TY - JOUR A1 - Aldoretta, E. J. A1 - St-Louis, N. A1 - Richardson, N. D. A1 - Moffat, Anthony F. J. A1 - Eversberg, T. A1 - Hill, G. M. T1 - The Results of the 2013 Pro-Am Wolf-Rayet Campaign JF - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015 N2 - Professional and amateur astronomers around the world contributed to a 4-month long campaign in 2013, mainly in spectroscopy but also in photometry, interferometry and polarimetry, to observe the first 3 Wolf-Rayet stars discovered: WR 134 (WN6b), WR 135 (WC8) and WR 137 (WC7pd+O9). Each of these stars are interesting in their own way, showing a variety of stellar wind structures. The spectroscopic data from this campaign were reduced and analyzed for WR 134 in order to better understand its behavior and long-term periodicity in the context of CIRs in the wind. We will be presenting the results of these spectroscopic data, which include the confirmation of the CIR variability and a time-coherency of ∼ 40 days (half-life of ∼ 20 days). Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-87713 SP - 75 EP - 78 ER - TY - JOUR A1 - Arthur, S. J. T1 - Wolf-Rayet nebulae and the wind-interstellar medium interaction JF - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015 N2 - I review our current understanding of the interaction between a Wolf-Rayet star's fast wind and the surrounding medium, and discuss to what extent the predictions of numerical simulations coincide with multiwavelength observations of Wolf-Rayet nebulae. Through a series of examples, I illustrate how changing the input physics affects the results of the numerical simulations. Finally, I discuss how numerical simulations together with multiwavelength observations of these objects allow us to unpick the previous mass-loss history of massive stars. Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-88267 SP - 315 EP - 320 ER - TY - JOUR A1 - Becker, Andrew C. A1 - Bomans, Dominik J. A1 - Weis, K. T1 - Finding new Wolf-Rayet stars in the Magellanic Clouds JF - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015 N2 - Obtaining a complete census of massive, evolved stars in a galaxy would be a key ingredient for testing stellar evolution models. However, as the evolution of stars is also strongly dependent on their metallicity, it is inevitable to have this kind of data for a variety of galaxies with different metallicities. Between 2009 and 2011, we conducted the Magellanic Clouds Massive Stars and Feedback Survey (MSCF); a spatially complete, multi-epoch, broad- and narrow-band optical imaging survey of the Large and Small Magellanic Clouds. With the inclusion of shallow images, we are able to give a complete photometric catalog of stars between B ≈ 18 and B ≈ 19 mag. These observations were augmented with additional photometric data of similar spatial res- olution from UV to IR (e.g. from GALEX, 2MASS and Spitzer) in order to sample a large portion of the spectral energy distribution of the brightest stars (B < 16 mag) in the Magel- lanic Clouds. Using these data, were are able to train a machine learning algorithm that gives us a good estimate of the spectral type of tens of thousands of stars. This method can be applied to the search for Wolf-Rayet-Stars to obtain a sample of candi- dates for follow-up observations. As this approach can, in principle, be adopted for any resolved galaxy as long as sufficient photometric data is available, it can form an effective alternative method to the classical strategies (e.g. He II filter imaging). Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-87618 SP - 47 EP - 50 ER - TY - JOUR A1 - Beradze, S. A1 - Kochiashvili, N. A1 - Natsvlishvili, R. A1 - Kochiashvili, I. A1 - Janiashvili, E. A1 - Urushadze, T. A1 - Vardosanidze, M. T1 - P Cygni and its Observations at the Abastumani Observatory JF - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015 N2 - We found original observations of PCygni by E. Kharadze and N. Magalashvili in the archives of the Abastumani Observatory. These observations were carried out in the period 1951–1983. Initially they used 29 Cygni as a comparison star, and all observations of PCygni were processed using this star. On the basis of their calculations, the authors decided that PCygni may be a WUMa type binary with an orbital period of 0.500565 d, but this hypothesis was not confirmed. The only observations that have been published in the Bulletin of the Abastumani Astrophysical Observatory were those of of 1951–1955. There are whole sets of observational data not only for PCygni and 29 Cygni, but in the majority of cases also for 36 Cygni in the archives. We recalculated all data (where it was possible) using 36 Cygni as a comparison star. We are presenting UBV light curves of the variable, and also observations made by V. Nikonov in Abastumani in the period 1935–1937 