bluuebunny/crossref_metadata_2025_split huggingface dataset:
Imaging “Pinwheel” nebulae with optical long-baseline interferometry
Authors: Millour Florentin , Driebe Thomas , Groh Jose H. , Chesneau Olivier , Weigelt Gerd , Liermann Adriane , Meilland Anthony 
Published: July 2011

AbstractDusty Wolf-Rayet stars are few but remarkable in terms of dust production rates (up to Ṁ = 10−6 M⊙/yr). Infrared excesses associated to mass-loss are found in the sub-types WC8 and WC9. Few WC9d stars are hosting a “pinwheel” nebula, indirect evidence of a companion star around the primary. While few other WC9d stars have a dust shell which has been barely resolved so far, the available angular resolution offered by single telescopes is insufficient to confirm if they also host “pinwheel” nebulae or not. In this article, we present the possible detection of such nebula around the star WR 118. We discuss about the potential of interferometry to image more “pinwheel” nebulae around other WC9d stars.
Images of unclassified and supergiant B[e] stars disks with interferometry
Authors: Millour Florentin , Meilland Anthony , Chesneau Olivier , Fernandes Marcelo Borges , Groh Jose H. , Driebe Thomas , Liermann Adrianne , Weigelt Gerd 
Published: July 2011

AbstractB[e] stars are among the most peculiar objects in the sky. This spectral type, characterised by allowed and forbidden emission lines, and a large infrared excess, does not represent an homogenous class of objects, but instead, a mix of stellar bodies seen in all evolutionary status. Among them, one can find Herbig stars, planetary nebulae central stars, interacting binaries, supermassive stars, and even “unclassified” B[e] stars: systems sharing properties of several of the above. Interferometry, by resolving the innermost regions of these stellar systems, enables us to reveal the true nature of these peculiar stars among the peculiar B[e] stars.
Properties of the circumstellar dust in galactic FS CMa objects
Authors: Miroshnichenko Anatoly S. , Gray Richard O. , Bjorkman Karen S. , Rudy Richard J. , Lynch David K. , Carciofi Alex C. 
Published: July 2011

AbstractFS CMa objects are a group of hot stars that exhibit the B[e] phenomenon. The group was defined a few years ago on the basis of the formerly known unclassified B[e] stars and newly discovered objects. One of their main features is the presence of hot circumstellar dust whose properties were unknown. We present IR spectra of nearly 20 FS CMa objects obtained with the Spitzer Space Telescope. Dusty features, such as broad silicate bands in emission and narrow bands that are usually explained by PAHs, are detected. The IR fluxes are compared to those detected by IRAS and MSX. Main results of the data analysis are briefly discussed.
Effect of Be-disk evolution on the global one-armed oscillations
Authors: Oktariani Finny , Okazaki Atsuo T. 
Published: July 2011

AbstractWe consider the effect of density distribution evolution on the global one-armed oscillation modes in disks around Be stars. Previous studies of global oscillations in Be disks assumed a power-law density distribution of the disk. However, observational results show that some Be stars exhibit evidence of formation and dissipation of the equatorial disk. This causes the disk density distribution can be far from a power-law form. Performing calculations for several times in the disk formation and dissipation stages, we find one-armed modes confined to the inner part of the disk in both stages. In the disk formation stage, the oscillation frequency stays approximately constant after the disk is fully developed. In the dissipation stage of the Be disk, the local precession frequency is, in general, higher than in the disk formation stage. Thus, we expect that V/R periods become shorter as the innermost part of the disk starts to accrete.
Pulsations in Wolf-Rayet stars: observations with MOST
Authors: Chené André-Nicolas , Moffat Anthony F. J. 
Published: July 2011

AbstractPhotometry of Wolf-Rayet (WR) stars obtained with the first Canadian space telescope MOST (Microvariability and Oscillations of STars) has revealed multimode oscillations mainly in continuum light that suggest stellar pulsations could be a significant contributing factor to the mass-loss rates. Since the first clear detection of a pulsation period of P = 9.8h in WR123, two other stars have also shown periods of a few days, which must be related to stellar pulsations.
Seismic modelling of OB stars
Authors: Dupret Marc-Antoine , Godart Mélanie , Belkacem Kevin , Noels Arlette 
Published: July 2011

