@article{EvansvanLoonHainichetal.2015,
  author    = {Evans, Chris J. and van Loon, Jacco Th and Hainich, Rainer and Bailey, M.},
  title     = {2dF-AAOmega spectroscopy of massive stars in the Magellanic Clouds The north-eastern region of the Large Magellanic Cloud},
  series = {Astronomy and astrophysics : an international weekly journal},
  volume    = {584},
  journal   = {Astronomy and astrophysics : an international weekly journal},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  issn      = {1432-0746},
  doi       = {10.1051/0004-6361/201525882},
  pages     = {19},
  year      = {2015},
  abstract  = {We present spectral classifications from optical spectroscopy of 263 massive stars in the north-eastern region of the Large Magellanic Cloud. The observed two-degree field includes the massive 30 Doradus star-forming region, the environs of SN1987A, and a number of star-forming complexes to the south of 30 Dor. These are the first classifications for the majority (203) of the stars and include eleven double-lined spectroscopic binaries. The sample also includes the first examples of early OC-type spectra (AA Omega 30 Dor 248 and 280), distinguished by the weakness of their nitrogen spectra and by C IV lambda 4658 emission. We propose that these stars have relatively unprocessed CNO abundances compared to morphologically normal O-type stars, indicative of an earlier evolutionary phase. From analysis of observations obtained on two consecutive nights, we present radial-velocity estimates for 233 stars, finding one apparent single-lined binary and nine (>3 sigma) outliers compared to the systemic velocity; the latter objects could be runaway stars or large-amplitude binary systems and further spectroscopy is required to investigate their nature.},
  language  = {en}
}
@article{HubrigSchoellerIlyinetal.2013,
  author    = {Hubrig, Swetlana and Schoeller, M. and Ilyin, Ilya and Kharchenko, N. V. and Oskinova, Lida and Langer, N. and Gonzalez, J. F. and Kholtygin, A. F. and Briquet, Maryline},
  title     = {Exploring the origin of magnetic fields in massive stars - II. New magnetic field measurements in cluster and field stars},
  series = {Astronomy and astrophysics : an international weekly journal},
  volume    = {551},
  journal   = {Astronomy and astrophysics : an international weekly journal},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  organization    = {MAGORI Collaboration},
  issn      = {0004-6361},
  doi       = {10.1051/0004-6361/201220721},
  pages     = {13},
  year      = {2013},
  abstract  = {Context. Theories on the origin of magnetic fields in massive stars remain poorly developed, because the properties of their magnetic field as function of stellar parameters could not yet be investigated. Additional observations are of utmost importance to constrain the conditions that are conducive to magnetic fields and to determine first trends about their occurrence rate and field strength distribution. Aims. To investigate whether magnetic fields in massive stars are ubiquitous or appear only in stars with a specific spectral classification, certain ages, or in a special environment, we acquired 67 new spectropolarimetric observations for 30 massive stars. Among the observed sample, roughly one third of the stars are probable members of clusters at different ages, whereas the remaining stars are field stars not known to belong to any cluster or association. Methods. Spectropolarimetric observations were obtained during four different nights using the low-resolution spectropolarimetric mode of FOcal Reducer low dispersion Spectrograph (FORS 2) mounted on the 8-m Antu telescope of the VLT. Furthermore, we present a number of follow-up observations carried out with the high-resolution spectropolarimeters SOFIN mounted at the Nordic Optical Telescope (NOT) and HARPS mounted at the ESO 3.6 m between 2008 and 2011. To assess the membership in open clusters and associations, we used astrometric catalogues with the highest quality kinematic and photometric data currently available. Results. The presence of a magnetic field is confirmed in nine stars previously observed with FORS 1/2: HD36879, HD47839, CPD-28 2561, CPD-47 2963, HD93843, HD148937, HD149757, HD328856, and HD164794. New magnetic field detections at a significance level of at least 3 sigma were achieved in five stars: HD92206c, HD93521, HD93632, CPD-46 8221, and HD157857. Among the stars with a detected magnetic field, five stars belong to open clusters with high membership probability. According to previous kinematic studies, five magnetic O-type stars in our sample are candidate runaway stars.},
  language  = {en}
}