Excess C/O and C/H in Outer Protoplanetary Disk Gas

Öberg, Karin I.; Bergin, Edwin A.

doi:10.3847/2041-8205/831/2/l19

Cited by 103 publications

(106 citation statements)

References 51 publications

(58 reference statements)

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“…In general, planets that form within the same PPD can have very different volatile element budgets (e.g., Öberg & Bergin 2016) but have generally similar budgets in relative refractory elements (e.g., Elser et al 2012;Bond et al 2010;Thiabaud et al 2014;Sotin et al 2007). The reason is that the disc region where condensation temperatures of different volatile compounds (< 200K) are reached is very extended (semi-major distances a > 1AU).…”

Section: Introductionmentioning

confidence: 99%

A new class of Super-Earths formed from high-temperature condensates: HD219134 b, 55 Cnc e, WASP-47 e

Dorn

Harrison

Bonsor

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We hypothesise that differences in the temperatures at which the rocky material condensed out of the nebula gas can lead to differences in the composition of key rocky species (e.g., Fe, Mg, Si, Ca, Al, Na) and thus planet bulk density. Such differences in the observed bulk density of planets may occur as a function of radial location and time of planet formation. In this work we show that the predicted differences are on the cusp of being detectable with current instrumentation. In fact, for HD 219134, the 10 % lower bulk density of planet b compared to planet c could be explained by enhancements in Ca, Al rich minerals. However, we also show that the 11 % uncertainties on the individual bulk densities are not sufficiently accurate to exclude the absence of a density difference as well as differences in volatile layers. Besides HD 219134 b, we demonstrate that 55 Cnc e and WASP-47 e are similar candidates of a new Super-Earth class that have no core and are rich in Ca and Al minerals which are among the first solids that condense from a cooling proto-planetary disc. Planets of this class have densities 10-20% lower than Earth-like compositions and may have very different interior dynamics, outgassing histories and magnetic fields compared to the majority of Super-Earths.

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Section: Introductionmentioning

confidence: 99%

A new class of Super-Earths formed from high-temperature condensates: HD219134 b, 55 Cnc e, WASP-47 e

Dorn

Harrison

Bonsor

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…The way how CO freezes, namely in what structure (whether trapped in a water-rich matrix or in pure CO layers), affects the temperature at which it returns into the gas-phase. In turn, this has important consequences on a variety of situ-ations; for example, on the molecular deuteration of water and trace species (Ceccarelli et al 2014), on the formation of methanol and more complex organic molecules in the protostellar phase (Garrod & Herbst 2006), or on the composition of the gaseous giant planets (Oberg & Bergin 2016;Madhusudhan et al 2017). Therefore, understanding the molecular structure of the interstellar solid CO is of great importance.…”

Section: Introductionmentioning

confidence: 99%

IR spectral fingerprint of carbon monoxide in interstellar water–ice models

Zamirri

Casassa

Rimola

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Carbon monoxide (CO) is the second most abundant molecule in the gas-phase of the interstellar medium. In dense molecular clouds, it is also present in the solid-phase as a constituent of the mixed water-dominated ices covering dust grains. Its presence in the solid-phase is inferred from its infrared (IR) signals. In experimental observations of solid CO/water mixed samples, its IR frequency splits into two components, giving rise to a blue-and a redshifted band. However, in astronomical observations, the former has never been observed. Several attempts have been carried out to explain this peculiar behaviour, but the question still remains open. In this work, we resorted to pure quantum mechanical simulations in order to shed some light on this problem. We adopted different periodic models simulating the CO/H 2 O ice system, such as single and multiple CO adsorption on water ice surfaces, CO entrapped into water cages and proper CO:H 2 O mixed ices. We also simulated pure solid CO. The detailed analysis of our data revealed how the quadrupolar character of CO and the dispersive forces with water ice determine the energetic of the CO/H 2 O ice interaction, as well as the CO spectroscopic behaviour. Our data suggest that the blueshifted peak can be assigned to CO interacting via the C atom with dangling H atoms of the water ice, while the redshifted one can actually be the result of CO involved in different reciprocal interactions with the water matrix. We also provide a possible explanation for the lack of the blueshifted peak in astronomical spectra. Our aim is not to provide a full account of the various interstellar ices, but rather to elucidate the sensitivity of the CO spectral features to different water ice environments.

