Super-Eddington mechanical power of an accreting black hole in M83.

Mass accretion onto black holes releases energy in the form of radiation and outflows. Although the radiative flux cannot substantially exceed the Eddington limit, at which the outgoing radiation pressure impedes the inflow of matter, it remains unclear whether the kinetic energy flux is bounded by this same limit. Here, we present the detection of a radio-optical structure, powered by outflows from a non-nuclear black hole. Its accretion disk properties indicate that this black hole is less than 100 solar masses. The optical-infrared line emission implies an average kinetic power of 3 × 10(40) erg second(-1), higher than the Eddington luminosity of the black hole. These results demonstrate kinetic power exceeding the Eddington limit over a sustained period, which implies greater ability to influence the evolution of the black hole's environment.

Deficiency of molecular hydrogen in the disk of beta Pictoris.

Molecular hydrogen (H2) is by far the most abundant material from which stars, protoplanetary disks and giant planets form, but it is difficult to detect directly. Infrared emission lines from H2 have recently been reported towards beta Pictoris, a star harbouring a young planetary system. This star is surrounded by a dusty 'debris disk' that is continuously replenished either by collisions between asteroidal objects or by evaporation of ices on Chiron-like objects. A gaseous disk has also been inferred from absorption lines in the stellar spectrum. Here we present the far-ultraviolet spectrum of beta Pictoris, in which H2 absorption lines are not seen. This allows us to set a very low upper limit on the column density of H2: N(H2) 6 x 10-4. As CO would be destroyed under ambient conditions in about 200 years (refs 9, 11), our result demonstrates that the CO in the disk arises from evaporation of planetesimals.

The moving emission features in SS433 require a dynamical interpretation.

New spectrophotometry of SS433 shows that the variable-wavelength emission features discovered by Margon et al. are due to the simultaneous presence of material having a substantial redshift and a substantial blueshift. A magnetic interpretation for the features is also ruled out by polarimetric measurements. Implications for dynamical models are discussed.