J/A+A/690/A271 Comets C/2021 A1 and C/2022 E3 (ZTF) spectra (Biver+, 2024)
Chemical composition of comets C/2021 A1 (Leonard) and C/2022 E3 (ZTF) from
radio spectroscopy and the abundance of HCOOH and HNCO in comets.
Biver N., Bockelee-Morvan D., Handzlik B., Sandqvist Aa., Boissier J.,
Drozdovskaya M.N., Moreno R., Crovisier J., Lis D.C., Cordiner M., Milam S.,
Roth N.X., Bonev B.P., Dello Russo N., Vervack R., Opitom C., Kawakita H.
<Astron. Astrophys. 690, A271 (2024)>
=2024A&A...690A.271B 2024A&A...690A.271B (SIMBAD/NED BibCode)
ADC_Keywords: Comets; Radio lines; Spectra, millimetric/submm
Keywords: molecular data - comets: general - radio lines: planetary systems -
submillimeter: planetary systems -
comets: individual: C/2021 A1 (Leonard) -
comets: individual: C/2022 E3 (ZTF)
Abstract:
We present the results of a molecular survey of long period comets
C/2021 A1 (Leonard) and C/2022 E3 (ZTF). Comet C/2021 A1 was observed
with the Institut de radioastronomie millimetrique (IRAM) 30-m radio
telescope in November-December 2021 before perihelion (heliocentric
distance 1.22 to 0.76au) when it was closest to the Earth (~=0.24au).
We observed C/2022 E3 in January-February 2023 with the Odin 1-m space
telescope and IRAM 30-m, shortly after its perihelion at 1.11au from
the Sun, and when it was closest to the Earth (~=0.30au). Snapshots
were obtained during 12-16 November 2021 period for comet C/2021 A1.
Spectral surveys were undertaken over the 8-13 December 2021 period
for comet C/2021 A1 (8GHz bandwidth at 3mm, 16GHz at 2mm, and 61GHz in
the 1mm window) and over the 3-7 February 2023 period for comet C/2022
E3 (2GHz at 2mm and 61GHz at 1mm). We report detections of 14
molecular species (HCN, HNC, CH3CN, HNCO, NH2CHO, CH3OH, H2CO,
HCOOH, CH3CHO, H2S, CS, OCS, C2H5OH and aGg'-(CH2OH)2) in
both comets. In addition, HC3N, and CH2OHCHO were marginally
detected in C/2021 A1, and CO and H2O (with Odin) were detected in
C/2022 E3. The spatial distribution of several species (HCN, HNC, CS,
H2CO, HNCO, HCOOH, NH2CHO, and CH3CHO) is investigated.
Significant upper limits on the abundances of other molecules and
isotopic ratios are also presented. The activity of comet C/2021 A1
did not vary significantly between 13 November and 13 December 2021,
when observations stopped, just before it started to exhibit major
outbursts seen in the visible and from observations of the OH radical.
Short-term variability in the outgassing of comet C/2022 E3 of the
order of ±20% is present and possibly linked to its 8h rotation
period. Both comets exhibit rather low abundances relative to water
for volatile species such as CO (<2%) and H2S (0.15%). Methanol is
also rather depleted in comet C/2021 A1 (0.9%). Following their
revised photo-destruction rates, HNCO and HCOOH abundances in comets
observed at millimetre wavelengths have been reevaluated. Both
molecules are relatively enriched in these two comets (∼0.2% relative
to water). Since the combined abundance of these two acids (0.1 to 1%)
is close to that of ammonia in comets, we cannot exclude that these
species could be produced by the dissociation of ammonium formate and
ammonium cyanate if present in comets.
Description:
Individual, time averaged, IRAM 30m and Odin spectra as presented in
Figs. 2, 6, 11, A.3 and A.6, obtained with the ACS, FTS or VESPA,
autocorrelators. The full frequency range FTS spectra presented in
zenodo (https://doi.org/10.5281/zenodo.13341404) are also provided.
Spectra presented in Figs. 7, 8, 9, 10, A.1, A.2, A.4 and A.5 are
extracted from these spectra.
17 spectra in the H2O map fits file. One fits file per spectrum for
others. fits output are produced from class.
(http://www.iram.fr/IRAMFR/GILDAS/).
objects:
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Code Name Elem q e i H1
d AU deg mag
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C/2021 A1 Leonard 2459600.5 0.6152575 1.0000225 132.686329 10.15
C/2022 E3 ZTF 2459960.5 1.1122535 1.0003023 109.168164 7.16
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 163 34 List of fits spectra
fits/* . 34 Individual fits spectra
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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- 25 I6 --- Nx Number of pixels along X-axis
27- 28 I2 --- Ny ? Number of spectra
30- 52 A23 "datime" Obs.date Observation date
54- 65 E12.6 Hz bFREQ Lower value of frequency interval
67- 77 E11.6 Hz BFREQ Upper value of frequency interval
79- 86 F8.1 Hz dFREQ Frequency resolution
88- 91 I4 Kibyte size Size of FITS file
93-104 A12 --- FileName Name of FITS file, in subdirectory fits
106-163 A58 --- Title Title of the FITS file
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Acknowledgements:
Nicolas Biver, Nicolas.Biver(at)obspm.fr
(End) Patricia Vannier [CDS] 26-Aug-2024