bluuebunny/crossref_metadata_2025 huggingface dataset:
First Optical Constants from 0.4 to 1.6 µm of Titan Aerosol Analogs Produced in the NASA Ames COSmIC Facility and Their Use in a New Analysis of Cassini VIMS Observations
Authors: Sciamma-O'Brien Ella , Roush Ted , Rannou Pascal , Salama Farid
Published: September 2022

We have determined the real and imaginary refractive indices (n and k, respectively), from the visible to the near infrared (0.4 to 1.6 µm), of five laboratory-generated organic refractory materials produced from gas-phase chemistry with the NASA Ames COSmIC facility. The solid samples were produced using a plasma discharge in the stream of a 200-K supersonic jet-cooled expansion of different gas mixtures to study the impact of the molecular precursors on the solid sample optical properties. Three samples were produced from N2:CH4 (95:5) gas mixtures using three different high voltages (700V, 800V and 1000V) to vary the energy in the plasma discharge. One sample was produced from a N2:CH4:C2H2 (94:5:5:0.5) gas mixture, with a high voltage of 1000 V. The fifth sample was produced in an Ar:CH4 (95:5) gas mixture with a high voltage of 1000 V to produce a nitrogen-free hydrocarbon sample. The optical constants, n and k, of these five samples were determined using spectral reflectance measurements. They appear to be positively correlated with the nitrogen content in the solid sample, i.e., a sample with larger nitrogen content exhibits higher n and k values.

We have used these refractive indices as input parameters in a radiative transfer model to analyze Cassini Visible Infrared Mapping Spectrometer (VIMS) observations of Titan’s atmosphere. The results show that using the tholin samples with higher n and k values (higher nitrogen content) provides a better fit to the observational data than using the samples with lower n and k values (lower nitrogen content). The Titan tholins with higher nitrogen content therefore appear to be more representative of the Titan aerosols observed by VIMS.
Dynamical Investigation of Trans-Neptunian Objects in particular the Mean-Motion Resonances with Neptune
Authors: Forgács-Dajka Emese , Kővári Emese , Kovács Tamás , Kiss Csaba , Sándor Zsolt
Published: September 2022

There are a large number of small bodies (known as trans-Neptunian objects or TNOs) in the outer solar system that show different types of dynamical behavior. These objects can be considered as "probes" of the dynamical and chemical history of the Solar System. These asteroids or planetezimals are relics of dynamical events among and beyond the giant planets, and the current observed orbital distribution of the TNOs is a sign of large-scale changes in the position of the giant planets. The dynamical classification of the bodies of this outer region of the Solar System helps to understand the structure and formation of the Solar System. In this work, we performed a comprehensive survey on the TNOs. By using the FAIR method considering all known small bodies in outer Solar System (more than 4,000 asteroids classified as TNO in the JPL database), we identified several MMRs between these bodies and the planet Neptune. According to our dynamical investigations, there are two types of resonant behaviour of asteroids; namely, when the critical argument (resonance variable) shows short-term or long-term libration.
Fundraising for HEIs and scholars in Africa. The case of the Erasmus+ programme and other examples of funding opportunities
Authors: Mercatelli Livia
Published: September 2022

Funds are a key-factor to boost research capacity and development at institutional as well as individual level. As universities in emerging countries seek to expand their academic activities in the fields of education and research, the pressure to have financial resources constantly available is obviously intensifying. Back in 2015 in Dakar, at the African Higher Education Summit “Revitalizing Higher Education for Africa’s Future”, the African Union highlighted funding as one of the top five higher education priorities.

If mainstream resources and government funds are often deemed as insufficient, it is also true that many external donors - in the framework of their mission and policies - are investing in higher education development to support institutions and individuals through different funding schemes. Within the Africa-EU Partnership supported by the European Union and the African Union, for instance, higher education cooperation is pivotal for the cooperation goals of the Partnership. Indeed, the new EU-funded Erasmus+ programme has known a four-fold increase of budget allocation to external actions in Sub-Saharan Africa region, covering for the period 2021-2027 the 26% of budget dedicated to the international dimension of the programme. The programme will provide opportunities for collaborative partnerships of HEIs to innovate and modernise education and develop capacities but also for individual academic mobility.

Erasmus+ is one example, among others available, of an external opportunity to attract resources to African academic community which is not always aware this and other funding opportunities exist. The presentation will provide an overview of opportunities available under the Erasmus+ programme and beyond meant for collaborative projects and individual development.
Some technical challenges for parametrized one-dimensional thermal evolution models of Mercury
Authors: Knibbe Jurrien
Published: September 2022

