We compute the z = 3 neutral hydrogen column density distribution function f(NHI) for 19 simulations drawn from the Overwhelmingly Large Simulations project using a post-processing correction for self-shielding calculated with full radiative transfer of the ionizing background radiation. We investigate how different physical processes and

The spectral line polarization produced by optically pumped atoms contains a wealth of information on the thermal and magnetic structure of a variety of astrophysical plasmas, including that of the solar atmosphere. A correct decoding of such information from the observed Stokes profiles requires a clear understanding of the effects that

It is not yet known if the properties of molecular gas in distant protocluster galaxies are significantly affected by their environment as galaxies are in local clusters. Through a deep, 64 h of effective on-source integration with the Australian Telescope Compact Array (ATCA), we discovered a massive, Mmol = 2.0 ± 0.2× 1011 M⊙, extended, 40 kpc

We present a new determination of the interstellar 12CH+/13CH+ ratio in the solar neighbourhood, based on high spectral resolution CCD observations of the CH+ molecule in the direction of the star HD 26676 (d ≃ 150 pc). The measured absorption at λ4233 Å is one of the most intense 12CH+ lines detected so far (Wλ =23.5 mÅ), and is produced in the

We present the results of the study of visible (BVRI) intra-night variability of the BL Lac object OJ287. The observations were carried out on a total of 29 nights during the period November 1993-October 1994, with only nights with at least 4 observations being included. Three telescopes were used for the study: the 1m Jacobus Kapteyn Telescope and

We present a census of variable stars in six M31 dwarf spheroidal satellites observed with the Hubble Space Telescope. We detect 870 RR Lyrae (RRL) stars in the fields of And I (296), II (251), III (111), XV (117), XVI (8), and XXVIII (87). We also detect a total of 15 Anomalous Cepheids, three eclipsing binaries, and seven field RRL stars