Methane and its isotopologues on Saturn from Cassini/CIRS observations
TL;DR: In this paper, a line-by-line approach was used to evaluate the reliability of the retrieved quantities, which showed no hemispherical asymmetries or latitudinal variability.
About: This article is published in Icarus.The article was published on 2009-02-01. It has received 181 citations till now. The article focuses on the topics: Jovian.
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University of Chicago1, University of Colorado Boulder2, University of California, Santa Cruz3, University of Cambridge4, University of Arizona5, Harvard University6, Space Telescope Science Institute7, Massachusetts Institute of Technology8, Princeton University9, Tennessee State University10, École normale supérieure de Lyon11
TL;DR: In this paper, the water abundance in the atmosphere of the 2 MJup short-period exoplanet WASP-43b was determined based on thermal emission and transmission spectroscopy measurements obtained with the Hubble Space Telescope.
Abstract: The water abundance in a planetary atmosphere provides a key constraint on the planet’s primordial origins because water ice is expected to play an important role in the core accretion model of planet formation. However, the water content of the Solar System giant planets is not well known because water is sequestered in clouds deep in their atmospheres. By contrast, short-period exoplanets have such high temperatures that their atmospheres have water in the gas phase, making it possible to measure the water abundance for these objects. We present a precise determination of the water abundance in the atmosphere of the 2 MJup short-period exoplanet WASP-43b based on thermal emission and transmission spectroscopy measurements obtained with the Hubble Space Telescope. We nd the water content is consistent with the value expected in a solar composition gas at planetary temperatures (0:4 3:5 solar at 1 condence). The metallicity of WASP-43b’s atmosphere suggested by this result extends the trend observed in the Solar System of lower metal enrichment for higher planet masses. Subject headings: planets and satellites: atmospheres | planets and satellites: composition | planets and satellites: individual: WASP-43b
432 citations
Cites background from "Methane and its isotopologues on Sa..."
...Jupiter’s methane abundance is from the Galileo probe (Wong et al. 2004), while those of the other planets are from infrared spectroscopy (Fletcher et al. 2009; Karkoschka & Tomasko 2011; Sromovsky et al. 2011)....
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TL;DR: The Cassini-Huygens Probe Gas Chromatograph Mass Spectrometer (GCMS) determined the composition of the Titan atmosphere from ~140km altitude to the surface as mentioned in this paper.
Abstract: The Cassini-Huygens Probe Gas Chromatograph Mass Spectrometer (GCMS) determined the composition of the Titan atmosphere from ~140km altitude to the surface. After landing, it returned composition data of gases evaporated from the surface. Height profiles of molecular nitrogen (N2), methane (CH4) and molecular hydrogen (H2) were determined. Traces were detected on the surface of evaporating methane, ethane (C2H6), acetylene (C2H2), cyanogen (C2N2) and carbon dioxide (CO2). The methane data showed evidence that methane precipitation occurred recently. The methane mole fraction was (1.48+/-0.09) x 10(exp -2) in the lower stratosphere (139.8 km to 75.5 km) and (5.65+/-0.18) x 10(exp -2) near the surface (6.7 km to the surface). The molecular hydrogen mole fraction was (1.01+/-0.16) x 10(exp -3) in the atmosphere and (9.90+/-0.17) x 10(exp -4) on the surface. Isotope ratios were 167.7+/-0.6 for N-14/N-15 in molecular nitrogen, 91.1+/-1.4 for C-12/C-13 in methane and (1.35+/-0.30) x 10(exp -4) for D/H in molecular hydrogen. The mole fractions of Ar-36 and radiogenic Ar-40 are (2.1+/-0.8) x 10(exp -7) and (3.39 +/-0.12) x 10(exp -5) respectively. Ne-22 has been tentatively identified at a mole fraction of (2.8+/-2.1) x 10(exp -7) Krypton and xenon were below the detection threshold of 1 x 10(exp -8) mole fraction. Science data were not retrieved from the gas chromatograph subsystem as the abundance of the organic trace gases in the atmosphere and on the ground did not reach the detection threshold. Results previously published from the GCMS experiment are superseded by this publication.
403 citations
TL;DR: In this paper, a model of core-accretion planet formation in a one-dimensional disk was proposed, and it agrees well with our derived relation between mass and star mass.
