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Composition of 298 Baptistina: Implications for the K/T impactor link
Author(s) -
Reddy Vishnu,
Emery Joshua P.,
Gaffey Michael J.,
Bottke William F.,
Cramer Abigail,
Kelley Michael S.
Publication year - 2009
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/j.1945-5100.2009.tb02001.x
Subject(s) - asteroid , chondrite , meteorite , geology , asteroid belt , parent body , albedo (alchemy) , allende meteorite , astrobiology , chondrule , ordinary chondrite , carbonaceous chondrite , near earth object , astrophysics , geochemistry , physics , art , performance art , art history
— Bottke et al. (2007) suggested that the breakup of the Baptistina asteroid family (BAF) 160 +30 / ‐20 Myr ago produced an “asteroid shower” that increased by a factor of 2–3 the impact flux of kilometer‐sized and larger asteroids striking the Earth over the last ˜120 Myr. This result led them to propose that the impactor that produced the Cretaceous/Tertiary (K/T) mass extinction event 65 Myr ago also may have come from the BAF. This putative link was based both on collisional/dynamical modeling work and on physical evidence. For the latter, the available broadband color and spectroscopic data on BAF members indicate many are likely to be dark, low albedo asteroids. This is consistent with the carbonaceous chondrite‐like nature of a 65 Myr old fossil meteorite (Kyte 1998) and with chromium from K/T boundary sediments with an isotopic signature similar to that from CM2 carbonaceous chondrites. To test elements of this scenario, we obtained near‐IR and thermal IR spectroscopic data of asteroid 298 Baptistina using the NASA IRTF in order to determine surface mineralogy and estimate its albedo. We found that the asteroid has moderately strong absorption features due to the presence of olivine and pyroxene, and a moderately high albedo (˜20%). These combined properties strongly suggest that the asteroid is more like an S‐type rather than Xc‐type (Mothé‐Diniz et al. 2005). This weakens the case for 298 Baptistina being a CM2 carbonaceous chondrite and its link to the K/T impactor. We also observed several bright (V Mag. ≤16.8) BAF members to determine their composition.