Astrometry and Light Curves of Asteroids with the SUBARU Telecope

Program available at: http://www.imcce.fr/hosted_sites/naroo/program.htmlInternational audienceWe present the reductions of observations of a single ecliptic field, carried out over one night in September 2, 2002, at the focus of the SUBARU 8.2 m telescope. The frames necessary for the reduction were retrieved through the database SMOKA (Subaru Mitaka Okayama Kiso Archive System) High frequency multi shots imaging of the fields enable to detect sub-kilometric asteroids and to perform astrometric and photometric reduction, leading in some cases to the extraction of light curves

The stellar occultations by the largest satellite of the dwarf planet Haumea, Hi'iaka

Two stellar occultations by the largest satellite of the dwarf planet Haumea, Hi'iaka, were predicted to happen on April, 6th and 16th, 2021. Additional high accuracy astrometric analysis was carried out in order to refine the prediction for April 6th, using several telescopes in the 1.2-m to 2-m range, with the final shadow path crossing North Africa. We successfully detected the first event from TRAPPIST-North telescope at Oukaïmeden Observatory (Morocco). Although it was recorded from only one site, this first detection allowed us to improve the prediction for the second that crossed North America from East to West. We had a good success recording six positive detections and several negative detections that constrain the shape and size of the body. The light curves obtained from the different observatories provide the time at which the star disappears and reappears, which are translated into chords (the projected lines on the sky-plane as observed from each location). Additionally, we carried out a campaign to study Hi'iaka's rotational light-curve, studying the residuals of Haumea's rotational light-curve to a four-order Fourier fit. We obtained the rotational phases at the times of the occultations, which is critical for the analysis of the occultations, given that Hi'iaka is clearly non-spherical. Our preliminary results show that Hi'iaka indeed has a triaxial shape with a larger effective diameter than what has been published so far. The preliminary results and their implications will be discussed in this talk

The multi-chord stellar occultation by (19521) Chaos on 2020 November 20

Physical properties of Trans-Neptunian Objects (TNOs) have been of increasing interest in the last two decades, as these objects are considered to be among the least altered through the Solar System evolution, and thus preserve valuable information about its origin [1]. The study of these objects through the ground-based method of stellar occultations has risen in the last years, as this technique allows the determination of physical properties with considerably good accuracies [2,3,4]. Here we present the results of the multi-chord stellar occultation of the GAIA source 3444789965847631104 (mv≍16.8) by the TNO (19521) Chaos on 2020 November 20, which was predicted within our systematic programme on stellar occultations by TNOs and outer solar system bodies [5]. The prediction was updated with astrometric observations carried out two days before the event with the 1.23-m telescope at Calar Alto observatory in Almería, Spain, and it was favorable to the South of Europe. The campaign that we organized involved 19 observing sites and resulted in three positive detections, one of them obtained from the 4.2-m WHT telescope at La Palma, 11 negative detections, and 5 sites that could not observe due to bad weather. We derived the instantaneous limb of Chaos by fitting the extremities of the positive chords to an ellipse to determine accurate size, shape, and geometric albedo for this object. The preliminary results give a slightly smaller area-equivalent diameter than the one derived from Herschel thermal data [6], but photometric observations of this object are still under analysis to complement and improve the results. References[1] Morbidelli, A., Levison, H. F., & Gomes, R. 2008, ed. M. A. Barucci, H. Boehnhardt, D. P. Cruikshank, A. Morbidelli, R. Dotson, 275[2] Ortiz, J. L., Sicardy, B., Braga-Ribas, F., et al. 2012, Nature, 491, 566[3] Braga-Ribas, F., Sicardy, B., Ortiz, J. L., et al. 2013, ApJ, 773, 26[4] Ortiz, J.L., Santos-Sanz, P., Sicardy, B., et al. 2017, Nature, 550, 7675, pp. 219-223[5] Camargo, J. I. B., Vieira-Martins, R., Assafin, M., et al. 2014, A&A, 561, A37[6] Vilenius, E., Kiss, C., Mommert, M., Müller, T., et al. 2012, A&A, 541, A94 Acknowledgements 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). 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'' (MCIU/AEI/FEDER, UE). 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). We are grateful to the CAHA and OSN staffs. 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). Partially based on observations made with the Tx40 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). Tx40 is funded with the Fondos de Inversiones de Teruel (FITE)

After DART: Using the First Full-scale Test of a Kinetic Impactor to Inform a Future Planetary Defense Mission

