Astro2020 Exoplanet White Papers
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Link to white paper/draft
Community Endorsement of the National Academies “Exoplanet Science Strategy” and “Astrobiology Strategy for the Search for Life in the Universe” ReportsPeter Plavchanpplavcha@gmu.eduPlease contact Peter Plavchan to have your name added to this white paper; or go to and fill out the form.YesYes, as many as possibleThe National Academies “Exoplanet Science Strategy” (ESS) and “Astrobiology Strategy for the Search for Life in the Universe” (ABS) reports present timely and consensus assessments of the current status, priorities and recommendations of the exoplanet and astrobiology science communities. We are signing our support for the findings and recommendations contained in the ESS and ABS as representing our consensus input to the Astrophysics 2020 decadal survey.Exoplanet Science Strategy and Astrobiology Strategy reports
Remote Occulter For the 2030's (starshade with ground-based telescope)John C Matherjohn.c.mather@nasa.govEliad Peretz + ~20 others. Please contact or to participateYesYesAn orbiting starshade coordinated with a 30-m class ground telescope with adaptive optics opens new areas of exoplanet science, with greater angular resolution than any planned space telescope. As observing speed scales as D^4, an exposure time of a minute gives an image of an entire planetary system at 10 pc, and an exposure of a few hours gives spectroscopy. The white paper will quantify what could be done scientifically and what engineering requirements would have to be met.
Starshade, Exoplanets, Direct Imaging, Spectroscopy
A Strategy for Understanding Planet FormationAlycia Weinbergeraweinberger@carnegiescience.eduKarl StapelfeldtYesThe exoplanet science strategy reference above does deal with planet formation, but it is not a strategy for understanding planet formation. I intend to expand upon Chapter 4.10 of that report to lay such a strategy.Planet Formation
The WFIRST Exoplanet Microlensing SurveyDavid Bennett
A Statistical Comparative Planetology Approach to Maximize the Scientific Return of Future Direct Imaging MissionsJade Checlairjadecheclair@uchicago.eduRobert Webber, Y. Katherina Feng, Chris Stark, Jacob Bean, Tyler Robinson, Eliza Kempton, Dorian Abbot, Ravi Kopparapu, Daniel Apai, Gioia Rau, Shawn Domagal-GoldmanYesYesProvided that sufficient resources are deployed, we can look forward to an extraordinary future in which we will characterize potentially habitable planets. Until now, we have had to base interpretations of observations on habitability hypotheses that have remained untested. To test these theories observationally, we propose a statistical comparative planetology approach to questions of planetary habitability. The key objective of this approach will be to make quick and cheap measurements of critical planetary characteristics on a large sample of exoplanets, exploiting statistical marginalization to answer broad habitability questions. This relaxes the requirement of obtaining multiple types of data for a given planet, as it allows us to test a given hypothesis from only one type of measurement using the power of an ensemble. This approach contrasts with a “systems science” approach, where a few planets would be extensively studied with many types of measurements. A systems science approach is associated with a number of difficulties which may limit overall scientific return, including: the limited spectral coverage and noise of instruments, the diversity of exoplanets, and the extensive list of potential false negatives and false positives. A statistical approach could also be complementary to a systems science framework by providing context to interpret extensive measurements on planets of particular interest. We strongly recommend future missions with a focus on exoplanet characterization, and with the capability to study large numbers of planets in a homogenous way, rather than exclusively small, intense studies directed at a small sample of planets.exoplanets, astrobiology, LUVOIR, HabEx
The Exoplanet Yield Landscape for Future Direct Imaging MissionsChris Starkcstark@stsci.eduRus Belikov, Matthew R. Bolcar, Brendan P. Crill, Tyler Groff, Brian A. Hicks, John Krist, Johan Mazoyer, Bijan Nemati, Laurent Pueyo, Bernard J. Rauscher, A. J. Riggs, Garreth Ruane, Dan Sirbu, Remi Soummer, Kathryn St. Laurent, Neil Zimmerman, Ravi Kopparapu, Rhonda Morgan, Gioia Rau, Michael McElwainYesYes
