Search

Context. Saturn has an excess of irregular moons. This is thought to be the result of past collisional events. Debris produced during such episodes in the neighborhood of a host planet can evolve into co-orbitals trapped in quasi-satellite and/or horseshoe resonant states. A recently announced centaur, 2013 VZ70, follows an orbit that could be compatible with those of prograde Saturn's co-orbitals. Aims. We perform an exploration of the short-term dynamical evolution of 2013 VZ70 to confirm or reject a co-orbital relationship with Saturn. A possible connection with Saturn's irregular moon population is also investigated. Methods. We studied the evolution of 2013 VZ70 backward and forward in time using N-body simulations, factoring uncertainties into the calculations. We computed the distribution of mutual nodal distances between this centaur and a sample of moons. Results. We confirm that 2013 VZ70 is currently trapped in a horseshoe resonant state with respect to Saturn but that it is a transient co-orbital. We also find that 2013 VZ70 may become a quasi-satellite of Saturn in the future and that it may experience brief periods of capture as a temporary irregular moon. This centaur might also pass relatively close to known irregular moons of Saturn. Conclusions. Although an origin in trans-Neptunian space is possible, the hostile resonant environment characteristic of Saturn's neighborhood favors a scenario of in situ formation via impact, fragmentation, or tidal disruption as 2013 VZ70 can experience encounters with Saturn at very low relative velocity. An analysis of its orbit within the context of those of the moons of Saturn suggests that 2013 VZ70 could be related to the Inuit group. Also, the mutual nodal distances of 2013 VZ70 and the moons Fornjot and Thrymr are below the first percentile of the distribution., 10 pages, 8 figures, 5 tables, 1 appendix. Accepted for publication in Astronomy and Astrophysics. Abstract abridged. After language edition

BACKGROUND & AIMS The development of accurate non-invasive tests to detect and measure the extent of fibrosis and disease activity in patients with non-alcoholic steatohepatitis (NASH) - the progressive phenotype of non-alcoholic fatty liver disease (NAFLD) - is of great clinical importance. Herein, we aimed to validate the performance of PRO-C3 and ADAPT for the detection of moderate/severe fibrosis within the CENTAUR screening population. METHODS PRO-C3 was assessed in plasma from the screening population of the phase IIb CENTAUR study (NCT02217475) in adults with NASH and liver fibrosis. The relation between PRO-C3 and histologic features of NASH was evaluated, as well as the demographics of patients with high and low levels of PRO-C3. The diagnostic ability of PRO-C3, as a standalone marker or incorporated into ADAPT, to identify patients with F≥2 and NASH was estimated using receiver-operating characteristic analysis and logistic regression models. RESULTS A total of 517 individuals with matched biopsy and PRO-C3 measurements were included. Patients with PRO-C3 levels ≥20.2 ng/ml showed increased levels of insulin, HOMA-IR, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, and platelet count compared to patients with low PRO-C3 (p

Two extremely red main-belt asteroids: 203 Pompeja and 269 Justitia, were identified from combined visible and near-infrared spectroscopic observations collected at the IRTF and SAO observatories. These two asteroids have a redder spectral slope than any other D-type body, which are the reddest objects in the asteroid belt, and similar to RR and IR-class objects found in the outer Solar System among trans-Neptunian objects and Centaurs. Spectroscopic results suggest the presence of complex organic materials on the surface layer of these asteroids, implying that they could have formed in the vicinity of Neptune and been transplanted to the main belt region during a phase of planetary migration. 203 Pompeia is the only very red asteroid known so far among the ~250 bodies with diameter larger than 110 km (i.e. presumably structurally intact) found in the asteroid belt. These discoveries add another piece of evidence that the main asteroid belt hosts a population of bodies that were formed in the outskirt of the Solar System., 12 pages, 5 figures, 1 tables, Accepted for publication in ApJ Letters

Katarzyna Marciniak's introductory words explain to the readers the place of the volume "Our Mythical Education: The Reception of Classical Myth Worldwide in Formal Education, 1900–2020", edited by Lisa Maurice, in the context of the "Our Mythical Childhood" project and the book series. The "Foreword" is available also at the Publisher's website, University of Warsaw Press: https://www.wuw.pl/data/links/d3e06046f996d7f6be394a8b02fd2380/14689_8804.pdf Open Access of the complete volume at https://www.wuw.pl/product-eng-14887-Our-Mythical-Education-The-Reception-of-Classical-Myth-Worldwide-in-Formal-Education-1900-2020-PDF.html, This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme under grant agreement No 681202 (2016–2022), "Our Mythical Childhood... The Reception of Classical Antiquity in Children's and Young Adults' Culture in Response to Regional and Global Challenges", ERC Consolidator Grant led by Katarzyna Marciniak. Project's Website: www.omc.obta.al.uw.edu.pl licensed under CC BY 3.0 PL, https://creativecommons.org/licenses/by/3.0/pl/legalcode

