Volume 471, Number 1, August III 2007
|Page(s)||L5 - L8|
|Published online||26 June 2007|
Letter to the Editor
Spectral-type dependent rotational braking and strong magnetic flux in three components of the late-M multiple system LHS 1070
Universität Göttingen, Institut für Astrophysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany e-mail: Ansgar.Reiners@phys.uni-goettingen.de
2 Universität Jena, Astrophysikalisches Institut und Instituts-Sternwarte, Schillergässchen 2, 07745 Jena, Germany
3 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
4 European Southern Observatory, Alonso de Córdova 3107, Casilla 19001, Santiago 19, Chile
Accepted: 14 June 2007
We show individual high-resolution spectra of components A, B, and C of the nearby late-M type multiple system LHS 1070. Component A is a mid-M star, and B and C are known to have masses at the threshold to brown dwarfs. From our spectra we measure rotation velocities and the mean magnetic field for all three components individually. We find magnetic flux on the order of several kilo-Gauss in all components. The rotation velocities of the two late-M objects B and C are similar (v sini = 16 km s-1), the earlier A component is spinning only at about half that rate. This suggest that net rotational braking at late-M spectral type is weakening, and that the lack of slowly rotating late-M and L dwarfs is real. Furthermore, we found that magnetic flux in the B component is about twice as strong as in component C at a similar rotation rate. This indicates that rotational braking is not proportional to magnetic field strength in fully convective objects and that a different field topology is the reason for the weak braking in low-mass objects.
Key words: stars: low-mass, brown dwarfs / stars: magnetic fields / stars: rotation / stars: individual: LHS 1070
© ESO, 2007
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.