bluuebunny/crossref_metadata_2025 huggingface dataset:
Asteroids orbit determination using INPOP19a adjusted on GAIA observations: strategy and validation.
Authors: Deram Pierre , Fienga Agnès , Gastineau Mickaël
Published: October 2020

Since December 2013, the GAIA spacecraft (ESA) is observing the sky with an unprecedented accuracy. Gaia DR2, released in April 2018, contains the position and epoch of 14099 known solar system objects (SSOs) representing more than 2 million observations collected during the first 22 months of operation. In this presentation, we used the new released INPOP19a planetary ephemerides to perform their orbital adjustment and compare them to radar and optical ground-based observations. In order to reduce the time of computation and in anticipation of the huge amount of datas expected with future DR3, a specific solving strategy for the normal equations of the Gauss-Newton algorithm is presented, making the best use of the model design. We obtain post-fit residuals that are closed to the expected performance of GAIA and overall consistent with the values announced by the DR2 reference orbit determination (see Gaia Collaboration et al 2018). In order to disccus the reliability of the obtained orbits, a combination with radar and optical ground based observations was performed for 23 objects using two different numerical methods: a systematic exploration of the weighting scheme coupled with a residual post-fit analysis, and a Least Square Variance Component Estimation adjustment algorithm (LSVCE). Such methods can be extended to all inverse problems within the framework of least-square formalism.
Earliest isotopic and chemical bifurcation of planetary building blocks
Authors: Lichtenberg Tim , Dra̧żkowska Joanna , Schönbächler Maria , Golabek Gregor J. , Hands Thomas O.
Published: October 2020

Recent astronomical (1,2) and geochemical (3,4) evidence point to early spatial and temporal fragmentation of the planet formation process, whose physical origins remain disputed. Here, using a coupled numerical model, we investigate the influence of the build-up of the solar protoplanetary disk (5) on the timing and internal evolution (6) of forming protoplanets. We find that the orbital drift of the water iceline can generate two temporally and spatially distinct  bursts of planetesimal formation, which sample different source regions of interstellar materials and experience limited intermixture. Driven by internal radiogenic heating, these planetary reservoirs compositionally evolve in two modes and recover accretion chronology, thermo-chemical pattern, and mass divergence of inner and outer Solar System. Our numerical experiments suggest that the earliest interplay between disk physics and geophysical evolution of accreting planetesimals initiated the present-day observed chemical and isotopic dichotomy of the Solar System planets. Figure caption: Schematic illustration of early Solar System accretion chronology suggested by our numerical experiments. Isotope variability (left) across the disk due to varying composition of infall material is retained by the traffic-jam of inward-drifting dust grains at the water iceline. The formation of two distinct planetesimal populations initiates divergent evolutionary pathways of inner and outer Solar System (right) due to the combined effects of internal radiogenic heating and secular variation of the dominant mode of planetary growth. References
Observations of Short Large Amplitude Magnetic Structures at the Kronian bow shock
Authors: Bebesi Zsofia , Erdos Geza , Dosa Melinda , Juhasz Antal , Szego Karoly
Published: October 2020

We observed Short Large Amplitude Magnetic Structures (SLAMS) at Saturn upstream of the quasi-parallel bow shock. Cassini surveyed the quasi-parallel regime mainly during 2004 and 2005, and we present a few detailed case studies from this time interval. For our analysis we used the measurements of the Cassini Plasma Spectrometer and the Magnetometer.Locally the SLAMS act as fast mode shock waves, and we observed ion beam reflection, multiple beams, deceleration and plasma heating of the solar wind protons. These features are in agreement with the near Earth observations of SLAMS. We also detected whistler precursor waves multiple times, which was also documented in studies of the Earth's foreshock region. Since the frequency of the upstream ULF waves observed at Saturn is lower than it is at Earth, it also has an effect on the spatial extension of the SLAM structures, which arise from these waves. With only one spacecraft's measurements it is not possible to study the SLAMS with the same efficiency as with the four-point measurements of the CLUSTER probes, but the basic observational features and the description of their evolutional characteristics are summarized. 
Sun Planet Interactions Digital Environment on Request (SPIDER) for Europlanet RI H2024
Authors: André Nicolas , Génot Vincent , Opitz Andrea , Cecconi Baptiste , Achilleos Nick , Guio Patrick , Milillo Anna , Mura Alessandro , Futaana Yoshifumi , Hess Sébastien
Published: October 2020

