TY - JOUR
T1 - Mineralogical characterization of Baptistina Asteroid Family
T2 - Implications for K/T impactor source
AU - Reddy, Vishnu
AU - Carvano, Jorge M.
AU - Lazzaro, Daniela
AU - Michtchenko, Tatiana A.
AU - Gaffey, Michael J.
AU - Kelley, Michael S.
AU - Mothé-Diniz, Thais
AU - Alvarez-Candal, Alvaro
AU - Moskovitz, Nicholas A.
AU - Cloutis, Edward A.
AU - Ryan, Erin L.
N1 - Funding Information:
V.R., M.J.G. were supported by NASA NEOO Program Grant NNX07AL29G and NASA Planetary Geology and Geophysics Grant NNX07AP73G . V.R. was also supported by a PCI/MCT fellowship during his stay at Observatório Nacional. J.M.C., D.L. and T.M.D. were supported by several fellowship and grants by the Brazilian National Research Council – CNPq and the Rio de Janeiro Science Foundation – FAPERJ. T.A.M. work has been supported by the Brazilian National Research Council – CNPq, the São Paulo State Science Foundation – FAPESP; she gratefully acknowledges the support of the Computation Center of the University of São Paulo (LCCA-USP) and of the Astronomy Department of the IAG/USP, for the use of their facilities. The research utilizes spectra acquired by C.M. Pieters, and P. Hudson with the NASA RELAB facility at Brown University. The authors would like to thank Bill Bottke and Tasha Dunn for their reviews and comments to improve the manuscript; Martin Hynes, Bobby Bus, M. Schaal, and Driss Takir for their support in this research. We thank the IRTF TAC for awarding time to this project, and to the IRTF TOs and MKSS staff for their support.
PY - 2011/11
Y1 - 2011/11
N2 - Bottke et al. [Bottke, W.F., Vokrouhlicky, D., Nesvorný, D., 2007. Nature 449, 48-53] linked the catastrophic formation of Baptistina Asteroid Family (BAF) to the K/T impact event. This linkage was based on dynamical and compositional evidence, which suggested the impactor had a composition similar to CM2 carbonaceous chondrites. However, our recent study [Reddy, V., Emery, J.P., Gaffey, M.J., Bottke, W.F., Cramer, A., Kelley, M.S., 2009. Meteorit. Planet. Sci. 44, 1917-1927] suggests that the composition of (298) Baptistina is similar to LL-type ordinary chondrites rather than CM2 carbonaceous chondrites. This rules out any possibility of it being related to the source of the K/T impactor, if the impactor was of CM-type composition. Mineralogical study of asteroids in the vicinity of BAF has revealed a plethora of compositional types suggesting a complex formation and evolution environment. A detailed compositional analysis of 16 asteroids suggests several distinct surface assemblages including ordinary chondrites (Gaffey SIV subtype), primitive achondrites (Gaffey SIII subtype), basaltic achondrites (Gaffey SVII subtype and V-type), and a carbonaceous chondrite. Based on our mineralogical analysis we conclude that (298) Baptistina is similar to ordinary chondrites (LL-type) based on olivine and pyroxene mineralogy and moderate albedo. S-type and V-type in and around the vicinity of BAF we characterized show mineralogical affinity to (8) Flora and (4) Vesta and could be part of their families. Smaller BAF asteroids with lower SNR spectra showing only a 'single' band are compositionally similar to (298) Baptistina and L/LL chondrites. It is unclear at this point why the silicate absorption bands in spectra of asteroids with formal family definition seem suppressed relative to background population, despite having similar mineralogy.
AB - Bottke et al. [Bottke, W.F., Vokrouhlicky, D., Nesvorný, D., 2007. Nature 449, 48-53] linked the catastrophic formation of Baptistina Asteroid Family (BAF) to the K/T impact event. This linkage was based on dynamical and compositional evidence, which suggested the impactor had a composition similar to CM2 carbonaceous chondrites. However, our recent study [Reddy, V., Emery, J.P., Gaffey, M.J., Bottke, W.F., Cramer, A., Kelley, M.S., 2009. Meteorit. Planet. Sci. 44, 1917-1927] suggests that the composition of (298) Baptistina is similar to LL-type ordinary chondrites rather than CM2 carbonaceous chondrites. This rules out any possibility of it being related to the source of the K/T impactor, if the impactor was of CM-type composition. Mineralogical study of asteroids in the vicinity of BAF has revealed a plethora of compositional types suggesting a complex formation and evolution environment. A detailed compositional analysis of 16 asteroids suggests several distinct surface assemblages including ordinary chondrites (Gaffey SIV subtype), primitive achondrites (Gaffey SIII subtype), basaltic achondrites (Gaffey SVII subtype and V-type), and a carbonaceous chondrite. Based on our mineralogical analysis we conclude that (298) Baptistina is similar to ordinary chondrites (LL-type) based on olivine and pyroxene mineralogy and moderate albedo. S-type and V-type in and around the vicinity of BAF we characterized show mineralogical affinity to (8) Flora and (4) Vesta and could be part of their families. Smaller BAF asteroids with lower SNR spectra showing only a 'single' band are compositionally similar to (298) Baptistina and L/LL chondrites. It is unclear at this point why the silicate absorption bands in spectra of asteroids with formal family definition seem suppressed relative to background population, despite having similar mineralogy.
KW - Asteroids
KW - Impact processes
KW - Mineralogy
KW - Spectroscopy
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U2 - 10.1016/j.icarus.2011.08.027
DO - 10.1016/j.icarus.2011.08.027
M3 - Article
AN - SCOPUS:80053446727
SN - 0019-1035
VL - 216
SP - 184
EP - 197
JO - Icarus
JF - Icarus
IS - 1
ER -