The WINGS Survey: a progress report

A two-band (B and V) wide-field imaging survey of a complete, all-sky X-ray selected sample of 78 clusters in the redshift range z=0.04-0.07 is presented. The aim of this survey is to provide the astronomical community with a complete set of homogeneous, CCD-based surface photometry and morphological data of nearby cluster galaxies located within 1.5 Mpc from the cluster center. The data collection has been completed in seven observing runs at the INT and ESO-2.2m telescopes. For each cluster, photometric data of about 2500 galaxies (down to V~23) and detailed morphological information of about 600 galaxies (down to V~21) are obtained by using specially designed automatic tools. As a natural follow up of the photometric survey, we also illustrate a long term spectroscopic program we are carrying out with the WHT-WYFFOS and AAT-2dF multifiber spectrographs. Star formation rates and histories, as well as metallicity estimates will be derived for about 350 galaxies per cluster from the line indices and equivalent widths measurements, allowing us to explore the link between the spectral properties and the morphological evolution in high- to low-density environments, and across a wide range in cluster X-ray luminosities and optical properties.Comment: 12 pages, 10 eps figures, Proceedings of the SAIt Conference 200

Evidence for a Young Stellar Population in NGC 5018

Two absorption line indices, Ca II and Hdelta/FeI4045, measured from high resolution spectra are used with evolutionary synthesis models to verify the presence of a young stellar population in NGC 5018. The derived age of this population is about ~2.8 Gyr with a metallicity roughly solar and it completely dominates the integrated light of the galaxy near 4000 A.Comment: 13 pages, 7 figures (figs 3-7 are color figures), to be published in the May 2000 issue of the Astrophysical Journa

WINGS: a WIde-field Nearby Galaxy-cluster Survey. I - Optical imaging

This is the first paper of a series that will present data and scientific results from the WINGS project, a wide-field, multiwavelength imaging and spectroscopic survey of galaxies in 77 nearby clusters. The sample was extracted from the ROSAT catalogs with constraints on the redshift (0.0420). The global goal of the WINGS project is the systematic study of the local cosmic variance of the cluster population and of the properties of cluster galaxies as a function of cluster properties and local environment. This data collection will allow to define a local 'Zero-Point' reference against which to gauge the cosmic evolution when compared to more distant clusters. The core of the project consists of wide-field optical imaging of the selected clusters in the B and V bands. We have also completed a multi-fiber, medium resolution spectroscopic survey for 51 of the clusters in the master sample. In addition, a NIR (JK) survey of ~50 clusters and an H_alpha + UV survey of some 10 clusters are presently ongoing, while a very-wide-field optical survey has also been programmed. In this paper we briefly outline the global objectives and the main characteristics of the WINGS project. Moreover, the observing strategy and the data reduction of the optical imaging survey (WINGS-OPT) are presented. We have achieved a photometric accuracy of ~0.025mag, reaching completeness to V~23.5. Field size and resolution (FWHM) span the absolute intervals (1.6-2.7)Mpc and (0.7-1.7)kpc, respectively, depending on the redshift and on the seeing. This allows the planned studies to get a valuable description of the local properties of clusters and galaxies in clusters.Comment: 24 pages, 15 figures, Accepted by Astronomy and Astrophysic

Lopsided Galaxies, Weak Interactions and Boosting the Star Formation Rate

To investigate the link between weak tidal interactions in disk galaxies and the boosting of their recent star formation, we obtain images and spatially integrated spectra (3615A < lambda < 5315A) for 40 late-type spiral galaxies (Sab-Sbc) with varying degrees of lopsidedness (a dynamical indicator of weak interactions). We quantify lopsidedness as the amplitude of the m=1 Fourier component of the azimuthal surface brightness distribution, averaged over a range of radii. We compare the young stellar content, quantified by EW(H\delta_abs) and the strength of the 4000 Angstrom break (D_4000), with lopsidedness and find a 3-4 sigma correlation between the two. We also find a 3.2 sigma correlation between EW(H\beta_emission) and lopsidedness. Using the evolutionary population synthesis code of Bruzual & Charlot we model the spectra as an ``underlying population'' and a superimposed ``boost population'' with the aim of constraining the fractional boost in the SFR averaged over the past 0.5 Gyr (the characteristic lifetime of lopsidedness). From the difference in both EW(H\delta_abs) and D_4000 between the most and least symmetric thirds of our sample, we infer that ~ 1x10^9 M_solar of stars are formed over the duration of a lopsided event in addition to the ``underlying'' SFH (assuming a final galactic stellar mass of 10^10 M_solar). This corresponds to a factor of 8 increase in the SFR over the past 5x10^8 years. For the nuclear spectra, all of the above correlations except D_4000 vs. are weaker than for the disk, indicating that in lopsided galaxies, the SF boost is not dominated by the nucleus.Comment: 35 pages, including 10 figures, to appear in the Astrophysical Journal, abridged abstrac

