Accurate rest frequencies of submillimeter-wave lines of H2D+ and D2H+

Amano, T.; Hirao, T.

doi:10.1016/j.jms.2005.05.008

Cited by 52 publications

(58 citation statements)

References 35 publications

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“…A backward-wave oscillator (BWO) based submillimeter-wave spectrometer (Amano & Maeda 2000;Amano & Hirao 2005) was used in conjunction with an extended negative glow electrical discharge cell (De Lucia et al 1983). With three BWO oscillators, the frequency range of 280−890 GHz is covered with two frequency gaps, 530−560 GHz and 750−770 GHz.…”

Section: Experimental Procedures and Resultsmentioning

confidence: 99%

Submillimeter-wave spectrum of CH₂D⁺

Amano

2010

A&A

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Aims. Recently a tentative identification of CH 2 D+ in interstellar space has been reported. To facilitate astronomical identifications, laboratory measurements of precise rest frequencies for the rotational lines of CH 2 D + should be carried out. Methods. A submillimeter-wave spectrometer is used for detection of CH 2 D + . The CH 2 D + ion is generated in an extended negative glow discharge operated at liquid nitrogen temperature. The optimum gas mixture is found to be CH 4 (∼3 mTorr), CD 4 (∼1 mTorr), and H 2 (∼2 mTorr) in helium buffer. Results. Four rotational lines have been detected in the frequency range of 280−890 GHz. The measured frequencies agree very well within a MHz with the predictions given by Rösslein et al. from the infrared spectra. Conclusions. Two rotational lines of this ion have been tentatively identified toward Ori IRc2. The rest frequencies obtained here should facilitate identifications and analysis of astronomical spectra.

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Section: Experimental Procedures and Resultsmentioning

confidence: 99%

Submillimeter-wave spectrum of CH₂D⁺

Amano

2010

A&A

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“…Using the Caltech Submillimeter Observatory 10.4 m telescope (CSO), Vastel et al (2004) detected a ∼3.3σ line (in peak) toward the Ophiuchus dense core 16293E (4.4σ in integrated intensity). This detection is the only published one to date, and its low signal-to-noise ratio, as well as the velocity shift between H 2 D + and D 2 H + (0.23 km s −1 after remeasurement of o-H 2 D + and p-D 2 H + frequencies, Amano & Hirao 2005), certainly require a confirmation of the detection by improving the observation sensitivity and frequency calibration precision (which was ∼0.1 km s −1 in the observations of Vastel et al 2004). We present here the first secure detection of D 2 H + toward the prestellar core H-MM1 in L1688, the main molecular cloud in the Ophiuchus star-forming region.…”

Section: Introductionmentioning

confidence: 83%

“…The frequency of this line is 372.421385 GHz (Amano & Hirao 2005). Observations took place on June 29, 2007, under very good weather conditions (precipitable water vapor PWV = 0.24 mm).…”

Section: H 2 D +mentioning

confidence: 99%

Extended emission of D₂H⁺in a prestellar core

Parise

Беллоче

et al. 2010

A&A

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Context. In the past years, the H 2 D + and D 2 H + molecules have gained attention as probes of cold and depleted dense molecular cloud cores. These ions are the basis of molecular deuterium fractionation, a common characteristic observed in star-forming regions. H 2 D + is now routinely observed, but the search for its isotopologue D 2 H + is still difficult because of the high frequency of its ground para transition (692 GHz). Aims. We observed molecular transitions of H 2 D + and D 2 H + in a cold prestellar core to characterize the roots of deuterium chemistry. Methods. Thanks to the sensitive multi-pixel CHAMP + receiver on the APEX telescope where the required excellent weather conditions are met, we not only successfully detect D 2 H + in the H-MM1 prestellar core located in the L1688 cloud, but also obtain information on the spatial extent of its emission. We also detect H 2 D + at 372 GHz in the same source. We analyze these detections using a non-LTE radiative transfer code and a state-of-the-art spin-dependent chemical model.Results. This observation is the first secure detection of D 2 H + in space. The emission is moreover extended over several pixels of the CHAMP + array, i.e. on a scale of at least 40 , corresponding to ∼4800 AU. We derive column densities on the order of 10 12 -10 13 cm −2 for both molecules in the LTE approximation depending on the assumed temperature, and up to two orders of magnitude higher based on a non-LTE analysis. Conclusions. Our modeling suggests that the level of CO depletion must be extremely high (>10, and even >100 if the temperature of the core is around 10 K) at the core center, contradicting CO depletion levels directly measured in other cores. Observation of the H 2 D + spatial distribution and direct measurement of the CO depletion in H-MM1 will be essential to confirm whether present chemical models investigating the basis of deuterium fractionation of molecules need to be revised.

