33,721 research outputs found

    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

    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

    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

    Brown dwarfs in the Hyades and beyond?

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    We have used both the Low-Resolution Imaging Spectrograph and the HIRES echelle spectrograph on the Keck telescopes to obtain spectra of twelve candidate members of the Hyades cluster identified by Leggett and Hawkins (1988, 1989). All of the objects are chromospherically-active, late-type M-dwarfs, with Hα\alpha equivalent widths varying from 1 to 30\AA. Based on our measured radial velocities, the level of stellar activity and other spectroscopic features, only one of the twelve stars has properties consistent with cluster membership. We consider how this result affects estimates of the luminosity and mass function of the Hyades cluster. Five of the eleven field stars have weak K I 7665/7699\AA and CaH absorption as compared with M-dwarf standards of the same spectral type, suggesting a lower surface gravity. Two of these sources, LH0416+14 and LH0419+15, exhibit significant lithium 6708 \AA absorption. Based partly on parallax measurements by the US Naval Observatory (Harris et al, 1998), we identify all five as likely to be young, pre-main sequence objects in or near the Taurus-Auriga association at distances of between 150 and 250 parsecs. A comparison with theoretical models of pre-main sequence stars indicates masses of less than 0.05 M_\odot.Comment: to appear in AJ, January 1999; 34 pages, (Latex format), including 10 embedded postscript figures and two table
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