The B Fields in OB Stars (BOB) Survey

T. Morel (1), N. Castro (2), L. Fossati (2), S. Hubrig (3), N. Langer (2), N. Przybilla (4), M. Schoeller (5), T. Carroll (3), I. Ilyin (3), A. Irrgang (6), L. Oskinova (7), F. R. N. Schneider (2), S. Simon Diaz (8,9), M. Briquet (1), J. F. Gonzalez (10), N. Kharchenko (11), M.-F. Nieva (4,6), R.-D. Scholz (3), A. de Koter (12,13), W.-R. Hamann (7), A. Herrero (8,9), J. Maiz Apellaniz (14), H. Sana (15), R. Arlt (3), R. Barba (16), P. Dufton (17), A. Kholtygin (18), G. Mathys (19), A. Piskunov (20), A. Reisenegger (21), H. Spruit (22), S.-C. Yoon (23)

(1) Institut d'Astrophysique et de Geophysique, Liege, Belgium
(2) Argelander-Institut fuer Astronomie, Bonn, Germany
(3) Leibniz-Institut fuer Astrophysik Potsdam (AIP), Potsdam, Germany
(4) Institute for Astro- and Particle Physics, University of Innsbruck, Austria
(5) European Southern Observatory, Garching, Germany
(6) Dr. Remeis Observatory & ECAP, Bamberg, Germany
(7) Institut fuer Physik und Astronomie der Universitat Potsdam, Germany
(8) Instituto de Astrofisica de Canarias, La Laguna, Spain
(9) Universidad de La Laguna, Dpto. de Astrofisica, La Laguna, Spain
(10) Instituto de Ciencias Astronomicas, de la Tierra, y del Espacio (ICATE), San Juan, Argentina
(11) Main Astronomical Observatory, Kiev, Ukraine
(12) Astronomical Institute Anton Pannekoek, Amsterdam, The Netherlands
(13) Instituut voor Sterrenkunde, Universiteit Leuven, Belgium
(14) Instituto de Astrofisica de Andalucia-CSIC, Granada, Spain
(15) ESA/Space Telescope Science Institute, Baltimore, USA
(16) Departamento de Fisica, La Serena, Chile
(17) Astrophysics Research Centre, Belfast, UK
(18) Chair of Astronomy, Saint-Petersburg State University, Russia
(19) European Southern Observatory, Santiago, Chile
(20) Institute of Astronomy of the Russian Acad. Sci., Moscow, Russia
(21) Pontificia Universidad Catolica de Chile, Santiago, Chile
(22) Max-Planck-Institut fuer Astrophysik, Garching, Germany
(23) Department of Physics and Astronomy, Seoul National University, Seoul, Republic of Korea

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.

Reference: To appear in proceedings of IAU Symposium 307, New Windows on Massive Stars (Geneva, June 2014)
Status: Conference proceedings