We investigate the assembly histories 56 of galaxy clusters using a pair of cosmological LCDM N-body simulations. We track infalling galaxy subhalos with masses large enough to host 0.1 L* galaxies , and find that the majority of cluster member galaxies experienced no ``pre-processing'' in the group environment prior to their accretion into the

The diffraction-limited observations of the Hinode Spectro-Polarimeter have open exciting possibilities for the analysis of the weak magnetic signals of the solar internetwork (IN). Hinode/SP has demonstrated that the IN is permeated by highly inclined fields with weak flux densities. These observations are important to solve the discrepancy

Aims: We study the observational signature of flux emergence in the photosphere using synthetic data from a 3D MHD simulation of the emergence of a twisted flux tube. Methods: Several stages in the emergence process are considered. At every stage we compute synthetic Stokes spectra of the two iron lines Fe I 6301.5 Å and Fe I 6302.5 Å and degrade

A step in the analysis of the data from the GOLF (Global Oscillations at Low Frequency) instrument on SOHO (SOlar and Heliospheric Observatory, an ESA/NASA Mission) involves the calculation of the sensitivity of the GOLF signal to the velocity at each point on the solar surface. A successful model of this sort will permit the intercomparison of

Simulations for PASS (Permanent All Sky Survey) are shown, which include the generation of artificial CCD images and photometric extraction of the stellar sources. First results indicate that PASS can obtain photometry with sufficient precision to pursue its principal goal, the detection of giant planet transits for all stars up to 11th mag.

We report on the results of a coordinated observation of Mrk 421 during outburst using data from XMM-Newton and ground-based TeV data from two Imaging Air Cherenkov Telescopes, the Whipple 10m telescope, based in Arizona, and the MAGIC telescope, based on La Palma in the Canary Islands. The coordinated effort between the two TeV groups allowed for