Interplanetary dust grains originate from a variety of source bodies, including comets, asteroids, and Edgeworth–Kuiper belt objects. Centaurs, generally defined as those objects with orbits that cross the outer planets, have occasionally been observed to exhibit cometary-like outgassing at distances beyond Jupiter, implying that they may be an important source of dust grains in the outer Solar system. Here, we use an interplanetary dust grain dynamics model to study the behaviour and equilibrium distribution of Centaur-emitted interplanetary dust grains. We focus on the five Centaurs with the highest current mass-loss rates: 29P/Schwassmann-Wachmann 1, 166P/2001 T4, 174P/Echeclus, C/2001 M10, and P/2004 A1, which together comprise 98 per cent of the current mass loss from all Centaurs. Our simulations show that Centaur-emitted dust grains with radii s 2 μm have median lifetimes much shorter than their P–R drag lifetimes, suggesting that dynamical interactions with the outer planets are effective in scattering larger grains, in analogy to the relatively short lifetimes of Centaurs themselves. Equilibrium density distributions of grains emitted from specific Centaurs show a variety of structure including local maxima in the outer Solar system and azimuthal asymmetries, depending on the orbital elements of the parent Centaur. Finally, we compare the total Centaur interplanetary dust density to dust produced from Edgeworth–Kuiper belt objects, Jupiter-family comets, and Oort cloud comets, and conclude that Centaur-emitted dust may be an important component between 5 and 15 au, contributing approximately 25 per cent of the local interplanetary dust density at Saturn.

Up to now, 17 Neptune Trojan asteroids have been detected with their orbits being well determined by continuous observations. This paper analyzes systematically their orbital dynamics. Our results show that except for two temporary members with relatively short lifespans on Trojan orbits, the vast majority of Neptune Trojans located within their orbital uncertainties may survive in the solar system age. The escaping probability of Neptune Trojans, through slow diffusion in the orbital element space in 4.5 billion years, is estimated to be ∼50%. The asteroid 2012 UW177 classified as a Centaur asteroid by the IAU Minor Planet Center currently is in fact a Neptune Trojan. Numerical simulations indicate that it is librating on the tadpole-shaped orbit around the Neptune's L4 point. It was captured into the current orbit approximately 0.23 million years ago, and will stay there for at least another 1.3 million years in the future. Its high inclination of i ≈ 54∘ not only makes it the most inclined Neptune Trojan, but also makes it exhibit the complicated and interesting co-orbital transitions between the leading and trailing Trojans via the quasi-satellite orbit phase.

Centaurs, minor planets with a semi-major axis between the orbits of Jupiter and Neptune (5–30 AU), are thought to be among the most diverse small bodies in the solar system. These important targets for future missions may have recently been Kuiper Belt Objects (KBOs), which are thought to be chemically and physically primitive remnants of the early solar system. While the Kuiper Belt spans distances of 30–50 AU, making direct observations difficult, Centaurs' proximity to the Earth and Sun make them more accessible targets for robotic missions. Thus, we outline a mission concept designed to reconnoiter 10199 Chariklo, the largest Centaur and smallest ringed body yet discovered. Named for a legendary Centaur tamer, the conceptual Camilla mission is designed to fit under the cost cap of the National Aeronautics and Space Administration (NASA) New Frontiers program, leveraging a conservative payload to support a foundational scientific investigation to these primitive bodies. Specifically, the single flyby encounter utilizes a combined high-resolution camera/VIS-IR mapping spectrometer, a sub-mm point spectrometer, and a UV mapping spectrometer. In addition, the mission concept utilizes a kinetic impactor, which would provide the first opportunity to sample the composition of potentially primitive subsurface material beyond Saturn, thus providing key insights into solar system origins. Such a flyby of the Chariklo system would provide a linchpin in the understanding of small body composition, evolution, and transport of materials in the solar system.

This final chapter will argue that to tackle the problems of poverty, social inequality and the damage that the penal state has done to individuals and communities, there is a need for a recasting of the notion of citizenship. This chapter is influenced by the work of Somers on notions of citizenship. In her discussion of the abandonment of poor African-Americans in the aftermath of Hurricane Katrina, she argued that this demonstrates that they had been denied the full rights of social inclusion in the political community. It is only by establishing that all individuals should be recognised as citizens of equal moral worth that we can restore meaningful membership in the political community.

Chapter 4 examines Valentin Silvestrov’s journey from avant-garde enfant terrible to neoromantic. It looks at Silvestrov’s goal of musical “unity” or “oneness” in the late 1960s and early 1970s as it developed as a specific inflection of polystylism, influenced by the theories of both Boris Asafyev and Yakov Druskin. This chapter also begins to distinguish Silvestrov’s polystylism from Schnittke’s. It concludes by positioning Silvestrov’s and Schnittke’s first polystylistic works against the reception of polystylism and collage by Soviet critics, composers, and audiences in the 1970s. Among the most potent examples came from an older composer: Dmitriy Shostakovich’s Symphony no. 15, which critics used as a testing ground for the viability of polystylism in the Soviet Union.

