Deuterated methanol on a solar system scale around the HH212 protostar
Open Access
- 10 October 2017
- journal article
- Published by EDP Sciences in Astronomy & Astrophysics
- Vol. 606, L7
- https://doi.org/10.1051/0004-6361/201731404
Abstract
Context. Deuterium fractionation is a valuable tool for understanding the chemical evolution during the process that leads to the formation of a Sun-like planetary system. Aims. Methanol is thought to be mainly formed during the prestellar phase, and its deuterated form keeps a memory of the conditions at that epoch. The unique combination of high angular resolution and sensitivity provided by ALMA enables us to measure methanol deuteration in the planet formation region around a Class 0 protostar and to understand its origin. Methods. We mapped both the 13CH3OH and CH2DOH distribution in the inner regions (~100 au) of the HH212 system in Orion B. To this end, we used ALMA Cycle 1 and Cycle 4 observations in Band 7 with angular resolution down to ~0.̋15. Results. We detected 6 lines of 13CH3OH and 13 lines of CH2DOH with upper level energies of up to 438 K in temperature units. We derived a rotational temperature of (171 ± 52) K and column densities of 7 × 1016 cm-2 (13CH3OH) and 1 × 1017 cm-2 (CH2DOH), respectively. This yields a D/H ratio of (2.4 ± 0.4) × 10-2, which is lower by an order of magnitude than previously measured values using single-dish telescopes toward protostars located in Perseus. Our findings are consistent with the higher dust temperatures in Orion B with respect to the temperature derived for the Perseus cloud. The emission traces a rotating structure extending up to 45 au from the jet axis, which is elongated by 90 au along the jet axis. So far, the origin of the observed emission appears to be related with the accretion disc. Only higher spatial resolution measurements will be able to distinguish between different possible scenarios, however: disc wind, disc atmosphere, or accretion shocks.Keywords
This publication has 38 references indexed in Scilit:
- Decrease of the organic deuteration during the evolution of Sun-like protostars: the case of SVS13-AMonthly Notices of the Royal Astronomical Society, 2017
- Exploring molecular complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2)Astronomy & Astrophysics, 2016
- The ALMA view of the protostellar system HH212Astronomy & Astrophysics, 2014
- High SiO abundance in the HH212 protostellar jetAstronomy & Astrophysics, 2012
- THE HERSCHEL AND IRAM CHESS SPECTRAL SURVEYS OF THE PROTOSTELLAR SHOCK L1157-B1: FOSSIL DEUTERATIONThe Astrophysical Journal Letters, 2012
- Survey of ortho-H$\mathsf{_{2}}$D$\mathsf{^{+}}$ (1$\mathsf{_{1,0}}$–1$\mathsf{_{1,1}}$) in dense cloud coresAstronomy & Astrophysics, 2008
- PdBI sub-arcsecond study of the SiO microjet in HH212Astronomy & Astrophysics, 2007
- A highly-collimated SiO jet in the HH212 protostellar outflowAstronomy & Astrophysics, 2006
- Theoretical H$_mathsf{2}$CO emission from protostellar envelopesAstronomy & Astrophysics, 2003
- Distribution and Motion of the Water Masers near IRAS 05413−0104The Astrophysical Journal, 1998