BUSCADOR RECOLECTA

This work focuses on the analysis of some of the brightest bolides recorded along February 2021 by the meteorobserving stations operating in the framework of the Southwestern Europe Meteor Network (SWEMN). Some of them were produced by meteoroids belonging to recently discovered and poorly-known streams. The absolute magnitude of these fireballs, which were observed over the Iberian Peninsula, ranged between ±7 and ±10. The
emission spectra produced by some of these events are also presented and discussed., Spanish Ministry of Science and Innovation (project PID2019-105797GB-I00). State Agency for Research of the Spanish MCIU through the 'Center of Excellence Severo Ochoa' award of the Instituto de Astrofísica de Andalucía (SEV-2017-0709). P.S-S. acknowledges financial support by the Spanish grant AYA- RTI2018-098657-J-I00 'LEO-SBNAF' (MCIU / AEI / FEDER, UE).

Some of the remarkable bolides spotted in the framework of the Southwestern Europe Meteor Network from March to May 2022 are described here. These have been observed from the Iberian Peninsula. Their absolute magnitude ranges from -8 to -15. The emission spectrum of one of them is also analyzed. Bright meteors included in this report were linked to different sources: the sporadic background, major meteoroid streams, and poorly-known streams., We acknowledge support from the Spanish Ministry of Science and Innovation (project PID2019-105797GB-I00). We also acknowledge financial support from the State Agency for Research of the Spanish MCIU through the 'Center of Excellence Severo Ochoa' award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709). P.S-S. acknowledges financial support by the Spanish grant AYA-RTI2018¿098657-J-I00 'LEO-SBNAF' (MCIU / AEI / FEDER, UE).

The goal of Project GAUSS (Genesis of Asteroids and evolUtion of the Solar System) is to return samples from the dwarf planet Ceres. Ceres is the most accessible candidate of ocean worlds and the largest reservoir of water in the inner Solar System. It shows active volcanism and hydrothermal activities in recent history. Recent evidence for the existence of a subsurface ocean on Ceres and the complex geochemistry suggest past habitability and even the potential for ongoing habitability. GAUSS will return samples from Ceres with the aim of answering the following top-level scientific questions: - What is the origin of Ceres and what does this imply for the origin of water and other volatiles in the inner Solar System? - What are the physical properties and internal structure of Ceres? What do they tell us about the evolutionary and aqueous alteration history of dwarf planets? - What are the astrobiological implications of Ceres? Is it still habitable today? - What are the mineralogical connections between Ceres and our current collections of carbonaceous meteorites?, Part of this work has been carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). J.-Y.L. acknowledges partial support from the Solar System Exploration Research Virtual Institute 2016 (SSERVI16) Cooperative Agreement (grant NNH16ZDA001N), SSERVI-TREX to the Planetary Science Institute. J.A. acknowledges support from the European Research Council Starting Grant 757390 (CAstRA). A.J.C. and G.H.J. acknowledge support from the STFC consolidated grant to UCL-MSSL STS0002401. P. Santos-Sanz, and R. Duffard acknowledges financial support by the Spanish grant AYA- RTI2018-098657-J-I00 ’LEO-SBNAF’ (MCIU/AEI/FEDER, UE). J.L. Ortiz, P. Santos-Sanz, and R. Duffard 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). J.M.T-R. acknowledges support from the Spanish Ministry of Science and Innovation (project PGC2018-097374-B-I00). J.M.T-R.’s research has been funded by the research project (PGC2018-097374-B-I00), funded by FEDER/Ministerio de Ciencia e Innovación – Agencia Estatal de Investigación.

Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Open Access funding provided by Max Planck Society., Non-resolved thermal infrared observations enable studies of thermal and physical properties of asteroids via thermo-physical models provided the shape and rotational properties of the target are well determined. We used calibration-programme Herschel PACS data (70, 100, 160 μm) and state-of-the-art shape models derived from adaptive-optics observations and/or optical light curves to constrain for the first time the thermal inertia of twelve large main-belt asteroids. We also modelled previously well-characterised targets such as (1) Ceres or (4) Vesta as they constitute important benchmarks. Using the scale as a free parameter, most targets required a re-scaling ∼5% consistent with what would be expected given the absolute calibration error bars. This constitutes a good cross-validation of the scaled shape models, although some targets required larger re-scaling to reproduce the IR data. We obtained low thermal inertias typical of large main belt asteroids studied before, which continues to give support to the notion that these surfaces are covered by fine-grained insulating regolith. Although the wavelengths at which PACS observed are longwards of the emission peak for main-belt asteroids, they proved to be extremely valuable to constrain size and thermal inertia and not too sensitive to surface roughness. Finally, we also propose a graphical approach to help examine how different values of the exponent used for scaling the thermal inertia as a function of heliocentric distance (i.e. temperature) affect our interpretation of the results. © V. Alí-Lagoa et al. 2020., The research leading to these results has received funding from the European Union's Horizon 2020 Research and Innovation Programme, under Grant Agreement number 687378 (SBNAF). C.K., R.S., A.F-T., and G.M. have been supported by the K-125015 and GINOP-2.3.2-15-2016-00003 grants of the National Research, Development and Innovation Office (NKFIH), Hungary. P.S-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 (MCIU/AEI/FEDER, UE). R.D. and P.S-S. 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 Astrofiica de Andalucia (SEV-2017-0709); they also acknowledge financial support by the Spanish grant AYA-2017-84637-R and the Proyecto de Excelencia de la Junta de Andalucia J.A. 2012-FQM1776., Peer reviewed

Full list of authors: Souami, D.; Braga-Ribas, F.; Sicardy, B.; Morgado, B.; Ortiz, J. L.; Desmars, J.; Camargo, J. I. B.; Vachier, F.; Berthier, J.; Carry, B.; Anderson, C. J.; Showers, R.; Thomason, K.; Maley, P. D.; Thomas, W.; Buie, M. W.; Leiva, R.; Keller, J. M.; Vieira-Martins, R.; Assafin, M.; Santos-Sanz, P.; Morales, N.; Duffard, R.; Benedetti-Rossi, G.; Gomes-Júnior, A. R.; Boufleur, R.; Pereira, C. L.; Margoti, G.; Pavlov, H.; George, T.; Oesper, D.; Bardecker, J.; Dunford, R.; Kehrli, M.; Spencer, C.; Cota, J. M.; Garcia, M.; Lara, C.; McCandless, K. A.; Self, E.; Lecacheux, J.; Frappa, E.; Dunham, D.; Emilio, M. .--Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Context. We present results from the first recorded stellar occultation by the large trans-Neptunian object (174567) Varda that was observed on September 10, 2018. Varda belongs to the high-inclination dynamically excited population, and has a satellite, Ilmarë, which is half the size of Varda. Aims. We determine the size and albedo of Varda and constrain its 3D shape and density. Methods. Thirteen different sites in the USA monitored the event, five of which detected an occultation by the main body. A best-fitting ellipse to the occultation chords provides the instantaneous limb of the body, from which the geometric albedo is computed. The size and shape of Varda are evaluated, and its bulk density is constrained using Varda's mass as is known from previous works. Results. The best-fitting elliptical limb has semi-major (equatorial) axis of (383 ± 3) km and an apparent oblateness of 0.066 ± 0.047, corresponding to an apparent area-equivalent radius R′equiv = (370±7) km and geometric albedo pv = 0.099 ± 0.002 assuming a visual absolute magnitude HV = 3.81 ± 0.01. Using three possible rotational periods for the body (4.76, 5.91, and 7.87 h), we derive corresponding MacLaurin solutions. Furthermore, given the low-amplitude (0.06 ± 0.01) mag of the single-peaked rotational light-curve for the aforementioned periods, we consider the double periods. For the 5.91 h period (the most probable) and its double (11.82 h), we find bulk densities and true oblateness of ρ = (1.78 ± 0.06) g cm-3, ϵ = 0.235 ± 0.050, and ρ = (1.23 ± 0.04) g cm-3, ϵ = 0.080 ± 0.049. However, it must be noted that the other solutions cannot be excluded just yet. © D. Souami et al. 2020., 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). The following authors acknowledge the respective CNPq grants: F.B.-R. 309578/2017-5; R.V.M. 304544/2017-5, 401903/2016-8; J.I.B.C. 308150/2016-3 and 305917/2019-6; M.A. 427700/2018-3, 310683/2017-3, 473002/2013-2. This study was financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior -Brasil (CAPES) -Finance Code 001 and the National Institute of Science and Technology of the e-Universe project (INCT do e-Universo, CNPq grant 465376/2014-2). G.B.R. acknowledges CAPES-FAPERJ/PAPDRJ grant E26/203.173/2016, MA FAPERJ grant E-26/111.488/2013 and ARGJr FAPESP grant 2018/11239-8. J.L.O., P.S.-S., N.M., and R.D. 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). P.S.-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 "LEO-SBNAF" (MCIU/AEI/FEDER, UE). Observations from the RECON network were provided by students, teachers, and community members, including Xavier Banaga, Jesus Bustos, Amanda Carrillo, Dorey W. Conway, Kenneth Conway, Danielle D. Laguna, Andrew E. McCandless, Kaitlin McArdle, and Jared T. White, Jr. The observers listed in this paper are but a small fraction of the total RECON network and their dedication to this project is deeply appreciated. Funding for RECON was provided by grants from NSF AST-1413287, AST-1413072, AST-1848621, and AST-1212159. 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. This research has made use of the VizieR catalogue access tool, CDS, Strasbourg, France (DOI: 10.26093/cds/vizier). The original description of the VizieR service was published in Ochsenbein et al. (2000)., Peer reviewed

