The survey description and the near-, mid-, and far-infrared flux properties are presented for the 258 galaxies in the Local Volume Legacy (LVL). LVL is a Spitzer Space Telescope legacy program that surveys the local universe out to 11 Mpc, built upon a foundation of ultraviolet, Hα, and Hubble Space Telescope imaging from 11HUGS (11 Mpc Hα and Ultraviolet Galaxy Survey) and ANGST (ACS Nearby Galaxy Survey Treasury). LVL covers an unbiased, representative, and statistically robust sample of nearby star-forming galaxies, exploiting the highest extragalactic spatial resolution achievable with Spitzer. As a result of its approximately volume-limited nature, LVL augments previous Spitzer observations of present-day galaxies with improved sampling of the lowluminosity galaxy population. The collection of LVL galaxies shows a large spread in mid-infrared colors, likely due to the conspicuous deficiency of 8 μm polycyclic aromatic hydrocarbon emission from low-metallicity, lowluminosity galaxies. Conversely, the far-infrared emission tightly tracks the total infrared emission, with a dispersion in their flux ratio of only 0.1 dex. In terms of the relation between the infrared-to-ultraviolet ratio and the ultraviolet spectral slope, the LVL sample shows redder colors and/or lower infrared-to-ultraviolet ratios than starburst galaxies, suggesting that reprocessing by dust is less important in the lower mass systems that dominate the LVL sample. Comparisons with theoretical models suggest that the amplitude of deviations from the relation found for starburst galaxies correlates with the age of the stellar populations that dominate the ultraviolet/optical luminosities.
1 Based on observations obtained with the Spitzer Space Telescope, which is operated by JPL, CalTech, under NASA Contract 1407.
Abstract. Ionized gas and stellar kinematical parameters have been measured along the major axis of 20 nearby disc galaxies. We discuss the properties of each sample galaxy, distinguishing between those characterized by regular or peculiar kinematics. In early-type disc galaxies, ionized gas tends to rotate faster than stars and to have a lower velocity dispersion (Vg > V and σg < σ ), whereas in late-type spirals, gas and stars show almost the same rotation velocities and velocity dispersions (Vg V and σg σ ). Incorporating the early-type disc galaxies studied by Bertola et al. (1995), Fisher (1997 and Corsini et al. (1999), we have compiled a sample of some 40 galaxies for which the major-axis radial profiles of both the stellar and gaseous components have been measured. The value of σ measured at Re/4 turns out to be strongly correlated with the galaxy morphological type, while σg is not and sometimes takes values above the range expected from thermal motions or small-scale turbulence.
The R-band isophotal map of the Sa galaxy NGC 4698 shows that the inner region of the bulge is elongated perpendicularly to the major axis of the disc. At the same time a central stellar velocity gradient is found along the minor axis of the disc. The same properties have also been recognized in the Sa galaxy NGC 4672. This remarkable geometric and kinematic decoupling is a direct indication that a second event occurred in the history of these galaxies suggesting that acquisition phenomena could play a primary role in the formation of early-type spirals.
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