Detection of H2D+ in a massive prestellar core in Orion B

Abstract

Aims. The purpose of this study is to examine the prediction that the deuterated H3+ ion, H2D+, can be found exclusively in the coldest regions of molecular cloud cores. This is also a feasibility study for the detection of the ground-state line of ortho-H2D+ at 372 GHz with APEX. Methods. The 1(10)-1(11) transition of H2D+ at 372 GHz was searched towards selected positions in the massive star forming cloud OriB9, in the dark cloud L183, and in the low- to intermediate mass star-forming cloud R CrA. Results. The line was detected in cold, prestellar cores in the regions of OriB9 and L183, but only upper limits were obtained towards other locations which either have elevated temperatures or contain a newly born star. The H2D+ detection towards OriB9 is the first one in a massive star-forming region. The fractional ortho-H2D+ abundances (relative to H2) are estimated to be about 1.0E-10 in two cold cores in OriB9, and 3.0E-10 in the cold core of L183. Conclusions. The H2D+ detection in OriB9 shows that also massive star forming regions contain very cold prestellar cores which probably have reached matured chemical composition characterized, e.g., by a high degree of deuterium fractionation. Besides as a tracer of the interior parts of prestellar cores, H2D+ may therefore be used to put contraints on the timescales related to massive star formation.

5 pages, 1 figure, accepted for publication in Astronomy and Astrophysics

References in corpus (1)

• The importance of the ortho:para H2 ratio for the deuteration of molecules during pre-protostellar collapse

Cited by in corpus (11)

• Survey of ortho-H2D+(1_{1,0}-1_{1,1}) in dense cloud cores
• Chemistry in Disks. IX. Observations and modeling of HCO+ and DCO+ in DM Tau
• Identification of prestellar cores in high-mass star forming clumps via ${\mathrm{H}}_2{\mathrm{D}}^{+}$ observations with ALMA
• Probing the physics of star formation (ProPStar): I. First resolved maps of the electron fraction and cosmic-ray ionization rate in NGC 1333
• The 3D structure of CO depletion in high-mass prestellar regions
• Experimental and theoretical studies of D + H${}_3^{+}$ $\to$ H${}_2$D${}^{+}$ + H
• APEX observations of ortho-H${}_2$D${}^{+}$ towards dense cores in the Orion B9 filament
• Far-Infrared detection of H2D+ toward Sgr B2
• A computed line list for the H2D+ molecular ion
• H${}_2$D${}^{+}$ line emission in Proto-Planetary Disks
• Synthetic observations using POLARIS: an application to simulations of massive prestellar cores