The Meridian S02E01 : The James Webb Space Telescope & an unexpected boat ride

In this first episode of the second season Nic and Rebecca invite Ori Fox to the podcast to discuss the newly launched JWST. Ori is an instrument scientist at the pace Telescope Science Institute (STSI) working on the Mid-Infrared Instrument (MIRI) which is one of four instruments on the James Webb Space Telescope. In this second season of the Meridian we are also bringing you some field reporting from the Nordic Optical Telescope on La Palma, where a team of astronomers are trying to catch an ultra-hot Jupiter-sized exoplanet

The Meridian S02E05 : New insights into Venus' past & an erupting volcano

Michael Way works at the NASA Goddard Institute for Space Studies where he is modeling planetary atmospheres, with a special interest for Venus and its history. He was visiting Lund Observatory to give a talk at the Källén Seminars for Young Astronomers recently, and we invited him onto the podcast to ask him if there is a chance that Venus has ever been habitable (Spoiler: the answer is 'yes'). In this second season of the Meridian we are also bringing you some field reporting from the Nordic Optical Telescope on La Palma, where a team of astronomers are trying to catch an ultra-hot Jupiter-sized exoplanet

The Meridian S02E07 : Ancient solar storms & observing reflections

In this last episode of the second season Nic and Rebecca get a visitor from the Department of Geology. One does not always use telescopes to study the stars. Chiara Paleari has been using ice cores to study our own star, the Sun, and has discovered evidence of an ancient solar storm. In this second season of the Meridian we are also bringing you some field reporting from the Nordic Optical Telescope on La Palma, where a team of astronomers are trying to catch an ultra-hot Jupiter-sized exoplanet

The Meridian S02E02 : Galactic archeology & ash on the mountain

In the second episode of the second season Nic and Rebecca invite Diane Feuillet to the microphone. Diane is a researcher here at Lund Observatory working on galactic archaeology using stellar abundances, ages and kinematics. In this second season of the Meridian we are also bringing you some field reporting from the Nordic Optical Telescope on La Palma, where a team of astronomers are trying to catch an ultra-hot Jupiter-sized exoplanet

The Meridian S02E04 : The European Southern Observatory & an eathquake on the mountain

The European Southern Observatory, or ESO, is celebrating 60 years of scientific achievements in the southern hemisphere. Sweden is one of the founding members of ESO, and several astronomers from Lund have been actively involved over the years. In the fourth episode of the second season our podcast hosts, Nic Borsato and Rebecca Forsberg, invite professor emeritus Dainis Dravins to the microphone to tell us about both the Swedish and his own connection to the European Southern Observatory. In this second season of the Meridian we are also bringing you some field reporting from the Nordic Optical Telescope on La Palma, where a team of astronomers are trying to catch an ultra-hot Jupiter-sized exoplanet

The Mantis Network II : examining the 3D high-resolution observable properties of the UHJs WASP-121b and WASP-189b through GCM modelling

The atmospheres of ultra hot Jupiters (UHJs) are prime targets for the detection of molecules and atoms at both low and high spectral resolution. We study the atmospheres of the UHJs WASP-121b and WASP-189b by performing 3D general circulation models (GCMs) of these planets using high temperature correlated-k opacity schemes with ultra-violet (UV) absorbing species included. The GCM results are then post-processed at low and high spectral resolutions and compared to available data. The high resolution results are cross-correlated with molecular and atomic templates to produce mock molecular detections. Our GCM models produce similar temperature-pressure (T-p) structure trends to previous 1D radiative-convective equilibrium models of UHJs. Furthermore, the inclusion of UV opacities greatly shapes the thermal and dynamical properties of the high-altitude, low-pressure regions of the UHJ atmospheres, with sharp T-p inversions due to the absorption of UV light. This suggests that optical wavelength, high-resolution observations probe a dynamically distinct upper atmospheric region, rather than the deeper jet forming layers

