Observations of diffuse interstellar bands attributed to C7-

被引:35
作者
McCall, BJ
York, DG
Oka, T
机构
[1] Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA
[2] Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA
关键词
ISM : molecules; line : identification; methods : laboratory; molecular data;
D O I
10.1086/308453
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Recent advances in laboratory gas-phase spectroscopy of large molecules and their ions permit a direct comparison between the diffuse interstellar bands (DIBs) and proposed carriers. On the basis of gas-phase data, Tulej et al. recently suggested that five A(2)Pi(u) <-- X(2)Pi(g) electronic transitions of the linear carbon-chain anion C-7(-) match with DIBs. We have obtained high-resolution visible spectra of four reddened stars (HD 46711, HD 50064, HD 183143, and Cyg OB2 12) to make a detailed comparison with the C-7(-) laboratory data. Our data show that three of the C-7(-) bands (0(0)(0) at 6270.2 Angstrom, 3(0)(1) at 6064.0 Angstrom, and 1(0)(2)3(0)(1) at 4963.0 Angstrom) are in good agreement with DIBs in wavelength and relative intensity. A fourth band (1(0)(1) at 5612.8 Angstrom) also agrees in intensity but is apparently off by 2 Angstrom in wavelength. All other laboratory bands of C-7(-) are not expected to be detectable in astronomical spectra with the current level of sensitivity. The gas-phase spectrum of C-7(-) agrees with the DIBs better than that of any previously proposed molecule. However, the question of whether C-7(-) is a DIB carrier cannot be definitively answered until (1) better laboratory measurements confirm, refute, or explain the wavelength discrepancy for the 1(0)(1) band and/or (2) better astronomical spectra reveal the presence or absence of other C-7(-) bands.
引用
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页码:329 / 335
页数:7
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