Context. The inner regions of the envelopes surrounding young protostars are characterised by a complex chemistry, with prebiotic molecules present on the scales where protoplanetary disks eventually may form. The Atacama Large Millimeter/submillimeter Array (ALMA) provides an unprecedented view of these regions zooming in on Solar System scales of nearby protostars and mapping the emission from rare species. Aims. The goal is to introduce a systematic survey, "Protostellar Interferometric Line Survey (PILS)", of the chemical complexity of one of the nearby astrochemical templates, the Class 0 protostellar binary IRAS 16293−2422, using ALMA, to understand the origin of the complex molecules formed in its vicinity. In addition to presenting the overall survey, the analysis in this paper focuses on new results for the prebiotic molecule glycolaldehyde, its isomers and rarer isotopologues and other related molecules.Methods. An unbiased spectral survey of IRAS 16293−2422 covering the full frequency range from 329 to 363 GHz (0.8 mm) has been obtained with ALMA, in addition to a few targeted observations at 3.0 and 1.3 mm. The data consist of full maps of the protostellar binary system with an angular resolution of 0.5 (60 AU diameter), a spectral resolution of 0.2 km s −1 and a sensitivity of 4-5 mJy beam −1 km s −1 -approximately two orders of magnitude better than any previous studies. Results. More than 10,000 features are detected toward one component in the protostellar binary, corresponding to an average line density of approximately one line per 3 km s −1 . Glycolaldehyde, its isomers, methyl formate and acetic acid, and its reduced alcohol, ethylene glycol, are clearly detected and their emission well-modeled with an excitation temperature of 300 K. For ethylene glycol both lowest state conformers, aGg and gGg , are detected, the latter for the first time in the ISM. The abundance of glycolaldehyde is comparable to or slightly larger than that of ethylene glycol. In comparison to the Galactic Center these two species are over-abundant relative to methanol, possibly an indication of formation of the species at low temperatures in CO-rich ices during the infall of the material toward the central protostar. Both 13 C and deuterated isotopologues of glycolaldehyde are detected, also for the first time ever in the ISM. For the deuterated species a D/H ratio of ≈5% is found with no differences between the deuteration in the different functional groups of glycolaldehyde, in contrast to previous estimates for methanol and recent suggestions of significant equilibration between water and -OH functional groups at high temperatures. Measurements of the 13 C-species lead to a 12 C: 13 C ratio of ≈30, lower than the typical ISM value. This low ratio may reflect an enhancement of 13 CO in the ice due to either ion-molecule reactions in the gas before freeze-out or differences in the temperatures where 12 CO and 13 CO ices sublimate. Conclusions. The results reinforce the importance of low temperature grain surfac...

Context. One of the important questions of astrochemistry is how complex organic molecules, including potential prebiotic species, are formed in the envelopes around embedded protostars. The abundances of minor isotopologues of a molecule, in particular the Dand 13 C-bearing variants, are sensitive to the densities, temperatures and time-scales characteristic of the environment in which they form, and can therefore provide important constraints on the formation routes and conditions of individual species. Aims. The aim of this paper is to systematically survey the deuteration and the 13 C content of a variety of oxygen-bearing complex organic molecules on Solar System scales toward the "B component" of the protostellar binary IRAS 16293-2422. Methods. We use the data from an unbiased molecular line survey of the protostellar binary IRAS 16293−2422 between 329 and 363 GHz from the Atacama Large Millimeter/submillimeter Array (ALMA). The data probe scales of 60 AU (diameter) where most of the organic molecules are expected to have sublimated off dust grains and be present in the gas-phase. The deuterated and 13 Cisotopic species of ketene, acetaldehyde and formic acid, as well as deuterated ethanol, are detected unambiguously for the first time in the interstellar medium. These species are analysed together with the 13 C isotopic species of ethanol, dimethyl ether and methyl formate along with mono-deuterated methanol, dimethyl ether and methyl formate. Results. The complex organic molecules can be divided into two groups with one group, the simpler species, showing a D/H ratio of ≈ 2% and the other, the more complex species, D/H ratios of 4-8%. This division may reflect the formation time of each species in the ices before or during warm-up/infall of material through the protostellar envelope. No significant differences are seen in the deuteration of different functional groups for individual species, possibly a result of the short time-scale for infall through the innermost warm regions where exchange reactions between different species may be taking place. The species show differences in excitation temperatures between 125 K and 300 K. This likely reflects the binding energies/sublimation temperatures of the individual species, in good agreement to what has previously been found for high-mass sources. For dimethyl ether the 12 C/ 13 C ratio is found to be lower by up to a factor of 2 compared to typical ISM values similar to what has previously been inferred for glycolaldehyde. Tentative identifications suggest that the same may apply for 13 C isotopologues of methyl formate and ethanol. If confirmed, this may be a clue to their formation at the late prestellar/early protostellar phases with an enhancement of the available 13 C relative to 12 C related to small differences in binding energies for CO isotopologues or the impact of FUV irradiation by the central protostar.Conclusions. The results point to the importance of ice surface chemistry for the formation of these complex organic molecules at different stag...