Context. Centaurs go around the Sun between the orbits of Jupiter and Neptune. Only a fraction of the known centaurs have been found to display comet-like features. Comet 29P/Schwassmann-Wachmann 1 is the most remarkable active centaur. It orbits the Sun just beyond Jupiter in a nearly circular path. Only a handful of known objects follow similar trajectories. Aims. We present photometric observations of 2020 MK4, a recently found centaur with an orbit not too different from that of 29P, and we perform a preliminary exploration of its dynamical evolution. Methods. We analyzed broadband Cousins R and Sloan g', r', and i' images of 2020 MK4 acquired with the Jacobus Kapteyn Telescope and the IAC80 telescope to search for cometary-like activity, and to derive its surface colors and size. Its orbital evolution was studied using direct N-body simulations. Results. Centaur 2020 MK4 is neutral-gray in color and has a faint, compact cometary-like coma. The values of its color indexes, (g'-r')=0.42+/-0.04 and (r'-i')=0.17+/-0.04, are similar to the solar ones. A lower limit for the absolute magnitude of the nucleus is Hg=11.30+/-0.03 mag which, for an albedo in the range of 0.1-0.04, gives an upper limit for its size in the interval (23, 37) km. Its orbital evolution is very chaotic and 2020 MK4 may be ejected from the Solar System during the next 200 kyr. Comet 29P experienced relatively close flybys with 2020 MK4 in the past, sometimes when they were temporary Jovian satellites. Conclusions. We confirm the presence of a coma of material around a central nucleus. Its surface colors place this centaur among the most extreme members of the gray group. Although its past, present, and future dynamical evolution resembles that of 29P, more data are required to confirm or reject a possible connection between the two objects and perhaps others., Comment: 15 pages, 15 figures, 6 tables, 3 appendixes. Accepted for publication in Astronomy and Astrophysics. Abstract abridged. After A&A language editing

Few shot learning with large language models has the potential to give individuals without formal machine learning training the access to a wide range of text to text models. We consider how this applies to creative writers and present Story Centaur, a user interface for prototyping few shot models and a set of recombinable web components that deploy them. Story Centaur’s goal is to expose creative writers to few shot learning with a simple but powerful interface that lets them compose their own co-creation tools that further their own unique artistic directions. We build out several examples of such tools, and in the process probe the boundaries and issues surrounding generation with large language models.

Full list of authors: Santos-Sanz, P.; Ortiz, J. L.; Sicardy, B.; Benedetti-Rossi, G.; Morales, N.; Fernández-Valenzuela, E.; Duffard, R.; Iglesias-Marzoa, R.; Lamadrid, J. L.; Maícas, N.; Pérez, L.; Gazeas, K.; Guirado, J. C.; Peris, V.; Ballesteros, F. J.; Organero, F.; Ana-Hernández, L.; Fonseca, F.; Alvarez-Candal, A.; Jiménez-Teja, Y. Vara-Lubiano, M.; Braga-Ribas, F.; Camargo, J. I. B.; Desmars, J.; Assafin, M.; Vieira-Martins, R.; Alikakos, J.; Boutet, M.; Bretton, M.; Carbognani, A.; Charmandaris, V.; Ciabattari, F.; Delincak, P.; Fuambuena Leiva, A.; González, H.; Haymes, T.; Hellmich, S.; Horbowicz, J.; Jennings, M.; Kattentidt, B.; Kiss, Cs; Komžík, R.; Lecacheux, J.; Marciniak, A.; Moindrot, S.; Mottola, S.; Pal, A.; Paschalis, N.; Pastor, S.; Perello, C.; Pribulla, T.; Ratinaud, C.; Reyes, J. A.; Sanchez, J.; Schnabel, C.; Selva, A.; Signoret, F.; Sonbas, E.; Alí-Lagoa, V.--This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited., We predicted a stellar occultation of the bright star Gaia DR1 4332852996360346368 (UCAC4 385-75921) (mV = 14.0 mag) by the centaur 2002 GZ32 for 2017 May 20. Our latest shadow path prediction was favourable to a large region in Europe. Observations were arranged in a broad region inside the nominal shadow path. Series of images were obtained with 29 telescopes throughout Europe and from six of them (five in Spain and one in Greece) we detected the occultation. This is the fourth centaur, besides Chariklo, Chiron, and Bienor, for which a multichord stellar occultation is reported. By means of an elliptical fit to the occultation chords, we obtained the limb of 2002 GZ32 during the occultation, resulting in an ellipse with axes of 305 ± 17 km × 146 ± 8 km. From this limb, thanks to a rotational light curve obtained shortly after the occultation, we derived the geometric albedo of 2002 GZ32 (pV = 0.043 ± 0.007) and a 3D ellipsoidal shape with axes 366 km × 306 km × 120 km. This shape is not fully consistent with a homogeneous body in hydrostatic equilibrium for the known rotation period of 2002 GZ32. The size (albedo) obtained from the occultation is respectively smaller (greater) than that derived from the radiometric technique but compatible within error bars. No rings or debris around 2002 GZ32 were detected from the occultation, but narrow and thin rings cannot be discarded. © 2020 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society., P.S-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 'LEO-SBNAF' (MCIU/AEI/FEDER, UE). PS-S, JLO, NM, and RD acknowledge financial support from the State Agency for Research of the Spanish MCIU through the 'Center of Excellence Severo Ochoa' award for the Instituto de Astrofisica de Andalucia (SEV-2017-0709), they also acknowledge the financial support by the Spanish grant AYA-2017-84637-R and the Proyecto de Excelencia de la Junta de Andalucia J.A. 2012-FQM1776. We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI). The research leading to these results has received funding from the European Union's Horizon 2020 Research and Innovation Programme, under Grant Agreement no. 687378, as part of the project `Small Bodies Near and Far' (SBNAF). Part of the research leading to these results has received funding from the European Research Council under the European Community's H2020 (2014-2020/ERC Grant Agreement no. 669416 `LUCKY STAR'). E.F-V. acknowledges funding through the Preeminant Postdoctoral Program of the University of Central Florida. Part of the data were collected during the photometric monitoring observations with the robotic and remotely controlled observatory at the University of Athens Observatory -UOAO (Gazeas 2016). F.J.B. acknowledges financial support by the Spanish grant AYA2016-81065-C2-2-P. A.A-C. acknowledges support from FAPERJ (grant E26/203.186/2016) and CNPq (grants 304971/20162 and 401669/2016-5). A.C. acknowledges the use of the main telescope of theAstronomical Observatory of the Autonomous Region of the Aosta Valley (OAVdA). C.K. has been supported by the grants K125015 and GINOP-2.3.2-15-2016-00003 of the National Research, Development and Innovation Office, Hungary (NKFIH). T.P. and R.K. acknowledge support from the project ITMS No. 26220120029, based on the Research and development program financed from the European Regional Development Fund and from the Slovak Research and Development Agency -the contract No. APVV-150458. We are grateful to the CAHA and OSN staffs. This research is partially based on observations collected at Centro Astronomico Hispano-Aleman (CAHA) at Calar Alto, operated jointly by Junta de Andalucia and Consejo Superior de Investigaciones Cientificas (IAA-CSIC). This research was also partially based on observation carried out at the Observatorio de Sierra Nevada (OSN) operated by Instituto de Astrofisica de Andalucia (CSIC). This article is also based on observations made with the Liverpool Telescope operated on the island of La Palma by the Instituto de Astrofisica de Canarias in the Spanish Roque de losMuchachos Observatory. Partially based on observations made with the Tx40 telescope at the Observatorio Astrofisico de Javalambre in Teruel, a Spanish Infraestructura Cientifico-Tecnica Singular (ICTS) owned, managed and operated by the Centro de Estudios de Fisica del Cosmos de Arag on (CEFCA). Tx40 is funded with the Fondos de Inversiones de Teruel (FITE). This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium).Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.

