W. W. Zeilinger

The Herschel Reference Survey

The Herschel Reference Survey is a Herschel guaranteed time key project and will be a benchmark study of dust in the nearby universe. The survey will complement a number of other Herschel key projects including large cosmological surveys that trace dust in the distant universe. We will use Herschel to produce images of a statistically-complete sample of 323 galaxies at 250, 350, and 500 μm. The sample is volume-limited, containing sources with distances between 15 and 25 Mpc and flux limits in the K band to minimize the selection effects associated with dust and with young high-mass stars and to introduce a selection in stellar mass. The sample spans the whole range of morphological types (ellipticals to late-type spirals) and environments (from the field to the center of the Virgo Cluster) and as such will be useful for other purposes than our own. We plan to use the survey to investigate (i) the dust content of galaxies as a function of Hubble type, stellar mass, and environment; (ii) the connection between the dust content and composition and the other phases of the interstellar medium; and (iii) the origin and evolution of dust in galaxies. In this article, we describe the goals of the survey, the details of the sample and some of the auxiliary observing programs that we have started to collect complementary data. We also use the available multifrequency data to carry out an analysis of the statistical properties of the sample.

The Herschel Space Observatory view of dust in M81

We use Herschel Space Observatory data to place observational constraints on the peak and Rayleigh-Jeans slope of dust emission observed at 70–500 μm in the nearby spiral galaxy M81. We find that the ratios of wave bands between 160 and 500 μm are primarily dependent on radius but that the ratio of 70 to 160 μm emission shows no clear dependence on surface brightness or radius. These results along with analyses of the spectral energy distributions imply that the 160–500 μm emission traces 15–30 K dust heated by evolved stars in the bulge and disc whereas the 70 μm emission includes dust heated by the active galactic nucleus and young stars in star forming regions.

Nearby early-type galaxies with ionized gas - III. Analysis of line-strength indices with new stellar population models

Aims. The paper is devoted to the study of the underlying stellar population of axa0sample of 65xa0nearby early-type galaxies, predominantly located in low density environments, axa0large fraction of which show emission lines. Methods. Ages, metallicities, and [ α /Fe] xa0ratios have been derived through the comparison of Lick indices measured at different galacto-centric distances (7xa0apertures and 4xa0gradients) with new simple stellar populationxa0(SSP) models that account for the presence of α /Fe-enhancement. The SSPs cover axa0wide range of ages (

The puzzlingly large Ca II triplet absorption in dwarf elliptical galaxies

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Probing the molecular interstellar medium of M82 with Herschel-SPIRE spectroscopy

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Nearby early-type galaxies with ionized gas.IV. Origin and powering mechanism of the ionized gas

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Formation and evolution of dwarf elliptical galaxies I. Structural and kinematical properties

10 9 xa0yr), metallicities (0.0004xa0 ≤ Z ≤ 0.05), and [ α /Fe] xa0ratios (0–0.8). To derive the stellar population parameters, we use anxa0algorithm that provides, together with the most likely solution in the (age, Z , [ α /Fe] ) space, the probability density function along the age-metallicity degeneracy. Results. We derive a large spread in age, with SSP-equivalent ages ranging from axa0few toxa015xa0Gyr. Age does not show any significant trend with central velocity dispersionxa0

FIR colours and SEDs of nearby galaxies observed with Herschel

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Embedded disks in Fornax dwarf elliptical galaxies

, but Exa0galaxies appear on average older than lenticulars. On the contrary, axa0significant increasing trend of metallicity and [ α /Fe] withxa0

SPIRE imaging of M 82: Cool dust in the wind and tidal streams

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