Analysis of Low Excitation HDO Transitions Toward the High-Mass Star-forming Regions G34.26+0.15, W51e${}_1$/e${}_2$, and W49N

Abstract

We present observations of the ground state 1${}_{0,1}$-0${}_{0,0}$ rotational transition of HDO at 464.925 GHz and the 1${}_{1,0}$-1${}_{0,1}$ transition at 509.292 GHz toward the three high-mass star forming regions: G34.26+0.15, W49N, and W51e${}_1$/e${}_2$, carried out with the Caltech Submillimeter Observatory. The latter transition is observed for the first time from the ground. The spectra are modeled, together with observations of higher-energy HDO transitions, as well as submillimeter dust continuum fluxes from the literature, using a spherically symmetric radiative transfer model to derive the radial distribution of the HDO abundance in the target sources. The abundance profile is divided into an inner hot core region, with kinetic temperatures higher than 100~K, and a cold outer envelope with lower kinetic temperatures. The derived HDO abundance with respect to H${}_2$ is (0.3-3.7)$\times 10^{-8}$ in the hot inner region ($T>100\mathrm{K}$) and (7.0-10.0)$\times 10^{-11}$ in the cold outer envelope. We also used two H${}_2^{18}$O fundamental transitions to constrain the H${}_2$O abundances in the outer envelopes. The HDO/H${}_2$O ratios in these cold regions are found to be (1.8-3.1)$\times 10^{-3}$ and are consequently higher than in the hot inner regions of these sources.

References in corpus (8)

• Survey of ortho-H2D+(1_{1,0}-1_{1,1}) in dense cloud cores
• Multilayer formation and evaporation of deuterated ices in prestellar and protostellar cores
• A SCUBA imaging survey of ultracompact HII regions: The environments of massive star formation
• The abundances of nitrogen-containing molecules during pre-protostellar collapse
• Warm water deuterium fractionation in IRAS 16293-2422 - The high-resolution ALMA and SMA view
• Millimetre Continuum Observations of Southern Massive Star Formation Regions II. SCUBA observations of cold cores and the dust grain emissivity index $\beta$
• Water deuterium fractionation in the high-mass star-forming region G34.26+0.15 based on Herschel/HIFI data
• Observations of water with Herschel/HIFI toward the high-mass protostar AFGL 2591

Cited by in corpus (4)

• Sulphur-rich cold gas around the hot core precursor G328.2551-0.5321. An APEX unbiased spectral survey of the 2 mm, 1.2 mm, and 0.8 mm atmospheric windows
• SPARKS II.: Complex organic molecules in accretion shocks around a hot core precursor
• SOFIA/GREAT observations of OD and OH rotational lines towards high-mass star forming regions
• Looking for evidence of high-mass star formation at core scale in a massive molecular clump