AbstractA review of the ability of asteroseismology to probe the internal physics of OB stars is presented. The main constraints that can be obtained from the frequency spectrum in p- and g-modes pulsators are discussed. Next, we consider energetic aspects of the pulsations in OB stars and show how such study also allows to constrain their internal physics. The cases of p-mixed modes (β Cep stars), g-modes (SPB stars), strange modes and stochastically excited modes are considered.
Radial and nonradial oscillations of massive supergiants
Authors: Saio Hideyuki 
Published: July 2011

AbstractStability of radial and nonradial oscillations of massive supergiants is discussed. The kappa-mechanism and strange-mode instability excite oscillations having various periods in wide ranges of the upper part of the HR diagram. In addition, in very luminous (logL/L⊙≳ 5.9) models, monotonously unstable modes exist, which probably indicates the occurrence of optically thick winds. The instability boundary is not far from the Humphreys-Davidson limit. Furthermore, it is found that there exist low-degree (ℓ = 1, 2) oscillatory convection modes associated with the Fe-opacity peak convection zone, and they can emerge to the stellar surface so that they are very likely observable in a considerable range in the HR diagram. The convection modes have periods similar to g-modes, and their growth-times are comparable to the periods. Theoretical predictions are compared with some of the supergiant variables.
Very massive binaries in R 136
Authors: Chené André-Nicolas , Schnurr Olivier , Crowther Paul A. , Lajus Eduardo F. , Moffat Anthony F. J. 
Published: July 2011

AbstractAs recent observations have shown, luminous, hydrogen-rich WN5-7h stars (and their somewhat less extreme cousins, O3f/WN6 stars) are the most massive main-sequence stars known. However, not nearly enough very massive stars have been reliably weighed to yield a clear picture of the upper initial-mass function (IMF). We therefore have carried out repeated high-quality spectroscopy of four new O3f/WN6 and WN5-7h binaries in R136 in the LMC with GMOS at Gemini-South, to derive Keplerian orbits for both components, respectively, and thus to directly determine their masses. We also monitored binary candidates and other, previously unsurveyed stars, to increase the number of very massive stars that can be directly weighed.
Using the orbiting companion to trace WR wind structures in the 29d WC8d + O8-9IV binary CV Ser
Authors: David-Uraz Alexandre , Moffat Anthony F. J. 
Published: July 2011

AbstractWe have used continuous, high-precision, broadband visible photometry from the MOST satellite to trace wind structures in the WR component of CV Ser over more than a full orbit. Most of the small-scale light-curve variations are likely due to extinction by clumps along the line of sight to the O companion as it orbits and shines through varying columns of the WR wind. Parallel optical spectroscopy from the Mont Megantic Observatory is used to refine the orbital and wind-collision parameters, as well as to reveal line emission from clumps.
Spectroscopic follow-up of the colliding-wind binary WR 140 during the 2009 January periastron passage
Authors: Fahed Rémi , Moffat Anthony F. J. , Zorec Juan , Eversberg Thomas , Chené André-Nicolas , Alves Filipe , Arnold Wolfgang , Bergmann Thomas , Carreira Luis F. Gouveia , Dias Filipe Marques , Fernando Alberto , Gallego José Sánchez , Hunger Thomas , Knapen Johan H. , Leadbeater Robin , Morel Thierry , Rauw Grégor , Reinecke Norbert , Ribeiro José , Romeo Nando , dos Santos Eva M. , Schanne Lothar , Stahl Otmar , Stober Barbara , Stober Berthold , Viegas Nelson G. Correia , Vollmann Klaus , Corcoran Michael F. , Dougherty Sean M. , Pittard Julian M. , Pollock Andy M. T. , Williams Peredur M. 
Published: July 2011

AbstractWe present the results from the spectroscopic follow-up of WR140 (WC7 + O4-5) during its last periastron passage in january 2009. This object is known as the archetype of colliding wind binaries and has a relatively large period (≃8 years) and eccentricity (≃0.89). We provide updated values for the orbital parameters, new estimates for the WR and O star masses and new constraints on the mass-loss rates.
The WR/LBV system HD 5980: wind-velocity – brightness correlations
Authors: Koenigsberger Gloria , Georgiev Leonid , Hillier D. John , Morrell Nidia , Barbá Rodolfo , Gamen Roberto 
Published: July 2011

