A search for fine structure inside high resolution profiles of weak diffuse interstellar bands

Słyk, K.; Галазутдинов, Г. А.; Мусаев, Ф. А.; Bondar, A.; Schmidt, M.; Krełowski, J.

doi:10.1051/0004-6361:20052653

Cited by 9 publications

(6 citation statements)

References 27 publications

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“…8. Its profile has been described by Słyk et al (2006) but no substructures have been found in the relatively low resolution. In the HARPS spectrum of HD 147165, the substructures are too weak to be traced with certainty.…”

Section: Resultsmentioning

confidence: 99%

Fine structure in the profiles of strong diffuse interstellar bands

Галазутдинов

Curto

Krełowski

2008

Monthly Notices RAS

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High‐resolution echelle spectra of five reddened OB stars are used to analyse details of the profiles of diffuse interstellar bands (DIBs) at 4726, 4735, 5418, 5850, 6196, 6376, 6379 Å together with the well studied 5797, 5780 and 6614 ones. All targets do not show Doppler splitting in the interstellar CH 4300 band with the applied resolving power R= 115 000. The profiles of DIBs differ from object to object except 5418 which looks invariant in our sample: the DIB is a good candidate for further study of possible isotopic effect. We also found that the width of bands at 5797 and 6614 Å probably is more sensitive to the temperature (and density) effects than that of other DIBs in the sample, though almost all diffuse bands are narrowest in most ζ‐type object (HD 179406) of the sample. On the other hand, it can be just peculiar effect as in a case of unusual line of sight HD 147889 which demonstrates very broad 5780 and 6614 Å diffuse bands what hardly can be explained by temperature effects.

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Section: Resultsmentioning

confidence: 99%

Fine structure in the profiles of strong diffuse interstellar bands

Галазутдинов

Curto

Krełowski

2008

Monthly Notices RAS

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“…For example, visual inspection of the stellar He II 5876 Å line in Fig. 1 shows that HD 149757 and HD 185418 are fast rotators while HD 23180, HD 24398, HD 203532, and HD 170740 have narrower photospheric lines; in these latter cases, we checked even more carefully for the presence of narrow stellar lines in the DIB spectral regions that could mimic DIBs or DIB sub-structures (see the cases of 4727, 4963, 5541, 5546, 5762, 6729; Table 3 from Słyk et al 2006). In the case of the 4734, 5170, 5175, and 6729 Å DIBs, we found that the continuum is contaminated by stellar lines that fall just outside the DIB and, as shown in Figs.…”

Section: Extraction Of Individual C 2 -Dibsmentioning

confidence: 99%

“…Most of the strong and narrow optical DIBs have been found to have asymmetric profiles, and in the case of the strongest ones such as DIBs 5797 and 6614 Å (Sarre et al 1995;Ehrenfreund & Foing 1996;Galazutdinov et al 2002), 5850, 6234, and 6270 Å (e.g., Krełowski & Schmidt 1997;Galazutdinov et al 2002), 6376, 6379, and 6196 Å (Walker et al 2001), sub-structures have been clearly identified which may be consistent with unresolved rotational branch structures associated with electronic transitions of gas-phase molecules. Profiles of several C 2 -DIBs and some other weak DIBs have been examined also by Galazutdinov et al (2002) and Słyk et al (2006). Asymmetries were found, but in the case of the weak C 2 -DIBs these were only seen for the 4963, 5418, 5512, 5541, and 5546 Å bands.…”

