@article{ShenarRichardsonSablowskietal.2017, author = {Shenar, Tomer and Richardson, N. D. and Sablowski, Daniel P. and Hainich, Rainer and Sana, H. and Moffat, A. F. J. and Todt, Helge Tobias and Hamann, Wolf-Rainer and Oskinova, Lida and Sander, Andreas Alexander Christoph and Tramper, Frank and Langer, Norbert and Bonanos, Alceste Z. and de Mink, Selma E. and Gr{\"a}fener, G. and Crowther, Paul and Vink, J. S. and Almeida, Leonardo A. and de Koter, A. and Barb{\´a}, Rodolfo and Herrero, A. and Ulaczyk, Krzysztof}, title = {The tarantula massive binary monitoring}, series = {Astronomy and astrophysics : an international weekly journal}, volume = {598}, journal = {Astronomy and astrophysics : an international weekly journal}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {1432-0746}, doi = {10.1051/0004-6361/201629621}, pages = {16}, year = {2017}, abstract = {We present the first SB2 orbital solution and disentanglement of the massive Wolf-Rayet binary R145 (P = 159 d) located in the Large Magellanic Cloud. The primary was claimed to have a stellar mass greater than 300 M-circle dot, making it a candidate for being the most massive star known to date. While the primary is a known late-type, H-rich Wolf-Rayet star (WN6h), the secondary has so far not been unambiguously detected. Using moderate-resolution spectra, we are able to derive accurate radial velocities for both components. By performing simultaneous orbital and polarimetric analyses, we derive the complete set of orbital parameters, including the inclination. The spectra are disentangled and spectroscopically analyzed, and an analysis of the wind-wind collision zone is conducted. The disentangled spectra and our models are consistent with a WN6h type for the primary and suggest that the secondary is an O3.5 If*/WN7 type star. We derive a high eccentricity of e = 0 : 78 and minimum masses of M-1 sin(3) i approximate to M-2 sin(3) i = 13 +/- 2 M-circle dot, with q = M-2/M-1 = 1.01 +/- 0.07. An analysis of emission excess stemming from a wind-wind collision yields an inclination similar to that obtained from polarimetry (i = 39 +/- 6 degrees). Our analysis thus implies M-1 = 53(-20)(+40) and M2 = 54(-20)(+40) M-circle dot, excluding M-1 > 300 M-circle dot. A detailed comparison with evolution tracks calculated for single and binary stars together with the high eccentricity suggests that the components of the system underwent quasi-homogeneous evolution and avoided mass-transfer. This scenario would suggest current masses of approximate to 80 M-circle dot and initial masses of M-i,M-1 approximate to 10(5) and M-i,M-2 approximate to 90 M-circle dot, consistent with the upper limits of our derived orbital masses, and would imply an age of approximate to 2.2 Myr.}, language = {en} } @misc{MorelCastroFossatietal.2014, author = {Morel, T. and Castro, Norberto and Fossati, Luca and Hubrig, Swetlana and Langer, N. and Przybilla, Norbert and Sch{\"o}ller, Markus and Carroll, Thorsten Anthony and Ilyin, Ilya and Irrgang, Andreas and Oskinova, Lida and Schneider, Fabian R. N. and Simon D{\´i}az, Sergio and Briquet, Maryline and Gonz{\´a}lez, Jean-Francois and Kharchenko, Nina and Nieva, M.-F. and Scholz, Ralf-Dieter and de Koter, Alexander and Hamann, Wolf-Rainer and Herrero, Artemio and Ma{\´i}z Apell{\´a}niz, Jesus and Sana, Hugues and Arlt, Rainer and Barb{\´a}, Rodolfo H. and Dufton, Polly and Kholtygin, Alexander and Mathys, Gautier and Piskunov, Anatoly E. and Reisenegger, Andreas and Spruit, H. and Yoon, S.-C.}, title = {The B fields in OB stars (BOB) survey}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {821}, issn = {1866-8372}, doi = {10.25932/publishup-41523}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-415238}, pages = {8}, year = {2014}, abstract = {The B fields in OB stars (BOB) survey is an ESO large programme collecting spectropolarimetric observations for a large number of early-type stars in order to study the occurrence rate, properties, and ultimately the origin of magnetic fields in massive stars. As of July 2014, a total of 98 objects were observed over 20 nights with FORS2 and HARPSpol. Our preliminary results indicate that the fraction of magnetic OB stars with an organised, detectable field is low. This conclusion, now independently reached by two different surveys, has profound implications for any theoretical model attempting to explain the field formation in these objects. We discuss in this contribution some important issues addressed by our observations (e.g., the lower bound of the field strength) and the discovery of some remarkable objects.}, language = {en} }