2,284 research outputs found
Financial History
The considerable renewal of interest in all aspects of financial history over recent years provided one motivation for this new venture. Yet, the foundations for our specialism, which draws from both History and the Social Sciences, especially economics, have been laid by many. Some would point to continuity in our interest from the publication in the 1930s of jubilee banking history volumes, such as those written for British institutions by Gregory, and by Crick and Wadsworth. Further scholarly momentum came from the studies in comparative banking history undertaken by researchers inspired and brought together by Rondo Cameron from the mid-1960s. Upon these footings and others, financial history has since ‘taken off' to address an increasingly wider range of issues. This considerable broadening of the specialism, ironically, almost coincided with the decline and then the eventual demise in 1987 of the Revue Internationale d'Histoire de la Banque, founded in 1968. This is not the place to draw up a balance sheet of that journal, which has played a decisive role. Its demise, however, left a gap. Financial History Review aims not only to take up its cause, but also to widen the scope of publishing in the field - from banking to financial history - in order to offer the fullest possible support for continuing researc
Spectral matching for abundances of 848 stars of the giant branches of the globular cluster {\omega} Centauri
We present the effective temperatures, surface gravities and abundances of
iron, carbon and barium of 848 giant branch stars, of which 557 also have
well-defined nitrogen abundances, of the globular cluster {\omega} Centauri.
This work used photometric sources and lower resolution spectra for this
abundance analysis. Spectral indices were used to estimate the oxygen abundance
of the stars, leading to a determination of whether a particular star was
oxygen-rich or oxygen-poor.
The 557-star subset was analyzed in the context of evolutionary groups, with
four broad groups identified. These groups suggest that there were at least
four main four periods of star formation in the cluster. The exact order of
these star formation events is not yet understood.
These results compare well with those found at higher resolution and show the
value of more extensive lower resolution spectral surveys. They also highlight
the need for large samples of stars when working with a complex object like
{\omega} Cen.Comment: 12 pages, 14 figures, accepted for publication in MNRA
Differential chemical abundance analysis of a 47 Tuc AGB star with respect to Arcturus
This study resolves a discrepancy in the abundance of Zr in the 47 Tucanae
asymptotic giant branch star Lee 2525. This star was observed using the echelle
spectrograph on the 2.3 m telescope at Siding Spring Observatory. The analysis
was undertaken by calibrating Lee 2525 with respect to the standard giant star
Arcturus. This work emphasises the importance of using a standard star with
stellar parameters comparable to the star under analysis rather than a
calibration with respect to the Sun (Koch & McWilliam 2008). Systematic errors
in the analysis process are then minimised due to the similarity in atmospheric
structure between the standard and programme stars. The abundances derived for
Lee 2525 were found to be in general agreement with the Brown & Wallerstein
(1992) values except for Zr. In this study Zr has a similar enhancement
([Zr/Fe] = +0.51 dex) to another light s-process element, Y ([Y/Fe] = +0.53
dex), which reflects current theory regarding the enrichment of s-process
elements by nuclear processes within AGB stars (Busso et al. 2001). This is
contrary to the results of Brown & Wallerstein (1992) where Zr was
under-abundant ([Zr/Fe] = +0.51 dex) and Y was over-abundant ([Y/Fe] = +0.50
dex) with respect to Fe.Comment: 11 pages, 5 figures Accepted for publication in MNRA
Globular Cluster Formation in M82
We present high resolution mid-infrared (mid-IR; 11.7 and 17.65 micron) maps
of the central 400 pc region of the starburst galaxy M82. Seven star forming
clusters are identified which together provide ~ 15% of the total mid-IR
luminosity of the galaxy. Combining the mid-IR data with thermal radio
measurements and near- and mid-IR line emission, we find that these young
stellar clusters have inferred masses and sizes comparable to globular
clusters. At least 20% of the star formation in M82 is found to occur in
super-star clusters.Comment: 12 pages including three color figures; accepted for publication in
Ap
Photometric analysis of Magellanic Cloud R Coronae Borealis Stars in the recovery phase of their declines
This paper presents the initial results of a multi-site photometric programme
to examine the extraordinary behaviour displayed by 18 R Coronae Borealis (RCB)
stars in the Magellanic Clouds (MCs). RCB stars exhibit a unique variability
whereby they undergo rapid declines of up to several magnitudes. These are
thought to be caused by the formation of dust in the stellar environment which
reduces the brightness.