Somebody walking down the street does not spend much time worrying about comets smashing into Earth or wondering what a so-called centaur might be. This by the way is not a hybrid man-horse in the world of astronomy, but actually a comet that has been captured by the gravitational field of one of the giant planets. Thus, it has become an icy object in an unstable orbit. If it should somehow break loose from its captor’s gravitation field, it could become a potentially hazardous object that could threaten Earth.

One of the major problems encountered in the analysis of medieval texts mentioning animals is that we sometimes just do not know what “modern” animal they actually refer to. The observation applies not only to imaginary creatures, fantastic beasts such as the siren, the centaur, or the dragon, but to numerous animals that are perfectly identifiable today. Medieval authors can use the name we are familiar with to refer to a different animal or describe an animal in a way that is at odds with present-day concepts, so that we sometimes wonder which beast they had in mind. This chapter will try to present a survey of the problems medievalists face when trying to reconstruct what kind of animal is actually being mentioned in medieval texts.

The world is in the throes of a global health, economic, and mental health crisis with severe physical, societal, and economic ramifications. Modern mental health problems are characterized by their complexity, multisystemic nature, and broad societal impact, making them poorly suited to siloed approaches of thinking and innovation. To solve the unprecedented complexities and challenges associated with the current global crisis, a paradigm shift is needed. Convergence science integrates knowledge, tools, and thought strategies from various fields and is the focal point where novel insights arise. In the context of mental health, convergence involves integration of scientists, clinicians, bioinformaticists, global health experts, engineers, technology entrepreneurs, medical educators, caregivers, and patients; synergy between government, academia, and industry is also vital. A convergence mental health approach will lead to improved outcomes for patients and healthcare systems. Predicate examples of convergence science in adjacent fields to mental health provide a model for the path forward. Further, within the field of mental health, there are examples of convergence science currently in action that include early-stage companies, neuroscience initiatives, public health projects, and unconventional funding mechanisms. The world has a historic opportunity to leverage convergence science to lead to a new era of innovation and progress in global mental health. Contributions for this book come from authors affiliated with the Milken Institute, Asia Pacific Economic Cooperation, Organization for Economic Co-operation and Development, the National Academies of Science, Medicine and Engineering, Stanford University, and Harvard University. This book is written for practitioners and leaders in mental health innovation, including clinicians, researchers, policymakers, investors, entrepreneurs, and philanthropists.

Astrometric and photometric observations of the comet 29P/Schwassmann-Wachmann 1 were performed at the Zeiss-1000 telescope of the International Astronomical Observatory Sanglokh (IAOS) of the Institute of Astrophysics, Academy of Sciences of the Republic of Tajikistan in July and August 2017. Although the comet has a short period of revolution it is regarded to be an object of the Centaurs group. Comet was exhibited a new activity this period which we used for analysis of its features. The coordinates of comet were determined and the orbit was calculated, the apparent and absolute magnitudes in BVRI bands were determined, as well the comet color indices and the estimation of nucleus diameter were obtained., 7 pages, 5 figures

This article examines, in its first part, the symbolic aspects of the relation between horses and men, and the mythical figure of the centaur, most often assimilated to virility and male sexual drive, but also to women and their sexuality. In its second and central part, it focuses on Bartabas and Ko Murobushi’s performance, The Centaur and the Animal (2012) while raising ethical issues relating to performing animals. The essay analyzes how this play deconstructs the opposition between masculinity and femininity, as well as between animal and human, among other oppositional pairs such as reason vs. instinct, activity vs. passivity, verticality vs. horizontality or “inclination,” immunity vs. vulnerability, life vs. death, animate vs. inanimate, among others. It posits that Bartabas’s performance opens the possibility of a posthuman and postanimal perspective on the relation between human and nonhuman animals.

