455 research outputs found
AGAPEROS: Searching for variable stars in the LMC Bar with the Pixel Method. I. Detection, astrometry and cross-identification
We extend the work developed in previous papers on microlensing with a
selection of variable stars. We use the Pixel Method to select variable stars
on a set of 2.5 x 10**6 pixel light curves in the LMC Bar presented elsewhere.
The previous treatment was done in order to optimise the detection of long
timescale variations (larger than a few days) and we further optimise our
analysis for the selection of Long Timescale and Long Period Variables
(LT&LPV). We choose to perform a selection of variable objects as comprehensive
as possible, independent of periodicity and of their position on the colour
magnitude diagram. We detail the different thresholds successively applied to
the light curves, which allow to produce a catalogue of 632 variable objects.
We present a table with the coordinate of each variable, its EROS magnitudes at
one epoch and an indicator of blending in both colours, together with a finding
chart.
A cross-correlation with various catalogues shows that 90% of those variable
objects were undetected before, thus enlarging the sample of LT&LPV previously
known in this area by a factor of 10. Due to the limitations of both the Pixel
Method and the data set, additional data -- namely a longer baseline and near
infrared photometry -- are required to further characterise these variable
stars, as will be addressed in subsequent papers.Comment: 11 pages with 10 figure
The Role of Pressure in GMC Formation II: The H_2 - Pressure Relation
We show that the ratio of molecular to atomic gas in galaxies is determined
by hydrostatic pressure and that the relation between the two is nearly linear.
The pressure relation is shown to be good over three orders of magnitude for 14
galaxies including dwarfs, HI-rich, and H_2-rich galaxies as well as the Milky
Way. The sample spans a factor of five in mean metallicity. The rms scatter of
individual points of the relation is only about a factor of two for all the
galaxies, though some show much more scatter than others. Using these results,
we propose a modified star formation prescription based on pressure determining
the degree to which the ISM is molecular. The formulation is different in high
and low pressure regimes defined by whether the gas is primarily atomic or
primarily molecular. This formulation can be implemented in simulations and
provides a more appropriate treatment of the outer regions of spiral galaxies
and molecule-poor systems such as dwarf irregulars and damped Lyman-alpha
systems.Comment: 14 pages, 7 figures, Accepted to the Astrophysical Journa
Cohort study of an outbreak of viral gastroenteritis in a nursing home for elderly, Majorca, Spain, February 2008.
An outbreak of acute gastroenteritis occurred in a nursing home for elderly in Majorca between 4 and 23 February 2008. To know its aetiology and mechanism of transmission a retrospective cohort study was conducted with a fixed cohort including 146 people (96 residents and 50 employees). The data were collected from clinical histories and through a survey by questionnaire. In total 71 cases were identified (53 residents, 18 employees), corresponding to an overall attack rate (AR) of 48.6%
Survey for Emission-Line Galaxies: Universidad Complutense de Madrid List 3
A new low-dispersion objective-prism search for low-redshift (z<0.045)
emission-line galaxies (ELG) has been carried out by the Universidad
Complutense de Madrid with the Schmidt Telescope at the Calar-Alto Observatory.
This is a continuation of the UCM Survey, which was performed by visual
selection of candidates in photographic plates via the presence of the
Halpha+[NII]6584 blend in emission. In this new list we have applied an
automatic procedure, fully developed by us, for selecting and analyzing the ELG
candidates on the digitized images obtained with the MAMA machine. The analyzed
region of the sky covers 189 square degrees in nine fields near R.A.=14h & 17h,
Dec=25 deg. The final sample contains 113 candidates. Special effort has been
made to obtain a large amount of information directly from our uncalibrated
plates by using several external calibrations. The parameters obtained for the
ELG candidates allow for the study of the statistical properties for the
sample.Comment: 13 pages, 18 PostScript figures, 6 JPEG figures, Table 2 corrected.
Accepted for publication in Astrophysical Journal Supplements, also available
at http://www.ucm.es/info/Astrof/opera/LIST3_ApJS99
Recommended from our members
NACA Research Memorandums
From Summary: "The trajectories of waterdrops in air flowing over airfoils are determined for three airfoil-angle-of-attack combinations using the differential analyzer to solve the differential equations of motion of the waterdrops. From these trajectories the rate of water impingement, the area of impingement, and the distribution of impingement are determined as functions of two dimensionless moduli. Comparisons are made of the rate of water impingement on these airfoils and the rate of water impingement on cylinders.
Motivic Serre invariants, ramification, and the analytic Milnor fiber
We show how formal and rigid geometry can be used in the theory of complex
singularities, and in particular in the study of the Milnor fibration and the
motivic zeta function. We introduce the so-called analytic Milnor fiber
associated to the germ of a morphism f from a smooth complex algebraic variety
X to the affine line. This analytic Milnor fiber is a smooth rigid variety over
the field of Laurent series C((t)). Its etale cohomology coincides with the
singular cohomology of the classical topological Milnor fiber of f; the
monodromy transformation is given by the Galois action. Moreover, the points on
the analytic Milnor fiber are closely related to the motivic zeta function of
f, and the arc space of X.
We show how the motivic zeta function can be recovered as some kind of Weil
zeta function of the formal completion of X along the special fiber of f, and
we establish a corresponding Grothendieck trace formula, which relates, in
particular, the rational points on the analytic Milnor fiber over finite
extensions of C((t)), to the Galois action on its etale cohomology.
The general observation is that the arithmetic properties of the analytic
Milnor fiber reflect the structure of the singularity of the germ f.Comment: Some minor errors corrected. The original publication is available at
http://www.springerlink.co
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