Recent HST and ISO observations provide very severe limits on any compact baryonic contributions to galactic (dark) halos. When combined with Milky Way Galaxy microlensing results, almost the entire plausible range of massive compact baryonic objects is excluded by direct observation. Deep direct imaging at 7μm and 15μm with ISOCAM on the ISO spacecraft directly exclude hydrogen-burning stars o...

ABSTRACT We consider the possibility that Milky Way’s dark matter halo possesses a non-vanishing equation of state. Consequently, we evaluate contribution due to speed sound, assuming content galaxy behaves like fluid with pressure. In particular, model distribution via an exponential sphere profile in galactic core, and inner parts whereas compare three widely used profiles for halo, i.e. Eina...

In a recent letter [1] with the same title, Farrar and Piran offered an explanation for the near isotropy of the arrival directions [2] of ultrahigh energy cosmic rays (UHECRs) and the apparent absence [3] of the so called ‘GZK cutoff’ in their spectrum around 10 eV due to pion photoproduction on the cosmic background radiation (CMB) that was predicted independently by Greisen [4] and by Zatsep...

Using the near infrared fluxes of local galaxies derived from Cosmic Background Explorer (COBE)/Diffuse Infrared Background Experiment (DIRBE) J(1.25 μm) K (2.2 μm) & L (3.5 μm) band maps and published Cepheid distances, we construct Tully-Fisher diagrams for the nearby galaxies. The measured dispersions in these luminosity-linewidth diagrams are remarkably small: σJ = 0.09 magnitudes, σK = 0.1...

We present results for the chemical evolution of the Milky Way including predictions for elements from Deuterium to Europium. A comparison with the most accurate and recent data allows us to draw important conclusions on stellar nucleosynthesis processes as well as on mechanisms of galaxy formation.

Understanding the Milky Way structure and evolution is a major objective in astrophysics. Our Galaxy is an object of highest interest for learning about galaxy formation and evolution in general. Many data of different kinds (photometry, astrometry, spectroscopy) are available for millions of stars in the Milky Way, which interpretation in terms of evolution is not easy. Stars in the Milky Way ...