Rotating dust particles in the coma of comet 67P/Churyumov-Gerasimenko

¹ INAF–Osservatorio Astronomico, via Tiepolo 11, 34143 Trieste, Italy
e-mail: fulle@oats.inaf.it
² INAF–Istituto di Astrofisica e Planetologia Spaziali, Area Ricerca Tor Vergata, via Fosso del Cavaliere 100, 00133 Rome, Italy
³ University of Padova, CISAS, via Venezia 15, 35100 Padova, Italy
⁴ Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
⁵ Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
⁶ LESIA, Obs. de Paris, CNRS, Univ. Paris 06, Univ. Paris-Diderot, 5 place J. Janssen, 92195 Meudon, France
⁷ Università degli Studi di Napoli Parthenope, Dip. di Scienze e Tecnologie, CDN IC4, 80143 Naples, Italy
⁸ Department of Physics and Astronomy, Padova University, Vicolo dell’Osservatorio 3, 35122 Padova, Italy
⁹ Laboratoire d’Astrophysique de Marseille, UMR 7326, CNRS & Aix-Marseille Université, 13388 Marseille, France
¹⁰ Centro de Astrobiologia (INTA-CSIC), 28691 Villanueva de la Canada, Madrid, Spain
¹¹ International Space Science Institute, Hallerstrasse 6, 3012 Bern, Switzerland
¹² Scientific Support Office, European Space Agency, 2201 Noordwijk, The Netherlands
¹³ Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
¹⁴ PAS Space Research Center, Bartycka 18A, 00716 Warszawa, Poland
¹⁵ Institute for Geophysics and Extraterrestrial Physics, 38106 TU Braunschweig, Germany
¹⁶ Department of Astronomy, University of Maryland, College Park, MD 20742-2421, USA
¹⁷ LATMOS, CNRS/UVSQ/IPSL, 11 boulevard d’Alembert, 78280 Guyancourt, France
¹⁸ INAF–Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
¹⁹ CNR-IFN UOS Padova LUXOR, via Trasea 7, 35131 Padova, Italy
²⁰ Department of Mech. Engineering – University of Padova, via Venezia 1, 35131 Padova, Italy
²¹ UNITN, Universitá di Trento, via Mesiano, 77, 38100 Trento, Italy
²² Institute of Planetary Research, DLR, Rutherfordstrasse 2, 12489 Berlin, Germany
²³ Institute for Space Science, Nat. Central Univ., 300 Chung Da Rd., 32054 Chung-Li, Taiwan
²⁴ ESA-ESAC, Camino Bajo del Castillo s/n., 28692 Villanueva de la Cañada, Madrid, Spain
²⁵ Department of Physics, University of Padova, 35131 Padova, Italy
²⁶ Institut für Datentechnik und Kommunikationsnetze, 38106 Braunschweig, Germany
²⁷ Dept. of Information Engineering – Padova University, via Gradenigo 6, 35131 Padova, Italy
²⁸ Instituto Nacional de Tecnica Aeroespacial, Carretera de Ajalvir, p.k. 4, 28850 Torrejon de Ardoz, Madrid, Spain
²⁹ Physikalisches Institut, Sidlerstrasse 5, University of Bern, 3012 Bern, Switzerland

Received: 23 March 2015
Accepted: 25 June 2015

Abstract

Context. During September and October 2014, the OSIRIS cameras onboard the ESA Rosetta mission detected millions of single particles. Many of these dust particlesappear as long tracks (due to both the dust proper motion and the spacecraft motion during the exposure time) with a clear brightness periodicity.

Aims. We interpret the observed periodic features as a rotational and translational motion of aspherical dust grains.

Methods. By counting the peaks of each track, we obtained statistics of a rotation frequency. We compared these results with the rotational frequency predicted by a model of aspherical dust grain dynamics in a model gas flow. By testing many possible sets of physical conditions and grain characteristics, we constrained the rotational properties of dust grains.

Results. We analyzed on the motion of rotating aspherical dust grains with different cross sections in flow conditions corresponding to the coma of 67P/Churyumov-Gerasimenko qualitatively and quantitatively. Based on the OSIRIS observations, we constrain the possible physical parameters of the grains.