Magnetometry of a sample of massive stars in Carina

Y. Naze (1), S. Bagnulo (2), V. Petit (3), T. Rivinius (4), G. Wade (5), G. Rauw (1), M. Gagne (3)

1-ULg, 2-Armagh Obs., 3-West Chester Un., 4-ESO, 5-RMC

X-ray surveys of the Carina nebula have revealed a few hard and luminous sources associated with early-type stars. Such unusual characteristics for the high-energy emission may be related to magnetically-confined winds. To search for the presence of magnetic fields in these objects, we performed a limited spectropolarimetric survey using the FORS instrument. The multi-object mode was used, so that a total of 21 OB stars could be investigated during a one-night-long run. A magnetic field was detected in two objects of the sample, with a 6 sigma significance; Tr16-22 and 13. Such a detection was expected for Tr16-22, as its X-ray emission is too bright, variable and hard, compared to other late-type O or O+OB systems. It is more surprising for Tr16-13, a poorly known star which so far has never shown any peculiar characteristics. Subsequent monitoring is now needed to ascertain the physical properties of these objects and enable a full modelling of their magnetic atmospheres and winds.

Reference: accepted by MNRAS
Status: Manuscript has been accepted