It has recently been shown that the correct halo mass function high-mass behavior may be obtained by an appropriate treatment of the all-mass-at-center problem. Here we show that the treatment of this problem leads to an accumulated mass fraction, F, that is not a universal function of the linear variance of the density contrast but depends on the

We present a preliminary analysis of penumbral spectra observed with unprecedented angular resolution (0.2 arcsec) using the new Swedish 1-m Solar Telescope. The use of a non-magnetic line allows us to measure Doppler shifts without magnetic contamination. The observed Doppler shifts depend on the part of the line used for measuring, indicating

We reviewed the polarization properties of hydrogen lines in the presence of electric and magnetic fields. We first considered the case of completely depolarized hydrogen atoms. Under this assumption, the hydrogen lines manifest complex polarization signatures due to the combined Stark and Zeeman effect tep{c0 CL93}. One can derive convenient

The potential discovery of Earth-like planets around other stars will need, apart from a sophisticated technological development, the design of techniques for identifying the most representative parameters of their atmospheres and surfaces. The search for life will constitutes the holy grail of this search. However, for many decades the

We present the results of a program to derive the complete star-formation history of the Local Group dwarf irregular galaxy Leo A (DDO 69). Leo A is a low-luminosity (Mv = -11.7), very gas-rich (M(HI)/LB = 1.6) galaxy. Our analysis is based on color-magnitude diagrams derived from deep HST/ACS imaging; the CMDs reach well below the oldest main

The peculiar variable star V838 Mon underwent an extremely unusual outburst in early 2002. Unlike a classical nova, V838 Mon has remained very cool throughout its outburst. It is illuminating the most spectacular light echo in astronomical history, which is being imaged regularly with the Hubble Space Telescope (HST) as well as from the ground. In