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Träfflista för sökning "WFRF:(Amano H.) srt2:(2015-2019)"

Search: WFRF:(Amano H.) > (2015-2019)

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  • Kawaguchi, K., et al. (author)
  • Detection of HF Toward PKS 1830-211, Search for Interstellar H2F+, and Laboratory Study of H2F+ and H2Cl+ Dissociative Recombination
  • 2016
  • In: Astrophysical Journal. - 1538-4357 .- 0004-637X. ; 822:2, s. Art. no. 115-
  • Journal article (peer-reviewed)abstract
    • We report extragalactic observations of two fluorine-bearing species, hydrogen fluoride (HF) and fluoronium (H2F+), in the z = 0.89 absorber in front of the lensed blazar PKS 1830-211 with the Atacama Large Millimeter/submillimeter Array. HF was detected toward both southwest and northeast images of the blazar, with column densities >3.4 × 1014 cm-2 and 0.18 × 1014 cm-2, respectively. H2F+ was not detected, down to an upper limit (3?) of 8.8 × 1011 cm-2 and an abundance ratio of [H2F+]/[HF] 1/386. We also searched for H2F+ toward the Galactic sources NGC 6334 I and W51C, and toward Galactic center clouds with the Herschel HIFI spectrometer.6 The upper limit on the column density was derived to be 2.5 × 1011 cm-2 in NGC 6334 I, which is 1/68 of that for H2Cl+. In constrast, the ortho transition of H2Cl+ is detected toward PKS 1830-211. To understand the small abundance of interstellar H2F+, we carried out laboratory experiments to determine the rate constants for the ion-electron recombination reaction by infrared time-resolved spectroscopy. The constants determined are ke(209 K) = (1.1 ± 0.3) ×10-7 cm3 s-1 and (0.46 ± 0.05) ×10-7 cm3 s-1 for H2F+ and H2Cl+, respectively. The difference in the dissociative recombination rates between H2F+ and H2Cl+ by a factor ?2 and the cosmic abundance ratio [F]/[Cl] ? 1/6 are not enough to explain the much smaller abundance of H2F+. The difference in the formation mechanism of H2F+ and H2Cl+ in interstellar space would be a major factor in the small abundance of H2F+.
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4.
  • Muller, Sebastien, 1976, et al. (author)
  • Detection of extragalactic CF+ toward PKS 1830-211 Chemical differentiation in the absorbing gas
  • 2016
  • In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 589, s. Art. no. L5-
  • Journal article (peer-reviewed)abstract
    • We report the first extragalactic detection of the fluoromethylidynium ion CF+ in the z = 0.89 absorber toward PKS 1830-211. We estimate an abundance of similar to 3 x 10(-10) relative to H-2 and that similar to 1% of fluorine is captured in CF+. The absorption line profile of CF+ is found to be markedly different from that of other species observed within the same tuning, and is notably anticorrelated with CH3OH. On the other hand, the CF+ profile resembles that of [CI]. Our results are consistent with expected fluorine chemistry and point to chemical differentiation in the column of absorbing gas.
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  • Result 1-4 of 4

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