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.

We present the results of a molecular survey of comet 67P/Churyumov-Gerasimenko undertaken with the Institut de RadioAstronomie Millimétrique (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 8 GHz bandwidth at 3 mm, 16 GHz at 2 mm, and 60 GHz in the 1 mm window domain. These were completed by snapshots at 1 mm on 12–13 December and a short observation of the H₂O line at 557 GHz with the Odin sub-millimetre observatory on 17.0 November 2021, and with 18-cm observations of OH with the Nançay 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 π 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/CS ≈ 3) 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 ≈8000 km) 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.

Context. The Odin satellite is now into its twentieth year of operation, much surpassing its design life of two years. One of its major astronomical pursuits was the search for and study of water vapor in diverse regions of the Solar System and the Milky Way galaxy. The Herschel space observatory was needed to detect water vapor in external galaxies.

Aims. Our goal is to study the distribution and excitation of water vapor and other molecules in the barred spiral galaxy NGC 1365.

Methods. Herschel has observed the central region of NGC 1365 in two positions, and both its SPIRE and PACS observations are available in the Herschel Science Archive. Herschel PACS images have been produced of the 70 and 160 mu m infrared emission from the whole galaxy, and also of the cold dust distribution as obtained from the ratio of the 160 to 70 mu m images. The Herschel SPIRE observations have been used to produce simultaneously observed maps of the 557 GHz o-H2O, 752 GHz p-H2O, 691 GHz CO(6-5), 1037 GHz CO(9-8), 537 GHz CH, 835 GHz CH', and the 1461 GHz [N IT] lines (efficiently probing the warm ionized medium) in the inner bar and circumnuclear torus region; - however, these observations have no effective velocity resolution. For this reason Odin has recently observed the 557 GHz ortho-H2O ground state line in the central region with high (5 km s(-1)) spectral resolution.

Results. The emission and absorption of H2O at 557 GHz, with a velocity resolution of 5 km s(-1), has been marginally detected in NGC 1365 with Odin. The water vapor is predominantly located in a shocked 15 '' (1.3 kpc) region near some central compact radio sources and hot-spot HIT regions, close to the northeast component of the molecular torus surrounding the nucleus. An analysis of the H2O line intensities and velocities indicates that a shock-region is located here. This is corroborated by a statistical image deconvolution of our SEST CO(3-2) observations, yielding 5 '' resolution, and a study of our Very Large Array HI absorption observations, as well as comparisons with published interferometric CO observations. Additionally, an enticing 20 '' HI ridge is found to extend south-southeast from the nucleus, coinciding in position with the southern edge of an O III outflow cone, emanating from the nucleus. The molecular chemistry of the shocked central region of NGC 1365 is analyzed with special emphasis on the CO, H2O and CH, CH+ results.

Conclusions. The dominating activity near the northeast (NE) torus component may have been triggered by the rapid bar-driven inflow into the circumnuclear torus causing cloud-cloud collisions and shocks, leading to the formation of stellar superclusters and, hence, also to more efficient PDR chemistry, which, here, may also benefit from cosmic ray focusing caused by the observed aligned magnetic field. The very high activity near the NE torus component may reflect the fact that the eastern bar-driven gas inflow into the NE region is much more massive than the corresponding western gas inflow into the southwest region. The H2O and CH+ emissions peak in the NE torus region, but the CO and CH emissions are more evenly distributed across the whole circumnuclear torus. The higher energy CO spectral line energy distribution (SLED) is nicely modeled by a low velocity (10 km s(-1)) shock, which may as well explain the required CH excitation and its high abundance in denser gas. The higher velocity (40 km s(-1)) shock required to model the H2O SLED in the NE torus region, paired with the intense UV radiation from the observed massive young stellar superclusters, may also explain the high abundance of CH+ in this region. The nuclear H I ridge may have been created by the action of outflow-driving X-ray photons colliding with ice-covered dust grains. A precessing nuclear engine, as is suggested by the tilted massive inner gas torus, may be necessary to explain the various nuclear outflows encountered.

Context. The comet Shoemaker-Levy 9 impacted Jupiter in July 1994, leaving its stratosphere with several new species, with water vapor (H₂O) among them.

Aims. With the aid of a photochemical model, H₂O can be used as a dynamical tracer in the Jovian stratosphere. In this paper, we aim to constrain the vertical eddy diffusion (K_zz) at levels where H₂O is present.

