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Witze A. JWST gets best view yet of planet in hotly pursued star system. Nature 2023; 616:18. [PMID: 36973460 DOI: 10.1038/d41586-023-00876-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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Changeat Q, Edwards B, Al-Refaie AF, Tsiaras A, Waldmann IP, Tinetti G. Disentangling atmospheric compositions of K2-18 b with next generation facilities. EXPERIMENTAL ASTRONOMY 2021; 53:391-416. [PMID: 35673553 PMCID: PMC9166872 DOI: 10.1007/s10686-021-09794-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 08/20/2021] [Indexed: 06/15/2023]
Abstract
Recent analysis of the planet K2-18 b has shown the presence of water vapour in its atmosphere. While the H2O detection is significant, the Hubble Space Telescope (HST) WFC3 spectrum suggests three possible solutions of very different nature which can equally match the data. The three solutions are a primary cloudy atmosphere with traces of water vapour (cloudy sub-Neptune), a secondary atmosphere with a substantial amount (up to 50% Volume Mixing Ratio) of H2O (icy/water world) and/or an undetectable gas such as N2 (super-Earth). Additionally, the atmospheric pressure and the possible presence of a liquid/solid surface cannot be investigated with currently available observations. In this paper we used the best fit parameters from Tsiaras et al. (Nat. Astron. 3, 1086, 2019) to build James Webb Space Telescope (JWST) and Ariel simulations of the three scenarios. We have investigated 18 retrieval cases, which encompass the three scenarios and different observational strategies with the two observatories. Retrieval results show that twenty combined transits should be enough for the Ariel mission to disentangle the three scenarios, while JWST would require only two transits if combining NIRISS and NIRSpec data. This makes K2-18 b an ideal target for atmospheric follow-ups by both facilities and highlights the capabilities of the next generation of space-based infrared observatories to provide a complete picture of low mass planets.
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Affiliation(s)
- Quentin Changeat
- Department of Physics and Astronomy, University College London, London, UK
| | - Billy Edwards
- Department of Physics and Astronomy, University College London, London, UK
| | - Ahmed F. Al-Refaie
- Department of Physics and Astronomy, University College London, London, UK
| | - Angelos Tsiaras
- Department of Physics and Astronomy, University College London, London, UK
| | - Ingo P. Waldmann
- Department of Physics and Astronomy, University College London, London, UK
| | - Giovanna Tinetti
- Department of Physics and Astronomy, University College London, London, UK
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Bean JL, Raymond SN, Owen JE. The Nature and Origins of Sub-Neptune Size Planets. JOURNAL OF GEOPHYSICAL RESEARCH. PLANETS 2021; 126:e2020JE006639. [PMID: 33680689 PMCID: PMC7900964 DOI: 10.1029/2020je006639] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 10/02/2020] [Accepted: 10/21/2020] [Indexed: 06/12/2023]
Abstract
Planets intermediate in size between the Earth and Neptune, and orbiting closer to their host stars than Mercury does the Sun, are the most common type of planet revealed by exoplanet surveys over the last quarter century. Results from NASA's Kepler mission have revealed a bimodality in the radius distribution of these objects, with a relative underabundance of planets between 1.5 and 2.0R ⊕ . This bimodality suggests that sub-Neptunes are mostly rocky planets that were born with primary atmospheres a few percent by mass accreted from the protoplanetary nebula. Planets above the radius gap were able to retain their atmospheres ("gas-rich super-Earths"), while planets below the radius gap lost their atmospheres and are stripped cores ("true super-Earths"). The mechanism that drives atmospheric loss for these planets remains an outstanding question, with photoevaporation and core-powered mass loss being the prime candidates. As with the mass-loss mechanism, there are two contenders for the origins of the solids in sub-Neptune planets: the migration model involves the growth and migration of embryos from beyond the ice line, while the drift model involves inward-drifting pebbles that coagulate to form planets close-in. Atmospheric studies have the potential to break degeneracies in interior structure models and place additional constraints on the origins of these planets. However, most atmospheric characterization efforts have been confounded by aerosols. Observations with upcoming facilities are expected to finally reveal the atmospheric compositions of these worlds, which are arguably the first fundamentally new type of planetary object identified from the study of exoplanets.
