710 research outputs found
Not in my back yard! Sports stadia location and the property market
In recent years sports stadia have been built in the UK, not only for their intended sporting purpose but with the twin aim of stimulating economic and physical regeneration. However, proposals to locate stadia in urban areas often prompt a negative reaction from local communities, fearing a decline in property prices. This paper will use a case study of the Millennium Stadium in Cardiff and the City of Manchester Stadium to illustrate that in contrast to this widely held belief, sports stadia can actually enhance the value of residential property. Furthermore, it will argue that stadia also contribute indirectly to property value through the creation of pride, confidence and enhanced image of an area.</p
A Simple Scaling Analysis of X-ray Emission and Absorption in Hot-Star Winds
We present a simple analysis of X-ray emission and absorption for hot-star
winds, designed to explore the natural scalings of the observed X-ray
luminosity with wind and sstellar properties. We show that an exospheric
approximation, in which all of the emission above the optical depth unity
radius escapes the wind, reproduces very well the detailed expression for
radiation transport through a spherically symmetric wind. Using this
approximation we find that the X-ray luminosity scales naturally with the
wind density parameter \Mdot/\vinf, obtaining L_x \sim (\Mdot/\vinf)^2 for
optically thin winds, and L_x \sim (\Mdot/\vinf)^{1+s} for optically thick
winds with an X-ray filling factor that varies in radius as . These
scalings with wind density contrast with the commonly inferred empirical
scalings of X-ray luminosity with bolometric luminosity . The
empirically derived linear scaling of for thick winds can
however be reproduced, through a delicate cancellation of emission and
absorption, if one assumes modest radial fall-off in the X-ray filling factor
( or , depending on details of the secondary
scaling of wind density with luminosity). We also explore the nature of the
X-ray spectral energy distribution in the context of this model, and find that
the spectrum is divided into a soft, optically thick part and a hard, optically
thin part. Finally, we conclude that the energy-dependent emissivity must have
a high-energy cut-off, corresponding to the maximum shock energy, in order to
reproduce the general trends seen in X-ray spectral energy distributions of hot
stars.Comment: 16 pages, 2 figures, requiress aaspp4.sty, accepted by Astrophysical
Journal, to appear in the Aug 10, 1999 issue. Several minor changes have been
made at the suggestion of the referee. We have added an appendix in which we
consider winds with beta-velocity laws, rather than simply constant
velocitie
A spectropolarimetric view on the nature of the peculiar Type I SN 2005hk
We report two spectropolarimetric observations of SN 2005hk, which is a close
copy of the "very peculiar" SN 2002cx, showing low peak luminosity, slow
decline, high ionization near peak and an unusually low expansion velocity of
only about 7,000 km s^-1. Further to the data presented by Chornock et al.,
(2006), at -4 days before maximum, we present data of this object taken on 9
November 2005 (near maximum) and 23 November (+ two weeks) that show the
continuum and most of the spectral lines to be polarized at levels of about
0.2-0.3%. At both epochs the data corresponds to the Spectropolarimetric Type
D1. The general low level of line polarization suggests that the line forming
regions for most species observed in the spectrum have a similar shape to that
of the photosphere, which deviates from a spherical symmetry by <10%. In
comparison with spectropolarimetry of Type Ia and Core-collapse SNe at similar
epochs, we find that the properties of SN 2005hk are most similar to those of
Type Ia SNe. In particular, we find the low levels of continuum and line
polarization to indicate that the explosion mechanism is approximately
spherical, with homogeneous ejecta (unlike the chemically segregated ejecta of
CCSNe). We discuss the possibility that SN 2005hk was the result of the pure
deflagration of a white dwarf and note the issues concerning this
interpretation.Comment: ApJ accepted, uses emulateapj, 16 pages, 10 figures, figures 3 and 4
update
Spectropolarimetry of the Type Ia SN 2007sr Two Months After Maximum Light
We present late time spectropolarimetric observations of SN 2007sr, obtained
