Latitudinal variations in methane abundance, aerosol opacity and aerosol scattering efficiency in Neptune's atmosphere determined from VLT/MUSE
Journal of Geophysical Research: Planets American Geophysical Union 128:11 (2023) e2023JE007980
Abstract:
Spectral observations of Neptune made in 2019 with the MUSE instrument at the Very Large Telescope in Chile have been analysed to determine the spatial variation of aerosol scattering properties and methane abundance in Neptune’s atmosphere. The darkening of the South Polar Wave (SPW) at ∼ 60◦S, and dark spots such as the Voyager 2 Great Dark Spot is concluded to be due to a spectrally-dependent darkening (λ < 650nm) of particles in a deep aerosol layer at ∼ 5 bar and presumed to be composed of a mixture of ~ 650 nm, with bright zones latitudinally separated by ∼ 25◦ . This feature, similar to the spectral characteristics of a discrete deep bright spot DBS-2019 found in our data, is found to be consistent with a brightening of the particles in the same ∼5-bar aerosol layer at λ > 650 nm. We find the properties of an overlying methane/haze aerosol layer at ∼ 2 bar are, to first-order, invariant with latitude, while variations in the opacity of an upper tropospheric haze layer reproduce the observed reflectivity at methane-absorbing wavelengths, with higher abundances found at the equator and also in a narrow ‘zone’ at 80◦S. Finally, we find the mean abundance of methane below its condensation level to be 6-7% at the equator reducing to ∼3% south of ∼25◦S, although the absolute abundances are model dependent.Methane throughout the atmosphere of the warm exoplanet WASP-80b.
Nature 623:7988 (2023) 709-712
Abstract:
The abundances of main carbon- and oxygen-bearing gases in the atmospheres of giant exoplanets provide insights into atmospheric chemistry and planet formation processes1,2. Thermochemistry suggests that methane (CH4) should be the dominant carbon-bearing species below about 1,000 K over a range of plausible atmospheric compositions3; this is the case for the solar system planets4 and has been confirmed in the atmospheres of brown dwarfs and self-luminous, directly imaged exoplanets5. However, CH4 has not yet been definitively detected with space-based spectroscopy in the atmosphere of a transiting exoplanet6-11, but a few detections have been made with ground-based, high-resolution transit spectroscopy12,13 including a tentative detection for WASP-80b (ref. 14). Here we report transmission and emission spectra spanning 2.4-4.0 μm of the 825 K warm Jupiter WASP-80b taken with the NIRCam instrument of the JWST, both of which show strong evidence of CH4 at greater than 6σ significance. The derived CH4 abundances from both viewing geometries are consistent with each other and with solar to sub-solar C/O and around five times solar metallicity, which is consistent with theoretical predictions15-17.Latitudinal variations in methane abundance, aerosol opacity and aerosol scattering efficiency in Neptune's atmosphere determined from VLT/MUSE
(2023)
INFUSE: preflight performance of a rocket-borne FUV integral field spectrograph
Proceedings of SPIE--the International Society for Optical Engineering SPIE, the international society for optics and photonics 12678 (2023) 1267808-1267808-12
The temporal brightening of Uranus’ northern polar hood from HST/WFC3 and HST/STIs observations
Journal of Geophysical Research: Planets Wiley 128:10 (2023) e2023JE007904