Abstract: Exoplanet discoveries of recent years have provided a great deal of new data for studying the bulk compositions of giant planets. Here we identify 47 transiting giant planets ($20 M_\oplus 50$ $M_{\oplus}$) suggest significant amounts of heavy elements in H/He envelopes, rather than cores, such that metal-enriched giant planet atmospheres should be the rule. We also discuss a model of core-accretion planet formation in a one-dimensional disk and show that it agrees well with our derived relation between mass and $Z_{\rm planet}/Z_{\rm star}$.
233 citations
Cites background from "Methane and its isotopologues on Sa..."
...Spectroscopy of the Solar System’s giants points to enhancements in the mixing ratio of carbon (as seen in CH4) of ∼4, 10, 80, and 80, in Jupiter, Saturn, Uranus, and Neptune, respectively (Wong et al. 2004; Fletcher et al. 2009)....
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TL;DR: Titan is the only moon with a substantial atmosphere, the only other thick N2 atmosphere besides Earth's, the site of extraordinarily complex atmospheric chemistry that far surpasses any other solar system atmosphere, and the only solar system body with stable liquid currently on its surface as mentioned in this paper.
Abstract: Titan is the only moon with a substantial atmosphere, the only other thick N2 atmosphere besides Earth's, the site of extraordinarily complex atmospheric chemistry that far surpasses any other solar system atmosphere, and the only other solar system body with stable liquid currently on its surface. The connection between Titan's surface and atmosphere is also unique in our solar system; atmospheric chemistry produces materials that are deposited on the surface and subsequently altered by surface-atmosphere interactions such as aeolian and fluvial processes resulting in the formation of extensive dune fields and expansive lakes and seas. Titan's atmosphere is favorable for organic haze formation, which combined with the presence of some oxygen-bearing molecules indicates that Titan's atmosphere may produce molecules of prebiotic interest. The combination of organics and liquid, in the form of water in a subsurface ocean and methane/ethane in the surface lakes and seas, means that Titan may be the ideal place in the solar system to test ideas about habitability, prebiotic chemistry, and the ubiquity and diversity of life in the universe. The Cassini-Huygens mission to the Saturn system has provided a wealth of new information allowing for study of Titan as a complex system. Here I review our current understanding of Titan's atmosphere and climate forged from the powerful combination of Earth-based observations, remote sensing and in situ spacecraft measurements, laboratory experiments, and models. I conclude with some of our remaining unanswered questions as the incredible era of exploration with Cassini-Huygens comes to an end.
216 citations
TL;DR: Morley et al. as mentioned in this paper presented models of super Earths that include thick clouds and hazes and predicted their transmission, thermal emission, and reflected light spectra, and suggested a number of complementary observations to characterize this population of planets, including transmission spectra of hot (≳1000 K) targets, thermal emissions of warm targets using the James Webb Space Telescope, high spectral resolution (R∼105) observations of cloudy targets, and reflect light spectral observations of directly imaged cold targets.
Abstract: Author(s): Morley, CV; Fortney, JJ; Marley, MS; Zahnle, K; Line, M; Kempton, E; Lewis, N; Cahoy, K | Abstract: Planets larger than Earth and smaller than Neptune are some of the most numerous in the galaxy, but observational efforts to understand this population have proved challenging because optically thick clouds or hazes at high altitudes obscure molecular features. We present models of super Earths that include thick clouds and hazes and predict their transmission, thermal emission, and reflected light spectra. Very thick, lofted clouds of salts or sulfides in high metallicity (1000 solar) atmospheres create featureless transmission spectra in the near-infrared. Photochemical hazes with a range of particle sizes also create featureless transmission spectra at lower metallicities. Cloudy thermal emission spectra have muted features more like blackbodies, and hazy thermal emission spectra have emission features caused by an inversion layer at altitudes where the haze forms. Close analysis of reflected light from warm (∼400-800 K) planets can distinguish cloudy spectra, which have moderate albedos (0.05-0.20), from hazy models, which are very dark (0.0-0.03). Reflected light spectra of cold planets (∼200 K) accessible to a space-based visible light coronagraph will have high albedos and large molecular features that will allow them to be more easily characterized than the warmer transiting planets. We suggest a number of complementary observations to characterize this population of planets, including transmission spectra of hot (≳1000 K) targets, thermal emission spectra of warm targets using the James Webb Space Telescope, high spectral resolution (R∼105) observations of cloudy targets, and reflected light spectral observations of directly imaged cold targets. Despite the dearth of features observed in super Earth transmission spectra to date, different observations will provide rich diagnostics of their atmospheres.