Trojans, Centaurs and Trans-Neptunian objects are small dark objects orbiting in the outer Solar System. These objects, still very poorly known, can be considered as fossils of our Solar System, and, as such, they can still contain information about some primordial processes which governed the evolution of the early Solar System. In the next decade, GAIA with its large sky surveys, can allow the discovery of many new objects belonging to these outer solar system populations. In addition, it will provide very precise orbits and visible broad-band colours for many of them.

We examine the dynamics of small bodies in orbits similar to that of comet 29P/Schwassmann-Wachmann 1, i.e. near-circular orbits between Jupiter and Saturn. As of late 2019, there are 14 other known bodies in this region that lie in similar orbits. Previous research has shown that this region of the solar system, which in this work we call the "near Centaur region" (NCR), is not stable, suggesting that any bodies found in it would have very short lifetimes. We performed 20 Myr high-precision numerical simulations of the evolution of massless particles, initially located in the Kuiper belt but close to Neptune, with perihelia slightly below 33 au ("Neptune crossers"). Some of these particles quickly migrate inward, passing through the NCR before becoming Jupiter Family Comets. We find that objects in the NCR do indeed generally travel through it very quickly. However, our simulations reveal that resonant behavior in this region is somewhat common and can trap objects for up to 100 Kyr. We summarize the dynamics of 29P and other observed bodies in the region---two of which seem to be clearly exhibiting resonant behavior---and use our simulations to put limits on the reservoir size of the Neptune crossers, which at its time determines the reservoir size of the Kuiper belt. Finally, we put some constraints on the current population of Centaurs and particularly of the NCR population, based on the injection rates required to keep the observed population of Jupiter family comets in steady-state., 15 pages, 11 figures

This chapter discusses reception of ancient Greek centaurs in Russian tales and apocrypha. From the end of the 13th century, a number of tales from the international repertoire of medieval stories have appeared in Russia in translations and adaptations. Among them the tales of King Solomon and the beast Kitovras (the Russian transliteration of the Greek Κένταυρος), folkloric apocrypha based on Biblical stories, were presented. These tales tell how King Solomon decided to build a temple in Jerusalem and needed the help of a “feet-footed beast”, a legendary centaur Kitovras. This half-man and half-beast, being a wizard and a prophet, appears as the king’s rival who is even wiser than Solomon himself. Besides, he possesses enormous physical strength, and he has a weakness for vine and women, which destroys him. From the end of the 16th century, medieval Italian and French adventure novels were translated into Russian from the German and Polish chapbooks versions. The Story of Prince Bova translated from Polish or Belarusian goes back through the Ragusa version to the Italian romance of Buovo d’Antona and finally to the Anglo-Norman Bevis of Hampton. This novel became extremely popular, and it acquired features of Russian folk tale depicted in numerous and cheap lubok prints. The main hero Prince Bova has an enemy Polkan, a half-human half-horse creature of enormous strength and speed, who, after the first battle with Bova, becomes his best friend and defender. De-etymologization of the Italian word Puli-cane (a half-dog) as a Polkan [Pol-kon’] creates a new hero whose name in Russian could mean a half-horse, and who looks like a centaur. Russian tales appear to fantastically reflect and contaminate too parallel traditions presenting centaurs since Antiquity: on the one hand, centaurs are savage, violent and destructive creatures; on the other hand, one of them, Chiron was the wise prophet and the educator of main ancient Greek heroes., The volume gathers the results of a stage of the programme Our Mythical Childhood, supported by an Alexander von Humboldt Foundation Alumni Award for Innovative Networking Initiatives and an ERC Consolidator Grant. Open Access at Universitätsverlag Winter GmbH at https://www.winter-verlag.de/en/detail/978-3-8253-7874-5/Marciniak_Ed_Chasing_Mythical_Beasts_PDF/ book/ hardcover ISBN: 978-3-8253-6995-8 Series: Studien zur europäischen Kinder- und Jugendliteratur/Studies in European Children's and Young Adult Literature, Volume No.: 8 Information about Our Mythical Childhood is available at http://omc.obta.al.uw.edu.pl/

Narrow and dense rings have been detected around the small Centaur body Chariklo (Braga-Ribas et al. 2014), as well as around the dwarf planet Haumea (Ortiz et al. 2017). Both objects have non-axisymmetric shapes that induce strong resonant effects between the rotating central body with spin rate Ω and the radial epicyclic motion of the ring particles, κ. These resonances include the classical Eccentric Lindblad Resonances (ELR), where κ = m(n-Ω), with m integer, n being the particle mean motion. These resonances create an exchange of angular momentum between the body and the collisional ring, clearing the corotation zone, pushing the inner disk onto the body and repelling the outer part outside of the outermost 1/2 ELR, where the particles complete one orbital revolution while the body executes two rotations, i.e. n/Ω ~ 1/2 (Sicardy et al. 2019) Here I will focus on higher-order resonances. They may appear either by considering other resonances such as n/Ω ~ 1/3, or the same resonance as above (n/Ω ~ 1/2), but with a body that has a triaxial shape. In this case, the invariance of the potential under a rotation of π radians transforms the 1st-order 1/2 Lindblad Resonance into a 2nd order 2/4 resonance. Second-order resonances are of particular interest because they force a strong response of the particles near the resonance radius, in spite of the intrinsically small strength of their forcing terms. This stems from the topography of the associated resonant Hamiltonian, which possesses an unstable hyperbolic point at its origin. The width of the region where this strong response is expected will be discussed for both Chariklo's and Haumea's rings. The special case of the second-order 1/3 resonance will be discussed, as it appears that both ring systems are close to that resonance. This work is intended, among others, to pave the way for future collisional simulations of rings around non-axisymmetric bodies. Braga-Ribas et al., 2014, Nature 508, 72Ortiz et al., 2017, Nature 550, 219Sicardy et al., 2019, Nature Astronomy 3, 146 The work leading to these results has received funding from the European Research Council under the European Community's H2020 2014-2020 ERC Grant Agreement n°669416 "Lucky Star"