The Mantis Network II: examining the 3D high-resolution observable properties of the UHJs WASP-121b and WASP-189b through GCM modelling

The atmospheres of ultra hot Jupiters (UHJs) are prime targets for the detection of molecules and atoms at both low and high spectral resolution. We study the atmospheres of the UHJs WASP-121b and WASP-189b by performing 3D general circulation models (GCMs) of these planets using high temperature correlated-k opacity schemes with ultra-violet (UV) absorbing species included. The GCM results are then post-processed at low and high spectral resolutions and compared to available data. The high resolution results are cross-correlated with molecular and atomic templates to produce mock molecular detections. Our GCM models produce similar temperature-pressure (T-p) structure trends to previous 1D radiative-convective equilibrium models of UHJs. Furthermore, the inclusion of UV opacities greatly shapes the thermal and dynamical properties of the high-altitude, low-pressure regions of the UHJ atmospheres, with sharp T-p inversions due to the absorption of UV light. This suggests that optical wavelength, high-resolution observations probe a dynamically distinct upper atmospheric region, rather than the deeper jet forming layers

The Meridian S02E00 : The Winter Solstice special episode

In this very special solstice episode of The Meridian Nic and Rebecca look back at some of the highlights of 2021. With the days growing ever longer here in the Northern Hemisphere they have rallied a troupe of PhD students to compete in the 2021 Astronomy Games! Nic is joined by Alvaro and Johan on his team and Rebecca has convinced Daniel and Madeleine to join her team. The Games were recorded in front of a live studio audience

3D Radiative Transfer for Exoplanet Atmospheres. gCMCRT: A GPU-accelerated MCRT Code

Radiative transfer (RT) is a key component for investigating atmospheres of planetary bodies. With the 3D nature of exoplanet atmospheres being important in giving rise to their observable properties, accurate and fast 3D methods are required to be developed to meet future multidimensional and temporal data sets. We develop an open-source GPU RT code, gCMCRT, a Monte Carlo RT forward model for general use in planetary atmosphere RT problems. We aim to automate the post-processing pipeline, starting from direct global circulation model (GCM) output to synthetic spectra. We develop albedo, emission, and transmission spectra modes for 3D and 1D input structures. We include capability to use correlated-k and high-resolution opacity tables, the latter of which can be Doppler-shifted inside the model. We post-process results from several GCM groups, including ExoRad, SPARC/MITgcm THOR, UK Met Office UM, Exo-FMS, and the Rauscher model. Users can therefore take advantage of desktop and HPC GPU computing solutions. gCMCRT is well suited for post-processing large GCM model grids produced by members of the community and for high-resolution 3D investigations

Vanadium oxide and a sharp onset of cold-trapping on a giant exoplanet

The abundance of refractory elements in giant planets can provide key insights into their formation histories1. Owing to the low temperatures of the Solar System giants, refractory elements condense below the cloud deck, limiting sensing capabilities to only highly volatile elements2. Recently, ultra-hot giant exoplanets have allowed for some refractory elements to be measured, showing abundances broadly consistent with the solar nebula with titanium probably condensed out of the photosphere3,4. Here we report precise abundance constraints of 14 major refractory elements on the ultra-hot giant planet WASP-76b that show distinct deviations from proto-solar and a sharp onset in condensation temperature. In particular, we find nickel to be enriched, a possible sign of the accretion of the core of a differentiated object during the evolution of the planet. Elements with condensation temperatures below 1,550 K otherwise closely match those of the Sun5 before sharply transitioning to being strongly depleted above 1,550 K, which is well explained by nightside cold-trapping. We further unambiguously detect vanadium oxide on WASP-76b, a molecule long suggested to drive atmospheric thermal inversions6, and also observe a global east–west asymmetry7 in its absorption signals. Overall, our findings indicate that giant planets have a mostly stellar-like refractory elemental content and suggest that temperature sequences of hot Jupiter spectra can show abrupt transitions wherein a mineral species is either present or completely absent if a cold trap exists below its condensation temperature8