The ESO Diffuse Interstellar Bands Large Exploration Survey (EDIBLES)

I. Project description, survey sample, and quality assessment

¹ Université de Toulouse, UPS-OMP, IRAP, 31028 Toulouse, France
² CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse, France
³ Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
⁴ SETI Institute, 189 Bernardo Avenue, Suite 100, Mountain View, CA 94043, USA
⁵ School of Astronomy, Institute for Research in Fundamental Sciences, 19395-5531 Tehran, Iran
⁶ European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile
⁷ GEPI, Observatoire de Paris, PSL Research University, CNRS, Université Paris-Diderot, Sorbonne Paris Cité, Place Jules Janssen, 92195 Meudon, France
⁸ Instituto de Astrofísica de Canarias (IAC), 38205 La Laguna, Tenerife, Spain
⁹ Universidad de La Laguna, Dpto. Astrofísica, 38206 La Laguna, Tenerife, Spain
¹⁰ School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
¹¹ Royal Astronomical Society, Burlington House, Piccadilly, London W1J 0BQ, UK
¹² AAAS Science International, Clarendon House, Clarendon Road, Cambridge CB2 8FH, UK
¹³ UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, UK
¹⁴ Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, BUS 2401, 3001 Leuven, Belgium
¹⁵ Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
¹⁶ Astrochemistry Laboratory, NASA Goddard Space Flight Center, Code 691, 8800 Greenbelt Road, Greenbelt, MD 20771, USA
¹⁷ Department of Physics, The Catholic University of America, Washington, DC 20064, USA
¹⁸ Lennard-Jones Laboratories, Keele University, ST5 5BG, UK
¹⁹ ESTEC, ESA, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands
²⁰ ICCM, 28049 Madrid, Spain
²¹ Anton Pannekoek Institute for Astronomy, University of Amsterdam, 1090 GE Amsterdam, The Netherlands
²² George Washington University, Washington DC, USA
²³ LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Université Paris 06, 92190 Meudon, France
²⁴ INAF–Osservatorio Astronomico di Cagliari, via della Scienza 5, 09047 Selargius, Italy
²⁵ NASA Ames Research Center, Space Science & Astrobiology Division, Moffett Field, California, USA
²⁶ Kapteyn Institute, University of Groningen, 9712 Groningen, The Netherlands

Received: 31 March 2017
Accepted: 21 July 2017

Abstract

The carriers of the diffuse interstellar bands (DIBs) are largely unidentified molecules ubiquitously present in the interstellar medium (ISM). After decades of study, two strong and possibly three weak near-infrared DIBs have recently been attributed to the C$\begin{array}{c}\mathrm{+}\\ \mathrm{60}\end{array}$ fullerene based on observational and laboratory measurements. There is great promise for the identification of the over 400 other known DIBs, as this result could provide chemical hints towards other possible carriers. In an effort tosystematically study the properties of the DIB carriers, we have initiated a new large-scale observational survey: the ESO Diffuse Interstellar Bands Large Exploration Survey (EDIBLES). The main objective is to build on and extend existing DIB surveys to make a major step forward in characterising the physical and chemical conditions for a statistically significant sample of interstellar lines-of-sight, with the goal to reverse-engineer key molecular properties of the DIB carriers. EDIBLES is a filler Large Programme using the Ultraviolet and Visual Echelle Spectrograph at the Very Large Telescope at Paranal, Chile. It is designed to provide an observationally unbiased view of the presence and behaviour of the DIBs towards early-spectral-type stars whose lines-of-sight probe the diffuse-to-translucent ISM. Such a complete dataset will provide a deep census of the atomic and molecular content, physical conditions, chemical abundances and elemental depletion levels for each sightline. Achieving these goals requires a homogeneous set of high-quality data in terms of resolution (R ~ 70 000–100 000), sensitivity (S/N up to 1000 per resolution element), and spectral coverage (305–1042 nm), as well as a large sample size (100+ sightlines). In this first paper the goals, objectives and methodology of the EDIBLES programme are described and an initial assessment of the data is provided.