The H2020 Europlanet-2020 programme, which ended on Aug 31st, 2019, included an activity called PSWS (Planetary Space Weather Services), which provided 12 services distributed over four different domains (A. Prediction, B. Detection, C. Modelling, D. Alerts) and accessed through the PSWS portal (http://planetaryspaceweather-europlanet.irap.omp.eu/):A1. 1D MHD Solar Wind Prediction Tool – HELIOPROPA,A2. Propagation Tool,A3. Meteor showers,A4. Cometary tail crossings – TAILCATCHER,B1. Lunar impacts – ALFIE,B2. Giant planet fireballs – DeTeCt3.1,B3. Cometary tails – WINDSOCKS,C1. Earth, Mars, Venus, Jupiter coupling- TRANSPLANET,C2. Mars radiation environment – RADMAREE,C3. Giant planet magnetodiscs – MAGNETODISC,C4. Jupiter’s thermosphere, D. Alerts.In the framework of the starting Europlanet-2024 programme, SPIDER will extend PSWS domains (A. Prediction, C. Modelling, E. Databases) services and give the European planetary scientists, space agencies and industries access to 6 unique, publicly available and sophisticated services in order to model planetary environments and solar wind interactions through the deployment of a dedicated run on request infrastructure and associated databases.C5. A service for runs on request of models of Jupiter’s moon exospheres as well as the exosphere of Mercury,C6. A service to connect the open-source Spacecraft-Plasma Interaction Software (SPIS) software with models of space environments in order to compute the effect of spacecraft potential on scientific instruments onboard space missions. Pre-configured simulations will be made for Bepi-Colombo and JUICE missions,C7. A service for runs on request of particle tracing models in planetary magnetospheres,E1. A database of the high-energy particle flux proxy at Mars, Venus and comet 67P using background counts observed in the data obtained by the plasma instruments onboard Mars Express (operational from 2003), Venus Express (2006–2014), and Rosetta (2014–2015);E2. A simulation database for Mercury and Jupiter’s moons magnetospheres and link them with prediction of the solar wind parameters from Europlanet-RI H2020 PSWS services.A1. An extension of the Europlanet-RI H2020 PSWS Heliopropa service in order to ingest new observations from Solar missions like the ESA Solar Orbiter or NASA Solar Parker Probe missions and use them as input parameters for solar wind prediction;These developments will be discussed in the presentation.The Europlanet 2020 Research Infrastructure project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 654208.The Europlanet 2024 Research Infrastructure project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 871149.
Energetic proton depletions near Europa: plumes, atmospheric charge exchange and Alfvén wings
Authors: Huybrighs Hans , Blöcker Aljona , Roussos Elias , van Buchem Christiaan , Krupp Norbert , Futaana Yoshifumi , Barabash Stas , Holmberg Mika , Witasse Olivier
Published: October 2020

The flux of energetic protons (80 keV-1.04 MeV) near the Galilean moons was measured by the Energetic Particle Detector (EPD) on the Galileo mission (1995 - 2003). Near Galilean moons (such as Io and Europa) depletions of the energetic ion flux, of several orders of magnitude, were observed (see Figure 1).Such energetic ion depletions can be caused by the precipitation of these particles onto the moon’s surface or charge exchange with the neutral atmosphere. In addition, a magnetic field gradient can restrict access of the ions to certain regions, creating a “forbidden region.” To interpret the depletion features in the EPD data, a Monte Carlo particle tracing code has been developed. The expected flux of the energetic ions is simulated under different scenarios including those with and without an atmosphere, plume or inhomogeneous electromagnetic field.  By comparing the simulated distribution to the EPD data, the cause of the depletion features can be investigated. We identify the following causes of energetic proton depletions near Europa:Depletions are consistent with plumes during the flybys E12 and E26. These plumes coincide with the source location of Jia et al., 2018 and Arnold et al., 2019.
Depletions are consistent with atmospheric charge exchange during the flyby E26
Depletions coincide with Europa’s Alfvén wing during the flybys E17 and E25A. The Alfvén wings are two cylindrical regions extending to the north and south of Europa in which the low-energy plasma and the magnetic field are modified compared to the upstream conditions.
Furthermore, we investigate the effect of varying the atmospheric properties (scale height, density, presence of a sputtered component) and plume properties (density, location) on the depletions. Figure 1: Normalized flux of H+ (220 to 550 keV)  during the Galileo flybys of Europa. Depletions shown as darker colors.
The long-term cooling of the upper atmosphere of Uranus
Authors: Melin Henrik , Fletcher Leigh , Stallard Tom , Trafton Larry , Thomas Emma , Moore Luke , Chowdhury Nahid , O'Donoghue James
Published: October 2020

Abstract This molecular ion H3+ provides a really powerful tool with which we can remotely measure the ionospheric density and thermospheric temperature of the gas giants using near-infrared ground-based telescopes. These measurements show that the upper atmosphere of all four giant planets in our solar system are much hotter than solar input along can produce - this is known as the ‘energy crisis’ - and it is currently unclear from where this additional energy is sourced from. The two major candidates are the re-distribution of auroral Joule heating and the breaking of gravity waves generated in the turbulent lower atmosphere. Emission from H3+ has been observed from Uranus on a semi-regular intervals since 1992. We have previously shown that the upper atmosphere is subject to a remarkable long-term cooling, and has cooled from ~750 K in 1992 to 500 K in 2018, at a rate of ~8 K/year. This has important implications for the drivers of the elevated temperatures in the upper atmosphere, and may be related to the ever changing geometry between the offset magnetic field of Uranus the incoming  solar-wind. Here, we present the latest observations of H3+ emission from Uranus, obtained using the iSHELL instrument at the NASA Infrared Telescope Facility (IRTF) in October and November 2019. We explore any potential changes in the observed cooling, and discuss how these new observations fit within our current theories  of how the upper atmosphere of Uranus is heated.   Figure 1: The long-term temperature (a) and density (b) evolution of the upper atmosphere of Uranus between 1992 and 2018.  
Solar wind proton precipitation to the surface of Mercury
Authors: Fatemi Shahab , Poppe Andrew R. , Barabash Stas
Published: October 2020