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“…The observational evidence of C/O > 1 planets is debated (Madhusudhan et al 2011b;Crossfield et al 2012;Swain et al 2013;Stevenson et al 2014;Line et al 2014;Kreidberg et al 2015;Benneke 2015) and there have been numerous studies trying to theoretically assess whether the formation of C/O > 1 or C/O → 1 planets is possible (Öberg et al 2011;Ali-Dib et al 2014;Thiabaud et al 2014Thiabaud et al , 2015Helling et al 2014;Marboeuf et al 2014b,a;Madhusudhan et al 2014aMadhusudhan et al , 2016Öberg & Bergin 2016), while one of the most recent works on this topic indicates that hot Jupiters (which usually have masses 3M ) and planets of lower mass may never have C/O > 1 .…”

Section: C/omentioning

confidence: 99%

“…The reason for this is the clouds' decreased optical depth when not being viewed in transit geometry (Fortney 2005). Moreover, the analysis of the resulting atmospheric composition and abundance ratios may allow placement of constraints on planets' formation locations, although the exact interpretation of the atmospheric abundances depends on the assumptions and the degree of complexity of the model being used to describe the planet formation and evolution (Öberg et al 2011;Ali-Dib et al 2014;Thiabaud et al 2014;Helling et al 2014;Marboeuf et al 2014b,a;Madhusudhan et al 2014aMadhusudhan et al , 2016Mordasini et al 2016;Öberg & Bergin 2016;Cridland et al 2016).…”

Section: While the Question Of The Origins Of Clouds Is Fundamentalmentioning

confidence: 99%

Observing transiting planets with JWST

Mollière

Boekel

Bouwman

et al. 2017

A&A

176

250

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Context. The James Webb Space Telescope will enable astronomers to obtain exoplanet spectra of unprecedented precision. The MIRI instrument especially may shed light on the nature of the cloud particles obscuring planetary transmission spectra in the optical and near-infrared. Aims. We provide self-consistent atmospheric models and synthetic JWST observations for prime exoplanet targets in order to identify spectral regions of interest and estimate the number of transits needed to distinguish between model setups. Methods. We select targets that span a wide range of planetary temperatures and surface gravities, ranging from super-Earths to giant planets, that have a high expected signal-to-noise ratio. For all targets, we vary the enrichment, C/O ratio, presence of optical absorbers (TiO/VO), and cloud treatment. We calculate atmospheric structures, emission, and transmission spectra for all targets and use a radiometric model to obtain simulated observations. Further, we analyze JWST's ability to distinguish between various scenarios. Results. We find that in very cloudy planets, such as GJ 1214b, less than ten transits with NIRSpec may be enough to reveal molecular features. Furthermore, the presence of small silicate grains in atmospheres of hot Jupiters may be detectable with a single JWST MIRI transit. For a more detailed characterization of such particles less than ten transits are necessary. Finally, we find that some of the hottest hot Jupiters are well fitted by models which neglect the redistribution of the insolation and harbor inversions, and that 1-4 eclipse measurements with NIRSpec are needed to distinguish between the inversion models.Conclusions. Wet thus demonstrate the capabilities of JWST for solving some of the most intriguing puzzles in current exoplanet atmospheric research. Further, by publishing all models calculated for this study we enable the community to carry out similar studies, as well as retrieval analyses for all planets included in our target list.

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Excess C/O and C/H in Outer Protoplanetary Disk Gas

Cited by 103 publications

References 51 publications

A new class of Super-Earths formed from high-temperature condensates: HD219134 b, 55 Cnc e, WASP-47 e

A new class of Super-Earths formed from high-temperature condensates: HD219134 b, 55 Cnc e, WASP-47 e

IR spectral fingerprint of carbon monoxide in interstellar water–ice models

Observing transiting planets with JWST

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