@inproceedings{PulsMarkovaNajarroetal.2007,
  author    = {Puls, Joachim and Markova, N. and Najarro, F. and Hanson, M. M.},
  title     = {Clumping in O-star winds},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17683},
  year      = {2007},
  abstract  = {We review various diagnostics of clumping in O-star winds, with special emphasis on its radial stratification. Implications and problems are discussed, and promising NIR methods are presented.},
  language  = {en}
}
@inproceedings{StLouisMoffat2007,
  author    = {St-Louis, N. and Moffat, Anthony F. J.},
  title     = {Do clumping corrections increase with decreasing mass-loss rates?},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17696},
  year      = {2007},
  abstract  = {We report on new mass-loss rate estimates for O stars in six massive binaries using the amplitude of orbital-phase dependent, linear-polarimetric variability caused by electron scattering off free electrons in the winds. Our estimated mass-loss rates for luminous O stars are independent of clumping. They suggest similar clumping corrections as for WR stars and do not support the recently proposed reduction in mass-loss rates of O stars by one or two orders of magnitude.},
  language  = {en}
}
@inproceedings{Smith2007,
  author    = {Smith, Nathan},
  title     = {Independent signs of lower mass-loss rates for O-type stars},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17659},
  year      = {2007},
  abstract  = {I discuss observational evidence - independent of the direct spectral diagnostics of stellar winds themselves - suggesting that mass-loss rates for O stars need to be revised downward by roughly a factor of three or more, in line with recent observed mass-loss rates for clumped winds. These independent constraints include the large observed mass-loss rates in LBV eruptions, the large masses of evolved massive stars like LBVs and WNH stars, WR stars in lower metallicity environments, observed rotation rates of massive stars at different metallicity, supernovae that seem to defy expectations of high mass-loss rates in stellar evolution, and other clues. I pay particular attention to the role of feedback that would result from higher mass-loss rates, driving the star to the Eddington limit too soon, and therefore making higher rates appear highly implausible. Some of these arguments by themselves may have more than one interpretation, but together they paint a consistent picture that steady line-driven winds of O-type stars have lower mass-loss rates and are significantly clumped.},
  language  = {en}
}
@inproceedings{VotrubaFeldmeierKubatetal.2007,
  author    = {Votruba, V. and Feldmeier, Achim and Kub{\´a}t, Jiř{\´i} and R{\"a}tzel, D.},
  title     = {Multicomponent stellar wind of hot stars},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17677},
  year      = {2007},
  abstract  = {We developed a time-dependent multicomponent hydrodynamical code for simulation of the stellar wind from hot stars and applied it to stars with high and low density winds.},
  language  = {en}
}
@inproceedings{Lobel2007,
  author    = {Lobel, A.},
  title     = {Modeling DACs in UV lines of massive hot stars},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17856},
  year      = {2007},
  abstract  = {We apply the 3-dimensional radiative transport codeWind3D to 3D hydrodynamic models of Corotating Interaction Regions to fit the detailed variability of Discrete Absorption Components observed in Si iv UV resonance lines of HD 64760 (B0.5 Ib). We discuss important effects of the hydrodynamic input parameters on these large-scale equatorial wind structures that determine the detailed morphology of the DACs computed with 3D transfer. The best fit model reveals that the CIR in HD 64760 is produced by a source at the base of the wind that lags behind the stellar surface rotation. The non-corotating coherent wind structure is an extended density wave produced by a local increase of only 0.6\% in the smooth symmetric wind mass-loss rate.},
  language  = {en}
}
@inproceedings{PrinjaHodgesMassaetal.2007,
  author    = {Prinja, R. K. and Hodges, S. E. and Massa, D. L. and Fullerton, A. W. and Burnley, A. W.},
  title     = {Structure in the fast wind of NGC6543},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17788},
  year      = {2007},
  abstract  = {We exploit time-series \$FUSE\$ spectroscopy to {\it uniquely} probe spatial structure and clumping in the fast wind of the central star of the H-rich planetary nebula NGC~6543 (HD~164963). Episodic and recurrent optical depth enhancements are discovered in the P{\sc v} absorption troughs, with some evidence for a \$\sim\$ 0.17-day modulation time-scale. The characteristics of these features are essentially identical to the discrete absorption components' (DACs) commonly seen in the UV lines of massive OB stars, suggesting the temporal structures seen in NGC~6543 likely have a physical origin that is similar to that operating in massive, luminous stars. The mechanism for forming coherent perturbations in the outflows is therefore apparently operating equally in the radiation-pressure-driven winds of widely differing momenta (\$\mdot\$\$v_\infty\$\$R_\star^{0.5}\$) and flow times, as represented by OB stars and CSPN.},
  language  = {en}
}
@inproceedings{Marchenko2007,
  author    = {Marchenko, S. V.},
  title     = {Wind inhomogeneities in low-Z environment : observations},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17769},
  year      = {2007},