One-dimensional parametrized planetary thermal evolution models are often used for computation of many thermal evolution schemes of a planet, as convenient alternative for computationally expensive thermal evolution simulations that solve complex three-dimensional processes, such as convective motions. Such one-dimensional thermal evolution models for terrestrial objects are motivated mainly with a silicate-dominated object in mind (Venus, Earth, the Moon, and Mars), with a small relative size of the metallic core. Because a correspondingly thick mantle commonly remains convective for a long period of time, parametrized mantle evolution models focus primarily on capturing the convective state of the thick mantle. Additionally, the thermal profile of the metallic core is commonly simplified by an adiabat, or the core is treated as a thermal load situated below the mantle. For a small core, this assumption goes without loss of much accuracy even if the core may actually end up (partly) conductive. Because the assumptions of a convective mantle and fully adiabatic or small core seem to be inappropriate for Mercury, we are developing a parametrized thermal evolution model for Mercury with a mantle and core that turns into a (partially) conductive state. The model development takes strict conservation of energy as starting point, which is an additional minor improvement relative to most existing parametrized thermal evolution models. I will present an outline of the developed model, and discuss some challenges for future work.
Dissemination of astrophysics from the IAA-CSIC on the internet: from dramatized video blogs to Twitch
Authors: García Gómez-Caro Emilio José
Published: September 2022

In the Scientific Culture Unit of the IAA-CSIC we work in different formats to bring astrophysics to society. In addition to more traditional formats, such as talks, articles, audiovisuals, etc., we also explore different channels and formats. In this section you will find especially a good part of our on-line disclosure. In this talk we will talk about some of these projects such as: video blogs ("The Teslablog" and "The strange case of Henrrieta Leavit and Erasmus Cefeido"); Webseries, such as "El Astrónomo Indignado" and "Camino a Congreso"; Videos for visually impaired people ("The Universe in Words"); Remote observations, such as the one made on the occasion of the Saturn-Jupiter conjunction, and the recent broadcast through a Twitch channel with an in-person audience. We will analyze the advantages and disadvantages of this channel for these projects, as well as the mistakes and successes that have been made in them.
First NGP measurements at Mercury
Authors: De Filippis Umberto , Lefevre Carlo , Lucchesi David , Lucente Marco , Magnafico Carmelo , Peron Roberto , Santoli Francesco
Published: September 2022

ISA (Italian Spring Accelerometer) is a scientific payload of the Mercury Planetary Orbiter (MPO) module of the ESA/JAXA BepiColombo mission to planet Mercury and it is the first high-sensitivity accelerometer on-board an interplanetary spacecraft. It will be one of the key instruments to perform Radio Science Experiments during the orbital phase. The instrument is sensitive to any acceleration, greater than 10-8 ms-2Hz-1/2, perturbing the free fall of the spacecraft in the overall gravity field. The main goal of ISA is indeed to measure the so-called Non Gravitational Perturbations (NGP) allowing to reconstruct, a posteriori, the motion of the spacecraft on a geodesic of spacetime. During the first Mercury flyby, performed in October 2021, the spacecraft approached the target planet reaching an altitude above its surface of only 200 km. Thanks to this very low altitude and to the ISA on-board position in cruise configuration, far away from the center of mass of the overall composite spacecraft, the accelerometer has been able to clearly detect the gravity gradient accelerations. Indeed, this is the first direct measurement of the gravity gradient acceleration induced on a spacecraft by the gravity field of a celestial object different from the Earth. Near the closest approach to the planet, the spacecraft entered in eclipse, losing the effect of the solar radiation pressure acting on its surfaces exposed to the Sun. As a consequence, a sudden change of the acceleration was clearly detected by the accelerometer; the measured signal has a magnitude aligned with the expectations, computed considering optical coefficients and spacecraft attitude. In June 2022, BepiColombo will carry out a second flyby that will be very similar, in terms of altitude, attitude and B-plane coordinates, to the first one, representing an almost unique opportunity to compare two similar measurements.
Thermal Condensation of Glycine and Alanine on Metal Ferrite Surface: Primitive Peptide Bond Formation Scenario
Authors: Jheeta Sohan
Published: September 2022

The amino acid condensation reaction on a heterogeneous mineral surface has been regarded as one of the important pathways for peptide bond formation. Keeping this in view, we have studied the oligomerization of the simple amino acids, glycine and alanine, on nickel ferrite (NiFe2O4), cobalt ferrite (CoFe2O4), copper ferrite (CuFe2O4), zinc ferrite (ZnFe2O4), and manganese ferrite (MnFe2O4) nanoparticles surfaces, in the temperature range from 50–120  oC for 1–35 days, without applying any wetting/drying cycles. Among the metal ferrites tested for their catalytic activity, NiFe2O4 produced the highest yield of products by oligomerizing glycine to the trimer level and alanine to the dimer level, whereas MnFe2O4 was the least efficient catalyst, producing the lowest yield of products, as well as shorter oligomers of amino acids under the same set of experimental conditions. It produced primarily diketopiperazine (Ala) with a trace amount of alanine dimer from alanine condensation, while glycine was oligomerized to the dimer level. The trend in product formation is in accordance with the surface area of the minerals used. A temperature as low as 50 oC can even favour peptide bond formation in the present study, which is important in the sense that the condensation process is highly feasible without any sort of localized heat that may originate from volcanoes or hydrothermal vents. However, at a high temperature of 120 oC, anhydrides of glycine and alanine formation are favoured, while the optimum temperature for the highest yield of product formation was found to be 90 oC.
The significance of intrusive volatile release for the Earth´s atmosphere.
Authors: Vulpius Sara , Noack Lena
Published: September 2022

After the solidification of the magma ocean, outgassing from the interior is the prevailing volatile source of Earth´s atmosphere. Besides the well-studied extrusive degassing, this process also includes the often neglected intrusive volatile release. Although, intrusive magma production rates are assumed to be significantly higher compared to extrusive rates. This renders the investigation and quantification of possible volatile exsolution mechanisms from intrusive magma bodies crucial.

