bluuebunny/crossref_metadata_2025 huggingface dataset:
From disk midplanes to exoplanet atmospheres. The volatile chemical link.
Authors: Eistrup Christian
Published: October 2020

Exoplanetary science is now pushing to constrain the atmospheric compositions of exoplanets. This quest will be further aided by the next generation of facilities, such as the JWST and ground-based ELTs. Linking the observed composition of exoplanet atmospheres to where and how these atmospheres formed in their natal protoplanetary disks often involves comparing the observed exoplanetary atmospheric carbon-to-oxygen (C/O) ratio to a model of a disk midplane with a fixed chemical composition. In this scenario, chemical evolution in the midplane prior to and during the planet formation era is not considered. The C/O ratios of gas and ice in the disk midplane are simply defined by icelines of volatile molecules such as water and CO in the midplane. However, kinetic chemical evolution during the lifetime of the gaseous disk can change the relative abundances of volatile molecules, thus altering the C/O ratios of the planet-forming material. In my chemical evolution models, I utilize a large network of gas-phase, grain-surface and gas-grain interaction reactions, thus providing a comprehensive treatment of chemistry. In my talk, I will outline how such chemical reactions can cause the chemical composition in the disk midplane to evolve, how this affects the C/O ratios of the gas and solid material that form planets, and how such changes to the midplane chemical composition can lead to differences in exoplanet atmospheric compositions. These differences in exoplanet atmospheric compositions may be discernible with JWST observations.
Chemistry and dynamics in the atmospheres of the Ice Giants: from the troposphere to the ionosphere
Authors: Cavalié Thibault , Dobrijevic Michel , Hue Vincent , Leconte Jérémy
Published: October 2020

Uranus and Neptune have only been visited by one spacecraft, Voyager 2. Their atmospheres thus remain mysterious in terms of composition and dynamics, despite repeated efforts to observe them from the ground and earth-orbiting telescopes. Deep composition is key to constrain internal and formation processes but is difficult to measure with remote sensing techniques because of the condensation into various cloud layers of several key volatiles. Chemical complexification initiated by solar UV and magnetospheric electrons, as well as contamination by external sources (dust, comets, ring and satellite material), all occurring in the upper atmosphere but diffusing downward, can further complicate the situation because of the mixing of these various components caused by dynamics.In this context, an atmospheric entry probe to measure key volatiles (e.g. noble gases, C, N, S, P) in the upper troposphere is highly desirable (Mousis et al. 2018, Cavalié et al. 2020) and would benefit from direct observational support from an orbiting spacecraft (Fletcher et al. 2020), as well as contextual ground-based supporting observations. All these measurements are essential to constrain the chemistry models we develop to better understand the composition and dynamics in the Ice Giant atmospheres. With a coherent set of models, ranging from 1D thermochemical and diffusion models for the tropospheres (Cavalié et al. 2017, Leconte et al. 2017, Venot et al. 2019, 2020) to 2D time-dependent photochemical models for the stratospheres and ionospheres (Hue et al. 2018, Dobrijevic et al. 2020), we aim at contributing to a better understanding of the Ice Giant composition and dynamics.
Europa's dynamic ocean: Taylor columns, eddies, convection, ice melting and salinity
Authors: Ashkenazy Yosef , Tziperman Eli
Published: October 2020

The deep ocean (~100 km) of Europa, Jupiter’s moon, is covered by a thick (tens of km) icy shell, and is one of the most probable places in the solar sys- tem to find extraterrestrial life. Yet, its ocean dynamics and its interaction with the ice cover have so far received little attention. Previous studies sug- gested that Europa’s ocean is turbulent, yet neglected to take into account the effects of ocean salinity and appropriate boundary conditions for the ocean’s temperature. Here, the ocean dynamics of Europa is studied using global ocean models that include non-hydrostatic effects, a full Coriolis force, con- sistent top and bottom heating boundary conditions, and including the effects of melting and freezing of ice on salinity. The density is found to be dominated by salinity effects and the ocean is very weakly stratified. The ocean exhibits strong transient vertical convection, eddies, low latitude zonal jets and Tay- lor columns parallel to Europa’s axis of rotation. In the equatorial region, the Taylor columns do not intersect the ocean bottom and propagate equatorward, while off the equator, the Taylor columns are static. The meridional oceanic heat transport is intense enough to result in a nearly uniform ice thickness, that is expected to be observable in future missions.
A High-Resolution Linelist for Molecular Oxygen
Authors: Somogyi Wilfrid , Yurchenko Sergey
Published: October 2020

