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Wakeford HR, Dalba PA. The exoplanet perspective on future ice giant exploration. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2020; 378:20200054. [PMID: 33161853 DOI: 10.1098/rsta.2020.0054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/06/2020] [Indexed: 05/20/2023]
Abstract
Exoplanets number in their thousands, and the number is ever increasing with the advent of new surveys and improved instrumentation. One of the most surprising things we have learnt from these discoveries is not that small-rocky planets in their stars habitable zones are likely to be common, but that the most typical size of exoplanets is that not seen in our solar system-radii between that of Neptune and the Earth dubbed mini-Neptunes and super-Earths. In fact, a transiting exoplanet is four times as likely to be in this size regime than that of any giant planet in our solar system. Investigations into the atmospheres of giant hydrogen/helium dominated exoplanets has pushed down to Neptune and mini-Neptune-sized worlds revealing molecular absorption from water, scattering and opacity from clouds, and measurements of atmospheric abundances. However, unlike measurements of Jupiter, or even Saturn sized worlds, the smaller giants lack a ground truth on what to expect or interpret from their measurements. How did these sized worlds form and evolve and was it different from their larger counterparts? What is their internal composition and how does that impact their atmosphere? What informs the energy budget of these distant worlds? In this we discuss what characteristics we can measure for exoplanets, and why a mission to the ice giants in our solar system is the logical next step for understanding exoplanets. This article is part of a discussion meeting issue 'Future exploration of ice giant systems'.
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Affiliation(s)
- H R Wakeford
- School of Physics, University of Bristol, HH Wills Laboratory, Tyndall Avenue, Bristol BS8 1TL, UK
| | - P A Dalba
- Department of Earth and Planetary Sciences, University of California Riverside, 900 University Avenue, Riverside CA 92521, USA
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Was Jupiter born beyond the current orbits of Neptune and Pluto? Proc Natl Acad Sci U S A 2020; 117:16716-16719. [DOI: 10.1073/pnas.2011609117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Ercolano B, Pascucci I. The dispersal of planet-forming discs: theory confronts observations. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170114. [PMID: 28484640 PMCID: PMC5414277 DOI: 10.1098/rsos.170114] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/29/2017] [Indexed: 06/02/2023]
Abstract
Discs of gas and dust around million-year-old stars are a by-product of the star formation process and provide the raw material to form planets. Hence, their evolution and dispersal directly impact what type of planets can form and affect the final architecture of planetary systems. Here, we review empirical constraints on disc evolution and dispersal with special emphasis on transition discs, a subset of discs that appear to be caught in the act of clearing out planet-forming material. Along with observations, we summarize theoretical models that build our physical understanding of how discs evolve and disperse and discuss their significance in the context of the formation and evolution of planetary systems. By confronting theoretical predictions with observations, we also identify the most promising areas for future progress.
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Affiliation(s)
- Barbara Ercolano
- Universitäts-Sternwarte München, Scheinerstraße 1, 81679 München, Germany
- Excellence Cluster Origin and Structure of the Universe, Boltzmannstrasse 2, 85748 Garching bei München, Germany
| | - Ilaria Pascucci
- Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721, USA
- Earths in Other Solar Systems Team, NASA Nexus for Exoplanet System Science
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Madhusudhan N, Agúndez M, Moses JI, Hu Y. Exoplanetary Atmospheres-Chemistry, Formation Conditions, and Habitability. SPACE SCIENCE REVIEWS 2016; 205:285-348. [PMID: 28057962 PMCID: PMC5207327 DOI: 10.1007/s11214-016-0254-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Characterizing the atmospheres of extrasolar planets is the new frontier in exoplanetary science. The last two decades of exoplanet discoveries have revealed that exoplanets are very common and extremely diverse in their orbital and bulk properties. We now enter a new era as we begin to investigate the chemical diversity of exoplanets, their atmospheric and interior processes, and their formation conditions. Recent developments in the field have led to unprecedented advancements in our understanding of atmospheric chemistry of exoplanets and the implications for their formation conditions. We review these developments in the present work. We review in detail the theory of atmospheric chemistry in all classes of exoplanets discovered to date, from highly irradiated gas giants, ice giants, and super-Earths, to directly imaged giant planets at large orbital separations. We then review the observational detections of chemical species in exoplanetary atmospheres of these various types using different methods, including transit spectroscopy, Doppler spectroscopy, and direct imaging. In addition to chemical detections, we discuss the advances in determining chemical abundances in these atmospheres and how such abundances are being used to constrain exoplanetary formation conditions and migration mechanisms. Finally, we review recent theoretical work on the atmospheres of habitable exoplanets, followed by a discussion of future outlook of the field.
