B, V, I photometry of 20 dwarf irregular galaxies within 10 Mpc

CCD photometry is presented for 20 dIrr galaxies situated in the nearby complexes CenA/M83, and CVnI as well as in the general field of the Local Volume. We present integrated magnitudes of the galaxies in   B , V , I   bands and also surface brightness profiles to a median isophote  μ _B ∼ 28  mag arcsec⁻². The popular Sersic parametrization of surface brightness profiles generally does a poor job of simultaneously fitting the inner cores and outer exponential surface brightness fall-offs observed in many of our targets. The observed sample is a part of a general project to image about 500 nearby  ( D < 10 Mpc)  dwarf galaxies in multiple bands.     

The anomalous properties of Markarian 1460

We present and discuss optical, near-infrared and H  i measurements of the galaxy Markarian 1460 at a distance of 19 Mpc in the Ursa Major Cluster. This low-luminosity ( M _B =−14) galaxy is unusual because (i) it is blue ( B − R =0.8) and has the spectrum of an H  ii galaxy, (ii) it has a light profile that is smooth and well fitted by an r ^1/4 and not an exponential function at all radii larger than the seeing, and (iii) it has an observed central brightness of about μ _B =20 mag arcsec⁻² , intermediate between those of elliptical galaxies (on the bright μ _B side) and normal low-luminosity dwarf irregular (on the low μ _B side) galaxies. No other known galaxy exhibits all these properties in conjunction. On morphological grounds this galaxy looks like a normal distant luminous elliptical galaxy, since the Fundamental Plane tells us that higher luminosity normal elliptical galaxies tend to have lower surface-brightnesses. Markarian 1460 has 2×10⁷ M_⊙ of H  i and a ratio M (H  i )/ L _B of 0.2, which is low compared to the typical values for star-forming dwarf galaxies. From the high surface-brightness and r ^1/4 profile, we infer that the baryonic component of Markarian 1460 has become self-gravitating through dissipative processes. From the colours, radio continuum, H  i and optical emission line properties, and yet smooth texture, we infer that Markarian 1460 has had significant star formation as recently as ∼1 Gyr ago but not today.     

An investigation of lead chromate (crocoite-PbCrO4) and other inorganic pigments in aged traffic paint samples from Hamilton,Ohio: implications for lead in the environment

Traffic paint samples collected from roads in the City of Hamilton, Butler County, OH, USA were investigated to determine whether or not pigments are hazardous and are of environmental concern. Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicate that white and gray paint samples are dominated by calcite, rutile, anatase and quartz and blue traffic paint samples are dominated by calcite and barite. XRD and SEM indicate that most yellow traffic paints have lead chromate (crocoite-PbCrO₄) with common particle sizes that are typically 125–350 nm in length and 75–200 nm in width. Larger aggregates of several micrometers in diameter are also observed. The solubility of PbCrO₄ (1.34 × 10^?7 mol/L at 25 °C) combined with an increase in solubility with exposure to 0.05–0.25 M NaCl and CaCl₂ road treatments solutions as demonstrated by basic batch experiments likely makes PbCrO₄ from traffic paint a potential source for lead pollution in surface water and groundwater that is not fully recognized.     

Tracing the warm–hot intergalactic medium in the local Universe

We present a simple method for tracing the spatial distribution and predicting the physical properties of the Warm–Hot Intergalactic Medium (WHIM), from the map of galaxy light in the Local Universe. Under the assumption that biasing is local and monotonic we map the  ∼2 h ⁻¹ Mpc  smoothed density field of galaxy light into the mass-density field, from which we infer the spatial distribution of the WHIM in the Local Supercluster. Taking into account the scatter in the WHIM density–temperature and density–metallicity relation, extracted from the z = 0 outputs of high-resolution and large-box-size hydrodynamical cosmological simulations, we are able to quantify the probability of detecting WHIM signatures in the form of absorption features in the X-ray spectra, along arbitrary directions in the sky. To illustrate the usefulness of this semi-analytical method we focus on the WHIM properties in the Virgo cluster region.