Molecular oxygen (O2) is of particular interest in exoplanetary observations not least of all as an important biosignature on habitable planets. The atmospheric absorption bands are well studied, but a complete and accurate, high-resolution linelist is yet to be produced. Owing to their symmetry, the commonly employed electric dipole approximation is not valid for homonuclear diatomic molecules, and their rovibrational spectra are instead dominated by higher order transitions moments. These higher-order moments, such as the electric quadrupole and magnetic dipole, give rise to transition linestrengths that are orders of magnitude weaker than typical electric dipole transitions. Although such transitions are observable for atmospheric path lengths, their weak nature makes laboratory measurements especially challenging. In this work we develop and apply ab initio computational techniques to produce an accurate electric quadrupole spectrum of molecular oxygen presented for use in atmospheric retrievals across a range of temperatures, and made available through the ExoMol database.
Bifocal Panoramic Stereoscopic Camera for Lunar Exploration
Authors: Pernechele Claudio , Cremonese Gabriele , Fantinel Daniela , Lucchetti Alice , Lessio Luigi , Massironi Matteo , Pajola Maurizio , Paoletti Lorenzo , Pozzobon Riccardo , Re Cristina , Saggin Bortolino , Scaccabarozzi Diego , Simioni Emanuele , Abbattista Cristoforo , Banfi Emilio , Consolaro Luca , Dionisio Cesare , Kuijpers Mark , Mura Daniele , Piantone Stefano ,   BIPS TEAM
Published: October 2020

A bifocal panoramic stereoscopic camera (BIPS) has been designed a realized as a terrestrial prototype. The core of the camera is a novel Bifocal Panoramic Lens (BPL) we designed and realized, which is able to carry out a panoramic field of 360° in azimuth, 100° in elevation (+60°/-40° with respect to the horizon) and, simultaneously, an enlargement of a part of the panoramic field. All of that using an unique image sensor and avoiding any moving part. BIPS consists of a twin couple of BPLs settled in an appropriate stereoscopic baseline. It allows the monitoring of the surrounding environment in stereoscopic (3D) mode and, simultaneously, to capture a higher resolution stereoscopic images to analyze scientific cases. If mounted on a planetary rover, BIPS merge engineering stereoscopic capabilities for autonomous driving with an optical stereoscopic channel for scientific purpose, making it a new paradigm in the planetary rovers' framework.The operational aims include the identification of boulders, crevasses and other surfaces that can be obstacles for rover trafficability, in addition to the 3D reconstruction of exploration sites for improving situation awareness during both roving and human operations. On the other hand, the correct and detailed 3D reconstruction of exploring sites allows detailed measurements of many geological features such as: sedimentary structures (strata attitudes, geometry and thickness); fracturing networks (attitudes and persistence); folds and faults systems (orientation, vergence and displacement); veining systems (frequency, orientation and thickness); mounds, vents and ridges (slope and aspect); boulders (size frequency distribution). All these measurements are pivotal for the understanding of tectonic, sedimentologic, volcanic, erosive, fluid-rock interaction and impact processes on planetary surfaces.In this paper we describe the optical characteristics of a BPL, the realized terrestrial BIPS, the stereoscopic calibration and some possible scientific cases within the lunar exploration framework.
Observing atmospheric HCN on Titan from space and ground-based observatories: an inter-comparison study from Herschel, APEX and IRAM 30m telescopes
Authors: Rengel Miriam , Shulyak Denis , Hartogh Paul , Sagawa Hideo , Moreno Raphael , Jarchow Christopher
Published: October 2020

In support of the Herschel Space Observatory and in the framework of the program “Water and Related Chemistry in the Solar System” [1], hydrogen cyanide (HCN) on Titan was observed from ground at submillimetre wavelengths. We carried submm heterodyne spectroscopy observations of HCN (4-3) at 345.5 GHz with the Atacama Pathfinder Experiment (APEX) and the APEX-2 heterodyne receiver, and of HCN (3-2) at 265.9 GHz with the Institut de radioastronomie millimétrique (IRAM) 30-m telescope (IRAM 30m) and the Heterodyne Receiver Array (HERA) receiver in Titan atmosphere. Observations were carried out on June 16, 2010, and March 19, 2011, under non-favorable and favorable weather conditions, respectively. We report here the APEX and IRAM 30m observations, and by using a line-by-line radiative transfer code and the least-squares fitting technique, the analysis to infer the HCN abundance. Our HCN mixing-ratio estimations confirm the result of Marten et al. (2002) [2]. We compare our results with the those with Herschel/PACS and SPIRE acquired during 2010 [3,4]. Measured HCN abundances on Titan with data acquired at different epochs and transitions exhibit similar abundance distributions. Beyond the intrinsic scientific interest, these observations proven their usefulness in supporting spacecraft observations of Solar System bodies, in particular, of Titan’s atmosphere.[1] Hartogh, P.; Lellouch, E.; Crovisier, J., et al. 2009, Planetary and Space Science, Volume 57, Issue 13, p. 1596-1606. [2]  Marten, A.; Hidayat, T.; Biraud, Y. et al.  Icarus, 2002, Volume 158, Issue 2, p. 532-544. [3]  Rengel, M.; Sagawa, H.; Hartogh, P., et al. 2014, A&A, 561. [4]  Courtin, R., Swinyard, B. M., Moreno, R., et al. 2011, A&A, 536, L2.
Inverted channels, polygonal fractures and layered mounds from the Makgadikgadi Pan of Botswana: possible analogues for Martian morphologies
Authors: Franchi Fulvio , MacKay Ruaraidh , Selepeng Ame , Barbieri Roberto
Published: October 2020

