Related papers: A cold component and the complex velocity structur…

We use high signal-to-noise ratio, high-resolution VLT-UVES data of Q J0643-5041 amounting to a total of more than 23 hours exposure time and fit the neutral hydrogen, metals and H2 absorption features with multiple-component Voigt…

We present a study of cold gas absorption from a damped Lyman-$\alpha$ absorber (DLA) at redshift $z_{\rm abs}=1.946$ towards two lensed images of the quasar J144254.78+405535.5 at redshift $z_{\rm QSO} = 2.590$. The physical separation of…

We report the discovery of two low redshift HI 21cm absorbers, one at z = 0.2212 towards the z_{em} = 0.630 quasar OI 363 (B0738+313), and the other at z = 0.3127 towards PKS B1127-145 (z_{em} = 1.187). Both were found during a survey of…

An independent analysis of the molecular hydrogen absorption system at z = 2.059 in the spectrum of the quasar J2123-0050 is presented. The H_2 system consists of two components (A and B) with column densities log N^A(H_2) = 17.94+/-0.01…

We investigate the practice of assigning high spin temperatures to damped Lyman-alpha absorption systems (DLAs) not detected in HI 21-cm absorption. In particular, Kanekar & Chengaulr (2003) have attributed the mix of 21-cm detections and…

We probe the physical conditions in high redshift galaxies, specifically, the Damped Lyman-alpha Systems (DLAs) using neutral carbon (CI) fine structure lines and molecular hydrogen (H2). We report five new detections of CI and analyze the…

In order to interpret H2 (molecular hydrogen) quasar absorption line observations of damped Ly-alpha systems (DLAs) and sub-DLAs, we model their H2 abundance as a function of dust-to-gas ratio, including H2 self-shielding and dust…

With IRAM-30m/HERA, we have detected CO(2-1) gas complexes within 30 arcsec (~100 pc) from the center of M31 amounting to a minimum total mass of 4.2 x 10^4 Msol (one third of the positions are detected). Averaging the whole HERA field, we…

Damped Lyman-$\alpha$ absorbers (DLAs) with molecular hydrogen have been probed in detail through both spectroscopic observations and numerical modelling. However, such H$_2$ absorbers are quite sparse at very high redshifts. We identify…

We present a detailed analysis of chemical abundances in a sub-damped Ly alpha absorber (sub-DLA) at z=2.187 towards the quasar HE0001-2340 (z_em=2.28) using VLT/UVES data. This sub-DLA system consists of at least 25 individual…

We present the results of three separate searches for HI 21-cm absorption in a total of twelve damped Lyman-alpha absorption systems (DLAs) and sub-DLAs over the redshift range z = 0.86-3.37. We find no absorption in the five systems for…

Spectra obtained with the Hubble Space Telescope GHRS are combined with high-resolution optical spectra and UV spectra from Copernicus to study the abundances and physical conditions in the diffuse interstellar clouds seen along the line of…

STIS Echelle observations at a resolution of 10 km/s and UVES/VLT spectroscopy at a resolution of 7 km/s of the luminous QSO HE 0515-4414 (z_em = 1.73, B = 15.0) reveal four intervening O VI absorption systems in the redshift range 1.2 <…

We present the detection of CII and CII* absorption in the z = 3.0543 damped Ly-alpha system toward Q0000-2619. The derived population ratio implies a fine structure excitation temperature between 19.6 and 21.6 K. The upper value sets a…

We present the results of a series of imaging and spectroscopic observations aimed at identifying and studying the galaxy responsible for the z = 3.38639 damped lya system in the z = 3.61 QSO Q0201+1120. We find that the DLA is part of a…

We present HST/COS observations of highly ionized absorption lines associated with a radio-loud QSO at $z=1.1319$. The absorption system has multiple velocity components, tracing gas that is largely outflowing from the QSO at velocities of…

We study the physical properties and molecular excitation of the different warm gas components found in the protoplanetary nebula CRL 618. We revise our previous Herschel/HIFI observations, which consist of several 12CO and 13CO lines in…

We combine UV spectra obtained with the HST/GHRS echelle, IMAPS, and Copernicus to study the abundances and physical conditions in the predominantly ionized gas seen at high (-105 to -65 km/s) and intermediate velocities (-60 to -10 km/s)…

We report the serendipitous detection of an H$_{2}$-bearing damped Lyman-$\alpha$ absorber at z = 0.576 in the spectrum of the QSO J0111-0316 in the Cosmic Ultraviolet Baryon Survey. Spectroscopic observations from HST-COS in the…

We present an analysis of XMM-Newton spectra of the low-redshift quasar IRAS 13349+2438. The RGS spectrum shows a large number of absorption lines from two zones of warm absorption, with velocities of $\sim$-600 km s$^{-1}$, as noted by…