Related papers: E(B-V), N(H I) and N(H_2)
Peculiar dust extinction laws have been reported for some type Ia supernovae (SNe) with the parameter $R_V$ much lower than the average value for the Milky Way (MW) of 3.1. Using optical photopolarimetry of supernova (SN) host galaxies, a…
We have examined radial velocities and fluxes of ultraviolet emission lines at different epochs, deduced from archival IUE and GRHS/HST spectra. The line fluxes give electron densities and were in addition used to calculate emission…
We observed M51 at three frequencies, 1.4GHz (20cm), 4.9GHz (6cm) and 8.4GHz (3.6cm), with the VLA and the Effelsberg 100m telescope to obtain the highest quality radio continuum images of a nearby spiral galaxy. These radio data were…
We studied the radio properties of very young massive regions of star formation in HII galaxies, with the aim of detecting episodes of recent star formation in an early phase of evolution where the first supernovae start to appear. Our…
We observed the 3335 MHz (9cm) F=1-1 line of CH toward a sample of diffuse clouds occulting compact extragalactic mm-wave continuum sources, using the old NRAO 43m telescope. Because radiofrequency observations of CH really must be…
We present and discuss European VLBI Network UHF band spectral line observations, made to localise the redshifted 21cm HI absorption known to occur in the subgalactic sized compact steep spectrum galaxies 3C 49 and 3C 268.3. We have…
The cosmic microwave background absorption intensity in the 21 cm line of neutral hydrogen in the presence of additional power in the form of a "bump" in the spectrum of cosmological density perturbations is calculated. The main…
We report the discovery of three HI absorbers toward low-power radio active galactic nuclei (AGNs) in a pilot HI absorption survey with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Compared to past studies, FAST…
We present observational evidences that dust in the circumnuclear region of AGNs has different properties than in the Galactic diffuse interstellar medium. By comparing the reddening of optical and infrared broad lines and the X-ray…
We present the results of a z>2.9 survey for HI 21-cm and molecular absorption in the hosts of radio quasars using the GMRT and the Tidbinbilla 70-m telescope. Previously published searches, which are overwhelmingly at redshifts of z<1,…
We investigate the relation between the optical extinction ($A_V$) and the hydrogen column density ($N_H$) determined from X-ray observations of a large sample of Galactic sightlines toward 35 supernova remnants, 6 planetary nebulae, and 70…
We present results from a search for the HI 21-cm line in absorption towards 16 bright radio sources with the 6-antenna commissioning array of the Australian Square Kilometre Array Pathfinder (ASKAP). Our targets were selected from the 2-Jy…
We present optical spectra and emission-line ratios of 12 Narrow-Line Seyfert 1 (NLS1) galaxies that we observed to study the ionizing EUV continuum. A common feature in the EUV continuum of active galactic nuclei is the big blue bump…
We discuss the results of continued spectroscopic monitoring of the variable intermediate-velocity (IV) absorption at v = -38 km/s toward HD 219188. After reaching maxima in mid-2000, the column densities of both Na I and Ca II in that IV…
H\alpha\ equivalent widths and UBV magnitudes are calculated for Be star disk models that grow in size and/or density with time. We show that these simple models are consistent with the known Be star classes of positive and inverse…
We present results from our EVN and GMRT observations of the radio continuum and spectral line emission in IRAS 17526+3253, along with an analysis of its arcsecond-scale radio properties using archival VLA data. The EVN observations…
The star-forming reservoir in the distant Universe can be detected through HI 21-cm absorption arising from either cool gas associated with a radio source or from within a galaxy intervening the sight-line to the continuum source. In order…
The neutral hydrogen and the ionized helium absorption in the spectra of quasars are unique probes of structure in the early universe. We present Far-Ultraviolet Spectroscopic Explorer observations of the line of sight to the quasar…
We aim to compare variations in the full-UV dust extinction curve (912-3000 Angstrom), with the HI/H$_2$/total H content along diffuse Milky Way sightlines, to investigate possible connections between ISM conditions and dust properties. We…
We present VLT-UVES echelle spectra of the Lyman alpha emission and absorption in five radio galaxies at redshifts z=2.55-4.1. Together with data from our pilot study, we have a sample of 7 such systems with radio source sizes ~ 1-90 kpc…