Inverted channels with polygonal fractures and layered mounds from the Ntwetwe pan in the Makgadikgadi Basin (central Botswana) have been herein investigated. These morphologies are from an evaporitic basin (the Makgadikgadi Basin) that is the remnant of an ancient Plio-Pleistocene lake and is currently part of the world’s largest evaporitic system.The mounds in the Ntwetwe pan are characterized by a layered structure and low relief (max. 5 m above the pan floor) and can be in excess of 2 km wide. The mounds consist mainly of loose (non-lithified) sand and silt with high moisture contents, even during the dry season. Geophysical investigations have shown that groundwater processes, particularly those related to the capillary fringe that rises and conveys moisture through the mounds, are factors that make mound sediments resistant to wind erosion.The inverted channels, identified in the southern part of the Ntwetwe pan, are characterized by gentle reliefs and depressions, which depend upon the distribution of calcretes and indurated sediments. Large scale (up to 100 m wide) polygonal fractures localized at the front of the fan, disappear at the transition with the present-day pan floor.We consider that these particularmounds, withinthe Ntwetwe pan, are remnants of the strandline of the paleo-Makgadikgadi Lake, and that the inverted channels representdistributary channels of a relict fan delta,formed by an ephemeral river, most likelythe paleo-Boteti River, during a Lake Paleo-Makgadikgadihighstand stage. We consider that largescale (up to 100 m wide) polygonal fractures, located on thechannel-mouth lobes, representlarge-scale desiccation cracks formed byrapid water evaporation from deltadeposits.The results of this investigation highlight the importance of the paleo-drainage system and itsinteractions with thewater table and wind-deflation as main geomorphological factors within salt pan environments. The mounds in the Makgadikgadi pans also show strong geomorphic similarities to spring mounds on the surface of Mars, localized in equatorial layered deposits (ELDs). These ELDs mounds are considered to result from cyclical groundwater upwelling, evaporation and wind deflation. The geological processes that resulted in the formation of mounds within the Makgadikgadi may, therefore, help to explain how similar layered deposits formed on Mars and confirm existing theories.
Constraints on aerosol structure and formation in the atmosphere of the ice giants from microphysics simulations
Authors: Toledo Daniel , Irwin Patrick , Rannou Pascal , Fletcher Leigh , Yela Margarita
Published: October 2020

A number of images and analyses have demonstrated the presence of hazes and clouds in the atmosphere of the ice giants. While the formation of hazes is attributed to the methane dissociation in the high stratosphere by solar UV and energetic particles that leads to a number of chemical reactions (e.g. Moses et al., Icarus, 307, 2018), the observed clouds are the result of the condensation of CH4 and H2S in the troposphere (e.g. Irwin et al., Nature Astronomy, 2018). However, the lack of current limb observations taken at different tangent heights limits our knowledge about the vertical structure and optical properties of these aerosols. In this work, we will present different results obtained with a coupled cloud-haze microphysical model (Toledo et at., Icarus, 333, 2019; Toledo et at., Icarus, 350, 2020) used to constrain the particle size, density, vertical structure and time scale of aerosols in the ice giants. Our simulations show, among other results, high precipitation rates at pressures greater than 0.5 bar and timescales ranging from years (for the haze) to a few hours (CH4 clouds).
A SPACE JOURNEY Astrobiology Role-Play Game for Public Engagement and Education
Authors: Boccato Caterina , Barosso Elena , Maio Francesco , Pignatelli Ezio , Ricciardi Sara , Sandrelli Stefano
Published: October 2020

The subject of the proposed talk is an astrobiology Role Play Game (RPG), Space Journey, that we have realized for public engagement and informal educational purposes. This work is the result of an open collaboration among the academic world, represented by public engagement professionals of the National Institute for Astrophysics and two young students - a mechanical engineering and a physicists -, the school’s world, represented by a secondary schools professor of physics, and with the consultancy of the GAME Science Research Center (GAME.SCI RE.CENTER) which is an interuniversity research center that aims at promoting, supporting and spreading the research in the field of Game Science.The set of Space Journey is the known space, in particular our Galaxy, and the general screenplays that the Master should use are based on space exploration and on interaction with alien forms of life, from the most simple to the more complex.As in any RPG any player interprets a character. In total, there are six characters, that means six players: a physicist, a biologist, a psychologist, an engineer, a chemists and a geologists.They are the spaceship crew and they have to solve many problems in their journey, mainly, but not only, scientific and technological problems. In this kind of creative approach for public engagement and for informal education, we would like to underline some aspects besides the scientific ones: the high collaborative one, the interdisciplinary and, in general, the use of “Game-based learning” (GBL) approach. GBL describes an educational and psychological approach, according to which children make sense of the world through play. Play-based learning programs are student-centered learning approaches, focused on the fully autonomous development of children’s cognitive, social, experiential and creative potential through play.This RPG is currently under a final implementation phase but we successfully tested the beta version during our participation to the Festival of Game - PLAY (Modena, 4-7 April 2019).
Fifty AU Study of the chemistry in the disk/envelope system of Solar-like protostars (FAUST) Large program first results: the hot corino in L1551 IRS5
Authors: Bianchi Eleonora , Yamamoto Satoshi , Ceccarelli Cecilia , Chandler Claire , Codella Claudio , Sakai Nami ,   FAUST Team
Published: October 2020