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“…A Gaussian fit to the H 2 D + line gives a LSR velocity of $7.3 km s À1 , but two peaks are clearly visible, with velocities 7.1 and 7.4 km s À1 (van der Tak et al 2005), as also seen in other tracers (Tafalla et al 1998;Caselli et al 2002b). This central position was originally observed by Caselli et al (2003) and studied in detail by van der Tak et al (2005); here we improved the sensitivity and used the new value of the ortho-H 2 D + (1 10 -1 11 ) line frequency, recently measured by Amano & Hirao (2005 velocity of the H 2 D + line of 7:28 AE 0:06 km s À1 . However, it is difficult to believe that the observed line width represents the real line width of the transition, as the expected thermal line width is about 0.25 km s À1 for a kinetic temperature of 7 K, as predicted by dust temperature measurement (Evans et al 2001;Zucconi et al 2001).…”

Section: Observationsmentioning

confidence: 91%

“…The 345 GHz (650 GHz) sidecab receiver with a 50 MHz acousto-optical spectrometer back end was used for all observations with a velocity resolution of 0.06 km s À1 (0.03 km s À1 ), i.e., $1.6 channels. At the observed frequencies of 372.421385(10) GHz for the H 2 D + (1 10 -1 11 ) and 691.660483(20) for the D 2 H + (1 10 -1 01 ) lines (Amano & Hirao 2005), the CSO 10.4 m antenna has a halfpower beamwidth (HPBW ) of about 20 00 and 11 00 , respectively. We mapped the area in H 2 D + around the dust peak position with a grid spacing of 20 00 and used the value at the peak from Caselli et al (2003) and integrated longer.…”

Section: Observationsmentioning

confidence: 99%

The Distribution of Ortho–H₂D⁺(1_1,0–1_1,1) in L1544: Tracing the Deuteration Factory in Prestellar Cores

Vastel

Caselli

Ceccarelli

et al. 2006

ApJ

104

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Prestellar cores are unique laboratories for studying the chemical and physical conditions preceding star formation. We observed the prestellar core L1544 in the fundamental transition of ortho-H 2 D + (1 1,0 -1 1,1 ) at different positions over 100 00 and found a strong correlation between its abundance and the CO depletion factor. We also present a tentative detection of the fundamental transition of para-D 2 H + (1 1,0 -1 0,1 ) at the dust emission peak. Maps in N 2 H + , N 2 D + , HCO + , and DCO + are used and interpreted with the aid of a spherically symmetric chemical model that predicts the column densities and abundances of these species as a function of radius. The correlation between the observed deuterium fractionation of H þ 3 , N 2 H + , and HCO + and the observed integrated CO depletion factor across the core can be reproduced by this chemical model. In addition, a simpler model is used to study the H 2 D + ortho-to-para ratio. We conclude that, in order to reproduce the observed ortho-H 2 D + observations, the grain radius should be larger than 0.3 m.

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Accurate rest frequencies of submillimeter-wave lines of H2D+ and D2H+

Cited by 52 publications

References 35 publications

Submillimeter-wave spectrum of CH₂D⁺

Submillimeter-wave spectrum of CH₂D⁺

Extended emission of D₂H⁺in a prestellar core

The Distribution of Ortho–H₂D⁺(1_1,0–1_1,1) in L1544: Tracing the Deuteration Factory in Prestellar Cores

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Accurate rest frequencies of submillimeter-wave lines of H2D+ and D2H+

Cited by 52 publications

References 35 publications

Submillimeter-wave spectrum of CH2D+

Submillimeter-wave spectrum of CH2D+

Extended emission of D2H+in a prestellar core

The Distribution of Ortho–H2D+(11,0–11,1) in L1544: Tracing the Deuteration Factory in Prestellar Cores

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Product

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Submillimeter-wave spectrum of CH₂D⁺

Submillimeter-wave spectrum of CH₂D⁺

Extended emission of D₂H⁺in a prestellar core

The Distribution of Ortho–H₂D⁺(1_1,0–1_1,1) in L1544: Tracing the Deuteration Factory in Prestellar Cores