  abstract  = {We discuss the results of time-resolved spectroscopy of three presumably single Population I Wolf-Rayet stars in the Small Magellanic Cloud, where the ambient metallicity is \$\sim 1/5 Z_\odot\$. We were able to detect and follow numerous small-scale wind-embedded inhomogeneities in all observed stars. The general properties of the moving features, such as their velocity dispersions, emissivities and average accelerations, closely match the corresponding characteristics of small-scale inhomogeneities in the winds of Galactic Wolf-Rayet stars.},
  language  = {en}
}
@inproceedings{NajarroPulsHerreroetal.2007,
  author    = {Najarro, F. and Puls, Joachim and Herrero, A. and Hanson, M. M. and Mart{\´i}n-Pintado, J. and Hillier, D. J.},
  title     = {Tracking the Clumping in OB Stars from UV to radio},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17701},
  year      = {2007},
  abstract  = {We review different line and continua diagnostics from the UV to radio, which can be utilized to simultaneously constrain the clumping structure throughout the stellar wind of massive OB stars.},
  language  = {en}
}
@inproceedings{Massa2007,
  author    = {Massa, D. L.},
  title     = {Discussion: Spectroscopy and Mass-Loss Diagnostics},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17821},
  year      = {2007},
  language  = {en}
}
@inproceedings{LiermannHamann2007,
  author    = {Liermann, A. and Hamann, Wolf-Rainer},
  title     = {Clumping in Galactic WN stars : a comparison of mass loss rates from UV/optical \& radio diagnostics},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17816},
  year      = {2007},
  abstract  = {The mass loss rates and other parameters for a large sample of Galactic WN stars have been revised by Hamann et al. (2006), using the most up-to date Potsdam Wolf-Rayet (PoWR) model atmospheres. For a sub-sample of these stars exist measurements of their radio free-free emission. After harmonizing the adopted distance and terminal wind velocities, we compare the mass loss rates obtained from the two diagnostics. The differences are discussed as a possible consequence of different clumping contrast in the line-forming and radio-emitting regions.},
  language  = {en}
}
@inproceedings{RaassenHuchtMilleretal.2007,
  author    = {Raassen, A. J. J. and Hucht, K. A. van der and Miller, N. A. and Cassinelli, Joseph P.},
  title     = {XMM-Newton observations of zeta Orionis (O9.7 Ib) : a collisional ionization equilibrium model},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17747},
  year      = {2007},
  abstract  = {We present the analysis of XMM-Newton observations of ζ Orionis. The analysis is based on fitting to the total spectrum as well as diagnostics of individual line.},
  language  = {en}
}
@inproceedings{IgnaceGayley2007,
  author    = {Ignace, R. and Gayley, K. G.},
  title     = {Circumstellar Magnetic Field Diagnostics from Line Polarization},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18066},
  year      = {2007},
  language  = {en}
}
@inproceedings{WalterZuritaHerasLeyder2007,
  author    = {Walter, R. and Zurita-Heras, J. and Leyder, J.-C.},
  title     = {Probing clumpy stellar winds with a neutron star},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18024},
  year      = {2007},
  abstract  = {INTEGRAL tripled the number of super-giant high-mass X-ray binaries (sgHMXB) known in the Galaxy by revealing absorbed and fast transient (SFXT) systems. Quantitative constraints on the wind clumping of massive stars can be obtained from the study of the hard X-ray variability of SFXT. A large fraction of the hard X-ray emission is emitted in the form of flares with a typical duration of 3 ksec, frequency of 7 days and luminosity of \$10^{36}\$ erg/s. Such flares are most probably emitted by the interaction of a compact object orbiting at \$\sim10~R_*\$ with wind clumps (\$10^{22 ... 23}\$ g) representing a large fraction of the stellar mass-loss rate. The density ratio between the clumps and the inter-clump medium is \$10^{2 ... 4}\$. The parameters of the clumps and of the inter-clump medium, derived from the SFXT flaring behavior, are in good agreement with macro-clumping scenario and line-driven instability simulations. SFXT are likely to have larger orbital radius than classical sgHMXB.},
  language  = {en}
}
@inproceedings{CassinelliIgnaceWaldronetal.2007,
  author    = {Cassinelli, Joseph P. and Ignace, R. and Waldron, W. and Cho, J. and Murphy, N. and Lazarian, A.},
  title     = {X-ray line emission produced in clump bow shocks},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18057},
  year      = {2007},
  abstract  = {We summarize Chandra observations of the emission line profiles from 17 OB stars. The lines tend to be broad and unshifted. The forbidden/intercombination line ratios arising from Helium-like ions provide radial distance information for the X-ray emission sources, while the H-like to He-like line ratios provide X-ray temperatures, and thus also source temperature versus radius distributions. OB stars usually show power law differential emission measure distributions versus temperature. In models of bow shocks, we find a power law differential emission measure, a wide range of ion stages, and the bow shock flow around the clumps provides transverse velocities comparable to HWHM values. We find that the bow shock results for the line profile properties, consistent with the observations of X-ray line emission for a broad range of OB star properties.},
  language  = {en}
}
@inproceedings{Runacres2007,
  author    = {Runacres, M. C.},
  title     = {Hydrodynamical models of clumping beyond 50 R∗},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18030},
  year      = {2007},
  abstract  = {We present one-dimensional, time-dependent models of the clumps generated by the linedeshadowing instability. In order to follow the clumps out to distances of more than 1000 R∗, we use an efficient moving-box technique. We show that, within the approximations, the wind can remain clumped well into the formation region of the radio continuum.},