Section: Introductionmentioning

confidence: 99%

The EDIBLES survey

Elyajouri

Lallement

Cox

et al. 2018

A&A

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Context. An unambiguous identification of the carriers of the diffuse interstellar bands (DIBs) would provide important clues to the life cycle of interstellar matter. The so-called C2-DIBs are a class of very weak bands that fall in the blue part of the optical spectrum and are associated with high column densities of the C2 molecule. DIB profile structures constrain potential molecular carriers, but their measurement requires high signal-to-noise, high-resolution spectra and the use of sightlines without Doppler splitting, as typical for a single-cloud situation. Aims. Spectra from the ESO Diffuse Interstellar Bands Large Exploration Survey (EDIBLES) conducted at the Very Large Telescope (ESO/Paranal) were explored to identify single-cloud and high C2 column sightlines, extract the corresponding C2-DIBs and study their strengths and profiles, and to investigate in detail any sub-structures. Methods. The target selection was made based on profile-fitting of the 3303 and 5895 Å Na I doublets and the detection of C2 lines. The C2 (2–0) (8750–8849 Å) Phillips system was fitted using a physical model of the host cloud. C2 column densities, temperatures as well as gas densities were derived for each sightline. Results. Eighteen known C2-DIBs and eight strong non-C2 DIBs were extracted towards eight targets, comprising seven single-cloud and one multi-cloud line-of-sights. Correlational studies revealed a tight association of the former group with the C2 columns, whereas the non-C2 DIBs are primarily correlated with reddening. We report three new weak diffuse band candidates at 4737.5, 5547.4, and 5769.8 Å. We show for the first time that at least 14 C2-DIBs exhibit spectral sub-structures which are consistent with unresolved rotational branches of molecular carriers. The variability of their peak separations among the bands for a given sightline implies that their carriers are different molecules with quite different sizes. We also illustrate how profiles of the same DIB vary among targets and as a function of physical parameters, and provide tables defining the sub-structures to be compared with future models and experimental results.

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“…High-resolution, high-S/N ratio spectra have revealed substructure (and variations in that substructure) in a number of the DIBs (Sarre et al 1995;Kre lowski & Schmidt 1997;Kerr et al 1998;Galazutdinov et al 2002Slyk et al 2006), though on velocity scales much smaller than those discussed later in this paper. Ehrenfreund & Foing (1996) interpreted the structure seen in the commonly observed portions of the λλ5797.1, 6379.2, and 6613.6 DIBs as representing rotational contours of large gas-phase molecules.…”

Section: Introductionmentioning

confidence: 77%

Anomalous Diffuse Interstellar Bands in the Spectrum of Herschel 36. I. Observations of Rotationally Excited CH and CH+ Absorption and Strong, Extended Redward Wings on Several DIBs

Dahlstrom,

York,

Welty

et al. 2013

Preprint

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Anomalously broad diffuse interstellar bands (DIBs) at 5780.5, 5797.1, 6196.0, and 6613.6 Å are found in absorption along the line of sight to Herschel 36, the star illuminating the bright Hourglass region of the H II region Messier 8. Interstellar absorption from excited CH + in the J = 1 level and from excited CH in the J = 3/2 level is also seen. To our knowledge, neither those excited molecular lines nor such strongly extended DIBs have previously been seen in absorption from interstellar gas. These unusual features appear to arise in a small region near Herschel 36 which contains most of the neutral interstellar material in the sight line. The CH + and CH in that region are radiatively excited by strong far-IR radiation from the adjacent infrared source Her 36 SE. Similarly, the broadening of the DIBs toward Herschel 36 may be due to radiative pumping of closely spaced high-J rotational levels of relatively small, polar carrier molecules. If this picture of excited rotational states for the DIB carriers is correct and applicable to most DIBs, the 2.7 degree cosmic microwave background may set the minimum widths (about 0.35 Å) of known DIBs, with molecular processes and/or local radiation fields producing the larger widths found for the broader DIBs. Despite the intense local UV radiation field within the cluster NGC 6530, no previously undetected DIBs stronger than 10 m Å in equivalent width are found in the optical spectrum of Herschel 36, suggesting that neither dissociation nor ionization of the carriers of the

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A search for fine structure inside high resolution profiles of weak diffuse interstellar bands

Cited by 9 publications

References 27 publications

Fine structure in the profiles of strong diffuse interstellar bands

Fine structure in the profiles of strong diffuse interstellar bands

The EDIBLES survey

Anomalous Diffuse Interstellar Bands in the Spectrum of Herschel 36. I. Observations of Rotationally Excited CH and CH+ Absorption and Strong, Extended Redward Wings on Several DIBs

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