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Peculiar Betulia Revisited: A Near-Earth Asteroid with a Bare-Rock Surface?

Harris, Alan und Mueller, Michael und Delbo, Marco und Bus, Schelte (2005) Peculiar Betulia Revisited: A Near-Earth Asteroid with a Bare-Rock Surface? In: Bulletin of the American Astronomical Society, 37 (3), Seite 628. American Astronomical Society. 37th DPS-Meeting of the American Astronomical Society, 2005-09-04 - 2005-09-09, Cambridge (UK).

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The small C-type asteroid (1580) Betulia is an unusual near-Earth object (NEO) with a lightcurve that changes dramatically with changing solar phase angle, presumably due to a highly irregular shape and/or unusual topographic features. Earlier thermal-infrared observations indicated a surface of high thermal inertia, which is consistent with a lack of thermally insulating regolith. Absence of regolith might be expected in the case of small NEOs with weak gravities, which may be unable to retain collisional debris. However, recent infrared observations of other asteroids of comparable size indicate that regolith is normally present. Knowledge of the thermal properties of NEOs 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 NEOs. We observed Betulia in June 2002 with the 3-m NASA Infrared Telescope Facility. Our database is sufficiently broad to allow the use of more sophisticated thermal models than were available for earlier radiometric observations. It is important to bear the unusual nature of Betulia in mind when interpreting observational data. Fits to our data 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 Jm<sup>-2</sup>s<sup>-0.5</sup>K<sup>-1</sup>. It is difficult to reconcile our results with those of earlier work, which indicate a larger diameter for Betulia and a high-thermal-inertia surface of bare rock. While the thermal inertias of NEOs appear to be significantly higher than those of large main-belt asteroids, to our knowledge no convincing evidence has yet been found for very high-thermal-inertia “bare-rock” surfaces amongst NEOs: further observations are required to probe smaller objects.

Dokumentart:Konferenzbeitrag (Vortrag)
Titel:Peculiar Betulia Revisited: A Near-Earth Asteroid with a Bare-Rock Surface?
AutorenInstitution oder E-Mail-AdresseAutoren-ORCID
Delbo, MarcoOsservatorio Astronomico di Torino, Pino Torinese, ItalienNICHT SPEZIFIZIERT
Bus, SchelteInstitute for Astronomy, Hilo, HI, USANICHT SPEZIFIZIERT
Datum:September 2005
Erschienen in:Bulletin of the American Astronomical Society
Referierte Publikation:Nein
In Open Access:Nein
In ISI Web of Science:Nein
Seitenbereich:Seite 628
Verlag:American Astronomical Society
Stichwörter:Asteroids, near-Earth asteroids, infrared observations, thermal models
Veranstaltungstitel:37th DPS-Meeting of the American Astronomical Society
Veranstaltungsort:Cambridge (UK)
Veranstaltungsart:internationale Konferenz
Veranstaltungsdatum:2005-09-04 - 2005-09-09
Veranstalter :AAS Division for Planetary Sciences
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: Harris, Prof. Alan
Hinterlegt am:11 Dez 2005
Letzte Änderung:27 Apr 2009 04:45

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