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Affiliation(s)
- Nikku Madhusudhan
- Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
| | - Marcelino Agúndez
- Instituto de Ciencia de Materiales de Madrid, CSIC, C/Sor Juana Inés de la Cruz 3, 28049 Cantoblanco, Spain,
| | - Julianne I Moses
- Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301, USA,
| | - Yongyun Hu
- Laboratory for Climate and Ocean-Atmosphere Sciences, Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, China,
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Dalba PA, Muirhead PS, Fortney JJ, Hedman MM, Nicholson PD, Veyette MJ. THE TRANSIT TRANSMISSION SPECTRUM OF A COLD GAS GIANT PLANET. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/0004-637x/814/2/154] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Kreidberg L, Line MR, Bean JL, Stevenson KB, Désert JM, Madhusudhan N, Fortney JJ, Barstow JK, Henry GW, Williamson MH, Showman AP. A DETECTION OF WATER IN THE TRANSMISSION SPECTRUM OF THE HOT JUPITER WASP-12b AND IMPLICATIONS FOR ITS ATMOSPHERIC COMPOSITION. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/0004-637x/814/1/66] [Citation(s) in RCA: 186] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Mousis O, Chassefière E, Holm NG, Bouquet A, Waite JH, Geppert WD, Picaud S, Aikawa Y, Ali-Dib M, Charlou JL, Rousselot P. Methane clathrates in the solar system. ASTROBIOLOGY 2015; 15:308-326. [PMID: 25774974 DOI: 10.1089/ast.2014.1189] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We review the reservoirs of methane clathrates that may exist in the different bodies of the Solar System. Methane was formed in the interstellar medium prior to having been embedded in the protosolar nebula gas phase. This molecule was subsequently trapped in clathrates that formed from crystalline water ice during the cooling of the disk and incorporated in this form into the building blocks of comets, icy bodies, and giant planets. Methane clathrates may play an important role in the evolution of planetary atmospheres. On Earth, the production of methane in clathrates is essentially biological, and these compounds are mostly found in permafrost regions or in the sediments of continental shelves. On Mars, methane would more likely derive from hydrothermal reactions with olivine-rich material. If they do exist, martian methane clathrates would be stable only at depth in the cryosphere and sporadically release some methane into the atmosphere via mechanisms that remain to be determined. In the case of Titan, most of its methane probably originates from the protosolar nebula, where it would have been trapped in the clathrates agglomerated by the satellite's building blocks. Methane clathrates are still believed to play an important role in the present state of Titan. Their presence is invoked in the satellite's subsurface as a means of replenishing its atmosphere with methane via outgassing episodes. The internal oceans of Enceladus and Europa also provide appropriate thermodynamic conditions that allow formation of methane clathrates. In turn, these clathrates might influence the composition of these liquid reservoirs. Finally, comets and Kuiper Belt Objects might have formed from the agglomeration of clathrates and pure ices in the nebula. The methane observed in comets would then result from the destabilization of clathrate layers in the nuclei concurrent with their approach to perihelion. Thermodynamic equilibrium calculations show that methane-rich clathrate layers may exist on Pluto as well. Key Words: Methane clathrate-Protosolar nebula-Terrestrial planets-Outer Solar System. Astrobiology 15, 308-326.