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Affiliation(s)
- Jacob L. Bean
- Department of Astronomy & AstrophysicsUniversity of ChicagoChicagoILUSA
| | - Sean N. Raymond
- Laboratoire d'Astrophysique de BordeauxCNRS and Université de BordeauxPessacFrance
| | - James E. Owen
- Department of PhysicsAstrophysics GroupImperial College LondonLondonUK
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Turbet M, Bolmont E, Bourrier V, Demory BO, Leconte J, Owen J, Wolf ET. A Review of Possible Planetary Atmospheres in the TRAPPIST-1 System. SPACE SCIENCE REVIEWS 2020; 216:100. [PMID: 32764836 PMCID: PMC7378127 DOI: 10.1007/s11214-020-00719-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 07/04/2020] [Indexed: 06/11/2023]
Abstract
TRAPPIST-1 is a fantastic nearby (∼39.14 light years) planetary system made of at least seven transiting terrestrial-size, terrestrial-mass planets all receiving a moderate amount of irradiation. To date, this is the most observationally favourable system of potentially habitable planets known to exist. Since the announcement of the discovery of the TRAPPIST-1 planetary system in 2016, a growing number of techniques and approaches have been used and proposed to characterize its true nature. Here we have compiled a state-of-the-art overview of all the observational and theoretical constraints that have been obtained so far using these techniques and approaches. The goal is to get a better understanding of whether or not TRAPPIST-1 planets can have atmospheres, and if so, what they are made of. For this, we surveyed the literature on TRAPPIST-1 about topics as broad as irradiation environment, planet formation and migration, orbital stability, effects of tides and Transit Timing Variations, transit observations, stellar contamination, density measurements, and numerical climate and escape models. Each of these topics adds a brick to our understanding of the likely-or on the contrary unlikely-atmospheres of the seven known planets of the system. We show that (i) Hubble Space Telescope transit observations, (ii) bulk density measurements comparison with H2-rich planets mass-radius relationships, (iii) atmospheric escape modelling, and (iv) gas accretion modelling altogether offer solid evidence against the presence of hydrogen-dominated-cloud-free and cloudy-atmospheres around TRAPPIST-1 planets. This means that the planets are likely to have either (i) a high molecular weight atmosphere or (ii) no atmosphere at all. There are several key challenges ahead to characterize the bulk composition(s) of the atmospheres (if present) of TRAPPIST-1 planets. The main one so far is characterizing and correcting for the effects of stellar contamination. Fortunately, a new wave of observations with the James Webb Space Telescope and near-infrared high-resolution ground-based spectrographs on existing very large and forthcoming extremely large telescopes will bring significant advances in the coming decade.
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Affiliation(s)
- Martin Turbet
- Observatoire Astronomique de l'Université de Genève, 51 chemin de Pégase, 1290 Sauverny, Switzerland
| | - Emeline Bolmont
- Observatoire Astronomique de l'Université de Genève, 51 chemin de Pégase, 1290 Sauverny, Switzerland
| | - Vincent Bourrier
- Observatoire Astronomique de l'Université de Genève, 51 chemin de Pégase, 1290 Sauverny, Switzerland
| | - Brice-Olivier Demory
- Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland
| | - Jérémy Leconte
- Laboratoire d'astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
| | - James Owen
- Astrophysics Group, Department of Physics, Imperial College London, Prince Consort Rd, London, SW7 2AZ UK
| | - Eric T Wolf
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80309 USA
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Impact of Clouds and Hazes on the Simulated JWST Transmission Spectra of Habitable Zone Planets in the TRAPPIST-1 System. ACTA ACUST UNITED AC 2019. [DOI: 10.3847/1538-4357/ab5862] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Evolved Climates and Observational Discriminants for the TRAPPIST-1 Planetary System. ACTA ACUST UNITED AC 2018. [DOI: 10.3847/1538-4357/aae36a] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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8
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10
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Ground-based Optical Transmission Spectroscopy of the Small, Rocky Exoplanet GJ 1132b. ACTA ACUST UNITED AC 2018. [DOI: 10.3847/1538-3881/aac6dd] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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11
