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  1. Article ; Online: Isotopic evidence of long-lived volcanism on Io.

    de Kleer, Katherine / Hughes, Ery C / Nimmo, Francis / Eiler, John / Hofmann, Amy E / Luszcz-Cook, Statia / Mandt, Kathy

    Science (New York, N.Y.)

    2024  Volume 384, Issue 6696, Page(s) 682–687

    Abstract: Jupiter's moon Io hosts extensive volcanism, driven by tidal heating. The isotopic composition of Io's inventory of volatile chemical elements, including sulfur and chlorine, reflects its outgassing and mass-loss history and thus records information ... ...

    Abstract Jupiter's moon Io hosts extensive volcanism, driven by tidal heating. The isotopic composition of Io's inventory of volatile chemical elements, including sulfur and chlorine, reflects its outgassing and mass-loss history and thus records information about its evolution. We used submillimeter observations of Io's atmosphere to measure sulfur isotopes in gaseous sulfur dioxide and sulfur monoxide, and chlorine isotopes in gaseous sodium chloride and potassium chloride. We find
    Language English
    Publishing date 2024-04-18
    Publishing country United States
    Document type Journal Article
    ZDB-ID 128410-1
    ISSN 1095-9203 ; 0036-8075
    ISSN (online) 1095-9203
    ISSN 0036-8075
    DOI 10.1126/science.adj0625
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  2. Book ; Online: Neptune's Spatial Brightness Temperature Variations from the VLA and ALMA

    Tollefson, Joshua / de Pater, Imke / Molter, Edward M. / Sault, Robert J. / Butler, Bryan J. / Luszcz-Cook, Statia / DeBoer, David

    2021  

    Abstract: We present spatially resolved ($0.1'' - 1.0''$) radio maps of Neptune taken from the Very Large Array and Atacama Large Submillimeter/Millimeter Array between $2015-2017$. Combined, these observations probe from just below the main methane cloud deck at $ ...

    Abstract We present spatially resolved ($0.1'' - 1.0''$) radio maps of Neptune taken from the Very Large Array and Atacama Large Submillimeter/Millimeter Array between $2015-2017$. Combined, these observations probe from just below the main methane cloud deck at $\sim 1$ bar down to the NH$_4$SH cloud at $\sim50$ bar. Prominent latitudinal variations in the brightness temperature are seen across the disk. Depending on wavelength, the south polar region is $5-40$ K brighter than the mid-latitudes and northern equatorial region. We use radiative transfer modeling coupled to Markov Chain Monte Carlo methods to retrieve H$_2$S, NH$_3$, and CH$_4$ abundance profiles across the disk, though only strong constraints can be made for H$_2$S. Below all cloud formation, the data are well fit by $53.8^{+18.9}_{-13.4}\times$ and $3.9^{+2.1}_{-3.1}\times$ protosolar enrichment in the H$_2$S and NH$_3$ abundances, respectively, assuming a dry adiabat. Models in which the radio-cold mid-latitudes and northern equatorial region are supersaturated in H$_2$S are statistically favored over models following strict thermochemical equilibrium. H$_2$S is more abundant at the equatorial region than at the poles, indicative of strong, persistent global circulation. Our results imply that Neptune's sulfur-to-nitrogen ratio exceeds unity as H$_2$S is more abundant than NH$_3$ in every retrieval. The absence of NH$_3$ above 50 bar can be explained either by partial dissolution of NH$_3$ in an ionic ocean at GPa pressures or by a planet formation scenario in which hydrated clathrates preferentially delivered sulfur rather than nitrogen onto planetesimals, or a combination of these hypotheses.
    Keywords Astrophysics - Earth and Planetary Astrophysics
    Subject code 520 ; 551
    Publishing date 2021-04-13
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Book ; Online: Neptune's Latitudinal Variations as Viewed with ALMA

    Tollefson, Joshua / de Pater, Imke / Luszcz-Cook, Statia / DeBoer, David

    2019  

    Abstract: We present spatially resolved millimeter maps of Neptune between 95 and 242 GHz taken with the Atacama Large Millimeter/submillimeter Array (ALMA) in $2016-2017$. The millimeter weighting functions peak between 1 and 10 bar on Neptune, lying in between ... ...