We examine the effects of the interplanetary magnetic field (IMF) orientation and solar wind dynamic pressure on the solar wind proton precipitation to the surface of Mercury. We use the Amitis model, a three-dimensional GPU-based hybrid model of plasma (particle ions and fluid electrons), and explain a method we found necessary to accurately calculate plasma precipitation to the surface of Mercury through the highly dynamic Hermean magnetosphere. We use our model to explain ground-based telescope observations of Mercury's neutral sodium exosphere, and compare our simulation results with MESSENGER observations. For the typical solar wind dynamic pressure near the orbit of Mercury (i.e., ~7-8 nPa) our model shows a high solar wind proton flux precipitates through the magnetospheric cusps to the high latitudes on both hemispheres on the dayside with a higher precipitation rate to the southern hemisphere compared to the north, which is associated with the northward displacement of Mercury's intrinsic magnetic dipole. We show that this two peak pattern, which is also a common feature observed for neutral sodium exosphere, is controlled by the radial component (Bx) of the IMF and not the Bz component. Our model also suggests that the southward IMF and its associated magnetic reconnection do not play a major role in controlling plasma precipitation to the surface of Mercury through the magnetospheric cusps, in agreement with MESSENGER observations that show that, unlike the Earth, there is almost no dependence between the IMF angle and magnetic reconnection rate at Mercury. For the typical solar wind dynamic pressure, our model suggests that the solar wind proton precipitation through the cusps is longitudinally centered near noon with ~11o latitudinal extent in the north and ~21o latitudinal extent in the south, which is consistent with MESSENGER observations. We found an anti-correlation in the incidence area on the surface and the incidence particle rate between the northern and southern cusp precipitation such that the total area and the total rate through both of the cusps remain constant and independent of the IMF orientation. We also show that the solar wind proton incidence rate to the entire surface of Mercury is higher when the IMF has a northward component and nearly half of the incidence flux impacts the low latitudes on the nightside. During extreme solar events (e.g., Coronal Mass Ejections) a large area on the dayside surface of Mercury is exposed to the solar wind plasma, especially in the southern hemisphere. Our model suggests that over 70 nPa solar wind dynamic pressure is required for the entire surface of Mercury to be exposed to the solar wind plasma.
Modelling the in situ solar and thermal radiation environment for future entry probe missions to Venus
Authors: Irwin Patrick , Wilson Colin , Alday Juan , Roos-Serote Maarten , Barstow Jo , Aslam Shahid
Published: October 2020

In this presentation we will describe recent work to model upward and downward fluxes of solar and thermal radiation in the atmosphere of Venus using the NEMESIS radiative transfer and retrieval tool (Irwin et al., JQSRT, 109, 1136, 2008). Using a plane-parallel matrix operator multiple-scattering model we simulate the internal 3D radiation field within Venus’ atmosphere and compare our simulations with the observations of the Pioneer Venus and Venera 13 and 14 entry probes. Such simulations allow us to assess the availability of sunlight and the visibility of the sun azimuth direction in the cloud layer for potential balloon missions, and also enables us to predict at what altitude the surface will become visible for probes descending on dayside. A reanalysis of the Venera 13 and 14 radiance spectra observations will be used to reassess earlier estimates of cloud structure and water vapour abundance. Such modelling also allows us to simulate the visible appearance of Venus’ atmosphere during the descent of a probe mission as will be shown.
Impact of magneto-rotational instability on grain growth in protoplanetary disks
Authors: Gong Munan , Ivlev Alexei , Zhao Bo , Caselli Paola
Published: October 2020

Grain growth in protoplanetary disks is the first step towards planet formation. One of the most important pieces in the grain growth model is calculating the collisional velocity between two grains induced by the turbulent motion of the gas. The collisional velocities in previous works are obtained based on the assumption that the turbulence is hydrodynamic with the Kolmogorov power spectrum. However, realistic protoplanetary disks are magnetized, and turbulent motions can be induced by the magneto-rotational instabilities (MRI).To understand the impact of MRI turbulence on grain growth, we carry out 3D MHD simulations of the MRI as well as driven turbulence, for a range of physical and numerical parameters. Figure 1 illustrates the magnetic field structure in one of the MRI simulations. We investigate two fundamental parameters of the turbulence that can have large impacts on grain collision velocities, the kinetic energy spectrum and the turbulence autocorrelation time. We find that the convergence of the turbulence α-parameter does not necessarily imply the convergence of the energy spectrum. The MRI turbulence is largely solenoidal, for which we observe a persistent kinetic energy spectrum with a -4/3 slope, shallower than the -5/3 slope in the Kolmogorov turbulence (Figure 2). The same is obtained for solenoidal driven turbulence with and without magnetic field, over more than 1 dex near the dissipation scale. This power-law slope appears to be converged in terms of numerical resolution, and to be due to the bottleneck effect. The kinetic energy in the MRI turbulence peaks at the fastest growing mode of the MRI. In contrast, the magnetic energy peaks at the dissipation scale. The magnetic energy spectrum in the MRI turbulence does not show a clear power-law range, and is almost constant over approximately 1 dex near the dissipation scale. The turbulence autocorrelation time is nearly constant at large scales, limited by the shearing timescale, and shows a power-law drop at small scales, with a slope close to -1, steeper than that of the eddy crossing time.The deviation from the standard picture of the Kolmogorov turbulence can have a significant impact on the grain collisional velocities. Figure 3 shows the collisional velocities in Kolmogorov turbulence and turbulence observed in the simulations. For small grains that are well coupled to the gas, the collisional velocities can vary by orders of magnitude across different turbulence models. To understand the dust growth in protoplanetary disks, better computational techniques are needed to achieve the large dynamical range necessary for resolving the turbulence spectrum in the future.Reference:Gong M., Ivlev A. V., Zhao B., Caselli P., 2020, ApJ, 891, 172
Light curves and spin rates of Earth co-orbital asteroids
Authors: Borisov Galin , Christou Apostolos , Bagnulo Stefano , Cellino Alberto , Dell'Oro Aldo
Published: October 2020