  language  = {en}
}
@inproceedings{SchnerrHenrichs2007,
  author    = {Schnerr, R. S. and Henrichs, H. F.},
  title     = {Magnetic fields and wind variability in massive stars},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18075},
  year      = {2007},
  abstract  = {This paper describes the thesis work of Schnerr (2007) entitled "Magnetic fields and mass loss in massive stars", which aimed at a better understanding of the impact of magnetic fields on the winds of massive stars.},
  language  = {en}
}
@inproceedings{LeuteneggerCohenKahnetal.2007,
  author    = {Leutenegger, M. A. and Cohen, David H. and Kahn, S. M. and Owocki, S. P. and Paerels, F. B. S.},
  title     = {Resonance scattering in the X-ray emission lines profiles of ζ Puppis},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18085},
  year      = {2007},
  abstract  = {We present XMM-Newton Reflection Grating Spectrometer observations of pairs of X-ray emission line profiles from the O star ζ Pup that originate from the same He-like ion. The two profiles in each pair have different shapes and cannot both be consistently fit by models assuming the same wind parameters. We show that the differences in profile shape can be accounted for in a model including the effects of resonance scattering, which affects the resonance line in the pair but not the intercombination line. This implies that resonance scattering is also important in single resonance lines, where its effect is difficult to distinguish from a low effective continuum optical depth in the wind. Thus, resonance scattering may help reconcile X-ray line profile shapes with literature mass-loss rates.},
  language  = {en}
}
@inproceedings{MassaPrinjaFullerton2007,
  author    = {Massa, D. L. and Prinja, R. K. and Fullerton, A. W.},
  title     = {The effects of clumping on wind line variability},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18095},
  year      = {2007},
  abstract  = {We review the effects of clumping on the profiles of resonance doublets. By allowing the ratio of the doublet oscillator strenghts to be a free parameter, we demonstrate that doublet profiles contain more information than is normally utilized. In clumped (or porous) winds, this ratio can lies between unity and the ratio of the f-values, and can change as a function of velocity and time, depending on the fraction of the stellar disk that is covered by material moving at a particular velocity at a given moment. Using these insights, we present the results of SEI modeling of a sample of B supergiants, ζ Pup and a time series for a star whose terminal velocity is low enough to make the components of its Si VIλλ1400 independent. These results are interpreted within the framewrok of the Oskinova et al. (2007) model, and demonstrate how the doublet profiles can be used to extract infromation about wind structure.},
  language  = {en}
}
@inproceedings{Vink2007,
  author    = {Vink, J. S.},
  title     = {Discussion: Hydrodynamic modeling},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18046},
  year      = {2007},
  language  = {en}
}
@inproceedings{Hillier2007,
  author    = {Hillier, D. J.},
  title     = {On the influence of clumping on O and Wolf-Rayet spectra},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17903},
  year      = {2007},
  abstract  = {Overwhelming observational and theoretical evidence suggests that the winds of massive stars are highly clumped. We briefly discuss the influence of clumping on model diagnostics and the difficulties of allowing for the influence of clumping on model spectra. Because of its simplicity, and because of computational ease, most spectroscopic analyses incorporate clumping using the volume filling factor. The biases introduced by this approach are uncertain. To investigate alternative clumping models, and to help determine the validity of parameters derived using the volume filling factor method, we discuss results derived using an alternative model in which we assume that the wind is composed of optically thick shells.},
  language  = {en}
}
@inproceedings{Fullerton2007,
  author    = {Fullerton, A. W.},
  title     = {Discussion: Spectral modeling},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17917},
  year      = {2007},
  language  = {en}
}
@inproceedings{Townsend2007,
  author    = {Townsend, R. H. D.},
  title     = {Techniques for simulating radiative transfer through porous media},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17866},
  year      = {2007},
  abstract  = {In this contribution, I discuss some basic techniques that can be used to simulate radiative transfer through porous media. As specific examples, I consider scattering transfer through a clumped slab, and X-ray emission line formation in a clumped wind.},
  language  = {en}
}
@inproceedings{udDoula2007,
  author    = {ud-Doula, A.},
  title     = {Large-scale wind structure due to magnetic fields},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18010},
  year      = {2007},
  abstract  = {Magnetic fields influence the dynamics of hot-star winds and create large scale structure. Based on numerical magnetohydrodynamic (MHD) simulations, we model the wind of θ¹ Ori C, and then use the SEI method to compute synthetic line profiles for a range of viewing angles as function of rotational phase. The resulting dynamic spectrum for a moderately strong line shows a distinct modulation, but with a phase that seems at odds with available observations.},
  language  = {en}
}
@inproceedings{IpingSonnebornMassaetal.2007,
  author    = {Iping, R.C. and Sonneborn, G. and Massa, D.L. and Gies, D. and Williams, Simon E.},
