Broadened profiles of Diffuse Interstellar Bands

Abstract

The paper describes profile broadening and peak wavelength variation of diffuse interstellar bands (DIBs) measured for 46 lines of sight, probably caused by physical properties of intervening clouds. Full width at half maximum of four studied diffuse bands (5780, 5797, 6196 and 6614 Å) demonstrate strong variability sometimes doubling the features' width. Despite the high magnitude of the effect, our current analysis is restricted to the strongest diffuse bands because the weaker ones require a much higher S/N ratio. The profile broadening in the studied DIBs moves the profile's centers towards longer wavelengths, probably due to the excitation of higher levels of the P branch of the unknown molecular carrier. Moreover, diffuse bands are broader in clouds with abundantly populated vibrationally excited states of the hydrogen molecules, i.e. DIB's broadening correlates with the rotational temperature estimated on H${}_2$ $\nu$=2 vibrational level. However, objects demonstrating extremely broadened profiles of DIBs are scarce. The extreme peculiarity of DIBs' profiles was detected in Herschel~36. Here we show the gradual growths of the widths of diffuse bands, confirmed in spectra from different instruments.

arXiv comment8 pages, 9 figures

References in corpus (15)

• The SIMBAD astronomical database
• The BOES spectropolarimeter for Zeeman measurements of stellar magnetic fields
• The Apache Point Observatory Catalog of Optical Diffuse Interstellar Bands
• Anomalous Diffuse Interstellar Bands in the Spectrum of Herschel 36. II. Analysis of Radiatively Excited CH+, CH, and DIBs
• 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
• C${}_{60}^{+}$ - looking for the bucky-ball in interstellar space
• Observational Properties of Rotationally Excited Molecular Hydrogen In Translucent Lines of Sight
• Excitation temperature of C2 and broadening of the 6196A diffuse interstellar band
• Centrosymmetric molecules as possible carriers of diffuse interstellar bands
• Dark Dust and single-cloud sightlines in the ISM
• The $\lambda$6614 diffuse interstellar absorption band: evidence for internal excitation of the carrier
• Diffuse bands 9577 and 9633 -- relations to other interstellar features
• Survey of very broad Diffuse Interstellar Bands
• Interstellar H2 toward HD 37903
• Interstellar H2 toward HD 147888

Cited by in corpus (3)

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• On the intrinsic rest wavelengths of diffuse interstellar bands
• Survey of Profile Parameters of the $6196\mathring{A}$ Diffuse Interstellar Band. From Uniform Profiles to Doppler Splitting and Blueshifts