Sara Seager - Lecture1 - MIT

0 %
100 %
Information about Sara Seager - Lecture1 - MIT
Science

Published on September 23, 2014

Author: atner

Source: slideshare.net

Exoplanet Atmospheres: From Discovery to Characterization and Beyond Trent Schindler Trent Schindler Sara Seager Massachusetts Institute of Technology

Known Planets 1995 Based on data compiled by J. Schneider

Known Planets 1996 Based on data compiled by J. Schneider View slide

Known Planets 2000 Based on data compiled by J. Schneider View slide

Known Planets 2005 Based on data compiled by J. Schneider

Known Planets 2010 Based on data compiled by J. Schneider

Exoplanet Atmospheres Discovery Characterization Beyond

Transiting Planet Science Primary Eclipse Measure size of planet See star’s radiation transmitted through the planet atmosphere Secondary Eclipse See planet thermal radiation disappear and reappear Learn about atmospheric circulation from thermal phase curves 10-2 10-4 10-3

Courtesy Josh Winn See Seager and Mallen-Ornelas 2003

Identification of Atoms and Molecules H2O and CH4 in transmission from HST Swain et al. (2008) See also Grillmair et al. 2008. HD 189733b Na, H2O, CH4 , CO2, CO, hazes HD 209458b Na, H2O, CH4, CO, CO2, H Ly α

Day-Night Temperature Variation NASA/ESA/G. Bacon Spitzer Space Telescope

Day-Night Temperature Variation HD 189733 HD 189733b Knutson et al. 2007 HAT-P-7b Borucki et al. 2009

Thermal Phase Curves HD 189733 HD 189733b Knutson et al. 2007 Hottest regions are shifted away from the substellar point are interpreted as advection by a prograde superrotating equatorial jet. No model yet explains or predicts the westward-shifted cold spot

Variability Madhusudhan and Seager, 2009 Data from: Swain et al. 2008, Charbonneau et al. 2008, Grillmair et al. 2008

Variability: CO2 10-18 10-21 10-21 10-21 10-18 From VPL website

A Comment on Data Courtesy F. Pont Transit Radius (Rp/R*) 8 0.6 1 2 5 Wavelength (μm) Data from Pont et al. 2008, Swain et al. 2008 Tinetti et al. 2007, Beaulieu et al. 2008, 2009, Desert et al. 2009. Figure courtesy Pont. Disagreement in the literature in Spitzer data is gradually being resolved over time, due to understanding different approaches to systematics’ removal.

Summary of Atmosphere Highlights Identification of molecules Day-night temperature gradients Variability at 2-σ level Atmospheric escape Hot Jupiters are dark There is real data on exoplanet atmospheres. It may be limited, but many people are modeling the data

Exoplanet Atmospheres Discovery Characterization Highlights Model Constraints Beyond

Exoplanet Atmosphere Models Get a recipe + Fit the data Vary ingredients = Everything other than g and F* Exoplanet atmosphere modeling is like cooking – S. Aigrain

Exoplanet Atmosphere Models Charbonneau et al. 2008 Swain et al. 2008 Grillmair et al. 2008 Previously unanswered questions • What is the “best-fit” model? • How is the best-fit quantified? • Is the “best-fit” model unique? • If the best-fit is not unique, what are the allowed ranges of model parameters?

Hot Jupiter Radiative Transfer 1D, plane parallel, LTE Boundary Conditions • Stellar irradiation • Intrinsic energy source Chemical Equilibrium ∞ ∫ dλ = 0 dT dz Model Free Parameters • Day-night redistribution: • Unknown opacity: • Composition ( ) + clouds, etc. Caveats • No longer “self consistent” models • Computation time and convergence • Just a few models are run € dIλ dτ λ = Iλ − Sλ κλ Jλ − Sλ ( ) 0 = − γ −1 γ μg kB dP dz = −ρg P = ρkBT μ

A Temperature and Abundance Retrieval Technique Run millions of models to constrain T and abundances Madhusudhan and Seager, 2009 N. Madhusudhan PhD 2009

Atmosphere Temperature Profiles

HD 189733 Madhusudhan and Seager 2009 Grillmair et al. 2008 Charbonneau et al. 2008 Deming et al. 2006 Swain et al. 2008