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Meadows VS, Reinhard CT, Arney GN, Parenteau MN, Schwieterman EW, Domagal-Goldman SD, Lincowski AP, Stapelfeldt KR, Rauer H, DasSarma S, Hegde S, Narita N, Deitrick R, Lustig-Yaeger J, Lyons TW, Siegler N, Grenfell JL. Exoplanet Biosignatures: Understanding Oxygen as a Biosignature in the Context of Its Environment. ASTROBIOLOGY 2018; 18:630-662. [PMID: 29746149 PMCID: PMC6014580 DOI: 10.1089/ast.2017.1727] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 12/15/2017] [Indexed: 05/04/2023]
Abstract
We describe how environmental context can help determine whether oxygen (O2) detected in extrasolar planetary observations is more likely to have a biological source. Here we provide an in-depth, interdisciplinary example of O2 biosignature identification and observation, which serves as the prototype for the development of a general framework for biosignature assessment. Photosynthetically generated O2 is a potentially strong biosignature, and at high abundance, it was originally thought to be an unambiguous indicator for life. However, as a biosignature, O2 faces two major challenges: (1) it was only present at high abundance for a relatively short period of Earth's history and (2) we now know of several potential planetary mechanisms that can generate abundant O2 without life being present. Consequently, our ability to interpret both the presence and absence of O2 in an exoplanetary spectrum relies on understanding the environmental context. Here we examine the coevolution of life with the early Earth's environment to identify how the interplay of sources and sinks may have suppressed O2 release into the atmosphere for several billion years, producing a false negative for biologically generated O2. These studies suggest that planetary characteristics that may enhance false negatives should be considered when selecting targets for biosignature searches. We review the most recent knowledge of false positives for O2, planetary processes that may generate abundant atmospheric O2 without a biosphere. We provide examples of how future photometric, spectroscopic, and time-dependent observations of O2 and other aspects of the planetary environment can be used to rule out false positives and thereby increase our confidence that any observed O2 is indeed a biosignature. These insights will guide and inform the development of future exoplanet characterization missions. Key Words: Biosignatures-Oxygenic photosynthesis-Exoplanets-Planetary atmospheres. Astrobiology 18, 630-662.
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Affiliation(s)
- Victoria S. Meadows
- Department of Astronomy, University of Washington, Seattle, Washington
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
| | - Christopher T. Reinhard
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia
- NASA Astrobiology Institute, Alternative Earths Team, Riverside, California
| | - Giada N. Arney
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland
| | - Mary N. Parenteau
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- NASA Ames Research Center, Exobiology Branch, Mountain View, California
| | - Edward W. Schwieterman
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- NASA Astrobiology Institute, Alternative Earths Team, Riverside, California
- Department of Earth Sciences, University of California, Riverside, California
- NASA Postdoctoral Program, Universities Space Research Association, Columbia, Maryland
- Blue Marble Space Institute of Science, Seattle, Washington
| | - Shawn D. Domagal-Goldman
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- Planetary Environments Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland
| | - Andrew P. Lincowski
- Department of Astronomy, University of Washington, Seattle, Washington
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
| | - Karl R. Stapelfeldt
- NASA Exoplanet Exploration Program, Jet Propulsion Laboratory/California Institute of Technology, Pasadena, California
| | - Heike Rauer
- German Aerospace Center, Institute of Planetary Research, Extrasolar Planets and Atmospheres, Berlin, Germany
| | - Shiladitya DasSarma
- Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Maryland
- Institute of Marine and Environmental Technology, University System of Baltimore, Maryland
| | - Siddharth Hegde
- Carl Sagan Institute, Cornell University, Ithaca, New York
- Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, New York
| | - Norio Narita
- Department of Astronomy, The University of Tokyo, Tokyo, Japan
- Astrobiology Center, NINS, Tokyo, Japan
- National Astronomical Observatory of Japan, NINS, Tokyo, Japan
| | - Russell Deitrick
- Department of Astronomy, University of Washington, Seattle, Washington
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
| | - Jacob Lustig-Yaeger
- Department of Astronomy, University of Washington, Seattle, Washington
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
| | - Timothy W. Lyons
