Related papers: WR bubbles and HeII emission
In 1997 and 2008 we used the WFPC2 camera on board of the Hubble Space Telescope to obtain two sets of narrow-band H$\alpha$ images of the runaway Wolf-Rayet (WR) star WR 124 surrounded by its nebula M1-67. This two-epoch imaging provides…
We present a morphological study of nebulae around Wolf-Rayet (WR) stars using archival narrow-band optical and Wide-field Infrared Survey Explorer (WISE) infrared images. The comparison among WISE images in different bands and optical…
We use WR124 (WN8h) and its associated nebula M1-67, to test theoretical non-LTE models for Wolf-Rayet (WR) stars. Lyman continuum ionizing flux distributions derived from a stellar analysis of WR124, are compared with nebular properties…
We present new results on the chemical composition of the Galactic ring nebula NGC6888 surrounding the WN6(h) star WR136. The data are based on deep spectroscopical observations taken with the High Dispersion Spectrograph at the 8.2m Subaru…
We report the detection of near-IR H$_2$ emission from the low-ionization structures (knots) in two planetary nebulae. The deepest ever, high-angular resolution H$_2$ 1-0 S(1) at 2.122$\mu$, H$_2$ 2-1 S(1) at 2.248$\mu$ and Br$\gamma$…
Recent observations reveal that the central star of the planetary nebula Abell 48 exhibits spectral features similar to massive nitrogen-sequence Wolf-Rayet stars. This raises a pertinent question, whether it is still a planetary nebula or…
We discuss our most recent findings on the diffuse X-ray emission from Wolf-Rayet (WR) nebulae. The best-quality X-ray observations of these objects are those performed by XMM-Newton and Chandra towards S308, NGC2359, and NGC6888. Even…
The Small Magellanic Cloud (SMC) is the nearest low-metallicity dwarf galaxy. Its proximity and low reddening has enabled us to detect its Wolf-Rayet (WR) star population with 12 known objects. Quantitative spectroscopy of the stars…
Deep optical spectra of the high excitation planetary nebula NGC 1501 and its W04 central star are presented. A recombination line abundance analysis of the central star's emission-line spectrum yields He:C:O mass fractions of…
We performed Herschel/HIFI observations of intermediate-excitation molecular lines in the far-infrared/submillimeter range in a sample of ten protoplanetary nebulae and young planetary nebulae. The high spectral resolution provided by HIFI…
We report the discovery of [NeV]3426 emission, in addition to HeII4686 emission, in six compact star-forming galaxies. These observations considerably increase the sample of eight such galaxies discovered earlier by our group. For four of…
Dynamical studies of superbubbles and Wolf-Rayet ring nebulae show discrepancies from the standard, adiabatic model for wind-blown bubbles. We therefore study the physical properties and kinematics of three candidate bubbles blown by single…
We present results obtained towards the HII regions N159, N166, and N132 from the emission of several molecular lines in the 345 GHz window. Using ASTE we mapped a 2.4' $\times$ 2.4' region towards the molecular cloud N159-W in the…
For three nebulae that have early-WN Wolf-Rayet exciting stars, NGC 6888, WR 8 and Abell 48, we have obtained Herschel-PACS line scans of the [N III] 57 um and [O III] 88 micron lines, along with the 122 and 205 micron lines of [N II]. From…
We present narrow-band near-infrared images of a sample of 11 Galactic planetary nebulae (PNe) obtained in the molecular hydrogen (H$_{2}$) 2.122 $\mu$m and Br$\gamma$ 2.166 $\mu$m emission lines and the $K_{\rm c}$ 2.218 $\mu$m continuum.…
We use line-of-sight velocity information on the filamentary emission-line nebula of NGC 1275 to infer a dynamical model of the nebula's flow through the surrounding intracluster gas. We detect outflowing gas and flow patterns that match…
We present spectroscopy of three hydrogen-deficient central stars of faint planetary nebulae, with effective temperatures ($T_\mathrm{eff}$) in excess of 100,000 K. The nucleus of RaMul 2 is a Population II Wolf-Rayet star of spectral type…
We present mid-infrared ISO-SWS observations of the fine-structure emissions lines [NeII]12.8, [NeIII]15.6, [NeIII]36, [ArII]6.9, [ArIII]8.9, [SIII]18.7, [SIII]33.5, [SIV]10.5, and the recombination lines Br_alpha and Br_beta, in a sample…
The close correlation between cooling flows and emission-line nebulae in clusters of galaxies has been recognized for over a decade and a half, but the physical reason for this connection remains unclear. Here we present deep optical…
We analyze Chandra observations of the Wolf-Rayet (WR) bubble NGC 6888. This WR bubble presents similar spectral and morphological X-ray characteristics to those of S 308, the only other WR bubble also showing X-ray emission. The observed…