The so-called Earth co-orbitals are asteroids that share Earth’s orbit and are potentially linked to leftover material from the formation of the rocky planets. They are difficult to observe from the ground, because of their low conjunction frequency. Here we present light curves of a number of co-orbitals successfully observed during very narrow visibility periods when they approach the Earth. We used the FoReRo2 instrument attached on the 2-m RCC telescope at the Bulgarian National Astronomical Observatory - Rozhen. The figure shows the light curve of (418849) 2008 WM64, which has a semi-major axis a=1.005 AU, an orbital period of 1.01 yr and absolute magnitude H=20.6.Knowing their spin rate and determining the magnitude of the YORP and Yarkovsky effects we can make inferences about their creation (YORP-induced fission of a parent body) and their past orbital evolution. AcknowledgementsWork reported here was supported via grant ST/R000573/1 from the UK Science and Technology Facilities Council (STFC). Astronomical research at the Armagh Observatory and Planetarium is grant-aided by the Northern Ireland Department for Communities (DfC).
Phase curves of >40,000 small solar system bodies obtained by the Tomo-e Gozen transient survey
Authors: Yoshida Fumi , Ito Takashi , Urakawa Seitaro , Terai Tsuyoshi , Tominaga Nozomu , Morokuma Tomoki , Sako Shigeyuki , Ohsawa Ryou , Tanaka Masaomi , Hamasaki Ryo
Published: October 2020

The Tomo-e Gozen project conducts optical wide-field survey programs with a wide-field CMOS camera, Tomo-e Gozen, attached on the 105-cm Schmidt telescope at the Kiso Observatory, the University of Tokyo, Japan. Tomo-e Gozen is the world's first wide-field CMOS camera which covers 20 square degrees with 84 chips of 35 mm full HD CMOS image sensors. A wide-field and high-cadence survey in the optical wavelengths began in 2018 with the Tomo-e Gozen (hereafter referred to as the Tomo-e Gozen transient survey). The main purpose of this survey is to detect young supernovae. However, the survey simultaneously detects a large number of moving objects in their images. As one of the by-products of the survey, here we show our preliminary result about production of phase curves (solar phase angles versus absolute magnitude) of more than 44,000 small solar system bodies including main-belt asteroids, near-Earth asteroids, Jupiter Trojans, Centaurs, and Transneptunian objects (this number is as of April 11, 2020). Combining the moving object catalogue derived from the survey and the output ephemeris that the Horizons/JPL system provides, we are now able to obtain phase curves of these objects almost automatically. As the Kiso moving object catalogue is updated and being expanded on a daily basis, the number of the objects (small bodies) that we deal with goes up as well. Our result, when completed, will make a fair complement as well as a significant keystone to what is already published such as from the Pan-STARRS systematic survey on the knowledge of the surface characteristics of the small solar system bodies.
Physical properties of near-Earth asteroids manually recovered from NEOWISE data
Authors: Masiero Joseph , Mainzer Amy , Cutri Roc , Grav Tommy , Wright Edward
Published: October 2020

The Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) spacecraft was reactivated in December 2013 and since then has been conducting an all-sky survey at 3.4 and 4.6 microns to discover and characterize asteroids and comets that come close to the Earth.  NEOWISE employs an automated pipeline for the detection of moving objects, recording their astrometry and photometry and reporting positions to the Minor Planet Center for archiving.  However, there are a subset of near-Earth objects that are not found by the automated system due to rates of motion or acceleration outside the pipeline limits, an insufficient number of detections, or confusion with background sources.  Because NEOWISE archives every full-frame image obtained during the survey, detections of these objects can be recovered by manually searching the expected positions for coincident sources.We have performed searches for near-Earth objects in the NEOWISE archives from 2013 to 2019, recovering detections for over 400 objects and enabling fitting of their diameters and albedos (Masiero et al. 2018, Masiero et al. 2020).  This builds on earlier work that searched the data from the cryogenic phase of the original WISE mission (Mainzer et al. 2014).  Objects found through this technique tend to be smaller than those detected by the automated processing. The distribution of albedos for these objects is skewed to high reflectivities, as is expected for a population that is optically-selected.Here we present the results of our searches along with the physical properties of the recovered objects.  We also will discuss the reasons these objects were missed by the automated processing, and what the observed physical property distribution implies about any remaining objects still waiting to be found in the data.
Destiny+ Dust Analyzer – Campaign & timeline preparation for interplanetary & interstellar dust observation during the 4-year transfer phase from Earth to Phaethon
Authors: Sommer Maximilian , Krüger Harald , Srama Ralf , Hirai Takayuki , Kobayashi Masanori , Arai Tomoko , Sasaki Sho , Kimura Hiroshi , Moragas-Klostermeyer Georg , Strub Peter , Lohse Ann-Kathrin
Published: October 2020