209 citations
References
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TL;DR: In this article, new abundance tables have been compiled for C1 chondrites and the solar photosphere and corona, based on a critical review of the literature to mid-1988.
10,322 citations
Harvard University1, University of Reims Champagne-Ardenne2, College of William & Mary3, Old Dominion University4, University of Lisbon5, University of Burgundy6, California Institute of Technology7, Centre national de la recherche scientifique8, Université catholique de Louvain9, University of York10, University College London11, National Institute of Standards and Technology12, University of Waterloo13, National Center for Atmospheric Research14, University of Cologne15, Karlsruhe Institute of Technology16, Langley Research Center17
TL;DR: The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, added line-shape formalisms, and validity, and molecules, isotopologues, and perturbing gases have been added that address the issues of atmospheres beyond the Earth.
Abstract: This paper describes the contents of the 2016 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2012 and its updates during the intervening years. The HITRAN molecular absorption compilation is composed of five major components: the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, collision-induced absorption data, aerosol indices of refraction, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, added line-shape formalisms, and validity. Moreover, molecules, isotopologues, and perturbing gases have been added that address the issues of atmospheres beyond the Earth. Of considerable note, experimental IR cross-sections for almost 300 additional molecules important in different areas of atmospheric science have been added to the database. The compilation can be accessed through www.hitran.org. Most of the HITRAN data have now been cast into an underlying relational database structure that offers many advantages over the long-standing sequential text-based structure. The new structure empowers the user in many ways. It enables the incorporation of an extended set of fundamental parameters per transition, sophisticated line-shape formalisms, easy user-defined output formats, and very convenient searching, filtering, and plotting of data. A powerful application programming interface making use of structured query language (SQL) features for higher-level applications of HITRAN is also provided.
7,638 citations
TL;DR: In this article, solar photospheric and meteoritic CI chondrite abundance determinations for all elements are summarized and the best currently available photosphere abundances are selected, including the meteoritic and solar abundances of a few elements (e.g., noble gases, beryllium, boron, phosphorous, sulfur).
Abstract: Solar photospheric and meteoritic CI chondrite abundance determinations for all elements are summarized and the best currently available photospheric abundances are selected. The meteoritic and solar abundances of a few elements (e.g., noble gases, beryllium, boron, phosphorous, sulfur) are discussed in detail. The photospheric abundances give mass fractions of hydrogen (X ¼ 0:7491), helium (Y ¼ 0:2377), and heavy elements (Z ¼ 0:0133), leading to Z=X ¼ 0:0177, which is lower than the widely used Z=X ¼ 0:0245 from previous compilations. Recent results from standard solar models considering helium and heavy-element settling imply that photospheric abundances and mass fractions are not equal to protosolar abundances (representative of solar system abundances). Protosolar elemental and isotopic abundances are derived from photospheric abundances by considering settling effects. Derived protosolar mass fractions are X0 ¼ 0:7110, Y0 ¼ 0:2741, and Z0 ¼ 0:0149. The solar system and photospheric abundance tables are used to compute self-consistent sets of condensation temperatures for all elements. Subject headings: astrochemistry — meteors, meteoroids — solar system: formation — Sun: abundances — Sun: photosphere
4,305 citations
Book•
17 Jul 2000
TL;DR: This book treats the inverse problem of remote sounding comprehensively, and discusses a wide range of retrieval methods for extracting atmospheric parameters of interest from the quantities such as thermal emission that can be measured remotely.
Abstract: Remote sounding of the atmosphere has proved to be a fruitful method of obtaining global information about the atmospheres of the earth and planets. This book treats the inverse problem of remote sounding comprehensively, and discusses a wide range of retrieval methods for extracting atmospheric parameters of interest from the quantities such as thermal emission that can be measured remotely. Inverse theory is treated in depth from an estimation-theory point of view, but practical questions are also emphasized, for example designing observing systems to obtain the maximum quantity of information, efficient numerical implementation of algorithms for processing of large quantities of data, error analysis and approaches to the validation of the resulting retrievals, The book is targeted at both graduate students and working scientists.
4,052 citations