Centaurs – planet-crossing bodies in the region of the giant planets that mainly originate in the Kuiper Belt/Scattered Disk [1, 2] – are thought to be the primary impactors on the giant planets and their satellites [3-8]. As part of an effort to interpret the cratering records of the saturnian satellites, we are developing a dynamical-physical model for the size distribution of potential impactors on the moons. Most models of the orbital distribution of "observable" comets[1] assume that the size of the nucleus does not change with time. These models treat physical evolution only by assuming a lifetime, after which comets are considered inactive or "faded". These models do not specify a fading mechanism, but assume an expression for the probability that a comet remains active after some amount of time [10-14]. Fading can result from loss of all volatiles, formation of a nonvolatile mantle on the surface of the nucleus, or splitting [15, 16]. A model of the erosion of 67P/Churyumov-Gerasimenko and 46P/Wirtanen due to sublimation of water ice throughout their orbital evolution estimates that 67P’s nucleus has shrunk from a radius of 2.5 km to 2 km, while 46P’s has decreased from 1 km to 0.6 km [17]. This calculation assumes that 10% of the nucleus is active and that its density is 500 kg/m3. These estimates are uncertain because comets follow chaotic orbits, but in general, erosion has a bigger effect on smaller nuclei. Some comets are active well beyond the water-ice sublimation zone within 3 au. Eighteen active Centaurs are currently known [18, 19]. 29P/Schwassmann-Wachmann, which follows a near-circular orbit at 6 au, is a copious source of dust and CO [20-22] and undergoes significant dust outbursts 7 or more times a year [23]. 174P/Echeclus underwent an outburst 13 au from the Sun that released ≈ 300 kg/s of dust for about two months [24], a rate comparable to the 530 kg/s of dust released by 67P at its peak near 1.3 au [25]. Echeclus also underwent several more outbursts near perihelion (≈6 au) with CO outgassing at ≈ 10% the rate of 29P at the same heliocentric distance and dust mass loss rates of 10 - 700 kg/s [20]. 2060 Chiron is another Centaur that is sporadically active in gas and dust, consistent with a more depleted state, like Echeclus [20]. Di Sisto et al. (2009) constructed a model of the orbital distributions of Jupiter-family comets (JFCs) that incorporated planetary perturbations, nongravitational forces, sublimation, and splitting. They considered nuclei with initial radii of 10, 5, and 1 km [26]. Di Sisto et al. found that 5- and 10-km comets usually evolved onto Centaur orbits, while 1-km comets were most likely to shrink below 100 m. Inspired by their work, we are developing a model for the dynamical-physical evolution of JFCs and Centaurs. We will use the orbital distribution found by Nesvorny et al. as our baseline model [14, 27]. We will first focus on modeling the evolution of the size distribution of JFCs. The model will eventually account for mass loss by both JFCs and Centaurs, with activity driven by H2O, CO, or other volatiles. The fraction of the nucleus that is active will be allowed to vary with size, since smaller nuclei are typically more active [28-30]. We will then implement a model for cometary splitting with these inputs: the frequency of splitting as a function of perihelion distance; the fraction of the comet’s mass released as fragments; the size distribution of the fragments; and the velocity imparted to the fragments by the splitting event. We will present preliminary results of our simulations. We thank Raphael Marschall for discussions and the Cassini Data Analysis Program for support. References [1] Volk, K.; Malhotra, R. ApJ 687, 714–725, 2008. [2] Di Sisto, R. P.; Rossignoli, N. L. CMDA, in press (arXiv:2006.09657), 2020. [3] Zahnle, K.; Dones, L.; Levison, H. F. Icarus 136, 202–222, 1998. [4] Zahnle, K.; Schenk, P.; Levison, H.; Dones, L. Icarus 163, 263–289, 2003. [5] Di Sisto, R. P.; Zanardi, M. A&A 553, id. A79, 2013. [6] Di Sisto, R. P.; Zanardi, M. Icarus 264, 90–101, 2016. [7] Rossignoli, N. L.; Di Sisto, R. P.; Zanardi, M.; Dugaro, A. A&A 627, id. A12, 2019. [8] Wong, E. W.; Brasser, R.; Werner, S. C. EPSL 506, 407–416, 2019. [9] Quinn, T.; Tremaine, S.; Duncan, M. ApJ 355, 667–679, 1990. [10] Oort, J. H. BAN 11, 91–110, 1950. [11] Levison, H. F.; Duncan, M. J. Icarus 127, 13–32, 1997. [12] Wiegert, P.; Tremaine, S. Icarus 137, 84–121, 1999. [13] Brasser, R.; Wang, J.-H. A&A 573, id. A102, 2015. [14] Nesvorný, D. et al. ApJ 845, id. 27, 2017. [15] Weissman, P. R.; Bottke, W. F., Jr.; Levison, H. F. In Asteroids III, Univ. Arizona Press, pp. 669–686, 2002. [16] Jewitt, D. C. In Comets II, Univ. Arizona Press, pp. 659–676, 2004. [17] Groussin, O. et al. MNRAS 376, 1399–1406, 2007. [18] Jewitt, D. AJ 137, 4296–4312, 2009. [19] Chandler, C. O. et al. ApJLett 892, id. L38, 2020. [20] Womack, M.; Sarid, G.; Wierzchos, K. PASP 129, 031001, 2017. [21] Sarid, G. et al. ApJLett 883, id. L25, 2019. [22] Wierzchos, K.; Womack, M. AJ 159, id. 136, 2020. [23] Trigo-Rodríguez, J. M. et al. MNRAS 409, 1682–1690, 2010. [24] Bauer, J. M. et al. PASP 120, 393–404, 2008. [25] Marschall, R. et al. Frontiers in Physics, doi: 10.3389/fphy.2020.00227 (arXiv:2005.13700), 2020. [26] Di Sisto, R. P.; Fernandez, J. A.; Brunini, A. Icarus 203, 140–154, 2009. [27] Nesvorný, D. et al. AJ 158, id. 132, 2019. [28] A’Hearn, M. F. et al. Science 332, 1396–1400, 2011. [29] Tancredi, G.; Fernandez, J. A.; Rickman, H.; Licandro, J. Icarus 182, 527–549, 2006. [30] Schleicher, D. G.; Knight, Matthew M. AJ 152, id. 89, 2016. [1] The simplest model used to compare simulated and observed orbital distributions assumes that comets that pass perihelion within a fixed distance from the Sun, such as 2.5 au, are "discovered" [9].

