Radial Velocity Prospects Current and Future A White Paper Report prepared by the Study Analysis Group 8 for the Exoplanet Program Analysis Group (ExoPAG) Contributing Authors: Peter Plavchan Missouri State University, Dave Latham Harvard-Smithsonian Center for Astrophysics, Radial Velocity Study Analysis Group co-chairs and ExoPAG Executive Committee members, Scott Gaudi Ohio State University, ExoPAG Executive Committee Chair, Justin Crepp Notre Dame, Dumusque Xavier Harvard-Smithsonian Center for Astrophysics, Gabor Furesz MIT, Andrew Vanderburg Harvard University, Cullen Blake University of Pennsylvania, Debra Fischer Yale University, Lisa Prato Lowell Observatory, Russel White Georgia State University, Valeri Makarov U.S. Naval Observatory, Geoff Marcy University of California, Berkeley, Karl Stapelfeldt NASA Goddard, Raphaëlle Haywood St Andrews University, Andrew Collier-Cameron St Andrews University, Andreas Quirrenbach University of Heidelberg, Suvrath Mahadevan Penn State University, Guillem Anglada Queen Mary, University of London, Philip Muirhead Boston University 1 1. Table of Contents 1. TABLE OF CONTENTS ..................................................................................................................................... 2 2. EXECUTIVE SUMMARY ................................................................................................................................... 4 3. NASA PROGRAMMATIC CONSIDERATIONS ............................................................................................. 7 3.1 KEPLER AND K2 .................................................................................................................................................................. 7 3.2 TESS AND JWST ................................................................................................................................................................ 9 3.3 FUTURE SPACE-BASED DIRECT IMAGING MISSIONS ...................................................................................................... 9 4 ANALYSIS: GROUND-BASED TELESCOPE RESOURCES NECESSARY TO MEET NASA OBJECTIVES ......................................................................................................................................................... 13 4.1 DEFINITION OF DOPPLER PRECISION .......................................................................................................................... 14 4.2 SURVEY SIMULATIONS .................................................................................................................................................... 14 4.2.1 TESS and Exo-C Target Samples ....................................................................................................................... 14 4.2.2 K Semi-amplitude Sensitivity .............................................................................................................................. 15 4.2.3 Choice of Telescope Aperture .............................................................................................................................. 15 4.2.4 Survey Simulation Parameters .......................................................................................................................... 16 4.2.5 Is a minimum of 10 observations per target realistic? ............................................................................ 19 4.2.6 Survey Simulation Results and Discussion .................................................................................................... 21 4.2.7 Summary Conclusions ............................................................................................................................................ 31 4.3 NIR AND/OR VISIBLE .................................................................................................................................................... 31 4.3.1. The spectral type and wavelength dependence of RV photon noise ................................................. 32 4.3.2. The spectral type and wavelength dependence of stellar jitter .......................................................... 36 4.3.3. Combining photon noise and stellar jitter as a function of spectral type and wavelength .... 40 4.3.4. Summary Conclusions ........................................................................................................................................... 45 4.4 SEEING OR DIFFRACTION LIMITED ............................................................................................................................... 46 5. EXOPLANET SCIENCE OBJECTIVES .......................................................................................................... 47 5.1 A SUMMARY OF THE HISTORICAL RELEVANCE OF PRVS TO THE EXOPLANET FIELD ........................................ 47 5.2 ASTROPHYSICAL CONSTRAINTS ON THE RADIAL VELOCITY METHOD .................................................................... 49 5.2.1 Stellar Activity Features and Time-Scales .................................................................................................... 50 5.2.2 Spectroscopic Properties of Stellar Jitter ...................................................................................................... 55 5.2.3 Wavelength Dependence ...................................................................................................................................... 55 5.2.4 Photometric Correlation ....................................................................................................................................... 56 5.2.5 Time-scale Dependence on Stellar Parameters .......................................................................................... 57 5.2.6 The Sun in Context ................................................................................................................................................... 58 5.3 RADIAL-VELOCITY SURVEYS IN THE RED AND NEAR-INFRARED ........................................................................... 59 5.4 YOUNG STARS, ACTIVE STARS ....................................................................................................................................... 62 6 INSTRUMENTATION OBJECTIVES ............................................................................................................ 65 6.1 CURRENT OR PLANNED SPECTROGRAPHS .................................................................................................................. 65 6.1.1 Visible Spectrometers ............................................................................................................................................. 66 6.1.2 Red/Near-Infrared Spectrographs ................................................................................................................... 68 2 6.2 WAVELENGTH CALIBRATION ........................................................................................................................................ 69 6.2.1 Common Optical Path ............................................................................................................................................ 69 6.2.2 Non-Common Optical Path .................................................................................................................................. 72 6.3 SPECTROGRAPH ILLUMINATION AND STABILIZATION .............................................................................................. 74 6.4 DIFFRACTION LIMITED PRV SPECTROGRAPHS ......................................................................................................... 83 7. U.S. COMMUNITY INPUT ............................................................................................................................. 88 7.1 NASA SCIENCE OBJECTIVES .......................................................................................................................................... 88 7.2 EXEP PROGRAM GOALS AND OBJECTIVES .................................................................................................................. 88 7.3 2010 DECADAL SURVEY ................................................................................................................................................ 88 7.4 NSF PORTFOLIO REVIEW .............................................................................................................................................. 89 7.6 2011 PENN STATE RV WORKSHOP ............................................................................................................................ 90 7.7 2008 EXOPLANET COMMUNITY REPORT RV CHAPTER .......................................................................................... 91 7.8 2008 EXOPLANET TASK FORCE REPORT ................................................................................................................... 92 8. ACRONYMS AND ACKNOWLEDGMENTS ................................................................................................ 94 9. REFERENCES ................................................................................................................................................... 96 3 2. Executive Summary In this white paper report, we present an assessment of the current capabilities and the future potential of the precise radial velocity (PRV) method to advance the NASA goal to “search for planetary bodies and Earth-like planets in orbit around other stars.” (U.S. National Space Policy, June