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Affiliation(s)
- Olivier Mousis
- 1 Aix Marseille Université , CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, Marseille, France
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Ciesla FJ. SULFURIZATION OF IRON IN THE DYNAMIC SOLAR NEBULA AND IMPLICATIONS FOR PLANETARY COMPOSITIONS. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/2041-8205/800/1/l6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Lee EJ, Chiang E, Ormel CW. MAKE SUPER-EARTHS, NOT JUPITERS: ACCRETING NEBULAR GAS ONTO SOLID CORES AT 0.1 AU AND BEYOND. ACTA ACUST UNITED AC 2014. [DOI: 10.1088/0004-637x/797/2/95] [Citation(s) in RCA: 173] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Fletcher LN, Irwin PGJ, Barstow JK, de Kok RJ, Lee JM, Aigrain S. Exploring the diversity of Jupiter-class planets. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2014; 372:20130064. [PMID: 24664910 PMCID: PMC3982424 DOI: 10.1098/rsta.2013.0064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Of the 900+ confirmed exoplanets discovered since 1995 for which we have constraints on their mass (i.e. not including Kepler candidates), 75% have masses larger than Saturn (0.3 MJ), 53% are more massive than Jupiter and 67% are within 1 AU of their host stars. When Kepler candidates are included, Neptune-sized giant planets could form the majority of the planetary population. And yet the term 'hot Jupiter' fails to account for the incredible diversity of this class of astrophysical object, which exists on a continuum of giant planets from the cool jovians of our own Solar System to the highly irradiated, tidally locked hot roasters. We review theoretical expectations for the temperatures, molecular composition and cloud properties of hydrogen-dominated Jupiter-class objects under a variety of different conditions. We discuss the classification schemes for these Jupiter-class planets proposed to date, including the implications for our own Solar System giant planets and the pitfalls associated with compositional classification at this early stage of exoplanetary spectroscopy. We discuss the range of planetary types described by previous authors, accounting for (i) thermochemical equilibrium expectations for cloud condensation and favoured chemical stability fields; (ii) the metallicity and formation mechanism for these giant planets; (iii) the importance of optical absorbers for energy partitioning and the generation of a temperature inversion; (iv) the favoured photochemical pathways and expectations for minor species (e.g. saturated hydrocarbons and nitriles); (v) the unexpected presence of molecules owing to vertical mixing of species above their quench levels; and (vi) methods for energy and material redistribution throughout the atmosphere (e.g. away from the highly irradiated daysides of close-in giants). Finally, we discuss the benefits and potential flaws of retrieval techniques for establishing a family of atmospheric solutions that reproduce the available data, and the requirements for future spectroscopic characterization of a set of Jupiter-class objects to test our physical and chemical understanding of these planets.
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Affiliation(s)
- Leigh N. Fletcher
- Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK
| | - Patrick G. J. Irwin
- Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK
| | - Joanna K. Barstow
- Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK
| | - Remco J. de Kok
- SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
| | - Jae-Min Lee
- Institute for Theoretical Physics, University of Zurich, 8057 Zurich, Switzerland
| | - Suzanne Aigrain
- Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK
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Moses JI, Madhusudhan N, Visscher C, Freedman RS. CHEMICAL CONSEQUENCES OF THE C/O RATIO ON HOT JUPITERS: EXAMPLES FROM WASP-12b, COROT-2b, XO-1b, AND HD 189733b. THE ASTROPHYSICAL JOURNAL 2012; 763:25. [PMID: 30842680 PMCID: PMC6398958 DOI: 10.1088/0004-637x/763/1/25] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Motivated by recent spectroscopic evidence for carbon-rich atmospheres on some transiting exo-planets, we investigate the influence of the C/O ratio on the chemistry, composition, and spectra of extrasolar giant planets both from a thermochemical-equilibrium perspective and from consideration of disequilibrium processes like photochemistry and transport-induced quenching. We find that although CO is predicted to be a major atmospheric constituent on hot Jupiters for all C/O ratios, other oxygen-bearing molecules like H2O and CO2 are much more abundant when C/O < 1, whereas CH4, HCN, and C2H2 gain significantly in abundance when C/O > 1. Other notable species like N2 and NH3 that do not contain carbon or oxygen are relatively unaffected by the C/O ratio. Disequilibrium processes tend to enhance the abundance of CH4, NH3, HCN, and C2H2 over a wide range of C/O ratios. We compare the results of our models with secondary-eclipse photometric data from the Spitzer Space Telescope and conclude that (1) disequilibrium models with C/O ~ 1 are consistent with spectra of WASP-12b, XO-1b, and CoRoT-2b, confirming the possible carbon-rich nature of these planets, (2) spectra from HD 189733b are consistent with C/O ≲ 1, but as the assumed metallicity is increased above solar, the required C/O ratio must increase toward 1 to prevent too much H2O absorption, (3) species like HCN can have a significant influence on spectral behavior in the 3.6 and 8.0 μm Spitzer channels, potentially providing even more opacity than CH4 when C/O > 1, and (4) the very high CO2 abundance inferred for HD 189733b from near-infrared observations cannot be explained through equilibrium or disequilibrium chemistry in a hydrogen-dominated atmosphere. We discuss possible formation mechanisms for carbon-rich hot Jupiters, including scenarios in which the accretion of CO-rich, H2O-poor gas dominates the atmospheric envelope, and scenarios in which the planets accrete carbon-rich solids while migrating through disk regions inward of the snow line. The C/O ratio and bulk atmospheric metallicity provide important clues regarding the formation and evolution of the giant planets.