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., Peer reviewed

Full list of authors: Morgado, B. E.; Sicardy, B.; Braga-Ribas, F.; Desmars, J.; Gomes-Júnior, A. R.; Bérard, D.; Leiva, R.; Ortiz, J. L.; Vieira-Martins, R.; Benedetti-Rossi, G.; Santos-Sanz, P.; Camargo, J. I. B.; Duffard, R.; Rommel, F. L.; Assafin, M.; Boufleur, R. C.; Colas, F.; Kretlow, M.; Beisker, W.; Sfair, R.; Snodgrass, C.; Morales, N.; Fernández-Valenzuela, E.; Amaral, L. S.; Amarante, A.; Artola, R. A.; Backes, M.; Bath, K. -L.; Bouley, S.; Buie, M. W.; Cacella, P.; Colazo, C. A.; Colque, J. P.; Dauvergne, J. -L.; Dominik, M.; Emilio, M.; Erickson, C.; Evans, R.; Fabrega-Polleri, J.; Garcia-Lambas, D.; Giacchini, B. L.; Hanna, W.; Herald, D.; Hesler, G.; Hinse, T. C.; Jacques, C.; Jehin, E.; Jørgensen, U. G.; Kerr, S.; Kouprianov, V.; Levine, S. E.; Linder, T.; Maley, P. D.; Machado, D. I.; Maquet, L.; Maury, A.; Melia, R.; Meza, E.; Mondon, B.; Moura, T.; Newman, J.; Payet, T.; Pereira, C. L.; Pollock, J.; Poltronieri, R. C.; Quispe-Huaynasi, F.; Reichart, D.; de Santana, T.; Schneiter, E. M.; Sieyra, M. V.; Skottfelt, J.; Soulier, J. F.; Starck, M.; Thierry, P.; Torres, P. J.; Trabuco, L. L.; Unda-Sanzana, E.; Yamashita, T. A. R.; Winter, O. C.; Zapata, A.; Zuluaga, C. A.--This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Context. The Centaur (10199) Chariklo has the first ring system discovered around a small object. It was first observed using stellar occultation in 2013. Stellar occultations allow sizes and shapes to be determined with kilometre accuracy, and provide the characteristics of the occulting object and its vicinity. Aims. Using stellar occultations observed between 2017 and 2020, our aim is to constrain the physical parameters of Chariklo and its rings. We also determine the structure of the rings, and obtain precise astrometrical positions of Chariklo. Methods. We predicted and organised several observational campaigns of stellar occultations by Chariklo. Occultation light curves were measured from the datasets, from which ingress and egress times, and the ring widths and opacity values were obtained. These measurements, combined with results from previous works, allow us to obtain significant constraints on Chariklo's shape and ring structure. Results. We characterise Chariklo's ring system (C1R and C2R), and obtain radii and pole orientations that are consistent with, but more accurate than, results from previous occultations. We confirm the detection of W-shaped structures within C1R and an evident variation in radial width. The observed width ranges between 4.8 and 9.1 km with a mean value of 6.5 km. One dual observation (visible and red) does not reveal any differences in the C1R opacity profiles, indicating a ring particle size larger than a few microns. The C1R ring eccentricity is found to be smaller than 0.022 (3σ), and its width variations may indicate an eccentricity higher than ~0.005. We fit a tri-axial shape to Chariklo's detections over 11 occultations, and determine that Chariklo is consistent with an ellipsoid with semi-axes of 143.8-1.5+1.4, 135.2-2.8+1.4, and 99.1-2.7+5.4 km. Ultimately, we provided seven astrometric positions at a milliarcsecond accuracy level, based on Gaia EDR3, and use it to improve Chariklo's ephemeris. © B. E. Morgado et al. 2021., This work was carried out within the “Lucky Star” umbrella that agglomerates the efforts of the Paris, Granada and Rio teams, which is funded by the European Research Council under the European Community’s H2020 (ERC Grant Agreement No. 669416). This research made use of SORA, a python package for stellar occultations reduction and analysis, developed with the support of ERC Lucky Star and LIneA/Brazil, within the collaboration Rio-Paris-Granada teams. 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). Part of this research is suported by INCT do e-Universo, Brazil (CNPQ grants 465376/2014-2). Based in part on observations made at the Laboratório Nacional de Astrofísica (LNA), Itajubá-MG, Brazil. The data include observations taken by the MiNDSTEp team at the Danish 1.54 m telescope at ESO’s La Silla observatory” and “UGJ acknowledges funding from the European Union H2020-MSCA-ITN-2019 under grant no. 860470 (CHAMELEON) and from the Novo Nordisk Foundation Interdisciplinary Synergy Programme grant no. NNF19OC0057374. TRAPPIST-South is funded by the Belgian Fund for Scientific Research (Fond National de la Recherche Scientifique, FNRS) under the grant PDR T.0120.21. The authors acknowledge the use of Sonja Itting-Enke’s C14 telescope and the facilities at the Cuno Hoffmeister Memorial Observatory (CHMO). The following authors acknowledge the respective CNPq grants: BEM 150612/2020-6; FB-R 314772/2020-0; RV-M 304544/2017-f5, 401903/2016-8; JIBC 308150/2016-3 and 305917/2019-6; MA 427700/2018-3, 310683/2017-3, 473002/2013-2. G.B.R. acknowledges CAPES-FAPERJ/PAPDRJ grant E26/203.173/2016 and CAPES-PRINT/UNESP grant 88887.571156/2020-00, MA FAPERJ grant E-26/111.488/2013 and ARGJr FAPESP grant 2018/11239-8. J.L.O., P.S.-S., R.D., and N.M. acknowledge financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709), from Spanish project AYA2017-89637-R, and from FEDER. P.S.-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 “LEO-SBNAF” (MCIU/AEI/FEDER, UE). E. Jehin is a Belgian FNRS Senior Research Associate. R.S. and O.C.W. acknowledge FAPESP grant 2016/24561-0 and CNPq grant 305210/2018-1. T.C.H. acknowledges financial support from the National Research Foundation (NRF; No. 2019R1I1A1A01059609)., Peer reviewed