1 IntroductionCentaurs are objects that orbit the Sun with semi-major axis between those of Jupiter and Neptune, according to the JPL Horizons definition https://ssd.jpl.nasa.gov/sbdb_help.cgi?class=CEN. These objects are thought to come from the trans-Neptunian region being injected into inner parts of the solar system due to planetary encounters, mostly with Neptune [1]. Therefore, centaurs present an excellent opportunity to study smaller trans-Neptunian objects much closer to the Earth, providing a better characterization of their physical properties. During the last years, there has been a growing momentum in the interest about the centaur population due to the discovery of ring systems around two of them, Chariklo [2] and Chiron [3,4], which has opened a new branch of research in order to understand how such rings are formed and how they can survive around these small bodies.(54598) Bienor is one of the largest centaurs known to date, with a diameter of ∼ 200 km estimated from Herschel Space Observatory, Spitzer Space Telescope and ALMA thermal measurements [5,6], similar to that of Chiron and Chariklo. Bienor also has ellipsoidal shape and water ice spectral features analogous to Chariklo and Chiron [7,8,9], although its rotation period of ∼ 9.14 h, without being very slow, is slightly over the average of the TNO/centaur population [10]. From the similarities with Chariklo and Chiron and from other reasons it has been proposed that Bienor could possess a ring system, similar to what has been found in the above mentioned centaurs [9].2 ObservationsWithin our program of physical characterization of TNOs and centaurs, a stellar occultation by the centaur Bienor was predicted to occur on January 11, 2019, with good observability potential. High accuracy astrometry runs were carried out to refine the prediction, and as a result, a shadow path favorable for the south of Europe was derived. This encouraged us to carry out an occultation observation campaign that resulted in 5 positive detections from 4 observing sites located in Spain and Portugal (see Figure 1 and Figure 2). Apart from occultations by the centaurs Chiron [3,4], Chariklo [2,11,12] and 2002 GZ32 [13], no other multichord occultations by centaurs had ever been obtained. 3 ResultsFrom the analysis of the occultation chords we obtain the instantaneous limb fit of Bienor at the moment of the occultation and combining this information with rotational light curves obtained shortly after the occultation, we infer the rotational phase at the time of the occultation and the three dimensional shape of this Centaur under the assumption of a triaxial ellipsoidal shape. The area-equivalent diameter and geometric albedo are also derived and its mass density can be constrained under the assumption of hydrostatic equilibrium. Our results are compared with radiometric results obtained using Herschel Space Observatory, Spitzer Space Telescope and ALMA facilities. Besides, we explored the potential presence of a ring system and we found no clear hints for rings, but constraints on debris material orbiting Bienor will be presented.Acknowlegements: P.S-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 "LEO-SBNAF" (MCIU/AEI/FEDER, UE). We would like to acknowledge financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709) and the financial support by the Spanish grant AYA-2017-84637-R. This campaign was carried out within the “Lucky Star" umbrella that agglomerates the efforts of the Paris, Granada and Rio teams. It is funded by the European Research Council under the European Community’s H2020 (2014-2020/ERC Grant Agreement No. 669416). Part of the research leading to these results has received funding from the European Unions Horizon 2020 Research and Innovation Programme, under Grant Agreement No. 687378 (SBNAF). E.F-V acknowledges UCF 2017 Preeminent Postdoctoral Program (P3). F.L.R is thankful for the support of the CAPES scholarship.References[1] Fernandez J. A., 1980, MNRAS, 192, 481[2] Braga-Ribas F., Sicardy, B., Ortiz, J. L., et al., 2014, Nature, 508, 72[3] Ortiz J. L., Duffard, R., Pinilla-Alonso, N., et al., 2015, A&A, 576, A18[4] Ruprecht J. D., Bosh A. S., Person M. J., et al., 2015, Icarus, 252, 271[5] Duffard R., Pinilla-Alonso N., Santos-Sanz P., et al., 2014, A&A, 564, A92[6] Lellouch E., Moreno R., Müller T., et al., 2017, A&A, 608, A45[7] Dotto E., Barucci M. A., Boehnhardt H., et al., 2003, Icarus, 162, 408[8] Rabinowitz D. L., Schaefer B. E., Tourtellotte S. W., 2007, AJ, 133, 26[9] Fernández-Valenzuela E., Ortiz J. L., Duffard R. et al., 2017, MNRAS, 466, 4147[10] Thirouin A., Noll K. S., Ortiz J. L., Morales N., 2014, A&A, 569, A3[11] Bérard D., Sicardy B., Camargo J.I.B., et al., 2017, AJ, 154, 144[12] Leiva R., Sicardy B., Camargo J.I.B., et al., 2017, AJ, 154, 159[13] Santos-Sanz P., Ortiz J. L., Sicardy B., at al., submitted to MNRAS