Result #1 Variability Variability: True uncertainty in the data? Then no useful limits on molecular abundances Or the atmospheres are variable both in the energy redistribution state and in the concentrations of molecular abundances Madhusudhan and Seager 2009

Result #2 Quantitative Abundances Spitzer/IRAC HD 189733 b Madhusudhuan and Seager 2009

Result #2 Quantitative Abundances Spitzer/IRAC + HST/NICMOS HD 189733 b Madhusudhuan and Seager 2009

Result #3 Challenge to Thermal Inversion Evidence for thermal inversion difficult to assess for most exoplanets, assuming 2 σ data uncertainties and/or a range of molecular abundances Madhusudhan and Seager, submitted to ApJ

Result #4 Lack of CH4 on the Hot Neptune GJ 436b Stevenson et al. Nature 2010 Madhusudhan and Seager, submitted to ApJ

Atmosphere Summary We have moved beyond discovery to characterization  several robust observational highlights  a quantitative tool for atmospheres

Exoplanet Atmospheres Discovery Characterization Beyond

Ground-Based Advances de Mooij & Snellen 2009 • Very Hot Jupiter secondary eclipses • Directly imaged Jupiters • Search for transiting super Earths

β Pictoris: New Planet A composite image of the planet from 2003 and 2009 and the disk. Lagrange et al., Science 2010 (today)

The M Star Opportunity Semi-Major Axis Sun K2 M6 Probability = 1/200 P = 365 days Transit depth = 10-4 Probability = 1/140 P = 177 days Transit depth = 1.25 x10-4 Probability = 1/50 P = 13 days Transit depth = 0.001 Tidally-locked

John E. Kauffman used with permission

Atmospheric escape Photochemistry Radiative transfer Atmospheric Composition Chemical equilibrium/disequilibrium Atmospheric circulation Clouds Connection with observations

JWST = TPF? Lecture #3 Wed. June 23

Earth’s Spectrum Turnbull et al. 2007 Pearl and Christensen 1997 Lecture #3 Wed. June 23

Summary • Discovery – Hundreds of exoplanets are known – Atmosphere measurements for over dozens • Characterization – A few robust observational highlights show that exoplanet atmospheres are being studied in detail – Models are required to solidify interpretation • Beyond – Direct imaging of hot young planets – The M star opportunity: searching for super Earths orbiting close to low-mass stars and planned characteriztiaon with JWST

Seager & Deming, Annual Reviews of Astronomy and Astrophysics, 09/2010 Madhusudhan and Seager ApJ, 2009 Seager, “Exoplanet Atmospheres: Physical Processes” 2010, Princeton University Press Trent Schindler Trent Schindler References

Add a comment

Related presentations

How organisms adapt and survive in different environment.

Aplicación de ANOVA de una vía, modelo efectos fijos, en el problema de una empres...

Teori pemetaan

Teori pemetaan

November 10, 2014

learning how to mapping

Libros: Dra. Elisa Bertha Velázquez Rodríguez

Materi pelatihan gis

Materi pelatihan gis

November 10, 2014

learning GIS

In this talk we describe how the Fourth Paradigm for Data-Intensive Research is pr...

Related pages

Big Ideas (Video) - TVO

TVO Big Ideas presents Sara Seager of the Massachusetts Institute of Technology discussing Exoplanets and the Search for Habitable Worlds Big Ideas ...
Read more

Big Ideas (Audio) - TVO

TVO Big Ideas presents Sara Seager of the Massachusetts Institute of Technology discussing Exoplanets and the Search for Habitable Worlds Big Ideas ...
Read more

Warming Slowdown? (Part 1) | Azimuth

... L. Long, A. Mariotti, J. Meyerson, K. Mo, D. Neelin, Z. Pan, R. Seager ... […] 2014/05/29: JCBaez: Warming Slowdown? (Part 1 ... Sarah G ...
Read more

c Many historians argue that Claudius' biggest fault was ...

c Many historians argue that Claudius' biggest fault was that he was a bit of a weak-willed man and from HIST 121 at American Public University
Read more