The Destiny+ mission (Demonstration and Experiment of Space Technology for Interplanetary voyage Phaethon fLyby and dUst Science) has been selected as part of its M-class Space Science Program by the Japanese space agency JAXA/ISAS and is set to launch in 2023/2024. The mission target is the active asteroid (3200) Phaethon with a projected flyby in early 2028. The scientific payload consists of two cameras (the Telescopic Camera for Phaethon, TCAP, and the Multi-band Camera for Phaethon, MCAP), and the Destiny+ Dust Analyzer (DDA). DDA is the technological successor to the Cosmic Dust Analyzer (CDA) aboard Cassini-Huygens, which prominently investigated the dust environment of the Saturnian system. The DDA sensor is designed as a combination of impact ionization time-of-flight mass spectrometer and trajectory sensor, which will allow for the analysis of sub-micron and micron sized dust particles with respect to their composition (mass resolution m/Δm ≈ 100-150), mass, electrical charge, velocity (about 10% accuracy), and impact direction (about 10° accuracy).Besides attempting to sample the impact-generated dust cloud around Phaethon during the flyby, DDA will be actively observing the interplanetary & interstellar dust environment over the roughly four years spanning cruise phase from the Earth-Moon system through interplanetary space. After launch into a GTO-like orbit, Destiny+ will first employ its solar-electric propulsion system to spiral up to the lunar orbit within about 18 months, followed by a series of lunar swingbys and interim coasting phases in distant cislunar space, accumulating momentum to leave the Earth-Moon system at high excess velocity. The subsequent roughly 2-year interplanetary transfer to intercept Phaethon will be characterized by moderate orbital eccentricity of up to 0.1 and largely unpowered coasting phases.During these four years, the DDA sensor will benefit from a maximum pointing coverage range enabled by its dual-axis pointing mechanism and spacecraft attitude flexibility (during times of unpowered flight). This will allow for exhaustive mapping and analysis of the different interplanetary dust populations, as well as interstellar dust encountered in the region between 0.9-1.1 AU.Here, we give a progress report on the science planning efforts for the 4-year transfer phase. We present a tentative observation timeline that assigns scientific campaigns to different phases of the mission, taking into account results of various dust models, as well as operational and technical constraints.
Comparison of the deep atmospheric dynamics of Jupiter and Saturn in light of the Juno and Cassini gravity measurements
Authors: Kaspi Yohai , Galanti Eli , Showman Adam , Stevenson David , Guillot Tristan , Iess Luciano , Bolton Scott
Published: October 2020

The nature and structure of the observed east-west flows on Jupiter and Saturn has been a long-standing mystery in planetary science. This mystery has been recently unraveled by the accurate gravity measurements provided by the Juno mission to Jupiter and the Grand Finale of the Cassini mission to Saturn. These two experiments, which coincidentally happened around the same time, allowed the determination of the overall vertical and meridional profiles of the zonal flows on both planets. In this talk, we discuss what has been learned about the zonal jets on the gas giants in light of the new data from these two experiments. The gravity measurements not only allow the depth of the jets to be constrained, yielding the inference that the jets extend to roughly 3000 and 9000 km below the observed clouds on Jupiter and Saturn, respectively, but also provide insights into the mechanisms controlling these zonal flows. Specifically, for both planets this depth corresponds to the depth where electrical conductivity is within an order of magnitude of 1 S/m, implying that the magnetic field likely plays a key role in damping the zonal flows. An intrinsic characteristic of any gravity inversion, as discussed here, is that the solutions might not be unique. We analyze the robustness of the solutions and present several independent lines of evidence supporting the inference that the jets reach these depths.
Machine learning classification of new asteroid families members
Authors: Carruba Valerio
Published: October 2020

Asteroid families are groups of asteroids that are the product of collisions or of the rotational fission of a parent object.  These groups are mainly identified in proper elements or frequencies domains.   Because of robotic telescope surveys, the number of known asteroids has increased from about 10,000 in the early 90's to more than 750,000 nowadays. Traditional approaches for identifying new members of asteroid families, like the hierarchical clustering method (HCM), may   struggle to keep up with the growing rate of new discoveries. Here we used machine learning classification algorithms to identify new family members based on the orbital distribution in proper (a,e,sin(i)) of previously known family constituents. We compared the outcome of nine classification algorithms from stand alone and ensemble approaches.  The Extremely Randomized Trees (ExtraTree) method had the highest precision, enabling to  retrieve up to 97% of family members identified with standard HCM.
Evidence of Enhanced Ionization During Early Planet Formation
Authors: Schwarz Kamber , Maret Sebastien , Lefevre Charlene , Andre Philippe , Belloche Arnaud , Bergin Edwin , Codella Claudio
Published: October 2020

