Solis

Abstract

Context. Isotopic fractionation is an important tool for investigating the chemical history of our Solar System. In particular, the isotopic fraction of nitrogen (14N/15N) is lower in comets and other pristine Solar System bodies with respect to the value measured for the protosolar nebula, suggesting a local chemical enrichment of 15N during the formation of the Solar System. Therefore, interferometric studies of nitrogen fractionation in Solar System precursors are needed for us to obtain clues about our astrochemical origins. Aims. In this work we have investigated the variation in the 14N/15N ratio in one of the closest analogues of the environment in which the Solar System was born: the protocluster OMC-2 FIR4. We present the first comparison at high angular resolution between HCN and N2H+ using interferometric data. Methods. We analysed observations of the HCN isotopologues H13CN and HC15N in the OMC-2 FIR4 protocluster. Specifically, we observed the transitions H13CN (1−0) and HC15N (1−0) with the NOrthern Extended Millimeter Array (NOEMA) within the context of the IRAM Seeds Of Life In Space (SOLIS) Large Program. We combined our results with analysis of archival data obtained with the Atacama Large Millimeter Array of N2H+ and its 15N isotopologues. Results. Our results show a small regional variation in the 14N/15N ratio for HCN, from ~250 to 500. The ratios in the central regions of FIR4, where the candidate protostars are located, are largely consistent with one another and within that range (~300). They also show little variation from the part of the protocluster known to harbour a high cosmic-ray ionisation rate to the portion with a lower rate. We also found a small variation in the 14N/15N ratio of N2H+ across different regions, from ~200 to ~400. Conclusions. These results suggest that local changes in the physical parameters occurring on the small linear scales probed by our observations in the protocluster do not seem to affect the 14N/15N ratio in either HCN or N2H+ and hence that this is independent of the molecule used. Moreover, the high level of irradiation due to cosmic rays does not affect the N fractionation either.

CHEMOUT: CHEMical complexity in star-forming regions of the OUTer Galaxy

“…Roueff et al 2015;Wirström & Charnley 2018;Loison et al 2019;Hily-Blant et al 2020). However, recent observational works have highlighted the importance of isotope-selective photodissociation of N 2 in explaining the local variation in the 14 N/ 15 N ratios in massive molecular clouds, low-mass Class 0/I objects, IRDCs, and protoplanetary discs (Colzi et al 2019;Bergner et al 2020;Fontani et al 2020Fontani et al , 2021Hily-Blant et al 2019;Evans et al 2022;Spezzano et al 2022), as suggested by chemical models (e.g. Furuya & Aikawa 2018;Visser et al 2018;Lee et al 2021).…”

ALMA Fragmented Source Catalog in Orion (FraSCO). I. Outflow Interaction within an Embedded Cluster in OMC-2/FIR 3, FIR 4, and FIR 5

“…The FIR 4 region (L = 1000 L e ; Crimier et al 2009) is known to be the most bright and centrally concentrated dust condensation within the embedded protocluster (Chini et al 1997;Lis et al 1998;Johnstone & Bally 1999). Previous millimeter and submillimeter interferometric observations have suggested possible star formation activity within the FIR 4 region (Shimajiri et al 2008;Takahashi et al 2008;López-Sepulcre et al 2013;Fontani et al 2017;Osorio et al 2017;Favre et al 2018;Nakamura et al 2019;Tobin et al 2019;Evans et al 2022). Multiwavelength infrared and centimeter observations have also revealed that the region contains several sources, indicating the presence of protostellar candidates (Reipurth et al 1999;Megeath et al 2012;Furlan et al 2016;Osorio et al 2017).…”

“…López-Sepulcre et al (2013) proposed that the FIR 4 region could be a H II region powered by a B3-B4 type young star. The third scenario is that the FIR 4 region is irradiated by an external source but not by flow-3 (Fontani et al 2017;Favre et al 2018;Evans et al 2022). These three scenarios have been mainly examined with regard to (sub)millimeter interferometric observations with a single pointing.…”

“…These three scenarios have been mainly examined with regard to (sub)millimeter interferometric observations with a single pointing. However, some of the observations have an insufficient angular resolution of 1 5-6″ to spatially resolve substructures and shocked gas within the FIR 4 region (Shimajiri et al 2008;López-Sepulcre et al 2013;Favre et al 2018;Evans et al 2022). ALMA 0.87 mm observations by Tobin et al (2019) and ALMA 1.3 mm observations by Tobin et al (2020) have a high-angular resolution of ∼0 25 and can image dust emission and several molecular lines from sources embedded in the FIR 4 region, though their fields of view do not cover the whole FIR 4 region, and therefore cannot be used to investigate each proposed scenario.…”

OMC-2 FIR 4 under the microscope: Shocks, filaments, and a highly collimated jet at 100 au scales

“…Since then, OMC-2 FIR 4 was thoroughly studied with different telescopes and at different wavelengths (e.g. Takahashi et al 2008;Kama et al 2013Kama et al , 2015Furlan et al 2014;López-Sepulcre et al 2017;Evans et al 2022). Its envelope size and luminosity were estimated to be ∼10 4 au and ≤1000 L ⊙ (Crimier et al 2009;Furlan et al 2014).…”