1,808 research outputs found
Comprehensive analysis of RGU photometry in the direction to M5
The RGU-photographic investigation of an intermediate latitude field in the
direction to the Galactic center is presented. 164 extra-galactic objects,
identified by comparison of Minnesota and Basel charts, are excluded from the
program. Also, a region with size 0.104 square-degrees, contaminated by cluster
(M5) stars and affected by background light of the bright star HD 136202 is
omitted. Contrary to previous investigations, a reddening of ,
corresponding to E(G-R)=0.07 mag is adopted. The separation of dwarfs and
evolved stars is carried out by an empirical method, already applied in some of
our works. A new calibration for the metallicity determination is used for
dwarfs, while the absolute magnitude determination for stars of all categories
is performed using the procedures given in the literature. There is good
agreement between the observed logarithmic space density histograms and the
galactic model gradients. Also, the local luminosity function agrees with
Gliese's (1969) and Hipparcos' (Jahreiss & Wielen 1997) luminosity functions,
for stars with mag. For giants, we obtained two different local
space densities from comparison with two Galactic models, i.e. ,
close to that of Gliese (1969), and . A metallicity gradient,
dex/kpc, is detected for dwarfs (only) with absolute
magnitudes , corresponding to a spectral type interval F5-K0.Comment: 17 pages, including 13 figures and 3 tables, accepted for publication
in PAS
New colour-transformations for the Sloan photometry and revised metallicity calibration and equations for photometric parallax estimation
We evaluated new colour-transformations for the Sloan photometry by 224
standards and used them to revise both the equations for photometric parallax
estimation and metallicity calibration cited by Karaali et al. (2003). This
process improves the metallicity and absolute magnitude estimations by
[Fe/H]<=0.3 dex and M^{H}_{g} <= 0.1 mag respectively. There is a high
correlation for metallicities and absolute magnitudes derived for two systems,
UBV and Sloan, by means of the revised calibrations.Comment: 11 pages, including 7 figures and 2 tables, accepted for publication
in PAS
Volume limited dependent Galactic model parameters
We estimated 34 sets of Galactic model parameters for three intermediate
latitude fields with Galactic longitudes l=60, l=90, and l=180, and we
discussed their dependence on the volume. Also, we confirmed the variation of
these parameters with absolute magnitude and Galactic longitude. The star
samples in two fields are restricted with bright and unit absolute magnitude
intervals, (4,5], and (5,6], whereas for the third field a larger absolute
magnitude interval is adopted, (4,10]. The limiting apparent magnitudes of star
samples are g=15 and g=22.5 mag which provide space densities within distances
in the line of sight 0.9 and 25 kpc. The Galactic model parameters for the thin
disc are not volume dependent. However, the ones for thick disc and halo do
show spectacular trends in their variations with volume, except for the
scalelength of the thick disc. The local space density of the thick disc
increases, whereas the scaleheight of the same Galactic component decreases
monotonically. However, both model parameters approach asymptotic values at
large distances. The axial ratio of the halo increases abruptly for the volumes
where thick disc is dominant, whereas it approaches an asymptotic value
gradually for larger volumes, indicating a continuous transition from disclike
structure to a spherical one at the outermost region of the Galaxy. The
variation of the Galactic model parameters with absolute magnitude can be
explained by their dependence on the stellar luminosity, whereas the variation
with volume and Galactic longitude at short distances is a bias in analysis.Comment: 12 pages, including 8 figures and 5 tables, accepted for publication
in PAS
Transformations between the theoretical and observational planes in the HST-NICMOS and WFPC2 photometric systems
Color-temperature relations and bolometric corrections in the HST-NICMOS
F1110W, F160W and F222M and in the WFPC2 F439W, F555W and F814W photometric
systems, using two different sets of model atmospheres, have been derived. This
database of homogeneous, self-consistent transformations between the
