83 research outputs found
Contact Binary Variables as X-ray Sources
We present cross-identification of archived X-ray point sources with W UMa
variable stars found in the All-Sky Automated Survey (ASAS). In a surveyed sky
area of 300 square degrees of ASAS, 36 W UMa stars have been found associated
with X-ray emission. We compute the distances of these W UMa systems and hence
their X-ray luminosities. Our data support the "supersaturation" phenomenon
seen in these fast rotators, namely that the faster a W UMa star rotates, the
weaker its X-ray luminosity.Comment: 10 pages, 2 figures, 1 table; submitted to A
Masses and Luminosities of O and B - type stars and red super giants
Massive stars are of interest as progenitors of super novae, i.e. neutron
stars and black holes, which can be sources of gravitational waves. Recent
population synthesis models can predict neutron star and gravitational wave
observations but deal with a fixed super nova rate or an assumed initial mass
function for the population of massive stars. Here we investigate those massive
stars, which are supernova progenitors, i.e. with O and early B type stars, and
also all super giants within 3kpc. We restrict our sample to those massive
stars detected both in 2MASS and observed by Hipparcos, i.e. only those stars
with parallax and precise photometry. To determine the luminosities we
calculated the extinctions from published multi-colour photometry, spectral
types, luminosity class, all corrected for multiplicity and recently revised
Hipparcos distances. We use luminosities and temperatures to estimate the
masses and ages of these stars using different models from different authors.
Having estimated the luminosities of all our stars within 3kpc, in particular
for all O- and early B-type stars, we have determined the median and mean
luminosities for all spectral types for luminosity classes I, III, and V. Our
luminosity values for super giants deviate from earlier results: Previous work
generally overestimates distances and luminosities compared to our data, this
is likely due to Hipparcos parallaxes (generally more accurate and larger than
previous ground-based data) and the fact that many massive stars have recently
been resolved into multiples of lower masses and luminosities. From
luminosities and effective temperatures we derived masses and ages using mass
tracks and isochrones from different authors. From masses and ages we estimated
lifetimes and derived a lower limit for the supernova rate of ~20 events/Myr
averaged over the next 10 Myrs within 600 pc from the sun. These data are then
used to search for areas in the sky with higher likelihood for a supernova or
gravitational wave event (like OB associations).Comment: 13 pages, 13 figures, submitted to AN Dec 12 200
Orbit and spin evolution of the synchronous binary stars on the main sequence phase
The sets of the synchronous equations are derived from the sets of
non-synchronous equations The analytical solutions are given by solving the set
of differential equations. The results of the evolutionary tendency of the
orbit-spin are that the semi-major axis shrinks gradually with time: the
orbital eccentricity dereacses gradually with time until the orbital
circularization; the orbital period shortens gradually with time and the
rotational angular velocity of primary component speed up with time gradually
before the orbit-rotation achieved the circularization The theoretical results
are applied to evolution of the orbit and spin of synchronous binary stars
Algol A, B on the main sequence phase The circularization time and life time
(age) and the evolutional numerical solutions of orbit and spin when
circularization time are estimeted for Algol A, B. The results are discussed
and concluded.Comment: 8 pages, accepted for publication in RA
A study of the interacting binary V 393 Scorpii
We present high resolution J-band spectroscopy of V 393 Sco obtained with the
CRIRES at the ESO Paranal Observatory along with a discussion of archival IUE
spectra and published broad band magnitudes. The best fit to the spectral
energy distribution outside eclipse gives = 19000 500 for the
gainer, = 7250 300 for the donor, = 0.13 0.02
mag. and a distance of = 523 60 pc, although circumstellar material
was not considered in the fit. We argue that V 393 Sco is not a member of the
open cluster M7. The shape of the He I 1083 nm line shows orbital modulations
that can be interpreted in terms of an optically thick pseudo-photosphere
mimicking a hot B-type star and relatively large equatorial mass loss through
the Lagrangian L3 point during long cycle minimum. IUE spectra show several
(usually asymmetric) absorption lines from highly ionized metals and a narrow
L emission core on a broad absorption profile. The overall behavior of
these lines suggests the existence of a wind at intermediate latitudes. From
the analysis of the radial velocities we find = 0.24 0.02
and a mass function of = 4.76 0.24 M. Our observations favor
equatorial mass loss rather than high latitude outflows as the cause for the
long variability.Comment: 13 pages, 14 figures, 7 tables. Accepted for publication in MNRAS,
main journa
The first light-curve analysis of eclipsing binaries observed by the INTEGRAL/OMC
Three Algol-type binaries in Cygnus constellation were selected for an
analysis from a huge database of observations made by the INTEGRAL/OMC camera.
These data were processed and analyzed, resulting in a first light-curve study
of these neglected eclipsing binaries. The temperatures of the primary
components range from 9500 K to 10500 K and the inclinations are circa 73deg
(for PV Cyg and V1011 Cyg), while almost 90deg for V822 Cyg. All of them seem
to be main-sequence stars, well within their critical Roche lobes.
Nevertheless, further detailed analyses are still needed.Comment: 6 pages, 4 figures, 2 tables, published in New As
Period changes in six semi-detached Algol-type binaries
Six semi-detached Algol-type binaries lacking a period analysis were chosen
to test for a presence of a third body. The O-C diagrams of these binaries were
analyzed with the least-squares method by using all available times of minima.