Frameworks and Targets for Exoplanet Biosignature Detection and Science (might be 2 papers)Tom Greenetom.greene@nasa.govYes: Especially encourage JWST GTOsYes: especially encourage JWST ERS and potential JWST GOsTBR: Using the GTO program as an example, we highlight how early JWST observations will advance understanding of exoplanet atmospheres. This will likely include significant insights into the compositions, chemistry, clouds, and thermal profiles of warm-to-hot gas-dominated planets. These will in turn inform our understanding of atmospheric property correlations and extrasolar planet formation. Some insight will likely be gained into rocky planet atmospheres as well. This paper is intended to set the scientific context for what will likely be learned about exoplanet atmospheres in the early 2020s so that Astro2020 can make informed decisions about future exoplanet science advances and the needed projects / missions.Planetary SystemsJWST, exoplanet atmosphere characterization
Exoplanet Biosignature Summary (from 2018 Astrobiology special issue on Exoplanet Biosignatures may be 2 papers)
Edward Schwieterman, EBWWW authorseschwiet@ucr.eduBiosignature review, Agnostic biosignatures, novel biosignaturesThis will summarize the salient conclusions and recommendations from the Exoplanet Biosignatures Workshop Without Walls, providing clear tables and figures on the suite of observations to target for biosignatures, directions for novel biosignatures, and most likely a second white paper devoted to frameworks to interpret observations.exoplanets, biosignatures, astrobiology, Bayesian
Venus as a Nearby Exoplanet LaboratoryStephen Kaneskane@ucr.eduGiada Arney, David Crisp, Shawn Domagal-Goldman, Lori S. Glaze, Colin Goldblatt, David Grinspoon, James W. Head, Adrian Lenardic, Cayman Unterborn, Michael J. Way, Ravi Kopparapu, Wladimir Lyra, Noam IzenbergYesYesThe goals of the astrobiology community are focussed on developing a framework for the detection of biosignatures, or evidence thereof, on objects inside and outside of our solar system. A fundamental aspect of understanding the limits of habitable environments and detectable signatures is the study of where the boundaries of such environments can occur. Thus, the need to study the creation, evolution, and frequency of hostile environments for habitability is an integral part of the astrobiology story. These provide the opportunity to understand the bifurcation between habitable and uninhabitable. The archetype of such a planet is the Earth’s sister planet, Venus, and provides a unique opportunity to explore the processes that created a completely uninhabitable environment and thus define the conditions that can rule out bio-related signatures. We advocate a continued comprehensive study of our sister planet, including models of early atmospheres, compositional abundances, and Venus-analog frequency analysis from current and future exoplanet data. Moreover, new missions to Venus that provide in-situ data are necessary.Planetary Habitabilityexoplanets, habitability, Venus
A procedure for observing rocky exoplanets to maximize the likelihood that atmospheric oxygen will be a biosignature (previously submitted to NAS)Steve Deschsteve.desch@asu.eduStephen Kane, Carey Lisse, Cayman Unterborn, Hilairy Hartnett, Dan Shim?yes?Basically, oxygen is not a biosignature if a planet has too much water. So, counterintuitively, we want to look for planets with very *little* waterDetecting life on exoplanetsexoplanets, life detection
Imaging and weighing the Gaia planets with direct imaging and radial velocity, additional yields and targets for high-contrast imaging from a full-sky astrometric WFIRST snapshotTim will give a huge, free planet haul: we can get masses and have targeted imaging campaigns. How do we make the best use of these free data, and can we make the scientific power that much greater with a full-sky shallow WFIRST survey?TMT, GMT, WFIRST
Constraining Stellar Photospheres as an Essential Step for Transmission Spectroscopy of Small ExoplanetsBen Rackhambrackham@as.arizona.eduDaniel Angerhausen, Daniel Apai, Ludmila Carone, Heather Cegla, Julien de Wit, Shawn Domagal-Goldman, Nestor Espinoza, Michael Gully-Santiago, Raphaelle Haywood, Renyu Hu, Andres Jordan, Laura Kreidberg, Joe Llama, Mercedes Lopez-Morales, Johanna Teske, Gioia Rau, Carey Lisse

Please contact Ben Rackham to participate.
