Related papers: Coronal abundances from high-resolution X-ray data…
High-resolution X-ray spectroscopy has advanced our understanding of the hot Universe by revealing physical properties like kinematics, temperature, and abundances of the astrophysical plasmas. Despite the technical and scientific…
The damped Lyman alpha systems seen in the spectra of high redshift QSOs offer the means to determine element abundances in galaxies observed while still at an early stage of evolution. Such measurements, which have only recently come…
We report a detailed analysis of the coronal abundance of 4 stars with varying levels of activity and with accurately known photospheric abundances. The coronal abundance is determined here using a line flux analysis and a full…
The spectra of the planetary nebula NGC2392 is reanalysed using spectral measurements made in the mid-infrared with the Spitzer Space Telescope. The aim is to determine the chemical composition of this object. We also make use of IUE and…
Upcoming facilities such as the Herschel Space Observatory or ALMA will deliver a wealth of molecular line observations of young stellar objects (YSOs). Based on line fluxes, chemical abundances can then be estimated by radiative transfer…
We use ultraviolet spectra of Capella from the Hubble Space Telescope (HST) and Far Ultraviolet Spectroscopic Explorer (FUSE) satellites to study interstellar absorption lines from the Local Interstellar Cloud (LIC). Measurements of these…
We analyze the X-ray properties for a sample of 23 high probability AGN candidates with ultraviolet variability identified in Wasleske et al. (2022). Using data from the Chandra X-ray Observatory and the XMM-Newton Observatory, we find…
Using a sample of 70 924 stars from the second data release of the GALAH optical spectroscopic survey, we construct median sequences of [X/Mg] vs. [Mg/H] for 21 elements, separating the high-$\alpha$/``low-Ia'' and low-$\alpha$/``high-Ia''…
Accurate determination of stellar atmospheric parameters and elemental abundances is crucial for Galactic archeology via large-scale spectroscopic surveys. In this paper, we estimate stellar atmospheric parameters -- effective temperature…
We undertake a spectral study of a sample of bright X-ray sources taken from six XMM-Newton fields at high galactic latitudes, where AGN are the most populous class. These six fields were chosen such that the observation had an exposure…
We present follow-up spectra of 39 emission-line galaxies (ELGs) from the KPNO International Spectroscopic Survey (KISS). Many targets were selected as potentially low metallicity systems based on their absolute B magnitudes and the…
We analyze HST spectra and Chandra observations of a sample of 21 LINERs, at least 18 of which genuine AGN. We find a correlation between the X-rays and emission lines luminosities, extending over three orders of magnitude and with a…
For the first time, neon abundance has been derived in the narrow line region from a sample of Seyfert~2 nuclei. In view of this, we compiled from the literature fluxes of optical and infrared (IR) narrow emission lines for 35 Seyfert 2…
We have obtained spectroscopic observations from 3600 Angstrom to 9200 Angstrom with FORS at the Very Large Telescope for approximately 70 H II regions located in the spiral galaxies NGC 1232, NGC 1365, NGC 2903, NGC 2997 and NGC 5236.…
Hard X-ray selection is the most efficient way to discriminate between accretion-powered sources, such as AGN, from sources dominated by starlight. Hard X-rays are also less affected than other bands by obscuration. We have then carried out…
We report on an on-going analysis of high-resolution UV spectra of hot hydrogen-rich central stars of planetary nebulae (CSPN), obtained with the Hubble Space Telescope and FUSE. Since UV spectra of many CSPN are dominated by Fe and Ni…
We exploit XMM-Newton archival data in a study of the extended X-ray emission emanating from the Galactic Centre (GC) region. EPIC-pn and EPIC-MOS observations, with a total exposure approaching 0.5 and 1 Ms respectively, were used to…
We present the previously unanalysed high quality XMM-Newton spectrum of an ultraluminous X-ray source candidate in NGC 4517. As with other high quality ULX spectra, a downturn in the spectrum is observed at ~6 keV. Both of the recent disc…
High quality X-ray spectra of NGC 4636 are obtained with ASCA. Theoretical models are found unable to reproduce the data in the Fe-L line region. Spectral data above 1.4 keV indicate that Mg to Si abundance ratio is $\sim 1$ solar. Assuming…
We briefly review and extend our discussion of the ROSAT detection of the extraordinarily luminous (>10^{42} erg/s) partly extended (> 30 kpc diameter) X-ray emission from the double-nucleus ultraluminous infrared galaxy NGC 6240. The ROSAT…