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., A stellar occultation by Pluto was observed on 2020 June 6 with the 1.3 m and 3.6 m telescopes located at Devasthal, Nainital, India, using imaging systems in the I and H bands, respectively. From this event, we derive a surface pressure for Pluto's atmosphere of psurf=12.23-0.38+0.65 μbar. This shows that Pluto's atmosphere has been in a plateau phase since mid-2015, a result which is in excellent agreement with the Pluto volatile transport model of Meza et al. This value does not support the pressure decrease reported by independent teams, based on occultations observed in 2018 and 2019 by Young et al. and Arimatsu et al., respectively. © 2021. The Author(s). Published by the American Astronomical Society., The authors are grateful to the Directors of ARIES and IIA for granting time under Directors' Discretionary Time allotment for observing this event. The authors also thank the staff of the Devasthal Observatory and the IR Group at TIFR for their help during observations. The work leading to these results has received funding from the European Research Council under the European Community's H2020 2014-2021 ERC Grant Agreement no. 669416 "Lucky Star." Research at PRL and IIST is supported by the Department of Space, Government of India. M.A., G.B.-R., F.B.-R., and R.V.-M. thank CNPq and CAPES for grants 313144/2020-6, 314772/2020-0, 465376/2014-2, and Process 88887.310463/2018-00—Project 88887.571156/2020-00. R.V.-M. also thanks grant CNPq 304544/2017-6. P.S-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 "LEO-SBNAF" (MCIU/AEI/FEDER, UE)., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709., Peer reviewed

Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Context. The recently announced Oort-cloud comet C/2014 UN271 (Bernardinelli-Bernstein) is remarkable in at least three respects: (i) it was discovered inbound as far as 29 au from the Sun (with prediscovery images up to 34 au); (ii) it already showed cometary activity at almost 24 au; and (iii) its nuclear magnitude (Hr 8.0) indicates an exceptionally large object. Detection of gases is expected in the upcoming years as the comet heads toward a perihelion of 11 au in 2031. Aims. The goal is to determine the objecta s diameter and albedo from thermal measurements. Methods. We used ALMA in extended configuration (resolution 0.064a) to measure the 1287 μm (233 GHz) continuum flux of the comet. Observations were performed on August 8, 2021, at a 20.0 au distance from the Sun. The high spatial resolution was chosen in order to filter out any dust contribution. We also used a recently published Afρ value to estimate the dust production rate and the expected dust thermal signal for various assumptions on particle size distribution. Results. We detected the thermal emission of the object at 10I, with a flux of 0.128 ± 0.012 mJy. Based on observational constraints and our theoretical estimates of the dust contribution, the entirety of the measured flux can be attributed to the nucleus. From NEATM modeling combined with the Hr magnitude, we determine a surface-equivalent diameter of 137 ± 17 km and a red geometric albedo of 5.3 ± 1.2%. This confirms that C/2014 UN271 is by far the largest Oort-cloud object ever found (almost twice as large as comet C/1995 O1 Hale-Bopp) and, except for the Centaur 95P/Chiron, which shows outburst-like activity, the largest known comet in the Solar System. On the other hand, the C/2014 UN271 albedo is typical of comets, adding credence to a a universalacomet nucleus albedo. Conclusions. With its distant perihelion and uniquely large size, C/2014 UN271 (Bernardinelli-Bernstein) is the prominent archetype of distant comets whose activity is driven by hypervolatiles. Monitoring of dust and gas emission as the comet approaches and passes perihelion will permit its activity time pattern to be studied and compared to the distant (outbound) activity of Hale-Bopp. Post-perihelion thermal measurements will permit the study of possible albedo changes, such as a surface brightening compared to pre-perihelion, as was observed for Hale-Bopp. © E. Lellouch et al. 2022., This paper is based on ALMA program 2019.A.00038. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. P.S-S. acknowledges financial support from the Spanish grant AYA-RTI2018-098657-J-I00 “LEO-SBNAF” (MCIU/AEI/FEDER, UE) and from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709)., Peer reviewed