An emplaced magma body progressively crystallizes due to cooling. The precipitation of certain minerals fractionates the primitive mantle over time by incorporation of compatible elements and molecules into the crystal lattice. In contrast, incompatible elements and molecules, including volatiles like H2O and CO2 are precluded from the crystal lattice due to their unsuitable ion radius or charge. Thus, ongoing crystallization likely leads to an oversaturation of volatiles in the remaining melt and an enhanced exsolution.

In our study, we simulate the partitioning, solubility and release of H2O and CO2 from a magma body emplaced at different depths within the lithosphere. Additionally, we take the possibility of melt ascent and the formation of hydrous minerals into account. According to our simulations the release of H2O and CO2 from an intrusive magma body is possible to a depth of at least 100 km (~3 GPa, which is comparable to the average thickness of the Earth's lithosphere). However, the release strongly depends on the initial volatile budget, the formation of hydrous phases, the depth of the intrusion and the buoyancy of the melt. Considering all these factors, our model suggests that about 0 - 85 % H2O and 100 % CO2 can be released from mafic intrusions. This renders the incorporation of intrusive volatile release mandatory in order to determine the volatile fluxes and the composition of Earth's atmosphere.
The B-star exoplanet abundance study (BEAST): at the frontier of planet formation
Authors: Squicciarini Vito
Published: September 2022

With a sample of 5000 objects at hand, exoplanet demographics is beginning to grasp key aspects of the physical mechanisms lurking beneath the multifaceted hues of the observed exoplanetary architectures. Ascertaining the dependence of planetary properties on stellar mass, and whether their very formation is possible even within the short-lived protoplanetary disks surrounding massive stars, compulsorily requires a complete and unbiased census of the exoplanet population. However, most exoplanet surveys have so far focused on stars not larger than the Sun, and 90% of known exoplanets are closer to their star than the Earth is to the Sun. This strong observational bias, connected to the preference of transits and radial velocities for close-in planets and low-mass stars, has recently started being alleviated by direct imaging, a technique that is instead preferentially sensitive to young giant planets in wide orbits. Radial velocity studies have found that the occurrence of giant planets is higher around more massive stars up to about 2 M_sun; an abrupt turnover is then observed, with the occurrence eventually falling to zero at M>3 M_sun. To clarify if this trend is real, or if a wide-orbit population of giant planets is escaping detection, we have started the B-star exoplanet abundance study (BEAST), a direct-imaging study based on the high-contrast capabilities of SPHERE@VLT. BEAST is looking for exoplanets around 85 B stars belonging to the young (5-30 Myr) Scorpius-Centaurus association. While the survey is still in progress, its early results -that I will show here- are already intriguing: even binary systems such as b Centauri (Janson et al. 2021), or stars doomed to explode as supernovae such as μ2 Scorpii (Squicciarini et al. 2022), can possess their planetary systems, challenging the predictions of conventional formation models.
Non-gravitational parameters of the comet 45P/Honda-Mrkos-Pajdusakova
Authors: Wlodarczyk Ireneusz
Published: September 2022

We present computations of orbital elements together with the non-gravitational parameters of comet 45P/Honda-Mrkos-Pajdusakova
 based on all published observations. We based our computation on all 3039 total published observations over intervals: 
 1949 01 09.54284 – 2017 05 27.52823:
 (https://minorplanetcenter.net/iau//mpc.html).
Table 1. Starting keplerian orbital elements and non-gravitational A1 and A2 computed for error model ‘vftc17’.

! Keplerian elements: a, e, i, long. node, arg. peric., mean anomaly
 a=3.02464146+/- 1.320E-05 au
e=0.8239397608+/- 7.194E-07  
i=4.248075506+/-   7.060E-06 deg
long. node=88.9836730+/- 2.339E-04 deg
arg. peric.=326.2795146+/- 2.306E-04  deg
mean anomaly=8.38189802+/-6.005E-05 deg
 Epoch: MJD57798.0 (2017-Feb.-14) TDT
 H=17.194

A1=(16.77E-10+/-1.06)E-10 au/day^2
A2=(-3.4150E-10+/- 0.0019)E-10 au/day^2
Earth MOID=0.06027 au
Asc. node-Earth separation=-0.40698 au
Desc. node-Earth separation=2.07196 au
RMS=1.446",                  

where A1 – non-gravitational radial acceleration parameter, A2 – non-gravitational transverse accelaration parameter.
To compute the above non-gravitational parameters, we used the publicly available OrbFit v.5.0.7 software. We used the error ‘vftc17’ model according to [1].
We used the JPL DE431 Solar System model with an additional 17 massive asteroids as described in [2] and [3].

