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Small Bodies in the Solar System

Characterizing their Physical Properties through Earth-Based Observations

Comets, asteroids, Kuiper Belt objects (KBOs) and some moons of the major planets are considered among the most primordial bodies that survived widely unaltered from the formation period of our planetary system and that are still observable from Earth today. They represent the "memory" on the most original material and on physical conditions that prevailed during the formation of our solar system some 4.6 billion years ago.

> Science Objectives
> The Team
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Figure 1: The Rosetta target comet 67P/Churyumov- Gerasimenko, observed with the FORS2 instrument at the 8.2m Antu telescope of the Very Large Telescope Observatory VLT of the European Southern Observatory ESO at Cerro Paranal in Chile. By the time of the observations the comet was at 5.6 AU solar and 4.6 AU Earth distance. The comet appears point-like and is mark by a circle close to the center of the image. Most objects seen in the images are background stars of the Milky Way.

Science Objectives

The research project aims at the characterization of the physical properties of these bodies, i.e. their sizes, shapes, albedo, temperatures, colours and surface composition as well as the production of gas and dust in case the bodies show activity like comets do. These physical parameters are determined from observations using optical 4-8m telescopes ( <Calar Alto, <ESO La Silla, <ESO VLT, <Rozhen, <La Palma ) and radio telescopes ( <APEX, <SMT, in the future also <ALMA ) equipped with modern instruments for measurements in the visible, infrared and sub-/mm wavelength range. Furthermore, instrumentation onboard of Earth satellites ( <Herschel, <HST, <Spitzer ) or airplanes ( <SOFIA ) are or will be used. Special attention is paid to target objects of space missions - like for instance >Rosetta, >Dawn, <Deep Impact, <Stardust, and <New Horizons -, in particular for missions with MPS share in the scientific spacecraft instrumentation.

This project continues along the line of research performed since 1983 by the MPAe/MPS project >GBOC (Ground-Based Observations of Comets) under supervision and guidance of Prof. Klaus Jockers.

Figure 2: The Rosetta target comet 67P/Churyumov- Gerasimenko when active and surrounded by a coma of gas and dust. The brightness distribution in the coma is non-uniform. This indicates enhanced gas and dust production at various locations at the nucleus surface.

Figure 3: The dwarf planet binary Pluto-Charon (left panel, exposed in the near-infrared K band using the NACO instrument the Very Large Telescope Observatory VLT of the European Southern Observatory ESO at Cerro Paranal in Chile.. The near-infrared spectrum (right panel) of both KBOs displays prominent absorptions bands of various ices at the surface of the objects. The curvature of the spectra in J and H bands (upper part of the spectrum) is due to refraction of the infrared light in the atmosphere of the Earth.

The following observing projects are currently performed:

  • Nucleus parameters of the Rosetta target comet 67P/Churyumov-Gerasimenko
  • Dust production in comet 67P/Churyumov-Gerasimenko
  • Supervolatile ices in cometary nuclei
  • Physical properties of cometary dust
  • Activity of the DeepImpact comet 9P/Tempel 1
  • Physical properties of KBOS and Trojans
  • Surface composition of Pluto, Charon, Triton
  • Taxonomy of near-Earth asteroids
  • Activity of the comet-asteroid Elst-Pizarro

Figure 4: Linear polarization and opposition brightening of Kuiper Belt objects for different phase angles Sun-object-observer. Model calculations of the measurements indicate that at least two different materials exist at the surface of the bodies.

The Team

MPS scientists working on these projects
Hermann BöhnhardtAll observing projects using optical telescopes, Herschel, Spitzer, Sofia, HST
Paul HartoghAll observing projects using sub-/mm telescopes, Herschel, Sofia
Manuela LippiHigh dispersion near-IR spectroscopy of comets
Chemeda EjetaPolarimetry of small body surfaces
Christopher JarchowObserving projects using sub-/mm teleskopes, Herschel, Sofia
Andreas NathuesObserving projects on asteroids
Silvia ProtopapaPluto-Charon, Triton and Kuiper Belt objects, Herschel
Miriam RengelObserving projects using sub-/mm teleskopes, Herschel, Sofia
Juan SanchezObserving projects on asteroids
Cecilia TubianaRosetta target comet 67P/Churyumov-Gerasimenko
Jean-Baptiste VincentDust comae of comets
Collaborating scientists at other research institutes
Jessica AgarwalNoordwijk
Stefano BagnuloArmagh
Luis BarreraSantiago de Chile
Antonella BarucciParis
Tanyu BonevSofia
Dale CruikshankMoffett Field
Elisabetta DottoRome
Mike GaffeyCambridge
Will GrundyFlagstaff
Olivier HainautGarching
Ulli KäuflGarching
Ludmilla KolokolovaCollege Park
Luisa LaraGranada
Emmanuel LellouchParis
Javier LicandroLa Palma
Karen MeechHonolulu
Karri MuinonenHelsinki
Thomas MüllerGarching
Mike MummaGreenbelt
Jose-Luis OrtizGranada
Dina PrialnikTel Aviv
John StansberryTucson
GianPaolo TozziFlorence
Diane WoodenMoffett Field

Figure 5: The DeepImpact event at comet 9P/Tempel 1 in 2005. The 4 panels in the upper part show the expansion of the ejecta cloud produced by the space probe impact at the comet. The coma light from normal activity of the nucleus was removed by image processing techniques. The pair of images at the bottom shows linear structures of dust (marked with letters A, B, C, D, E, F, G, H, I) in the cometary coma that are caused by continuous normal activity from areas of enhanced dust emission at the nucleus surface. On 5 July 2007 the ejecta cloud from the DeepImpact event is superposed to the normal activity of the comet.

Related Links

> GBOC Homepage at MPS

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