AbstractThe massive eclipsing system HD 5980 in the Small Magellanic Cloud presented sudden ~1–3 mag eruptive events in 1993-1994, the nature of which is still unexplained. We recently showed that these brief eruptions occurred at the beginning of an extended high state of activity which is characterized by large emission-line intensities and that this high state is currently ending (Koenigsberger et al. 2010). Star A, the more massive member of the 19-day binary, is responsible for the spectacular spectral variations observed over the past 3 decades (see Figure 1). It has a He-enriched stellar wind and is over-luminous for its mass, implying an advanced evolutionary state (Koenigsberger et al. 1998). Data obtained over the past 3 decades show that Star A's wind speed slowed down as the system brightened. Also present in these data is a correlated increase in emission-line strength, visual and UV brigthness. The latter suggests that the high activity state in HD 5980 may be attributed to a bolometric luminosity increase, consistent with the results of Drissen et al. (2001). Hence, HD 5980 may be providing the important clues needed for understanding the behavior of other luminous blue variables and for understainding the evolutionary transition between massive O-type stars and Wolf-Rayet stars.
HD 150136: towards one of the most massive systems?
Authors: Mahy Laurent , Gosset Eric , Sana Hugues , Rauw Gregor , Fauchez Thomas , Nitschelm Christian 
Published: July 2011

AbstractWe present the preliminary results of an intensive monitoring devoted to HD 150136. Already quoted as an O3+O6 binary, we detected a third O-type component physically linked to the system, making it one of the nearest (1.3 kpc) most massive systems known until now (~134M⊙). To determine the physical parameters of this system, we applied a disentangling program to study individually the three components. It allows us to constrain their spectral types and to derive a new orbital solution for the short-period system.
Masses of the astrometric SB2 ζ Ori A
Authors: Rivinius Thomas , Hummel Christian A. , Stahl Otmar 
Published: July 2011

AbstractWe report the first dynamic mass for an O-type supergiant, the interferometrically resolved SB2 system ζ Ori A (O9.5Ib+B0/1). The separation of the system excludes any previous mass-transfer, ensuring that the derived masses can be compared to single star evolutionary tracks.
OB-stars as extreme condition test beds
Authors: Puls Joachim , Sundqvist Jon O. , Rivero González Jorge G. 
Published: July 2011

AbstractMassive stars are inherently extreme objects, in terms of radiation, mass loss, rotation, and sometimes also magnetic fields. Concentrating on a (personally biased) subset of processes related to pulsations, rapid rotation and its interplay with mass-loss, and the bi-stability mechanism, we will discuss how active (and normal) OB stars can serve as appropriate laboratories to provide further clues.
Investigation of X-ray transient CI Cam as an unique star with the B[e]phenomenon
Authors: Barsukova Elena A. , Burenkov Alexandr N. , Klochkova Valentina G. , Goranskij Vitalij P. , Metlova Nataly V. , Kroll Peter , Miroshnichenko Anatoly S. 
Published: July 2011

AbstractDouble mode pulsations of the B4 component in the system of CI Cam were detected. The photometric 19.4 day orbital period of CI Cam was confirmed with the plates of the Sonneberg collection for a long period of time before the unique 1998 outburst. The amplitude of the periodic component of 0.08 mag before the outburst was larger than that of 0.03 mag after the outburst.
X-ray emission from hydrodynamical wind simulations in non-LTE models
Authors: Krtička Jiri , Feldmeier Achim , Oskinova Lidia M. , Kubát Jiri , Hamann Wolf-Rainer 
Published: July 2011

AbstractMassive hot stars are strong sources of X-ray emission originating in their winds. Although hydrodynamical wind simulations that are able to predict this X-ray emission are available, the inclusion of X-rays in stationary wind models is usually based on crude approximations. To improve this, we use results from time-dependent hydrodynamical simulations of the line-driven wind instability to derive an analytical approximation of X-ray emission in the stellar wind. We use this approximation in our non-LTE wind models and find that an improved inclusion of X-rays leads to a better agreement between model ionization fractions and those derived from observations. Furthermore, the slope of the Lx-L relation is in better agreement with observations, albeit the X-ray luminosity is underestimated by a factor of three. We propose that a possible solution for this discrepancy is connected with the wind porosity.
X-Ray modeling of η Carinae & WR 140 from SPH simulations
Authors: Russell Christopher M. P. , Corcoran Michael F. , Okazaki Atsuo T. , Madura Thomas I. , Owocki Stanley P. 
Published: July 2011