Acknowledgments: We want to thank the Space Research Center of the Polish Academy of Sciences in Warsaw for the possibility of working on a computer cluster.

References: 
[1] Veres P. et al. (2017), Icarus, 296, 139. [2] del Vigna et al. (2018)  A&A, 617, A61. [3] Farnocchia, D. (2013), Icarus, 224,1.

 

 

 

 

 

 

 

 

 
Palaeoclimate of Titan with methane oceans and continents simulated by a global climate model
Authors: Tokano Tetsuya
Published: September 2022

The limited photochemical lifetime of methane in Titan’s atmosphere and the lack of obvious strong methane sources at present allow the idea that Titan experienced past epochs in which the total inventory of outgassed methane was much larger than today. Much of the methane inventory would have existed as surface oceans because the atmospheric methane content is limited by condensation. The observed topography and estimated evolution of the methane inventory imply that a combination of oceans and continents as on Earth was more likely than a global ocean within the past 1 Gyr. Titan’s palaeoclimate in the presence of hypothetical methane-rich oceans and continents is simulated in an exemplary way by a global climate model coupled to a slab ocean model. The model also takes into account the exchange of N2 between the ocean and atmosphere as the N2 solubility in the ocean changes with the ocean temperature. If the ocean is global and there are no continents, the tropospheric climate is globally very moist but calm. N2 is released from the ocean in spring and is absorbed by the ocean in autumn. The global imbalance between the N2 release and absorption causes a semi-annual oscillation of global-mean surface pressure by 0.1 hPa, by analogy with the semi-annual oscillation of surface pressure on Mars caused by the polar CO2 condensation and sublimation. In warm seasons, oceans are colder than continents because of evaporative cooling of the ocean. The ocean-land temperature contrast in warm seasons induces a sea breeze circulation, which carries moist air onshore and thereby causes substantial orographic rainfall in coastal areas and elevated terrains of continents. Therefore, the total precipitation is larger on continents than over oceans regardless of the geographic location of continents. This may have implications for the geomorphology. For instance, the possible presence of circum-Xanadu ridges surrounded by methane-rich oceans may have been conducive to substantial seasonal rainfall around Xanadu, which partly drained to the desiccated Xanadu basin and caused the formation of the observed numerous fluvial networks.

 
Results from the professional-amateur collaboration to investigate the Cloud Discontinuity phenomenon in Venus’ atmosphere
Authors: Kardasis Emmanouil , Peralta Javier , Maravelias Grigoris , Imai Masataka , Wesley Anthony , Olivetti Tiziano , Naryzhniy Yaroslav , Morrone Luigi , Gallardo Antonio , Calapai Giovanni , Camarena Joaquin , Casquinha Paulo , Kananovich Dzmitry , MacNeill Niall , Viladrich Christian , Takoudi Alexia
Published: September 2022

The cloud discontinuity of Venus is a planetary-scale phenomenon known to be recurrent since, at least, the 1980s. It was initially identified in images from JAXA’s orbiter Akatsuki.  This disruption is associated to dramatic changes in the clouds’ opacity and distribution of aerosols and is interpreted as a new type of Kelvin wave. The phenomenon may constitute a critical piece for our understanding of the thermal balance and atmospheric circulation of Venus. The  reappearance on the dayside middle clouds  four years after its last detection with Akatsuki/IR1 is reported in this work. We characterize its main properties using exclusively near-infrared images from amateur observations for the first time. The discontinuity exhibited tempοrаl variations in its zonal speed, orientation, length, and its effect over the clouds’ albedo during the 2019/2020 eastern elongation in agreement with previous rеρorts. Moreover, amateur observations are compared with simultaneous observations by Akatsuki UVI and LIR confirming that the discontinuity is not visible on the upper clouds’ albedo or thermal emission. While its zonal speeds are faster than the background winds at the middle clouds, and slower than winds at the clouds’ top, it is evidencing that this Kelvin wave might be transporting momentum up to upper clouds.
Exploring the recycling model of Phobos formation: rubble-pile satellites
Authors: Madeira Gustavo , Charnoz Sebastien
Published: September 2022

