@inproceedings{Reimer2007,
  author    = {Reimer, A.},
  title     = {Clumping effects on non-thermal particle spectra in massive star systems},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18246},
  year      = {2007},
  abstract  = {Observational evidence exists that winds of massive stars are clumped. Many massive star systems are known as non-thermal particle production sites, as indicated by their synchrotron emission in the radio band. As a consequence they are also considered as candidate sites for non-thermal high-energy photon production up to gamma-ray energies. The present work considers the effects of wind clumpiness expected on the emitting relativistic particle spectrum in colliding wind systems, built up from the pool of thermal wind particles through diffusive particle acceleration, and taking into account inverse Compton and synchrotron losses. In comparison to a homogeneous wind, a clumpy wind causes flux variations of the emitting particle spectrum when the clump enters the wind collision region. It is found that the spectral features associated with this variability moves temporally from low to high energy bands with the time shift between any two spectral bands being dependent on clump size, filling factor, and the energy-dependence of particle energy gains and losses.},
  language  = {en}
}
@inproceedings{SchnurrCrowther2007,
  author    = {Schnurr, O. and Crowther, P. A.},
  title     = {Mid-IR observations of WC stars, and the connection to wind clumping},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17884},
  year      = {2007},
  abstract  = {We present preliminary results of a tailored atmosphere analysis of six Galactic WC stars using UV, optical, and mid-infrared Spitzer IRS data. With these data, we are able to sample regions from 10 to 10³ stellar radii, thus to determine wind clumping in different parts of the wind. Ultimately, derived wind parameters will be used to accuratelymeasure neon abundances, and to so test predicted nuclear-reaction rates.},
  language  = {en}
}
@inproceedings{VinkBenagliaDaviesetal.2007,
  author    = {Vink, J. S. and Benaglia, P. and Davies, B. and de Koter, A. and Oudmaijer, R. D.},
  title     = {Advances in mass-loss predictions},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17948},
  year      = {2007},
  abstract  = {We present the results of Monte Carlo mass-loss predictions for massive stars covering a wide range of stellar parameters. We critically test our predictions against a range of observed massloss rates - in light of the recent discussions on wind clumping. We also present a model to compute the clumping-induced polarimetric variability of hot stars and we compare this with observations of Luminous Blue Variables, for which polarimetric variability is larger than for O and Wolf-Rayet stars. Luminous Blue Variables comprise an ideal testbed for studies of wind clumping and wind geometry, as well as for wind strength calculations, and we propose they may be direct supernova progenitors.},
  language  = {en}
}
@inproceedings{MoffatHillierHamannetal.2007,
  author    = {Moffat, Anthony F. J. and Hillier, D. J. and Hamann, Wolf-Rainer and Owocki, S. P.},
  title     = {General Discussion},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17953},
  year      = {2007},
  abstract  = {Clumping in hot-star winds : proceedings of an international workshop held in Potsdam, Germany, 18. - 22. June 2007},
  language  = {en}
}
@inproceedings{Sonneborn2007,
  author    = {Sonneborn, G.},
  title     = {Imaging and spectroscopy with the James Webb Space Telescope},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17983},
  year      = {2007},
  abstract  = {The James Webb Space Telescope (JWST) is a large, infrared-optimized space telescope scheduled for launch in 2013. JWST will find the first stars and galaxies that formed in the early universe, connecting the Big Bang to our own Milky Way galaxy. JWST will peer through dusty clouds to see stars forming planetary systems, connecting the MilkyWay to our own Solar System. JWST's instruments are designed to work primarily in the infrared range of 1 - 28 μm, with some capability in the visible range. JWST will have a large mirror, 6.5 m in diameter, and will be diffraction-limited at 2 μm (0.1 arcsec resolution). JWST will be placed in an L2 orbit about 1.5 million km from the Earth. The instruments will provide imaging, coronography, and multi-object and integral-field spectroscopy across the 1 - 28 μm wavelength range. The breakthrough capabilities of JWST will enable new studies of massive star winds from the Milky Way to the early universe.},
  language  = {en}
}
@inproceedings{Owocki2007,
  author    = {Owocki, S. P.},
  title     = {Dynamical simulation of the "velocity-porosity" reduction in observed strength of stellar wind lines},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17992},
  year      = {2007},
  abstract  = {I use dynamical simulations of the line-driven instability to examine the potential role of the resulting flow structure in reducing the observed strength of wind absorption lines. Instead of the porosity length formalism used to model effects on continuum absorption, I suggest reductions in line strength can be better characterized in terms of a velocity clumping factor that is insensitive to spatial scales. Examples of dynamic spectra computed directly from instability simulations do exhibit a net reduction in absorption, but only at a modest 10-20\% level that is well short of the ca. factor 10 required by recent analyses of PV lines.},
  language  = {en}
}
@inproceedings{Blomme2007,
  author    = {Blomme, R.},
  title     = {Corotating Interaction Regions and clumping},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18100},
  year      = {2007},
  abstract  = {We present hydrodynamical models for Corotating Interaction Regions, which were used by Lobel (2007) to model the Discrete Absorption Components in HD 64760. We also discuss our failure to model the rotational modulations seen in the same star.},
  language  = {en}
}
@inproceedings{Kholtygin2007,
  author    = {Kholtygin, A. F.},
  title     = {Wavelets for looking for clumping in the wind of OB stars},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17796},
  year      = {2007},
  abstract  = {Clumping in hot-star winds : proceedings of an international workshop held in Potsdam, Germany, 18. - 22. June 2007},
  language  = {en}
}
@inproceedings{UrbanejaKudritzkiPuls2007,
  author    = {Urbaneja, M. A. and Kudritzki, R.-P. and Puls, Joachim},
  title     = {Clumping in the winds of O-type CSPNs},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17801},
  year      = {2007},
  abstract  = {Recent studies of massive O-type stars present clear evidences of inhomogeneous and clumped winds. O-type (H-rich) central stars of planetary nebulae (CSPNs) are in some ways the low mass-low luminosity analogous of those massive stars. In this contribution, we present preliminary results of our on-going multi-wavelength (FUV, UV and optical) study of the winds of Galactic CSPNs. Particular emphasis will be given to the clumping factors derived by means of optical lines (Hα and Heii 4686) and "classic" FUV (and UV) lines.},
  language  = {en}
}
@inproceedings{deKoterVinkMuijres2007,
  author    = {de Koter, A. and Vink, J. S. and Muijres, L.},
  title     = {Constraints on wind clumping from the empirical mass-loss vs. metallicity relation for early-type stars},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17736},
  year      = {2007},
  abstract  = {We present the latest results on the observational dependence of the mass-loss rate in stellar winds of O and early-B stars on the metal content of their atmospheres, and compare these with predictions. Absolute empirical rates for the mass loss of stars brighter than 10\$^{5.2} L_{\odot}\$, based on H\$\alpha\$ and ultraviolet (UV) wind lines, are found to be about a factor of two higher than predictions. If this difference is attributed to inhomogeneities in the wind this would imply that luminous O and early-B stars have clumping factors in their H\$\alpha\$ and UV line forming regime of about a factor of 3--5. The investigated stars cover a metallicity range \$Z\$ from 0.2 to 1 \$Z_{\odot}\$. We find a hint towards smaller clumping factors for lower \$Z\$. The derived clumping factors, however, presuppose that clumping does not impact the predictions of the mass-loss rate. We discuss this assumption and explain how we intend to investigate its validity in more detail.},
  language  = {en}
}