Helium Nova on a Very Massive White Dwarf -- A Light Curve Model of V445 Puppis (2000) Revised

V445 Pup (2000) is a unique object identified as a helium nova. Color indexes during the outburst are consistent with those of free-free emission. We present a free-free emission dominated light curve model of V445 Pup on the basis of the optically thick wind theory. Our light curve fitting shows that (1) the white dwarf (WD) mass is very massive (M_WD \gtrsim 1.35 M_\sun), and (2) a half of the accreted matter remains on the WD, both of which suggest that the increasing WD mass. Therefore, V445 Pup is a strong candidate of Type Ia supernova progenitor. The estimated distance to V445 Pup is now consistent with the recent observational suggestions, 3.5 < d < 6.5 kpc. A helium star companion is consistent with the brightness of m_v=14.5 mag just before the outburst, if it is a little bit evolved hot (\log T (K) \gtrsim 4.5) star with the mass of M_He \gtrsim 0.8 M_\sun. We then emphasize importance of observations in the near future quiescent phase after the thick circumstellar dust dissipates away, especially its color and magnitude to specify the nature of the companion star. We have also calculated helium ignition masses for helium shell flashes against various helium accretion rates and discussed the recurrence period of helium novae.Comment: 8 pages including 12 figures, to appear in Ap

Dust rings and filaments around the isolated young star V1331 Cygni

We characterize the small and large scale environment of the young star V1331 Cygni with high resolution HST/WFPC2 and Digitized Sky Survey images. In addition to a previously known outer dust ring (~30'' in diameter), the HST/WFPC2 scattered light image reveals an inner dust ring for the first time. This ring has a maximum radius of 6.5'' and is possibly related to a molecular envelope. Large-scale optical images show that V1331 Cyg is located at the tip of a long dust filament linking it to the dark cloud LDN 981. We discuss the origin of the observed dust morphology and analyze the object's relation to its parent dark cloud LDN 981. Finally, based on recent results from the literature, we investigate the properties of V1331 Cyg and conclude that in its current state the object does not show suffcient evidence to be characterized as an FU Ori object.Comment: 15 pages ApJ preprint style including 3 figures, accepted for publication in ApJ (Feb. 2007

The secondary minimum in YY Her: Evidence for a tidally distorted giant

We present and analyze quiescent UBVRI light curves of the classical symbiotic binary YY Her. We show that the secondary minimum, which is clearly visible only in the quiescent VRI light curves, is due to ellipsoidal variability of the red giant component. Our simple light curve analysis, by fitting of the Fourier cosine series, resulted in a self-consistent phenomenological model of YY Her, in which the periodic changes can be described by a combination of the ellipsoidal changes and a sinusoidal changes of the nebular continuum and line emission.Comment: 5 pages, 2 figures, to appear in Astronomy & Astrophysic

Flickering in FU Orionis

We analyze new and published optical photometric data of FU Orionis, an eruptive pre-main sequence star. The outburst consists of a 5.5 mag rise at B with an e-folding timescale of roughly 50 days. The rates of decline at B and V are identical, 0.015 +- 0.001 mag per yr. Random fluctuations superimposed on this decline have an amplitude of 0.035 +- 0.005 mag at V and occur on timescales of 1 day or less. Correlations between V and the color indices U-B, B-V, and V-R indicate that the variable source has the optical colors of a G0 supergiant. We associate this behavior with small amplitude flickering of the inner accretion disk.Comment: 19 pages of text, 3 tables, and 6 figures to be published in the Astrophysical Journal, 10 March 200

Observations of the 6 Centimeter Lines of OH in Evolved (OH/IR) Stars

Recent observational and theoretical advances have called into question traditional OH maser pumping models in evolved (OH/IR) stars. The detection of excited-state OH lines would provide additional constraints to discriminate amongst these theoretical models. In this Letter, we report on VLA observations of the 4750 MHz and 4765 MHz lines of OH toward 45 sources, mostly evolved stars. We detect 4765 MHz emission in the star forming regions Mon R2 and LDN 1084, but we do not detect excited-state emission in any evolved stars. The flux density and velocity of the 4765 MHz detection in Mon R2 suggests that a new flaring event has begun.Comment: 4 pages, to appear in ApJ

