Published November 18, 2014
| Version v1
Journal article
The small binary asteroid (939) Isberga
Creators
- Carry, B.
- Matter, A.
- Scheirich, P
- Pravec, P
- Molnar, L.
- Mottola, S.
- Carbognani, A.
- Jehin, K
- Marciniak, A.
- Binzel, R.P.
- Demeo, F.E.
- Birlan, M.
- Delbo, M.
- Barbotin, E.
- Behrend, R.
- Bonnardeau, M.
- Colas, F
- Farissier, P.
- Fauvaud, M.
- Fauvaud, S.
- Gillier, C
- Gillon, M.
- Hellmich, S.
- Hirsch, R
- Leroy, A
- Manfroid, J.
- Montier, J
- Morelle, E.
- Richard, F
- Sobkowiak, K.
- Strajnic, J.
- Vachier, Frédéric
Contributors
Others:
- European Space Astronomy Centre (ESAC) ; Agence Spatiale Européenne = European Space Agency (ESA)
- Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE) ; Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris ; Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)
- Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ) ; Observatoire des Sciences de l'Univers de Grenoble (OSUG) ; Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
- Max-Planck-Institut für Radioastronomie (MPIFR)
- Astronomical Institute of the Czech Academy of Sciences (ASU / CAS) ; Czech Academy of Sciences [Prague] (CAS)
- Department of Physics and Astronomy [Grand Rapids) ; Calvin College Burton
- DLR Institut für Planetenforschung ; Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR)
- Astronomical Observatory of the Autonomous Region of the Aosta Valley (OAVDA)
- Institut d'Astrophysique et de Géophysique [Liège] ; Université de Liège
- Astronomical Observatory [Poznan] ; Adam Mickiewicz University in Poznań (UAM)
- Department of Earth, Atmospheric and Planetary Sciences [MIT, Cambridge] (EAPS) ; Massachusetts Institute of Technology (MIT)
- Harvard-Smithsonian Center for Astrophysics (CfA) ; Harvard University [Cambridge]-Smithsonian Institution
- UNS-CNRS-Observatoire de la Côte d'Azur ; UNS-CNRS-Observatoire de la Côte d'Azur
- Association des Utilisateurs de Détecteurs Electroniques
- CdR & CdL group
- Geneva Observatory ; Université de Genève = University of Geneva (UNIGE)
- Club d'Astronomie Lyon Ampéré [Vaulx-en-Velin] (CALA)
- Association T60, Observatoire Midi-Pyrénées ; Observatoire Midi-Pyrénées (OMP) ; Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3) ; Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3) ; Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France
- Observatoire du Bois de Bardon
Description
In understanding the composition and internal structure of asteroids, their density is perhaps the most diagnostic quantity. We aim here at characterizing the surface composition, mutual orbit, size, mass, and density of the small main-belt binary asteroid (939) Isberga. For that, we conduct a suite of multi-technique observations, including optical lightcurves over many epochs, near-infrared spectroscopy, and interferometry in the thermal infrared. We develop a simple geometric model of binary systems to analyze the interferometric data in combination with the results of the lightcurve modeling. From spectroscopy, we classify Ibserga as a Sq-type asteroid, consistent with the albedo of View the MathML source0.14-0.06+0.09 (all uncertainties are reported as 3-σ range) we determine (average albedo of S-types is 0.197 ± 0.153, see Pravec et al. (Pravec et al. [2012]. Icarus 221, 365–387). Lightcurve analysis reveals that the mutual orbit has a period of 26.6304 ± 0.0001 h, is close to circular (eccentricity lower than 0.1), and has pole coordinates within 7° of (225°, +86°) in Ecliptic J2000, implying a low obliquity of View the MathML source1.5-1.5+6.0deg. The combined analysis of lightcurves and interferometric data allows us to determine the dimension of the system and we find volume-equivalent diameters of View the MathML source12.4-1.2+2.5km and View the MathML source3.6-0.3+0.7km for Isberga and its satellite, circling each other on a 33 km wide orbit. Their density is assumed equal and found to be View the MathML source2.91-2.01+1.72gcm-3, lower than that of the associated ordinary chondrite meteorites, suggesting the presence of some macroporosity, but typical of S-types of the same size range (Carry [2012]. Planet. Space Sci. 73, 98–118). The present study is the first direct measurement of the size of a small main-belt binary. Although the interferometric observations of Isberga are at the edge of MIDI capabilities, the method described here is applicable to others suites of instruments (e.g., LBT, ALMA).
Abstract
International audienceAdditional details
Identifiers
- URL
- https://hal.sorbonne-universite.fr/hal-01122881
- URN
- urn:oai:HAL:hal-01122881v1
Origin repository
- Origin repository
- UNICA