- NASA Astrobiology Institute, Alternative Earths Team, Riverside, California
- Department of Earth Sciences, University of California, Riverside, California
| | - Nicholas Siegler
- NASA Exoplanet Exploration Program, Jet Propulsion Laboratory/California Institute of Technology, Pasadena, California
| | - J. Lee Grenfell
- German Aerospace Center, Institute of Planetary Research, Extrasolar Planets and Atmospheres, Berlin, Germany
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Rushby AJ, Johnson M, Mills BJW, Watson AJ, Claire MW. Long-Term Planetary Habitability and the Carbonate-Silicate Cycle. ASTROBIOLOGY 2018; 18:469-480. [PMID: 29791235 DOI: 10.1089/ast.2017.1693] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The potential habitability of an exoplanet is traditionally assessed by determining whether its orbit falls within the circumstellar "habitable zone" of its star, defined as the distance at which water could be liquid on the surface of a planet (Kopparapu et al., 2013 ). Traditionally, these limits are determined by radiative-convective climate models, which are used to predict surface temperatures at user-specified levels of greenhouse gases. This approach ignores the vital question of the (bio)geochemical plausibility of the proposed chemical abundances. Carbon dioxide is the most important greenhouse gas in Earth's atmosphere in terms of regulating planetary temperature, with the long-term concentration controlled by the balance between volcanic outgassing and the sequestration of CO2 via chemical weathering and sedimentation, as modulated by ocean chemistry, circulation, and biological (microbial) productivity. We developed a model that incorporates key aspects of Earth's short- and long-term biogeochemical carbon cycle to explore the potential changes in the CO2 greenhouse due to variance in planet size and stellar insolation. We find that proposed changes in global topography, tectonics, and the hydrological cycle on larger planets result in proportionally greater surface temperatures for a given incident flux. For planets between 0.5 and 2 R⊕, the effect of these changes results in average global surface temperature deviations of up to 20 K, which suggests that these relationships must be considered in future studies of planetary habitability. Key Words: Planets-Atmospheres-Carbon dioxide-Biogeochemistry. Astrobiology 18, 469-480.
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Affiliation(s)
- Andrew J Rushby
- 1 NASA Ames Research Center , Moffett Field, California, USA
- 2 School of Environmental Science, University of East Anglia , Norwich, UK
| | - Martin Johnson
- 2 School of Environmental Science, University of East Anglia , Norwich, UK
- 3 Centre for Environment, Fisheries and Aquaculture Sciences , Lowestoft, UK
| | | | - Andrew J Watson
- 5 College of Life and Environmental Sciences, University of Exeter , Exeter, UK
| | - Mark W Claire
- 6 School of Earth and Environmental Sciences, University of St. Andrews , St. Andrews, UK
- 7 Centre for Exoplanet Science, University of St. Andrews , St. Andrews, UK
- 8 Blue Marble Space Institute of Science , Seattle, Washington, USA
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14
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Observational Techniques with Transiting Exoplanetary Atmospheres. ASTROPHYSICS AND SPACE SCIENCE LIBRARY 2018. [DOI: 10.1007/978-3-319-89701-1_1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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15
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Atmospheric escape from the TRAPPIST-1 planets and implications for habitability. Proc Natl Acad Sci U S A 2017; 115:260-265. [PMID: 29284746 DOI: 10.1073/pnas.1708010115] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The presence of an atmosphere over sufficiently long timescales is widely perceived as one of the most prominent criteria associated with planetary surface habitability. We address the crucial question of whether the seven Earth-sized planets transiting the recently discovered ultracool dwarf star TRAPPIST-1 are capable of retaining their atmospheres. To this effect, we carry out numerical simulations to characterize the stellar wind of TRAPPIST-1 and the atmospheric ion escape rates for all of the seven planets. We also estimate the escape rates analytically and demonstrate that they are in good agreement with the numerical results. We conclude that the outer planets of the TRAPPIST-1 system are capable of retaining their atmospheres over billion-year timescales. The consequences arising from our results are also explored in the context of abiogenesis, biodiversity, and searches for future exoplanets. In light of the many unknowns and assumptions involved, we recommend that these conclusions must be interpreted with due caution.
