Interstellar medium. Pseudo-three-dimensional maps of the diffuse interstellar band at 862 nm

Area of Science:

• Astronomy
• Astrophysics
• Spectroscopy

Background:

• Diffuse interstellar bands (DIBs) are absorption lines observed in stellar spectra since 1922.
• Their origin in the interstellar medium remains a long-standing problem in astronomical spectroscopy.

Purpose of the Study:

• To investigate the spatial distribution of a specific DIB (8620 angstroms) in the local interstellar medium.
• To compare the distribution of this DIB with the distribution of interstellar dust.

Main Methods:

• Utilized nearly 500,000 stellar spectra from the RAVE (Radial Velocity Experiment) survey.
• Generated a pseudo-three-dimensional map of DIB 8620 strength within 3 kiloparsecs of the Sun.
• Constructed an independent spatial distribution map of interstellar dust extinction.

Main Results:

• The spatial distribution of DIB 8620 strength closely follows interstellar dust extinction along the Galactic plane.
• The DIB 8620 carrier exhibits a significantly larger vertical scale height than interstellar dust.
• This suggests distinct spatial properties for DIB carriers compared to dust.

Conclusions:

• The study provides a novel, pseudo-3D map of a DIB in the local interstellar medium.
• The findings indicate that while DIBs and dust share similar distributions in the Galactic plane, their vertical distributions differ.
• This research sets a direction for future studies on the nature and distribution of DIBs.