Magnetometry of a sample of massive stars in Carina

TL;DR

This study used spectropolarimetry to detect magnetic fields in massive stars in Carina, revealing magnetic activity in two stars, which may explain their unusual X-ray emissions.

Contribution

First detection of magnetic fields in two massive stars in Carina using spectropolarimetry, expanding understanding of stellar magnetism in such objects.

Findings

Magnetic field detected in Tr16-22 and Tr16-13 with high significance.

Tr16-22's magnetic detection aligns with its X-ray properties.

Tr16-13's magnetic detection suggests new magnetic phenomena in poorly known stars.

Abstract

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.