    Abstract We present spatially resolved millimeter maps of Neptune between 95 and 242 GHz taken with the Atacama Large Millimeter/submillimeter Array (ALMA) in $2016-2017$. The millimeter weighting functions peak between 1 and 10 bar on Neptune, lying in between the altitudes probed at visible/infrared and centimeter wavelengths. Thus, these observations provide important constraints on the atmospheric structure and dynamics of Neptune. We identify seven well-resolved latitudinal bands of discrete brightness temperature variations, on the order of $0.5-3$K in all three observed ALMA spectral bands. We model Neptune's brightness temperature using the radiative transfer code Radio-BEAR and compare how various H$_2$S, CH$_4$, and \textit{ortho/para} H$_2$ abundance profiles can fit the observed temperature variations across the disk. We find that observed variations in brightness temperature with latitude can be explained by variations in the H$_2$S profile that range from sub- to super-saturations at altitudes above the 10-bar pressure level, while variations in CH$_4$ improve the quality of fit near the equator. At the south polar cap, our best fit model has a depleted deep atmospheric abundance of H$_2$S from 30 to only 1.5 times the protosolar value, while simultaneously depleting the CH$_4$ abundance. This pattern of enhancement and depletion of condensable species is consistent with a global circulation structure where enriched air rises at the mid-latitudes ($32^{\circ}-12^{\circ}$S) and north of the equator ($2^{\circ}-20^{\circ}$N), and dry air descends at the poles ($90^{\circ}-66^{\circ}$S) and just south of the equator ($12^{\circ}$S$-2^{\circ}$N). Our analysis finds more complex structure near the equator than accounted for in previous circulation models.

    Comment: 21 pages, 17 Figures, accepted into the Astronomical Journal May, 2019
    Keywords Astrophysics - Earth and Planetary Astrophysics
    Subject code 551
    Publishing date 2019-05-08
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Book ; Online: Dispersion in Neptune's Zonal Wind Velocities from NIR Keck AO Observations in July 2009

    Fitzpatrick, Patrick J. / de Pater, Imke / Luszcz-Cook, Statia / Wong, Michael H. / Hammel, Heidi B.

    2013  

    Abstract: We report observations of Neptune made in H-(1.4-1.8 {\mu}m) and K'-(2.0-2.4 {\mu}m) bands on 14 and 16 July 2009 from the 10-m W.M. Keck II Telescope using the near-infrared camera NIRC2 coupled to the Adaptive Optics (AO) system. We track the positions ...

    Abstract We report observations of Neptune made in H-(1.4-1.8 {\mu}m) and K'-(2.0-2.4 {\mu}m) bands on 14 and 16 July 2009 from the 10-m W.M. Keck II Telescope using the near-infrared camera NIRC2 coupled to the Adaptive Optics (AO) system. We track the positions of 54 bright atmospheric features over a few hours to derive their zonal and latitudinal velocities, and perform radiative transfer modeling to measure the cloud-top pressures of 50 features seen simultaneously in both bands. We observe one South Polar Feature (SPF) on 14 July and three SPFs on 16 July at ~65 deg S. The SPFs observed on both nights are different features, consistent with the high variability of Neptune's storms. There is significant dispersion in Neptune's zonal wind velocities about the smooth Voyager wind profile fit of Sromovsky et al., Icarus 105, 140 (1993), much greater than the upper limit we expect from vertical wind shear, with the largest dispersion seen at equatorial and southern mid-latitudes. Comparison of feature pressures vs. residuals in zonal velocity from the smooth Voyager wind profile also directly reveals the dominance of mechanisms over vertical wind shear in causing dispersion in the zonal winds. Vertical wind shear is not the primary cause of the difference in dispersion and deviation in zonal velocities between features tracked in H-band on 14 July and those tracked in K'-band on 16 July. Dispersion in the zonal velocities of features tracked over these short time periods is dominated by one or more mechanisms, other than vertical wind shear, that can cause changes in the dispersion and deviation in the zonal velocities on timescales of hours to days.

    Comment: 31 pages, 13 Figures, 3 Tables, Accepted for publication in Astrophysics and Space Science
    Keywords Astrophysics - Earth and Planetary Astrophysics
    Subject code 551
    Publishing date 2013-12-10
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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