Phobos is the target of the return sample mission Martian Moons eXploration that will provide a better understanding of the satellite's composition, giving clues about its formation. Some models propose that Phobos and Deimos were formed after a giant impact forming an extended debris disk.  Assuming that Phobos and it parents bodies have a low material cohesion Hesselbrock and Milton (2017) have showed that a "recycling process" may happen during the assembling of Phobos, by which Phobos' parents are destroyed into a Roche-interior ring and reaccreted several times. We explore in details the recycling model, and pay particular attention to the characteristics of the disk using 1D models of disk/satellite interactions. In agreement with previous studies we confirm that , if Phobos' parents bodies are indeed rubble piles, then the recycling process do occurs. However, Phobos should be accompanied today by a Roche-interior ring which characteristics are not reconcilable with today observations of Mars' environment. Indeed a residual ring should exist in addition to Phobos, that is not observed. Thus we conclude that, if Phobos formed in a giant impact, its parent bodies should have been cohesive and there was never a recycling process. In this hypothesis, Phobos is the last object of and old moonlets population that migrated toward and  crashed onto Mars. Alternatively, if Phobos' parent bodies were cohesive-less, then we do find one solution: the giant impact should have happened recently (<2 Gyrs ago) and that a Mars ring should exist today with optical depth 1e-5 with particle size about a few meters size. 
How do Mercury's planetary magnetic field models compare to measurements from MESSENGER's and BepiColombo’s first flybys?
Authors: Exner Willi , Griton Léa , Heyner Daniel
Published: September 2022

Due to limited spacecraft coverage, the planetary magnetic field of Mercury was well observed only in the northern magnetosphere by the MESSENGER mission.
Multiple inversion methods have been applied to observational data to determine planetary magnetic field models that, each, identify a northward planetary magnetic equator offset but differ in the resulting multipole moments.
In the forward-modeling approach of this study, we take three different planetary magnetic field model representatives and model the resulting solar wind interaction with sets of the 8 most common interplanetary magnetic field (IMF) directions under otherwise nominal solar wind conditions.
We then extract the modeled magnetic fields along flyby trajectories of MESSENGER and BepiColombo that have their closest approach in the nightside regions of the southern magnetosphere.
By using both, MHD and hybrid models, we conclude that in these specific regions, the influence of the upstream IMF is minimal and is therefore uniquely suited to discriminate the influence of the different internal planetary magnetic field models.
Comparing these results with MESSENGER and BepiColombo flyby observations, we find which model is better suited to fit the observations.
Estimations of Ion Escape from Mars
Authors: Holmstrom Mats , Zhang Qi , Wang Xiao-Dong , Fatemi Shahab
Published: September 2022

We estimate ion escape from Mars by combining observations and models. Assuming that upstream solar wind conditions are known, a computer model of the interaction between the solar wind and the planet is executed for different ionospheric ion production rates. This results in different amounts of mass loading of the solar wind. Then we obtain the ion escape rate from the model run that best fit observations of the bow shock location. This method enables studies of how escape depend on different parameters, and also escape rates during extreme solar wind conditions, applicable to studies of escape in the early solar system, and at exoplanets. This approach also allows us to use data sets traditionally not used for ion escape estimates, such as magnetic field and electron observations. We can also estimate the escape rate from a very small set of observations, during every orbit of a spacecraft around a planet or during one flyby of a planet.
A journey to the Interior of (ultra-short-period) Earths
Authors: Kervazo Mathilde , Bourrier Vincent , Egger Jo Ann , Alibert Yann
Published: September 2022

Half of known exoplanets orbit close to their star, featuring a desert of hot Neptunes whose origins remain uncertain. The lower border of the desert ends in a population of small rocky planets (≤ 2 R⊕) on ultra-short periods (≤ 1 day) called USPs. These USPs are central to study planetary evolution around the desert, as they might be the exposed rocky cores of evaporated gaseous planets. Due to their proximity to the star, the surface temperature of USPs are expected to be higher than the melting point of most rock-forming minerals. Their likely molten unstable surface, which could lead to significant outgassing from magma oceans or active volcanoes, and the formation of a dust- and metal-rich envelope, would significantly affect the composition of the outer enveloppe. There is thus a need in characterising the internal structure of planets subjected to such extreme conditions.

Most studies concerned with interior characterization have generally concentrated on computing mass-radius relations based on terrestrial-type interior structures and compositions. Such “forward” approaches, however, allow for different core sizes and mantle compositions, affecting the mass-radius relationship, and do not quantify the inherent degeneracy of interior structure models. In the light of this inherent ambiguity, some studies propose a complete Bayesian inverse analysis by employing a Markov chain Monte Carlo method to provide full probability distributions for the model parameters of interest.  Moreover, a layered structure is classically considered, with, from the centrer to the surface, a metallic core, a rocky mantle, a water layer and an outer enveloppe composed of hydrogen and helium. This classical composition might be questioned in the particular case of the USPs, especially for their enveloppe part, for which the metallicity might vary due to compositional differences.

In this context, the goal of our study is to develop a coherent internal structure model for the specific USP population and to derive samples of properties on their internal structure, by performing a statistical method which allows to characterize an exoplanet’s interior given its mass and radius. For that purpose, we use the simulation code call the Bayesian Interior Characterisation of ExoPlanetS (BICEPS) model, and adapt it to USPs in order to better understand the formation and evolution of short-period planets, in particular the atmospheric erosion, under strong stellar irradiation, characteristics of USPs.

