skip to main content

SciTech ConnectSciTech Connect

Title: C/2013 R1 (Lovejoy) at IR wavelengths and the variability of CO abundances among Oort Cloud comets

We report production rates, rotational temperatures, and related parameters for gases in C/2013 R1 (Lovejoy) using the Near InfraRed SPECtrometer at the Keck Observatory, on six UT dates spanning heliocentric distances (R{sub h} ) that decreased from 1.35 AU to 1.16 AU (pre-perihelion). We quantified nine gaseous species (H{sub 2}O, OH*, CO, CH{sub 4}, HCN, C{sub 2}H{sub 6}, CH{sub 3}OH, NH{sub 3}, and NH{sub 2}) and obtained upper limits for two others (C{sub 2}H{sub 2} and H{sub 2}CO). Compared with organics-normal comets, our results reveal highly enriched CO, (at most) slightly enriched CH{sub 3}OH, C{sub 2}H{sub 6}, and HCN, and CH{sub 4} consistent with {sup n}ormal{sup ,} yet depleted, NH{sub 3}, C{sub 2}H{sub 2}, and H{sub 2}CO. Rotational temperatures increased from ∼50 K to ∼70 K with decreasing R{sub h} , following a power law in R{sub h} of –2.0 ± 0.2, while the water production rate increased from 1.0 to 3.9 × 10{sup 28} molecules s{sup –1}, following a power law in R{sub h} of –4.7 ± 0.9. The ortho-para ratio for H{sub 2}O was 3.01 ± 0.49, corresponding to spin temperatures (T {sub spin}) ≥ 29 K (at the 1σ level). The observed spatial profiles for these emissionsmore » showed complex structures, possibly tied to nucleus rotation, although the cadence of our observations limits any definitive conclusions. The retrieved CO abundance in Lovejoy is more than twice the median value for comets in our IR survey, suggesting this comet is enriched in CO. We discuss the enriched value for CO in comet C/2013 R1 in terms of the variability of CO among Oort Cloud comets.« less
Authors:
; ; ; ;  [1] ; ;  [2] ;  [3] ;  [4]
  1. Goddard Center for Astrobiology, NASA GSFC, MS 690, Greenbelt, MD 20771 (United States)
  2. Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States)
  3. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States)
  4. Department of Physics and Astronomy, University of Missouri-St. Louis, St. Louis, MO 63121 (United States)
Publication Date:
OSTI Identifier:
22365261
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 791; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMMONIA; CARBON MONOXIDE; COMETS; COMPARATIVE EVALUATIONS; DATA; DISTANCE; ELEMENT ABUNDANCE; EMISSION; ETHANE; GALAXY NUCLEI; GASES; HYDROCYANIC ACID; INFRARED SPECTROMETERS; METHANE; METHANOL; MOLECULES; ROTATION; SPIN; WATER; WAVELENGTHS