YesYesTransmission spectroscopy during planetary transits is expected to be a major source of information on the atmospheres of small (approximately Earth-sized) exoplanets in the next two decades. This technique, however, is intrinsically affected by stellar spectral features introduced by the heterogeneity of stellar photo- and chromospheres. Such stellar signals will often reach or exceed the scale of planetary spectral features. Finding effective methods to disentangle stellar and planetary features—or at least to quantify the possible scales of stellar features–for the most important exoplanets is a necessary step for deepening our understanding of exoplanet atmospheres through high-precision transmission spectra. This will require expanding our understanding of stellar heterogeneity, which is currently limited by the available data, and refining techniques for jointly constraining stellar and planetary signals in transmission spectra.Planetary Systemsexoplanets, transmission spectroscopy, stellar activity
14 ManyYesYesThe search for technosignatures (i.e. SETI) has many overlaps with the search for biosignatures and other areas of astrobiology and astronomy. This effort is being organized on its own spreadshet, at the URL to the right. We seek cosigners, co-authors, and reciprocal language in related white papers. Specifically: authors of other white papers can cite and point to searches for technosignatures as part of their science case, and technosignatures white papers can likewise point to exoplanet/astrobiology white papers as supporting theirs.Technosignaturesastrobiology, biosignatures, atmospheric characterization
Characterizing Exoplanets for HabitabilityTyler Robinson, Jacob Lustig-Yaegertyler.robinson@nau.eduY. Feng, Kim Bott, Karan Molaverdikhani, Nicolas IroSureYesHabitability, Remote Sensingexoplanets, habitability, characterization, oceans, atmosphere, terrestrial
A proposed partial solution to the "Postdoc Crisis"Peter Openly compete the national prize postdoc host institutions (e.g. faculty apply) to better align the host institutions with the institutions that have faculty hires. Take advantage of the democratization of research from archival data and national open-access facilities. Use the medical profession residency program as a model of postdoc fellow and host institution matching. Prize committee to consist of faculty from institutions that will get a commitment from their institution to make a faculty hire in 3 years time, with preference given to the prize fellow (e.g. offer to fellow, fellow has right to decline and search elsewhere). This brings the host institution selection process "out of the dark". Under the status quo, prospective fellows must select top institutions as their host organization to maximize their chances of success of winning the fellowship. This results in an imbalance between where postdocs tend to work at institutions that have disproportionally fewer faculty hires (e.g. number of postdocs at a given top institution >> number of faculty hires made at that institution, forcing many postdocs to leave and move). Conversely, under the status quo, the typical institution making a faculty hire has many fewer postdocs (0 to a few). By aligning the prize fellow host institutions with the institutions making the faculty hires, we reduce the number of times postdocs have to move and set a national example. Top institutions are also already likely to have their own institutional prize fellowships, and support multiple postdoctoral positions on grant funding, already in excess of the faculty hires that will be made at the top institutions.State of the Professionpostdoc
Value of Directly Imaging Giant Planets in Reflected LightMark Marleymark.s.marley@nasa.govNikole Lewis, Natasha Batalha YesYesA look at both the intrinsic science value of giants (comparative atmospheres, composition, system architectures, etc.) as well as the value of giants as pathfinders for validating methods of intrepetting reflected light datasets before (or in tandem with) the application of these methods to potentially habitable terrestrial planets.
Key Technology Challenges for the Study of Exoplanets and the Search for Habitable Worlds
Brendan Crillbcrill@jpl.nasa.govNick Siegler, Shawn Domagal-Goldman, Eric Mamajek, Karl Stapelfeldt, Rhonda Morganthis is going to be an update of the whitepaper we submitted to the ESS, reflecting advances in the past year. technology
Benefits of synergistic observations of habitable planet candidates for future flagship missionsCourtney Dressingdressing@berkeley.edudiscussions of the benefits of observing candidate habitable planets using a variety of methods and facilitiesPlanetary Systems
exoplanets, astrobiology, LUVOIR, HabEx, ELTs, JWST, RV, ground-based surveys
The remote detectability of Earth's biosphere through time and importance of UV imaging capability for characterizing habitable exoplanetsChris Reinhard, Edward, eschwiet@ucr.eduStephanie OlsonYesBenefits of planet imaging in UV (O3 sensitivity) for LUVOIR/HabEx and 3.5-5um sensitivity for OST (CO, CO2, et.). Partial resubmission of NAS paper. HZ planet characterizationexoplanets, astrobiology, LUVOIR, HabEx, OST