There is growing observational evidence that giant planet formation happens early, within a million years of the coalescence of the protoplanetary disk. Ionization rate is one of the most important parameters controlling both the chemical and dynamical processes in these disks. What few observational constrains on ionization currently exists suggest overall low ionization, limiting the processes able to take place. This is seemingly in conflict with chemical models which demonstrate the importance of ionization for the chemical processing of volatile carbon and observations which suggest such processing is ubiquitous and happens quickly. I will present new NOEMA observations which, when combined with chemical modeling, are indicative of enhanced ionization rates in the envelopes of three Class I protostars.  I will then discuss the potential impact of this early enhancement on the chemical composition of the material available to forming planets.
A Deep Learning Pipeline for Unified Modelling of Time-Correlated Noise in Exoplanets Observations
Authors: Morvan Mario , Nikolau Nikos , Tsiaras Angelos , Waldmann Ingo
Published: October 2020

The precise derivation of transit depths from stellar light curves is a key component in the construction of exoplanet transit spectra, and thereby for the characterization of exoplanet atmospheres. However, it is still deeply affected by various kinds of complex systematic errors and noises taking their source from host stars’ or instruments’ variability. On the other hand, as the volume of exoplanetary data is quickly increasing, a new way is being opened up for using machine learning as part of the data processing pipeline. By training a recurrent neural network to model the temporal dependencies in stellar light curves, our results on both real on simulated light curves highlight that it is possible to:Model accurately the compound of trends and periodic effects with few or no assumptions about the instrument, star, or planetary signals
Improve the understanding of each instrument’s systematic behaviour
Optimise a deep detrending model jointly with a transit fit
Leverage the cross-light curves and cross-instruments information
Such an approach therefore paves the way for a global, flexible and efficient noise-correction pipeline which will be of paramount importance to make the most of exoplanets observations and provide high precision spectra to subsequent atmospheric retrieval pipelines.
Chondrule Formation by the Jovian Sweeping Secular Resonance
Authors: Gong Munan , Zheng Xiaochen , Lin Douglas , Silsbee Kedron , Baruteau Clement , Mao Shude
Published: October 2020

Chondritic meteorites, or chondrites, contain some of the oldest and most primitive solids in our solar system. They record the physical conditions at the early phase of the solar nebula evolution and planet formation. Chondrites are mainly composed of chondrules, which are millimeter-sized silicate spheroids. To form the chondrules we see today, chondrule precursors need to be heated to temperatures above 1600 K and cooled down rapidly on timescales of minutes to hours. Considering ordinary chondrites make up about 10% of meteorites found on Earth, chondrule heating events should be common in the early solar system.  
One of the most promising mechanisms for chondrule heating is the passage through bow shocks of highly eccentric planetesimals in the protoplanetary disk. This mechanism explains many features in the thermal histories of chondrules, such as the ambient temperature, the peak temperature, and the cooling rate. However, theoretical models so far have difficulties producing a large number of planetesimals with high eccentricities, which is needed to form chondrules efficiently.
In this paper, we investigate a scenario in which the orbits of planetesimals are influenced by both Jupiter and a depleting protoplanetary disk. As the disk mass decreases with time, the location of the Jovian secular resonance moves from the outer to the inner disk. This phenomenon is called the sweeping secular resonance. We propose that this mechanism, illustrated in Figure 1, can explain chondrule formation, by exciting the planetesimals in the asteroid belt region to high eccentricity orbits. We study the orbital evolution of planetesimals in the disk using semi-analytic models and numerical simulations. We investigate the dependence of eccentricity excitation on the planetesimal's size as well as the physical environment, and calculate the probability for chondrule formation.
We find that 50-2000 km planetesimals can obtain eccentricities larger than 0.6, as shown in Figure 2, and lead to effective chondrule heating. Most chondrules form in high-velocity shocks, in low-density gas, and in the inner disk. Figure 3 shows that the age spread of chondrule is comparable to the depletion timescale of the disk, which is directly linked to the timescale for the secular resonance to pass through the asteroid belt region. The fraction of chondrule precursors that become chondrules is about 4-9% between 1.5-3 AU, consistent with observational constraints.  
Our model suggests that the depletion timescale for the protoplanetary disk around the Sun is comparable to the age spread of chondrules at around 1 Myr; and that Jupiter formed before chondrules, no more than 0.7 Myr after the formation of the CAIs.
Reference:
Gong M., Zheng X., Lin D.~N.~C., Silsbee K., Baruteau C., Mao S., 2019, ApJ, 883, 164
 
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The PLATO mission: Studying the diversity of exoplanets orbiting up to the habitable zone of Sun-like stars
Authors: Heras Ana Maria , Rauer Heike , Aerts Conny , Deleuil Magali , Gizon Laurent , Goupil Marie-Jo , Mas-Hesse Miguel , Piotto Giampaolo , Pollacco Don , Ragazzoni Roberto , Ramsay Gavin , Udry Stéphane
Published: October 2020

