10

The imaging method Direct detection of exoplanets How do we detect exoplanets? HR 8799 (Marois et al. 2008, 2010) Hubble Science Briefing 5/2/13 11

Historical background The discovery of exoplanets Hubble Science Briefing 5/2/13 12

1995: The first exoplanet around a Sun-like star, 51 Peg b Mayor & Queloz 1995 Historical background Hubble Science Briefing 5/2/13 13

1999: The first transiting exoplanet, HD b Charbonneau et al Historical background Hubble Science Briefing 5/2/13 14

2008: Direct imaging of Fomalhaut b and HR8799 b Marois et al Kalas et al Historical background Hubble Science Briefing 5/2/13 15

Léger et al : The first transiting super-Earth, CoRoT-7 b Historical background Hubble Science Briefing 5/2/13 16

2012: The first Earth-size exoplanets, Kepler 20 e & f Fressin et al Historical background Hubble Science Briefing 5/2/13 17

Historical background The discovery of exoplanets As of April 30 th, 2013: 880 exoplanets: 132 in multiple systems 308 transiting Hubble Science Briefing 5/2/13 18

And probably millions more… Historical background Hubble Science Briefing 5/2/13 19

Currently only a few exoplanets can be characterized Detection = Finding planets Characterization = Studying in detail individual planets, after their detection Requires a bright host star to maximize the signal Detection and characterization Basics Hubble Science Briefing 5/2/13 20

The power of the transit method Hubble Science Briefing 5/2/13 21

Transit spectroscopy with the Hubble Space Telescope Image of the target star on the detector Hubble Science Briefing 5/2/13 22 HST has several spectrographs on board

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 Hubble Science Briefing 5/2/13 23

First detection of an exoplanet atmosphere… HD209458b - HST STIS (Charbonneau et al. 2002) … that is escaping HD209458b - HST STIS (Vidal-Madjar et al. 2003, 2004) Transit spectroscopy with the Hubble Space Telescope Excess absorption Hubble Science Briefing 5/2/13 24

The NICMOS controversy Methane and water in the atmosphere of HD198733b (Swain et al. 2008) NICMOS: Near Infrared Camera and Multi-Object Spectrometer onboard Hubble Space Telescope Transit spectroscopy with the Hubble Space Telescope Hubble Science Briefing 5/2/13 25

A new look at NICMOS transmission spectroscopy of HD , GJ-436 and XO-1 “No conclusive evidence for molecular features” (Gibson et al. 2011) HD189733b Transit spectroscopy with the Hubble Space Telescope The NICMOS controversy Hubble Science Briefing 5/2/13 26

Need more observations Transit spectroscopy with the Hubble Space Telescope The NICMOS controversy Hubble Science Briefing 5/2/13 27

But NICMOS became unavailable… New instruments installed on HST, including Wide Field Camera 3 (WFC3) Installation by a team of astronauts in May, 2009 Transit spectroscopy with the Hubble Space Telescope Hubble Science Briefing 5/2/13 28

WFC3 observations of HD : coming this year… Transit spectroscopy with the Hubble Space Telescope Hubble Science Briefing 5/2/13 29

HD 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 Transit spectroscopy with the Hubble Space Telescope Sodium helps to understand the general characteristics of hot-Jupiters Hubble Science Briefing 5/2/13 30

HD b Recent observations with HST WFC3 (Deming et al. 2013) Detection of water vapor in the planet’s atmosphere! (signal: 200 parts per million) Best precision ever achieved for exoplanet spectroscopy (40 parts per million) Transit spectroscopy with the Hubble Space Telescope Hubble Science Briefing 5/2/13 31

HD b Transit spectroscopy with the Hubble Space Telescope Interpretation: Presence of clouds and/or haze in the planet’s atmosphere, that weaken the signal But water vapor signal is smaller than expected! Hubble Science Briefing 5/2/13 32

HD b Transit spectroscopy with the Hubble Space Telescope Interpretation: Presence of clouds and/or haze in the planet’s atmosphere, that weaken the signal But water vapor signal is smaller than expected! HST provides clues about HD b’s atmosphere: water vapor, with clouds and/or haze Hubble Science Briefing 5/2/13 33

GJ 1214 b A transiting super-Earth or mini-Neptune (Charbonneau et al. 2009) Radius = 2.7 R E Mass = 6.6 M E Density = 1.9 g/cm 3 (Earth: 5.5 g/cm 3 ) Marcy 2009 Transit spectroscopy with the Hubble Space Telescope Hubble Science Briefing 5/2/13 34

GJ 1214 b The spectrum is flat!! Bean et al Ground based observations Berta et al HST WFC3 Transit spectroscopy with the Hubble Space Telescope Hubble Science Briefing 5/2/13 35

GJ 1214 b Transit spectroscopy with the Hubble Space Telescope Atmosphere has to be “heavy” (high molecular weight)… Inconsistent with a cloud-free extended atmosphere But it might also be a very cloudy atmosphere Hubble Science Briefing 5/2/13 36

GJ 1214 b Atmosphere has to be “heavy” (high molecular weight)… But it might also be a very cloudy atmosphere Transit spectroscopy with the Hubble Space Telescope Inconsistent with a cloud-free extended atmosphere Still an open question… On-going HST program for more observations Hubble Science Briefing 5/2/13 37

The future Transiting Exoplanet Survey Satellite (TESS) NASA Mission for launch in 2017 Discover Transiting Earths and Super-Earths orbiting bright, nearby stars Principal Investigator: George Ricker (MIT) Aim: Hubble Science Briefing 5/2/13 38

The James Webb Space Telescope (JWST) 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 JWST… a big thing!! The future Hubble Science Briefing 5/2/13 39

Predicted performances: Example of carbon dioxide in a habitable SuperEarth The future The James Webb Space Telescope (JWST) Hubble Science Briefing 5/2/13 40

Conclusion These observations bring information about molecules, clouds, and haze in the atmosphere of exoplanets HST plays a major role in transit spectroscopy The transit method is the most powerful to characterize exoplanets The future: TESS and JWST Hubble Science Briefing 5/2/13 41

Thanks!! Hubble Science Briefing 5/2/13 42