  title     = {Far-ultraviolet spectroscopy of O+O binaries in the Magellanic Clouds},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17896},
  year      = {2007},
  abstract  = {We report FUSE observations in 2005-2006 of three O-type, double-lined spectroscopic binaries in the Magellanic Clouds. The systems have very short periods (1.4-2.25 d), represent rare, young evolutionary stages of massive stars and binaries, and provide a unique glimpse at some of the most massive systems that form in dense clusters of massive stars. Improved orbit parameters, including revised masses, for LH54-425 are derived from new ctio spectroscopy. The systems are: LH54-425 in the LMC (O3V + O5V, P=2.25d, 62+37M⊙), J053441-693139 in the LMC (O2-3If+O6V, P=1.4 d, 41+27M⊙), and Hodge 53-47 in the SMC (O6V + O4-5IIIf, P=2.2 d, 24+14M⊙, where the O4 star appears to be less massive than the O6 star). Their short periods indicates that wind interaction and mass transfer are likely important factors in their evolution. The spectra provide quantitative and systematic studies of phase-dependent stellar wind properties, wind collision effects in O+O binaries at lower metallicities, improved radial velocity curves, and FUV spectro-photometric changes as a function of orbital phase.},
  language  = {en}
}
@inproceedings{KustererNagelWerneretal.2007,
  author    = {Kusterer, D.-J. and Nagel, T. and Werner, K. and Feldmeier, Achim},
  title     = {Radiative transfer in CV disk winds},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17847},
  year      = {2007},
  abstract  = {Mass accretion onto compact objects through accretion disks is a common phenomenon in the universe. It is seen in all energy domains from active galactic nuclei through cataclysmic variables (CVs) to young stellar objects. Because CVs are fairly easy to observe, they provide an ideal opportunity to study accretion disks in great detail and thus help us to understand accretion also in other energy ranges. Mass accretion in these objects is often accompanied by mass outflow from the disks. This accretion disk wind, at least in CVs, is thought to be radiatively driven, similar to O star winds. WOMPAT, a 3-D Monte Carlo radiative transfer code for accretion disk winds of CVs is presented.},
  language  = {en}
}
@inproceedings{DaviesVinkOudmaijer2007,
  author    = {Davies, B. and Vink, J. S. and Oudmaijer, R. D.},
  title     = {Modelling the polarimetric variability of hot stars},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17939},
  year      = {2007},
  abstract  = {Many hot stars exhibit stochastic polarimetric variability, thought to arise from clumping low in the wind. Here we investigate the wind properties required to reproduce this variability using analytic models, with particular emphasis on Luminous Blue Variables. We find that the winds must be highly structured, consisting of a large number of optically-thin clumps; while we find that the overall level of polarization should scale with mass-loss rate - consistent with observations of LBVs. The models also predict variability on very short timescales, which is supported by the results of a recent polarimetric monitoring campaign.},
  language  = {en}
}
@inproceedings{KubatSaad2007,
  author    = {Kub{\´a}t, Jiř{\´i} and Saad, S. M.},
  title     = {Moving absorption bumps in the spectra of Be stars},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17879},
  year      = {2007},
  abstract  = {Several Be binaries exhibit an absorption bump moving across the blue wing of hydrogen emission lines towards the line center. This bump is demonstrated for the case of two bright Be stars, κ Dra and 4 Her. It is not clear what is the reason for this travelling bump.},
  language  = {en}
}
@inproceedings{Nielsen2007,
  author    = {Nielsen, K. E.},
  title     = {On irregular line profiles in the optical spectrum of Eta Carinae},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18227},
  year      = {2007},
  abstract  = {The optical spectrum of Eta Carinae (η Car) is prominent in H I, He i and Fe ii wind lines, all of which vary both in absorption and emission with phase. The phase dependance is a consequence of the interaction between the two objects in the η Car binary (η Car A \& B). The binary system is enshrouded by ejecta from previous mass ejection events and consequently, η Car B is not directly observable. We have traced the He i lines over η Car's spectroscopic period, using HST/STIS data obtained with medium spectral, but high angular, resolving power, and created a radial velocity curve for the system. The He I lines are formed in the core of the system, and appear to be a composite of multiple features formed in spatially separated regions. The sources of their irregular line profiles are still not fully understood, but can be attributed to emission/absorption near the wind-wind interface and/or a direct consequence of the η Car A's, massive, clumpy wind. This paper will discuss the spectral variability, the narrow emission structure of the He i lines and how clumpiness of the winds may impede the construction of the reliable radial velocity curve, necessary for characterizations of especially η Car B.},
  language  = {en}
}
@inproceedings{CohenLeuteneggerTownsend2007,
  author    = {Cohen, David H. and Leutenegger, M. A. and Townsend, R. H. D.},
  title     = {Quantitative analysis of resolved X-ray emission line profiles of O stars},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18115},
  year      = {2007},