NASA’s Double Asteroid Redirection Test (DART) is the first full-scale test of an asteroid deflection technology. Results from the hypervelocity kinetic impact and Earth-based observations, coupled with LICIACube and the later Hera mission, will result in measurement of the momentum transfer efficiency accurate to ∼10% and characterization of the Didymos binary system. But DART is a single experiment; how could these results be used in a future planetary defense necessity involving a different asteroid? We examine what aspects of Dimorphos’s response to kinetic impact will be constrained by DART results; how these constraints will help refine knowledge of the physical properties of asteroidal materials and predictive power of impact simulations; what information about a potential Earth impactor could be acquired before a deflection effort; and how design of a deflection mission should be informed by this understanding. We generalize the momentum enhancement factor β, showing that a particular direction-specific β will be directly determined by the DART results, and that a related direction-specific β is a figure of merit for a kinetic impact mission. The DART β determination constrains the ejecta momentum vector, which, with hydrodynamic simulations, constrains the physical properties of Dimorphos’s near-surface. In a hypothetical planetary defense exigency, extrapolating these constraints to a newly discovered asteroid will require Earth-based observations and benefit from in situ reconnaissance. We show representative predictions for momentum transfer based on different levels of reconnaissance and discuss strategic targeting to optimize the deflection and reduce the risk of a counterproductive deflection in the wrong direction

A portrait of the Trans-Neptunian Object (143707) 2003 UY117 from a stellar occultation and photometry data.

Within the Lucky Star international collaboration* on stellar occultations by TNOs and other outer solar system bodies, we predicted the occultation by the TNO (143707) 2003 UY117 of an mV ~ 14.6 mag star on 23 October 2020. Around a week before the occultation date, we updated and refined the prediction using high precision astrometry obtained using the 2 m Liverpool telescope located at El Roque de Los Muchachos Observatory on La Palma, Spain. The update resulted in a shadow path with good observability potential. We carried out a specific campaign involving 27 observing sites in the south of Spain and North of Africa to observe the occultation. We recorded 4 positive detections and several very close misses to the south of the body. With this information we determined the silhouette of 2003 UY117 at the moment of the occultation. We also obtained the geometric albedo and the size for this object. In addition to this, we carried out several photometric runs with large telescopes to determine the rotation period and rotational phase at the time of the occultation. The body presents a clear double-peaked rotational light curve consistent with a triaxial ellipsoid of considerable elongation, which means that a rotational light curve analysis is critical to correctly interpret the occultation results. The preliminary analysis indicates a larger equivalent diameter than that determined from Herschel thermal data, although consistent within the large error bars of the thermal determination. We will present the preliminary results and discuss their implications.*Lucky Star (LS) is an EU-funded research activity to obtain physical properties of distant Solar System objects using stellar occultations. LS collaboration agglomerates the efforts of the Paris, Granada, and Rio teams. https://lesia.obspm.fr/lucky-star/ Acknowledgements:JLO, PS-S, NM, MV, 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 Astrofísica de Andalucía (SEV-2017-0709), they also acknowledge the financial support by the Spanish grant AYA-2017-84637-R and AYARTI2018- 098657-J-I00 `LEO-SBNAF' (MCIU/AEI/FEDER, UE)

After DART: Using the first full-scale test of a kinetic impactor to inform a future planetary defense mission

NASA's Double Asteroid Redirection Test (DART) is the first full-scale test of an asteroid deflection technology. Results from the hypervelocity kinetic impact and Earth-based observations, coupled with LICIACube and the later Hera mission, will result in measurement of the momentum transfer efficiency accurate to ~10% and characterization of the Didymos binary system. But DART is a single experiment; how could these results be used in a future planetary defense necessity involving a different asteroid? We examine what aspects of Dimorphos's response to kinetic impact will be constrained by DART results; how these constraints will help refine knowledge of the physical properties of asteroidal materials and predictive power of impact simulations; what information about a potential Earth impactor could be acquired before a deflection effort; and how design of a deflection mission should be informed by this understanding. We generalize the momentum enhancement factor $\beta$, showing that a particular direction-specific $\beta$ will be directly determined by the DART results, and that a related direction-specific $\beta$ is a figure of merit for a kinetic impact mission. The DART $\beta$ determination constrains the ejecta momentum vector, which, with hydrodynamic simulations, constrains the physical properties of Dimorphos's near-surface. In a hypothetical planetary defense exigency, extrapolating these constraints to a newly discovered asteroid will require Earth-based observations and benefit from in-situ reconnaissance. We show representative predictions for momentum transfer based on different levels of reconnaissance and discuss strategic targeting to optimize the deflection and reduce the risk of a counterproductive deflection in the wrong direction