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Affiliation(s)
- J I Moses
- Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO, 80301, USA
| | - N Madhusudhan
- Department of Physics and Department of Astronomy, Yale University, New Haven, CT, 06520-8101, USA
| | - C Visscher
- Southwest Research Institute, Boulder, CO, 80302, USA
| | - R S Freedman
- SETI Institute, Mountain View, CA, 94043 and NASA Ames Research Center, Moffett Field, CA, 94035, USA
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Marty B, Chaussidon M, Wiens RC, Jurewicz AJG, Burnett DS. A 15N-poor isotopic composition for the solar system as shown by Genesis solar wind samples. Science 2011; 332:1533-6. [PMID: 21700869 DOI: 10.1126/science.1204656] [Citation(s) in RCA: 210] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Genesis mission sampled solar wind ions to document the elemental and isotopic compositions of the Sun and, by inference, of the protosolar nebula. Nitrogen was a key target element because the extent and origin of its isotopic variations in solar system materials remain unknown. Isotopic analysis of a Genesis Solar Wind Concentrator target material shows that implanted solar wind nitrogen has a (15)N/(14)N ratio of 2.18 ± 0.02 × 10(-3) (that is, ≈40% poorer in (15)N relative to terrestrial atmosphere). The (15)N/(14)N ratio of the protosolar nebula was 2.27 ± 0.03 × 10(-3), which is the lowest (15)N/(14)N ratio known for solar system objects. This result demonstrates the extreme nitrogen isotopic heterogeneity of the nascent solar system and accounts for the (15)N-depleted components observed in solar system reservoirs.
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Affiliation(s)
- B Marty
- Centre de Recherches Pétrographiques et Géochimiques (CRPG), Nancy Université, Vandoeuvre-lès-Nancy, France.
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Madhusudhan N, Harrington J, Stevenson KB, Nymeyer S, Campo CJ, Wheatley PJ, Deming D, Blecic J, Hardy RA, Lust NB, Anderson DR, Collier-Cameron A, Britt CBT, Bowman WC, Hebb L, Hellier C, Maxted PFL, Pollacco D, West RG. A high C/O ratio and weak thermal inversion in the atmosphere of exoplanet WASP-12b. Nature 2010; 469:64-7. [DOI: 10.1038/nature09602] [Citation(s) in RCA: 250] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 10/21/2010] [Indexed: 11/09/2022]
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Mousis O, Lunine JI, Picaud S, Cordier D. Volatile inventories in clathrate hydrates formed in the primordial nebula. Faraday Discuss 2010; 147:509-25; discussion 527-52. [DOI: 10.1039/c003658g] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Owen T, Niemann HB. The origin of Titan's atmosphere: some recent advances. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2009; 367:607-615. [PMID: 19019783 DOI: 10.1098/rsta.2008.0247] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
It is possible to make a consistent story for the origin of Titan's atmosphere starting with the birth of Titan in the Saturn subnebula. If we use comet nuclei as a model, Titan's nitrogen and methane could have easily been delivered by the ice that makes up approximately 50 per cent of its mass. If Titan's atmospheric hydrogen is derived from that ice, it is possible that Titan and comet nuclei are in fact made of the same protosolar ice. The noble gas abundances are consistent with relative abundances found in the atmospheres of Mars and Earth, the Sun, and the meteorites.
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Affiliation(s)
- Tobias Owen
- Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA.