Detection of hot corinos in Solar-like protostars has been so far mostly limited to Class 0 objects, hampering our understanding of their origin and evolution. Recent evidence suggests that planet formation probably starts already in Class I protostars, representing a key step in our understanding of their chemical composition at the planet formation scale. Therefore, understanding the fate of hot corinos in Class I protostars has become of paramount importance. In this context, we report the discovery of a hot corino at the heart of the prototypical Class I source L1551 IRS5, obtained via ALMA observations as part of the Large Program FAUST (Fifty AU Study of the chemistry in the disk/envelope system of Solar-like protostars). More specifically, FAUST is the first ALMA Large Program based on astrochemistry and is designed to survey the chemical composition of a sample of 13 Class 0 and I protostars at the planet-formation scale.We detected in L1551 IRS 5 several emission lines from interstellar complex organic molecules (iCOMs) such as methanol and its most abundant isotopologues, as well as methyl formate and ethanol.  The line emission is bright toward the north component (N), although a hot corino in the south component, cannot be excluded. The non-LTE analysis of the methanol lines towards N provides constraints on the gas temperature (~ 100 K), density (≥ 1.5 x 108 cm-3) and emitting size (~0.15”, i.e. ~ 10 au in radius). The lines are predicted to be optically thick, the 13CH3OH line having an opacity ≥ 2. The methyl formate and ethanol column densities relative to methanol are ≤ 0.03 and ≤ 0.015, respectively, compatible with those measured in Class 0 sources. Thus, the present observations towards L1551 IRS5 agree with little chemical evolution in hot corinos from Class 0 to I. 
Jupiter's Temperate Belt/Zone Contrasts at Depth Revealed By Juno
Authors: Fletcher Leigh N. , Oyafuso Fabiano , Allison Michael , Ingersoll Andrew , Li Liming , Kaspi Yohai , Galanti Eli , Wong Michael , Orton Glenn , Zhang Zhimeng , Li Cheng , Levin Steve , Bolton Scott
Published: October 2020

Introduction:  The locations of Jupiter’s cloud-top east-west jets are relatively constant over time and define the cyclonic belts and their neighbouring anticyclonic zones.  Thermal-infrared observations of the upper troposphere reveal cool temperatures, elevated abundances of condensate and disequilibrium gases, and enhanced cloud opacity over the zones, and the opposite over the belts (Gierasch et al., 1986, doi:10.1016/0019-1035(86)90125-9).  This distribution implies upwelling motions in zones and subsidence in belts. However, this picture has been called into question by the observed eddy-momentum flux convergence into the eastward jets (and divergence from the westward jets), which suggests a compensating flow in the opposite direction, from belts into zones, which is partially supported by the distribution of lightning at low latitudes (Little et al., 1999, doi:10.1006/icar.1999.6195).  It is possible that two different atmospheric regimes exist:  a deep regime where eddies are able to drive the zonal flows, and a higher-altitude regime where those zonal flows decay with height. Reconciling this apparent inconsistency remains a key challenge for the understanding of Jupiter’s atmosphere, and Juno observations of the deeper atmosphere shed important light on this issue. Methodology:  Juno’s Microwave Radiometer (MWR) examines the vertical structure of Jupiter’s belts and zones below the clouds by sounding in six channels from 1.4 to 50 cm, sensing from the cloud-tops at ~0.7 bar to pressures greater than 300 bar. Initial results (Li et al. 2017, doi:10.1002/2017GL073159) revealed contrasts at depth that bore a potential resemblance to the belt/zone structure in the upper troposphere.  We report on progress in our analysis of averaged nadir microwave brightness and its emission-angle dependence from the first two years of Juno’s mission.  We investigate the correlation between the meridional gradient of the brightness temperature at all emission angles and the cloud-top zonal winds.  These brightness temperature gradients reflect changes in gaseous opacity (e.g., ammonia and water), kinetic temperature, or both. We explore the implications of the contrasts observed between belts and zones as a function of depth sounded by MWR.Preliminary Results:  Meridional brightness temperature gradients above the clouds (p
The origin of the obliquity in planetary systems studied with infrared interferometry
Authors: Kraus Stefan
Published: October 2020

Observations of the Rossiter-McLaughlin effect have revealed that the orbits of many exoplanets are misaligned with respect to the stellar rotation axis. Various scenarios have been proposed that associate the orbit obliquity either with multi-body interactions or dynamical processes in the disc during the planet formation process. In this talk, I will present how infrared interferometry allows us to study the origin of the planet obliquity:In the first part of the talk I will present observations that reveal the recently-posted disc tearing effect, where the gravitational torque of companions on misaligned orbits can tear the disc apart into distinct rings that precess independently around the central objects. We imaged the triple system GW Orionis using VLTI, CHARA, ALMA, SPHERE, and GPI and discover three rings in thermal light and an asymmetric structure with radial shadows in scattered light. The inner-most ring is eccentric (e=0.3; 43 au radius) and strongly misaligned both with respect to the orbital planes and with respect to the outer disc. Modelling the scattered light signatures and the shape of the shadows cast by the misaligned ring allows us derive the shape and 3-dimensional orientation of the disc surface, revealing that the disc is strongly warped and breaks at a radius of about 50 au. Based on the measured triple star orbits and disc properties, we conducted smoothed particle hydrodynamic simulations which show that the system is susceptible to the disc tearing effect. The ring offers suitable conditions for planet formation, providing a mechanism for forming wide-separation planets on highly oblique orbits. Our results imply that there may exist a significant, yet undiscovered population of long-period planets on highly oblique orbits that has formed around misaligned multiple systems.In the second part I will show how infrared interferometry can be used to search for this predicted population of wide-separation planets on oblique orbits, probing a highly complementary regime to the parameter space accessible with the Rossiter-McLaughlin effect. I will present the first study where the spin-orbit alignment has been measured for a directly-imaged exoplanet, namely on Beta Pictoris b. We used VLTI/GRAVITY spectro-interferometry with an astrometric accuracy of 1 microarcsecond to measure the photocenter displacement associated with the stellar rotation. Taking inclination constraints from astroseismology into account, we constrain the 3-dimensional orientation of the stellar spin axis and find that Beta Pic b orbits its host star on a prograde orbit with a small obliquity angle. I will conclude by offering a near-term perspective on how infrared interferometry with the proposed BIFROST beam-combination instrument could advance our understanding of the planet formation process and of the early dynamical evolution of exoplanetary systems.
A self-consistent thermodynamic approach to compute the interiors of irradiated ocean planets
Authors: Aguichine Artyom , Mousis Olivier , Deleuil Magali , Marcq Emmanuel
Published: October 2020