Full list of authors: Marques Oliveira, J.; Sicardy, B.; Gomes-Júnior, A. R.; Ortiz, J. L.; Strobel, D. F.; Bertrand, T.; Forget, F.; Lellouch, E.; Desmars, J.; Bérard, D.; Doressoundiram, A.; Lecacheux, J.; Leiva, R.; Meza, E.; Roques, F.; Souami, D.; Widemann, T.; Santos-Sanz, P.; Morales, N.; Duffard, R.; Fernández-Valenzuela, E.; Castro-Tirado, A. J.; Braga-Ribas, F.; Morgado, B. E.; Assafin, M.; Camargo, J. I. B.; Vieira-Martins, R.; Benedetti-Rossi, G.; Santos-Filho, S.; Banda-Huarca, M. V.; Quispe-Huaynasi, F.; Pereira, C. L.; Rommel, F. L.; Margoti, G.; Dias-Oliveira, A.; Colas, F.; Berthier, J.; Renner, S.; Hueso, R.; Pérez-Hoyos, S.; Sánchez-Lavega, A.; Rojas, J. F.; Beisker, W.; Kretlow, M.; Herald, D.; Gault, D.; Bath, K. -L.; Bode, H. -J.; Bredner, E.; Guhl, K.; Haymes, T. V.; Hummel, E.; Kattentidt, B.; Klös, O.; Pratt, A.; Thome, B.; Avdellidou, C.; Gazeas, K.; Karampotsiou, E.; Tzouganatos, L.; Kardasis, E.; Christou, A. A.; Xilouris, E. M.; Alikakos, I.; Gourzelas, A.; Liakos, A.; Charmandaris, V.; Jelínek, M.; Štrobl, J.; Eberle, A.; Rapp, K.; Gährken, B.; Klemt, B.; Kowollik, S.; Bitzer, R.; Miller, M.; Herzogenrath, G.; Frangenberg, D.; Brandis, L.; Pütz, I.; Perdelwitz, V.; Piehler, G. M.; Riepe, P.; von Poschinger, K.; Baruffetti, P.; Cenadelli, D.; Christille, J. -M.; Ciabattari, F.; Di Luca, R.; Alboresi, D.; Leto, G.; Zanmar Sanchez, R.; Bruno, P.; Occhipinti, G.; Morrone, L.; Cupolino, L.; Noschese, A.; Vecchione, A.; Scalia, C.; Lo Savio, R.; Giardina, G.; Kamoun, S.; Barbosa, R.; Behrend, R.; Spano, M.; Bouchet, E.; Cottier, M.; Falco, L.; Gallego, S.; Tortorelli, L.; Sposetti, S.; Sussenbach, J.; Van Den Abbeel, F.; André, P.; Llibre, M.; Pailler, F.; Ardissone, J.; Boutet, M.; Sanchez, J.; Bretton, M.; Cailleau, A.; Pic, V.; Granier, L.; Chauvet, R.; Conjat, M.; Dauvergne, J. L.; Dechambre, O.; Delay, P.; Delcroix, M.; Rousselot, L.; Ferreira, J.; Machado, P.; Tanga, P.; Rivet, J. -P.; Frappa, E.; Irzyk, M.; Jabet, F.; Kaschinski, M.; Klotz, A.; Rieugnie, Y.; Klotz, A. N.; Labrevoir, O.; Lavandier, D.; Walliang, D.; Leroy, A.; Bouley, S.; Lisciandra, S.; Coliac, J. -F.; Metz, F.; Erpelding, D.; Nougayrède, P.; Midavaine, T.; Miniou, M.; Moindrot, S.; Morel, P.; Reginato, B.; Reginato, E.; Rudelle, J.; Tregon, B.; Tanguy, R.; David, J.; Thuillot, W.; Hestroffer, D.; Vaudescal, G.; Baba Aissa, D.; Grigahcene, Z.; Briggs, D.; Broadbent, S.; Denyer, P.; Haigh, N. J.; Quinn, N.; Thurston, G.; Fossey, S. J.; Arena, C.; Jennings, M.; Talbot, J.; Alonso, S.; Román Reche, A.; Casanova, V.; Briggs, E.; Iglesias-Marzoa, R.; Abril Ibáñez, J.; Díaz Martín, M. C.; González, H.; Maestre García, J. L.; Marchant, J.; Ordonez-Etxeberria, I.; Martorell, P.; Salamero, J.; Organero, F.; Ana, L.; Fonseca, F.; Peris, V.; Brevia, O.; Selva, A.; Perello, C.; Cabedo, V.; Gonçalves, R.; Ferreira, M.; Marques Dias, F.; Daassou, A.; Barkaoui, K.; Benkhaldoun, Z.; Guennoun, M.; Chouqar, J.; Jehin, E.; Rinner, C.; Lloyd, J.; El Moutamid, M.; Lamarche, C.; Pollock, J. T.; Caton, D. B.; Kouprianov, V.; Timerson, B. W.; Blanchard, G.; Payet, B.; Peyrot, A.; Teng-Chuen-Yu, J. -P.; Françoise, J.; Mondon, B.; Payet, T.; Boissel, C.; Castets, M.; Hubbard, W. B.; Hill, R.; Reitsema, H. J.; Mousis, O.; Ball, L.; Neilsen, G.; Hutcheon, S.; Lay, K.; Anderson, P.; Moy, M.; Jonsen, M.; Pink, I.; Walters, R.; Downs, B.--This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Context. A stellar occultation by Neptune’s main satellite, Triton, was observed on 5 October 2017 from Europe, North Africa, and the USA. We derived 90 light curves from this event, 42 of which yielded a central flash detection. Aims. We aimed at constraining Triton’s atmospheric structure and the seasonal variations of its atmospheric pressure since the Voyager 2 epoch (1989). We also derived the shape of the lower atmosphere from central flash analysis. Methods. We used Abel inversions and direct ray-tracing code to provide the density, pressure, and temperature profiles in the altitude range ~8 km to ~190 km, corresponding to pressure levels from 9 µbar down to a few nanobars. Results. (i) A pressure of 1.18 ± 0.03 µbar is found at a reference radius of 1400 km (47 km altitude). (ii) A new analysis of the Voyager 2 radio science occultation shows that this is consistent with an extrapolation of pressure down to the surface pressure obtained in 1989. (iii) A survey of occultations obtained between 1989 and 2017 suggests that an enhancement in surface pressure as reported during the 1990s might be real, but debatable, due to very few high S/N light curves and data accessible for reanalysis. The volatile transport model analysed supports a moderate increase in surface pressure, with a maximum value around 2005-2015 no higher than 23 µbar. The pressures observed in 1995-1997 and 2017 appear mutually inconsistent with the volatile transport model presented here. (iv) The central flash structure does not show evidence of an atmospheric distortion. We find an upper limit of 0.0011 for the apparent oblateness of the atmosphere near the 8 km altitude. © J. Marques Oliveira et al. 2022., J.M.O. acknowledges financial support from the Portuguese Foundation for Science and Technology (FCT) and the European Social Fund (ESF) through the PhD grant SFRH/BD/131700/2017. The work leading to these results has received funding from the European Research Council under the European Community’s H2020 2014-2021 ERC grant Agreement n° 669416 “Lucky Star”. We thank S. Para who supported some travels to observe the 5 October 2017 occultation. T.B. was supported for this research by an appointment to the National Aeronautics and Space Administration (NASA) Post-Doctoral Program at the Ames Research Center administered by Universities Space Research Association (USRA) through a contract with NASA. We acknowledge useful exchanges with Mark Gurwell on the ALMA CO observations. 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. J.L.O., P.S.-S., N.M. and R.D. acknowledge financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (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 Andalucía J.A. 2012-FQM1776. 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). P.S.-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 “LEO-SBNAF”. The work was partially based on observations made at the Laboratório Nacional de Astrofísica (LNA), Itajubá-MG, Brazil. The following authors acknowledge the respective CNPq grants: F.B.-R. 309578/2017-5; R.V.-M. 304544/2017-5, 401903/2016-8; J.I.B.C. 308150/2016-3 and 305917/2019-6; M.A. 427700/20183, 310683/2017-3, 473002/2013-2. This study was financed in part by the Coor-denação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001 and the National Institute of Science and Technology of the e-Universe project (INCT do e-Universo, CNPq grant 465376/2014-2). G.B.R. acknowledges CAPES-FAPERJ/PAPDRJ grant E26/203.173/2016 and CAPES-PRINT/UNESP grant 88887.571156/2020-00, M.A. FAPERJ grant E-26/111.488/2013 and A.R.G.Jr. FAPESP grant 2018/11239-8. B.E.M. thanks CNPq 150612/2020-6 and CAPES/Cofecub-394/2016-05 grants. Part of the photometric data used in this study were collected in the frame of the photometric observations with the robotic and remotely controlled telescope at the University of Athens Observatory (UOAO; Gazeas 2016). The 2.3 m Aristarchos telescope is operated on Helmos Observatory by the Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing of the National Observatory of Athens. Observations with the 2.3 m Aristarchos telescope were carried out under OPTI-CON programme. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 730890. This material reflects only the authors views and the Commission is not liable for any use that may be made of the information contained therein. The 1.2 m Kryoneri telescope is operated by the Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing of the National Observatory of Athens. The Astronomical Observatory of the Autonomous Region of the Aosta Valley (OAVdA) is managed by the Fondazione Clément Fillietroz-ONLUS, which is supported by the Regional Government of the Aosta Valley, the Town Municipality of Nus and the “Unité des Communes valdôtaines Mont-Émilius”. The 0.81 m Main Telescope at the OAVdA was upgraded thanks to a Shoemaker NEO Grant 2013 from The Planetary Society. D.C. and J.M.C. acknowledge funds from a 2017 ‘Research and Education’ grant from Fondazione CRT-Cassa di Risparmio di Torino. P.M. acknowledges support from the Portuguese Fun-dação para a Ciência e a Tecnologia ref. PTDC/FISAST/29942/2017 through national funds and by FEDER through COMPETE 2020 (ref. POCI010145 FEDER007672). F.J. acknowledges Jean Luc Plouvier for his help. S.J.F. and C.A. would like to thank the UCL student support observers: Helen Dai, Elise Darragh-Ford, Ross Dobson, Max Hipperson, Edward Kerr-Dineen, Isaac Langley, Emese Meder, Roman Gerasimov, Javier Sanjuan, and Manasvee Saraf. We are grateful to the CAHA, OSN and La Hita Observatory staffs. This research is partially based on observations collected at Centro Astronómico Hispano-Alemán (CAHA) at Calar Alto, operated jointly by Junta de Andalucía and Consejo Superior de Investigaciones Científicas (IAA-CSIC). This research was also partially based on observation carried out at the Observatorio de Sierra Nevada (OSN) operated by Instituto de Astrofísica de Andalucía (CSIC). This article is also based on observations made with the Liverpool Telescope operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. Partially based on observations made with the Tx40 and Excalibur telescopes at the Observatorio Astrofísico de Javalambre in Teruel, a Spanish Infraestructura Cientifico-Técnica Singular (ICTS) owned, managed and operated by the Centro de Estudios de Física del Cosmos de Aragón (CEFCA). Tx40 and Excalibur are funded with the Fondos de Inversiones de Teruel (FITE). A.R.R. would like to thank Gustavo Román for the mechanical adaptation of the camera to the telescope to allow for the observation to be recorded. R.H., J.F.R., S.P.H. and A.S.L. have been supported by the Spanish projects AYA2015-65041-P and PID2019-109467GB-100 (MINECO/FEDER, UE) and Grupos Gobierno Vasco IT1366-19. Our great thanks to Omar Hila and their collaborators in Atlas Golf Marrakech Observatory for providing access to the T60cm telescope. TRAPPIST is a project funded by the Belgian Fonds (National) de la Recherche Scientifique (F.R.S.-FNRS) under grant PDR T.0120.21. TRAPPIST-North is a project funded by the University of Liège, and performed in collaboration with Cadi Ayyad University of Marrakesh. E.J. is a FNRS Senior Research Associate., Peer reviewed