with the VLT telescope at ESO Paranal Observatory when the object was 63 days
after maximum light. The late time spectrum displays strong line polarization
in the CaII absorption features. SN 2007sr adds to the case of some normal Type
Ia SNe that show high line polarization or repolarization at late times, a fact
that might be connected with the presence of high velocity features at early
times
X-ray Line Emission from the Hot Stellar Wind of theta 1 Ori C
We present a first emission line analysis of a high resolution X-ray spectrum
of the stellar wind of theta 1 Ori C obtained with the High Energy Transmission
grating Spectrometer onboard the Chandra X-ray Observatory. The spectra are
resolved into a large number of emission lines from H- and He-like O, Ne, Mg,
Si, S, Ar and Fe ions. The He-like Fe XXV and Li-like Fe XXIV appear quite
strong indicating very hot emitting regions. From H/He flux ratios, as well as
from Fe He/Li emission measure ratios we deduce temperatures ranging from 0.5
to 6.1 x 10^7 K. The He-triplets are very sensitive to density as well. At
these temperatures the relative strengths of the intercombination and forbidden
lines indicate electron densities well above 10^12 cm^-3. The lines appear
significantly broadened from which we deduce a mean velocity of 770 km/s with a
spread between 400 and 2000 km/s. Along with results of the deduced emission
measure we conclude that the X-ray emission could originate in dense and hot
regions with a characteristic size of less then 4 x 10^10 cm.Comment: 4 pages, 3 figure
Properties of mm galaxies: Constraints from K-band blank fields
We have used the IRAM Plateau de Bure mm interferometer to locate with
subarcsecond accuracy the dust emission of three of the brightest 1.2mm sources
in the NTT Deep Field (NDF) selected from our 1.2mm MAMBO survey at the IRAM
30m telescope. We combine these results with deep B to K imaging and VLA
interferometry. Strikingly, none of the three accurately located mm galaxies
MMJ120546-0741.5, MMJ120539-0745.4, and MMJ120517-0743.1 has a K-band
counterpart down to the faint limit of K>21.9. This implies that these three
galaxies are either extremely obscured and/or are at very high redshifts
(z>~4). We combine our results with literature data for 11 more (sub)mm
galaxies that are identified with similar reliability. In terms of their K-band
properties, the sample divides into three roughly equal groups: (i) undetected
to K~22, (ii) detected in the near-infrared but not the optical and (iii)
detected in the optical with the possibility of optical follow-up spectroscopy.
We find a trend in this sample between near-infrared to submm and submm to
radio spectral indices, which in comparison to spectral energy distributions
(SEDs) of low redshift infrared luminous galaxies suggests that the most
plausible primary factor causing the extreme near-infrared faintness of our
objects is their high redshift. We show that the near-infrared to radio SEDs of
the sample are inconsistent with SEDs that resemble local far-infrared cool
galaxies with moderate luminosities, which were proposed in some models of the
submm sky. We briefly discuss the implications of the results for our
understanding of galaxy formation.Comment: aastex, 5 figures. Accepted by Ap
Sport and the local economy: the role of stadia in regenerating commercial property
The use of sports stadia for economic development and regeneration has gained increasingly credibility in recent years, both academically and in terms of UK urban policy. However, evidence to support the effectiveness of stadia for these purposes is highly variable. This paper uses a comparative case study of the Millennium Stadium and the City of Manchester Stadium to examine the effects of stadia development on the commercial property market, an area of research that has received little attention in the literature. It uses the expert opinion of professionals working in real estate, together with the experience of key stakeholders in Manchester and Cardiff to provide empirical evidence that stadia can create tangible and intangible impacts on the commercial property market, but that these are variable between different sectors. It concludes by arguing the need for further research on the role of stadia in the regeneration process if the impacts of these developments are to be maximised in the future.</p
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