Probing the Local Bubble with Diffuse Interstellar Bands. I. Project overview and Southern hemisphere survey

Abstract

We have conducted a high signal-to-noise spectroscopic survey of 670 nearby early-type stars, to map Diffuse Interstellar Band (DIB) absorption in and around the Local Bubble. The project started with a Southern hemisphere survey conducted at the European Southern Observatory's New Technology Telescope and has since been extended to an all-sky survey using the Isaac Newton Telescope. In this first paper in the series, we introduce the overall project and present the results from the Southern hemisphere survey. We make available a catalogue of equivalent-width measurements of the DIBs at 5780, 5797, 5850, 6196, 6203, 6270, 6283 \& 6614 Å, the interstellar Na\,{\sc i} D lines at 5890 \& 5896 Å, and the stellar He\,{\sc i} line at 5876 Å. We find that the 5780 Å DIB is relatively strong throughout, as compared to the 5797 Å DIB, but especially within the Local Bubble and at the interface with more neutral medium. The 6203 Å DIB shows a similar behaviour, but with respect to the 6196 Å DIB. Some nearby stars show surprisingly strong DIBs whereas some distant stars show very weak DIBs, indicating small-scale structure within as well as outside the Local Bubble. The sight-lines with non-detections trace the extent of the Local Bubble especially clearly, and show it opening out into the Halo. The Local Bubble has a wall which is in contact with hot gas and/or a harsh interstellar radiation field. That wall is perforated though, causing leakage of radiation and possibly hot gas. On the other hand, compact self-shielded cloudlets are present much closer to the Sun, probably within the Local Bubble itself. As for the carriers of the DIBs, our observations confirm the notion that these are large molecules, whose differences in behaviour are mainly governed by their differing resilience and/or electrical charge, with more subtle differences possibly related to varying excitation.

Accepted for publication in Astronomy & Astrophysics

References in corpus (12)

• A Catalog of Diffuse Interstellar Bands in the Spectrum of HD 204827
• The Diffuse Interstellar Bands: A Major Problem in Astronomical Spectroscopy
• The origin of the 'local' 1/4 keV X-ray flux in both charge exchange and a hot bubble
• The Trouble with the Local Bubble
• Mapping the Interstellar Medium with Near-Infrared Diffuse Interstellar Bands
• Pseudo Three-dimensional Maps of the Diffuse Interstellar Band at 862 nm
• Detailed maps of interstellar clouds in front of omega Centauri: Small-scale structures in the Galactic Disc-Halo interface
• Dusting off the diffuse interstellar bands: DIBs and dust in extragalactic SDSS spectra
• Small-scale structure in the interstellar medium: time-varying interstellar absorption towards κ Velorum
• Mapping atomic and diffuse interstellar band absorption across the Magellanic Clouds and the Milky Way
• Probing the Local Bubble with Diffuse Interstellar Bands. II. The DIB properties in the Northern hemisphere
• Probing the Local Bubble with Diffuse Interstellar Bands. III. The Northern hemisphere data and catalog

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