A magnetic cycle of tau Bootis? The coronal and chromospheric view

TL;DR

This study investigates tau Bootis's magnetic activity cycle through X-ray and optical observations, finding no evidence for the previously hypothesized one-year cycle despite earlier spectropolarimetric suggestions.

Contribution

The paper provides new observational data that challenge prior claims of a rapid magnetic cycle in tau Bootis, offering a more comprehensive view of its stellar activity.

Findings

No evidence of a one-year magnetic activity cycle

X-ray and optical data do not support previous spectropolarimetric results

Results suggest a longer or different cycle than previously hypothesized

Abstract

Tau Bootis is a late F-type main sequence star orbited by a Hot Jupiter. During the last years spectropolarimetric observations led to the hypothesis that this star may host a global magnetic field that switches its polarity once per year, indicating a very short activity cycle of only one year duration. In our ongoing observational campaign, we have collected several X-ray observations with XMM-Newton and optical spectra with TRES/FLWO in Arizona to characterize tau Boo's corona and chromosphere over the course of the supposed one-year cycle. Contrary to the spectropolarimetric reconstructions, our observations do not show indications for a short activity cycle.