Astronomy & Astrophysics manuscript no. models_2015 c ESO 2016 August 7, 2016 New and updated convex shape models of asteroids based on optical data from a large collaboration network J. Hanuš1,2∗, J. Durechˇ 3, D.A. Oszkiewicz4, R. Behrend5, B. Carry2, M. Delbo’2, O. Adam6, V. Afonina7, R. Anquetin8,45, P. Antonini9, L. Arnold6, M. Audejean10, P. Aurard6, M. Bachschmidt6, B. Baduel6, E. Barbotin11, P. Barroy8,45, P. Baudouin12, L. Berard6, N. Berger13, L. Bernasconi14, J-G. Bosch15, S. Bouley8,45, I. Bozhinova16, J. Brinsfield17, L. Brunetto18, G. Canaud8,45, J. Caron19,20, F. Carrier21, G. Casalnuovo22, S. Casulli23, M. Cerda24, L. Chalamet86, S. Charbonnel25, B. Chinaglia22, A. Cikota26, F. Colas8,45, J-F. Coliac27, A. Collet6, J. Coloma28,29, M. Conjat2, E. Conseil30, R. Costa28,31, R. Crippa32, M. Cristofanelli33, Y. Damerdji87, A. Debackère86, A. Decock34, Q. Déhais36, T. Déléage35, S. Delmelle34, C. Demeautis37, M. Dró˙zd˙z38, G. Dubos8,45, T. Dulcamara6, M. Dumont34, R. Durkee39, R. Dymock40, A. Escalante del Valle85, N. Esseiva41, R. Esseiva41, M. Esteban24,42, T. Fauchez34, M. Fauerbach43, M. Fauvaud44,45, S. Fauvaud8,44,45, E. Forné28,46†, C. Fournel86, D. Fradet8,45, J. Garlitz47, O. Gerteis6, C. Gillier48, M. Gillon34, R. Giraud34, J-P. Godard8,45, R. Goncalves49, H. Hamanowa50, H. Hamanowa50, K. Hay16, S. Hellmich51, S. Heterier52,53, D. Higgins54, R. Hirsch4, G. Hodosan16, M. Hren26, A. Hygate16, N. Innocent6, H. Jacquinot55, S. Jawahar56, E. Jehin34, L. Jerosimic26, A. Klotz6,57,58, W. Koff59, P. Korlevic26, E. Kosturkiewicz4,38,88, P. Krafft6, Y. Krugly60, F. Kugel19, O. Labrevoir6, J. Lecacheux8,45, M. Lehký61, A. Leroy8,45,62,63, B. Lesquerbault6, M.J. Lopez-Gonzales64, M. Lutz6, B. Mallecot8,45, J. Manfroid34, F. Manzini32, A. Marciniak4, A. Martin65,66, B. Modave6, R. Montaigut8,45,48,63, J. Montier52,53, E. Morelle27, B. Morton16, S. Mottola51, R. Naves67, J. Nomen26, J. Oey68, W. Ogłoza38, M. Paiella33, H. Pallares28,69, A. Peyrot58, F. Pilcher70, J-F. Pirenne6, P. Piron6, M. Polinska´ 4, M. Polotto6, R. Poncy71, J.P. Previt53, F. Reignier72, D. Renauld6, D. Ricci34, F. Richard8,45, C. Rinner73, V. Risoldi33, D. Robilliard53, D. Romeuf74, G. Rousseau75, R. Roy76, J. Ruthroff77, P.A. Salom24,42, L. Salvador6, S. Sanchez26, T. Santana-Ros4, A. Scholz16, G. Séné6, B. Skiff78, K. Sobkowiak4, P. Sogorb79, F. Soldán80, A. Spiridakis35, E. Splanska6, S. Sposetti81, D. Starkey82, R. Stephens83, A. Stiepen34, R. Stoss26, J. Strajnic6, J-P. Teng58, G. Tumolo84, A. Vagnozzi33, B. Vanoutryve6, J.M. Vugnon8,45, B.D. Warner83, M. Waucomont6, O. Wertz34, M. Winiarski38†, and M. Wolf3 (Affiliations can be found after the references) Received 24-09-2012 / Accepted 22-10-2012 ABSTRACT Context. Asteroid modeling efforts in the last decade resulted in a comprehensive dataset of almost 400 convex shape models and their rotation states. This amount already provided a deep insight into physical properties of main-belt asteroids or large collisional families. Going into finer details (e.g., smaller collisional families, asteroids with sizes .20 km) requires knowledge of physical parameters of more objects. Aims. We aim to increase the number of asteroid shape models and rotation states. Such results are an important input for various further studies such as analysis of asteroid physical properties in different populations, including smaller collisional families, thermophysical modeling, and scaling shape models by disk-resolved images, or stellar occultation data. This provides, in combination with known masses, bulk density estimates, but constrains also theoretical collisional and evolutional models of the Solar System. Methods. We use all available disk-integrated optical data (i.e., classical dense-in-time photometry obtained from public databases and through a large collaboration network as well as sparse-in-time individual measurements from a few sky surveys) as an input for the convex inversion method, and derive 3D shape models of asteroids, together with their rotation periods and orientations of rotation axes. The key ingredient is the support of more that one hundred observers who submit their optical data to publicly available databases. arXiv:1510.07422v1 [astro-ph.EP] 26 Oct 2015 Results. We present updated shape models for 36 asteroids, for which mass estimates are currently available in the literature or their masses will be most likely determined from their gravitational influence on smaller bodies, which orbital deflection will be observed by the ESA Gaia astrometric mission. This was achieved by using additional optical data from recent apparitions for the shape optimization. Moreover, we also present new shape model determinations for 250 asteroids, including 13 Hungarias and 3 near-Earth asteroids. Key words. minor planets, asteroids: general – techniques: photometric – methods: observational – methods: numerical 1. Introduction sion method (LI) developed by Kaasalainen & Torppa (2001) and Kaasalainenet al. (2001). About one hundred models Asteroid modeling efforts in