Mapping diffuse interstellar bands in the local ISM on small scales via MUSE 3D spectroscopy

TL;DR

This study uses MUSE 3D spectroscopy to map diffuse interstellar bands and neutral species in the local ISM on milliparsec scales, revealing small-scale variations and demonstrating MUSE's capabilities for detailed ISM observations.

Contribution

It introduces a novel method of mapping the local ISM on very small scales using MUSE, providing new insights into the structure of diffuse interstellar bands and neutral species.

Findings

Detected small-scale variations in DIBs and neutral species within the Local Bubble

Verified MUSE's effectiveness for high-resolution ISM mapping

Probed multiple sight lines through a single physical absorber

Abstract

We map the interstellar medium (ISM) including the diffuse interstellar bands (DIBs) in absorption toward the globular cluster NGC 6397 using VLT/MUSE. This pilot study demonstrates the power of MUSE for mapping the local ISM on very small scales which provides a new window for ISM observations. Assuming the absorbers are located at the rim of the Local Bubble we trace small-scale variations in NaI and KI as well as in several DIBs structures on the order of mpc (milliparsec, a few thousand AU). The sightlines defined by binned stellar spectra are separated by only a few arcseconds and we probe the absorption within a physically connected region. This analysis utilized the fitting residuals of individual stellar spectra of NGC 6397 member stars and analyzed lines from neutral species and several DIBs in Voronoi-binned composite spectra with high signal-to-noise ratio (S/N). We verify the suitability of the MUSE 3D spectrograph for such measurements and gain new insights by probing a single physical absorber with multiple sight lines.