107 research outputs found
The eclipse of Epsilon Aurigae visible spectroscopy and ultraviolet activity
The preliminary results of the study of several high resolution spectrograms (lambda 3500 - lambda 7000 A), obtained at the Haute Provence Observatory (OHP) in France, at different epochs before, during and after the eclipse are reported. Some of these spectrograms are compared with corresponding IUE high resolution observations, in order to study the effects of the intrinsic UV activity, towards the longer wavelengths
The 2003 eclipse of EE Cep is coming. A review of past eclipses
EE Cep is an eclipsing binary with a period of 5.6 years. The next eclipse
will occur soon, in May-June 2003, and all available past eclipses were
collected and briefly analysed. EE Cep shows very large changes of the shape
and the depth of minima during different eclipses, however it is possible to
single out some persistent features. The analysis suggests that the eclipsing
body should be a long object surrounded by an extended semi-transparent
envelope. As an explanation, a model of a precessing optically thick disc,
inclined to the plane of the binary orbit, is invoked. The changes of its
spatial orientation, which is defined by the inclination of the disc and the
tilt, induced most probably by precession of the disc spin axis with a period
of about 50 years, produce strange photometric behaviour of this star. The
H_alpha emission, and possibly the NaI absorptions, show significant changes
during several months outside of the eclipse phase.Comment: 7 pages, 7 figures, LaTeX2e, accepted by A&
2D Monte-Carlo Radiative transfer modeling of the disk shaped secondary of Epsilon Aurigae
We present two dimensional Monte-Carlo radiative transfer models for the disk
of the eclipsing binary Aur by fitting its spectral energy
distribution from optical to the far-IR wavelengths. We also report new
observations of Aur made by AKARI in its five mid and far-IR
photometric bands and were used to construct our SED. The disk is optically
thick and has flared disk geometry containing gas and dust with a gas to dust
mass ratio of 100. We have taken the primary of the binary to be a F0Iae-type
post-AGB star and the disk is heated by a B5V hot star with a temperature of
15,000 K at the center of the disk. We take the radius of the disk to be 3.8 AU
for our models as constrained from the IR interferometric imaging observations
of the eclipsing disk. Our models imply that the disk contains grains which are
much bigger than the ISM grains (grain sizes 10 to 100). The grain
chemistry of the disk is carbonaceous and our models show that silicate and ISM
dust chemistry do not reproduce the slope of the observed SED in the mid-IR to
far-IR regions. This implies that the formation of the disk shaped secondary in
Aur system could be the result of accretion of matter and or mass
transfer from the primary which is now a F0Iae post-AGB star. It is not a
proto-planetary disk. The disk is seen nearly edge on with an inclination angle
larger than 85. We propose from our radiative transfer modeling that the
disk is not solid and have a void of 2AU radius at the center within which no
grains are present making the region nearly transparent. The disk is not
massive, its mass is derived to be less than 0.005M.Comment: 27 pages, 5 figures, 2 table
The PROVENT-C19 registry: A study protocol for international multicenter SIAARTI registry on the use of prone positioning in mechanically ventilated patients with COVID-19 ARDS
Background The worldwide use of prone position (PP) for invasively ventilated patients with COVID-19 is progressively increasing from the first pandemic wave in everyday clinical practice. Among the suggested treatments for the management of ARDS patients, PP was recommended in the Surviving Sepsis Campaign COVID-19 guidelines as an adjuvant therapy for improving ventilation. In patients with severe classical ARDS, some authors reported that early application of prolonged PP sessions significantly decreases 28-day and 90-day mortality. Methods and analysis Since January 2021, the COVID19 Veneto ICU Network research group has developed and implemented nationally and internationally the "PROVENT-C19 Registry", endorsed by the Italian Society of Anesthesia Analgesia Resuscitation and Intensive Care. . .'(SIAARTI). The PROVENT-C19 Registry wishes to describe 1. The real clinical practice on the use of PP in COVID-19 patients during the pandemic at a National and International level; and 2. Potential baseline and clinical characteristics that identify subpopulations of invasively ventilated patients with COVID-19 that may improve daily from PP therapy. This web-based registry will provide relevant information on how the database research tools may improve our daily clinical practice. Conclusions This multicenter, prospective registry is the first to identify and characterize the role of PP on clinical outcome in COVID-19 patients. In recent years, data emerging from large registries have been increasingly used to provide real-world evidence on the effectiveness, quality, and safety of a clinical intervention. Indeed observation-based registries could be effective tools aimed at identifying specific clusters of patients within a large study population with widely heterogeneous clinical characteristics. Copyright
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