A 2.3-Day Periodic Variability in the Apparently Single Wolf-Rayet Star WR 134: Collapsed Companion or Rotational Modulation?

We present the results of an intensive campaign of spectroscopic and photometric monitoring of the peculiar Wolf-Rayet star WR 134 from 1989 to 1997. This unprecedentedly large data set allows us to confirm unambiguously the existence of a coherent 2.25 +/- 0.05 day periodicity in the line-profile changes of He II 4686, although the global pattern of variability is different from one epoch to another. This period is only marginally detected in the photometric data set. Assuming the 2.25 day periodic variability to be induced by orbital motion of a collapsed companion, we develop a simple model aiming at investigating (i) the effect of this strongly ionizing, accreting companion on the Wolf-Rayet wind structure, and (ii) the expected emergent X-ray luminosity. We argue that the predicted and observed X-ray fluxes can only be matched if the accretion on the collapsed star is significantly inhibited. Additionally, we performed simulations of line-profile variations caused by the orbital revolution of a localized, strongly ionized wind cavity surrounding the X-ray source. A reasonable fit is achieved between the observed and modeled phase-dependent line profiles of He II 4686. However, the derived size of the photoionized zone substantially exceeds our expectations, given the observed low-level X-ray flux. Alternatively, we explore rotational modulation of a persistent, largely anisotropic outflow as the origin of the observed cyclical variability. Although qualitative, this hypothesis leads to greater consistency with the observations.Comment: 34 pages, 16 figures. Accepted by the Astrophysical Journa

Optical Spectroscopy of X-Mega targets in Carina Nebula : III. The multiple system Tr 16-104 (≡CPD -59° 2603)

We discuss the orbital elements of the multiple system Tr 16-104 which is usually believed to be a member of the open cluster Trumpler 16 in the Carina complex. We show that Tr 16-104 could be a hierarchical triple system consisting of a short-period (2.15 d) eclipsing O7 V+O9.5 V binary bound to a B0.2 IV star. Our preliminary orbital solution of the third body indicates that the B star most probably describes an eccentric orbit with a period of ∼285 or ∼1341 d around the close binary. Folding photometric data from the literature with our new ephemerides, we find that the light curve of the close binary exhibits rather narrow eclipses indicating that the two O stars must be well inside their Roche lobes. Our analysis of the photometric data yields a lower limit on the inclination of the orbit of the close binary of i≥77°. The stellar radii and luminosities of the O7 V and O9.5 V stars are significantly smaller than expected for stars of this spectral type. Our results suggest that Tr 16-104 lies at a distance of the order of 2.5 kpc and support a fainter absolute magnitude for zero-age main-sequence O stars than usually adopted. We find that the dynamical configuration of Tr 16-104 corresponds to a hierarchical system that should remain stable provided that it suffers no strong perturbation. Finally, we also report long-term temporal variations of high-velocity interstellar Ca ii absorptions in the line of sight towards Tr 16-104.Facultad de Ciencias Astronómicas y Geofísica

A phase-resolved XMM-Newton Campaign on the Colliding Wind Binary HD 152248

We report the first results of an XMM-Newton monitoring campaign of the NGC 6231 open cluster in the Sco OB1 association. This first paper focuses on the massive colliding wind binary HD 152248, which is the brightest X-ray source of the cluster. The campaign, with a total duration of 180 ksec, was split into six separate observations, following the orbital motion of HD 152248. The X-ray flux from this system presents a clear, asymmetric modulation with the phase and ranges from 0.73 to 1.18 10-12 erg s-1 cm-2 in the [0.5-10.0 keV] energy band. The maximum of the emission is reached slightly after apastron. The EPIC spectra are quite soft and peak around 0.8-0.9 keV. We characterize their shape using several combinations of mekal models and power-law spectra and we detect significant spectral variability in the [0.5-2.5 keV] energy band. We also perform 2-D hydrodynamical simulations using different sets of parameters that closely reproduce the physical and orbital configuration of the HD 152248 system at the time of the six XMM-Newton pointings. This allows a direct confrontation of the model predictions with the constraints deduced from the X-ray observations of the system. We show that the observed variation of the flux can be explained by a variation of the X-ray emission from the colliding wind zone, diluted by the softer X-ray contribution of the two O-type stars of the system. Our simulations also reveal that the interaction region of HD 152248 should be highly unstable, giving rise to shells of dense gas that are separated by low density regions. Finally, we perform a search for short-term variability in the light curves of the system and we show that trends are present within several of the 30 ksec exposures of our campaign. Further, most of these trends are in good .Comment: Accepted by MNRAS; 22 pages; without figures; complete PS version (including figures) on http://vela.astro.ulg.ac.be/Preprints/index.htm