Acknowledgements: This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (project Spice Dune, grant agreement No 947634).
MAVEN observations of initial ion acceleration in the Martian ionosphere
Authors: Hanley Gwen , Fowler Christopher , McFadden James , Mitchell David , Curry Shannon
Published: September 2022

Though ion escape to space is an important mechanism for atmospheric loss on Mars, the processes that accelerate ions to escape velocity have not been identifed and quantified. The lowest altitude where suprathermal planetary ions appear is an important source region for ion escape, where electromagnetic forces and waves begin to energize ions to escape velocity. We have conducted a statistical study of O2+ distribution functions measured by Mars Volatile EvolutioN SupraThermal And Thermal Ion Composition (MAVEN-STATIC) in order to identify this source region for Martian ion escape. We have fit Maxwellians to each measured O2+ distribution function in order to identify distributions containing a suprathermal component. Suprathermal ions appear just above the exobase region at all solar zenith angles, but Maxwellian ion distributions persist to higher altitudes near the terminator than on the dayside or the nightside. We also investigated the effects of crustal magnetism, finding that crustal fields protect planetary plasma from energization on the dayside and enhance energization on the nightside.
The interior diversity of terrestrial-type exoplanets: constrained with devolatilized stellar abundances and mass-radius measurements
Authors: Wang Haiyang , Quanz Sascha , Yong David , Liu Fan , Seidler Fabian , Acuna Lorena , Mojzsis Stephen
Published: September 2022

A major goal in the discovery and characterization of exoplanets is to identify terrestrial-type worlds that are similar to (or otherwise distinct from) our Earth. The combination of mass-radius measurements and host stellar abundances has been proposed to constrain the interiors of small (rocky) exoplanets. In this work, we advocate the importance of using devolatilized stellar abundances, instead of uncorrected stellar abundances, to further reduce degeneracies in modelling the interiors of rocky exoplanets. We apply an empirical devolatilization model to a selected sample of 13 planet-hosting Sun-like stars, for which high-precision photospheric abundances have been available. With the resultant devolatilized stellar composition (i.e. the model planetary bulk composition), as well as other constraints including mass and radius, we model the detailed mineralogy and interior structure of hypothetical, habitable-zone terrestrial planets (‘exo-Earths’) around these stars. Model output shows that most of these exo-Earths are expected to have broadly Earth-like composition and interior structure, consistent with conclusions derived independently from analysis of polluted white dwarfs. Investigating the empirical devolatilization model at its extremes as well as varying planetary mass and radius (within the terrestrial regime) reveals potential diversities in the interiors of terrestrial planets. By considering (i) high-precision stellar abundances, (ii) devolatilization, and (iii) planetary mass and radius holistically, this work represents essential steps to explore the detailed mineralogy and interior structure of terrestrial-type exoplanets, which in turn are fundamental for a quantitative understanding of planetary long-term evolution including the interior-atmosphere interactions.
Pitch angle distributions (PADs) near the Galilean moons of Jupiter: Galileo flybys revisited
Authors: Krupp Norbert , Roussos Elias , Kollmann Peter , Paranicas Chris , Clark George , Khurana Krishan
Published: September 2022

Pitch angle distribution of energetic particles can be used to understand the global topology of field lines (connected on both ends to the planet, connected on both ends to the moon or connected on one end to the moon and the other end to the planet etc.). The pitch angle distributions on field lines connected on one end to the moon can also be used to gauge the speed at which the field lines are convecting past a moon.

The Galileo spacecraft flew by the Galilean moons multiple times and explored the charged particle distributions in their vicinities. In this paper we will revisit the data of the Energetic Particles Detector EPD onboard Galileo in terms of pitch angle distributions for various energy channels  for different ion species and electrons in the energy range from 15 keV up to several tens of MeV.

We analyzed the Europa flybys E11, E12, E14, E15, E26.; Ganymede flybys G2, G7, G8, G28, G29; Callisto flybys C3, C9, C10.

We will show how different the energy-dependent pitch angle distributions are upstream and downstream of the moons and how different those distributions are between electrons and the various ions.

Electron PADs near Europa are trapped for energies of several 100 keV while for lower energies the PAD shapes are uncertain. Dropout signatures indicate that charged particles are lost in the moons' tenuous exospheres and onto their surface.

PADs near Ganymede showed bi-directional electron distributions for low energies upstream and trapped for higher energies while PADs of protons and heavy ions are more isotropic. Inside Ganymede’s magnetosphere trapped distributions have been observed when the S/C was connected to closed field lines.

The signal-to-noise ratio of energetic electron and ion fluxes near Callisto is a factor of 10 lower than for Europa. PADs near the moon are less clear compared to the other Galilean satellites. Bi-directional ion PADs close to the moon have been observed.
Rotational properties of MB family asteroids, Hildas, and Trojans, based on K2 and TESS observations
Authors: Szabó Gyula
Published: September 2022

Our understanding of Solar System family asteroids has been significantly widened by space surveys primarily targeted to exoplanet detections. In K2 and TESS fields, many asteroids passed through, being a basis of continuous sateroid photometry covering several basis. This enabled the proof
of the high fraction of slow rotators (period>30 hours) in asteroid families (30%), non-family MB asteroids (35%), the Hilda group (39%) and the Trojan swarms (25%). High ratio of extremely slow rotators (P > 100 hr) in the Hilda group is (18%) is unique in the Solar System. 

