Ultra-Cool and Extra-Vigorous: Rotation and Activity in M and L dwarfs

Abstract

The study of rotation and activity in low-mass stars or brown dwarfs of spectral classes M and L has seen enormous progress during the last years. I summarize the results from different works that measured activity, rotation, and sometimes magnetic fields. The generation of magnetic activity seems to be unchanged at the threshold to completely convective stars, i.e. no change in the efficiency of the magnetic dynamos is observed. On the other hand, a sudden change in the strength of rotational braking appears at the threshold mass to full convection, and strong evidence exists for rotational braking weakening with lower mass. A probable explanation is that the field topology changes from dipolar to small scale structure as the objects become fully convective.

arXiv comment3 pages, talk given at the 5th Potsdam Thinkshop, accepted by AN

References in corpus (8)

• Rotation and Activity in Mid-M to L Dwarfs
• Spectroscopic Properties of Cool Stars in the SDSS: An Analysis of Magnetic Activity and a Search for Subdwarfs
• The First Direct Measurements of Magnetic Fields on Very Low-Mass Stars
• Activity in Very Cool Stars: Magnetic Dissipation in late-M and L Dwarf Atmospheres
• The Narrowest M-dwarf Line Profiles and the Rotation-Activity Connection at Very Slow Rotation
• A Search for Variability in the Active T dwarf 2MASS 1237+6526
• The First High-Resolution Spectra of 1.3 L Subdwarfs
• Spectral type dependent rotational braking and strong magnetic flux in three components of the late-M multiple system LHS 1070

Cited by in corpus (4)

• On the evolutionary status of short period cataclysmic variables
• On a transition from solar-like coronae to rotation-dominated jovian-like magnetospheres in ultracool main-sequence stars
• The Rotation of M Dwarfs Observed by the Apache Point Galactic Evolution Experiment
• A J-band detection of the sub-stellar mass donor in SDSS J1433+1011