We revise the explanation for the ``expanding H II regions ring'' of NGC 4736. From the analysis of long-slit spectra, we identify structures within the emission region previously reported in the literature as a single ring (former parameters: R~47", FWHM=21"). The H II ring is located at 35" (1.12 kpc) galactocentric distance, and its thickness is

We discuss the selection and observations of a large sample of nearby galaxies, which we are using to quantify the star formation activity in the local Universe. The sample consists of 334 galaxies across all Hubble types from S0/a to Im and with recession velocities of between 0 and 3000 km s-1. The basic data for each galaxy are narrow band

Since 1998 the Earthshine Project has been a collaborative effort between Big Bear Solar Observatory/New Jersey Institute of Technology and California Institute of Technology. Cyclic spectroscopic observations of the dark and bright sides of the moon (or earthshine and moonshine, respectively) have been carried out in the visible region at Palomar

The Earthshine Project is a collaborative effort between Big Bear Solar Observatory (New Jersey Institute of Technology) and the California Institute of Technology. Our primary goal is the precise determination of a global and absolutely calibrated albedo of the Earth and the characterization of its synoptic, seasonal and inter-annual variability

We report on an analysis of high resolution Chandra spectra of two stars with very similar spectral types and rotation rates but with very different evolutionary histories. AB Doradus is a young relatively bright (V=6.9) rapidly rotating (P=0.51d) late-type star (dK0-2) that is just evolving onto the main sequence. V471 Tau is a post-common

The regular pattern that high n p-mode frequencies of solar-like stars show is used to design a method for a quick check to the identification of the modes. The case of a wrong mode identification or a spurious one is clearly shown by the method, which depends rather weakly on the possible stellar models. An application of the method shows