Thermal Structure and Para Hydrogen Fraction on the Outer Planets fromVoyagerIRIS Measurements

Conrath, B. J.; Gierasch, P. J.; Ustinov, E. A.

doi:10.1006/icar.1998.6000

Cited by 154 publications

(249 citation statements)

References 19 publications

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“…1 are very similar to the disk-averaged profiles we used previously and, in the upper tropospheres and lower stratospheres, consistent with the equatorial structures determined by Flasar et al (1987), Conrath et al (1991Conrath et al ( , 1998, from Voyager IRIS spectra. For Uranus, the profile (from Lindal 1992) may differ from the modeling of Marley & McKay (1999), since our present study is concerned essentially with the mean tropospheric profile on this planet.…”

Section: Atmospheric Models Of Uranus and Neptunesupporting

confidence: 70%

“…The nominal tropospheric thermal profile is found to be 2 K colder than our initial model obtained from the Voyager 2 occultation profile (Lindal 1992). In the region of the tropopause, it is slightly colder than the mean-average equatorial structure observed by Conrath et al (1998) from Voyager IRIS spectra. Since our observations, and our modeling results, are averages over the whole planetary disk, these temperature discrepancies are not likely to be in significant conflict with the Voyager results.…”

Section: Discussionmentioning

confidence: 74%

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Improved constraints on Neptune's atmosphere from submillimetre-wavelength observations

Marten¹,

Matthews

Owen

et al. 2005

A&A

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Abstract. We describe observations of Neptune carried out using the James Clerk Maxwell Telescope (Mauna Kea, Hawaii) during September 1998. High-quality data for the sub-mm-wavelength rotational transitions of HCN (J = 4−3) and CO (J = 3−2 and 4−3) were obtained, and we use the data to make improved determinations of the abundances of these trace species and the temperature profile of Neptune's atmosphere.

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Section: Atmospheric Models Of Uranus and Neptunesupporting

confidence: 70%

Section: Discussionmentioning

confidence: 74%

Improved constraints on Neptune's atmosphere from submillimetre-wavelength observations

Marten¹,

Matthews

Owen

et al. 2005

A&A

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“…We do not use the flux at the first, deepest level as a constraint because the variation of the Planck function at deeper levels is fixed arbitrarily in the model to that of the first layer. To solve this system of n p−1 equations, we use a constrained linear inversion method described in Vinatier et al (2007) and based on Conrath et al (1998). The algorithm minimizes the quadratic difference (χ 2 ) between desired (σT 4 eff ) and calculated fluxes with the additional constraint that the solution temperature profile lies close to the reference profile.…”

Section: Discussionmentioning

confidence: 99%

Interpreting the photometry and spectroscopy of directly imaged planets: a new atmospheric model applied toβPictoris b and SPHERE observations

Baudino

Bézard

Boccaletti

et al. 2015

A&A

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Context. Since the end of 2013 a new generation of instruments optimized to image young giant planets around nearby stars directly is becoming available on 8-m class telescopes, both at Very Large Telescope and Gemini in the southern hemisphere. Beyond the achievement of high contrast and the discovery capability, these instruments are designed to obtain photometric and spectral information to characterize the atmospheres of these planets. Aims. We aim to interpret future photometric and spectral measurements from these instruments, in terms of physical parameters of the planets, with an atmospheric model using a minimal number of assumptions and parameters. Methods. We developed the Exoplanet Radiative-convective Equilibrium Model (Exo-REM) to analyze the photometric and spectroscopic data of directly imaged planets. The input parameters are a planet's surface gravity (g), effective temperature (T eff ), and elemental composition. The model predicts the equilibrium temperature profile and mixing ratio profiles of the most important gases. Opacity sources include the H 2 -He collision-induced absorption and molecular lines from eight compounds (including CH 4 updated with the Exomol line list). Absorption by iron and silicate cloud particles is added above the expected condensation levels with a fixed scale height and a given optical depth at some reference wavelength. Scattering was not included at this stage.Results. We applied Exo-REM to photometric and spectral observations of the planet β Pictoris b obtained in a series of near-infrared filters. We derived T eff = 1550 ± 150 K, log(g) = 3.5 ± 1, and radius R = 1.76 ± 0.24 R Jup (2σ error bars from photometric measurements). These values are comparable to those found in the literature, although with more conservative error bars, consistent with the model accuracy. We were able to reproduce, within error bars, the J-and H-band spectra of β Pictoris b. We finally investigated the precision to which the above parameters can be constrained from SPHERE measurements using different sets of near-infrared filters as well as low-resolution spectroscopy.