Methods. We monitored the H₂O disk-averaged emission at 556.936 GHz with the space telescope between 2002 and 2019, covering nearly two decades. We analyzed the data with a combination of 1D photochemical and radiative transfer models to constrain the vertical eddy diffusion in the stratosphere of Jupiter. Results. Odin observations show us that the emission of H₂O has an almost linear decrease of about 40% between 2002 and 2019. We can only reproduce our time series if we increase the magnitude of K_zz in the pressure range where H₂O diffuses downward from 2002 to 2019, that is, from ~0.2 mbar to ~5 mbar. However, this modified K_zz is incompatible with hydrocarbon observations. We find that even if an allowance is made for the initially large abundances of H₂O and CO at the impact latitudes, the photochemical conversion of H₂O to CO₂ is not sufficient to explain the progressive decline of the H₂O line emission, which is suggestive of additional loss mechanisms.

Conclusions. The K_zz we derived from the Odin observations of H₂O can only be viewed as an upper limit in the ~0.2 mbar to ~5 mbar pressure range. The incompatibility between the interpretations made from H₂O and hydrocarbon observations probably results from 1D modeling limitations. Meridional variability of H₂O, most probably at auroral latitudes, would need to be assessed and compared with that of hydrocarbons to quantify the role of auroral chemistry in the temporal evolution of the H₂O abundance since the SL9 impacts. Modeling the temporal evolution of SL9 species with a 2D model would naturally be the next step in this area of study.

Context. The Odin satellite is now into its sixteenth year of operation, much surpassing its design life of two years. One of the sources which Odin has observed in great detail is the Sgr A complex in the centre of the Milky Way.

Aims. To study the presence of NH3 in the Galactic centre and spiral arms.

Methods. Recently, Odin has made complementary observations of the 572 GHz NH3 line towards the SgrA + 50 km s(-1) cloud and circumnuclear disk (CND).

Results. Significant NH3 emission has been observed in both the + 50 km s(-1) cloud and the CND. Clear NH3 absorption has also been detected in many of the spiral arm features along the line of sight from the Sun to the core of our Galaxy.

Conclusions. The very large velocity width (80 km s 1) of the NH3 emission associated with the shock region in the southwestern part of the CND may suggest a formation / desorption scenario similar to that of gas-phase H2O in shocks / outflows.

The apparition of bright comets C/2012 F6 (Lemmon) and C/2014 Q2 (Lovejoy) in March-April 2013 and January 2015, combined with the improved observational capabilities of submillimeter facilities, offered an opportunity to carry out sensitive compositional and isotopic studies of the volatiles in their coma. We observed comet Lovejoy with the IRAM 30 m telescope between 13 and 26 January 2015, and with the Odin submillimeter space observatory on 29 January-3 February 2015. We detected 22 molecules and several isotopologues. The (H2O)-O-16 and (H2O)-O-18 production rates measured with Odin follow a periodic pattern with a period of 0.94 days and an amplitude of similar to 25%. The inferred isotope ratios in comet Lovejoy are O-16/O-18 = 499 +/- 24 and D/H = 1.4 +/- 0.4 x 10(-4) in water, S-32/S-34 = 24.7 +/- 3.5 in CS, all compatible with terrestrial values. The ratio C-12/C-13 = 109 +/- 14 in HCN is marginally higher than terrestrial and N-14/N-15 = 145 +/- 12 in HCN is half the Earth ratio. Several upper limits for D/H or C-12/C-13 in other molecules are reported. From our observation of HDO in comet C/2014 Q2 (Lovejoy), we report the first D/H ratio in an Oort Cloud comet that is not larger than the terrestrial value. On the other hand, the observation of the same HDO line in the other Oort-cloud comet, C/2012 F6 (Lemmon), suggests a D/H value four times higher. Given the previous measurements of D/H in cometary water, this illustrates that a diversity in the D/H ratio and in the chemical composition, is present even within the same dynamical group of comets, suggesting that current dynamical groups contain comets formed at very different places or times in the early solar system.

The presence of numerous complex organic molecules (COMs; defined as those containing six or more atoms) around protostars shows that star formation is accompanied by an increase of molecular complexity. These COMs may be part of the material from which planetesimals and, ultimately, planets formed. Comets represent some of the oldest and most primitive material in the solar system, including ices, and are thus our best window into the volatile composition of the solar protoplanetary disk. Molecules identified to be present in cometary ices include water, simple hydrocarbons, oxygen, sulfur, and nitrogen-bearing species, as well as a few COMs, such as ethylene glycol and glycine. We report the detection of 21 molecules in comet C/2014 Q2 (Lovejoy), including the first identification of ethyl alcohol (ethanol, C₂H₅OH) and the simplest monosaccharide sugar glycolaldehyde (CH₂OHCHO) in a comet. The abundances of ethanol and glycolaldehyde, respectively 5 and 0.8% relative to methanol (0.12 and 0.02% relative to water), are somewhat higher than the values measured in solar-type protostars. Overall, the high abundance of COMs in cometary ices supports the formation through grain-surface reactions in the solar system protoplanetary disk.

