P hotosynthetic organisms come in all shapes and sizes. From a human perspective, the trees and plants of dry land are the most conspicuous examples, but the next time you admire a colorful tulip or marvel at the girth of a giant Sequoia, consider the following: Approximately half of the oxygen we breathe is generated by singlecelled photosynthesizers, phytoplankton, adrift in the world’s ocean...

ISO observations will improve our understanding of disks around low-mass pre-main–sequence stars in various ways. In particular, ISO can measure simultaneously spectral energy distributions and lowresolution spectra from 2 to 12 μm of T Tauri stars with greater sensitivity, greater spectral coverage and finer spectral resolution than available in ground-based observations or with IRAS. We illus...

We present a precise kinematic study of very young brown dwarfs in the Cha I cloud based on radial velocities (RVs) measured with UVES at the VLT. The kinematics of the brown dwarfs in Cha I are compared to the kinematics of T Tauri stars in the same field based on UVES measurements for very low-mass ones and based on RVs from the literature. In comparison with a former paper (Joergens & Guenth...

We propose that FU Orionis outbursts may play an important role in maintaining the slow rotation of classical disk-accreting T Tauri stars. Current estimates for the frequency and duration of FU Orionis outbursts and the mass accretion rates of T Tauri and FU Orionis stars suggest that more mass may be accreted during the outbursts than during the T Tauri phases. If this is the case, then the o...

The basal position of the Mamiellales (Prasinophyceae) within the green lineage makes these unicellular organisms key to elucidating early stages in the evolution of chlorophyll a/b-binding light-harvesting complexes (LHCs). Here, we unveil the complete and unexpected diversity of Lhc proteins in Ostreococcus tauri, a member of the Mamiellales order, based on results from complete genome sequen...

Magnetic activity phenomena are characteristic for T-Tauri stars as well as protostellar class I objects. A model for the flare-like emissivity based on a macroscopic plasma instability, the resistive tearing mode, is proposed. The dispersion relation for the unstable modes for the appropriate partially ionized dusty plasma regime is presented and solved numerically. The results indicate that t...