  abstract  = {By quantitatively fitting simple emission line profile models that include both atomic opacity and porosity to the Chandra X-ray spectrum of ζ Pup, we are able to explore the trade-offs between reduced mass-loss rates and wind porosity. We find that reducing the mass-loss rate of ζ Pup by roughly a factor of four, to 1.5 × 10-6 M⊙ yr-1, enables simple non-porous wind models to provide good fits to the data. If, on the other hand, we take the literature mass-loss rate of 6×10-6 M⊙ yr-1, then to produce X-ray line profiles that fit the data, extreme porosity lengths - of h∞ ≈ 3 R∗ - are required. Moreover, these porous models do not provide better fits to the data than the non-porous, low optical depth models. Additionally, such huge porosity lengths do not seem realistic in light of 2-D numerical simulations of the wind instability.},
  language  = {en}
}
@inproceedings{MorrisonRotherKurschat2007,
  author    = {Morrison, N. D. and Rother, R. and Kurschat, N.},
  title     = {Hα line profile variability in the B8Ia-type supergiant Rigel (β Ori)},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18120},
  year      = {2007},
  abstract  = {Hα observations of Rigel obtained on 184 nights during the past ten years with the 1-m telescope and ´echelle spectrograph of Ritter Observatory are surveyed. The line profiles were classified in terms of morphology. About 1/4 of them are of P Cygni type, about 15\% inverse P Cygni, about 25\% double-peaked, about 1/3 pure absorption, and a few are single emission lines. Transformation of the profile from one type to another typically takes a few days. Although the line stays in absorption for extended intervals, only one high-velocity absorption event of the intensity reported by Kaufer et al. (1996a) was observed, in late 2006. Late in this event, Hα absorption occurred farther to the red than the red wing of a plausible photospheric absorption component, an indication of infalling material. In general, as the absorption events come to an end, the emission typically returns with an inverse P Cygni profile. The Hα profile class shows no obvious correlation with the radial velocity of C II λ6578, a photospheric absorption line.},
  language  = {en}
}
@inproceedings{CheneMoffatCrowther2007,
  author    = {Chen{\´e}, A.-N. and Moffat, Anthony F. J. and Crowther, P. A.},
  title     = {Rapidly accelerating clumps in the winds of the very hot WNE Stars},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18163},
  year      = {2007},
  abstract  = {We study the time variability of emission lines in three WNE stars : WR 2 (WN2), WR 3 (WN3ha) and WR152 (WN3). While WR 2 shows no variability above the noise level, the other stars do show variation, which are like other WR stars in WR 152 but very fast in WR 3. From these motions, we deduce a value of β ∼1 for WR 3 that is like that seen in O stars and β ∼2-3 for WR 152, that is intermediate between other WR stars and WR 3.},
  language  = {en}
}
@inproceedings{Kholtygin2007,
  author    = {Kholtygin, A. F.},
  title     = {Modelling the induced clumping stochastic line profile variability},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18180},
  year      = {2007},
  abstract  = {We model the line profile variability (lpv) in spectra of clumped stellar atmospheres using the Stochastic Clump Model (SCM) of the winds of early-type stars. In this model the formation of dense inhomogeneities (clumps) in the line driven winds is considered as being a stochastic process. It is supposed that the emission due to clumps mainly contributes to the intensities of emission lines in the stellar spectra. It is shown that in the framework of the SCM it is possible to reproduce both the mean line profiles and a common pattern of the lpv.},
  language  = {en}
}
@inproceedings{Cassinelli2007,
  author    = {Cassinelli, Joseph P.},
  title     = {Discussion: Magnetic fields, variability},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18195},
  year      = {2007},
  language  = {en}
}
@inproceedings{StLouis2007,
  author    = {St-Louis, N.},
  title     = {Discussion: Binaries, colliding winds, LBVs and high energy radiation},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18155},
  year      = {2007},
  abstract  = {Clumping in hot-star winds : proceedings of an international workshop held in Potsdam, Germany, 18. - 22. June 2007},
  language  = {en}
}
@inproceedings{RomeroOwockiAraudoetal.2007,
  author    = {Romero, G. E. and Owocki, S. P. and Araudo, A. T. and Townsend, R. H. D. and Benaglia, P.},
  title     = {Using gamma-rays to probe the clumped structure of stellar winds},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18210},
  year      = {2007},
  abstract  = {Gamma-rays can be produced by the interaction of a relativistic jet and the matter of the stellar wind in the subclass of massive X-ray binaries known as "microquasars". The relativistic jet is ejected from the surroundings of the compact object and interacts with cold protons from the stellar wind, producing pions that then quickly decay into gamma-rays. Since the resulting gamma-ray emissivity depends on the target density, the detection of rapid variability in microquasars with GLAST and the new generation of Cherenkov imaging arrays could be used to probe the clumped structure of the stellar wind. In particular, we show here that the relative fluctuation in gamma rays may scale with the square root of the ratio of porosity length to binary separation, \$\sqrt{h/a}\$, implying for example a ca. 10\% variation in gamma ray emission for a quite moderate porosity, h/a ∼ 0.01.},
  language  = {en}
}
@inproceedings{Weis2007,
  author    = {Weis, K.},
  title     = {Wind relics : clumps, inhomogeneities and outflows in LBV nebulae},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18235},
  year      = {2007},