Context: The Herschel Oxygen Project (HOP) is an open time key program, awarded 140 h of observing time to search for molecular oxygen (O-2) in a number of interstellar sources. To date O-2 has definitely been detected in only two sources, namely rho Oph A and Orion, reflecting the extremely low abundance of O-2 in the interstellar medium.

Aims: One of the sources in the HOP program is the + 50 km s(-1) Cloud in the Sgr A Complex in the centre of the Milky Way. Its environment is unique in the Galaxy and this property is investigated to see if it is conducive to the presence of O-2. Methods. The Herschel Heterodyne Instrument for the Far Infrared (HIFI) is used to search for the 487 and 774 GHz emission lines of O-2.

Results: No O-2 emission is detected towards the Sgr A + 50 km s(-1) Cloud, but a number of strong emission lines of methanol (CH3OH) and absorption lines of chloronium (H2Cl+) are observed.

Conclusions: A 3 sigma upper limit for the fractional abundance ratio of [O-2]/[H-2] in the Sgr A + 50 km s(-1) Cloud is found to be X(O-2) <= 5x 10(-8). However, since we can find no other realistic molecular candidate than O-2 itself, we very tentatively suggest that two weak absorption lines at 487.261 and 487.302 GHz may be caused by the 487 GHz line of O-2 in two foreground spiral arm clouds. By considering that the absorption may only be apparent, the estimated upper limit to the O-2 abundance of <=(10-20) x 10(-6) in these foreground clouds is very high, as opposed to the upper limit in the Sgr A + 50 km s(-1) Cloud itself, but similar to what has been reached in recent chemical shock models for Orion. This abundance limit was determined also using Odin non-detection limits, and assumes that O-2 fills the beam. If the absorption is due to a differential Herschel OFF-ON emission, the O-2 fractional abundance may be of the order of approximate to(5-10) x 10 (6). With the assumption of pure absorption by foreground clouds, the unreasonably high abundance of (1.4-2.8) x 10(-4) was obtained. The rotation temperatures for CH3OH-A and CH3OH-E lines in the + 50 km s(-1) Cloud are found to be approximate to 64 and 79 K, respectively, and the fractional abundance of CH3OH is approximately 5 x 10(-7).

Aims. We study the structure and kinematics of the OH-streamer and the +80 km s(-1) cloud and their interactions with the circumnu-clear disk (CND) and with other molecular clouds in the vicinity of the Galactic centre (GC), and we map OH absorption at about 6 '' resolution at R <= 10 pc from the GC, with about 9 km s(-1) of velocity resolution. Methods. The VLA was used to map OH line absorption at the 1665 and 1667 MHz lambda doublet main lines of the (2)Pi(3/2) state towards the Sagittarius A complex. Results. Strong OH absorption was found in the OH-streamer, the southern streamer (SS), the +20, +50, and +80 km s(-1) molecular clouds, the molecular belt, the CND, the expanding molecular ring (EMR), and the high negative velocity gas (HNVG). The OH-streamer was found to comprise three parts, head, mid, and tail, and to interact with the SS/+20, +80 km s(-1) clouds and the CND. Optical depths and column densities divided by excitation temperatures have been calculated for the OH-streamer and the +80 km s(-1) cloud. Conclusions. The OH-streamer, the SS, the +20 and +80 km s(-1) clouds, and the CND are intimately related in position and velocity space. The OH-streamer was found to be a clumpy object stretching in projection from the inner radius of the CND at about 1.8 pc from Sgr A*towards and partly engulfing Sgr A*. As a side result of our data, a possible link between the near side of the EMR and the CND's southwest lobe was found. Additionally, we found OH absorption against all four of the previously known compact H II regions A-D, located east of Sgr A East, indicating their close association with the +50 km s(-1) cloud.

The VLA was used to map OH line absorption at the 1665 and 1667MHz lambda doublet main lines of the ²{Pi}_3/2 state towards the Sagittarius A complex. Strong OH absorption was found in the OH-streamer, the southern streamer (SS), the +20, +50, and +80km/s molecular clouds, the molecular belt, the CND, the expanding molecular ring (EMR), and the high negative velocity gas (HNVG).

Data cubes of VLA observations of the Sgr A complex at 1667- and 1665MHz OH-absorption at 7"x5" angular and 8.8km/s velocity resolution in 63 spectral channels centered at -38km/s (LSR). OH-absorption is defined as "continuum flux minus line flux". The continuum is taken as the average of 1665 and 1667 MHz maps of line free channels. Observations with the VLA in BnA and DnC arrays have been concatenated with AIPS, and data were calibrated and CLEANed with NRAO AIPS standard procedures.

(2 data files).