Issue |
A&A
Volume 690, October 2024
|
|
---|---|---|
Article Number | A271 | |
Number of page(s) | 29 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202450921 | |
Published online | 11 October 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★,★★
1
LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Université, Université Paris-Cité,
5 place Jules Janssen,
92195
Meudon,
France
2
Astronomical Observatory, Jagiellonian University,
ul. Orla 171,
30-244,
Kraków,
Poland
3
Stockholm Observatory, Stockholm University, SCFAB-AlbaNova,
10691
Stockholm,
Sweden
4
IRAM,
300 rue de la Piscine,
38406
Saint Martin d’Hères,
France
5
Physikalish-Meteorologisches Observatorium Davos und Weltstrahlungszentrum (PMOD/WRC)
Dorfstrasse 33,
7260
Davos Dorf,
Switzerland
6
Jet Propulsion Laboratory, California Institute of Technology,
4800 Oak Grove Drive,
Pasadena,
CA
91109,
USA
7
Solar System Exploration Division,
Astrochemistry Laboratory Code 691, NASA-GSFC,
Greenbelt,
MD
20771,
USA
8
Department of Physics, Catholic University of America,
Washington,
DC
20064,
USA
9
Department of Physics, American University,
Washington,
DC,
USA
10
Johns Hopkins University Applied Physics Laboratory,
11100 Johns Hopkins Rd.,
Laurel,
MD
20723,
USA
11
Institute for Astronomy, University of Edinburgh, Royal Observatory,
Edinburgh
EH9 3HJ,
UK
12
Koyama Astronomical Observatory, Kyoto Sangyo University, Motoyama, Kamitamo, Kita,
Kyoto
603-8555,
Japan
★★★ Corresponding author; nicolas.biver@obspm.fr
Received:
30
May
2024
Accepted:
26
July
2024
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 millimétrique (IRAM) 30-m radio telescope in November-December 2021 before perihelion (heliocentric distance 1.22 to 0.76 au) when it was closest to the Earth (≈0.24 au). 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 1.11 au from the Sun, and when it was closest to the Earth (≈0.30 au). 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 (8 GHz bandwidth at 3 mm, 16 GHz at 2 mm, and 61 GHz in the 1 mm window) and over the 3–7 February 2023 period for comet C/2022 E3 (25 GHz at 2 mm and 61 GHz at 1 mm). 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 (0.1–1%) 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.
Key words: molecular data / comets: general / radio lines: planetary systems / submillimeter: planetary systems / comets: individual: C/2021 A1 (Leonard) / comets: individual: C/2022 E3 (ZTF)
Based on observations carried out with the IRAM-30m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).
Odin is a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes), the Centre National d’Études Spatiales (CNES, France), and the European Space Agency (ESA). The Swedish Space Corporation, today OHB Sweden, is the prime contractor, also responsible for Odin operations.
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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