The ESA PLATO mission will provide unprecedented data to study the diversity of planets orbiting up to the habitable zone of bright Sun-like stars. PLATO will detect and characterise exoplanets using the transit method combined with ground-based radial velocity measurements, and study the host stars with asteroseismology. PLATO’s core observing sample consists of Sun-like stars of V < 11. For statistical studies, PLATO will also monitor a large sample of Sun-like stars with V < 13 and cool late-type dwarfs with V < 16. To benefit from PLATO’s advanced photometric capabilities, the general community will be invited to submit proposals on complementary science topics in the framework of a guest observer’s programme. The PLATO payload consists of four groups of six cameras each that overlap covering a total field of about 2150 deg2 with four different sensitivities. Two additional cameras will observe the brightest stars (V < 8.5) in two-colours, and will be used as fine guidance sensor. PLATO is the third medium-class mission in ESA’s Cosmic Vision programme, with a planned launch date in 2026. The satellite will operate in an orbit around the second Lagrange point, L2. We will present the status of the mission science definition and performance, and of the satellite and ground-segment developments. 
In-situ detection of cometary cyanogen (NCCN)
Authors: Hänni Nora , Altwegg Kathrin , Pestoni Boris , Rubin Martin , Schroeder Isaac , Schuhmann Markus , Wampfler Susanne
Published: October 2020

For a long time it was thought that the cyano (CN) radical, observed remotely many times in various stellar and interstellar environments, is exclusively a photodissociation product of hydrogen cyanide (HCN). Bockelée-Morvan et al. (1984) first questioned this notion based on remote observations of comet IRAS-Araki-Alcock. They reported an upper limit for the HCN production rate which was smaller than the CN production rate previously derived by A’Hearn et al. (1983). Even today, this discrepancy observed for some comets is not resolved although many alternative parents have been suggested. Among the volatile candidates, cyanogen (NCCN), cyanoacetylene (HC3N) and acetonitrile (CH3CN), according to Fray et al. (2005), are the most promising ones. While cyanoacetylene and acetonitrile are known to be present in trace amounts in comets, as reported for comet Hale-Bopp by Bockelée-Morvan et al. (2000) and for comet 67P/Churyumov-Gerasimenko by Le Roy et al. (2015) and Rubin et al. (2019), the abundance of cyanogen in comets is unknown. Altwegg et al. (2019) were the first to mention its detection in the inner coma of comet 67P/Churyumov-Gerasimenko, target of ESA’s Rosetta mission.In this work, we track the signatures of cyanogen in the ROSINA/DFMS (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/ Double Focusing Mass Spectrometer; Balsiger et al. (2007)) data, collected during the Rosetta mission phase. We derive abundances relative to water for three distinct periods, indicating that cyanogen is not abundant enough to explain the CN production in comet 67P together with HCN. Our findings are consistent with the non-detection of cyanogen in the interstellar medium. A’Hearn M.F., Millis R.L., 1983, IAU Circ., 3802Altwegg K., Balsiger H., Fuselier S.A., 2019, Annu. Rev. Astron. Astrophys., 57, 113–55Balsiger H. et al., 2007, Space Science Reviews, 128, 745-801Bockelée-Morvan D., Crovisier J., Baudry A., Despois D., Perault M., Irvine W.M., Schloerb F.P., Swade D., 1984, Astron. Astrophys., 141, 411-418Bockelée-Morvan et al., 2000, Astron. Astrophys., 353, 1101–1114.Fray N., Bénilan Y., Cottin H., Gazeau M.-C., Crovisier J., 2005, Planetary and Space Science, 53, 1243-1262Le Roy L. et al., 2015, Astron. Astrophys., 583, A1Rubin M. et al., 2019, MNRAS, 489, 594-607
Atmospheric Characterization via Broadband Color Filters on the PLAnetary Transits and Oscillations of stars (PLATO) Mission
Authors: Grenfell John Lee , Godolt Mareike , Cabrera Juan , Carone Ludmila , Garcia Munoz Antonio , Kitzmann Daniel , Smith Alexis M. S. , Rauer Heike
Published: October 2020

We assess broadband color filters for the two fast cameras on the PLAnetary Transits and Oscillations (PLATO) of stars space mission with respect to exoplanetary atmospheric characterization. We focus on Ultra Hot Jupiters and Hot Jupiters placed 25pc and 100pc away from the Earth and warm Super-Earths placed 10pc and 25pc away. Our analysis takes as input literature values for the difference in transit depth between the broadband lower (500-675nm) wavelength interval (hereafter referred to as ”blue“) and the upper (675-1125nm) broadband wavelength interval (hereafter referred to as ”red“) for transmission, occultation and phase curve analyses. Planets orbiting main sequence central stars with stellar classes F, G, K and M are investigated. We calculate the signal-to-noise ratio with respect to photon and instrument noise for detecting the difference in transit depth between the two spectral intervals. Results suggest that bulk atmospheric composition and planetary geometric albedos could be detected for (Ultra) Hot Jupiters up to ~100pc (~25pc) with strong (moderate) Rayleigh extinction. Phase curve information could be extracted for Ultra Hot Jupiters orbiting K and G dwarf stars up to 25pc away. For warm Super-Earths, basic atmospheric types (primary and water-dominated) and the presence of sub-micron hazes in the upper atmosphere could be distinguished for up to a handful of cases up to ~10pc (manuscript accepted in Experimental Astronomy).
Superthermal electron deposition on the Mars nightside during ICMEs
Authors: Xu Shaosui , Curry Shannon , Mitchell David , Luhmann Janet , Lillis Robert , Dong Chuanfei
Published: October 2020