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Guillot T, Hueso R. The composition of Jupiter: sign of a (relatively) late formation in a chemically evolved protosolar disc. ACTA ACUST UNITED AC 2006. [DOI: 10.1111/j.1745-3933.2006.00137.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Owen TC, Niemann H, Atreya S, Zolotov MY. Between heaven and Earth: the exploration of Titan. Faraday Discuss 2006; 133:387-91; discussion 427-52. [PMID: 17191458 DOI: 10.1039/b517174a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The atmosphere of Titan represents a bridge between the early solar nebula and atmospheres like ours. The low abundances of primordial noble gases in Titan's atmosphere relative to N2 suggest that the icy planetesimals that formed the satellite must have originated at temperatures higher than 75-100 K. Under these conditions, N2 would also be very poorly trapped and thus Titan's nitrogen, like ours, must have arrived as nitrogen compounds, of which ammonia was likely the major component. This temperature constraint also argues against the trapping of methane. Production of this gas on the satellite after formation appears reasonable based on terrestrial examples of serpentinization, disproportionation and reduction of carbon. These processes require rocks, water, suitable catalysts and the variety of primordial carbon compounds that were plausibly trapped in Titan's ices. Application of this same general scenario to Ganymede, Callisto, KBOs and conditions on the very early Earth seems promising.
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Affiliation(s)
- Tobias C Owen
- Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu 96822, USA.
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Owen T, Encrenaz T. Element Abundances and Isotope Ratios in the Giant Planets and Titan. SOLAR SYSTEM HISTORY FROM ISOTOPIC SIGNATURES OF VOLATILE ELEMENTS 2003. [DOI: 10.1007/978-94-010-0145-8_9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Zou Z, Ye J, Arakawa H. Role of R in Bi2RNbO7 (R = Y, Rare Earth): Effect on Band Structure and Photocatalytic Properties. J Phys Chem B 2001. [DOI: 10.1021/jp012982f] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zhigang Zou
- Photoreaction Control Research Center (PCRC), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan, and Materials Engineering Laboratory (MEL), National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Jinhua Ye
- Photoreaction Control Research Center (PCRC), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan, and Materials Engineering Laboratory (MEL), National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Hironori Arakawa
- Photoreaction Control Research Center (PCRC), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan, and Materials Engineering Laboratory (MEL), National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
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Abstract
Laboratory experiments on the trapping of gases by ice forming at low temperatures implicate comets as major carriers of the heavy noble gases to the inner planets. These icy planetesimals may also have brought the nitrogen compounds that ultimately produced atmospheric N2. However, if the sample of three comets analyzed so far is typical, the Earth's oceans cannot have been produced by comets alone, they require an additional source of water with low D/H. The highly fractionated neon in the Earth's atmosphere may also indicate the importance of non-icy carriers of volatiles. The most important additional carrier is probably the rocky material comprising the bulk of the mass of these planets. Venus may require a contribution from icy planetesimals formed at the low temperatures characteristic of the Kuiper Belt.
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Affiliation(s)
- T C Owen
- University of Hawaii, Institute for Astronomy, Honolulu, Hawaii 96822, USA
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Affiliation(s)
- Adam P. Showman
- National Research Council (NRC)/NASA Ames Research Center, Mail Stop 245-3, Moffett Field, CA 94035–1000, USA
| | - Timothy E. Dowling
- Comparative Planetology Laboratory, University of Louisville, 211 Sackett Hall, Louisville, KY 40292, USA
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Mahaffy PR, Niemann HB, Alpert A, Atreya SK, Demick J, Donahue TM, Harpold DN, Owen TC. Noble gas abundance and isotope ratios in the atmosphere of Jupiter from the Galileo Probe Mass Spectrometer. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/1999je001224] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Affiliation(s)
- David J. Stevenson
- David J. Stevenson is the George van Osdol Professor of Planetary Science at the California Institute of Technology. He received his Ph.D. in theoretical physics at Cornell in 1976, working on the interior of Jupiter, but has since explored all aspects of planetary origin, evolution, and structure, including studies of planet Earth and satellites of the giant planets
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Ball P. Giant mistake. Nature 1999. [DOI: 10.1038/news991118-10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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