Primitive asteroids contain the most pristine material that gave birth to the rocky planets. Interest in spectral data from primitive asteroids that could be the source of the primitive near-Earth asteroids (NEAs) has increased in anticipation of the two sample-return missions that will reach their targets in the next four years and bring samples

We present a detailed study of the faint Milky Way satellite Draco II (Dra II) from deep CFHT/MegaCam broad-band g and i photometry and narrow-band metallicity-sensitive CaHK observations, along with follow-up Keck II/DEIMOS multi-object spectroscopy. Forward modelling of the deep photometry allows us to refine the structural and photometric

We develop a method for computing the probability densities of spherical voids in distribution of galaxies on a large scale. This method is applied to Poissonian cluster models. We consider CDM biased and non-biased models; the appropriate approximation has been used in each case. We find that, in the latter case, the probability finding a void

Context. We present a spectral analysis of the binary G 224-58 AB, which consists of the coolest M extreme subdwarf (esdM5.5) and a brighter primary (esdK5). This binary may serve as a benchmark for metallicity measurement calibrations and as a test bed for atmospheric and evolutionary models for esdM objects. Aims: We perform the analysis of

The observed emission-line ratios of the extended emission-line regions of Cen A and 3C 227 are compared with the theoretical results from photoionization models, assuming a power-law spectrum for the nuclear ionizing radiation. We show that a variation of the optical depth of the emitting gas can mimic a variation of the ionization parameter. Most

We analyze the timing of photons observed by the MAGIC telescope during a flare of the active galactic nucleus Mkn 501 for a possible correlation with energy, as suggested by some models of quantum gravity (QG), which predict a vacuum refractive index ≃1+E, n=1,2. Parametrizing the delay between γ-rays of different energies as Δt=±τE or Δt=±τE, we