  abstract  = {The most massive stars are those with the shortest but most active life. One group of massive stars, the Luminous Blue Variables (LBVs), of which only a few objects are known, are in particular of interest concerning the stability of stars. They have a high mass loss rate and are close to being instable. This is even more likely as rotation becomes an important factor in stellar evolution of these stars. Through massive stellar winds and sometimes giant eruptions, LBV nebulae are formed. Various aspects in the evolution in the LBV phase lead, beside the large scale morphological and kinematical differences, to a diversity of small structures like clumps, rims, and outflows in these nebulae.},
  language  = {en}
}
@inproceedings{KrtičkaPulsKubat2007,
  author    = {Krtička, Jiri and Puls, Joachim and Kub{\´a}t, Jiř{\´i}},
  title     = {The influence of clumping on predicted O star wind parameters},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17969},
  year      = {2007},
  abstract  = {We study the influence of clumping on the predicted wind structure of O-type stars. For this purpose we artificially include clumping into our stationary wind models. When the clumps are assumed to be optically thin, the radiative line force increases compared to corresponding unclumped models, with a similar effect on either the mass-loss rate or the terminal velocity (depending on the onset of clumping). Optically thick clumps, alternatively, might be able to decrease the radiative force.},
  language  = {en}
}
@inproceedings{KrausKubatKrtička2007,
  author    = {Kraus, M. and Kub{\´a}t, Jiř{\´i} and Krtička, Jiri},
  title     = {Wind emission of OB supergiants and the influence of clumping},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17757},
  year      = {2007},
  abstract  = {The influence of the wind to the total continuum of OB supergiants is discussed. For wind velocity distributions with β > 1.0, the wind can have strong influence to the total continuum emission, even at optical wavelengths. Comparing the continuum emission of clumped and unclumped winds, especially for stars with high β values, delivers flux differences of up to 30\% with maximum in the near-IR. Continuum observations at these wavelengths are therefore an ideal tool to discriminate between clumped and unclumped winds of OB supergiants.},
  language  = {en}
}
@inproceedings{TodtHamannGraefener2007,
  author    = {Todt, Helge Tobias and Hamann, Wolf-Rainer and Gr{\"a}fener, G.},
  title     = {Clumping in [WC]-type Central Stars from electron-scattering line wings},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17711},
  year      = {2007},
  abstract  = {While there is strong evidence for clumping in the winds of massive hot stars, very little is known about clumping in the winds from Central Stars. We have checked [WC]-type CSPN winds for clumping by inspecting the electron-scattering line wings. At least for three stars we found indications for wind inhomogeneities.},
  language  = {en}
}
@inproceedings{FeldmeierHamannRaetzeletal.2007,
  author    = {Feldmeier, Achim and Hamann, Wolf-Rainer and R{\"a}tzel, D. and Oskinova, Lida},
  title     = {Hydrodynamic simulations of clumps},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17975},
  year      = {2007},
  abstract  = {Clumps in hot star winds can originate from shock compression due to the line driven instability. One-dimensional hydrodynamic simulations reveal a radial wind structure consisting of highly compressed shells separated by voids, and colliding with fast clouds. Two-dimensional simulations are still largely missing, despite first attempts. Clumpiness dramatically affects the radiative transfer and thus all wind diagnostics in the UV, optical, and in X-rays. The microturbulence approximation applied hitherto is currently superseded by a more sophisticated radiative transfer in stochastic media. Besides clumps, i.e. jumps in the density stratification, so-called kinks in the velocity law, i.e. jumps in dv/dr, play an eminent role in hot star winds. Kinks are a new type of radiative-acoustic shock, and propagate at super-Abbottic speed.},
  language  = {en}
}
@inproceedings{HamannOskinovaFeldmeier2007,
  author    = {Hamann, Wolf-Rainer and Oskinova, Lida and Feldmeier, Achim},
  title     = {Spectrum formation in clumpy stellar winds},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17838},
  year      = {2007},
  abstract  = {Modeling expanding atmospheres is a difficult task because of the extreme non-LTE situation, the need to account for complex model atoms, especially for the iron-group elements with their millions of lines, and because of the supersonic expansion. Adequate codes have been developed e.g. by Hillier (CMFGEN), the Munich group (Puls, Pauldrach), and in Potsdam (PoWR code, Hamann et al.). While early work was based on the assumption of a smooth and homogeneous spherical stellar wind, the need to account for clumping became obvious about ten years ago. A relatively simple first-order clumping correction was readily implemented into the model codes. However, its simplifying assumptions are severe. Most importantly, the clumps are taken to be optically thin at all frequencies ("microclumping"). We discuss the consequences of this approximation and describe an approach to account for optically thick clumps ("macroclumping"). First results demonstrate that macroclumping can generally reduce the strength of spectral features, depending on their optical thickness. The recently reported discrepancy between the Hα diagnostic and the Pv resonance lines in O star spectra can be resolved without decreasing the mass-loss rates, when macroclumping is taken into account.},
  language  = {en}
}
@inproceedings{OskinovaHamannFeldmeier2007,
  author    = {Oskinova, Lida and Hamann, Wolf-Rainer and Feldmeier, Achim},
  title     = {X-raying clumped stellar winds},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18133},
