Integrated spectroscopy of the Herschel Reference Survey
Laboratoire d’Astrophysique de Marseille – LAM, Université d’Aix-Marseille
& CNRS, UMR 7326, 38 rue F.
Marseille Cedex 13,
e-mail: Alessandro.Boselli@oamp.fr; Veronique.Buat@oamp.fr
2 Kavli Institute for Astronomy & Astrophysics, Peking University, 100871 Beijing, PR China
3 European Southern Observatory, Karl-Schwarzschild Str. 2, 85748 Garching bei Muenchen, Germany
4 Universita’ di Milano-Bicocca, piazza della Scienza 3, 20126 Milano, Italy
Accepted: 22 November 2012
We present long-slit integrated spectroscopy of 238 late-type galaxies belonging to the Herschel Reference Survey, a volume-limited sample representative of the nearby universe. This sample has a unique legacy value since it was ideally defined for any statistical study of the multifrequency properties of galaxies spanning a wide range in morphological type and luminosity. The spectroscopic observations cover the spectral range 3600−6900 Å at a resolution R ≃ 1000 and are thus suitable for separating both the underlying absorption from the emission of the Hβ line and the two [Nii] lines from the Hα emission. We measured the fluxes and the equivalent widths of the strongest emission lines ([Oii]λ3727, Hβ, [Oiii]λ4959 and [Oiii]λ5007, [Nii]λ6548, Hα, [Nii]λ6584, [Sii]λ6717, and [Sii]λ6731). We used the data to study the distribution of the equivalent width of all the emission lines, of the Balmer decrement C(Hβ), and of the observed underlying Balmer absorption under Hβ (EW Hβabs) in this sample. Combining these new spectroscopic data with those available at other frequencies, we also study the dependence of C(Hβ) and EW Hβabs on morphological type, stellar mass, stellar surface density, star formation rate, birthrate parameter, and metallicity in galaxies belonging to different environments (fields vs. Virgo cluster). The distribution of the equivalent width of all the emission lines, of C(Hβ) (or equivalently of A(Hα)), and of EW Hβabs are systematically different in cluster and field galaxies. The Balmer decrement increases with the stellar mass, stellar surface density, metallicity, and star formation rate of the observed galaxies, while it is unexpectedly almost independent of the column density of the atomic and molecular gas. The dependence of C(Hβ) on stellar mass is steeper than previously found in other works. The underlying Balmer absorption does not significantly change with any of these physical parameters.
Key words: galaxies: spiral / galaxies: ISM / dust, extinction
Based on observations collected at the Observatoire de Haute Provence (OHP) (France), operated by the CNRS.
Tables 7−11 and Fig. 19 are available in electronic form at http://www.aanda.org
The spectra (FITS files) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (18.104.22.168) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/550/A114
© ESO, 2013