Detection of CS in Neptune’s atmosphere from ALMA observations

Moreno, R.; Lellouch, E.; Cavalié, T.; Moullet, Arielle

doi:10.1051/0004-6361/201731472

Cited by 27 publications

(53 citation statements)

References 41 publications

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“…Therefore, a reduced K in the 0.1-0.5 bar range is plausible, and is also in line with requirements from recent photochemical modelling (Moses et al, 2018). In this case the external CO source would also still be compatible with the giant comet impact proposed by (Lellouch et al, 2005) and supported by (Moreno et al, 2017). The silicate-rich Neptune suggested by Feuchtgruber et al (2013) would then be more compatible with the available observations than a water-rich Neptune.…”

Section: Neptune's Formation and Internal Structuresupporting

confidence: 84%

“…The large concentration of CO in Neptune's stratosphere led Lellouch et al (2005) to suggest that the source of Neptune's CO could be a large cometary impact that occurred ⇠200 years ago. This hypothesis is supported by the recent detection of CS by Moreno et al (2017), an impact product that was also detected after the Shoemaker-Levy 9 impact on Jupiter (Moreno et al, 2003). Moreno et al (2017) suggest a slightly larger 4 km diameter comet impacting ⇠1000 years ago.…”

Section: Phosphine (Phmentioning

confidence: 70%

“…This hypothesis is supported by the recent detection of CS by Moreno et al (2017), an impact product that was also detected after the Shoemaker-Levy 9 impact on Jupiter (Moreno et al, 2003). Moreno et al (2017) suggest a slightly larger 4 km diameter comet impacting ⇠1000 years ago.…”

Section: Phosphine (Phmentioning

confidence: 70%

See 2 more Smart Citations

Neptune’s carbon monoxide profile and phosphine upper limits from Herschel/SPIRE: Implications for interior structure and formation

Teanby

Irwin

Moses

2019

Icarus

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On Neptune, carbon monoxide and phosphine are disequilibrium species, and their abundance profiles can provide insights into interior processes and the external space environment. Here we use Herschel/SPIRE (Spectral and Photometric Imaging REceiver) observations from 14.9-51.5 cm 1 to obtain abundances from multiple CO and PH 3 spectral features. For CO, we find that nine CO bands can be simultaneously fitted using a step profile with a 0.22 ppm tropospheric abundance, a 1.03 ppm stratospheric abundance, and a step transition pressure of 0.11 bar near the tropopause. This is in broad agreement with previous studies. However, we also find that the CO spectral features could be fitted, to well within measurement errors, with a profile that contains no tropospheric CO for pressure levels deeper than 0.5 bar,

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Section: Neptune's Formation and Internal Structuresupporting

confidence: 84%

Section: Phosphine (Phmentioning

confidence: 70%

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Neptune’s carbon monoxide profile and phosphine upper limits from Herschel/SPIRE: Implications for interior structure and formation

Teanby

Irwin

Moses

2019

Icarus

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“…These species have presumably been formed during the comet impact by shock chemistry (Zahnle, 1996). Such events seem to be ubiquitous in the outer Solar System (see Cavalié et al 2009Cavalié et al , 2010 for Saturn, Cavalié et al 2014 for Uranus, and Lellouch et al 2005, Moreno et al 2017 for Neptune). Interestingly, tracing the evolution of the spatial distribution (both vertical and horizontal) of these rather long-lived species can provide us with an insight on the Jovian upper stratospheric dynamics.…”

Section: Introductionmentioning

confidence: 99%

Photochemistry, mixing and transport in Jupiter’s stratosphere constrained by Cassini

Hue

Hersant

Cavalié

et al. 2018

Icarus

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In this work, we aim at constraining the diffusive and advective transport processes in Jupiter's stratosphere, using Cassini/CIRS observations published by Nixon et al. (2007Nixon et al. ( , 2010. The Cassini-Huygens flyby of Jupiter on December 2000 provided the highest spatially resolved IR observations of Jupiter so far, with the CIRS instrument. The IR spectrum contains the fingerprints of several atmospheric constituents and allows probing the tropospheric and stratospheric composition. In particular, the abundances of C 2 H 2 and C 2 H 6 , the main compounds produced by methane photochemistry, can be retrieved as a function of latitude in the pressure range at which CIRS is sensitive to. CIRS observations suggest a very different meridional distribution for these two species. This is difficult to reconcile with their photochemical histories, which are thought to be tightly coupled to the methane photolysis. While the overall abundance of C 2 H 2 decreases with latitude, C 2 H 6 becomes more abundant at high latitudes. In this work, a new 2D (latitude-altitude) seasonal photochemical model of Jupiter is developed. The model is used to investigate whether the addition of stratospheric transport processes, such as meridional diffusion and advection, are able to explain the latitudinal behavior of C 2 H 2 and C 2 H 6 . We find that the C 2 H 2 observations are fairly well reproduced without meridional diffusion. Adding meridional diffusion to the model provides an improved agreement with the C 2 H 6 observations by flattening its meridional distribution, at the cost of a degradation of the fit to the C 2 H 2 distribution. However, meridional diffusion alone cannot produce the observed increase with latitude of the C 2 H 6 abundance. When adding 2D advective transport between roughly 30 mbar and 0.01 mbar, with upwelling winds at the equator and downwelling winds at high latitudes, we can, for the first time, reproduce the C 2 H 6 abundance increase with latitude. In parallel, the fit to the C 2 H 2 distribution is degraded. The strength of the advective winds needed to reproduce the C 2 H 6 abundances is particularly sensitive to the value of the meridional eddy diffusion coefficient. The coupled fate of these methane photolysis by-products suggests that an additional process is missing in the model. Ion-neutral chemistry was not accounted for in this work and might be a good candidate to solve this issue. 1

