Searching for the presence of a weak magnetic field in the Be star λ Eri using FORS 2 spectropolarimetric time series.

The presence of magnetic fields in Be stars is highly controversial and still under debate. In this work, we report the results of our search for the presence of a magnetic field and its short-time variability in the well-known non-radially-pulsating single bright Be star λ Eri using several low-resolution spectropolarimetric time series obtained with the ESO FORS 1/2 instruments in 2006, 2007, and, most recently, in 2016. The longitudinal magnetic field for the individual measurements, each using a combination of observations with the quarter-wave plate positions +45° and −45°, oscillates between +470 and −540 G with rather high standard errors of the measurements, up to 200-300 G. Still, a few measurements indicate the presence of a signal at 2.5-4 σ significance. A search for periodicity in the time series from 2006 to 2016 indicates the potential presence of a magnetic variability modulation with a period of ∼13.7 min, which possibly can be taken as a hint for the presence of a small-scale magnetic field on the stellar surface. [ABSTRACT FROM AUTHOR]