Letter to the Editor
Rapid magnetic flux variability on the flare star CN Leonis*
Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany e-mail: [jschmitt;cliefke]@hs.uni-hamburg.de
2 Universität Göttingen, Institut für Astrophysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany e-mail: Ansgar.Reiners@phys.uni-goettingen.de
Accepted: 28 February 2007
We present UVES/VLT observations of the nearby flare star CN Leo covering the Wing-Ford FeH band near 1 μm with high spectral resolution. Some of the FeH absorption lines in this band are magnetically sensitive and allow a measurement of the mean magnetic flux on CN Leo. Our observations, covering three nights separated by 48 hours each, allow a clear detection of a mean magnetic field of Bf ≈ 2.2 kG. The differential flux measurements show a night-to-night variability with extremely high significance. Finally, our data strongly suggest magnetic flux variability on time scales as low as 6 hours in line with chromospheric variability.
Key words: stars: activity / stars: late-type / stars: magnetic fields / stars: individual: CN Leo
© ESO, 2007