We found a family-specific amplitude and/or period distribution only in some asteroid families (Hungaria, Maria, Juno, Eos, Eucharis, and Alauda). Older families tend to contain a larger fraction of more spheroidal, low-amplitude asteroids. The rotation period distributions are different in the cores and outskirts of the Flora and Maria families, while the Vesta, Eos, and Eunomia families lack this feature. We also confirm that very fast spinning 
asteroids are close to spherical (or spinning top shapes), and minor planets rotating slower than ≈11 h are also more spherical than asteroids in the 4-8 h period range and this group is expected to contain the most elongated bodies. 

Despite a previously suggested mixed origin of Hildas from the MB and the Trojan swarms, we revealed no differences in the photometric properties between the taxonomically different R and LR Hildas: the entire Hilda group highly resembles the Trojans for rotational properties. 
Inferring characteristics of the young planet population from high resolution protoplanetary disk imaging
Authors: Huang Jane
Published: September 2022

High angular resolution observations of protoplanetary disks at millimeter and near-infrared wavelengths have revealed an impressive variety of substructures, including gaps and rings, spiral arms, warps, and asymmetries. Models have suggested that many of these structures can be produced through planet-disk interactions. These substructures can therefore open a window into the properties of protoplanets that are below the limits of what current direct imaging technology can probe. I will review recent observations of disk substructures and how they have been used to infer the masses and orbital properties of embedded protoplanets. I will also comment on alternative interpretations of these disk substructures and what future observations will help to break degeneracies. 
MARCOT: A new approach to a large aperture telescope with a novel multimode photonic lantern
Authors: Amado Pedro , Aceituno Jesus , Pozuelos Francisco , Ortíz Jose Luis
Published: September 2022

In the past half-century, a new generation of successively ever larger and more sophisticated telescopes and instruments have ushered in a golden age of remarkable results in astronomy. This road is taking us to the age of the extremely large telescopes (ELTs). Riding on this wave and contributing to it is exoplanet research. We are characterising the orbit and mass of exoplanets with Doppler measurements which, combined with the transit technique provide estimates of bulk densities and compositions. The picture is completed with upcoming space missions such as ARIEL or PLATO. To prepare the road into this new era, we propose to build the MultiArray of Combined Telescope (MARCOT). This large aperture telescope consists of multiple identical low-cost telescopes, at a fraction of the cost of building an ELT. We propose MARCOT to support science cases, such as time-domain astronomy in general and exoplanet research in particular, that are too expensive or impractical to conduct on ELTs. MARCOT will be linked through optical fibres combined by a novel Multi-Mode Photonic Lantern (MM-PL) into a MM fibre that will feed a single high-resolution echelle spectrograph, optimized for extreme-precision radial velocity measurements. We will present the status of the project focusing on the work carried out towards the conceptual design and the prototype of MARCOT, which is being built at the CAHA Observatory (Almeria, Spain), to feed the CARMENES spectrograph.
How many forming planets in the transitional disk around AB Aurigae ?
Authors: Di Folco Emmanuel , Boccaletti Anthony , Dutrey Anne , Tang Ya-Wen , Guilloteau Stephane , Pantin Eric
Published: September 2022

AB Aur is a bright and young Herbig Ae star surrounded by a broad transitional disk, with a long record of detailed observations at various wavelengths. Multiple direct and indirect evidences for the presence of embedded proto-planets have been reported in the recent years in this system. A prominent double spiral pattern was first detected with ALMA in the molecular line emission of CO gas, with a large pitch angle in the most inner region, suggesting the presence of at least one sub-stellar body within the cavity of the dusty disk (R<120au). We obtained two epochs of observations of AB Aur with VLT/SPHERE (Dec. 2019 - Jan. 2022). The first polarimetric image showed a wealth of structures at several scales. Two spirals clearly overlap those detected with ALMA, although with a higher angular resolution. One of these spirals features a twist located at 0.18’’ from the star, reminiscent of structures predicted by the theory of density waves produced by a gravitational perturber onto the gas distribution. The analysis of the multi-epoch data shows changes consistent with Keplerian rotation with a protoplanet located at about 30au from the star. In addition, localized emissions could be attributed to additional planet candidates (which are otherwise expected in order to carve the large disk cavity), including the recent claim of a super-Jupiter near 90au from high-contrast near-IR imaging with Subaru-SCexAO. All these pieces of evidence make AB Aur one of the most promising young sources to investigate planet-disk interactions, and to unveil the close environment of accreting planets. I will report on the global (and detailed) analysis of the new observational results for this nascent planetary system, both in the context of the multi-epoch, and multi-wavelength SPHERE+ALMA images, and with the contribution of multi-fluid hydrodynamical simulations. 
CoPhyLab Cryogenic Granular Sample Production, Storage and Quantification
Authors: Kreuzig Christopher , Bischoff Dorothea , Molinski Noah Samuel , Kovalev Alexander , Gorb Stanislav N. , Gundlach Bastian , Blum Jürgen
Published: September 2022

One of the most important analogue materials for comet simulation experiments are micrometer-sized water ice particles. In the framework of the CoPhyLab project we developed a system to produce and to securely store this material in large amounts for laboratory experiments.

