Diffuse interstellar band at 8620 Å in rave: A new method for detecting the diffuse interstellar band in spectra of cool stars

Journal Article · Sun Dec 01 00:00:00 EST 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/778/2/86· OSTI ID:22341972

Kos, J.; Zwitter, T. ^[1]; Grebel, E. K. ^[2]; Bienayme, O.; Siebert, A. ^[3]; Binney, J. ^[4]; Bland-Hawthorn, J. ^[5]; Freeman, K. C. ^[6]; Gibson, B. K. ^[7]; Gilmore, G.; Kordopatis, G. ^[8]; Navarro, J. F. ^[9]; Parker, Q.; Reid, W. A. ^[10]; Seabroke, G. ^[11]; Siviero, A.; Steinmetz, M. ^[12]; Watson, F. ^[13]; Wyse, R. F. G., ^[14]

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1. Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia)
2. Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstraße 12-14, D-69120 Heidelberg (Germany)
3. Observatorie astronomique de Strasbourg, Université de Strasbourg, 11 rue de l'Université, F-67000 Strasbourg (France)
4. Rudolf Peierls Centre for Theoretical Physics, Keble Road, Oxford OX1 3NP (United Kingdom)
5. Sydney Institute for Astronomy, School of Physics A28, University of Sydney, NSW 2008 (Australia)
6. Research School of Astronomy and Astrophysics, Australian National University, Canberra (Australia)
7. Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE (United Kingdom)
8. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
9. University of Victoria, Victoria, BC V8P 5C2 (Canada)
10. Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109 (Australia)
11. Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT (United Kingdom)
12. Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany)
13. Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia)
14. Johns Hopkins University, Homewood Campus, 3400 North Charles Street, Baltimore, MD 21218 (United States)

Diffuse interstellar bands (DIBs) are usually observed in spectra of hot stars, where interstellar lines are rarely blended with stellar ones. The need for hot stars is a strong limitation in the number of sightlines we can observe and their distribution in the Galaxy, as hot stars are rare and concentrated in the Galactic plane. We are introducing a new method, where interstellar lines can be observed in spectra of cool stars in large spectroscopic surveys. The method is completely automated and does not require prior knowledge of the stellar parameters. The main step is a construction of the stellar spectrum, which is done by finding other observed spectra that lack interstellar features and are otherwise very similar to the spectrum in question. Such spectra are then combined into a single stellar spectrum template, matching the stellar component of the observed spectrum. We demonstrate the performance of this new method on a sample of 482,430 Radial Velocity Experiment survey spectra. However, many spectra have to be combined (48 on average) in order to achieve a signal-to-noise ratio high enough to measure the profile of the DIB at 8620 Å, hence limiting the spatial information about the interstellar medium. We compare its equivalent width with extinction maps and with Bayesian reddening, calculated for individual stars, and provide a linear relation between the equivalent width and reddening. Separately from the introduced method, we calculate equivalent widths of the DIB in spectra of hot stars with known extinction and compare all three linear relations.

• OSTI ID: 22341972
• Journal Information: Astrophysical Journal, Vol. 778, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
COMPARATIVE EVALUATIONS
DISTRIBUTION
DUSTS
GALAXIES
MAPS
MATTER
RADIAL VELOCITY
SIGNAL-TO-NOISE RATIO
SPECTRA
STARS