Native-resolution retrievals on 0.97-5.27 micron JWST spectra of VHS 1256 b find a ~79% cloud deck, solar-like metallicity and C/O, and depleted 18O in a partially cloudy disequilibrium atmosphere.
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The effects of snowlines on C/O in planetary atmospheres
15 Pith papers cite this work. Polarity classification is still indexing.
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abstract
The C/O ratio is predicted to regulate the atmospheric chemistry in hot Jupiters. Recent observations suggest that some exo-planets, e.g. Wasp 12- b, have atmospheric C/O ratios substantially different from the solar value of 0.54. In this paper we present a mechanism that can produce such atmospheric deviations from the stellar C/O ratio. In protoplanetary disks, different snowlines of oxygen- and carbon-rich ices, especially water and carbon monoxide, will result in systematic variations in the C/O ratio both in the gas and in the condensed phase. In particular, between the H2O and CO snowlines most oxygen is present in icy grains - the building blocks of planetary cores in the core accretion model - while most carbon remains in the gas-phase. This region is coincidental with the giant-planet forming zone for a range of observed protoplanetary disks. Based on standard core accretion models of planet formation, gas giants that sweep up most of their atmospheres from disk gas outside of the water snowline will have C/O?1, while atmospheres significantly contaminated by evaporating planetesimals will have stellar or sub-stellar C/O when formed at the same disk radius. The overall metallicity will also depend on the atmosphere formation mechanism, and exoplanetary atmospheric compositions may therefore provide constraints on where and how a specific planet formed.
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2D disc simulations with vertical volatile transport produce stable CO snow surface equilibria and eliminate limit-cycle behavior seen in 1D models.
Older Upper Scorpius disks show reduced molecular emission and hints of higher inner-gas C/O ratios than young disks, indicating chemical evolution consistent with pebble drift.
Phase-resolved high-resolution spectroscopy of CoRoT-2b measures sub-synchronous rotation at 2.6-sigma significance, consistent with its western hotspot offset.
GRAVITY+ observations yield a 12CO/13CO ratio of 91^{+24}_{-17} in β Pictoris b consistent with solar/ISM values and a tentative 1.4% atmospheric variability amplitude.
Planets with realistic dense cores survive close star encounters without total disruption, allowing more to circularize into hot Jupiters or be ejected after mass loss.
TOI-1533 is confirmed as a rare compact system hosting an inner sub-Neptune and an outer hot super-Neptune-mass giant with nearly equal masses and very different radii.
Panchromatic JWST spectrum of WASP-121 b detects SiO and measures refractory-to-volatile ratios 3x stellar, consistent with mixed solid-gas accretion or migration with continued solid accretion.
First velocity-resolved [O I] 63/145 um maps of the Orion BN/KL outflow show broad components from dense warm postshock gas, with line ratios matching 30-40 km/s dissociative J-shocks illuminated by external UV, yielding [O I] luminosity 86.5 L_sun and mass-loss rate ~9e-3 M_sun/yr.
Two extremely low-density Jupiter-sized planets on long-period orbits around TOI-791 were confirmed via ground-based photometry and TTV-derived masses.
DFT-derived binding energy distributions for methanol and photolysis products on ASW ice, integrated into astrochemical models, demonstrate sensitivity of radical abundances to BE calculation methods.
Updated DALI models reproduce observed C2H2 fluxes with solar C/O and find the C2H2/H2O flux ratio sensitive to elemental abundances and small-grain abundance in planet-forming disk regions.
Observational study of 290 exoplanet-host stars finds higher C, O, S, Fe, Ni abundances in giant-planet hosts than small-planet hosts, with C/O ratios, hot/warm differences, and mass correlations that vary by subpopulation.
Retrievals on six isolated brown dwarfs yield near-solar C/O (0.51-0.63), metallicities, and 12C/13C ratios (91-155) supporting molecular cloud fragmentation origin.
The paper identifies three key science cases that will require Hubble's short-wavelength capabilities for exoplanet atmosphere studies into the 2030s.
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The GAPS programme at TNG: LXXVI. TOI-1533: a compact system hosting a super-Neptune-mass pair with disparate radii
TOI-1533 is confirmed as a rare compact system hosting an inner sub-Neptune and an outer hot super-Neptune-mass giant with nearly equal masses and very different radii.