The interplanetary magnetic structure that guides... (Masson et al.) Wednesday, 25 January 2012 08:00 Vol. 538 In section 9. The Sun The interplanetary magnetic structure that guides solar relativistic particles by S. Masson, P. Démoulin, S. Dasso, and K.-L. Klein, A&A 538, A32 High-energy particles originating from the Sun led to a nuclear cascade in the Earth atmosphere that can finally be detected by a neutron monitor on the ground. By studying the timing of enhancements detected by the neutron monitors, the authors were able to connect time delays to the spatial structure of (interplanetary) coronal mass ejections. This indicates that these coronal mass ejections exhibit 'wound-up' magnetic fields leading to longer path lengths, hence longer travel times for the energetic particles from the Sun.   Quasar feedback quenching star formation at high redshift (Cano-Diaz et al.) Tuesday, 17 January 2012 08:00 Vol. 537 In section 1. Letters Observational evidence of quasar feedback quenching star formation at high redshift by M. Cano-Diaz, R. Maiolino, A. Marconi, H. Netzer, O. Shemmer, and G. Cresci, A&A 537, L8 Quasar feedback is frequently invoked to help explain how star formation is moderated, in particular at high redshift. However, evidence of this phenomenon is scarce. The authors have used the VLT-SINFONI spectroscopy of a luminous quasar at z=2.4 and find [OIII] emission that reveals a massive outflow and narrow Halpha emission revealing star formation. The Halpha emission is strongly suppressed in the [OIII] region, indicating that the quasar outflow has quenched the star formation, by removing the molecular gas.   Magnetic flux emergence: a precursor of solar plasma expulsion (Archontis & Hood) Monday, 02 January 2012 08:00 Vol. 537 In section 9. The Sun Magnetic flux emergence: a precursor of solar plasma expulsion by V. Archontis and A.W. Hood, A&A 537, A62 The emergence of magnetic flux through the stellar surface is a key to understanding the observable consequences of stellar activity on the surface and in the corona. The authors present a three-dimensional magneto-hydrodynamics models of this emergence process from the top of the convection zone into the lower corona. They find that the interaction of the emerging flux with the pre-existing field is crucial for the evolution of the eruption. For configurations favoring reconnection, ejective eruptions are found, while the emerging flux tube remains confined for other configurations.   Chemical differentiation toward the Pipe nebula starless cores (Frau et al.) Wednesday, 18 January 2012 08:00 Vol. 537 In section 1. Letters Chemical differentiation toward the Pipe nebula starless cores by P. Frau, J. M. Girart, and M. T. Beltran, A&A 537, L9 Thanks to the new IRAM-30m wide FTS backend, the authors have been able to make a wide line survey at 3 mm toward the young diffuse starless cores of the Pipe nebula. They find a wide variety of abundances and chemistry and propose a new classification of cores based on the strength of their line emission. This classification led them to identify the so-called "Core 47" as a possible failed core, since it is rich in sulfur oxides, indicating it was quite dense recently and has been blown out to a diffuse core now.   Structures in debris discs ( P. Thébault) Friday, 06 January 2012 08:00 Vol. 537 In section 15. Numerical methods and codes A new code to study structures in collisionally active, perturbed debris discs: application to binaries by P. Thébault, A&A 537, A65 The author presents a new set of algorithms for studying the collisionally dominated steady state structure of debris disks in two dimensions forced by an eccentrically orbiting companion. The effects of Poynting-Robertson drag, particle destruction, and rebunching of the fragments are all included explicitly. The model also computes the parameters necessary for producing images of such disks.   The specific frequencies of ultra-compact dwarf galaxies (Mieske et al.) Monday, 19 December 2011 08:00 Vol. 537 In section 4. Extragalactic astronomy The specific frequencies of ultra-compact dwarf galaxies byS. Mieske, M. Hilker, and I. Misgeld, A&A 537, A3 A&A press release: Astronomy & Astrophysics is publishing a new statistical study of the so-called 'ultra-compact dwarf galaxies' (UCDs), which are still mysterious objects. A team of astronomers has investigated how many of these UCDs exist in nearby galaxy clusters and groups. They show that the properties of UCDs match those of bright star clusters. Read the A&A press release