@article{0962368513cc4f8e94c3a07b38c6c552,
title = "The organic composition of C/2001 A2 (LINEAR). II. Search for heterogeneity within a comet nucleus",
abstract = "The nucleus of Comet C/2001 A2 (LINEAR) split several times during its recent apparition, presenting an unusual opportunity to search for chemical differences in freshly exposed material. We conducted this search using NIRSPEC at the W.M. Keck Observatory on four dates in 2001: 9.5 and 10.5 July and 4.4 and 10.5 August. We detected the R0 and R1 lines of the ν3 vibrational band of CH4 near 3.3 μm on all dates. The R2 line was detected on 4.4 and 10.5 August. When we compare production rates of CH4 to H2O, we find evidence of a significant enhancement in August relative to that found in July. H2CO was securely detected via its ν1 and ν5 bands on 9.5 July. On 10.5 July, H2CO emission was much weaker, and its mixing ratio had dropped by a factor of about four. The mixing ratios for other detected volatile species did not change significantly over the course of the observations. We discuss the implications of this evidence for chemical heterogeneity in the nucleus of Comet C/2001 A2.",
author = "Gibb, {Erika L.} and DiSanti, {Michael A.} and Karen Magee-Sauer and {Dello Russo}, Neil and Bonev, {Boncho P.} and Mumma, {Michael J.}",
note = "Funding Information: E.L.G. gratefully acknowledges support from the NRC under her Resident Research Associateship at NASA's Goddard Space Flight Center. K.M.-S. was supported by the NSF Research at Undergraduate Institutions Program (AST-009841). We also acknowledge NASA's Planetary Astronomy program support for M.J.M. and B.P.B. (RTOP 344-32-30-07) and M.A.D. (RTOP 344-32-98, and NAG5-7905, NAG5-12208), and NASA's Planetary Atmospheres program support for N.D.R. (NAG5-10795, NAG5-12285) and M.A.D. (RTOP 344-33-55). We thank the NASA Keck TAC for awarding observing time to our Target-of-Opportunity proposal and the Observatory Director (F. Chaffee) for rescheduling Keck-2. We thank I. McLean and D. Sprayberry for acquiring the 4.4 August data. We also thank Geronimo Villanueva for providing GENLN2 telluric model spectra. Data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. The authors recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community.",
year = "2007",
month = may,
doi = "10.1016/j.icarus.2006.11.009",
language = "English (US)",
volume = "188",
pages = "224--232",
journal = "Icarus",
issn = "0019-1035",
publisher = "Academic Press Inc.",
number = "1",
}