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-88389 SP - 353 ER - TY - JOUR A1 - Bestenlehner, J. M. T1 - Stellar parameters from photometric data for fainter and more distant Wolf-Rayet stars JF - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015 N2 - Spectroscopy is the preferred way to study the physical and wind properties of Wolf-Rayet (WR) stars, but with decreasing brightness and increasing distance of the object spectroscopy become very expensive. However, photometry still delivers a high signal to noise ratio. Current and past astronomical surveys and space missions provide large data sets, that can be harvested to discover new WR stars and study them over a wide metallicity range with the help of state of the art stellar atmosphere and evolutionary models. Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-88390 SP - 354 ER - TY - JOUR A1 - Bibby, J. A1 - Shara, M. A1 - Zurek, D. A1 - Crowther, P. A. A1 - Moffat, Anthony F. J. A1 - Drissen, L. A1 - Wilde, M. T1 - The Distribution of Massive Stars in M101 JF - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015 N2 - 75 WR stars and 164 RSGs are identified in a single WFC3 pointing of our M101 survey. We find that within it's large star-forming complex NGC 5462 WR stars are preferentially located in the core whilst RSGs are found in the halo, suggesting two bursts of star-formation. A review of our WR candidates reveals that only ∼30% are detected in the archival broad-band ACS imaging whilst only ∼50% are associated with HII regions. Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-88402 SP - 355 ER - TY - JOUR A1 - Bomans, Dominik J. A1 - Becker, Andrew C. A1 - Kleemann, B. A1 - Weis, K. A1 - Pasquali, A. T1 - Luminous Wolf-Rayet stars at low metallicity JF - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015 N2 - The evolution of massive stars in very low metallicity galaxies is less well observationally constrained than in environments more similar to the Milky Way, M33, or the LMC. We discuss in this contribution the current state of our program to search for and characterize Wolf-Rayet stars (and other massive emission line stars) in low metallicity galaxies in the Local Volume. Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-87635 SP - 51 EP - 54 ER - TY - JOUR A1 - Calderón, D. A1 - Ballone, A. A1 - Cuadra, J. A1 - Schartmann, M. A1 - Burkert, Andreas A1 - Gillessen, S. T1 - Formation of the infalling Galactic Centre cloud G2 by collision of stellar winds JF - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015 N2 - The gas cloud G2 is currently being tidally disrupted by the Galactic Centre super-massive black hole, Sgr A*. The region around the black hole is populated by ∼ 30 Wolf-Rayet stars, which produce strong outflows. Here we explore the possibility that gas clumps like G2 originate from the collision of stellar winds via the non-linear thin shell instability. Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-88412 SP - 356 ER - TY - JOUR A1 - Chené, A.-N. A1 - Wyrick, D. A1 - Borissova, J. A1 - Kuhn, M. A1 - Hervé, A. A1 - Ramírez Alegría, S. A1 - Bonatto, C. A1 - Bouret, J.-C. A1 - Kurtev, R. T1 - Improving distances to Galactic Wolf-Rayet stars JF - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015 N2 - Before GAIA improves the HIPPARCOS survey, direct determination of the distance via parallax is only possible for γ Vel, but the analysis of the cluster or association to which WR stars are associated can give distances with a 50% to a 10% accuracy. The list of Galactic clusters, associations and clusters/association candidates has grown significantly in the last decade with the numerous deep, high resolution surveys of the Milky Way. In this work, we revisit the fundamental parameters of known clusters with WR stars, and we present the search for new ones. All our work is based on the catalogs from the VVV (from the VISTA telescope) and the UKIDS (from the UKIRT telescope) near infrared surveys. Finally, the relations between the fundamental parameters of clusters with WR stars are explored. Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-87759 SP - 97 EP - 100 ER - TY - JOUR A1 - Cherchneff, I. T1 - Dust formation in carbon-rich Wolf-Rayet colliding winds JF - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015 N2 - Carbon-rich Wolf-Rayet stars are efficient carbon dust makers. Despite the strong evidence for dust formation in these objects provided by infrared thermal emission from dust, the routes to nucleation and condensation and the physical conditions required for dust production are still poorly understood. We discuss here the potential routes to carbon dust and the possible locations conducive to dust formation in the colliding winds of WC binaries. Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-88177 SP - 269 EP - 274 ER -