The monitoring programme comprised the collection of UBVRI photometric data
using five telescopes located at three different southern hemisphere longitudes
(Las Campanas Observatory in Chile, Mount Joun University Observatory in New
Zealand, and the Southern African Large Telescope (SALT) in South Africa).
Examination of the data acquired in the V and I filters resulted in the
identification of a total of 18 RCB declines occurring in four stars.
Construction of colour-magnitude diagrams (V vs V-I), during the recovery to
maximum light were undertaken in order to study the unique colour behaviour
associated with the RCB declines. The combined recovery slope for the four
stars was determined to be 3.37+/-0.24, which is similar to the value of
3.1+/-0.1 calculated for galactic RCB stars (Skuljan et al. 2003). These
results may imply that the nature of the dust (i.e. the particle size) is
similar in both our Galaxy and the MCs.Comment: accepted for publication in the Publications of the Astronomical
Society of Australi
AGB subpopulations in the nearby globular cluster NGC 6397
It has been well established that Galactic Globular clusters (GCs) harbour
more than one stellar population, distinguishable by the anti-correlations of
light element abundances (C-N, Na-O, and Mg-Al). These studies have been
extended recently to the asymptotic giant branch (AGB). Here we investigate the
AGB of NGC 6397 for the first time. We have performed an abundance analysis of
high-resolution spectra of 47 RGB and 8 AGB stars, deriving Fe, Na, O, Mg and
Al abundances. We find that NGC 6397 shows no evidence of a deficit in Na-rich
AGB stars, as reported for some other GCs - the subpopulation ratios of the AGB
and RGB in NGC 6397 are identical, within uncertainties. This agrees with
expectations from stellar theory. This GC acts as a control for our earlier
work on the AGB of M 4 (with contrasting results), since the same tools and
methods were used.Comment: 10 pages, 7 figures, 8 tables (2 online-only). Accepted for
publication in MNRA
A new method for the spectroscopic identification of stellar non-radial pulsation modes. II. Mode identification of the Delta Scuti star FG Virginis
We present a mode identification based on new high-resolution time-series
spectra of the non-radially pulsating Delta Scuti star FG~Vir (HD 106384, V =
6.57, A5V). From 2002 February to June a global Delta Scuti Network (DSN)
campaign, utilizing high-resolution spectroscopy and simultaneous photometry
has been conducted for FG~Vir in order to provide a theoretical pulsation
model. In this campaign we have acquired 969 Echelle spectra covering 147 hours
at six observatories. The mode identification was carried out by analyzing line
profile variations by means of the Fourier parameter fit method, where the
observational Fourier parameters across the line are fitted with theoretical
values. This method is especially well suited for determining the azimuthal
order m of non-radial pulsation modes and thus complementary with the method of
Daszynska-Daszkiewicz (2002) which does best at identifying the degree l. 15
frequencies between 9.2 and 33.5 c/d were detected spectroscopically. We
determined the azimuthal order m of 12 modes and constrained their harmonic
degree l. Only modes of low degree (l <= 4) were detected, most of them having
axisymmetric character mainly due to the relatively low projected rotational
velocity of FG Vir. The detected non-axisymmetric modes have azimuthal orders
between -2 and 1. We derived an inclination of 19 degrees, which implies an
equatorial rotational rate of 66 km/s.Comment: 14 pages, 26 figure
Optical Turbulence Measurements and Models for Mount John University Observatory
Site measurements were collected at Mount John University Observatory in 2005
and 2007 using a purpose-built scintillation detection and ranging system.
profiling indicates a weak layer located at 12 - 14 km above sea
level and strong low altitude turbulence extending up to 5 km. During calm
weather conditions, an additional layer was detected at 6 - 8 km above sea
level. profiling suggests that tropopause layer velocities are nominally
12 - 30 m/s, and near-ground velocities range between 2 -- 20 m/s, dependent on
weather. Little seasonal variation was detected in either and
profiles. The average coherence length, , was found to be cm for
the full profile at a wavelength of 589 nm. The average isoplanatic angle,
, was arcsec. The mean turbulence altitude,
, was found to be km above sea level. No average in the
Greenwood frequency, , could be established due to the gaps present in the
\vw\s profiles obtained. A modified Hufnagel-Valley model was developed to
describe the profiles at Mount John, which estimates at 6 cm
and at 0.9 arcsec. A series of models were developed, based
on the Greenwood wind model with an additional peak located at low altitudes.
Using the model and the suggested model for moderate ground
wind speeds, is estimated at 79 Hz.Comment: 14 pages; accepted for publication in PAS
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