The final product of galaxy evolution through cosmic time is the population of galaxies in the local universe. These galaxies are also those that can be studied in most detail, thus providing a stringent benchmark for our understanding of galaxy evolution. Through the huge success of spectroscopic single-fiber, statistical surveys of the Local Universe in the last decade, it has become clear, however, that an authoritative observational description of galaxies will involve measuring their spatially resolved properties over their full optical extent for a statistically significant sample. We present here the Calar Alto Legacy Integral Field Area (CALIFA) survey, which has been designed to provide a first step in this direction. We summarize the survey goals and design, including sample selection and observational strategy. We also showcase the data taken during the first observing runs (June/July 2010) and outline the reduction pipeline, quality control schemes and general characteristics of the reduced data. This survey is obtaining spatially resolved spectroscopic information of a diameter selected sample of ∼600 galaxies in the Local Universe (0.005 < z < 0.03). CALIFA has been designed to allow the building of two-dimensional maps of the following quantities: (a) stellar populations: ages and metallicities; (b) ionized gas: distribution, excitation mechanism and chemical abundances; and (c) kinematic properties: both from stellar and ionized gas components. CALIFA uses the PPAK integral field unit (IFU), with a hexagonal field-of-view of ∼1.3 , with a 100% covering factor by adopting a three-pointing dithering scheme. The optical wavelength range is covered from 3700 to 7000 Å, using two overlapping setups (V500 and V1200), with different resolutions: R ∼ 850 and R ∼ 1650, respectively. CALIFA is a legacy survey, intended for the community. The reduced data will be released, once the quality has been guaranteed. The analyzed data fulfill the expectations of the original observing proposal, on the basis of a set of quality checks and exploratory analysis: (i) the final datacubes reach a 3σ limiting surface brightness depth of ∼23.0 mag/arcsec 2 for the V500 grating data (∼22.8 mag/arcsec 2 for V1200); (ii) about ∼70% of the covered field-of-view is above this 3σ limit; (iii) the data have a blue-to-red relative flux calibration within a few percent in most of the wavelength range; (iv) the absolute flux calibration is accurate within ∼8% with respect to SDSS; (v) the measured spectral resolution is ∼85 km s −1 for V1200 (∼150 km s −1 for V500); (vi) the estimated accuracy of the wavelength calibration is ∼5 km s −1 for the V1200 data (∼10 km s −1 for the V500 data); (vii) the aperture matched CALIFA and SDSS spectra are qualitatively and quantitatively similar. Finally, we show that we are able to carry out all measurements indicated above, recovering the properties of the stellar populations, the ionized gas and the kinematics of both components. The associated maps illustrate the spatial variation of...

We have explored radial color and stellar surface mass density profiles for a sample of 85 latetype spiral galaxies with deep (down to ∼27 mag arcsec −2 ) SDSS g ′ and r ′ band surface brightness profiles. About 90% of the light profiles have been classified as broken exponentials, exhibiting either truncations (Type II galaxies) or antitruncations (Type III galaxies). The color profiles of Type II galaxies show a "U shape" with a minimum of (g ′ −r ′ ) = 0.47 ± 0.02 mag at the break radius. Around the break radius, Type III galaxies have a plateau region with a color of (g ′ − r ′ ) = 0.57 ± 0.02. Using the color to calculate the stellar surface mass density profiles reveals a surprising result. The breaks, well established in the light profiles of the truncated galaxies, are almost gone, and the mass profiles now resemble those of the pure exponential (Type I) galaxies. This result suggests that the origin of the break in Type II galaxies is more likely due to a radial change in stellar population than being associated with an actual drop in the distribution of mass. Type III galaxies, however, seem to preserve their shape in the stellar mass density profiles. We find that the stellar surface mass density at the break for truncated galaxies is 13.6 ± 1.6 M ⊙ pc −2 and for the antitruncated ones is 9.9 ± 1.3 M ⊙ pc −2 for the antitruncated ones. We estimate that the fraction of stellar mass outside the break radius is ∼15% for truncated galaxies and ∼9% for antitruncated galaxies.

The mechanism causing breaks in the radial surface‐brightness distribution of spiral galaxies is not yet well known. Despite theoretical efforts, there is not a unique explanation for these features and the observational results are not conclusive. In an attempt to address this problem, we have selected a sample of 34 highly inclined spiral galaxies present in both the Sloan Digital Sky Survey (SDSS) and the Spitzer Survey of Stellar Structure in Galaxies (S4G). We have measured the surface‐brightness profiles in the five Sloan optical bands and in the 3.6‐μm Spitzer band. We have also calculated the colour and stellar surface mass density profiles using the available photometric information, finding two differentiated features: an innermost break radius at distances of ∼8 ± 1 kpc [0.77 ± 0.06 R25] and a second characteristic radius, or truncation radius, close to the outermost optical extent (∼14 ± 2 kpc [1.09 ± 0.05 R25]) of the galaxy. We propose in this work that breaks might be phenomena related to a threshold in the star formation, while truncations are more likely a real drop in the stellar mass density of the disc associated with the maximum angular momentum of the stars.