The discovery in the COBE all-sky maps of a bright isotropic background in the far-IR/sub-mm, of likely extragalactic origin (CIRB), with a proeminent hump at a wavelength of 140 μm, has been interpreted at first as the integrated emission by dust present in very distant galaxies (Puget et al. 1996; Hauser et al. 1998). What is the relation between

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In a typical young open cluster the polarimetric data shows, for normal stars, that the distribution of angles of the polarization vectors can be describe by a fixed value that caracterizes the cluster. Individual stars show some scatter over this mean angle because of fluctuations in the interstellar medium (ISM), variations in the magnetic field

The Hubble classification scheme of galaxies is based on blue-light appearance. Atlases reveal the rich variety of responses of the Population I component (the "mask") of gas and dust to the underlying, older, stellar population. However, the Population I component may only constitute 5 percent of the dynamical mass of the galaxy; furthermore

Oxygen abundances have been derived in a sample of very metal-poor stars using the O I triplet at λλ7771-5 Å and OH lines in the near UV. A detailed NLTE analysis of iron lines has been carried out for one of the observed stars, BD +23°3130, providing consistent values of effective temperature and surface gravity that are in very good agreement