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.
@article{arxiv.1709.03982,
title = {Mapping diffuse interstellar bands in the local ISM on small scales via MUSE 3D spectroscopy},
author = {Martin Wendt and Tim-Oliver Husser and Sebastian Kamann and Ana Monreal-Ibero and Philipp Richter and Jarle Brinchmann and Stefan Dreizler and Peter M. Weilbacher and Lutz Wisotzki},
journal= {arXiv preprint arXiv:1709.03982},
year = {2017}
}
Comments
16 pages, 17 figures, accepted for publication in Astronomy and Astrophysics;