After DART: Using the First Full-scale Test of a Kinetic Impactor to Inform a Future Planetary Defense Mission

After DART: Using the First Full-scale Test of a Kinetic Impactor to Inform a Future Planetary Defense Mission Thomas S. Statler 1 , Sabina D. Raducan 2 , Olivier S. Barnouin 3 , Mallory E. DeCoster 3 , Steven R. Chesley 4 , Brent Barbee 5 , Harrison F. Agrusa 6 , Saverio Cambioni 7 , Andrew F. Cheng 3 , Elisabetta Dotto 8 , Siegfried Eggl9 , Eugene G. Fahnestock 4 , Fabio Ferrari 2 , Dawn Graninger 3 , Alain Herique 10 , Isabel Herreros 11 , Masatoshi Hirabayashi 12,13 , Stavro Ivanovski 14 , Martin Jutzi 2 , Özgür Karatekin 15 , Alice Lucchetti 16 , Robert Luther 17 , Rahil Makadia 9 , Francesco Marzari 18 , Patrick Michel 19 , Naomi Murdoch 20 , Ryota Nakano13 , Jens Ormö 11 , Maurizio Pajola 16 , Andrew S. Rivkin3 , Alessandro Rossi 21 , Paul Sánchez 22 , Stephen R. Schwartz 23 , Stefania Soldini 24 , Damya Souami 19 , Angela Stickle 3 , Paolo Tortora 25 , Josep M. Trigo-Rodríguez 26,27 , Flaviane Venditti 28 , Jean-Baptiste Vincent 29 , and Kai Wünnemann 17,30 1 Planetary Defense Coordination Office and Planetary Science Division, NASA Headquarters, 300 Hidden Figures Way SW, Washington, DC 20546, USA [email protected] 2 Space Research and Planetary Sciences, Physics Institute, University of Bern, Bern, 3012, Switzerland 3 Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA 4 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA 5 NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 6 Department of Astronomy, University of Maryland, College Park, MD 20742, USA 7 Department of Earth, Atmospheric & Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA 8 INAF-Osservatorio Astronomico di Roma, Rome, I-00078, Italy 9 Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA 10 Univ. Grenoble Alpes, CNRS, CNES, IPAG, F-38000 Grenoble, France 11 Centro de Astrobiología CSIC-INTA, Instituto Nacional de Técnica Aeroespacial, E-28850 Torrejón de Ardoz, Spain 12 Department of Geosciences, Auburn University, Auburn, AL 36849, USA 13 Department of Aerospace Engineering, Auburn University, Auburn, AL 36849, USA 14 INAF- Osservatorio Astronomico di Trieste, Trieste I-34143, Italy 15 Royal Observatory of Belgium, Belgium 16 INAF-Astronomical Observatory of Padova, Padova I-35122, Italy 17 Museum für Naturkunde—Leibniz Institute for Evolution and Biodiversity Science, Germany 18 University of Padova, Padova, Italy 19 Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Nice F-06304, France 20 Institut Supérieur de l’Aéronautique et de l’Espace (ISAE-SUPAERO), Université de Toulouse, Toulouse, France 21 IFAC-CNR, Sesto Fiorentino I-50019, Italy 22 Colorado Center for Astrodynamics Research, University of Colorado Boulder, Boulder, CO 80303, USA 23 Planetary Science Institute, Tucson, AZ 85719, USA 24 Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, UK 25 Alma Mater Studiorum—Università di Bologna, Department of Industrial Engineering, Interdepartmental Center for Industrial Research in Aerospace, Via Fontanelle 40—Forlì (FC)—I-47121, Italy 26 Institute of Space Sciences (ICE, CSIC), Cerdanyola del Vallès, E-08193 Barcelona, Catalonia, Spain 27 Institut d’Estudis Espacials de Catalunya (IEEC), Ed. Nexus, E-08034 Barcelona, Catalonia, Spain 28 Arecibo Observatory, University of Central Florida, HC-3 Box 53995, Arecibo, PR 00612, USA 29 German Aerospace Center, DLR Berlin, Germany 30 Freie Universität Berlin, Germany Received 2022 August 9; revised 2022 September 18; accepted 2022 September 22; published 2022 October 28 Abstract NASA’s Double Asteroid Redirection Test (DART) is the first full-scale test of an asteroid deflection technology. Results from the hypervelocity kinetic impact and Earth-based observations, coupled with LICIACube and the later Hera mission, will result in measurement of the momentum transfer efficiency accurate to ∼10% and characterization of the Didymos binary system. But DART is a single experiment; how could these results be used in a future planetary defense necessity involving a different asteroid? We examine what aspects of Dimorphos’s response to kinetic impact will be constrained by DART results; how these constraints will help refine knowledge of the physical properties of asteroidal materials and predictive power of impact simulations; what information about a potential Earth impactor could be acquired before a deflection effort; and how design of a deflection mission should be informed by this understanding. We generalize the momentum enhancement factor β, showing that a particular direction-specific β will be directly determined by the DART results, and that a related direction- specific β is a figure of merit for a kinetic impact mission. The DART β determination constrains the ejecta momentum vector, which, with hydrodynamic simulations, constrains the physical properties of Dimorphos’s near- surface. In a hypothetical planetary defense exigency, extrapolating these constraints to a newly discovered asteroid will require Earth-based observations and benefit from in situ reconnaissance. We show representative predictions for momentum transfer based on different levels of reconnaissance and discuss strategic targeting to optimize the deflection and reduce the risk of a counterproductive deflection in the wrong direction