The value of astrometry for exoplanet scienceEduardo Bendekeduardo.a.bendek@nasa.govOlivier Guyon, Mike Shao, Gautam Vashist, Mark Marley, Peter Tuthill, Slava Turyshev, Bertrand MennessonYesYesExoplanets mass measurements will be a critical next step to assess the habitability of Earth-like planets: a key aspect of the 2020 vision in the previous decadal survey and also central to NASA's strategic priorities. Precision astrometry delivers measurement of exoplanet masses, allowing discrimination of rocky planets from water worlds and enabling much better modeling of their atmosphere improving species retrieval from spectroscopy. The scientific potential of astrometry will be enormous. The intrinsic astrophysical noise floor set by star spots and stellar surface activity is about a factor of ten more benign for astrometry than for the more established technique of Radial Velocity, widening the discovery region and pushing detection thresholds to lower masses than previously possible. On the instrumental side, precision astrometry is limited by optical field distortion and detector calibration issues. Both technical challenges are now being addressed successfully in the laboratory. However, we have identified the need to continue these technology development efforts to achieve sub-microarcsecond astrometry precision necessary for detection and characterization of Earth-like planets around nearby FGK stars. The international community has realized the importance of astrometry, and various astrometry missions have been proposed and under development, with a few high profile missions now operational. Exoplanet detection and characterizationexoplanets, measure masses, habitable planets, sun-like stars
The Demographics and Atmospheres of Giant Planets with the ELTsBrendan Bowler, Steph Sallum,
Magnetic Fields of Extrasolar Planets: Planetary Interiors and HabitabilityJoseph LazioJoseph.Lazio@jpl.nasa.govLazio, Hallinan, + 15 othersYesYesJupiter’s radio emission has been linked to its planetary-scale magnetic field, and spacecraft investigations have revealed that most planets, and some moons, have or had a global magnetic field. Generated by internal dynamos, magnetic fields are one of the few remote sensing means of constraining the properties of planetary interiors. For the Earth, its magnetic field has been speculated to be partially responsible for its habitability, and knowledge of an extrasolar planet’s magnetic field may be necessary to assess its habitability. The radio emission from Jupiter and other solar system planets is produced by an electron cyclotron maser, and detections of extrasolar planetary electron cyclotron masers will enable measurements of extrasolar planetary magnetic fields.Planetary Systemsmagnetic fields, habitability, planetary interiors
Detecting and Characterizing Small Planets Around Stars Across Spectral TypesJi Wang, Michael, YesYesExoplanets
Watching Planets Form with the ELTsSean Brittain, Hannah Jang-Condell, Michael Liu, Alycia,,,
Jaehan Bae, Alan Boss, Thayne Currie, Sarah Doson-Robinson, Jacqueline Faherty, Eric Gaidos, Peregrine McGehee, Michael Meyer, Colette Salyk, Gioia RauYesYesA proposed key science program for the US ELT effort to establish the chemical conditions, locations & timescales for planet formation via (1) high-resolution infrared spectroscopy to measure the physical and chemical conditions in protoplanetary disks, (2) study planet-disk interactions through imaging & spectro-astrometry, and (3) directly detect & characterize protoplanets and their circumplanetary disks.Disks & protoplanets
Durable Community Support for Exoplanet Catalogs and ArchivesJoshua Pepperjoshua.pepper@lehigh.eduYesYesThe ability to investigate exoplanet populations and demographics depends on reliable, accessible, and curated archives of all known exoplanets and their respective parameters. To date, much of that work has been handled by the NASA Exoplanet Archive. It is essential to maintain this resource as both a repository of information and connective hub for population studies over the next decade, and to explore whether supplemental archives or other resources are needed.Policies and Community Resourcesarchives, demographics, population studies
This draft is view-only for now, but contact me if you would like editing permission
Exoplanet Catalogs that Support Demographic StudiesSteve Brysonsteve.bryson@nasa.govYesYesExoplanet demographics is critical for exoplanet observation program and mission design. As various exoplanet surveys, including RV, transit, microlensing, atmospheric spectra, and direction detection, produce catalogs, they should provide sufficient information and analysis for comparison with other catalogs. This includes characterization of catalog completeness and reliability, which brings up issues of uniform methods of catalog creation. This white paper will survey previous catalogs and their efforts to address these issues, and lay out principles that facilitate demographics based on multiple catalogs, complementing and supporting the demographics section of the ESS report.Demographicsdemographics, population studies
Future Research Directions for Exoplanet BiosignaturesShawn Domagal-Goldmanshawn.goldman@nasa.govYesYesThis is a re-submission of the exoplanet biosignatures review paper that we submitted to the NAS Exoplanet White Paper call. The main differences this time around will be a slightly broader introduction, and a longer section on future research needs. That section was ~1 paragraph long last time and we want it to be ~1 page long (or at least half a page) this time.