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A Search for Additional Bodies in the GJ 1132 Planetary System from 21 Ground-based Transits and a 100-hrSpitzerCampaign. ACTA ACUST UNITED AC 2017. [DOI: 10.3847/1538-3881/aa855b] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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19
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Temporal Evolution of the High-energy Irradiation and Water Content of TRAPPIST-1 Exoplanets. ACTA ACUST UNITED AC 2017. [DOI: 10.3847/1538-3881/aa859c] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Cataldi G, Brandeker A, Thébault P, Singer K, Ahmed E, de Vries BL, Neubeck A, Olofsson G. Searching for Biosignatures in Exoplanetary Impact Ejecta. ASTROBIOLOGY 2017; 17:721-746. [PMID: 28692303 DOI: 10.1089/ast.2015.1437] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
With the number of confirmed rocky exoplanets increasing steadily, their characterization and the search for exoplanetary biospheres are becoming increasingly urgent issues in astrobiology. To date, most efforts have concentrated on the study of exoplanetary atmospheres. Instead, we aim to investigate the possibility of characterizing an exoplanet (in terms of habitability, geology, presence of life, etc.) by studying material ejected from the surface during an impact event. For a number of impact scenarios, we estimate the escaping mass and assess its subsequent collisional evolution in a circumstellar orbit, assuming a Sun-like host star. We calculate the fractional luminosity of the dust as a function of time after the impact event and study its detectability with current and future instrumentation. We consider the possibility to constrain the dust composition, giving information on the geology or the presence of a biosphere. As examples, we investigate whether calcite, silica, or ejected microorganisms could be detected. For a 20 km diameter impactor, we find that the dust mass escaping the exoplanet is roughly comparable to the zodiacal dust, depending on the exoplanet's size. The collisional evolution is best modeled by considering two independent dust populations, a spalled population consisting of nonmelted ejecta evolving on timescales of millions of years, and dust recondensed from melt or vapor evolving on much shorter timescales. While the presence of dust can potentially be inferred with current telescopes, studying its composition requires advanced instrumentation not yet available. The direct detection of biological matter turns out to be extremely challenging. Despite considerable difficulties (small dust masses, noise such as exozodiacal dust, etc.), studying dusty material ejected from an exoplanetary surface might become an interesting complement to atmospheric studies in the future. Key Words: Biosignatures-Exoplanets-Impacts-Interplanetary dust-Remote sensing. Astrobiology 17, 721-746.
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Affiliation(s)
- Gianni Cataldi
- 1 AlbaNova University Centre, Stockholm University , Department of Astronomy, Stockholm, Sweden
- 2 Stockholm University Astrobiology Centre , Stockholm, Sweden
| | - Alexis Brandeker
- 1 AlbaNova University Centre, Stockholm University , Department of Astronomy, Stockholm, Sweden
- 2 Stockholm University Astrobiology Centre , Stockholm, Sweden
| | - Philippe Thébault
- 3 LESIA-Observatoire de Paris, UPMC Univ. Paris 06, Univ. Paris-Diderot , Paris, France
| | - Kelsi Singer
- 4 Southwest Research Institute , Boulder, Colorado, USA
| | - Engy Ahmed
- 2 Stockholm University Astrobiology Centre , Stockholm, Sweden
- 5 Royal Institute of Technology (KTH) , Science for Life Laboratory, Solna, Sweden
- 6 Stockholm University , Department of Geological Sciences, Stockholm, Sweden
| | - Bernard L de Vries
- 1 AlbaNova University Centre, Stockholm University , Department of Astronomy, Stockholm, Sweden
- 2 Stockholm University Astrobiology Centre , Stockholm, Sweden
- 7 Scientific Support Office, Directorate of Science, European Space Research and Technology Centre (ESA/ESTEC) , Noordwijk, The Netherlands
| | - Anna Neubeck
- 2 Stockholm University Astrobiology Centre , Stockholm, Sweden
- 6 Stockholm University , Department of Geological Sciences, Stockholm, Sweden
| | - Göran Olofsson
- 1 AlbaNova University Centre, Stockholm University , Department of Astronomy, Stockholm, Sweden
- 2 Stockholm University Astrobiology Centre , Stockholm, Sweden
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Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1. Nature 2017; 542:456-460. [PMID: 28230125 PMCID: PMC5330437 DOI: 10.1038/nature21360] [Citation(s) in RCA: 142] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 12/21/2016] [Indexed: 11/09/2022]
Abstract
One focus of modern astronomy is to detect temperate terrestrial exoplanets well-suited
for atmospheric characterisation. A milestone was recently achieved with the
detection of three Earth-sized planets transiting (i.e. passing in front of) a
star just 8% the mass of the Sun 12 parsecs away1. Indeed, the transiting configuration of these planets combined
with the Jupiter-like size of their host star - named TRAPPIST-1 - makes
possible in-depth studies of their atmospheric properties with current and
future astronomical facilities1,2,3.
