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The surface properties of small asteroids: Peculiar Betulia - a case study

Harris, Alan W. und Mueller, Michael und Delbo, Marco und Bus, Schelte J. (2005) The surface properties of small asteroids: Peculiar Betulia - a case study. Icarus: International Journal of Solar System Studies, 179 (1), Seiten 95-108. Elsevier. DOI: 10.1016/j.icarus.2005.05.010 ISSN 0019-1035

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We present the results of extensive thermal–infrared observations of the C-type near-Earth Asteroid (1580) Betulia obtained in June 2002 with the 3-m NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. Betulia is a highly unusual object for which earlier radiometric observations, interpreted on the basis of simple thermal models, indicated a surface of high thermal inertia. A high thermal inertia implies a lack of thermally insulating regolith. Radiometric observations of other asteroids of comparable size indicate that regolith is present in nearly all cases. Knowledge of the surface thermal properties of small near-Earth asteroids is crucial for meaningful calculations of the Yarkovsky effect, which is invoked to explain the delivery of collisional fragments from the main belt into near-Earth orbits, and apparently has a significant influence on the orbital evolution of potentially hazardous near-Earth asteroids. Furthermore, apart from being an indicator of the presence of thermally insulating regolith on the surface of an asteroid, the thermal inertia determines the magnitude of the diurnal temperature variation and is therefore of great importance in the design of instrumentation for lander missions to small asteroids. In the case of Betulia our database is sufficiently broad to allow the use of more sophisticated thermal models than were available for earlier radiometric observations. The measured fluxes have been fitted with thermal-model emission continua to determine the asteroid's size and geometric albedo, pv. Fits obtained with a new thermophysical model imply an effective diameter of 4.57±0.46 km and an albedo of 0.077±0.015 and indicate a moderate surface thermal inertia of around 180 J m<sup>−2</sup> s<sup>−0.5</sup> K<sup>−1</sup>. It is difficult to reconcile our results with earlier work, which indicate a larger diameter for Betulia and a high-thermal-inertia surface of bare rock.

Zusätzliche Informationen: LIDO-Berichtsjahr=2005,
Titel:The surface properties of small asteroids: Peculiar Betulia - a case study
AutorenInstitution oder E-Mail-AdresseAutoren-ORCID
Delbo, MarcoOsservatorio Astronomico di Torino, Pino Torinese, ItalyNICHT SPEZIFIZIERT
Bus, Schelte J.Institute for Astronomy, Hilo, HI, USANICHT SPEZIFIZIERT
Erschienen in:Icarus: International Journal of Solar System Studies
Referierte Publikation:Ja
In Open Access:Nein
In ISI Web of Science:Ja
DOI : 10.1016/j.icarus.2005.05.010
Seitenbereich:Seiten 95-108
Stichwörter:Asteroids, Infrared observations, Photometry, Spectrophotometry
HGF - Forschungsbereich:Verkehr und Weltraum (alt)
HGF - Programm:Weltraum (alt)
HGF - Programmthema:W EW - Erforschung des Weltraums
DLR - Schwerpunkt:Weltraum
DLR - Forschungsgebiet:W EW - Erforschung des Weltraums
DLR - Teilgebiet (Projekt, Vorhaben):W - Vorhaben Asteroiden und Kometen (alt)
Standort: Berlin-Adlershof
Institute & Einrichtungen:Institut für Planetenforschung > Asteroiden und Kometen
Hinterlegt von: Pieth, Susanne
Hinterlegt am:06 Dez 2005
Letzte Änderung:14 Jan 2010 20:19

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