Related papers: Pumping up the [N I] nebular lines
The shape of the ionising spectra of galaxies is a key ingredient to reveal their physical properties and to our understanding of the ionising background radiation. A long-standing unsolved problem is the presence of HeII nebular emission…
The presence of O VI ions can be indicative of plasma temperatures of a few times 10^5 K that is expected in heat conduction layers between the hot shocked stellar wind gas at several 10^6 K and the cooler (~10,000 K) nebular gas of…
We present CI 3P1-3P0 spectra at four spiral arm positions and the nuclei of the nearby galaxies M83 and M51 obtained at the JCMT. This data is complemented with maps of CO 1-0, 2-1, and 3-2, and ISO/LWS far-infrared data of CII (158…
We present spectrophotometry of 12 Galactic and 3 Magellanic Cloud planetary nebulae (PNe). Nine of the Galactic PNe were observed by scanning the slit across the PN. We use the fluxes of collisionally excited lines (CELs) to derive…
We report detailed analyses of deep, high-resolution spectra of three Galactic planetary nebulae (PNe) with high abundance discrepancy factors (ADFs), Hf2-2, M1-42 and NGC6153, obtained with the Ultraviolet and Visual Echelle Spectrograph…
Tomographic and 3-D analyses for extended, emission-line objects are applied to long-slit ESO NTT + EMMI high-resolution spectra of the intriguing planetary nebula NGC 7009, covered at twelve position angles. We derive the gas expansion…
In order to study the nature, origin, and impact of turbulent velocity fluctuations in the ionized gas of the Orion Nebula, we apply a variety of statistical techniques to observed velocity cubes. The cubes are derived from high resolving…
Far Ultraviolet radiation has been recognized as the main source of heating of the neutral interstellar gas, and, as a consequence, it determines whether the thermal balance of the neutral gas results in cold ($T\sim 50 - 100 K$) clouds…
After briefly reviewing the impact of various parameters on photoionization models, we illustrate the importance of the nebular geometry by two examples: we first compare the results from models with thin shell and full shell geometry, and…
We present the general properties of the far-ultraviolet (FUV; 1370-1720A) continuum background over most of the sky, obtained with the Spectroscopy of Plasma Evolution from Astrophysical Radiation instrument (SPEAR, also known as FIMS),…
We present HI 21cm observations of the Orion Nebula, obtained with the Karl G. Jansky Very Large Array, at an angular resolution of 7.2"x5.7" and a velocity resolution of 0.77 km/s. Our data reveal HI absorption towards the radio continuum…
Far-ultraviolet (FUV) radiation is a driving source of photochemistry in planetary atmospheres. Proper interpretation of atmospheric observations requires a full understanding of the radiation environment that a planet is exposed to. Using…
The narrow line region of active galaxies is formed by gas clouds surrounded by a diluted gas. Standard one-dimensional photoionization models are usually used to model this region in order to reproduce the observed emission lines. Since…
Stellar and nebular abundance indicators reveal that there exists significant abundance fluctuations in the interstellar medium (ISM) of gas-rich galaxies. It is shown that at the present observed solar level of O/H $\sim 6 \times 10^{-4}$,…
(abridged) Non-ionizing stellar continua are a source of photons for continuum pumping in the hydrogen Lyman transitions. In the environments where these transitions are optically thick, deexcitation occurs through higher series lines, so…
The [CII] $158\,\mu\mathrm{m}$ fine-structure line is one of the dominant coolants of the neutral interstellar medium. It is hence one of the brightest far-infrared emission lines and can be observed not only in star-forming regions…
By combining optical and near-IR observations from the Hubble Space Telescope with NIR photometry from the Spitzer Space Telescope it is possible to measure the rest-frame UV-optical colours of galaxies at z=4-8. The UV-optical spectral…
Using a suite of radiation hydrodynamic simulations of star cluster formation in turbulent clouds, we study the escape fraction of ionizing (Lyman continuum) and non-ionizing (FUV) radiation for a wide range of cloud masses and sizes. The…
We used high-resolution [C II] 158 $\mu$m mapping of two nebulae IC 59 and IC 63 from SOFIA/upGREAT in conjunction with ancillary data on the gas, dust, and polarization to probe the kinematics, structure, and magnetic properties of their…
I report on the high resolution spectra of the remarkable X9 solar flare of 2024 Oct 03 (SOL2024-10-03T12:08) and evaluate the extent to which nonthermal electron beams that generate dense chromospheric condensations can power very bright…