TY - JOUR
T1 - 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
AU - Biver, N.
AU - Bockelée-Morvan, D.
AU - Handzlik, B.
AU - Sandqvist, Aa
AU - Boissier, J.
AU - Drozdovskaya, M. N.
AU - Moreno, R.
AU - Crovisier, J.
AU - Lis, D. C.
AU - Cordiner, M.
AU - Milam, S.
AU - Roth, N. X.
AU - Bonev, B. P.
AU - Dello Russo, N.
AU - Vervack, R.
AU - Opitom, C.
AU - Kawakita, H.
N1 - Publisher Copyright:
© 2024 EDP Sciences. All rights reserved.
PY - 2024/10/11
Y1 - 2024/10/11
N2 - 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 813 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 37 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 (0.11%) 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.
AB - 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 813 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 37 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 (0.11%) 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.
KW - Comets: general
KW - Comets: individual: C/2021 A1 (Leonard)
KW - Comets: individual: C/2022 E3 (ZTF)
KW - Molecular data
KW - Radio lines: planetary systems
KW - Submillimeter: planetary systems
UR - http://www.scopus.com/inward/record.url?scp=85206991441&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/202450921
DO - 10.1051/0004-6361/202450921
M3 - Article
AN - SCOPUS:85206991441
SN - 0004-6361
VL - 690
SP - 1
EP - 29
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A271
ER -