Planetary interior models rely on the thermodynamic properties of the used materials. Equations of states (EOSs) are key ingredients to compute internal structures, as they link the pressure and density profiles, and leave a unique solution satisfying all equations describing the interior of the planet. Often, when thermodynamic data are lacking, the formulation of EOSs allow extrapolation in both pressure and temperature. The effect of temperature on EOSs is often minor, implying that models of isothermal planets provide consistent results. This approach meets limitations in the case of fluids (liquids, gases and supercritical fluids), whose properties are very sensitive to variations in temperature. Here we propose a way to compute the relevant thermodynamic parameters in supercritical water from the most recent EOSs, in order to compute the internal structures of irradiated ocean planets, coupled with a 1D convective-radiative atmospheric model. Our results allow a better understanding of the diversity of observed sub-Neptunes, linking their internal structure to formation conditions.
Educational Resources for the EPN24 Planetary Field Analogue Sites
Authors: Cane Rosie , Thompson Tony , Utreras José , Roche Paul
Published: October 2020

The Europlanet 2024 Research Infrastructure (RI) provides free access to the world’s largest collection of planetary simulation and analysis facilities. The project is funded through the European Commission’s Horizon 2020 programme and runs for four years from February 2020 until January 2024. The Transnational Access (TA) programme supports all travel and local accommodation costs for European and international researchers to visit 24 laboratory facilities and 5 Planetary Field Analogues (PFA) [1].As part of the education and inspiration tasks associated with Europlanet 2024 RI, we have produced classroom resources aimed at age 10-14 year olds relating the conditions found within the PFA sites to astrobiology and the habitability of Mars.These resources have been produced around all PFA sites:Rio Tinto River (Spain)
Iceland Field Sites (Iceland)
Danakil Depression (Ethiopia)
Kangerlussuaq Field Site (Greenland)
Makgadikgadi Salt Pans (Botswana)
These resources link in with common areas found in worldwide STEM curriculums, such as volcanism, pressure, pH and evaporation. To achieve this, we have filmed lab-based demonstrations and included them in a classroom lesson plan alongside teachers' notes. In addition, each lesson plan focuses on how the conditions of the PFA’s could affect the habitability of Mars, as can be seen in Figure 1.Following studies such as Salimpour et al 2020 [2], highlighting the extent to which astronomy has been incorporated into school curriculums, we have chosen to highlight three subject areas with lower representation in high schools into our resources; physics, space exploration and astrobiology.As these analogue sites can be linked to more planetary bodies than just Mars, our next steps are to create similar resources based around the habitability of the icy moons of the Solar System.Figure 1. Outline of resource plans for Europlanet Planetary Field Analogues.References: [1] The Europlanet Society, TA1 Planetary Field Analogues (PFA). Available at: https://www.europlanet-society.org/europlanet-2024-ri/ta1-pfa. [2] Salimpour, S., Bartlett, S., Fitzgerald, M.T. et al. The Gateway Science: a Review of Astronomy in the OECD School Curricula, Including China and South Africa. Res Sci Educ (2020). https://doi.org/10.1007/s11165-020-09922-0Acknowledgement: Europlanet 2024 RI has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 871149.
Monitoring Venus cloud top: the VenSpec-U spectrometer on board ESA EnVision
Authors: Marcq Emmanuel , Guignan Gabriel , Lustrement Benjamin , Montmessin Franck , Lasue Jérémie , Bézard Bruno , Vandaele Ann Carine , Helbert Jörn , Widemann Thomas , Wilson Colin , Ghail Richard
Published: October 2020