Also fourteen new minima, obtained from our observations, were included in the
present research. The light-time effect was adopted as a main factor for the
detailed description of the long-term period changes. Third bodies were found
with orbital periods from 46 up to 84 years, and eccentricities from 0.0 to
0.78 for the selected binaries. The mass functions and the minimal masses of
such bodies were also calculated.Comment: 14 pages, 8 figure
Orbital and physical parameters of eclipsing binaries from the ASAS catalogue -- I. A sample of systems with components' masses between 1 and 2 M
We derive the absolute physical and orbital parameters for a sample of 18
detached eclipsing binaries from the \emph{All Sky Automated Survey} (ASAS)
database based on the available photometry and our own radial velocity
measurements. The radial velocities (RVs) are computed using spectra we
collected with the 3.9-m Anglo-Australian Telescope and its \emph{University
College London Echelle Spectrograph} and the 1.9-m SAAO Radcliffe telescope and
its \emph{Grating Instrument for Radiation Analysis with a Fibre Fed Echelle}.
In order to obtain as precise RVs as possible, most of the systems were
observed with an iodine cell available at the AAT/UCLES and/or analyzed using
the two-dimensional cross-correlation technique (TODCOR). The RVs were measured
with TODCOR using synthetic template spectra as references. However, for two
objects we used our own approach to the tomographic disentangling of the binary
spectra to provide observed template spectra for the RV measurements and to
improve the RV precision even more. For one of these binaries, AI Phe, we were
able to the obtain an orbital solution with an RV of 62 and 24 m s
for the primary and secondary respectively. For this system, the precision in
is 0.08%. For the analysis, we used the photometry available in
the ASAS database. We combined the RV and light curves using PHOEBE and JKTEBOP
codes to obtain the absolute physical parameters of the systems. Having precise
RVs we were able to reach 0.2 % precision (or better) in masses in
several cases but in radii, due to the limited precision of the ASAS
photometry, we were able to reach a precision of only 1% in one case and 3-5 %
in a few more cases. For the majority of our objects, the orbital and physical
analysis is presented for the first time.Comment: 16 pages, 2 figures, 6 tables in the main text, 1 table in appendix,
to appear in MNRA
ASAS Light Curves of Intermediate Mass Eclipsing Binaries and the Parameters of HI Mon
We present a catalog of 56 candidate intermediate mass eclipsing binary
systems extracted from the 3rd data release of the All Sky Automated Survey. We
gather pertinent observational data and derive orbital properties, including
ephemerides, for these systems as a prelude to anticipated spectroscopic
observations. We find that 37 of the 56, or ~66% of the systems are not
identified in the Simbad Astronomical Database as known binaries. As a specific
example, we show spectroscopic data obtained for the system HI Mon (B0 V + B0.5
V) observed at key orbital phases based on the computed ephemeris, and we
present a combined spectroscopic and photometric solution for the system and
give stellar parameters for each component.Comment: 83 pages, 63 figure
Trądzik chorobą zapalną, a nie bakteryjną
Trądzik zwyczajny to jedna z najczęściej występujących chorób skóry. Jest uznawany za chorobę przewlekłą, dotyczącą jednostki włosowołojowej. Patofizjologia zmian trądzikowych jest złożona; znaczenie mają: zwiększone wydzielanie sebum, nadmierne rogowacenie mieszków włosowych, kolonizacja Propionibacterium acnes w gruczołach łojowych oraz stan zapalny. Obraz chorobowy jest różnorodny i zależy od nasilenia zmian skórnych. Wśród ciężkich postaci trądziku wyróżniamy ciężki trądzik grudkowo-krostkowy, guzkowy, skupiony i piorunujący. Choroba oraz jej następstwa mogą prowadzić do zaburzeń psychicznych.W pracy przedstawiono przypadek 14-letniego chłopca z trądzikiem skupionym, u którego wystąpiło zaostrzenie zmian trądzikowych podczas terapii izotretinoiną doustną. Potraktowanie choroby jako dermatozy bakteryjnej doprowadziło do niepotrzebnej interwencji chirurgicznej, która przyczyniła się do powstania dodatkowych blizn na skórze twarzy.Zwrócono uwagę na znaczenie mikrobiomu skóry, przedstawiono możliwości terapeutyczne leczenia trądziku skupionego i postępowanie w przypadku zaostrzenia się zmian trądzikowych podczas leczenia izotretinoiną
Period changes in six contact binaries: WZ And, V803 Aql, DF Hya, PY Lyr, FZ Ori, and AH Tau
Six contact binaries lacking a period analysis have been chosen to search for
the presence of a third body. The O-C diagrams of these binaries were analyzed
with the least-squares method by using all available times of minima. Ten new
minima times, obtained from our observations, were included in the present
research. The Light-Time Effect was adopted for the first time as the main
cause for the detailed description of the long-term period changes. Third
bodies were found with orbital periods from 49 up to 100 years, and
eccentricities from 0.0 to 0.56 for the selected binaries. In one case (WZ
And), a fourth-body LITE variation was also applied. The mass functions and the
minimal masses of such bodies were also calculated and a possible angular
separation and magnitude differences were discussed for a prospective
interferometric discovery of these bodies.Comment: 7 pages, 8 figures, 2009 New Astronomy 14, 12
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