Superthermal electron precipitation is one of the main sources supporting the Mars nightside ionosphere. It is expected that solar wind electron fluxes are to increase significantly during interplanetary coronal mass ejections (ICME) and therefore an enhanced nightside ionospheric density. This study is to quantify the variation of the precipitating and deposited electron fluxes during five of the most extreme ICMEs encountered by Mars Global Surveyor (MGS). We find energy fluxes correlate better with the upstream dynamic pressure proxy than number fluxes and electron fluxes increase more at high energies, which means electrons tend to have a lower peak production altitude during storm times. The precipitating and net/deposited fluxes are increased up to an order of magnitude from low to high dynamic pressures. The estimated total electron content (TEC) is a few times of 1014 m-2 for quiet times and on the order of 1015 m-2 for storm times, with an enhancement up to an order of magnitude locally near strong crustal fields. Crustal magnetic fields have an effect on the deposited fluxes with more prominent magnetic reflection over strong magnetic fields during quiet periods, which is significantly reduced during storm times. Lastly, we estimate a global energy input from downward fluxes of 1.3×108 W and 5.5×108 W and the globally deposited energy from net fluxes of 2.3×107 W and 1.6×108 W for quiet and storm time periods, a factor of 4 and 7 enhancement globally, respectively, but up to an order of magnitude locally near strong crustal fields.
The escape of CO2+ and other heavy minor ions from Mars
Authors: Maes Lukas , Fraenz Markus , McFadden James , Benna Mehdi
Published: October 2020

Next to its main constituent O2+, the Martian ionosphere consists of several other ion species, like CO2+, O+, CO+, HCO+, N2+, etc. The ionospheric escape is dominated by O2+ and O+ ions, and as a result the escape of these species is well studied. The other, minor ion species are more difficult to measure in the escaping plasma, because their contribution is typically obscured in the mass spectra of ion instruments by the more abundant O2+ peak.In this study we use data from the SupraThermal And Thermal Ion Composition instrument (STATIC) on board MAVEN to investigate the escape of these ions. We use a peak-fitting method to separate the contribution of several ion species, including O2+, CO2+, O+ and ions with a mass between 28-30 AMU. Our method is validated against Neutral Gas and Ion Mass Spectrometer (NGIMS), also onboard MAVEN, and results in the ionosphere agree qualitatively very well.We apply this method to STATIC data from January 2016 until May 2019 to perform a statistical study examining the escape of low energy (=16 AMU) ions throughout the Martian magnetosphere and its surrounding. We find that CO2+ ions do escape through the tail but at a very limited rate, namely at less than 1% of the O2+ escape rate. Ions with a mass between 28-30 AMU, however, are found to constitute a significant part of the ionospheric outflow, with an escape rate 30% of the O2+ rate and 15% of the total heavy ion escape.
Titan’s Ultraviolet Airglow Variability with Solar Cycle and Saturn Local Time
Authors: Royer Emilie , Cooper Marielle , Ajello Joseph , Esposito Larry , Crary Frank
Published: October 2020

The Cassini spacecraft observed Titan’s upper atmosphere and its airglow emissions from 2005 to 2017. It is now established that the solar XUV radiation is the main source of dayglow, while magnetospheric particle precipitation principally acts on the nightside of the satellite. Nevertheless, one of the questions remaining unanswered after the end of the Cassini mission concerns the role and quantification of the magnetospheric particle precipitation and other minor sources such as micrometeorite precipitation and cosmic galactic ray at Titan. We report here on enhancements observed in Ultraviolet (UV) observations of Titan airglow made with the Cassini-Ultraviolet Imaging Spectrograph (UVIS). Enhancements are correlated with magnetospheric changing conditions occurring while the spacecraft, and thus Titan, are known to have crossed Saturn’s magnetopause and have been exposed to the magnetosheath environment. The processing and interpretation of 13+ years of airglow observations at Titan allows now for global studies of the upper atmosphere as a function of the Saturn Local Time (SLT) and the solar cycle.Nitrogen airglow occur at about 1100 km of altitude in Titan’s upper atmosphere. Observations by the Cassini-UVIS instrument revealed the emission of the LBH band system, VK band system as well as Nitrogen atomic emission lines at 1085Å and 1493Å, as the prominent features of airglow emissions at Titan, as shown in Figures 1 and 2. Measurements were made at a wide range of solar incidence angles and Saturn Local Time (SLT), during the entire Cassini mission, allowing for the investigation of the upper atmosphere response to the magnetospheric environment and energetic particle precipitation. Additionally, observations were taken in a variety of solar condition, from solar maximum to minimum. UVIS observations of Titan around 12PM SLT (near Saturn’s magnetopause) present evidence of Titan’s upper atmosphere response to a fluctuating magnetospheric environment.Figure 1. Airglow intensity as a function of the saturn Local Time (SLT), for observation taken close the Saturn’s magnetopause (12PM SLT, labelled ‘12h’) and observations taken around miadnight SLT (labelled ‘24h’). Dayglow spectra exhibit higher averaged airglow intensity than Nightglow spectra.We present here comparisons of the spectral emissions from the dayglow (Solar incidence angle