J/A+A/672/A170 Comet 67P/Churyumov-Gerasimenko radio spectra (Biver+, 2023)
Coma composition of comet 67P/Churyumov-Gerasimenko from radio-wave
spectroscopy.
Biver N., Bockelee-Morvan D., Crovisier J., Sandqvist Aa., Boissier J.,
Lis D.C., Cordiner M., Bonev B.P., Dello Russo N., Moreno R., Milam S.,
Roth N.X., Vervack R., DiSanti M.A.
<Astron. Astrophys. 672, A170 (2023)>
=2023A&A...672A.170B 2023A&A...672A.170B (SIMBAD/NED BibCode)
ADC_Keywords: Comets ; Radio lines ; Spectra, millimetric/submm
Keywords: comets: general - comets: individual: 67P/Churyumov-Gerasimenko -
radio lines: planetary systems -
submillimeter: planetary systems
Abstract:
We present the results of a molecular survey of comet
67P/Churyumov-Gerasimenko undertaken with the Institut de
RadioAstronomie Millimetrique (IRAM) 30-m radio telescope in
November-December 2021, when it had its most favourable apparition in
decades.
Observations at IRAM 30-m during the 12-16 November period covered
8GHz bandwidth at 3mm, 16GHz at 2mm, and 60 GHz in the 1mm window
domain. These were completed by snapshots at 1mm on 12-13 December
and a short observation of the H2O line at 557GHz with the Odin
sub-millimetre observatory on 17.0 November 2021, and with 18-cm
observations of OH with the Nancay radio telescope.
Less sensitive observations obtained at a previous perihelion passage
on 18-22 September 2015 with IRAM and 9-12 November 2015 with Odin are
also presented.
The gas outflow velocity, outgassing pattern, and temperature have
been accurately constrained by the observations. They are perfectly
consistent with those measured in situ with the Rosetta/MIRO
sub-millimetre instrument in 2015. In particular, the asymmetry of the
line is well represented by a jet concentrating three-quarters of the
outgassing in about pi steradians. We derived abundances relative to
water for seven molecules and significant upper limits for
approximately five others.
The retrieved abundances were compared to those measured in situ at
the previous perihelion with Rosetta. While those of HCN, CH3OH, and
HNCO are comparable, 67P is found to be depleted in H2S and
relatively normal in CS (H2S/CS3) in strong contradiction with the
Rosetta/ROSINA mass spectrometer measurement of the H2S/CS2 (∼100)
abundance ratio.
While the formaldehyde total abundance found with IRAM∼30-m when
assuming it to be mostly produced by a distributed source (Haser
parent scale length ∼8000km) is similar to the one derived by
Rosetta/ROSINA, we find that the formaldehyde coming from the nucleus
is one order of magnitude less abundant than measured in situ by
Rosetta/ROSINA.
Description:
Individual, time averaged, IRAM 30m and Odin spectra as presented in
Figs. 3, 4, 5, and 6, obtained with the ACS, FTS or VESPA,
autocorrelators. One fits file per spectrum, fits output are produced
from class. (http://www.iram.fr/IRAMFR/GILDAS/).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 147 13 List of fits spectra
fits/* . 13 Individual fits spectra
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See also:
J/A+A/520/A92 : Global plasma parameter simulation of comet 67P
(Gortsas+, 2011)
J/A+A/527/A113 : 67P/Churyumov-Gerasimenko R-band light curve
(Tubiana+, 2011)
J/A+A/548/A12 : 67P/Churyumov-Gerasimenko R-band light curve (Lowry+, 2012)
J/A+A/647/A119 : Comet 67P/Churyumov-Gerasimenko FUV aurora
(Stephenson+, 2021)
J/MNRAS/462/S138 : Robotic view of 67P perihelion (Snodgrass+, 2016)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 24 I5 --- Nx Number of pixels along X-axis
26- 48 A23 "datime" Obs.date Observation date
50- 61 E12.6 Hz bFREQ Lower value of frequency interval
63- 73 E11.6 Hz BFREQ Upper value of frequency interval
75- 82 F8.1 Hz dFREQ Frequency resolution
84- 85 I2 Kibyte size Size of FITS file
87- 98 A12 --- FileName Name of FITS file, in subdirectory fits
100-147 A48 --- Title Title of the FITS file
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Acknowledgements:
Nicolas Biver, Nicolas.Biver(at)obspm.fr
(End) Patricia Vannier [CDS] 14-Mar-2023