EDP Sciences
Free access
Volume 466, Number 2, May I 2007
Page(s) L13 - L16
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20077095

A&A 466, L13-L16 (2007)
DOI: 10.1051/0004-6361:20077095


Rapid magnetic flux variability on the flare star CN Leonis

A. Reiners1, 2, J. H. M. M. Schmitt1, and C. Liefke1

1  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

(Received 15 January 2007 / Accepted 28 February 2007)

We present UVES/VLT observations of the nearby flare star CN Leo covering the Wing-Ford FeH band near 1 $\mu$m 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 $\approx$ 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