First, the ice is produced by spraying micrometer-sized water ice droplets into liquid nitrogen. This is achieved by using a piezo nebulizer placed in distilled water. The vibration of the piezo leads to the formation of a cloud of micrometer-sized water droplet. A gas stream is used to push the droplets into a dewar, filled with liquid nitrogen, where the particles freeze. This procedure leads to the formation of the micrometer-sized ice particles. The filling height inside the dewar is controlled by a valve system and hence the machine can run automatically. The production rate of the ice producer is ~200 g of ice per hour.

Second, the liquid nitrogen must be removed while the ice remains cold to avoid sintering. Therefore, the mixture is placed in a cooled stainless-steel tube, which is placed in a cryogenic desiccator. The desiccator is a cylindrical vacuum chamber with a cooling system inside, which keeps the stainless-steel tube below 110 K. The nitrogen is removed by evacuating the chamber to a pressure of 10-6 mbar while constantly stirring the mixture. The result is a dry water ice powder composed of the individual micrometer-sized particles. The consistency of this ice can be described as powdered sugar. After the ice is dried it can be stored inside the desiccator or in cryogenic transport canes, which enables the transport even by plane to other laboratories.

The ice particles were investigated with a cryogenically cooled scanning electron microscope at the Christian-Albrechts-University in Kiel. The results are showing that the ice is not altered at any point of the production process or during storage. The mean radius of the particles is 2.4 micrometer and 80 % of the particles are between 1.5 micrometer and 3.5 micrometer.
Melting probe - thermomechanical modeling of descent rate
Authors: Malík Jiří , Souček Ondřej
Published: September 2022

Melting probe is an autonomous exploratory tool that uses heat, typically generated by a nuclear energy source, to penetrate through layers of ice. Working devices have been used in terrestrial conditions for some time, but the concept has a potential for space missions, especially those that aim to collect water samples from subsurface oceans on icy moons. This motivates computational study of the concept, one that could answer fundamental questions regarding time and power requirements of the melting probe mission.
In this talk, which presents results obtained in collaboration with Ondřej Souček, a multi-physics modelling approach will be introduced. The model couples a mechanical problem, governed by the Navier-Stokes equations with temperature dependent material properties, together with a thermal problem, in the form of a non-linear heat equation reformulated in enthalpy that is capable of capturing the phase-change phenomena. Though complex, the versatility of such model enables a study of the fully-convective regime of the melting probe. Preliminary results show that the coupled problem formulated in the axisymmetric two-dimensional approximation is (computationally) tractable and, at the same time, estimates the rate of ice penetration based on the external conditions, i.e., ice temperature and viscosity, gravitational acceleration, etc. The results form a foundation for possible kinematic models of ice sheet penetration that lead to estimates of mission time requirements.
So far, the problem was studied in the simple setting of a heated sphere with a fixed frame of reference (see Fig.1, Fig.2 for preliminary results of a test setting). The solution is approximated by the finite element method implemented within the FEniCS computational platform.
This stage, which serves as the model's proof of concept, permits straightforward generalizations (e.g., realistic cylindrical geometries, water jets boundary conditions, Arbitrary Lagrangian–Eulerian kinematic description). A brief discussion of the extensions will demonstrate the utility of the model.

Acknowledgement: The authors would like to express their gratitude toward Charles University Grant Agency, project GA UK n. 1062120 (J.M.) and Czech Science Foundation, project 22-20388S (O.S.).

Figure 1. Preliminary results - three time stamps show the evolution of temperature (including melting temperature isotherm), dynamic viscosity, and velocity field around the heated sphere (test problem parameters setting).

 

Figure 2. Preliminary results - time evolution of probe descent velocity
Four candidate landing sites at the southern lunar polar region to drill water ice using solar powered missions
Authors: Kereszturi Akos , Boazman Sarah , Heather David , Tomka Richard , Warren Tristam
Published: September 2022

The evaluation of candidate landing sites for a solar powered ice drilling mission for the Moon was done at the southern polar region. Selection criteria were low slope angle surface, occasionally solar illuminated location with direct Earth radio access, together with <125 K temperature at 1 m depth. The survey showed thee-four areas where all of these needs were satisfied at sites close to each other (see the Figuew 1 below). Considering these regions, the maximal diameter for safe and scientifically relevant landing ellipse sizes are around 0.5-1 km diameter, while containing <20% of unfavourable locations can be larger around 2-4 km. The best location is around -27.03 W -86.75 S, where solar illumination can have 30% of time at least and WEH values are elevated. 

 

Figure 1. Insets of magnified versions of the four candidate areas.