Accretion vs colliding wind models for the gamma-ray binary LS I +61 303: an assessment

LS I +61 303 is a puzzling Be/X-ray binary with variable gamma-ray emission at up TeV energies. The nature of the compact object and the origin of the high-energy emission are unclear. One family of models invokes particle acceleration in shocks from the collision between the B-star wind and a relativistic pulsar wind, while another centers on a relativistic jet powered by accretion. Recent high-resolution radio observations showing a putative "cometary tail" pointing away from the Be star near periastron have been cited as support for the pulsar-wind model. We wish here to carry out a quantitative assessment of these competing models for this extraordinary source. We apply a 3D SPH code for dynamical simulations of both the pulsar-wind-interaction and accretion-jet models. The former yields a description of the shape of the wind-wind interaction surface. The latter provides an estimation of the accretion rate. The results allow critical evaluation of how the two distinct models confront the data in various wavebands under a range of conditions. When one accounts for the 3D dynamical wind interaction under realistic constraints for the relative strength of the B-star and pulsar winds, the resulting form of the interaction front does not match the putative "cometary tail" claimed from radio observations. On the other hand, dynamical simulations of the accretion-jet model indicate that the orbital phase variation of accretion power includes a secondary broad peak well away from periastron, thus providing a plausible way to explain the observed TeV gamma ray emission toward apastron. We conclude that the colliding-wind model is not clearly established for LS I +61 303, while the accretion-jet model can reproduce many key characteristics of the observed TeV gamma-ray emission.Comment: Accepted for publication in A&A. The resolution of the figures is lower than in the journal paper to minimize file sizes. Seven pages, 5 figure

Spiralling out of control: 3D hydrodynamical modelling of the colliding winds in η \eta\thinspaceCarinae

Three dimensional (3D) adaptive-mesh refinement (AMR) hydrodynamical simulations of the wind-wind collision between the enigmatic super-massive star \etacar and its mysterious companion star are presented which include radiative driving of the stellar winds, gravity, optically-thin radiative cooling, and orbital motion. Simulations with static stars with a periastron passage separation reveal that the preshock companion star's wind speed is sufficiently reduced that radiative cooling in the postshock gas becomes important, permitting the runaway growth of non-linear thin shell (NTSI) instabilities which massively distort the WCR. However, large-scale simulations which include the orbital motion of the stars, show that orbital motion reduces the impact of radiative inhibition, and thus increases the acquired preshock velocities. As such, the postshock gas temperature and cooling time see a commensurate increase, and sufficient gas pressure is preserved to stabilize the WCR against catastrophic instability growth. We then compute synthetic X-ray spectra and lightcurves and find that, compared to previous models, the X-ray spectra agree much better with {\it XMM-Newton} observations just prior to periastron. The narrow width of the 2009 X-ray minimum can also be reproduced. However, the models fail to reproduce the extended X-ray mimimum from previous cycles. We conclude that the key to explaining the extended X-ray minimum is the rate of cooling of the companion star's postshock wind. If cooling is rapid then powerful NTSIs will heavily disrupt the WCR. Radiative inhibition of the companion star's preshock wind, albeit with a stronger radiation-wind coupling than explored in this work, could be an effective trigger.Comment: 25 pages, 20 figures, accepted for publication in Ap

