Adaptive Optics Imaging of IRAS 18276-1431: a bipolar pre-planetary nebula with circumstellar "searchlight beams" and "arcs"

We present high-angular resolution images of the post-AGB nebula IRAS18276-1431 (also known as OH17.7-2.0) obtained with the Keck II Adaptive Optics (AO) system in its Natural Guide Star (NGS) mode in the Kp, Lp, and Ms near-infrared bands. We also present supporting optical F606W and F814W HST images as well as interferometric observations of the 12CO(J=1-0), 13CO(J=1-0), and 2.6mm continuum emission with OVRO. The envelope of IRAS18276-1431 displays a clear bipolar morphology in our optical and NIR images with two lobes separated by a dark waist and surrounded by a faint 4.5"x3.4" halo. Our Kp-band image reveals two pairs of radial ``searchlight beams'' emerging from the nebula center and several intersecting, arc-like features. From our CO data we derive a mass of M>0.38[D/3kpc]^2 Msun and an expansion velocity v_exp=17km/s for the molecular envelope. The density in the halo follows a radial power-law proportional to r^-3, which is consistent with a mass-loss rate increasing with time. Analysis of the NIR colors indicates the presence of a compact central source of ~300-500K dust illuminating the nebula in addition to the central star. Modeling of the thermal IR suggests a two-shell structure in the dust envelope: 1) an outer shell with inner and outer radius R_in~1.6E16cm and R_out>~1.25E17cm, dust temperature T_d~105-50K, and a mean mass-loss rate of Mdot~1E-3Msun/yr; and 2) an inner shell with R_in~6.3E14cm, T_dust~500-105K, and Mdot~3E-5Msun/yr. An additional population of big dust grains (radius a>~0.4mm) with T_dust=150-20K and mass M_dust=(0.16-1.6)E-3 [D/3kpc]^2 Msun can account for the observed sub-mm and mm flux excess. The mass of the envelope enclosed within R_out=1.25E17cm derived from SED modeling is ~1[D/3kpc]^2 Msun.Comment: 46 pages, 14 figures, 3 tables, accepted for publication in ApJ. Figures 12 & 13 in low resolution. Full resolution versions are available upon request to the first autho

Stellar Population gradients in galaxy discs from the CALIFA survey

While studies of gas-phase metallicity gradients in disc galaxies are common, very little has been done in the acquisition of stellar abundance gradients in the same regions. We present here a comparative study of the stellar metallicity and age distributions in a sample of 62 nearly face-on, spiral galaxies with and without bars, using data from the CALIFA survey. We measure the slopes of the gradients and study their relation with other properties of the galaxies. We find that the mean stellar age and metallicity gradients in the disc are shallow and negative. Furthermore, when normalized to the effective radius of the disc, the slope of the stellar population gradients does not correlate with the mass or with the morphological type of the galaxies. Contrary to this, the values of both age and metallicity at $\sim$2.5 scale-lengths correlate with the central velocity dispersion in a similar manner to the central values of the bulges, although bulges show, on average, older ages and higher metallicities than the discs. One of the goals of the present paper is to test the theoretical prediction that non-linear coupling between the bar and the spiral arms is an efficient mechanism for producing radial migrations across significant distances within discs. The process of radial migration should flatten the stellar metallicity gradient with time and, therefore, we would expect flatter stellar metallicity gradients in barred galaxies. However, we do not find any difference in the metallicity or age gradients in galaxies with without bars. We discuss possible scenarios that can lead to this absence of difference.Comment: 24 pages, 17 figures, accepted for publication in A&

CALIFA, the Calar Alto Legacy Integral Field Area survey: I. Survey presentation

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 $\sim600$ 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 \sim1.3\sq\arcmin', with a 100% covering factor by adopting a three-pointing dithering scheme. The optical wavelength range is covered from 3700 to 7000 {\AA}, using two overlapping setups (V500 and V1200), with different resolutions: R\sim850 and R\sim1650, 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. We conclude from this first look at the data that CALIFA will be an important resource for archaeological studies of galaxies in the Local Universe.Comment: 32 pages, 29 figures, Accepted for publishing in Astronomy and Astrophysic

Polycyclic aromatic hydrocarbons in the dwarf galaxy IC 10

Infrared observations from the Spitzer Space Telescope archive are used to study the dust component of the interstellar medium in the IC~10 irregular galaxy. Dust distribution in the galaxy is compared to the distributions of H$\alpha$ and [SII] emission, neutral hydrogen and CO clouds, and ionizing radiation sources. The distribution of polycyclic aromatic hydrocarbons (PAH) in the galaxy is shown to be highly non-uniform with the mass fraction of these particles in the total dust mass reaching 4%. PAHs tend to avoid bright HII regions and correlate well with atomic and molecular gas. This pattern suggests that PAHs form in the dense interstellar gas. We propose that the significant decrease of the PAH abundance at low metallicity is observed not only globally (at the level of entire galaxies), but also locally (at least, at the level of individual HII regions). We compare the distribution of the PAH mass fraction to the distribution of high-velocity features, that we have detected earlier in wings of H$\alpha$ and SII lines, over the entire available galaxy area. No conclusive evidence for shock destruction of PAHs in the IC~10 galaxy could be found.Comment: Accepted for publication in Astronomy Report

