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http://hdl.handle.net/20.500.12386/27361
Titolo: | Hot and dense water in the inner 25 au of SVS13-A | Autori: | CODELLA, CLAUDIO Ceccarelli, C. Bianchi, E. PODIO, LINDA Bachiller, R. Lefloch, B. Fontani, F. Taquet, V. Testi, L. |
Data pubblicazione: | 2016 | Rivista: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | Numero: | 462 | Fascicolo: | 1 | Da pagina:: | L75 | Abstract: | In the context of the ASAI (Astrochemical Surveys At IRAM) project, we carried out an unbiased spectral survey in the millimetre window towards the well known low-mass Class I source SVS13-A. The high sensitivity reached (3-12 mK) allowed us to detect at least six HDO broad (full width at half-maximum ∼4-5 km s<SUP>-1</SUP>) emission lines with upper level energies up to E<SUB>u</SUB> = 837 K. A non-local thermodynamic equilibrium Large Velocity Gradient (LVG) analysis implies the presence of very hot (150-260 K) and dense (≥3 × 10<SUP>7</SUP> cm<SUP>-3</SUP>) gas inside a small radius (∼25 au) around the star, supporting, for the first time, the occurrence of a hot corino around a Class I protostar. The temperature is higher than expected for water molecules are sublimated from the icy dust mantles (∼100 K). Although we cannot exclude we are observing the effects of shocks and/or winds at such small scales, this could imply that the observed HDO emission is tracing the water abundance jump expected at temperatures ∼220-250 K, when the activation barrier of the gas phase reactions leading to the formation of water can be overcome. We derive X(HDO) ∼ 3 × 10<SUP>-6</SUP>, and a H<SUB>2</SUB>O deuteration ≥1.5 × 10<SUP>-2</SUP>, suggesting that water deuteration does not decrease as the protostar evolves from the Class 0 to the Class I stage. | URI: | http://hdl.handle.net/20.500.12386/27361 | URL: | https://academic.oup.com/mnrasl/article/462/1/L75/2589676 | ISSN: | 0035-8711 | DOI: | 10.1093/mnrasl/slw127 | Bibcode ADS: | 2016MNRAS.462L..75C | Fulltext: | open |
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