Full list of authors: Morgado, B. E.; Bruno, G.; Gomes-Junior, A. R.; Pagano, I; Sicardy, B.; Fortier, A.; Desmars, J.; Maxted, P. F. L.; Braga-Ribas, F.; Queloz, D.; Sousa, S. G.; Ortiz, J. L.; Brandeker, A.; Cameron, A. Collier; Pereira, C. L.; Floren, H. G.; Hara, N.; Souami, D.; Isaak, K. G.; Olofsson, G.; Santos-Sanz, P.; Wilson, T. G.; Broughton, J.; Alibert, Y.; Alonso, R.; Anglada, G.; Barczy, T.; Barrado, D.; Barros, S. C. C.; Baumjohann, W.; Beck, M.; Beck, T.; Benz, W.; Billot, N.; Bonfils, X.; Broeg, C.; Cabrera, J.; Charnoz, S.; Csizmadia, S.; Davies, M. B.; Deleuil, M.; Delrez, L.; Demangeon, O. D. S.; Demory, B. O.; Ehrenreich, D.; Erikson, A.; Fossati, L.; Fridlund, M.; Gandolfi, D.; Gillon, M.; Gudel, M.; Heng, K.; Hoyer, S.; Kiss, L. L.; Laskar, J.; des Etangs, A. Lecavelier; Lendl, M.; Lovis, C.; Magrin, D.; Marafatto, L.; Nascimbeni, V; Ottensamer, R.; Palle, E.; Peter, G.; Piazza, D.; Piotto, G.; Pollacco, D.; Ragazzoni, R.; Rando, N.; Ratti, F.; Rauer, H.; Reimers, C.; Ribas, I; Santos, N. C.; Scandariato, G.; Segransan, D.; Simon, A. E.; Smith, A. M. S.; Steller, M.; Szabo, G. M.; Thomas, N.; Udry, S.; Van Grootel, V.; Walton, N. A.; Westerdorff, K.--This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Context. Stellar occultation is a powerful technique that allows the determination of some physical parameters of the occulting object. The result depends on the photometric accuracy, the temporal resolution, and the number of chords obtained. Space telescopes can achieve high photometric accuracy as they are not affected by atmospheric scintillation. Aims. Using ESA’s CHEOPS space telescope, we observed a stellar occultation by the transneptunian object (50000) Quaoar. We compare the obtained chord with previous occultations by this object and determine its astrometry with sub-milliarcsecond precision. Also, we determine upper limits to the presence of a global methane atmosphere on the occulting body. Methods. We predicted and observed a stellar occultation by Quaoar using the CHEOPS space telescope. We measured the occultation light curve from this dataset and determined the dis- and reappearance of the star behind the occulting body. Furthermore, a ground-based telescope in Australia was used to constrain Quaoar’s limb. Combined with results from previous works, these measurements allowed us to obtain a precise position of Quaoar at the occultation time.
Results. We present the results obtained from the first stellar occultation by a transneptunian object using a space telescope orbiting Earth; it was the occultation by Quaoar observed on 2020 June 11. We used the CHEOPS light curve to obtain a surface pressure upper limit of 85 nbar for the detection of a global methane atmosphere. Also, combining this observation with a ground-based observation, we fitted Quaoar’s limb to determine its astrometric position with an uncertainty below 1.0 mas. Conclusions. This observation is the first of its kind, and it shall be considered as a proof of concept of stellar occultation observations of transneptunian objects with space telescopes orbiting Earth. Moreover, it shows significant prospects for the James Webb Space Telescope. © B. Morgado et al. 2022, This work was carried out within the “Lucky Star” umbrella that agglomerates the efforts of the Paris, Granada and Rio teams, which is funded by the European Research Council under the European Community’s H2020 (ERC Grant Agreement No. 669416). CHEOPS is an ESA mission in partnership with Switzerland with important contributions to the payload and the ground segment from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom. The CHEOPS Consortium would like to gratefully acknowledge the support received by all the agencies, offices, universities, and industries involved. Their flexibility and willingness to explore new approaches were essential to the success of this mission. This research made use of SORA, a python package for stellar occultations reduction and analysis, developed with the support of ERC Lucky Star and LIneA/Brazil, within the collaboration of Rio-Paris-Granada teams. 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). This study was financed in part by the National Institute of Science and Technology of the e-Universe project (INCT do e-Universo, CNPq grant 465376/2014-2). The following authors acknowledge the respective (i) CNPq grants: BEM 150612/2020-6; FB-R 314772/2020-0; (ii) CAPES/Cofecub grant: BEM 394/2016-05. (iii) FAPESP grants: ARGJr 2018/11239-8; GBr, VNa, IPa, GPi, RRa, and GSc acknowledge support from CHEOPS ASI-INAF agreement n. 2019-29-HH.0. ABr was supported by the SNSA. ACC acknowledges support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. KGI is the ESA CHEOPS Project Scientist and is responsible for the ESA CHEOPS Guest Observers Programme. She does not participate in, or contribute to, the definition of the Guaranteed Time Programme of the CHEOPS mission through which observations described in this paper have been taken, nor to any aspect of target selection for the programme. ACC and TW acknowledge support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. YA and MJH acknowledge the support of the Swiss National Fund under grant 200020_172746. We acknowledge support from the Spanish Ministry of Science and Innovation and the European Regional Development Fund through grants ESP2016-80435-C2-1-R, ESP2016-80435-C2-2-R, PGC2018-098153-B-C33, PGC2018-098153-B-C31, ESP2017-87676-C5-1-R, MDM-2017-0737 Unidad de Excelencia Maria de Maeztu-Centro de Astrobiologíca (INTA-CSIC), as well as the support of the Generalitat de Catalunya/CERCA programme. The MOC activities have been supported by the ESA contract No. 4000124370. SCCB acknowledges support from FCT through FCT contracts nr. IF/01312/2014/CP1215/CT0004. XB, SC, DG, MF and JL acknowledge their role as ESA-appointed CHEOPS science team members. This project was supported by the CNES. The Belgian participation to CHEOPS has been supported by the Belgian Federal Science Policy Office (BELSPO) in the framework of the PRODEX Program, and by the University of Liège through an ARC grant for Concerted Research Actions financed by the Wallonia-Brussels Federation. LD is an F.R.S.-FNRS Postdoctoral Researcher. This work was supported by FCT – Fundação para a Ciência e a Tecnologia through national funds and by FEDER through COMPETE2020 – Programa Operacional Competitividade e Internacionalizacão by these grants: UID/FIS/04434/2019, UIDB/04434/2020, UIDP/04434/2020, PTDC/FIS-AST/32113/2017 and POCI-01-0145-FEDER- 032113, PTDC/FIS-AST/28953/2017 and POCI-01-0145-FEDER-028953, PTDC/FIS-AST/28987/2017 and POCI-01-0145-FEDER-028987, ODSD is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by national funds through FCT. PSS acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 “LEO-SBNAF” (MCIU/AEI/FEDER, UE). PSS and JLO 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), they also acknowledge the financial support by the Spanish grants AYA-2017-84637-R and PID2020-112789GB-I00, and the Proyectos de Excelencia de la Junta de Andalucía 2012-FQM1776 and PY20-01309. BOD acknowledges support from the Swiss National Science Foundation (PP00P2-190080). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (project FOUR ACES. grant agreement No 724427). It has also been carried out in the frame of the National Centre for Competence in Research PlanetS supported by the Swiss National Science Foundation (SNSF). DE acknowledges financial support from the Swiss National Science Foundation for project 200021_200726. MF and CMP gratefully acknowledge the support of the Swedish National Space Agency (DNR 65/19, 174/18). DG gratefully acknowledges financial support from the CRT foundation under Grant No. 2018.2323 “Gaseous or rocky? Unveiling the nature of small worlds”. MG is an F.R.S.-FNRS Senior Research Associate. SH gratefully acknowledges CNES funding through the grant 837319. This work was granted access to the HPC resources of MesoPSL financed by the Region Ile de France and the project Equip at Meso (reference ANR-10-EQPX-29-01) of the programme Investissements d’Avenir supervised by the Agence Nationale pour la Recherche. ML acknowledges support of the Swiss National Science Foundation under grant number PCEFP2_194576. PM acknowledges support from STFC research grant number ST/M001040/1. This work was also partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127). IRI acknowledges support from the Spanish Ministry of Science and Innovation and the European Regional Development Fund through grant PGC2018-098153-B- C33, as well as the support of the Generalitat de Catalunya/CERCA programme. SGS acknowledges support from FCT through FCT contract nr. CEECIND/00826/2018 and POPH/FSE (EC). GyMSz acknowledges the support of the Hungarian National Research, Development and Innovation Office (NKFIH) grant K-125015, a a PRODEX Experiment Agreement No. 4000137122, the Lendület LP2018-7/2021 grant of the Hungarian Academy of Science and the support of the city of Szombathely. VVG is an F.R.S-FNRS Research Associate. NAW acknowledges UKSA grant ST/R004838/1., Peer reviewed