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“…The Herschel CO spectra have been modelled with a line-by-line radiative transfer model, which takes into account the spherical geometry and broadening due to planetary rotation, developed for Jupiter (Moreno et al 2001) and also used for Neptune (Moreno et al 2017). The CO opacity parameters were taken from the Jet Propulsion Laboratory molecular line catalogue (Pickett et al 1998); the collision-induced absorption opacity due to the main compounds of the Uranus atmosphere (H 2 -H 2 , H 2 -He, and H 2 -CH 4 ) adopt codes developed by Borysow et al (1985Borysow et al ( , 1988 and Borysow & Frommhold (1986).…”

Section: Radiative Transfer Modelmentioning

confidence: 99%

Analysis of the origin of water, carbon monoxide, and carbon dioxide in the Uranus atmosphere

Lara

Rodrigo

Moreno

et al. 2019

A&A

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Context. We present here an analysis of the potential sources of oxygen species in the Uranus atmosphere. Aims. Our aim is to explain the current measurements of H 2 O, CO, and CO 2 in the Uranus atmosphere, which would allow us to constrain the influx of oxygen-bearing species and its origin in this planet. Methods. We used a time-dependent photochemical model of the Uranus atmosphere to ascertain the origin of H 2 O, CO, and CO 2 . We thoroughly investigated the evolution of material delivered by a cometary impact, together with a combined source, i.e. cometary impact and a steady source of oxygen species from micrometeoroid ablation. Results. We find that an impactor in the size range ∼1.2-3.5 km hitting the planet between 450 and 822 yr ago could have delivered the CO currently seen in the Uranus stratosphere. Given the current set of observations, an oxygen-bearing species supply from ice grain ablation cannot be ruled out. Our study also indicates that a cometary impact cannot be the only source for rendering the observed abundances of H 2 O and CO 2 . The scenarios in which CO originates by a cometary impact and H 2 O and CO 2 result from ice grain sublimation can explain both the space telescope and ground-based data for H 2 O, CO, and CO 2 . Similarly, a steady influx of water, carbon monoxide, and carbon dioxide, and a cometary impact delivering carbon monoxide give rise to abundances matching the observations. The time evolution of HCN also delivered by a cometary impact (as 1% of the CO in mass), when discarding chemical recycling of HCN once it is lost by photolysis and condensation, produces a very low stratospheric abundance which could be likely non-detectable. Consideration of N 2 -initiated chemistry could represent a source of HCN allowing for a likely observable stratospheric mixing ratio. Conclusions. Our modelling strongly indicates that water in the Uranus atmosphere likely originates from micrometeroid ablation, whereas its cometary origin can be discarded with a very high level of confidence. Also, we cannot firmly constrain the origin of the detected carbon monoxide on Uranus as a cometary impact, ice grain ablation, or a combined source due to both processes can give rise to the atmospheric mixing ratio measured with the Herschel Space Observatory. To establish the origin of oxygen species in the Uranus atmosphere, observations have to allow the retrieval of vertical profiles or H 2 O, CO, and CO 2 . Measurements in narrow pressure ranges, i.e. basically one pressure level, can be reproduced by different models because it is not possible to break this degeneracy about these three oxygen species in the Uranian atmosphere.

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Detection of CS in Neptune’s atmosphere from ALMA observations

Cited by 27 publications

References 41 publications

Neptune’s carbon monoxide profile and phosphine upper limits from Herschel/SPIRE: Implications for interior structure and formation

Neptune’s carbon monoxide profile and phosphine upper limits from Herschel/SPIRE: Implications for interior structure and formation

Photochemistry, mixing and transport in Jupiter’s stratosphere constrained by Cassini

Analysis of the origin of water, carbon monoxide, and carbon dioxide in the Uranus atmosphere

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