Seeds of Life in Space (SOLIS)

Benedettini, M.; Viti, S.; Codella, C.; Ceccarelli, C.; Neri, R.; López-Sepulcre, A.; Bianchi, E.; Busquet, G.; Caselli, P.; Fontani, F.; Leflóch, B.; Podio, L.; Spezzano, S.; Vastel, C.

doi:10.1051/0004-6361/202039609

Cited by 6 publications

(16 citation statements)

References 53 publications

(79 reference statements)

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“…Our column density determinations for HCN and HNC towards L1157-mm and L1157-B1 are in good agreement with those of Bachiller & Pérez-Gutiérrez (1997). Recently, Benedettini et al (2021) observed the H 13 CN and HC 15 N J=1-0 line emission at 4 ′′ resolution toward L1157-B1 using NOEMA, as part of the Large Program SOLIS. Their radiative transfer modelling of both lines yielded N (H 13 CN) ∼ 7 × 10 12 cm −2 and N (HC 15 N) ∼ 2 × 10 12 cm −2 .…”

Section: Line Excitationsupporting

confidence: 87%

“…Recently, Benedettini et al (2021) have investigated the 14 N/ 15 N fractionation of HCN in the two shocked clumps, B1 and B0, of the L1157 outflow using the NOEMA interferometer at ∼ 3 ′′ resolution, and obtained 14 N/ 15 N= 340 ± 70, in good agreement with our determination (see Table 4). Based on the chemical shock modelling, Benedettini et al (2021) conclude that the rich gas chemistry activated by the passage of the shock does not affect the 14 N/ 15 N ratio with respect to the local ISM value. This conclusion is observationally confirmed by our results.…”

Section: Nitrogensupporting

confidence: 87%

“…These maps indicate that the shocked gas in B0 and B1 emit at a velocity distinct from that of B2. Interestingly, the brightest HCN J=3-2 emission coincides with the apex of the outflow cavities, consistent with the high angular resolution NOEMA images of H 13 CN and HC 15 N (Busquet et al 2017;Benedettini et al 2021).…”

Section: Spatial Distributionsupporting

confidence: 83%

“…The GAIA mission has led to a revision of the distance to L1157 by several groups Dzib et al (2018) and ?, who found (360 ± 32) pc and (340 ± 21) pc, respectively. In this work, we will adopt the value of (352 ± 19) pc derived by Zucker et al (2019), in agreement with Benedettini et al (2021). Gueth, Guilloteau, & Bachiller (1996 have studied at high-angular resolution (≈ 3 ′′ ) the structure and dynamics of the southern lobe of the outflow driven by the protostar L1157-mm from the emission of the CO J=1-0 and SiO J=2-1 lines observed with the IRAM Plateau de Bure interferometer.…”

Section: The Sourcementioning

confidence: 69%

“…The spatial distribution of the HCN emission in the L1157 southern outflow lobe was obtained at ≈ 5 ′′ scale for the first time by Benedettini et al (2007) with the IRAM Plateau de Bure interferometer. The emission of the rare 13 C, D and 15 N isotopologues was investigated a few years later at a few arcsec resolution with the IRAM NOEMA interferometer (Busquet et al 2017;Benedettini et al 2021). In particular, the distribution of DCN was shown to result from a combination of gas-phase chemistry that produces the widespread DCN emission, dominating especially in the head of the bow-shock, and sputtering from grain mantles toward the jet impact region.…”

Section: Introductionmentioning

confidence: 99%

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HCN/HNC chemistry in shocks: a study of L1157-B1 with ASAI

Leflóch

Busquet

Viti

et al. 2021

Monthly Notices of the Royal Astronomical Society

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HCN and its isomer HNC play an important role in molecular cloud chemistry and the formation of more complex molecules. We investigate here the impact of protostellar shocks on the HCN and HNC abundances from high-sensitivity IRAM 30m observations of the prototypical shock region L1157-B1 and the envelope of the associated Class 0 protostar, as a proxy for the pre-shock gas. The isotopologues H12CN, HN12C, H13CN, HN13C, HC15N, H15NC, DCN and DNC were all detected towards both regions. Abundances and excitation conditions were obtained from radiative transfer analysis of molecular line emission under the assumption of Local Thermodynamical Equilibrium. In the pre-shock gas, the abundances of the HCN and HNC isotopologues are similar to those encountered in dark clouds, with a HCN/HNC abundance ratio ≈1 for all isotopologues. A strong D-enrichment (D/H≈0.06) is measured in the pre-shock gas. There is no evidence of 15N fractionation neither in the quiescent nor in the shocked gas. At the passage of the shock, the HCN and HNC abundances increase in the gas phase in different manners so that the HCN/HNC relative abundance ratio increases by a factor 20. The gas-grain chemical and shock model UCLCHEM allows us to reproduce the observed trends for a C-type shock with pre-shock density n(H)= $10^5\,{\rm cm^{-3}}$ and shock velocity $V_s = 40\,{\rm km\,s^{-1}}$. We conclude that the HCN/HNC variations across the shock are mainly caused by the sputtering of the grain mantle material in relation with the history of the grain ices.

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Section: Line Excitationsupporting

confidence: 87%

Section: Nitrogensupporting

confidence: 87%

Section: Spatial Distributionsupporting

confidence: 83%

Section: The Sourcementioning

confidence: 69%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

HCN/HNC chemistry in shocks: a study of L1157-B1 with ASAI

Leflóch

Busquet

Viti

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Solis

Evans

Fontani

Vastel

et al. 2022

A&A

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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.

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Isotopic ratios and fractionation in the local Universe

Viti

2022

EPJ Web of Conferences

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The knowledge of isotopic abundances is important in galaxy evolution studies because isotopes provide diagnostics for the chemical enrichment in galaxies over time. While measurements of isotopes in large sample of stars would be ideal to determine the fossil record of the enrichment history, in practice this is hampered by the need of very high resolution, high signal-to-noise spectroscopic data. A complementary, or alternative, method is to measure isotopic ratios from observations of gas-phase interstellar medium (ISM) isotopic abundances. In this proceedings I shall review the observations of the most abundant fractionated species in nearby galaxies and recent modeling efforts aimed at investigating the physical and chemical conditions that can lead to a large spread of isotopic ratios in external local galaxies.

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Seeds of Life in Space (SOLIS)

Cited by 6 publications

References 53 publications

HCN/HNC chemistry in shocks: a study of L1157-B1 with ASAI

HCN/HNC chemistry in shocks: a study of L1157-B1 with ASAI

Solis

Isotopic ratios and fractionation in the local Universe

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