33,721 research outputs found
The Eurovision St Andrews collection of photographs
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
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 K. This is consistent with the available (R-I) and (I-K)
colours. If the parallax measured by Hawkins et al is correct, then the
implication is that D04 has a radius of , 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. We suggest that an equally valid
interpretation of the data is that D04 is a VB8 analogue at a distance of
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
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
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?
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 H 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.Comment: to appear in AJ, January 1999; 34 pages, (Latex format), including 10
embedded postscript figures and two table
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