76th Annual Meteoritical Society Meeting (2013) 5124.pdf

IDENTIFICATION OF A POSSIBLE H-CHONDRITE FAMILY. M. J. Gaffey1,2 and S. K. Fieber-Beyer1,2. 1Space Studies Depart- ment, John D. Odegard School of Aerospace Sciences, University of North Dakota, Grand Forks, ND 58202. 2Visiting astronomer at the IRTF under contract from NASA, operated by the Univ. of Hi., Mauna Kea; [email protected]; [email protected].

Introduction: Based on dynamical and spectral parameters, asteroid (6) Hebe was identified as the probable parent body of the H-chondrites [1]. The Portales Valley meteorite [2-4] and subsequent dynamical analysis [5] strengthened this conclusion. Hebe is located near the intersection of the 3:1 res- onance () and the ν6 proper motion resonance, both of which should be major sources of meteorites [6, 7]. Hebe has no observed [5]. Investigation of 3:1` Kirkwood Gap : For the past several years we have carried out a spectral investigation of as- teroids adjacent to the 3:1 mean motion resonance, with the goal of identifying possible meteorite parent bodies [8-10]. H-chondrite Assemblages: Our initial survey identified an additional H-type assemblage (695) Bella located near (6) Hebe. We suggested that Bella was a “daughter” (i.e., a fragment) or a “sister” of Hebe (i.e., from the same nebular compositional reser- voir) [8]. Our spectral survey of asteroids within the “feeding zone” of the 3:1 Kirkwood Gap has now examined 40 objects. Two additional H-type assemblages have been identified. These are both located in the upper half of the inclination distribution. Asteroid a (AU)11 i (°)11 Diam.(km)11 2.246 14.7 185 695 Bella 2.540 13.9 48 1166 Sakuntala 2.539 18.9 29 1607 Mavis 2.549 8.6 12 Conclusions: We suggest that these four objects are members of a relatively dispersed (old?) asteroid family derived from a major collisional event on asteroid (6) Hebe. Objects near the resonance are subject to significant changes in which in turn allows significant changes in [12] which may explain the lower inclination of (1607) Mavis. The record of impact cratering on the H-chondrite parent body suggests that it may have suffered a catastrophic size reduction at ~3600 Myr ago [12]. Alternately, these four objects may derive from a unique nebular chemical reservoir located near the inter- section of the 3:1 mean motion resonance with the ν6 proper mo- tion resonance. This seems less likely. Acknowledgements: This work was supported by NASA Plane- tary Geology and Geophysics Grants NNX10AG45G and NNX11AN84G. References: [1] Gaffey M. J. and Gilbert S. L. 1998. MAPS 33: 1281-1295. [2] Kring D. A. et al. 1999. MAPS 34:663-669. [3] Rubin A. E. et al. 2001. GCA 65:323–342. [4] Ruzicka A. et al. 2005. MAPS 40:261–295. [5] Bottke W. F. et al. 2010. 42nd DPS Meeting, Abstract 46.06. [6] Farinella P. et al. 1993. Icarus 101:174-187. [7] Farinella P. et al. 1998. Icarus 132:378-387. [8] Fieber-Beyer S. K. et al. 2011. Icarus 213:524-537. [9] Fieber-Beyer S. K. and Gaffey M. J. 2011. Icarus 214:645-651. [10] Fieber-Beyer S. K. 2012. Icarus 221:593-602. [11] JPL Small Body Data Browser [12] Yoshikawa M. 1992. Celest. Mech. & Dynam. Ast. 54:287-290. [13] Wittmann A. et al. 2010. JGR 115:E07009, doi:10.1029/2009JE003433.