Astrobiology as a Observation-Driven ScienceShawn Domagal-Goldmanshawn.goldman@nasa.govKim BottYesYesThis white paper will call for era of astrobiology missions both in and beyond Astrophysics observatories. And it will discuss how Astrobiology is a discipline with testable hypotheses that require space-based observation to falsify or confirm. The goal would be to map much of the astrobiology strategy document to specific missions/observations. So this would include and make mention of the searches for global habitability and biosignatures on such worlds… but it would also go beyond that, and mention the need for observations of solar system planets (both remote and in situ) and observations of the formation and evolution of planetary systems. Astrobiology, biosignatures, exoplanets, origins of stars, habitability, origins
Observations of Exoplanet ExospheresEric Lopezeric.d.lopez@nasa.govDrake Demingyesyes
General overview of host star characterizationNatalie Hinkelnatalie.hinkel@gmail.comPatrick Young, Vlad Airapetian, Allison YoungbloodYesYesThis white paper will briefly address the wide variety of stellar sub-fields needed to understand holistic planetary habitability, for example: abundances (detailed abundances for FGKM-stars), ages (through whatever methods), activity and magnetic fields, etc. Short sub-sections are welcome to cover these and other necessary fields of study, where each sub-section includes a brief overview of the current state-of-the-field, impact on exoplanets, and future required observations/models/instrumentation. Ideally, each sub-subsection could be presented as an autonomous white paper -- but we thought it was a good idea to have one paper that summarizes required topics of stellar characterization.
Host Starstar, stellar characterization, exoplanets, habitability
Stellar abundances and planetary compositionNatalie Hinkelnatalie.hinkel@gmail.comPatrick Young, Gioia RauYesYesA more expansive view (per the above white paper) of how stellar abundances give insight into planetary interior structure and mineralogy, especially in light of the lack of direct surface measurements.Host Starstar, stellar abundances, planetary composition, planetary mineralogy
A Search for Earth-like Bio-signatures in Rocky Planets around Nearby Stars with the ELTsMercedes Lopez-Moralesmlopez-morales@cfa.harvard.eduThayne Currie, Johanna Teske, Eric Gaidos, Eliza Kempton, Jared Males, Nikole Lewis, Sagi Ben-Ami, David Charbonneau, Laird Close, Mark Dickinson, Courtney Dressing, Cynthia Froning, Quinn Konopacky, Dimitri MawetC, Deno Stelter, Andrew Szentgyorgyi, Ji WangYesYesCombined observations with the GMT and the TMT can study the atmospheres of rocky planets in the habitable zone of stars close to the Sun. The aim of this white paper is to highlight the potential of ground-based observing programs with ELTs to detect molecules that are present in our own Earth's atmosphere, i.e. molecular oxygen, water, methane, ozone, and carbon dioxide, and which in combination are thought to represent a signature of biological activity on the surface of an Earth-like planet. The scientific goal is to answer three key questions: What are the atmospheric characteristics of rocky planets in the habitable zone of nearby stars? How common are those molecules in those planets? How similar or dissimilar are those planets to Earth? Such a program would use transmission spectroscopy, reflected-light direct imaging, thermal infrared direct imaging observations to obtain spectra/narrowband photometry of candidate Earth-like planets previously identified from transit, radial-velocity, and/or astrometric observations. Those molecules can be detected in the planets' atmospheres using observations of transmitted or reflected light at wavelengths shorter than 3.5 microns and by observations of thermal emission at longer wavelengths. Planned and/or proposed instruments on GMT and TMT will enable this science, and the combined effort of these observatories will be critical to its success. Finally, such program will complement and thus enhance the scientific return of future NASA missions to characterize the habitability of nearby rocky planets.HZ planet characterizationexoplanets, habitability, biosignatures, transmission spectroscopy, direct imaging
