J/A+A/564/L2 CH3OH line parameters in comets ISON and Lovejoy (Agundez+, 2014)
Molecular observations of comets C/2012 S1 (ISON) and C/2013 R1 (Lovejoy):
HNC/HCN ratio and upper limits to PH3.
Agundez M., Biver N., Santos Sanz P., Bockelee-Morvan D., Moreno R.
<Astron. Astrophys. 564, L2 (2014)>
=2014A&A...564L...2A 2014A&A...564L...2A
ADC_Keywords: Comets ; Radio lines
Keywords: comets: general - comets: individual: C/2012 S1 (ISON) -
comets: individual: C/2013 R1 (Lovejoy)
Abstract:
We present molecular observations carried out with the IRAM 30m
telescope at wavelengths around 1.15mm towards the Oort cloud comets
C/2012 S1 (ISON) and C/2013 R1 (Lovejoy) when they were at 0.6 and
1AU, respectively, from the Sun. We detect HCN, HNC, and CH3OH in both
comets, together with the ion HCO+ in comet ISON and a few weak
unidentified lines in comet Lovejoy, one of which could be tentatively
assigned to methylamine (CH3NH2). The monitoring of the HCN J=3-2
line showed a tenfold enhancement in comet ISON on November 14.4 UT
due to an outburst of activity whose exact origin is unknown, although
it could be related to some break up of the nucleus. The set of CH3OH
lines observed was used to derive the kinetic temperature in the coma,
90K in comet ISON and 60K in comet Lovejoy. The HNC/HCN ratios
derived, 0.18 in ISON and 0.05 in Lovejoy, are comparable to those
found in most previous comets and are consistent with an enhancement
of HNC as the comet approaches the Sun. Phosphine (PH3) was also
searched for unsuccessfully in both comets through its fundamental
10-00 transition, and 3 sigma upper limits corresponding to
PH3/H2O ratios 4-10 times above the solar P/O elemental ratio
could be derived.
Description:
Observed line parameters of CH3OH (frequencies, line areas, and line
widths) in comets C/2012 S1 (ISON) at Rh=0.61AU and C/2013 R1
(Lovejoy) at Rh=1.06AU.
object.dat :
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Code Name Elem q e i H1
d AU deg mag
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C/2012 S1 ISON 2456624.5 0.0124515 0.9998938 62.401456 6.11
C/2013 R1 Lovejoy 2456651.5 0.8118182 0.9983297 64.040457 11.66
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 69 27 CH3OH line parameters in comets ISON and Lovejoy
table4.dat 53 3 Unidentified lines in comet Lovejoy
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Trans Rotational transition
20- 27 F8.1 MHz Freq [249420/267403] Frequency of line
30- 34 F5.3 K.km/s T(MB)dvI ? C/2012 S1 (ISON) velocity-integrated main
beam brightness temperature
36- 39 F4.3 K.km/s e_T(MB)dvI ? Error in T(MB)dvI (G1)
42- 44 F3.1 km/s DvI ? C/2012 S1 (ISON) line width
(Full width at half maximum)
46- 47 F2.1 km/s e_DvI ? Error in DvI (G1)
52- 56 F5.3 K.km/s T(MB)dvL ? C/2013 R1 (Lovejoy) velocity-integrated
main beam brightness temperature
58- 61 F4.3 K.km/s e_T(MB)dvL ? Error in T(MB)dvL (G1)
64- 66 F3.1 km/s DvL ? C/2013 R1 (Lovejoy) line width
(Full width at half maximum)
68- 69 F2.1 km/s e_DvL ? Error in DvL (G1)
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 8 F8.1 MHz Freq [251766/264753] Frequency of Unidentified line
10- 14 F5.3 K.km/s T(MB)dv Velocity-integrated main beam brightness
temperature
16- 19 F4.3 K.km/s e_T(MB)dv Error in T(MB)dv
21- 23 F3.1 km/s Dv Line width (Full width at half maximum)
25- 26 F2.1 km/s e_Dv Error in Dv
28- 30 F3.1 --- SNR Line area signal-to-noise ratio
32- 53 A22 --- Note Tentative assignment
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Note (G1): Errors in T(MB)dv and Dv are 1 sigma uncertainties. Additional
error in T(MB)dv due to calibration is estimated to be 10 to 20 %.
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Acknowledgements:
Marcelino Agundez, Marcelino.Agundez(at)obs.u-bordeaux1.fr
(End) Patricia Vannier [CDS] 04-Mar-2014