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“…For pressures greater than 1 mbar the Voyager/RSS results stand out as being cooler (minimum of 49 K, Lindal et al 1990) than the others, whereas subsequent analyses of remote sensing data from ISO (Bézard et al 1998;Fouchet et al 2003;Burgdorf et al 2003) and the Voyager infrared radiometer and spectrometer (IRIS, Conrath et al 1998) have suggested warmer tropopause temperatures of approximately 56 K, dropping to 50-52 K at mid-latitudes.…”

Section: Globally-averaged Temperaturesmentioning

confidence: 99%

“…AKARI spectroscopy of both CH 4 and the higher-order hydrocarbons will be used to determine Neptune's stratospheric temperature and composition. The cold atmospheric temperatures yield an extremely low-power thermal emission spectrum which requires high sensitivity to measure accurately, and AKARI results will be compared to previous derivations of Neptune's thermal structure from the Voyager radio science investigation (RSS, Lindal et al 1990), infrared spectrometer (IRIS, Conrath et al 1998) and the Infrared Space Observatory (ISO, Feuchtgruber et al 1999;Fouchet et al 2003;Burgdorf et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Neptune's atmospheric composition from AKARI infrared spectroscopy

Fletcher

Drossart

Burgdorf

et al. 2010

A&A

115

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Aims. Disk-averaged infrared spectra of Neptune between 1.8 and 13 μm, obtained by the AKARI infrared camera (IRC) in May 2007, have been analysed to (a) determine the globally-averaged stratospheric temperature structure; (b) derive the abundances of stratospheric hydrocarbons; and (c) detect fluorescent emission from CO at 4.7 μm. Methods. Mid-infrared spectra (SG1 and SG2 channels of AKARI/IRC), with spectral resolutions of 47 and 34 respectively, were modelled using a line-by-line radiative transfer code to determine the temperature structure between 1-1000 μbar and the abundances of CH 4 , CH 3 D and higher-order hydrocarbons. A full non-LTE radiative model was then used to determine the best fitting CO profile to reproduce the fluorescent emission observed at 4.7 μm in the NG channel (with a spectral resolution of 135). Results. The globally-averaged stratospheric temperature structure is quasi-isothermal between 1-1000 μbar, which suggests little variation in global stratospheric conditions since studies by the Infrared Space Observatory a decade earlier. The derived CH 4 mole fraction of (9.0 ± 3.0) × 10 −4 at 50 mbar, decreasing to (0.9 ± 0.3) × 10 −4 at 1 μbar, is larger than that expected if the tropopause at 56 K acts as an efficient cold trap, but consistent with the hypothesis that CH 4 leaking through the warm south polar tropopause (62-66 K) is globally redistributed by stratospheric motion. The ratio of D/H in CH 4 of 3.0 ± 1.0 × 10 −4 supports the conclusion that Neptune is enriched in deuterium relative to the other giant planets. We determine a mole fraction of ethane of (8.5 ± 2.1) × 10 −7 at 0.3 mbar, consistent with previous studies, and a mole fraction of ethylene of 5.0 +1.8 −2.1 × 10 −7 at 2.8 μbar. An emission peak at 4.7 μm is interpreted as a fluorescent emission of CO, and requires a vertical distribution with both external and internal sources of CO. Finally, comparisons to previous L-band studies indicate significant variability of Neptune's flux densities in the 3.5-4.1 μm range, related to changes in solar energy deposition.

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Thermal Structure and Para Hydrogen Fraction on the Outer Planets fromVoyagerIRIS Measurements

Cited by 154 publications

References 19 publications

Improved constraints on Neptune's atmosphere from submillimetre-wavelength observations

Improved constraints on Neptune's atmosphere from submillimetre-wavelength observations

Interpreting the photometry and spectroscopy of directly imaged planets: a new atmospheric model applied toβPictoris b and SPHERE observations

Neptune's atmospheric composition from AKARI infrared spectroscopy

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