  year      = {2007},
  abstract  = {X-ray spectroscopy is a sensitive probe of stellar winds. X-rays originate from optically thin shock-heated plasma deep inside the wind and propagate outwards throughout absorbing cool material. Recent analyses of the line ratios from He-like ions in the X-ray spectra of O-stars highlighted problems with this general paradigm: the measured line ratios of highest ions are consistent with the location of the hottest X-ray emitting plasma very close to the base of the wind, perhaps indicating the presence of a corona, while measurements from lower ions conform with the wind-embedded shock model. Generally, to correctly model the emerging Xray spectra, a detailed knowledge of the cool wind opacities based on stellar atmosphere models is prerequisite. A nearly grey stellar wind opacity for the X-rays is deduced from the analyses of high-resolution X-ray spectra. This indicates that the stellar winds are strongly clumped. Furthermore, the nearly symmetric shape of X-ray emission line profiles can be explained if the wind clumps are radially compressed. In massive binaries the orbital variations of X-ray emission allow to probe the opacity of the stellar wind; results support the picture of strong wind clumping. In high-mass X-ray binaries, the stochastic X-ray variability and the extend of the stellar-wind part photoionized by X-rays provide further strong evidence that stellar winds consist of dense clumps.},
  language  = {en}
}
@inproceedings{OPUS4-1574,
  title     = {Clumping in hot-star winds : proceedings of an international workshop held in Potsdam, Germany, 18. - 22. June 2007},
  editor    = {Hamann, Wolf-Rainer and Feldmeier, Achim and Oskinova, Lida},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  isbn      = {978-3-940793-33-1},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-13981},
  pages     = {254},
  year      = {2007},
  abstract  = {Stellar winds play an important role for the evolution of massive stars and their cosmic environment. Multiple lines of evidence, coming from spectroscopy, polarimetry, variability, stellar ejecta, and hydrodynamic modeling, suggest that stellar winds are non-stationary and inhomogeneous. This is referred to as 'wind clumping'. The urgent need to understand this phenomenon is boosted by its far-reaching implications. Most importantly, all techniques to derive empirical mass-loss rates are more or less corrupted by wind clumping. Consequently, mass-loss rates are extremely uncertain. Within their range of uncertainty, completely different scenarios for the evolution of massive stars are obtained. Settling these questions for Galactic OB, LBV and Wolf-Rayet stars is prerequisite to understanding stellar clusters and galaxies, or predicting the properties of first-generation stars. In order to develop a consistent picture and understanding of clumped stellar winds, an international workshop on 'Clumping in Hot Star Winds' was held in Potsdam, Germany, from 18. - 22. June 2007. About 60 participants, comprising almost all leading experts in the field, gathered for one week of extensive exchange and discussion. The Scientific Organizing Committee (SOC) included John Brown (Glasgow), Joseph Cassinelli (Madison), Paul Crowther (Sheffield), Alex Fullerton (Baltimore), Wolf-Rainer Hamann (Potsdam, chair), Anthony Moffat (Montreal), Stan Owocki (Newark), and Joachim Puls (Munich). These proceedings contain the invited and contributed talks presented at the workshop, and document the extensive discussions.},
  language  = {en}
}
@inproceedings{OPUS4-1658,
  title     = {Seelisch gesund von Anfang an : Programm und Abstracts des 26. Symposiums der Fachgruppe Klinische Psychologie und Psychotherapie der Deutschen Gesellschaft f{\"u}r Psychologie, 1. - 3. Mai 2008 in Potsdam},
  editor    = {Warschburger, Petra and Ihle, Wolfgang and Esser, G{\"u}nter},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  isbn      = {978-3-940793-34-8},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17551},
  pages     = {302},
  year      = {2008},
  abstract  = {Der Tagungsband enth{\"a}lt das Programm und die Abstracts des 26. Symposiums der Fachgruppe Klinische Psychologie und Psychotherapie der Deutschen Gesellschaft f{\"u}r Psychologie, veranstaltet an der Universit{\"a}t Potsdam vom 1. bis 3. Mai 2008. Etwa 450 Kongressteilnehmer pr{\"a}sentieren den aktuellen Forschungs- und Wissensstand der Klinischen Psychologie und Psychotherapie in Deutschland. Grußworte halten die brandenburgische Ministerin f{\"u}r Arbeit, Soziales, Gesundheit und Familie, Dagmar Ziegler, die Pr{\"a}sidentin der Universit{\"a}t Potsdam, Prof. Dr.-Ing. Dr. Sabine Kunst, sowie Prof. Dr. Michael Linden als Vertreter der Deutschen Gesellschaft f{\"u}r Psychiatrie, Psychotherapie und Nervenheilkunde (DGPPN). Zu den Themenschwerpunkten des Kongresses geh{\"o}ren Einflussfaktoren auf die psychische Gesundheit {\"A}lterer, Impulsivit{\"a}t, Schlaf- und Traumforschung in der Klinischen Psychologie, Behandlung von Essst{\"o}rungen, Wirksamkeitsstudien psychischer St{\"o}rungen des Kindes- und Jugendalters, Angst und Depression, Behandlung von Kriegs- und Folteropfern, Risiko- und Schutzfaktoren der Kindesentwicklung sowie Adipositas im Kindes- und Jugendalter. Außer den Vortr{\"a}gen gibt es eine Pr{\"a}sentation von etwa 150 Postern. Zum Programm der Tagung geh{\"o}rt ebenso die Verleihung des Klaus-Grawe-Awards for the Advancement of Innovative Research in Clinical Psychology and Psychotherapy an Prof. Dr. Timothy J. Strauman von der Duke University (USA), die Verleihung der Nachwuchswissenschaftler- und Posterpreise sowie ein Pre-conference Workshop f{\"u}r Doktorandinnen und Doktoranden der Klinischen Psychologie zum Thema "Verhaltens- und Molekulargenetik".},