AbstractThe colliding wind binary (CWB) systems η Carinae and WR140 provide unique laboratories for X-ray astrophysics. Their wind-wind collisions produce hard X-rays that have been monitored extensively by several X-ray telescopes, including RXTE. To interpret these RXTE X-ray light curves, we apply 3D hydrodynamic simulations of the wind-wind collision using smoothed particle hydrodynamics (SPH). We find adiabatic simulations that account for the absorption of X-rays from an assumed point source of X-ray emission at the apex of the wind-collision shock cone can closely match the RXTE light curves of both η Car and WR140. This point-source model can also explain the early recovery of η Car's X-ray light curve from the 2009.0 minimum by a factor of 2-4 reduction in the mass loss rate of η Car. Our more recent models account for the extended emission and absorption along the full wind-wind interaction shock front. For WR140, the computed X-ray light curves again match the RXTE observations quite well. But for η Car, a hot, post-periastron bubble leads to an emission level that does not match the extended X-ray minimum observed by RXTE. Initial results from incorporating radiative cooling and radiative forces via an anti-gravity approach into the SPH code are also discussed.
Interferometric survey of Be stars with the CHARA array
Authors: Touhami Yamina N. , Gies Douglas R. , Schaefer Gail H. , Richardson Noel D. , Williams Stephen J. , Grundstrom Erika D. , McSwain M. Virginia 
Published: July 2011

AbstractWe present the first spatially resolved observations of circumstellar envelopes of 25 bright northern Be stars. The survey was performed with the CHARA Array interferometer in the K-band at intermediate and long baselines. The interferometric visibilities are well fitted by a viscous disk model where the gas density steeply decreases with the radius. Physical and geometrical parameters such as the density profile, the inclination, and the position angles of the circumstellar disks are determined. We find that the density radial exponent ranges between n ≈ 2.4 − 3.2, which is consistent with previous IRAS measurements. We have also obtained simultaneous optical and near-IR spectrophotometric measurements, and found that the model reproduces well the observed disk IR-continuum excess emission. By combining the projected rotational velocity of the Be star with the disk inclination derived from interferometry, we give estimates of the equatorial rotational velocities of these Be stars.
Non-thermal radio emission from colliding-wind binaries: modelling Cyg OB2 No. 8A and No. 9
Authors: Volpi Delia , Blomme Ronny , De Becker Michael , Rauw Gregor 
Published: July 2011

AbstractSome OB stars show variable non-thermal radio emission. The non-thermal emission is due to synchrotron radiation that is emitted by electrons accelerated to high energies. The electron acceleration occurs at strong shocks created by the collision of radiatively-driven stellar winds in binary systems. Here we present results of our modelling of two colliding wind systems: Cyg OB2 No. 8A and Cyg OB2 No. 9.
Virtual screening to design drug molecules for human proto oncogene Fyn kinase
Authors: Mannekumar Manne , Sravana lakshmi Pasupuleti , Vani Priyadarshini Ikkurthi , Pradhan Dibyabhaba , Umamaheswari Amineni 
Published: July 2011

AbstractHuman Fyn tyrosine kinase, a Src-family enzyme plays a pivotal role in the integrin mediated cell signaling pathway and is known to interact with several molecular signals including FAK and paxillin that accounts for morphogenic transformation leading to cancer. The present study was aimed to design a persuasive inhibitor for Fyn kinase. The crystal structure was optimized and energy minimized applying OPLS2001 force field in Maestro v9.0. The inhibitor binding site residues such as LEU-17, GLY-18, ASN-19, VAL-25, ALA-37, LYS-39, GLU-54, THR-82, GLU-83, TYR-84, MET-85, GLY-88, ALA-134, ASN-135, LEU-137, and ASP-148 were located from the Fyn kinase co-crystal structure with staurosporine. Three published inhibitors (staurosporine, Rosmarinic acid and dasatinib) of Fyn kinase were searched through high throughput virtual screening in Ligand.Info Metadatabase and generated 1163 structural analogues. Glide 5.5 docking was performed to predict the binding orientation of prepared ligand molecule into a grid of 20 x 20 x 20 Å created around the centroid of optimized Fyn kinase. Isomers and tautomers were generated for 1163 chemical entities through LigPrep. Ligands having reactive functional groups and poor ADME properties were rejected from the prepared dataset and docked into the predicted active site of human Fyn kinase through a systematic application of virtual screening using Glide v5.5. Five lead molecules with good XP GScores were obtained with their binding orientations, further XP Gscores were interrelated with the existing three published inhibitors. Lead1 (nor dihydroguaiaretic acid) was observed to have the lowest XP Gscore (-11.39 Kcal/mol) compared to three published inhibitors and blocked the Fyn kinase active site by forming hydrogen bonds and good Van der Waals contacts. Thus, nor dihydroguaiaretic acid would be useful as drug molecule if synthesized and tested in animal models.
Small artery function 2 years postpartum in women with altered glycaemic distributions in their preceding pregnancy
Authors: Banerjee Moulinath , Anderson Simon G. , Malik Rayaz A. , Austin Clare E. , Cruickshank J. Kennedy 
Published: July 2011