This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Context. Stellar occultations have become one of the best techniques to gather information about the physical properties of trans-Neptunian objects (TNOs), which are critical objects for understanding the origin and evolution of our Solar System. Aims. The purpose of this work is to determine, with better accuracy, the physical characteristics of the TNO (84922) 2003 VS2 through the analysis of the multichord stellar occultation on 2019 October 22 and photometric data collected afterward. Methods. We predicted, observed, and analyzed the multichord stellar occultation of the Second Gaia Data Release (Gaia DR2) source 3449076721168026624 (mυ = 14.1 mag) by the plutino object 2003 VS2 on 2019 October 22. We performed aperture photometry on the images collected and derived the times when the star disappeared and reappeared from the observing sites that reported a positive detection. We fit the extremities of such positive chords to an ellipse using a Monte Carlo method. We also carried out photometric observations to derive the rotational light curve amplitude and rotational phase of 2003 VS2 during the stellar occultation. Combining the results and assuming a triaxial shape, we derived the 3D shape of 2003 VS2. Results. Out of the 39 observatories involved in the observational campaign, 12 sites, located in Bulgaria (one), Romania (ten), and Serbia (one), reported a positive detection; this makes it one of the best observed stellar occultations by a TNO so far. Considering the rotational phase of 2003 VS2 during the stellar occultation and the rotational light curve amplitude derived (Am = 0.264 ± 0.017 mag), we obtained a mean area-equivalent diameter of DAeq = 545 ± 13 km and a geometric albedo of 0.134 ± 0.010. By combining the rotational light curve information with the stellar occultation results, we derived the best triaxial shape for 2003 VS2, which has semiaxes a = 339 ± 5 km, b = 235 ± 6 km, and c = 226 ± 8 km. The derived aspect angle of 2003 VS2 is θ = 59° ± 2° or its supplementary θ = 121° ± 2°, depending on the north-pole position of the TNO. The spherical-volume equivalent diameter is DVeq = 524 ± 7 km. If we consider large albedo patches on its surface, the semi-major axis of the ellipsoid could be ~ 10 km smaller. These results are compatible with the previous ones determined from the single-chord 2013 and four-chord 2014 stellar occultations and with the effective diameter and albedo derived from Herschel and Spitzer data. They provide evidence that 2003 VS2’s 3D shape is not compatible with a homogeneous triaxial body in hydrostatic equilibrium, but it might be a differentiated body and/or might be sustaining some stress. No secondary features related to rings or material orbiting around 2003 VS2 were detected. © M. Vara-Lubiano et al. 2022., We acknowledge financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709). Funding from Spanish projects PID2020-112789GB-I00 from AEI and Proyecto de Excelencia de la Junta de Andalucía PY20-01309 is acknowledged. 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”). M.V-L. acknowledges funding from Spanish project AYA2017-89637-R (FEDER/MICINN). P.S-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 “LEO-SBNAF”. Part of the work of M.P. was financed by a grant of the Romanian National Authority for Scientific Research and Innovation, CNCS – UEFIS– CDI, PN-III-P1-1.1-TE-2019-1504. E.F.-V. acknowledges financial support from the Florida Space Institute and the Space Research Initiative. The following authors acknowledge the respective CNPq grants: F.B-R 309578/2017-5; B.E.M. 150612/2020-6; RV-M 304544/2017-5, 401903/2016-8; J.I.B.C. 308150/2016-3 and 305917/2019-6; M.A 427700/2018-3, 310683/2017-3 and 473002/2013-2. D.I. and O.V. acknowledge funding provided by the Ministry of Education, Science, and Technological Development of the Republic of Serbia (contracts 451-039/2021-14/200104, 451-03-9/2021-14/200002). D.I. acknowledges the support of the Alexander von Humboldt Foundation. M.H. thanks the Slovak Academy of Sciences (VEGA No. 2/0059/22) and the Slovak Research and Development Agency under the Contract No. APVV-19-0072. This work has also been supported by the VEGA grant of the Slovak Academy of Sciences No. 2/0031/18. A.P., R.S. and C.K. acknowledge the grant of K-138962 of National Research, Development and Innovation Office (Hungary). This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001 and the National Institute of Science and Technology of the e-Universe project (INCT do e-Universo, CNPq grant 465376/2014-2). 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. This research is partially based on observations collected at the Centro Astronómico Hispano-Alemán (CAHA) at Calar Alto, operated jointly by Junta de Andalucía and Consejo Superior de Investigaciones Científicas (IAA-CSIC). This research is also partially based on observations carried out at the Observatorio de Sierra Nevada (OSN) operated by Instituto de Astrofísica de Andalucía (CSIC). This article is also based on observations made in the Observatorios de Canarias del IAC with the Liverpool Telescope operated on the island of La Palma by the Instituto de Astrofísica de Canarias in the Roque de los Muchachos Observatory., Peer reviewed