Cultural Benefits from Metropolitan River Recreation -- San Antonio Prototype

This study analyzes the response to an outstanding design and development of a park-business complex along a natural river in the heart of a major city, The San Antonio River Walk. The research includes both those who visit and those who control or influence its development. The River Walk refers to a horseshoe bend in the San Antonio River covering an area about four by six blocks in size in the central business district. This portion of the river lies in a deep cut, about 25 feet below street level, and is flanked by huge trees, lush plant growth and many shops, restaurants, and hotels. A continuous promenade parallels the river on both sides and the fifty-foot river is bridged many times providing both automobile and pedestrian crossing. The research flowed along several lines in order to obtain full understanding of this unusual site. Because designed environments are seldom evaluated after construction, this project sought to obtain results on the following objectives: 1. to sketch the present trends in river development for recreation in U.S. cities, 2. to analyze the landscape character of the River Walk, and 3. to obtain the opinions and attitudes toward the use and characteristics of the River Walk from: a) the visitors at all seasons, b) the voters of San Antonio, c) the organizations and agencies controlling and influencing development, and d) the property owners contiguous to the River Walk. To determine the status of urban river development in the U.S., a survey of the fifty largest cities was conducted in addition to a review of literature and visits to ten cities with urban water development. Data from these sources revealed the following: There is at present very little use made of urban rivers and most have been badly abused. Many plans are being made in most cities for the realignment of policies governing their waterfronts. A few cities are beginning the implementation or redevelopment that incorporates the open space, esthetic and recreational values of their waters

The Butcher-Oemler Effect at Moderate Redshift

We present the results of Butcher-Oemler-style analysis of three moderate- redshift (0.1<z<0.2) clusters which have bimodal X-ray surface brightness profiles. We find that at least two of these clusters exhibit unusually high fractions of blue galaxies as compared to clusters at comparable redshifts studied by Butcher and Oemler (1984). This implies that star formation is occurring in a high fraction of the galaxies in the two clusters. Our results are consistent with hierarchical clustering models in which subcluster- subcluster mergers create shocks in the intracluster medium. The shocks, in turn, induce simultaneous starbursts in a large fraction of cluster galaxies. Our study therefore lends weight to the hypothesis that the Butcher-Oemler effect is an environmental, as well as evolutionary, phenomenon.Comment: 22 pages, 8 figures; accepted for publication in A

Piloted Simulation Assessment of the Impact of Flexible Structures on Handling Qualities of Generic Supersonic Aircraft

The NASA Langley Research Center Cockpit Motion Facility (CMF) was used to conduct a piloted simulation assessment of the impact of flexible structures on flying qualities. The CMF was used because of its relatively high bandwidth, six degree-of-freedom motion capability. Previous studies assessed and attempted to mitigate the effects of multiple dynamic aeroservoelastic modes (DASE). Those results indicated problems existed, but the specific cause and effect was difficult to ascertain. The goal of this study was to identify specific DASE frequencies, damping ratios, and gains that cause degradation in handling qualities. A generic aircraft simulation was developed and designed to have Cooper-Harper Level 1 handling qualities when flown without DASE models. A test matrix of thirty-six DASE modes was implemented. The modes had frequencies ranging from 1 to 3.5 Hz and were applied to each axis independently. Each mode consisted of a single axis, frequency, damping, and gain, and was evaluated individually by six subject pilots with test pilot backgrounds. Analysis completed to date suggests that a number of the DASE models evaluated degrade the handling qualities of this class of aircraft to an uncontrollable condition