the last decade resulted in an ex- are based on disk-integrated dense-in-time optical data (e.g., tensive dataset of almost 400 convex shape models and rota- Torppa et al. 2003; Slivan et al. 2003; Michałowski et al. 2005; tion states (see the review by Durechˇ et al. 2015a). The ma- Marciniak et al. 2009, 2011). Combining dense-in-time data jority of these models was determined by the lightcurve inver- 1 J. Hanuš et al.: New and updated shape models of asteroids with sparse-in-time measurements from large sky surveys, or us- adaptive optics (AO) systems, the size of the model can be con- ing only sparse-in-time data increased the number of available strained, making it possible to determine the asteroid volume. shape models by a factor of 4 (Durechˇ et al. 2009; Hanuš et al. Note that even when the object is considerably nonconvex, the 2011, 2013a,c). Future data from Gaia, PanSTARRS, and LSST scaled convex model from occultations and AO data tends to should result in an increase of shape models by an order of compensate by average fitting to the disk-resolved data. As a at least one magnitude (Durechˇ et al. 2005). The methods that result, the overestimation in the volume is smaller than would will be used for analysis of these future data of unprecedented correspond to the convex hull. The volume can then provide, in amount and quality by the means of complex shape modeling combination with mass estimates, realistic values of bulk densi- are similar to those applied here and developed within the scope ties (Durechˇ et al. 2011; Hanuš et al. 2013b). of our recent studies. The mass is one of the most challenging parameter to mea- Most asteroid shape models derived by the lightcurve inver- sure for an asteroid. Mass estimates are now available for 280 as- sion method and their optical data are available in the Database teroids, but only 113 of these are more precise than 20% (Carry of Asteroid Models from Inversion Techniques (DAMIT1, 2012; Scheeres et al. 2015). However, the situation is expected Durechˇ et al. 2010). to improve significantly in a near future. The observations of the ESA Gaia astrometric satellite will provide masses accurate We would like to emphasize and acknowledge that the shape to better than 50% for ≈150 asteroids (and for ≈50 with an ac- modeling stands on the shoulders of 100s of observers, often am- curacy better than 10%, Mouret et al. 2007, 2008) by the orbit ateurs, that are regularly obtaining photometric data with their deflection method. The advantage of the masses determined by small and mid-sized telescopes, which significantly contributed Gaia is in the uniquenessof themission:we should obtaina com- to the large progress of the shape modeling field in the last prehensive sample with well-described biases (e.g., the current decade. Although there is much more sparse than dense data mass estimates are currently strongly biased towards the inner available, the latter will always remain important, because their main belt). much higher photometric accuracy and rotation coverage leads To maximize the possible outcome by the means of density to higher quality shape models. This is a typical example of determinations, we focus on determination of shape models for great interaction between the professional and amateur commu- asteroids, for which accurate mass estimates are available or will nity (Mousis et al. 2014). most likely be determined by Gaia. Moreover,it is also important Knowing the rotational parameters and shapes of asteroids is to update shape models for such asteroids by using recently ob- very important for numerous applications. The large amount of tained optical data. Doing so, we can provide better constraints currently known asteroid models provided already a deep insight on the rotational phase (i.e., on the asteroid orientation, which into physical properties of main-belt asteroids and large colli- is important for scaling the size) of these asteroids due to the sional families: (i) an excess of prograde rotators within main- improvement of the rotation period, and more accurate rotation ∼ belt asteroids (MBAs) larger than 50 km in diameter, predicted state and shape parameters. by numerical simulations (Johansen & Lacerda 2010), was con- Convex models, together with thermal infrared observations, firmed by Kryszczynska´ et al. (2007);Hanuš et al. (2011);(ii) an have also been used as inputs for thermophysical modeling, en- excess of retrograde rotators within near-Earth asteroids (NEAs) abling the determination of geometric visible albedo, size and is consistent with the fact that most of the NEAs come from surface properties (e.g., Müller et al. 2011; Hanuš et al. 2015). the ν6 resonance (La Spina et al. 2004). To enter the ν6 reso- This application is particularly important because it can make ff 2 nance via Yarkovsky e ect the object must be a retrograde use of the large sample of infrared data for more than 100000 rotator; (iii) an anisotropy of spin-axis directions of MBAs as- asteroids acquired by the NASA’s Wide-field Infrared Survey .