  subject      = {Konferenz},
  language  = {de}
}
@inproceedings{Piskorski2008,
  author    = {Piskorski, Jakub},
  title     = {ExPRESS : extraction pattern recognition engine and specification suite},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-27227},
  year      = {2008},
  abstract  = {The emergence of information extraction (IE) oriented pattern engines has been observed during the last decade. Most of them exploit heavily finite-state devices. This paper introduces ExPRESS - a new extraction pattern engine, whose rules are regular expressions over flat feature structures. The underlying pattern language is a blend of two previously introduced IE oriented pattern formalisms, namely, JAPE, used in the widely known GATE system, and the unificationbased XTDL formalism used in SProUT. A brief and technical overview of ExPRESS, its pattern language and the pool of its native linguistic components is given. Furthermore, the implementation of the grammar interpreter is addressed too.},
  language  = {en}
}
@inproceedings{Neitzel2008,
  author    = {Neitzel, Britta},
  title     = {Metacommunicative circles},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-24647},
  year      = {2008},
  abstract  = {The paper uses Gregory Bateson's concept of metacommunication to explore the boundaries of the 'magic circle' in play and computer games. It argues that the idea of a self-contained "magic circle" ignores the constant negotiations among players which establish the realm of play. The "magic circle" is no fixed ontological entity but is set up by metacommunicative play. The paper further pursues the question if metacommunication could also be found in single-player computer games, and comes to the conclusion that metacommunication is implemented in single-player games by the means of metalepsis.},
  language  = {en}
}
@inproceedings{JennettCoxCairns2008,
  author    = {Jennett, Charlene and Cox, Anna L. and Cairns, Paul},
  title     = {Being "in the game"},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-24682},
  year      = {2008},
  abstract  = {When people describe themselves as being "in the game" this is often thought to mean they have a sense of presence, i.e. they feel like they are in the virtual environment (Brown/Cairns 2004). Presence research traditionally focuses on user experiences in virtual reality systems (e.g. head mounted displays, CAVE-like systems). In contrast, the experience of gaming is very different. Gamers willingly submit to the rules of the game, learn arbitrary relationships between the controls and the screen output, and take on the persona of their game character. Also whereas presence in VR systems is immediate, presence in gaming is gradual. Due to these differences, one can question the extent to which people feel present during gaming. A qualitative study was conducted to explore what gamers actually mean when they describe themselves as being "in the game." Thirteen gamers were interviewed and the resulting grounded theory suggests being "in the game" does not necessarily mean presence (i.e. feeling like you are the character and present in the VE). Some people use this phrase just to emphasize their high involvement in the game. These findings differ with Brown and Cairns as they suggest at the highest state of immersion not everybody experiences presence. Furthermore, the experience of presence does not appear dependent on the game being in the first person perspective or the gamer being able to empathize with the character. Future research should investigate why some people experience presence and others do not. Possible explanations include: use of language, perception of presence, personality traits, and types of immersion.},
  language  = {en}
}
@inproceedings{Mitsuishi2008,
  author    = {Mitsuishi, Yara},
  title     = {Diff{\´e}rance at play : unfolding identities through difference in videogame play},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-24697},
  year      = {2008},
  abstract  = {This paper approaches the debate over the notion of "magic circle" through an exploratory analysis of the unfolding of identities/differences in gameplay through Derrida's diff{\´e}rance. Initially, diff{\´e}rance is related to the notion of play and identity/difference in Derrida's perspective. Next, the notion of magic circle through Derrida's play is analyzed, emphasizing the dynamics of diff{\´e}rance to understand gameplay as process; questioning its boundaries. Finally, the focus shifts toward the implications of the interplay of identities and differences during gameplay.},
  language  = {en}
}
@inproceedings{Watson2008,
  author    = {Watson, Bruce W.},
  title     = {Advances in automata implementation techniques (Abstract)},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-27094},
  year      = {2008},
  language  = {en}
}
@inproceedings{Barthelemy2008,
  author    = {Barth{\´e}lemy, Fran{\c{c}}ois},
  title     = {Finite-state compilation of feature structures for two-level morphology},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-27120},
  year      = {2008},
  abstract  = {This paper describes a two-level formalism where feature structures are used in contextual rules. Whereas usual two-level grammars describe rational sets over symbol pairs, this new formalism uses tree structured regular expressions. They allow an explicit and precise definition of the scope of feature structures. A given surface form may be described using several feature structures. Feature unification is expressed in contextual rules using variables, like in a unification grammar. Grammars are compiled in finite state multi-tape transducers.},
  language  = {en}
}