28,394 research outputs found

    Green Grass, High Cotton: Reflections on the Evolution of the Journal of Advertising

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    This article reflects on my time as the fifth editor of the Journal of Advertising, makes observations about the evolution of scholarship in the Journal over the past decades, offers suggestions for how JA might advance in the coming years, and provides some “words of wisdom” to advertising researchers. Because it is the first in an invited article series of editor reflections, a bit of historical context is provided

    The Eurovision St Andrews collection of photographs

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    This report describes the Eurovision image collection compiled for the ImageCLEF (Cross Language Evaluation Forum) evaluation exercise. The image collection consists of around 30,000 photographs from the collection provided by the University of St Andrews Library. The construction and composition of this unique image collection are described, together with the necessary information to obtain and use the image collection

    Optical spectroscopy of a brown dwarf candidate

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    We have used the Low-Resolution Imaging Spectrograph on the Keck II telescope to observe the brown dwarf candidate D04 (Hawkins et al, 1998). The spectrum matches that of a spectral-type M7 dwarf, implying a photospheric temperature of ≈2600\approx 2600K. This is consistent with the available (R-I)C_C and (I-K) colours. If the parallax measured by Hawkins et al is correct, then the implication is that D04 has a radius of ∌0.035R⊙\sim 0.035 R_\odot, or one-third that of Jupiter. This contradicts the predictions made by current stellar models that electron degeneracy leads to nearly constant radii for stars and brown dwarfs at masses below 0.1 M⊙_\odot. We suggest that an equally valid interpretation of the data is that D04 is a VB8 analogue at a distance of ≈150\approx 150 parsecs.Comment: to appear in MNRAS, pink pages; 6 pages with 1 jpg, 1 postscript figur

    High-resolution Spectra of Very Low-Mass Stars

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    We present the results of high-resolution (1-0.4A) optical spectroscopy of a sample of very low-mass stars. These data are used to examine the kinematics of the stars at the bottom of the hydrogen-burning main sequence. No evidence is found for a significant difference between the kinematics of the stars in our sample with I-K > 3.5 (MBol > 12.8) and those of more massive M-dwarfs (MBol = 7-10). A spectral atlas at high (0.4A) resolution for M8-M9+ stars is provided, and the equivalent widths of CsI, RbI and Halpha lines present in our spectra are examined. We analyse our data to search for the presence of rapid rotation, and find that the brown dwarf LP 944-20 is a member of the class of ``inactive, rapid rotators''. Such objects seem to be common at and below the hydrogen burning main sequence. It seems that in low-mass/low-temperature dwarf objects either the mechanism which heats the chromosphere, or the mechanism which generates magnetic fields, is greatly suppressed.Comment: 19 pages, 12 figure files. MNRAS style file. Accepted for publication in MNRAS, August 199

    Constraining the Star Formation Histories of Spiral Bulges

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    Long-slit spectroscopic observations of line-strengths and kinematics made along the minor axes of four spiral bulges are reported. Comparisons are made between central line-strengths in spiral bulges and those in other morphological types. The bulges are found to have central line-strengths comparable with those of single stellar populations (SSPs) of approximately solar abundance or above. Negative radial gradients are observed in line-strengths, similar to those in elliptical galaxies. The bulge data are consistent with correlations between Mg2, and central velocity dispersion observed in elliptical galaxiess. In contrast to elliptical galaxies, central line-strengths lie within the loci defining the range of and Mg2 achieved by Worthey's (1994) solar abundance ratio, SSPs. The implication of solar abundance ratios indicates differences in the star formation histories of spiral bulges and elliptical galaxies. A ``single zone with in- fall'' model of galactic chemical evolution, using Worthey's (1994) SSPs, is used to constrain possible star formation histories in our sample. We show that , Mg2 and Hbeta line-strengths observed in these bulges cannot be reproduced using primordial collapse models of formation but can be reproduced by models with extended in-fall of gas and star formation (2-17 Gyr) in the region modelled. One galaxy (NGC 5689) shows a central population with luminosity weighted average age of ~5 Gyr, supporting the idea of extended star formation. Kinematic substructure, possibly associated with a central spike in metallicity, is observed at the centre of the Sa galaxy NGC 3623.Comment: 14 pages. MNRAS latex file. Accepted for publication in MNRA
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