Oscillator strengths of the C2 A(1)Pi(mu)-X(1)Sigma(g+) Phillips system

We report the first detection of C 2 A 1 Π u -X 1 Σ + g (0,0) and CN A 2 Π u -X 2 Σ + (0,0) absorption bands in the interstellar medium. The detection was made using the near-infrared (0.91-1.35 µm) high-resolution (R = 20, 000 and 68,000) spectra of Cygnus OB2 No. 12 collected with the WINERED spectrograph mounted on the 1.3 m Araki telescope. The A-X (1,0) bands of C 2 and CN were detected simultaneously. These near-infrared bands have larger oscillator strengths, compared with the A-X (2,0) bands of C 2 and CN in the optical. In the spectrum of the C 2 (0,0) band with R = 68, 000, three velocity components in the line of sight could be resolved and the lines were detected up to high rotational levels (J ∼ 20). By analyzing the rotational distribution of C 2 , we could estimate the kinetic temperature and gas density of the clouds with high accuracy. Furthermore, we marginally detected weak lines of 12 C 13 C for the first time in the interstellar medium. Assuming that the rotational distribution and the oscillator strengths of the relevant transitions of 12 C 2 and 12 C 13 C are the same, the carbon isotope ratio was estimated to be 12 C/ 13 C = 50-100, which is consistent with the ratio in the local interstellar medium. We also calculated the oscillator strength ratio of the C 2 (0,0) and (1,0) bands from the observed band strengths. Unfortunately, our result could not discern theoretical and experimental results because of the uncertainties. High-resolution data to resolve the velocity components will be necessary for both bands in order to put stronger constraints on the oscillator strength ratios.

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“…The ratios were compared with the experimental results (Davis, et al 1984;Bauer, et al 1985) and cal-…”

Section: Oscillator Strengthsmentioning

confidence: 99%

First Detection of A–X (0,0) Bands of Interstellar C₂ and CN

Kawakita

Kobayashi

Takenaka

et al. 2019

ApJ

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“…In this way the spectrum of the Sun itself was removed and in effect produced a true continuum. Figure 8 shows how this works for C 2 (Davis et al 1984).…”

Section: Research Programmentioning

confidence: 99%

Laboratory spectroscopy of astrophysically interesting molecules

Davis

1987

PASP

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A systematic program on the laboratory analyses of selected molecular spectra, suggested by Charlotte M. Sitterly in 1956 and started in 1958 by Francis A. Jenkins and John G. Phillips, continues to the present day. The program has included tabulations of molecular spectra, analyses, calculations of molecular parameters, measurements of radiative lifetimes, and determinations of transition strengths. Work has been completed or is in progress on the spectra of ArH

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“…The lifetimes of rotational lines in the 0-0 band have tended toward 120 ns, with a corresponding band oscillator strength J00 of 0.025 [3][4][5][6]. In the course of our work on comparing the oscillator strengths of the Phillips and Mulliken bands with those of the Swan bands [7], we decided to remeasure lifetimes of rotational levels in the Swan bands. We present here the results in some detail, since they are 25 % smaller than those from previous experiments.…”

Section: Introductionmentioning

confidence: 99%