Using Ground-based Telescopes to Mature Key Technologies and Advance Science for Future NASA Exoplanent Direct Imaging MissionsThayne Curiecurrie@naoj.orgRuslan Belikov, Olivier Guyon, Christian Marois, Mark Marley, Kerri Cahoy, Michael McElwain, Eduardo Bendek, Marc Kuchner, Michael Meyernot surepossiblyGround-based telescopes have been playing a leading role in exoplanet direct imaging science and technological development for the past two decades and will continue to have an indispensable role for the next decade and beyond. Extreme adaptive optics (AO) systems will advance focal-plane wavefront control and coronagraphy, augmenting the performance of and mitigating risk for WFIRST-CGI, while validating performance requirements and motivating improvements to atmosphere models needed to unambiguously characterize solar system-analogues with HabEx/LUVOIR. Specialized instruments for Extremely Large Telescopes may deliver the first thermal infrared images of rocky planets around Sun-like stars, providing HabEx/LUVOIR with numerous exo-Earth candidates and key ancillary information that can help clarify whether the planets are habitable. direct imaging tech developmentexoplanets, direct imaging, coronagraphy, wavefront control
Dust in the interplanetary region of mature stars (including exozodi): a key observable to infer planetary systems current dynamical state and formation historyBertrand Mennessonbertrand.mennesson@jpl.nasa.govJeremy Kasdin, Bruce Macintosh, John Debes, Chris Stark, Steve Ertel, Phil Hinz, Vanessa Bailey, Karl Stapelfedlt, Dimitri Mawet, Nicholas Scott, Aki Roberge, Carey Lisseyesyes
Cold Debris Disks as Strategic Targets for the 2020sJohn Debesdebes@stsci.eduChris Starkyesyesexoplanets, debris disks, planetary systems
Direct imaging of exoplanets in nearby multi-star systemsRuslan Belikovruslan.belikov-1@nasa.govDan Sirbu, Eduardo Bendekyesyes
Atmospheric disequilibrium as an exoplanet biosignature: Opportunities for next generation telescopesJoshua Krissansen-Tottonjoshkt@uw.eduDavid Catlingyesyes
Reconstructing Extreme Space Weather From Planet Hosting Stars Vladimir Airapetianvladimir.airapetian@nasa.govV. Adibekyan (UPORTO), M. Ansdell (University of Hawaii), D. Alexander (Rice University), T. Barkley (NASA GSFC), T. Bastian (NRAO), S. Boro Saikia (University of Vienna), O. Cohen (University of Massachusetts Lowell), M. Cuntz (UFZ), W. Danchi (GSFC/SEEC), J. Davenport (UWA), J. DeNolfo (NASA GSFC), M. De Rosa (LMRC), R. DeVore (NASA GSFC), C. F. Dong (Princeton University), J. J. Drake (Harvard-CfA), K. France (CU Boulder), K. Herbst (University of Kiel), K. Garcia-Sage (GSFC/SEEC/CUA), A. Glocer (GSFC/SEEC), J. L. Grenfell (German Aerospace Center), G. Gronoff (NASA LaRC/SSAI), N. Gopalswamy (NASA/GSFC), M. Guedel (University of Vienna), H. Hartnett (Arizona State University), N. R. Hinkel (Arizona State University), A. G. Jensen (UNK), M. Jin (LMSAL), C. Johnstone (University of Vienna), P. Kalas (UC Berkeley), S. Kahler (? AFB), S. R. Kane (UC Riverside), C. Kay (NASA GSFC)/SEEC), J. Lazio (?), J. Leake (GSFC), G. Li (University of Alabama), T. Lueftinger (University of Vienna), B. Lynch (UC Berkeley), W. Lyra (Max Planck Institute for Astronomy), A. M. Mandell (GSFC/SEEC), K. E. Mandt ( Johns Hopkins University APL), H. Maehara, W. B. Moore (Hampton University and National Institute of Aerospace), Mouchou (CfA), Y. Notsu (Kyoto University), L. D. Oman (GSFC/SEEC), R. A. Osten (STScI, JHU), R. Oran (MIT), R. Petre (NASA GSFC), R. M. Ramirez (ELSI), S. Rugheimer (University of St Andrews), J. E. Schlieder (GSFC/SEEC), Shkolnik (University of Arizona), K. Shibata (Kyoto University), J. D. Schnittman (NASA GSFC), David Soderblom (STScI), Igor Sokolov (University of Michigan), A. Usmanov (University of Delaware), Van Der Holst (University of Michigan), A. Vidotto (University of Dublin), A. Vourlidas (JHU), S. Wolk (CfA), G. P. Zank (University of Alabama)With over 4000 exoplanets detected by Kepler and other ground-based and space missions, the young field of exoplanetary science is witnessing the era of renaissance as the detection of exoplanetary systems moves to the phase of their physical characterization. As these missions provide an emerging picture of formation and evolution of exoplanetary systems, the search of habitable worlds becomes one of the fundamental questions to explore. To tackle such a complex problem, we need to specify the conditions favorable for origin, development and sustaining life as we know it. This requires the understanding of global (astrospheric) and local (atmospheric, surface and internal) environments of exoplanets in the framework of the physical processes of interaction between evolving planet hosting K-M dwarf stars with exoplanets along with exoplanetary evolution over geological timescales, and resulted impact on climate and habitability of exoplanets. The complex of astrophysical, physico-chemical atmospheric and geological processes can only be understood through interdisciplinary studies with incorporation of progress in heliophysics, astrophysics, planetary, Earth sciences and origin of life community. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo)planets may significantly modify the current definition of the habitable zone and provide new directions for searching for signatures of life. Thus, characterization of stellar outputs in the space between the planet host star and exoplanets becomes an important task for further understanding their effects on habitability.
