The point spread function of a segmented aperture is seriously affected by the misalignment of the segments. Stringent requirements apply to position sensors and their calibration. The Active Phasing Experiment (APE) will be a technical instrument aimed at testing possible phasing techniques for a European Giant Optical Telescope (EGOT) in a

Barred galaxies represent more than 2/3 among disk galaxies. The evolution of barred galaxies is deeply influenced by the dynamics of the bar. Moreover, the evolution of the bar itself determines the morphology of the rest of the galaxy. In this work, and by means of numerical simulations, we will show the evolution of isolated barred galaxies from

We report the discovery of clear observational signs of past accretion/merger events in one of the Milky Way satellite galaxies, the Sextans dwarf spheroidal (dSph). These were uncovered in the spatial distribution, internal kinematics, and metallicity properties of Sextans stars using literature CTIO/DECam photometric and Magellan/MMFS

In this paper the approximate Lambda-Operator (ALO) developed by Olson, Auer and Buchler (OAB, 1986) is inspected from a more mathematical standpoint and compared to presently most commonly applied ALOs. For simple model calculations,it is shown that OAB's operator which contains no arbitrary parameter always works close to the optimum convergence

We stand on the threshold of a critical expansion of asteroseismology of Sun-like stars, the study of stellar interiors by observation and analysis of their global acoustic modes of oscillation. The Sun-like oscillations give a very rich spectrum allowing the internal structure and dynamics to be probed down into the stellar cores to very high

We have carried out a spectroscopic study of asteroid 65 Cybele in the 2 - 4 μm and 5 - 14 μm regions, using NASA's IRTF and Spitzer Space Telescope, respectively. We compare these spectra with those of Trojan asteroids and asteroid 24 Themis. Our target is the largest member of the Cybele population; these asteroids represent a transition group