theoretical and observational planes also allows combinations of visual and
infrared quantities, without any further transformation between the two
different photometric systems. The behavior of the inferred quantities with
varying the stellar parameters, the adopted model atmospheres and the
instrumental configurations are investigated. Suitable relations to transform
colors and bolometric corrections from HST to ground-based photometric systems
are also provided.Comment: 22 pages, 14 figure
Comprehensive Analysis of RGU Photometry in the Direction to M5
The RGU-photographic investigation of an intermediate latitude field in the direction to the Galactic centre is presented. 164 extra-galactic objects, identified by comparison of Minnesota and Basel charts, are excluded from the program. Also, a region with size 0.104 square-degrees, contaminated by cluster (M5) stars and affected by background light of the bright star HD 136202 is omitted. Contrary to previous investigations, a reddening of E(B - V) = 0.046, corresponding to E(G - R) = 0.07 mag is adopted. The separation of dwarfs and evolved stars is carried out by an empirical method, already applied in some of our works. A new calibration for the metallicity determination is used for dwarfs, while the absolute magnitude determination for stars of all categories is performed using the procedures given in the literature. There is good agreement between the observed logarithmic space density histograms and the galactic model gradients. Also, the local luminosity function agrees with Gliese's (1969) and Hipparcos (Jahreiss & Wielen 1997) luminosity functions, for stars with 2 < M(G) ≤ 8 mag. For giants, we obtained two different local space densities from comparison with two Galactic models, i.e. D*(0) = 6.63, close to that of Gliese (1969), and D*(0) = 6.79. A metallicity gradient, d[Fe/H]/dz = -0.20 dex kpc-1, is detected for dwarfs (only) with absolute magnitudes 4 < M(G) ≤ 6, corresponding to a spectral type interval F5-K
Placement of a temporary pacemaker electrode through a persistent left superior vena cava
Perioperative temporary pacing was needed in a patient with congenital skeletal malformations and a cardiac conduction disturbance with incomplete trifascicular block. We report the successful placement of the pacemaker electrode through a persistent left superior vena cava (SVC
Stable Isotope Event Markers Near the Permo-Triassic Boundary in the Karavanke Mountains (Slovenia)
Stable isotope analyses of carbonates and organic matter from the Permo-Triassic boundary section in the Karavanke Mountains, Slovenia, indicate a further example of the “light carbon” event across the boundary. In this section the changes in carbon isotope values were a direct result of the culmination of the marine regression and associated events at the end of the Permian, which caused a drop in primary productivity, as well as related local environmental changes, with no evidence of any considerable diagenetic overprint
New metallicity calibration down to [Fe/H] = -2.75 dex
88 dwarfs, covering the colour index interval 0.37 <(B-V)o <= 1.07 mag, with
metallicities -2.70 <= [Fe/H] <= +0.26 dex have been taken from three different
sources for new metallicity calibration. The catalogue of Cayrel de Stroble et
al. (2001) which includes 65% of the stars in our sample supplies detailed
information on abundances for stars with determination based on high resolution
spectroscopy. 77 stars which supplies at least one of the following conditions
have been used as "corner stones" for constructing the new calibration: (i) the
parallax is larger than 10 mas (distance relative to the Sun less than 100 pc)
and the galactic latitude is absolutely higher than 30 degrees, (ii) the
parallax is rather large, if the galactic latitude is absolutely low and vice
versa. Contrary to the previous investigations, a third-degree polynomial
fitted for the new calibration: [Fe/H] = 0.10-2.76d-24.04d^2+30.00d^3. The
coefficients were evaluated by the least-square method, without regarding the
metallicity of Hyades. However, the constant term is in the range of
metallicity determined for this cluster i.e.: 0.08 <= [Fe/H] <= 0.11 dex. The
mean deviation and the mean error in our work are equal to those of Carney
(1979), for [Fe/H] >= -1.75 dex where Carney's calibration is valid.Comment: 22 pages, 5 figures. accepted for PASA, Vol 20, No
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