ВОЗМОЖНОСТИ СТРУЙНОЙ ИСКУССТВЕННОЙ ВЕНТИЛЯЦИИ ЛЕГКИХ ПРИ МИКРОХИРУРГИЧЕСКОМ ЭНДОЛАРИНГЕАЛЬНОМ ОПЕРАТИВНОМ ЛЕЧЕНИИ СТЕНОЗОВ ГОРТАНИ И ВЕРХНИХ ОТДЕЛОВ ТРАХЕИ БЕЗ НАЛОЖЕНИЯ ТРАХЕОСТОМЫ

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Влияние способа поддержания проходимости дыхательных путей при эндоскопических риносинусохирургических вмешательствах на кровоточивость в области операционного поля

The objective: to conduct a comparative assessment of the severity of intraoperative bleeding with different methods of airway management (using a laryngeal mask and endotracheal tube) during endoscopic rhinosinussurgical procedures.Subjects and Methods. A prospective randomized cohort single-center study of 160 cases of endoscopic rhinosinussurgical procedures under general anesthesia was conducted.Tracheal intubation (TI) was used in 79 cases (Group 1), a laryngeal mask (LM) – in 81 (Group 2). The evaluation criteria in the groups included the bleeding intensity (BI) by 6-point scale of average categories (Fromme-Boezaart Score), indicators characterizing the state of blood circulation during surgery: HR, BPsys., BPdiast., MAP, and perfusion index.Results. Significantly lower BI values were observed in Group 2 at all time points of the study (at the 10th, 30th and 60th minute of surgery). This was due both to using a laryngeal mask, and to lower HR, BPsys., BPdiast, and MAP.Conclusion. The use of a laryngeal mask for airway management during general anesthesia in endoscopic rhinosinussurgical procedures helps to reduce the intensity of surgical field bleeding.Управление степенью интраоперационного кровотечения играет ведущую роль в улучшении видимости операционного поля и снижении риска осложнений при эндоскопических риносинусохирургических (ЭРСХ) вмешательствах.Цель: провести сравнительную оценку выраженности интраоперационного кровотечения при разных способах поддержания проходимости дыхательных путей (с помощью ларингеальной маски и эндотрахеальной трубки) во время ЭРСХ-вмешательств.Материалы и методы. Проспективное рандомизированное когортное одноцентровое исследование 160 случаев ЭРСХ-вмешательств в условиях общей анестезии. Интубация трахеи (ИТ) использована в 79 случаях (1-я группа), ларингеальная маска (ЛМ) – в 81 (2-я группа). Критерии оценки в группах включали интенсивность кровотечения по 6-балльной шкале средних категорий (Fromme ‒ Boezaart Score) и показатели, характеризующие состояние кровообращения в ходе оперативного вмешательства (ЧСС, АДсист, АДдиаст, САД, перфузионный индекс).Результаты. Значимо меньшие показатели интенсивности кровотечения во всех точках исследования (на 10, 30 и 60-й мин операции) наблюдали во 2-й группе. Это было связано как с самим фактом использования ларингеальной маски, так и с более низкими значениями показателей ЧСС, АДсист, АДдиаст и САД.Вывод. Использование ларингеальной маски для поддержания проходимости дыхательных путей во время общей анестезии при ЭРСХ-вмешательствах способствует уменьшению локальной кровоточивости

Near infrared and the inner regions of protoplanetary disks

We examine the ``puffed-up inner disk'' model (Dullemond, Dominik & Natta 2001), proposed for explaining the near-IR excess radiation from Herbig Ae/Be stars. Detailed model computations show that the observed near-IR excess requires more hot dust than is contained in the puffed-up disk rim. The rim can produce the observed near-IR excess only if its dust has perfectly gray opacity, but such dust is in conflict with the observed 10$\mu$m spectral feature. We find that a compact ($\sim$ 10 AU) tenuous (\tau_V \la 0.4) dusty halo around the disk inner regions contains enough dust to readily explain the observations. Furthermore, this model also resolves the puzzling relationship noted by Monnier and Millan-Gabet (2002) between luminosity and the interferometric inner radii of disks.Comment: 14 pages, 10 figures, accepted in Ap