Chandra X-ray spectroscopy of the very early O supergiant HD 93129A: constraints on wind shocks and the mass-loss rate

We present analysis of both the resolved X-ray emission line profiles and the broadband X-ray spectrum of the O2 If* star HD 93129A, measured with the Chandra HETGS. This star is among the earliest and most massive stars in the Galaxy, and provides a test of the embedded wind shock scenario in a very dense and powerful wind. A major new result is that continuum absorption by the dense wind is the primary cause of the hardness of the observed X-ray spectrum, while intrinsically hard emission from colliding wind shocks contributes less than 10% of the X-ray flux. We find results consistent with the predictions of numerical simulations of the line-driving instability, including line broadening indicating an onset radius of X-ray emission of several tenths Rstar. Helium-like forbidden-to-intercombination line ratios are consistent with this onset radius, and inconsistent with being formed in a wind-collision interface with the star's closest visual companion at a distance of ~100 AU. The broadband X-ray spectrum is fit with a dominant emission temperature of just kT = 0.6 keV along with significant wind absorption. The broadband wind absorption and the line profiles provide two independent measurements of the wind mass-loss rate: Mdot = 5.2_{-1.5}^{+1.8} \times 10^{-6} Msun/yr and Mdot = 6.8_{-2.2}^{+2.8} \times 10^{-6} Msun/yr, respectively. This is the first consistent modeling of the X-ray line profile shapes and broadband X-ray spectral energy distribution in a massive star, and represents a reduction of a factor of 3 to 4 compared to the standard H-alpha mass-loss rate that assumes a smooth wind.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical Society. 12 pages, 10 figures (incl. 5 color

The efficiency akatinoi-memantin at treatment vascular and mixed (vascular process in the combination to Alzheimer's atrophy) dementia (24-week open clinical research)

For the purpose of efficiency and safety studying antidemented preparation akatinoi-m em antin at vascular and mixed (vascular-atrophic) dementia the moderate and heavy degree in opened clinical research results of therapy by this preparation during 12-week and 24-week courses at 20 sick (9 - 45 % - patients with moderate degree dementia and 1 1 - 5 5 % of patients with heavy) were studied; with ’pure' vascular dementia was 14, and with combined - 6 patients. Except a cliniko-psychopathological method of research inspection of patients was spent by means of scales Hachinski, CGI - 1, MMSE (cognitive sphere), IADL, and also the quantity of time demanded for leaving and supervision of sick relatives was considered. It was in parallel studied by these methods 10 sick (5 patients with moderate degree of dementia and 5 with heavy degree - from these patients 2 with combined dem entia), receiving ‘usual" therapy without akatinoi-m em antin. The antidementia effect akatinoi-m em antin arises in 12 weeks of therapy: considerable positive dynamics is noted at 66,6 % of patients with moderate degree of weak-mindedness and at 54,5 % of patients with heavy degree. Treatment continuation akatinoi-memantin is necessary for maintenance and to a lesser degree improvement of the reached result. Good shipping of a preparation during all course (24 weeks) therapies is ascertained.С целью изучения эффективности и безопасности антидементного препарата акатинол-мемантина при сосудистых и смешанных (сосудисто-атрофических) деменциях умеренной и тяжёлой степени в открытом клиническом исследовании изучались результаты терапии этим препаратом в течение 12-недельного и 24-недельного курсов у 20 больных (9 - 45% - больных с умеренной степенью деменции и 11 - 55% больных с тяжёлой); с «чистой» сосудистой деменцией было 14, а с сочетанной - б больных. Кроме клинико-психопатологического метода исследования обследование больных проводилось с помощью шкал Hachinski, CGI - 1, MMSE (когнитивная сф ера), IADL, а также учитывалось количество времени, требуемого для ухода и надзора за больными близкими. Параллельно изучались этими методами 10 больных (5 больных с умеренной степенью слабоумия и 5 с тяжёлой - из этих больных 2 с сочетанной деменцией), получавших «обычную» терапию без акатинол-мемантина. Антидементный эффект акатинол-мемантина возникает уже через 12 недель терапии: значительная положительная динамика отмечена у 66,6% больных с умеренной степенью слабоумия и у 54,5% больных с тяжёлой степенью. Продолжение лечения акатинол-мемантином необходимо для поддержания и в меньшей степени улучшения достигнутого результата. Констатирована хорошая переносимость препарата в течение всего курса (24 недели) терапии