Physical properties of the trans-Neptunian binary 2000 YW₁₃₄

The study of trans-Neptunian binaries (TNBs) remains one of the most active areas of progress in understanding the solar system beyond Neptune. TNBs have been found in every dynamical population of the trans-Neptunian region (Noll et al. 2020), with proportions ranging from 29 % in the cold classical population to 5.5 % for the remaining classes combined (Brunini 2020). The formation of the contact TNB Arrokoth is one of the challenges that formation models face nowadays. The current angular momentum of Arrokoth is too low and the current binary formation scenarios, by either rotational fission or streaming instability (Nesvorný et al. 2019), require also loss of angular momentum (McKinnon et al. 2020). Additionally, formation mechanisms of close binaries may be distinct from those for the wider pairs. As the angular momentum of a system approaches that of an object spinning near its critical rotation period, rotational fission is the most likely explanation for their formation (Descamps et al. 2008), which is thought to be the case for the proposed satellites of Varuna and 2002 TC302 systems (Fernández-Valenzuela et al. 2019; Ortiz et al. 2020). If close TNBs turn out to be common for objects rotating close to the breakup limit, that could reveal important clues about angular momentum evolution during accretion for TNOs (Petit et al. 2011). However, characterizing binary systems at such distances is challenging. From the ~120 known TNBs, only around 40 have their mutual orbit fully determined, let alone physical characterization. 2000 YW134 is a TNB in a 3:8 resonance with an orbital semi-major axis of 57.4 au (a rare occurrence). On February 23rd, 2022, it occulted the Gaia EDR3 star 627356458358636544 (V = 17.1 mag). The stellar occultation was initially predicted using the JPL orbit solution #24, and updated using data from the 1.5-m and 1.23-m telescopes at Sierra Nevada and Calar Alto Observatories, using the same methodology as explained in Ortiz et al (2020). From the 17 observatories involved, seven reported positive chords, with five of them corresponding to the main body and the other two chords corresponding to its satellite. We are currently working on the analysis of these data in order to obtain the physical properties that characterize the system. Preliminary results show that the lower limit for the equivalent projected diameter of the satellite is twice the previously estimated size from HST observations (Stephens et al. 2006). We will also compare our results with the area-equivalent diameter and albedo obtained using thermal data from Herschel and Spitzer observations (Farkas-Takács et al. 2020)

Achievement of the planetary defense investigations of the Double Asteroid Redirection Test (DART) mission