Full list of authors: Morgado, B. E.; Sicardy, B.; Braga-Ribas, F.; Ortiz, J. L.; Salo, H.; Vachier, F.; Desmars, J.; Pereira, C. L.; Santos-Sanz, P.; Sfair, R.; de Santana, T.; Assafin, M.; Vieira-Martins, R.; Gomes-Junior, A. R.; Margoti, G.; Dhillon, V. S.; Fernandez-Valenzuela, E.; Broughton, J.; Bradshaw, J.; Langersek, R.; Benedetti-Rossi, G.; Souami, D.; Holler, B. J.; Kretlow, M.; Boufleur, R. C.; Camargo, J. I. B.; Duffard, R.; Beisker, W.; Morales, N.; Lecacheux, J.; Rommel, F. L.; Herald, D.; Benz, W.; Jehin, E.; Jankowsky, F.; Marsh, T. R.; Littlefair, S. P.; Bruno, G.; Pagano, I.; Brandeker, A.; Collier-Cameron, A.; Floren, H. G.; Hara, N.; Olofsson, G.; Wilson, T. G.; Benkhaldoun, Z.; Busuttil, R.; Burdanov, A.; Ferrais, M.; Gault, D.; Gillon, M.; Hanna, W.; Kerr, S.; Kolb, U.; Nosworthy, P.; Sebastian, D.; Snodgrass, C.; Teng, J. P.; de Wit, J., Planetary rings are observed not only around giant planets1, but also around small bodies such as the Centaur Chariklo2 and the dwarf planet Haumea3. Up to now, all known dense rings were located close enough to their parent bodies, being inside the Roche limit, where tidal forces prevent material with reasonable densities from aggregating into a satellite. Here we report observations of an inhomogeneous ring around the trans-Neptunian body (50000) Quaoar. This trans-Neptunian object has an estimated radius4 of 555 km and possesses a roughly 80-km satellite5 (Weywot) that orbits at 24 Quaoar radii6,7. The detected ring orbits at 7.4 radii from the central body, which is well outside Quaoar’s classical Roche limit, thus indicating that this limit does not always determine where ring material can survive. Our local collisional simulations show that elastic collisions, based on laboratory experiments8, can maintain a ring far away from the body. Moreover, Quaoar’s ring orbits close to the 1/3 spin–orbit resonance9 with Quaoar, a property shared by Chariklo’s2,10,11 and Haumea’s3 rings, suggesting that this resonance plays a key role in ring confinement for small bodies. © 2023, The Author(s), under exclusive licence to Springer Nature Limited., This work was carried out under the Lucky Star umbrella that agglomerates the efforts of the Paris, Granada and Rio teams, which is funded by the ERC under the European Community’s H2020 (ERC grant agreement no. 669416). Part of the results were obtained using CHEOPS data. CHEOPS is an ESA mission in partnership with Switzerland with important contributions to the payload and the ground segment from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden and the UK. The CHEOPS Consortium gratefully acknowledge the support received by all the agencies, offices, universities and industries involved. Their flexibility and willingness to explore new approaches were essential to the success of this mission. The design and construction of HiPERCAM was supported by the ERC under the European Union’s Seventh Framework Programme (FP/2007-2013) under ERC-2013-ADG grant agreement no. 340040 (HiPERCAM). HiPERCAM operations and V.S.D. are funded by the Science and Technology Facilities Council (grant no. ST/V000853/1). The GTC is installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, on the island of La Palma. This work has made use of data from the 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). This study was financed in part by the National Institute of Science and Technology of the e-Universe project (INCT do e-Universo, CNPq grant no. 465376/2014-2). This study was financed in part by CAPES - Finance Code 001. The following authors acknowledge the respective (1) CNPq grants to B.E.M. no. 150612/2020-6; F.B.-R. no. 314772/2020-0; R.V.-M. no. 307368/2021-1; M.A. nos. 427700/2018-3, 310683/2017-3 and 473002/2013-2; and J.I.B.C. nos. 308150/2016-3 and 305917/2019-6. (2) CAPES/Cofecub grant to B.E.M. no. 394/2016-05. (3) FAPERJ grant no. M.A. E-26/111.488/2013. (4) FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) grants to A.R.G.-J. no. 2018/11239-8 and R.S. no. 2016/24561-0. (5) CAPES-PrInt Program grant to G.B.-R. no. 88887.310463/2018-00, mobility number 88887.571156/2020-00. (6) DFG (the German Research Foundation) grant to R.S. no. 446102036. P.S-S. and R.D. acknowledge financial support by the Spanish grant no. AYA-RTI2018-098657-J-I00 ‘LEO-SBNAF’ (MCIU/AEI/FEDER, UE). J.L.O., P.S-S., R.D. and N.M. 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 (grant no. SEV-2017-0709), and they also acknowledge the financial support by the Spanish grant nos. AYA-2017-84637-R and PID2020-112789GB-I00, and the Proyectos de Excelencia de la Junta de Andalucía grant nos. 2012-FQM1776 and PY20-01309. G.B-R. and I.P. acknowledge support from CHEOPS ASI-INAF agreement no. 2019-29-HH.0. A.B. was supported by the SNSA. A.C.-C. and T.G.W. acknowledge support from STFC consolidated grant nos. ST/R000824/1 and ST/V000861/1, and UK Space Agency grant no. ST/R003203/1. U.K. and R.B. acknowledge support by The OpenSTEM Laboratories, an initiative funded by the Higher Education Funding Council for England and the Wolfson Foundation. J.W. gratefully acknowledges financial support from the Heising-Simons Foundation, C. Masson and P. A. Gilman for Artemis, the first telescope of the SPECULOOS network situated in Tenerife, Spain. The ULiege’s contribution to SPECULOOS has received funding from the ERC under the European Union’s Seventh Framework Programme (FP/2007-2013) (grant agreement no. 336480/SPECULOOS), from the Balzan Prize and Francqui Foundations, from the Belgian Scientific Research Foundation (F.R.S.-FNRS; grant no. T.0109.20), from the University of Liege and from the ARC grant for Concerted Research Actions financed by the Wallonia-Brussels Federation. TRAPPIST is a project funded by the Belgian Fonds (National) de la Recherche Scientique (F.R.S.-FNRS) under grant no. PDR T.0120.21. TRAPPIST-North is a project funded by the University of Liege, in collaboration with the Cadi Ayyad University of Marrakech (Morocco). E.J. is FNRS Senior Research Associate., With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S)., Peer reviewed