Exogenous GDF11 Induces Cardiac and Skeletal Muscle Dysfunction and Wasting

Growth differentiation factor 11 (GDF11), a TGF-beta superfamily member, is highly homologous to myostatin and essential for embryonic patterning and organogenesis. Reports of GDF11 effects on adult tissues are conflicting, with some describing anti-aging and pro-regenerative activities on the heart and skeletal muscle while others opposite or no effects. Herein, we sought to determine the in vivo cardiac and skeletal muscle effects of excess GDF11. Mice were injected with GDF11 secreting cells, an identical model to that used to initially identify the in vivo effects of myostatin. GDF11 exposure in mice induced whole body wasting and profound loss of function in cardiac and skeletal muscle over a 14-day period. Loss of cardiac mass preceded skeletal muscle loss. Cardiac histologic and echocardiographic evaluation demonstrated loss of ventricular muscle wall thickness, decreased cardiomyocyte size, and decreased cardiac function 10 days following initiation of GDF11 exposure. Changes in skeletal muscle after GDF11 exposure were manifest at day 13 and were associated with wasting, decreased fiber size, and reduced strength. Changes in cardiomyocytes and skeletal muscle fibers were associated with activation of SMAD2, the ubiquitin–proteasome pathway and autophagy. Thus, GDF11 over administration in vivo results in cardiac and skeletal muscle loss, dysfunction, and death. Here, serum levels of GDF11 by Western blotting were 1.5-fold increased over controls. Although GDF11 effects in vivo are likely dose, route, and duration dependent, its physiologic changes are similar to myostatin and other Activin receptors ligands. These data support that GDF11, like its other closely related TGF-beta family members, induces loss of cardiac and skeletal muscle mass and function

Sizes, Shapes, and Correlations of Lyman Alpha Clouds and Their Evolution in the CDM+Λ+\Lambda Universe

This study analyzes the sizes, shapes and correlations of \lya clouds produced by a hydrodynamic simulation of a spatially flat CDM universe with a non-zero cosmological constant ($\Omega_0=0.4$, $\Lambda_0=0.6$, $\sigma_8 =0.79$), over the redshift range $2\le z \le 4$. The \lya clouds range in size from several kiloparsecs to about a hundred kiloparsecs in proper units, and they range in shape from roundish, high column density regions with \nhi\ge 10^{15} cm^{-2} to low column density sheet-like structures with \nhi \le 10^{13} cm^{-2} at z=3. The most common shape found in the simulation resembles that of a flattened cigar. The physical size of a typical cloud grows with time roughly as $(1+z)^{-3/2}$ while its shape hardly evolves (except for the most dense regions $\rho_{cut}>30$). Our result indicates that any simple model with a population of spheres (or other shapes) of a uniform size is oversimplified; if such a model agrees with observational evidence, it is probably only by coincidence. We also illustrate why the use of double quasar sightlines to set lower limits on cloud sizes is useful only when the perpendicular sightline separation is small ($\Delta r \le 50h^{-1}$ kpc). Finally, we conjecture that high column density \lya clouds (\nhi\ge 10^{15} cm^{-2}) may be the progenitors of the lower redshift faint blue galaxies. This seems plausible because their correlation length, number density (extrapolated to lower redshift) and their masses are in fair agreement with those observed.Comment: ApJ, in press, 34 pages, 21 figures, figs (1a,b,c) can be at http://astro.princeton.edu/~cen/LYASSC/lyassc.htm

GMRT Detection of HI 21 cm-line Absorption from the Peculiar Galaxy in Abell 2125

Using the recently completed Giant Meterwave Radio Telescope, we have detected the HI 21 cm-line absorption from the peculiar galaxy C153 in the galaxy cluster Abell 2125. The HI absorption is at a redshift of 0.2533, with a peak optical depth of 0.36. The full width at half minimum of the absorption line is 100 km/s. The estimated column density of atomic Hydrogen is 0.7e22(Ts/100K) per sq. cm. The HI absorption is redshifted by ~ 400 km/s compared to the [OIII] emission line from this system. We attribute this to an in-falling cold gas, or to an out-flowing ionised gas, or to a combination of both as a consequence of tidal interactions of C153 with either a cluster galaxy or the cluster potential.Comment: 9 pages, 2 figures, uses jaa.sty (included