Advancing Exoplanet Science Requires NASA Support for Coordination between the Astrophysics and Planetary CommunitiesKathleen Mandtkathleen.mandt@jhuapl.eduPlease contact Kathy Mandt to be added to this white paper, which is available on google docs at the link in the title columnYesYes
The Importance of the Thermal Infrared for Characterizing Terrestrial PlanetsMike Linemrline@asu.eduJ. Fortney, T. Greene, T. Kataria, K. Stevenson, L. Tremblay, R. Zellem, E. Schwieterman, B. Mennesson, N. Iro, C. MorleyYesYesThe primary objective of this white paper is to illustrate the importance of the thermal infrared in characterizing terrestrial planets. We will review the importance of "mid-IR" emission observations for understanding global energy balance and climate of terrestrial worlds. We will then highlight the role that emission observations have played in characterizing EGP's over the past ~10 years. Finally, we will discuss the key pieces of information contained within mid-IR thermal emission observations, like molecular absorption and thermal structure (1- and 2-D).
Exploring the Atmospheres of Irradiated Exoplanets at High Spectral ResolutionDiana Dragomir, Eliza Bean, I. Crossfield, E. Gaidos, N. Lewis, M. Line, R. Lupu, G. ZhousureYesThe best-characterized exoplanets to date are planets on close-in transiting orbits around their host stars. The high level of irradiation and transiting geometry of these objects make them ideal targets for atmospheric investigations. However, the modest apertures of many current telescopes allow mostly low resolution spectra to be observed for transiting planets, failing to extract key physical and chemical properties of their atmospheres. The future 30-meter class telescopes will set the stage for a substantial leap in our understanding of exoplanet atmospheres. We propose a two-pronged survey to gain unprecedented insight into the atmospheres of close-in exoplanets via observations with the ELTs. (1) We will measure global-scale atmospheric circulation and planetary rotation for a sample of 40 hot Jupiters to glean insight into the unique radiative forcing regime governing highly-irradiated, tidally-locked giant planets. (2) We will extract atmospheric composition and abundance ratio information for $>50$ sub-Neptunes and super-Earths (including candidate disintegrating planets) to constrain their formation and evolution histories. Each of these efforts is made possible by the unparalleled combination of high spectral resolution instrumentation and large aperture size of the ELTs. This survey will enable the first statistical study of atmospheric circulation in extrasolar giant planets, and will provide detections of trace gases and measurements of atmospheric escape in small-planet atmospheres, far exceeding the reach of JWST.Planetary SystemsTMT, GMT, exoplanet atmosphere characterization
Using Obliquities and Masses to Probe Exoplanet ArchitecturesGeorge Zhou, Marshall Johnson, Dave Ciardigeorge.zhou@cfa.harvard.eduA. Vanderburg, E. Gaidos YesYesThe orbital obliquities of exoplanets--i.e., the relative orientation between the planetary orbit and the stellar rotation--is a key tracer of how planets form and migrate. The planetary orbits in our own solar system are nearly aligned with the Sun's rotation, but many hot Jupiters have highly misaligned or even retrograde orbits. The orbital obliquities for smaller planets are almost totally unexplored as their small transit depths make such observations very challenging. The ELTs are capable of measuring the orbital obliquities of super-Earths and mini-Neptunes at a wide range of orbital periods and stellar types; only with the ELTs will we be able to access the population of small planets that are the most common outcome of planet formation. This can be accomplished with time-series high-resolution spectroscopy through the planetary transit, and detection of the perturbation to the rotationally broadened line profile due to the planet with either Doppler tomographic or radial velocity Rossiter-McLaughlin methodology. With the ELTs we will be able to measure the obliquities for a sample of hundreds of small planets across a wide range of planetary radii and orbital periods, stellar masses and ages, and planetary and stellar multiplicity. Trends in the obliquity distribution with respect to these parameters will allow us to understand the dynamical histories of these planets, and where and when they form and migrate.Planetary SystemsGMT,TMT,obliquities, migration
Exoplanet Diversity in the era of space-based direct imaging missionsRavi, Amber V. Britt ( whitepaper discusses the diversity of exoplanets that could be detected by future observations, so that comparative exoplanetology can be performed in the upcoming
era of large space-based flagship missions. The primary focus will be on characterizing Earth-like worlds around Sun-like stars. However, we will also be able to characterize
companion planets in the system simultaneously. This will not only provide a contextual picture with regards to our Solar system, but also presents a unique opportunity to observe size dependent planetary atmospheres at different orbital distances. We propose a preliminary scheme based on chemical behavior of gases and condensates in a planet’s atmosphere that classifies them with respect to planetary radius and incident stellar flux.