GDM (gestational diabetes mellitus) is associated with later adverse cardiovascular risk. The present study examined the relationship between glycaemia during pregnancy and small artery function and structures approx. 2 years postpartum. Women were originally enrolled in the HAPO (Hyperglycaemia and Adverse Pregnancy Outcome) study from which they were classified by their glycaemic distribution during pregnancy as controls (in the lower half of the distribution), UQ (upper quartile; in the UQ of the glycaemic distribution) or having had overt GDM. Subcutaneous arteries from a gluteal fat biopsy taken at follow-up 2 years later were examined using wire myography. Small artery structure, stiffness and vasoconstrictor responses were similar across groups. Maximal endothelium-dependent dilation in response to carbachol was impaired in arteries from both GDM (43.3%, n=8 and P=0.01) and UQ (51.7%, n=13 and P=0.04) women despite generally ‘normal’ current glycaemia (controls, 72.7% and n=8). Inhibition of NOS (nitric oxide synthase) significantly reduced maximum endothelium-dependent dilation in controls but had no effect on arteries from UQ and GDM women, suggesting impaired NOS activity in these groups. Endothelium-independent dilation was unaffected in arteries from previous GDM and UQ women when compared with the control group. Multiple regression analysis suggested that BMI (body mass index) at biopsy was the most potent factor independently associated with small artery function, with no effect of current glycaemia. Overweight women with either GDM or marginally raised glycaemia during pregnancy (our UQ group) had normal vascular structure and stiffness, but clearly detectable progressively impaired endothelium-dependent function at 2 years follow-up. These results suggest that vascular pathology, which may still be reversible, is detectable very early in women at risk of decline into Type 2 diabetes mellitus.
Identification of unique mechanisms for triterpene biosynthesis in
Botryococcus braunii
Authors: Niehaus Tom D. , Okada Shigeru , Devarenne Timothy P. , Watt David S. , Sviripa Vitaliy , Chappell Joe 
Published: July 2011

Botryococcene biosynthesis is thought to resemble that of squalene, a metabolite essential for sterol metabolism in all eukaryotes. Squalene arises from an initial condensation of two molecules of farnesyl diphosphate (FPP) to form presqualene diphosphate (PSPP), which then undergoes a reductive rearrangement to form squalene. In principle, botryococcene could arise from an alternative rearrangement of the presqualene intermediate. Because of these proposed similarities, we predicted that a botryococcene synthase would resemble squalene synthase and hence isolated squalene synthase-like genes from
Botryococcus braunii
race B. While
B. braunii
does harbor at least one typical squalene synthase, none of the other three squalene synthase-like (SSL) genes encodes for botryococcene biosynthesis directly. SSL-1 catalyzes the biosynthesis of PSPP and SSL-2 the biosynthesis of bisfarnesyl ether, while SSL-3 does not appear able to directly utilize FPP as a substrate. However, when combinations of the synthase-like enzymes were mixed together, in vivo and in vitro, robust botryococcene (SSL-1+SSL-3) or squalene biosynthesis (SSL1+SSL-2) was observed. These findings were unexpected because squalene synthase, an ancient and likely progenitor to the other
Botryococcus
triterpene synthases, catalyzes a two-step reaction within a single enzyme unit without intermediate release, yet in
B. braunii
, these activities appear to have separated and evolved interdependently for specialized triterpene oil production greater than 500 MYA. Coexpression of the SSL-1 and SSL-3 genes in different configurations, as independent genes, as gene fusions, or targeted to intracellular membranes, also demonstrate the potential for engineering even greater efficiencies of botryococcene biosynthesis.
Co-Constructing Community Forests in Nepal: Mutual Constraint in a Transnational Aid Network
Authors: Thoms Christopher A. 
Published: July 2011

Abstract
Community forests in Nepal are co-constructed by multiple actors working together in a way that is mutually constraining for those involved in the network. Each network actor has goals/intentions that are mediated at the network level until the network as a whole develops a common, relatively “weak” goal sometimes far removed from individual starting goals. This mutual constraint prevents significant breakthroughs in restructuring local-level wealth and power disparities, which in turn play a role in depressing the livelihoods of marginalized households in rural Nepal.