NASA's Double Asteroid Redirection Test (DART) mission was the first to demonstrate asteroid deflection, and the mission's Level 1 requirements guided its planetary defense investigations. Here, we summarize DART's achievement of those requirements. On 2022 September 26, the DART spacecraft impacted Dimorphos, the secondary member of the Didymos near-Earth asteroid binary system, demonstrating an autonomously navigated kinetic impact into an asteroid with limited prior knowledge for planetary defense. Months of subsequent Earth-based observations showed that the binary orbital period was changed by –33.24 minutes, with two independent analysis methods each reporting a 1σ uncertainty of 1.4 s. Dynamical models determined that the momentum enhancement factor, β, resulting from DART's kinetic impact test is between 2.4 and 4.9, depending on the mass of Dimorphos, which remains the largest source of uncertainty. Over five dozen telescopes across the globe and in space, along with the Light Italian CubeSat for Imaging of Asteroids, have contributed to DART's investigations. These combined investigations have addressed topics related to the ejecta, dynamics, impact event, and properties of both asteroids in the binary system. A year following DART's successful impact into Dimorphos, the mission has achieved its planetary defense requirements, although work to further understand DART's kinetic impact test and the Didymos system will continue. In particular, ESA's Hera mission is planned to perform extensive measurements in 2027 during its rendezvous with the Didymos–Dimorphos system, building on DART to advance our knowledge and continue the ongoing international collaboration for planetary defense

Etude dynamique et observationnelle des astéroïdes de la ceinture principale

Asteroids are regarded as the vestiges of our primitive solar system. The discovery of the first one 210 years ago has profoundly changed our perception of the universe. In this thesis, I investigate both dynamical and observational aspects of the Main Belt asteroid population. The introduction is devoted to the discovery of the first asteroid and the consequences that followed as well as explaining the importance of studying them. In discussing the topic of the dynamics of asteroids, I study the most appropriate reference plane, which was introduced by Laplace over two centuries ago as "the invariable". I discuss its characterisation, as well as the effect of the three largest minor-bodies, and the contribution of the planets upon its orientation. In the dynamical part I study the Main Belt Asteroid, as they are regarded as natural laboratories, where one can test theories and dynamical models. The first study focuses on examining the distributions of these populations in regards to osculatory orbital planes. In the second one I am interested in the study of dynamical families of asteroids, i.e. the remnants of a parent body after its break-up. In particular, I study the long-term evolution of the members of the Vesta family. By use of a Gauss-Radau integrator, I evaluate the diffusion of the Vesta family. The gravitational effects of all planets and the largest minor bodies, relativistic and non-gravitational Yarkowsky effects are included in the dynamics. Finally in the observational part, I dive into the reduction and analysis of observational data that was acquired by the 8.2m SUBARU telescope, within the framework of the SMBAS-III (Sub-km Main Belt Asteroid Survey). I present the two methods used for object detection: the classical, naked eye method and an automated one, and apply both of them to the data. Once the objects detected, I proceed to astrometric and photometric analysis, taxonomic classification as well as establishing light curves and periods of rotation. In conclusion, I demonstrate how this thesis has allowed me to explore different aspects of the Main Belt Asteroids.Les astéroïdes sont les vestiges de notre système solaire primitif. Inconnus il y a encore 210 ans, leur découverte a changé notre vision du monde. Je me suis proposée dans cette thèse d'étudier les aspects tant dynamiques qu'observationnels relatifs à ces objets. Je prends le temps d'aborder le contexte historique de leur découverte ainsi que les conséquences qui y font suite. Ceci m'amène à définir le plan de référence le mieux adapté à leur étude. Laplace, il y a deux siècles de cela, s'était également intéressé à ce plan pour l'étude des planètes. Mon travail porte sur la caractérisation de ce plan, dit "invariable", mais aussi sur l'évaluation de l'effet des "plus gros petits corps" du système solaire et à la contribution de chaque planète sur son orientation. Dans la partie dynamique, je me cantonne à l'étude des astéroïdes de la ceinture principale. Je me penche sur les différentes distributions de ces populations, aujourd'hui considérées comme laboratoires grandeur nature permettant de tester théories et modèles dynamiques. Je m'intéresse à la distribution de ces populations en terme de plans orbitaux. Je m'intéresse à un autre type de distribution que sont les familles d'astéroïdes, i.e astéroïdes provenant d'un même corps parent. En particulier, j'étudie la dynamique à long terme des membres de la famille de l'astéroïde (4) Vesta. J'inclue à cet égard les effets relativistes ainsi que l'effet Yarkowsky, par essence non gravitationnel. Enfin dans la partie observationnelle, je m'intéresse à deux méthodes de détections des astéroïdes, l'une à l'oeil nu, l'autre automatisée. Enfin, je les applique aux données, du télescope SUBARU de 8,2m, dans le cadre du programme SMBAS-III (Sub-km Main Belt Asteroid Survey). En conclusion, je montre comment cette thèse m'a permis d'aborder sous différents aspects la population des astéroïdes