Habitable zone predictions and how to test themRamses; You can also contact me here about co-authoring/co-signing or any other questions/comments you may have.20+ co-authors/co-signersOk, but we need more co-signers at this pointYes, as many as possibleThe habitable zone (HZ) is the region around a star(s) where standing bodies of water could exist on the surface of a rocky planet. The classical HZ definition makes a number of assumptions common to the Earth, including assuming that the most important greenhouse gases for habitable planets are CO2 and H2O, habitable planets orbit main-sequence stars, and that the carbonate-silicate cycle is a universal process on potentially habitable planets. Here, we discuss these and other predictions for the habitable zone and the observations that are needed to test them. We also, for the first time, argue why A-stars may be interesting HZ prospects. Instead of relying on unverified extrapolations from our Earth, we argue that future habitability studies require first principles approaches where temporal, spatial, physical, chemical, and biological systems are dynamically coupled. We also discuss how next-generation missions are only the beginning of a much more data-filled era in the not-too-distant future, when possibly hundreds - thousands of HZ planets will yield the statistical data we need to go beyond being able to find habitable zone planets to actually determining which ones are most likely to exhibit life. Planetary Habitability, The Search for Lifehabitable zone, dynamic habitability
Modeling Debris Disk EvolutionAndras
Dániel Apai, Nicholas P. Ballering, Charles A. Beichman, Mark Booth, Christine H. Chen,
John Debes, Steve Ertel, Paul G. Kalas, Grant M. Kennedy, Quentin Kral, Sebastiaan
Krijt, Alexander V. Krivov, Marc J. Kuchner, Jarron M. Leisenring, Torsten Löhne,
Wladimir Lyra, Meredith A. MacGregor, Bertrand Mennesson, Erika R. Nesvold,
George H. Rieke, Aki Roberge, Glenn H. Schneider, Christopher C. Stark, Kate Y. L. Su,
David J. Wilner, Mark C. Wyatt, Marie Ygouf, Andrew N. Youdin
Understanding the formation, evolution, diversity, and architectures of planetary systems requires detailed knowledge of all of their components. The past decade has
shown a remarkable increase in the number of known exo-planets and debris disks, i.e., populations of circumstellar planetes- imals and dust roughly analogous to our
solar system’s Kuiper-belt, asteroid-belt, and zodiacal dust. Technological advances have also allowed us to image over a dozen exo-planets and spatially resolve more
than a hundred debris disks, some around the same stars. Additionally, ground-based interferometric observations have revealed the existence of zodiacal dust around
other stars. Debris disks provide an ideal laboratory for studying the formation and short- and long-term evolution of their circumstellar systems. With the launch of JWST
and WFIRST, the next decade promises to deliver a wealth of new information on the nearest planetary systems. Parallel advances in the- oretical/numerical modeling
will be necessary to interpret these new datasets fully. Additionally, missions planned to image Earth-like planets directly will also benefit from detailed models of dust
production in exo-zodiacal belts, particularly if they are designed to image these belts as well as planets.
Debris DisksDebris Disks, Exoplanets, Modeling
Impacts of quantum chemistry calculations on exoplanetary science, planetary astronomy, and astrophysicsDer-you Kaoder-you.kao@nasa.govMarko Gacesa, Renata Wentzcovitch, Shawn Domagal-Goldman, Ravi K. Kopparapu, Stephen J. Klippenstein, Steven B. Charnley, Wade G. HenningYesYesOne-dimension photochemical models are a key tool in assessing the composition and climates of a variety of worlds, including rocky and gaseous planets, and planets in and beyond the Solar System. Such models draw knowledge from rate coefficients and products measured in the laboratory, or estimated with quantum chemical (sometimes called ab initio or first principle) transition state theory calculations. These models are then validated against detailed measurements on Earth, or from missions to other planets (e.g., Cassini-Huygens at Titan and Saturn [Vuitton, 2018]). Similarly, the environments that exist in astrophysical environments, such as the interstellar medium or the circumstellar disks, is very different from those traditionally probed in laboratory chemical kinetics studies. However, many of the laboratory experiments have been driven by funding to study atmospheric chemistry relevant to human health or the management of Earth’s climate, and the detailed measurements from missions are most relevant to the planets those missions visit. We anticipate a much broader set of chemical environments to exist on exoplanets, necessitating a need for knowledge of a similarly broadened set of chemical reactions. This is where quantum mechanical theory, applied to these reactions via well-validated chemical kinetics models, can fill a critical knowledge gap.Planetary Systems and Stars & Stellar EvolutionExoplanets, Modeling
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