Instrument descriptionThe VenSpec-U instrument is a dual channel UV spectral imager (low and high spectral resolution channels, “LR” and “HR” hereafter), part of the VenSpec spectrometer suite on board the proposed Venus orbiter EnVision. Each channel consists of an entrance baffle, an objective composed of two lenses and a stop diaphragm, and a spectrometer composed of a slit and a toroidal holographic grating. It also includes s shortpass filter to reject the wavelengths above the higher limit of both channel bands and a zero-order trap to avoid straylight due to internal reflexions of the grating zero-order. The optical layout is presented in Figure 1. Both LR and HR slits are parallel and the optical layout is such that both channels have the same instantaneous field of view (FoV), allowing simultaneous observations and calibrations. Each slit image is then spectrally dispersed by its respective toroidal holographic grating and is formed on a shared CMOS back-side illuminated detector. 
Figure 1: VenSpec-U optical layout overview, with the HR and LR channels respectively on the left and on the right.
 The narrow-slit axis of the detector contains the spectral information, whereas the long-slit axis contains the spatial information along the 22.5° FoV of each slit. The spectra of LR and HR channels are dispersed one above the other on the focal plane. The remaining spatial direction is provided through orbital scrolling (“pushbroom” strategy). Binning on the spatial axis is performed on the detector. The detector will be controlled such that the integration time and the binning scheme is adjusted independently (and simultaneously) for each channel giving high flexibility and providing parameters for the optimisation of each acquisition.Instrument PerformanceAccording to our forward model based on HST-STIS [Jessup et al., 2015] and SPICAV-UV heritage [Marcq et al., 2020], this shall be sufficient to measure the targeted species (SO, SO2, UV absorber) with a relative accuracy better than 25%. These measurements shall allow to characterize variability of Venus cloud top on temporal scales ranging from hours to years and spatial scales ranging from a few kilometers to planetary scale in relation to the climate and/or present day volcanic activity of Venus.BibliographyK. L. Jessup et al., Coordinated Hubble Space Telescope and Venus Express Observations of Venus’ upper cloud deck, Icarus 258, 2015
E. Marcq et al., Climatology of SO2 and UV absorber at Venus’ cloud top from SPICAV-UV nadir dataset, Icarus 335, 2020
Are sub-Neptunes irradiated ocean planets?
Authors: Mousis Olivier , Deleuil Magali , Aguichine Artyom , Marcq Emmanuel , Acuna Aguirre Lorena
Published: October 2020

Small planets (1-3.9 Rearth) constitute more than half of the inventory of the 4000-plus exoplanets discovered so far. Smaller planets are sufficiently dense to be rocky, but those with radii larger than 1.6 Rearth are thought to display in many cases hydrogen/helium gaseous envelopes up to 30% of the planetary mass. These low-mass planets are highly irradiated and the question of their origin, evolution, and possible links remains open. Here we show that close-in ocean planets affected by greenhouse effect display hydrospheres in supercritical state, which generate inflated atmospheres without invoking the presence of large hydrogen/helium gaseous envelopes. We present a new set of mass-radius relationships for ocean planets with different compositions and different equilibrium temperatures, which are found to be well adapted to low-density sub-Neptune planets. Our model suggests that super-Earths and water-rich sub-Neptunes could belong to the same family of planets, i.e. hydrogen/helium-free planets, with differences between their interiors simply resulting from the variation in the water content. 
SSHADE, its solid spectra databases and its future band list of molecular solids
Authors: Schmitt Bernard , Bollard Philippe , Albert Damien , Bonal Lydie , Poch Olivier ,   SSHADE Consortium
Published: October 2020

The SSHADE database infrastructure (http://www.sshade.eu) hosts spectral data of many different types of solids: ices, snows, minerals, carbonaceous matters, meteorites, IDPs and other cosmo-materials,… covering a wide range of wavelengths: from X-rays to millimeter wavelengths.Its Search / Visualization / Export interface is open to the community since February 2018. It currently contains over 3500 spectra.We are currently developping a 'band list' database that will provide the band parameters (position, width, intensity, isotopic  species, attribution mode, ...) of a number of solids of astrophysical and planetary interest in various phases (crystalline, amorphous, ...) and mixtures (different compositions) and at different temperatures or pressures. We will first feed this database from critical compilations of all data published in various journals for pure ices and molecular solids (hydrates, clathrates, sulfur compounds, ...) and their mixture, including the own works of the members of the SSHADE consortium.An efficient search tool will allow to filter on various parameters such as band position (or spectral range) and intensity, expected molecular or atomic formula, type of vibration (e.g. infrared, Raman, fluorescence...) and display the results graphically. A demonstrator prototype is online in the 'old GhoSST' database (https://ghosst.osug.fr/search/band).This band list will be a key tool for astronomers and space explorers to identify unknown absorption bands observed in the spectra of the surface or atmosphere of many objects in the solar system. Once the best candidate solid selected by the user the tool will point to the best relevant spectral data present in the SSHADE databases.   
Characterising Two Ultra-Hot Jupiters with the Hubble Space Telescope
Authors: Edwards Billy , Changeat Quentin , Pluriel William , Whiteford Niall , Yip Kai Hou , Baeyens Robin , Taylor Jake , Tsiaras Angelos , Al-Refaie Ahmed , Waldmann Ingo , Beaulieu Jean-Philippe
Published: October 2020