Echelle long-slit optical spectroscopy of evolved stars

We present echelle long-slit optical spectra of a sample of objects evolving off the AGB, most of them in the pre-planetary nebula (pPN) phase, obtained with the ESI and MIKE spectrographs at Keck-II and Magellan-I, respectively. The total wavelength range covered with ESI (MIKE) is ~3900 to 10900 A (~3600 to 7200A). In this paper, we focus our analysis mainly on the Halpha profiles. Prominent Halpha emission is detected in half of the objects, most of which show broad Halpha wings (up to ~4000 km/s). In the majority of the Halpha-emission sources, fast, post-AGB winds are revealed by P-Cygni profiles. In ~37% of the objects Halpha is observed in absorption. In almost all cases, the absorption profile is partially filled with emission, leading to complex, structured profiles that are interpreted as an indication of incipient post-AGB mass-loss. All sources in which Halpha is seen mainly in absorption have F-G type central stars, whereas sources with intense Halpha emission span a larger range of spectral types from O to G. Shocks may be an important excitation agent of the close stellar surroundings for objects with late type central stars. Sources with pure emission or P Cygni Halpha profiles have larger J-K color excess than objects with Halpha mainly in absorption, which suggests the presence of warm dust near the star in the former. The two classes of profile sources also segregate in the IRAS color-color diagram in a way that intense Halpha-emitters have dust grains with a larger range of temperatures. (abridged)Comment: 68 pages, 14 figures, accepted for publication in ApJS (abstract abridged

Chemical and Photometric Evolution of Extended Ultraviolet Disks: Optical Spectroscopy of M83 (NGC5236) and NGC4625

We present the results from the analysis of optical spectra of 31 Halpha-selected regions in the extended UV (XUV) disks of M83 (NGC5236) and NGC4625 recently discovered by GALEX. The spectra were obtained using IMACS at Las Campanas Observatory 6.5m Magellan I telescope and COSMIC at the Palomar 200-inch telescope, respectively for M83 and NGC4625. The line ratios measured indicate nebular oxygen abundances (derived from the R23 parameter) of the order of Zsun/5-Zsun/10. For most emission-line regions analyzed the line fluxes and ratios measured are best reproduced by models of photoionization by single stars with masses in the range 20-40 Msun and oxygen abundances comparable to those derived from the R23 parameter. We find indications for a relatively high N/O abundance ratio in the XUV disk of M83. Although the metallicities derived imply that these are not the first stars formed in the XUV disks, such a level of enrichment could be reached in young spiral disks only 1 Gyr after these first stars would have formed. The amount of gas in the XUV disks allow maintaining the current level of star formation for at least a few Gyr.Comment: 52 pages, 8 tables, 7 figures, accepted for publication in Ap

CALIFA : a diameter-selected sample for an integral field spectroscopy galaxy survey

JMA acknowledges support from the European Research Council Starting Grant (SEDmorph; P.I. V. Wild).We describe and discuss the selection procedure and statistical properties of the galaxy sample used by the Calar Alto Legacy Integral Field Area (CALIFA) survey, a public legacy survey of 600 galaxies using integral field spectroscopy. The CALIFA "mother sample" was selected from the Sloan Digital Sky Survey (SDSS) DR7 photometric catalogue to include all galaxies with an r-band isophotal major axis between 45 '' and 79 : 2 '' and with a redshift 0 : 005 M-r > -23 : 1 and over a stellar mass range between 10(9.7) and 10(11.4) M-circle dot. In particular, within these ranges, the diameter selection does not lead to any significant bias against - or in favour of - intrinsically large or small galaxies. Only below luminosities of M-r = -19 (or stellar masses <10(9.7) M-circle dot) is there a prevalence of galaxies with larger isophotal sizes, especially of nearly edge-on late-type galaxies, but such galaxies form <10% of the full sample. We estimate volume-corrected distribution functions in luminosities and sizes and show that these are statistically fully compatible with estimates from the full SDSS when accounting for large-scale structure. For full characterization of the sample, we also present a number of value-added quantities determined for the galaxies in the CALIFA sample. These include consistent multi-band photometry based on growth curve analyses; stellar masses; distances and quantities derived from these; morphological classifications; and an overview of available multi-wavelength photometric measurements. We also explore different ways of characterizing the environments of CALIFA galaxies, finding that the sample covers environmental conditions from the field to genuine clusters. We finally consider the expected incidence of active galactic nuclei among CALIFA galaxies given the existing pre-CALIFA data, finding that the final observed CALIFA sample will contain approximately 30 Sey2 galaxies.Peer reviewe

Cloning of cDNA and chromosomal location of genes encoding the three types of subunits of the wheat tetrameric inhibitor of insect a-amylase

We have characterized three cDNA clones corresponding to proteins CM1, CM3 and CM16, which represent the three types of subunits of the wheat tetrameric inhibitor of insect -amylases. The deduced amino acid sequences of the mature polypeptides are homologous to those of the dimeric and monomeric -amylase inhibitors and of the trypsin inhibitors. The mature polypeptides are preceded by typical signal peptides. Southern blot analysis of appropriate aneuploids, using the cloned cDNAs as probes, has revealed the location of genes for subunits of the CM3 and of the CM16 type within a few kb of each other in chromosomes 4A, 4B and 4D, and those for the CM1 type of subunit in chromosomes 7A, 7B and 7D. Known subunits of the tetrameric inhibitor corresponding to genes from the B and D genomes have been previously characterized. No proteins of this class have been found to be encoded by the A genome in hexaploid wheat (genomes AA, BB, DD) or in diploid wheats (AA) and no anti -amylase activity has been detected in the latter, so that the A-genome genes must be either silent (pseudogenes) or expressed at a much lower level

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13