Formamide (NH 2 CHO) has previously been detected in several star-forming regions and is thought to be a precursor for different prebiotic molecules. Its formation mechanism is still debated, however. Observations of formamide, related species, and their isopotologues may provide useful clues to the chemical pathways leading to their formation. The Protostellar Interferometric Line Survey (PILS) represents an unbiased, high angular resolution and sensitivity spectral survey of the low-mass protostellar binary IRAS 16293-2422 with the Atacama Large Millimeter/submillimeter Array (ALMA). For the first time, we detect the three singly deuterated forms of NH 2 CHO (NH 2 CDO, cis-and trans-NHDCHO), as well as DNCO towards the component B of this binary source. The images reveal that the different isotopologues are all present in the same region. Based on observations of the 13 C isotopologues of formamide and a standard 12 C/ 13 C ratio, the deuterium fractionation is found to be similar for the three different forms with a value of about 2%. The DNCO/HNCO ratio is also comparable to the D/H ratio of formamide (∼1%). These results are in agreement with the hypothesis that NH 2 CHO and HNCO are chemically related through grain-surface formation.

Comets are considered to be some of the most pristine and unprocessed solar system objects accessible to in-situ exploration. Investigating their molecular and elemental composition takes us on a journey back to the early period of our solar system and possibly even further. In this work, we deduce the bulk abundances of the major volatile species in comet 67P/Churyumov-Gerasimenko, the target of the European Space Agency's Rosetta mission. The basis are measurements obtained with the ROSINA instrument suite on board the Rosetta orbiter during a suitable period of high outgassing near perihelion. The results are combined with both gas and dust composition measurements published in the literature. This provides an integrated inventory of the major elements present in the nucleus of 67P/Churyumov-Gerasimenko. Similar to comet 1P/Halley, which was visited by ESA's Giotto spacecraft in 1986, comet 67P/Churyumov-Gerasimenko also shows near-solar abundances of oxygen and carbon, whereas hydrogen and nitrogen are depleted compared to solar. Still, the degree of devolatilization is lower than that of inner solar system objects, * E-mail: martin.rubin@space.unibe.ch 2 including meteorites and the Earth. This supports the idea that comets are among the most pristine objects in our solar system.

Context. Complex organic molecules are detected in many sources in the warm inner regions of envelopes surrounding deeply embedded protostars. Exactly how these species form remains an open question.Aims. This study aims to constrain the formation of complex organic molecules through comparisons of their abundances towards the Class 0 protostellar binary IRAS 16293-2422. Methods. We utilised observations from the Atacama Large Millimetre/submillimetre Array (ALMA) Protostellar Interferometric Line Survey (PILS) of IRAS 16293-2422. The species identification and the rotational temperature and column density estimation were derived by fitting the extracted spectra towards IRAS 16293-2422 A and IRAS 16293-2422 B with synthetic spectra. The majority of the work in this paper pertains to the analysis of IRAS 16293-2422 A for a comparison with the results from the other binary component, which have already been published. Results. We detect 15 different complex species, as well as 16 isotopologues towards the most luminous companion protostar IRAS 16293-2422 A. Tentative detections of an additional 11 isotopologues are reported. We also searched for and report on the first detections of methoxymethanol (CH 3 OCH 2 OH) and trans-ethyl methyl ether (t-C 2 H 5 OCH 3 ) towards IRAS 16293-2422 B and the follow-up detection of deuterated isotopologues of acetaldehyde (CH 2 DCHO and CH 3 CDO). Twenty-four lines of doubly-deuterated methanol (CHD 2 OH) are also identified. Conclusions. The comparison between the two protostars of the binary system shows significant differences in abundance for some of the species, which are partially correlated to their spatial distribution. The spatial distribution is consistent with the sublimation temperature of the species; those with higher expected sublimation temperatures are located in the most compact region of the hot corino towards IRAS 16293-2422 A. This spatial differentiation is not resolved in IRAS 16293-2422 B and will require observations at a higher angular resolution. In parallel, the list of identified CHD 2 OH lines shows the need of accurate spectroscopic data including their line strength. Article number, page 2 of 31 S. Manigand et al.: Inventory of complex organic molecules towards IRAS 16293-2422 A Notes. (a) e 0 , o 1 and e 1 corresponds to the three first torsional states. The notation of the quantum numbers is directly taken from Mukhopadhyay (2016). (b) This corresponds to the number indicated in the top-right corner of each panel in Figures D.1 and D.2. (c) W is the integrated intensity of the unblended lines, summed over the range [ν 0 − ∆ν FWHM , ν 0 + ∆ν FWHM ], given ∆ν FWHM = ν 0 FWHM c , with FWHM equal to 2.2 and 0.8 km s −1 for IRAS 16293A and B, respectively.