Context. Resonance rings and pseudorings (here collectively called rings) are thought to be related to the gathering of material near dynamical resonances caused by non-axisymmetries in galaxy discs. This means that they are the result of secular evolution processes that redistribute material and angular momentum in discs. Studying them may give

We have performed two-dimensional multicomponent decomposition of 144 local barred spiral galaxies using 3.6 μm images from the Spitzer Survey of Stellar Structure in Galaxies. Our model fit includes up to four components (bulge, disk, bar, and a point source) and, most importantly, takes into account disk breaks. We find that ignoring the disk

We present near-infrared (H- and K-band) integral-field observations of the inner ˜700 pc of the active spiral galaxy NGC 613, obtained with SINFONI on the Very Large Telescope. We use emission-line ratios to determine the dominant excitation mechanisms in different regions within our field of view, in particular, the active nucleus and the star

The morphology of galaxies can be quantified to some degree using a set of scale-invariant parameters. Concentration (C), asymmetry (A), smoothness (S), the Gini index (G), the relative contribution of the brightest pixels to the second-order moment of the flux (M 20), ellipticity (E), and the Gini index of the second-order moment (GM ) have all

Star-forming regions that are visible at 3.6 μm and Hα but not in the u, g, r, i, z bands of the Sloan Digital Sky Survey are measured in five nearby spiral galaxies to find extinctions averaging ~3.8 mag and stellar masses averaging ~5 × 104 M ☉. These regions are apparently young star complexes embedded in dark filamentary shock fronts connected

We have developed a method for finding dynamical resonances in disk galaxies using the change in sense of the radial component of the in-plane velocity at a resonance radius. Using simulations we show that we would expect to find these changes at corotation radii with a weaker effect at the Lindblad resonances. The method works well with

We investigate the far infrared (IR) spectrum of NGC 1266, a S0 galaxy that contains a massive reservoir of highly excited molecular gas. Using the Herschel Fourier Transform Spectrometer, we detect the 12CO ladder up to J = (13-12), [C I] and [N II] lines, and also strong water lines more characteristic of UltraLuminous IR Galaxies (ULIRGs). The

From an analysis of almost 2000 Galaxy Evolution Explorer images of galaxies with morphological types ranging from E to Sab, we have found a significant subset (28 per cent) that show ultraviolet (UV) emission outside R25. We have obtained Hα imaging of 10 such galaxies, and found that their star formation rates are similar in the UV and in Hα

We use recently derived ages for 61 Milky Way (MW) globular clusters (GCs) to show that their age-metallicity relation (AMR) can be divided into two distinct, parallel sequences at [Fe/H] ≳ -1.8. Approximately one-third of the clusters form an offset sequence that spans the full range in age (˜10.5-13 Gyr), but is more metal rich at a given age by

We present 12CO J = 3→2 maps of NGC 2976 and NGC 3351 obtained with the James Clerk Maxwell Telescope (JCMT), both early targets of the JCMT Nearby Galaxy Legacy Survey (NGLS). We combine the present observations with 12CO J = 1→0 data and find that the computed 12CO J = 3→2 to 12CO J = 1→0 line ratio (R31) agrees with values measured in other NGLS

Stellar bars can lead to gas inflow toward the center of a galaxy and stimulate nuclear star formation. However, there is no compelling evidence on whether they also feed a central supermassive black hole: by measuring the fractions of barred active and inactive galaxies, previous studies have yielded conflicting results. In this paper, we aim to

Ages have been derived for 55 globular clusters (GCs) for which Hubble Space Telescope Advanced Camera for Surveys photometry is publicly available. For most of them, the assumed distances are based on fits of theoretical zero-age horizontal-branch (ZAHB) loci to the lower bound of the observed distributions of HB stars, assuming reddenings from

We study the m = 1 distortions (lopsidedness) in the stellar components of 167 nearby galaxies that span a wide range of morphologies and luminosities. We confirm the previous findings of (1) a high incidence of lopsidedness in the stellar distributions, (2) increasing lopsidedness as a function of radius out to at least 3.5 exponential scale

We have analyzed the radial distribution of old stars in a sample of 218 nearby face-on disks, using deep 3.6 μm images from the Spitzer Survey of Stellar Structure in Galaxies. In particular, we have studied the structural properties of those disks with a broken or down-bending profile. We find that, on average, disks with a genuine single

Building on our previous spectroscopic and photometric analysis of the isolated Local Group dwarf irregular (dIrr) galaxy WLM, we present a comparison of the metallicities of its red giant branch stars with respect to the well-studied Local Group dwarf spheroidal galaxies (dSphs) and Magellanic Clouds. We calculate a mean metallicity of [Fe/H] =–1

We describe the results of the world-wide observing campaign of the highly eccentric Be binary system δ Scorpii 2011 periastron passage which involved professional and amateur astronomers. Our spectroscopic observations provided a precise measurement of the system orbital period at 10.8092 ± 0.0005 yr. Fitting of the He II 4686 Å line radial

Using a simple model of photodissociated atomic hydrogen on a galactic scale, it is possible to derive total hydrogen volume densities. These densities, obtained through a combination of atomic hydrogen, far-ultraviolet and metallicity data, provide an independent probe of the combined atomic and molecular hydrogen gas in galactic discs. We present

We present a study of the kinematics of the isolated spiral galaxy NGC 864, using Hα Fabry-Perot data obtained with the Galaxy Hα Fabry-Perot System (GHαFaS) instrument at the William Herschel Telescope in La Palma, complemented with images at 3.6 μm, in the R band and in Hα filter, and integral-field spectroscopic data. The resulting data cubes

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

The "Cosmic Evolution Survey" (COSMOS) enables the study of the spectral energy distributions (SEDs) of active galactic nuclei (AGNs) because of the deep coverage and rich sampling of frequencies from X-ray to radio. Here we present an SED catalog of 413 X-ray (XMM-Newton)-selected type 1 (emission line FWHM > 2000 km s–1) AGNs with Magellan, SDSS