In two recent papers published in MNRAS, Namouni and Morais (2018, 2020) claimed evidence for the interstellar origin of some small Solar System bodies, including i) objects in retrograde co-orbital motion with the giant planets, and ii) the highly-inclined Centaurs. Here, we discuss the flaws of those papers that invalidate the authors' conclusions. Numerical simulations backwards in time are not representative of the past evolution of real bodies. Instead, these simulations are only useful as a means to quantify the short dynamical lifetime of the considered bodies and the fast decay of their population. In light of this fast decay, if the observed bodies were the survivors of populations of objects captured from interstellar space in the early Solar System, these populations should have been implausibly large (e.g. about 10 times the current main asteroid belt population for the retrograde coorbital of Jupiter). More likely, the observed objects are just transient members of a population that is maintained in quasi-steady state by a continuous flux of objects from some parent reservoir in the distant Solar System. We identify in the Halley type comets and the Oort cloud the most likely sources of retrograde coorbitals and highly-inclined Centaurs., Comment: in press in MNRAS

The current giant planet region is a transitional zone where transneptunian objects (TNOs) cross in their way to becoming Jupiter Family Comets (JFCs). Their dynamical behavior is conditioned by the intrinsic dynamical features of TNOs and also by the encounters with the giant planets. We address the Giant Planet Crossing (GPC) population (those objects with $5.2$ au $ < q < 30$ au) studying their number and their evolution from their sources, considering the current configuration of the Solar System. This subject is reviewed from previous investigations and also addressed by new numerical simulations of the dynamical evolution of Scattered Disk Objects (SDOs). We obtain a model of the intrinsic orbital element distribution of GPCs. The Scattered Disk represents the main source of prograde GPCs and Centaurs, while the contribution from Plutinos lies between one and two orders of magnitude below that from the SD. We obtain the number and size distribution of GPCs from our model, computing 9600 GPCs from the SD with $D > 100$ km and $\sim 10^8$ with $D > 1$ km in the current population. The contribution from other sources is considered negligible. The mean lifetime in the Centaur zone is 7.2 Myr, while the mean lifetime of SDOs in the GPC zone is of 68 Myr. The latter is dependent on the initial inclination, being the ones with high inclinations the ones that survive the longest in the GPC zone. There is also a correlation of lifetime with perihelion distance, where greater perihelion leads to longer lifetime. The dynamical evolution of observed GPCs is different for prograde and retrograde objects. Retrograde GPCs have lower median lifetime than prograde ones, thus experiencing a comparatively faster evolution. However, it is probable that this faster evolution is due to the fact that the majority of retrograde GPCs have low perihelion values and then, lower lifetimes., 39 pages, 15 figures. Accepted por publication in Celestial Mechanics and Dynamical Astronomy (June 2020)

Funded by the Robert Martin Ayers Sciences Fund and NSF AST-1412587. We observed the 2020 February 4th outburst of the Centaur 29P/Schwassmann-Wachmann, using the James Gregory Telescope in St Andrews/UK. The brightness of the comet increased by ∼3 mag in VRI within 1-2 days, followed by a more gradual incline. This was one of the largest documented outbursts of this object over the past few years, but is consistent with previously observed events. Postprint Non

29P/Schwassmann Wachmann is an unusual solar system object. Originally classified as a short-period comet, it is now known as a Centaur that recently transferred to its current orbit, and may become a Jupiter Family comet. It has exhibited a dust coma for over 90 years, and regularly undergoes significant dust outbursts. Carbon monoxide is routinely detected in high amounts and is typically assumed to play a large role in generating the quiescent dust coma and outbursts. To test this hypothesis, we completed two 3-month long observing campaigns of the CO J=2-1 rotational line using the Arizona Radio Observatory 10m Sub-millimeter Telescope during 2016 and 2018-2019, and compared the results to visible magnitudes obtained at the same time. As the Centaur approached its 2019 perihelion, the quiescent dust coma grew $\sim$45\% in brightness, while it is unclear whether the quiescent CO production rate also increased. A doubling of the CO production rate on 2016 Feb 28.6 UT did not trigger an outburst nor a rise in dust production for at least 10 days. Similarly, two dust outbursts occurred in 2018 while CO production continued at quiescent rates. Two other dust outbursts may show gas involvement. The data indicate that CO- and dust-outbursts are not always well-correlated. This may be explained if CO is not always substantially incorporated with the dust component in the nucleus, or if CO is primarily released through a porous material. Additionally, other minor volatiles or physical processes may help generate dust outbursts., Accepted for publication in The Astronomical Journal