Codella, C;
Viti, S;
Lefloch, B;
Holdship, J;
Bachiller, R;
Bianchi, E;
Ceccarelli, C;
... Tafalla, M; + view all
(2018)
Nitrogen oxide in protostellar envelopes and shocks: the ASAI survey.
Monthly Notices of the Royal Astronomical Society SOCIETY
, 474
(4)
pp. 5694-5703.
10.1093/mnras/stx3196.
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Abstract
The high sensitivity of the IRAM 30-m Astrochemical Surveys At IRAM (ASAI) unbiased spectral survey in the mm window allows us to detect NO emission towards both the Class I object SVS13-A and the protostellar outflow shock L1157-B1. We detect the hyperfine components of the 2Π1/2J = 3/2 → 1/2 (at 151 GHz) and the 2Π1/2J = 5/2 → 3/2 (at 250 GHz) spectral pattern. The two objects show different NO profiles: (i) SVS13-A emits through narrow (1.5 km s−1) lines at the systemic velocity, while (ii) L1157-B1 shows broad (∼5 km s−1) blueshifted emission. For SVS13-A, the analysis leads to Tex ≥ 4 K, N(NO) ≤ 3 × 1015 cm−2, and indicates the association of NO with the protostellar envelope. In L1157-B1, NO is tracing the extended outflow cavity: Tex ≃ 4–5 K, and N(NO) = 5.5 ± 1.5 × 1015 cm−2. Using C18O, 13C18O, C17O, and 13C17O ASAI observations, we derive an NO fractional abundance less than ∼10−7 for the SVS13-A envelope, in agreement with previous measurements towards extended photodissociation regions (PDRs) and prestellar objects. Conversely, a definite X(NO) enhancement is measured towards L1157-B1, ∼6 × 10−6, showing that the NO production increases in shocks. The public code UCLCHEM was used to interpret the NO observations, confirming that the abundance observed in SVS13-A can be attained in an envelope with a gas density of 105 cm−3 and a kinetic temperature of 40 K. The NO abundance in L1157-B1 is reproduced with pre-shock densities of 105 cm−3 subjected to a ∼45 km s−1 shock.
| Type: | Article |
|---|---|
| Title: | Nitrogen oxide in protostellar envelopes and shocks: the ASAI survey |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stx3196 |
| Publisher version: | http://doi.org/10.1093/mnras/stx3196 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | stars: formation, ISM: abundances, ISM: jets and outflows, ISM: molecules |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10045358 |
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