The Hubble Space Telescope’s Wide Field Camera 3 (WFC3) has been widely used for transmission and emission spectroscopy of exoplanet atmospheres, identifying the main molecular constituents, detecting the presence of clouds and probing their thermal structure. Hubble observations of the emission spectra of a number of ultra-hot Jupiters have led to somewhat surprising results. Initially, these very hot planets were predicted to have inverted temperature pressure profiles due to strong optical absorption by TiO/VO in the upper atmospheres. However, observations of their emission spectra have been inconclusive on their thermal structure and composition. While some datasets show rich spectral features, others can be fit with simple blackbody models.We will present the analysis of Hubble WFC3 transmission and emission spectra for two ultra-hot Jupiters: WASP-76 b and KELT-7 b. In each case, the data was reduced and fitted using the open-source codes Iraclis and Taurex3. Previous studies of the WFC3 transmission spectra of WASP-76 b found hints of TiO and VO or non-grey clouds. Accounting for a fainter stellar companion to WASP-76, we reanalyse this data and show that removing the effects of this background star changes the slope of the spectrum, resulting in these visible absorbers no longer being detected, removing the need for a non-grey cloud model to adequately fit the data but maintaining the strong water feature previously seen. However, our analysis of the emission spectrum suggests the presence of titanium oxide (TiO) and an atmospheric thermal inversion. Meanwhile, our study of KELT-7 b uncovers a rich transmission spectrum which suggests the presence of water and H-. In contrast, the extracted emission spectrum does not contain strong absorption features and, although it is not consistent with a simple blackbody, it can be explained by a varying temperature-pressure profile, collision induced absorption (CIA) and H-. These finding bring new insights into the nature of this intriguing class of planets but more data is required to fully understand them and thus we will also present the anticipated results of further characterisation.
Impact of gradients at the Martian terminator on the retrieval of ozone from TGO/NOMAD-UVIS
Authors: Piccialli Arianna , Vandaele Ann Carine , Willame Yannick , Aoki Shohei , Depiesse Cedric , Trompet Loic , Neary Lori , Viscardy Sebastien , Daerden Frank , Erwin Justin , Thomas Ian R. , Ristic Bojan , Mason Jon P. , Patel Manish , Bellucci Giancarlo , Lopez-Moreno Jose-Juan
Published: October 2020

. IntroductionRapid variations in species concentration at the terminator have the potential to cause asymmetries in the species distributions along the line of sight (LOS) of a solar occultation experiment. Ozone, in particular, displays steep gradients across the terminator of Mars due to photolysis [1]. Nowadays, most of the retrieval algorithms for solar and stellar occultations rely on the assumption of a spherically symmetrical atmosphere. However, photochemically induced variations near sunrise/sunset conditions need to be taken into account in the retrieval process in order to prevent inaccuracies.Here, we investigated the impact of gradients along the LOS of the solar occultation experiment TGO/NOMAD-UVIS for the retrieval of ozone under sunrise/sunset conditions. We used the diurnal variations in the ozone concentration obtained from photochemical model calculations together with an adapted radiative transfer code.2. The NOMAD UVIS channelNOMAD is a spectrometer composed of 3 channels: 1) a solar occultation channel (SO) operating in the infrared (2.3-4.3 μm); 2) a second infrared channel LNO (2.3-3.8 μm) capable of doing nadir, as well as solar occultation and limb; and 3) an ultraviolet/visible channel UVIS (200-650 nm) that can work in the three observation modes [2,3].The UVIS channel has a spectral resolution
What lies immediately outside of the heliosphere in the very local interstellar medium (VLISM): What will ISP detect?
Authors: Linsky Jeffrey , Redfield Seth
Published: October 2020

The Interstellar Probe (ISP) will provide the first directmeasurements of interstellar gas and dust when it travels far beyond theheliopause where the solar wind no longer influences the ambient medium.We summarize in this presentation what we have been learning about the VLISMfrom 20 years of remote observations with the high-resolution spectrographson the Hubble Space Telescope. Radial velocity measurements of interstellarabsorption lines seen in the lines of sight to nearby stars allow us tomeasure the kinematics of gas flows in the VLISM. We find that the heliosphereis passing through a cluster of warm partially ionized interstellar clouds.The heliosphere is now at the edge of the Local Interstellar Cloud (LIC) andheading in the direction of the slighly cooler G cloud. Two other warm clouds(Blue and Aql) are very close to the heliosphere. We find that there is alarge region of the sky with very low neutral hydrogen column density, whichwe call the hydrogen hole. In the direction of the hydrogen hole is thebrightest photoionizing source, the star Epsilon Canis Majoris (CMa). Extremeultraviolet photons from this star produce a Stromgren sphere region ofionized gas as large as the Local Cavity (extending to 100-200 parsecs)and produce Stromgren shells at the outer regions of the local warm cloudsincluding the LIC.When the ISP passes beyond the hydrogen wall at a distance of about 500 AU,it will likely enter the outer edge of the LIC where photoionization fromEpsilon CMa plays an important role. Analysis of Hubble observations ofinterstellar absorption proves estimates of the densities, temperature,pressure, and flow properties of the main portion of the LIC, but we havelittle informtion on these properties at the LIC's edge. Comparison with theinflow vector of neutral helium measured by IBEX and Ulysses indicates aslightly different flow speed and direction than the mean flow of the LIC gas.ISP will provide direct measurements of the flow and gas properties of thispoorly understood region. In particular, ISP will provide information onhow photoionization from Epsilon CMa influences warm clouds through ionization,heating, and perhaps pressure balance. This information may resolve questionsconcerning the magnetic field surrounding the heliosphere.
Balance at the edge of the diamagnetic cavity: first results from a Particle-In-Cell simulation
Authors: Beth Arnaud , Gunell Herbert , Götz Charlotte , Hamrin Maria , Nilsson Hans , Simon Wedlund Cyril
Published: October 2020

