The main aim of this paper is to report two new detections of tidal debris in the northern stream of the Sagittarius dwarf galaxy located at 45° and 55° from the center of the galaxy. Our observational approach is based on deep color-magnitude diagrams that provide accurate distances, surface brightness, and the properties of stellar population of

The variation of the mass-to-light M/L ratios of early-type galaxies as a function of their luminosities L is investigated. It is shown that the tilt β=0.27 (in the B band) of the fundamental plane relation M/L~Lβ can be understood as a combination of two effects: about one-quarter (i.e., Δβ=0.07) is a result of systematic variations of the stellar

In this paper we discuss the reason why the parameters of the Sérsic model best-fitting the major axis light profile of elliptical galaxies can differ significantly from those derived for the minor axis profile. We show that this discrepancy is a natural consequence of the fact that the isophote eccentricity varies with the radius of the isophote

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