Investigating the X-ray emission from the massive WR+O binary WR 22 using 3D hydrodynamical models

We examine the dependence of the wind-wind collision and subsequent X-ray emission from the massive WR+O star binary WR~22 on the acceleration of the stellar winds, radiative cooling, and orbital motion. Simulations were performed with instantaneously accelerated and radiatively driven stellar winds. Radiative transfer calculations were performed on the simulation output to generate synthetic X-ray data, which are used to conduct a detailed comparison against observations. When instantaneously accelerated stellar winds are adopted in the simulation, a stable wind-wind collision region (WCR) is established at all orbital phases. In contrast, when the stellar winds are radiatively driven, and thus the acceleration regions of the winds are accounted for, the WCR is far more unstable. As the stars approach periastron, the ram pressure of the WR's wind overwhelms the O star's and, following a significant disruption of the shocks by non-linear thin-shell instabilities (NTSIs), the WCR collapses onto the O star. X-ray calculations reveal that when a stable WCR exists the models over-predict the observed X-ray flux by more than two orders of magnitude. The collapse of the WCR onto the O star substantially reduces the discrepancy in the $2-10\;$keV flux to a factor of $\simeq 6$ at $\phi=0.994$. However, the observed spectrum is not well matched by the models. We conclude that the agreement between the models and observations could be improved by increasing the ratio of the mass-loss rates in favour of the WR star to the extent that a normal wind ram pressure balance does not occur at any orbital phase, potentially leading to a sustained collapse of the WCR onto the O star. Radiative braking may then play a significant r\^{o}le for the WCR dynamics and resulting X-ray emission.Comment: 16 pages, 11 figures, 2 tables. Accepted for publication in A&

Electron Cooling Experiments in CSR

The six species heavy ion beam was accumulated with the help of electron cooling in the main ring of Cooler Storage Ring of Heavy Ion Research Facility in Lanzhou(HIRFL-CSR), the ion beam accumulation dependence on the parameters of cooler was investigated experimentally. The 400MeV/u 12C6+ and 200MeV/u 129Xe54+ was stored and cooled in the experimental ring CSRe, the cooling force was measured in different condition.Comment: 5 pages 11 figure

Optical Spectroscopy of X-Mega targets in Carina Nebula : III. The multiple system Tr 16-104 (≡CPD -59° 2603)

We discuss the orbital elements of the multiple system Tr 16-104 which is usually believed to be a member of the open cluster Trumpler 16 in the Carina complex. We show that Tr 16-104 could be a hierarchical triple system consisting of a short-period (2.15 d) eclipsing O7 V+O9.5 V binary bound to a B0.2 IV star. Our preliminary orbital solution of the third body indicates that the B star most probably describes an eccentric orbit with a period of ∼285 or ∼1341 d around the close binary. Folding photometric data from the literature with our new ephemerides, we find that the light curve of the close binary exhibits rather narrow eclipses indicating that the two O stars must be well inside their Roche lobes. Our analysis of the photometric data yields a lower limit on the inclination of the orbit of the close binary of i≥77°. The stellar radii and luminosities of the O7 V and O9.5 V stars are significantly smaller than expected for stars of this spectral type. Our results suggest that Tr 16-104 lies at a distance of the order of 2.5 kpc and support a fainter absolute magnitude for zero-age main-sequence O stars than usually adopted. We find that the dynamical configuration of Tr 16-104 corresponds to a hierarchical system that should remain stable provided that it suffers no strong perturbation. Finally, we also report long-term temporal variations of high-velocity interstellar Ca ii absorptions in the line of sight towards Tr 16-104.Facultad de Ciencias Astronómicas y Geofísica