Full list of authors: Fernández-Valenzuela, E.; Morales, N.; Vara-Lubiano, M.; Ortiz, J. L.; Benedetti-Rossi, G.; Sicardy, B.; Kretlow, M.; Santos-Sanz, P.; Morgado, B.; Souami, D.; Organero, F.; Ana, L.; Fonseca, F.; Román, A.; Alonso, S.; Gonçalves, R.; Ferreira, M.; Iglesias-Marzoa, R.; Lamadrid, J. L.; Alvarez-Candal, A.; Assafin, M.; Braga-Ribas, F.; Camargo, J. I. B.; Colas, F.; Desmars, J.; Duffard, R.; Lecacheux, J.; Gomes-Júnior, A. R.; Rommel, F. L.; Vieira-Martins, R.; Pereira, C. L.; Casanova, V.; Selva, A.; Perelló, C.; Mottola, S.; Hellmich, S.; Maestre, J. L.; Castro-Tirado, A. J.; Pal, A.; Trigo-Rodriguez, J. M.; Beisker, W.; Laporta, A.; Garcés, M.; Escaned, L.; Bretton, M.-- This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Within our program of physical characterization of trans-Neptunian objects and centaurs, we predicted a stellar occultation by the centaur (54598) Bienor to occur on January 11, 2019, with good observability potential. We obtained high accuracy astrometric data to refine the prediction, resulting in a shadow path favorable for the Iberian Peninsula. This encouraged us to carry out an occultation observation campaign that resulted in five positive detections from four observing sites. This is the fourth centaur for which a multichord (more than two chords) stellar occultation has been observed so far, the other three being (2060) Chiron, (10199) Chariklo, and (95626) 2002 GZ32. From the analysis of the occultation chords, combined with the rotational light curve obtained shortly after the occultation, we determined that Bienor has an area-equivalent diameter of 150 ± 20 km. This diameter is ~30 km smaller than the one obtained from thermal measurements. The position angle of the short axis of the best fitting ellipse obtained through the analysis of the stellar occultation does not match that of the spin axis derived from long-term photometric models. We also detected a strong irregularity in one of the minima of the rotational light curve that is present no matter the aspect angle at which the observations were done. We present different scenarios to reconcile the results from the different techniques. We did not detect secondary drops related to potential rings or satellites. Nonetheless, similar rings in size to that of Chariklo's cannot be discarded due to low data accuracy., The work leading to these results has received funding from the European Research Council under the European Community’s H2020 2014-2021 ERC Grant Agreement no. 669416 “Lucky Star”. E.F.-V. acknowledges financial support by the Space Research Initiative from State of Florida. P.S.-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 “LEO-SBNAF” (MCIU/AEI/FEDER, UE). A.P. acknowledges financial support of the Hungarian National Research, Development and Innovation Office (NKFIH) Grant K-138962. G.B.-R. acknowledges CAPES-PRINT/UNESP Process 88887.310463/2018-00, Project 88887.571156/2020-00. M.A. acknowledges financial support from CNPq grants with numbers 427700/2018-3,310683/2017-3,473002/2013-2, and FAPERJ grant no. E-26/111.488/2013. F.B.-R. acknowledges financial support from CNPq grant n° 314772/2020-0. J.I.B.C. acknowledges financial support from CNPq grants with numbers 308150/2016-3 and 305917/2019-6. R.V.-M. acknowledges financial support from CNPq grants with numbers 304544/2017-5, and 401903/2016-8. B.M. acknowledges financial support from CNPq grant no. 150612/2020-6. A.R.-G.-J. acknowledges financial support from FAPESP grant no. 2018/11239-8. J.M.T.-R. research was supported by the research Grant No. PGC2018-097374-B-I00, which is funded by FEDER/Ministerio de Ciencia e Innovación, Agencia Estatal de Investigación. This study was partly financed by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001 and the National Institute of Science and Technology of the e-Universe project (INCT do e-Universo, CNPq grant 465376/2014-2). We acknowledge financial support by the Spanish grant AYA-2017-84637-R, and the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709)”. This research has been partially funded by the Junta de Andalucía PY20_01309 and Agencia Estatal de Investigatión PID2020-112789GB-I00 projects. This research is partially based on observations collected at the Centro Astronómico Hispano-Alemán (CAHA) at Calar Alto, operated jointly by Junta de Andalucía and Consejo Superior de Investigaciones Científicas (IAA-CSIC). This research is partially based on observation carried out at the Observatorio de Sierra Nevada (OSN) operated by Instituto de Astrofísica de Andalucía (CSIC) and the Excalibur telescope at the Observatorio Astrofísico de Javalambre in Teruel, a Spanish Infraestructura Cientifico-Técnica Singular (ICTS) owned, managed and operated by the Centro de Estudios de Física del Cosmos de Aragón (CEFCA). Excalibur is funded with the Fondos de Inversiones de Teruel (FITE). This worked was partially carried out with observations from the Joan Oró Telescope (TJO) of the Montsec Observatory (OdM), which is owned by the Catalan Government and operated by the Institute for Space Studies of Catalonia (IEEC)., With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S)., Peer reviewed

This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., The rotational states of the members in the dwarf planet-satellite systems in the trans-Neptunian region are determined by formation conditions and the tidal interaction between the components. These rotational characteristics serve as prime tracers of their evolution. A number of authors have claimed a very broad range of values for the rotation period for the dwarf planet Eris, ranging from a few hours to a rotation that is (nearly) synchronous with the orbital period (15.8 d) of its satellite, Dysnomia. In this Letter, we present new light curve data for Eris, taken with ∼1–2 m-class ground based telescopes and with the TESS and Gaia space telescopes. The TESS data did not provide a well-defined light curve period, but it could be used to constrain light curve variations to a maximum possible light curve amplitude of Δm ≤ 0.03 mag (1-σ) for P ≤ 24 h periods. Both the combined ground-based data and Gaia measurements unambiguously point to a light curve period equal to the orbital period of Dysnomia, P = 15.8 d, with a light curve amplitude of Δm ≈ 0.03 mag, indicating that the rotation of Eris is tidally locked. Assuming that Dysnomia has a collisional origin, calculations with a simple tidal evolution model show that Dysnomia must be relatively massive (mass ratio of q = 0.01–0.03) and large (radius of Rs ≥ 300 km) to have the potential to slow Eris down to a synchronised rotation. These simulations also indicate that (assuming tidal parameters usually considered for trans-Neptunian objects) the density of Dysnomia should be 1.8–2.4 g cm−3. This is an exceptionally high value among similarly sized trans-Neptunian objects, setting important constraints on their formation conditions. © The Authors 2023., The research leading to these results has received funding from the K-138962 grant of the National Research, Development and Innovation Office (NKFIH, Hungary). The data presented in this Letter were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts. This research has made use of data and services provided by the International Astronomical Union’s Minor Planet Center. Part of the funding for GROND (both hardware as well as personnel) was generously granted from the Leibniz-Prize to Prof. G. Hasinger (DFG grant HA 1850/28-1). We are grateful to the CAHA and OSN staff. This research is partially based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by Junta de Andalucía and Consejo Superior de Investigaciones Científicas (IAA-CSIC). This research was also partially based on observation carried out at the Observatorio de Sierra Nevada (OSN) operated by Instituto de Astrofísica de Andalucía (CSIC). P.S-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 “LEO-SBNAF”(MCIU/AEI/FEDER, UE). P.S-S., J.L.O., N.M., and R.D. 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), they also acknowledge the financial support by the Spanish grants AYA-2017-84637-R and PID2020-112789GB-I00, and the Proyectos de Excelencia de la Junta de Andalucía 2012-FQM1776 and PY20-01309. This work made use of Astropy: (http://www.astropy.org) a community-developed core Python package and an ecosystem of tools and resources for astronomy (Astropy Collaboration 2013, 2018, 2022). 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., With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S)., Peer reviewed

This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/., The goal of Project GAUSS (Genesis of Asteroids and evolUtion of the Solar System) is to return samples from the dwarf planet Ceres. Ceres is the most accessible candidate of ocean worlds and the largest reservoir of water in the inner Solar System. It shows active volcanism and hydrothermal activities in recent history. Recent evidence for the existence of a subsurface ocean on Ceres and the complex geochemistry suggest past habitability and even the potential for ongoing habitability. GAUSS will return samples from Ceres with the aim of answering the following top-level scientific questions:What is the origin of Ceres and what does this imply for the origin of water and other volatiles in the inner Solar System?What are the physical properties and internal structure of Ceres? What do they tell us about the evolutionary and aqueous alteration history of dwarf planets?What are the astrobiological implications of Ceres? Is it still habitable today?What are the mineralogical connections between Ceres and our current collections of carbonaceous meteorites? © 2023 Elsevier B.V., All rights reserved., The early concept of the white paper has benefitted from various discussions with Professor Adam Showman, who sadly passed away in March 2020. His contribution and influence are gratefully acknowledged and sorely missed. Part of this work has been carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). J.-Y.L. acknowledges partial support from the Solar System Exploration Research Virtual Institute 2016 (SSERVI16) Cooperative Agreement (grant NNH16ZDA001N), SSERVI-TREX to the Planetary Science Institute. J.A. acknowledges support from the European Research Council Starting Grant 757390 (CAstRA). A.J.C. and G.H.J. acknowledge support from the STFC consolidated grant to UCL-MSSL STS0002401. P. Santos-Sanz, and R. Duffard acknowledges financial support by the Spanish grant AYA- RTI2018-098657-J-I00 ’LEO-SBNAF’ (MCIU/AEI/FEDER, UE). J.L. Ortiz, P. Santos-Sanz, and R. Duffard 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). J.M.T-R. acknowledges support from the Spanish Ministry of Science and Innovation (project PGC2018-097374-B-I00). J.M.T-R.’s research has been funded by the research project (PGC2018-097374-B-I00), funded by FEDER/Ministerio de Ciencia e Innovación – Agencia Estatal de Investigación. Open Access funding enabled and organized by Projekt DEAL., Peer reviewed