Here we report the results of an intensive photometric monitoring campaign of
that star from the ground and with the Spitzer Space Telescope. Our observations
reveal that at least seven planets with sizes and masses similar to the Earth
revolve around TRAPPIST-1. The six inner planets form a near-resonant chain such
that their orbital periods (1.51, 2.42, 4.04, 6.06, 9.21, 12.35 days) are near
ratios of small integers. This architecture suggests that the planets formed
farther from the star and migrated inward4,5. The seven planets have
equilibrium temperatures low enough to make possible liquid water on their
surfaces6,7,8.
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Wakeford HR, Sing DK, Kataria T, Deming D, Nikolov N, Lopez ED, Tremblin P, Amundsen DS, Lewis NK, Mandell AM, Fortney JJ, Knutson H, Benneke B, Evans TM. HAT-P-26b: A Neptune-mass exoplanet with a well-constrained heavy element abundance. Science 2017; 356:628-631. [DOI: 10.1126/science.aah4668] [Citation(s) in RCA: 155] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 04/20/2017] [Indexed: 11/02/2022]
Affiliation(s)
- Hannah R. Wakeford
- NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, USA
| | - David K. Sing
- Astrophysics Group, University of Exeter, Physics Building, Stocker Road, Exeter, Devon, EX4 4QL UK
| | - Tiffany Kataria
- NASA Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
| | - Drake Deming
- Department of Astronomy, University of Maryland, College Park, MD 20742, USA
| | - Nikolay Nikolov
- Astrophysics Group, University of Exeter, Physics Building, Stocker Road, Exeter, Devon, EX4 4QL UK
| | - Eric D. Lopez
- NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, USA
- Institute for Astronomy, Royal Observatory Edinburgh, University of Edinburgh, Blackford Hill, Edinburgh, UK
| | - Pascal Tremblin
- Maison de la Simulation, Commissariat à l’énergie atomique et aux énergies alternatives (CEA), CNRS, Université Paris-Sud, Université Versailles Saint-Quentin-en-Yvelines (UVSQ), Université Paris-Saclay, 91191 Gif-sur-Yvette, France
| | - David S. Amundsen
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10025, USA
- NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, USA
| | - Nikole K. Lewis
- Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
| | - Avi M. Mandell
- NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, USA
| | - Jonathan J. Fortney
- Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064, USA
| | - Heather Knutson
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - Björn Benneke
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - Thomas M. Evans
- Astrophysics Group, University of Exeter, Physics Building, Stocker Road, Exeter, Devon, EX4 4QL UK
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O’Malley-James JT, Kaltenegger L. UV surface habitability of the TRAPPIST-1 system. ACTA ACUST UNITED AC 2017. [DOI: 10.1093/mnrasl/slx047] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Pale Orange Dots: The Impact of Organic Haze on the Habitability and Detectability of Earthlike Exoplanets. ACTA ACUST UNITED AC 2017. [DOI: 10.3847/1538-4357/836/1/49] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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