A common plasma feature which has been observed at comets during a relatively high outgassing activity is the presence of a magnetic field-free region, the so-called diamagnetic cavity. Observed for the first time at 1P/Halley, such structures have also been crossed many times at low relative speed at 67P/Churyumov-Gerasimenko by the ESA/Rosetta spacecraft.Many questions have been raised about the origin of this boundary. It is quite clear that, as one goes from an unmagnetised to a magnetised medium, one of the forces playing a role is the magnetic (pressure and tension) force. But what other force counter-balances the latter and helps form the boundary? For 1P/Halley, one formerly accepted explanation was the ion-neutral friction which has been investigated many times with magneto-hydrodynamic and hybrid simulations. However, the ion-neutral friction does not explain the observations at 67P/C-G as the outgassing rate was much lower than that of 1P/Halley.In this work, we investigate the balance between the electromagnetic forces at the boundary with a collisionless Particle-In-Cell 1D3V simulation and the open source code Smilei. It allows us to go down to scales which are not modelled by the more common MHD or hybrid simulations. In addition, this fully kinetic simulation give us access to the different moments (e.g., number density, mean velocity, pressure tensor) of the distribution function without extra assumptions (e.g., Ohm's law and adiabatic electrons). In particular, we investigate at the balance between the different forces at play on the electrons, i.e., the electron pressure gradient and the Lorentz force.For example, first results show that there is a sharp increase in the electric field at the boundary which decelerates ions coming from the diamagnetic cavity before reaching the magnetised part and being backstreamed towards the comet.
Preliminary results of Space Weather conditions encountered by BepiColombo during the first phase of its cruise
Authors: Sanchez-Cano Beatriz , Moissl Richard , Heyner Daniel , Huovelin Juhani , Mays M. Leila , Odstrcil Dusan , Lester Mark , Bunce Emma J. , James Matthew K. , Witasse Olivier , Benkhoff Johannes
Published: October 2020

Planetary Space Weather is the discipline that studies the state of the Sun and how it interacts with the interplanetary and planetary environments. It is driven by the Sun’s activity, particularly through large eruptions of plasma (known as coronal mass ejections, CMEs), solar wind stream interaction regions (SIR) formed by the interaction of high-speed solar wind streams with the preceding slower solar wind, and bursts of solar energetic particles (SEPs) that form radiation storms. This is an emerging topic, whose real-time forecast is very challenging because among other factors, it needs a continuous coverage of its variability within the whole heliosphere as well as of the Sun’s activity to improve forecasting. The long cruise of BepiColombo constitutes an exceptional opportunity for studying the Space Weather evolution within half-astronomical unit (AU), as well as in certain parts of its journey, can be used as an upstream solar wind monitor for Venus, Mars and even the outer planets. This work will present preliminary results of the Space Weather conditions encountered by BepiColombo since its launch until mid-2020, which includes data from the solar minimum of activity and few slow solar wind structures. Data come from three of its instruments that are operational for most of the cruise phase, i.e., the BepiColombo Radiation Monitor (BERM), the Mercury Planetary Orbiter Magnetometer (MPO-MAG), and the Solar Intensity X-ray and particle Spectrometer (SIXS). Modelling support for the data observations will be also presented with the so-called solar wind ENLIL simulations.
Atmospheric nitrogen at the time when life evolved on Earth
Authors: Gebauer Stefanie , Grenfell John Lee , Lammer Helmut , de Vera Jean-Pierre Paul , Sproß Laurenz , Airapetian Vladimir S. , Sinnhuber Miriam , Rauer Heike
Published: October 2020

The amount of nitrogen present in the atmosphere at the time when life evolved on Earth is central for understanding the production of prebiotic molecules and hence, is a fundamental quantity to constrain. However, estimates of atmospheric molecular nitrogen partial surface pressures (pN2) during the Archean widely vary in the literature. In this study, we apply a model combining newly-gained insights into atmospheric escape, magma ocean duration and outgassing evolution to derive pN2 during the Hadean and Archean. Results suggest
Photoevaporation of Water Dominated Exoplanet Atmospheres
Authors: Harbach Laura , Owen James , Mohanty Subhanjoy
Published: October 2020

The atmospheres of close-in, low-mass exoplanets are extremely vulnerable to the effects of stellar UV to X-ray radiation. Photoevaporation can significantly ablate planetary atmospheres or even strip them entirely, potentially rendering a planet inhabitable. Existing hydrodynamical studies of this important atmospheric mass loss mechanism have mainly considered hydrogen/helium dominated atmospheres. Currently, the effect of more complex chemistry on photoevaporative mass loss has only been the subject of a limited number of studies (e.g. Bolmont et al. 2017). In the era of more advanced exoplanet atmospheric observations, it is more important than ever to determine what, if any atmosphere, these planets may have been able to retain. Here, I present preliminary results of hydrodynamic simulations, showing how the atmosphere of a low-mass planet undergoing photoevaporation is affected by the inclusion of water.