TY - JOUR
T1 - Thermal infrared imaging spectroscopy of Shoemaker-Levy 9 impact sites
T2 - Temperature and HCN retrievals
AU - Bézard, Bruno
AU - Griffith, Caitlin A.
AU - Kelly, Douglas M.
AU - Lacy, John H.
AU - Greathouse, Thomas
AU - Orton, Glenn
N1 - Funding Information:
D.M.K. and J.H.L. were supported by NSF Grant AST-9020292 and USAF Contract F19628-93-K-0011. C.G. was supported in part from the NSF Young Investigator Award and from the NSF/NASA/SL9 Program. G.S.O. acknowledges support from the NASA office of Space Science, Planetary Astronomy and Planetary Atmospheres programs. We are grateful to the staff and management of the NASA/Infrared Telescope Facility for their support. We thank E. Lellouch, A. Marten, and K. Zahnle for enlightening discussions.
Funding Information:
1Visiting astronomer at the Infrared Telescope Facility which is operated by the University of Hawaii under contract with the National Aeronautics and Space Administration.
PY - 1997/1
Y1 - 1997/1
N2 - We present high-resolution 8-14 μm observations of Shoemaker-Levy 9 sites conducted on July 20, 30, and 31 1994 UT at the NASA Infrared Telescope Facility. Stratospheric heating was detected from strong enhancements of methane emission near 8.1 μm over areas at least 15,000 km wide around the K site observed 23 hr after impact and around the L site 11 hr after impact. The intensity distribution between strong and weaker CH4lines implies that the stratospheric heating was primarily confined to pressures less than 500 μbar. The L site temperature increased by 80 ± 10 K at 5 μbar, but did not exceed 20 K around 1 mbar or 10 K around 10 mbar. The older K site was still 30 ± 5 K warmer than the surroundings at the 10-μbar level. The excess thermal energy stored in the upper jovian stratosphere was 3+3-1.5× 1026erg over the L site, and 2+2-1× 1026erg over the K site at the time of the observations. Comparison with numerical simulations indicates that a large fraction (<20%) of the kinetic energy of the L plume was transferred to the jovian atmosphere and not immediately radiated away. Acetylene line emission near 13.4 μm was enhanced over an area ~18,000 km wide centered on the E site 2.6 days after impact. Radiative transfer models of this emission indicate temperatures 37 ± 7 K higher than nominal around 3 μbar. No such enhancement was seen in CH4spectral images, implying that the temperature perturbation did not significantly extend below the ~20-μbar level. The H site observed simultaneously was 12 ± 5 K warmer than the surroundings 1.4 day after impact. C2H2lines were still slightly more intense over the K + W and Q1 sites on July 30 and 31, 8 to 10 days after impact. These observations can be interpreted either by temperature differences of about 13 and 10 K respectively in the 3-μbar region, or by an increase in the C2H2column density of 2.5-5 × 1017molecule cm-2. Emission from hydrogen cyanide lines around 13.4 μm was detected over all sites observed. The mass of HCN is about 2 × 1012g for the biggest plumes (K, L, G), 0.95 ± 0.5 × 1012g over the E site, and 0.45 ± 0.2 × 1012g over the H site. The total mass of HCN produced by all fragments is estimated to be 1.1 ± 0.4 × 1013g. A consistent interpretation of the different pieces of information available suggests that the H $cl10$plume was richer in dust than the E or A plume.
AB - We present high-resolution 8-14 μm observations of Shoemaker-Levy 9 sites conducted on July 20, 30, and 31 1994 UT at the NASA Infrared Telescope Facility. Stratospheric heating was detected from strong enhancements of methane emission near 8.1 μm over areas at least 15,000 km wide around the K site observed 23 hr after impact and around the L site 11 hr after impact. The intensity distribution between strong and weaker CH4lines implies that the stratospheric heating was primarily confined to pressures less than 500 μbar. The L site temperature increased by 80 ± 10 K at 5 μbar, but did not exceed 20 K around 1 mbar or 10 K around 10 mbar. The older K site was still 30 ± 5 K warmer than the surroundings at the 10-μbar level. The excess thermal energy stored in the upper jovian stratosphere was 3+3-1.5× 1026erg over the L site, and 2+2-1× 1026erg over the K site at the time of the observations. Comparison with numerical simulations indicates that a large fraction (<20%) of the kinetic energy of the L plume was transferred to the jovian atmosphere and not immediately radiated away. Acetylene line emission near 13.4 μm was enhanced over an area ~18,000 km wide centered on the E site 2.6 days after impact. Radiative transfer models of this emission indicate temperatures 37 ± 7 K higher than nominal around 3 μbar. No such enhancement was seen in CH4spectral images, implying that the temperature perturbation did not significantly extend below the ~20-μbar level. The H site observed simultaneously was 12 ± 5 K warmer than the surroundings 1.4 day after impact. C2H2lines were still slightly more intense over the K + W and Q1 sites on July 30 and 31, 8 to 10 days after impact. These observations can be interpreted either by temperature differences of about 13 and 10 K respectively in the 3-μbar region, or by an increase in the C2H2column density of 2.5-5 × 1017molecule cm-2. Emission from hydrogen cyanide lines around 13.4 μm was detected over all sites observed. The mass of HCN is about 2 × 1012g for the biggest plumes (K, L, G), 0.95 ± 0.5 × 1012g over the E site, and 0.45 ± 0.2 × 1012g over the H site. The total mass of HCN produced by all fragments is estimated to be 1.1 ± 0.4 × 1013g. A consistent interpretation of the different pieces of information available suggests that the H $cl10$plume was richer in dust than the E or A plume.
UR - https://www.scopus.com/pages/publications/0030639976
UR - https://www.scopus.com/pages/publications/0030639976#tab=citedBy
U2 - 10.1006/icar.1996.5610
DO - 10.1006/icar.1996.5610
M3 - Article
AN - SCOPUS:0030639976
SN - 0019-1035
VL - 125
SP - 94
EP - 120
JO - Icarus
JF - Icarus
IS - 1
ER -