Diffuse interstellar bands

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Relative strength of diffuse interstellar bands

Diffuse interstellar bands ( English Diffuse Interstellar Bands; DIB ) are absorption bands in the electromagnetic spectra of astronomical objects. These bands are causally assigned to interstellar matter .

Diffuse interstellar bands are detected in the near infrared , in the range of ultraviolet radiation and in the visual. The best-known band is 4430  angstroms with a width ( FWHM ) of a few dozen angstroms, a depth of 15 percent compared to the continuum and an equivalent width of 3 Å. Other strong bands are at 4765, 4880, 5780, 5800, 6180 and 6280 Å. Some bands extend over widths up to 200 Å with very little depth of absorption . The equivalent widths of diffuse interstellar bands are correlated , but not strictly correlated, with the interstellar absorbance .

The diffuse interstellar bands were connected by PW Merill in 1934 with solid particles with a diameter in the order of magnitude of the affected electromagnetic radiation . These are probably dust particles that are composed predominantly of polycyclic aromatic hydrocarbons , Buckminster fullerene and silicates .

Recent research has cast doubt on the paradigm that the diffuse interstellar bands are caused solely by the interstellar medium. When the supernova SN 2012ap erupted, a change in the equivalent widths of the DIB was observed. This phenomenon is known as Variable Diffuse Interstellar Bands. The VDIB, which could probably also be detected in blue giants in the Milky Way , suggest that part of the DIB is created by an interaction between the stellar wind and the interstellar matter.

Individual evidence

  1. ^ Daniel E. Welty: Diffuse Interstellar Bands: How Are They Related to Known Gas-Phase Constituents of the ISM? In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1307.5477v1 .
  2. ↑ Olivier Berné, Giacomo Mulas, Christine Joblin: Detection of the buckminsterfullerene cation (C60 +) in space . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1307.4561v1 .
  3. ^ Charles J. Law et al .: TRES Survey of Variable Diffuse Interstellar Bands . In: Astrophysics. Solar and Stellar Astrophysics . 2017, arxiv : 1706.07801v1 .