Related papers: Ring Nebulae: Tracers of the CNO Nucleosynthesis

We present deep spectra of ring nebulae associated with Wolf-Rayet (WR) and O-type stars: NGC 6888, G2.4+1.4, RCW 58, S 308, NGC 7635 and RCW 52. The data have been taken with the 10m Gran Telescopio Canarias and the 6.5m Clay Telescope. We…

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 present new observations of O II recombination lines in ten bright planetary nebulae, along with spatially-resolved measurements of O II and [O III] in the Ring nebula NGC 6720, to study the discrepancy between abundances derived from O…

The composite galaxy NGC 4102 hosts a LINER nucleus and a starburst. We mapped NGC 4102 in the 12.8 micron line of [NeII], using the echelon spectrometer TEXES on the NASA IRTF, to obtain a data cube with 1.5" spatial and 25 km/s spectral,…

This work aims to search for the observational footprints of the interactions between the interstellar medium (ISM) and stellar winds in the Wolf-Rayet (WR) nebula NGC6888 in order to understand its ionization structure, chemical…

We present deep spectroscopy of three Galactic planetary nebulae (PNe) with large abundance discrepancy factors (ADFs): NGC6153, M1-42 and Hf2-2. The spectra were obtained with VLT/UVES and cover the whole optical range (3040-11,000 A) with…

This paper is the third in a series reporting on a study of carbon abundances in a carefully chosen sample of planetary nebulae representing a large range in progenitor mass and metallicity. We make use of the IUE Final Archive database…

We have obtained new velocity-resolved spectra of the [CII] 158 micron line towards the Ring Nebula in Lyra (NGC 6720), one of the best-studied planetary nebulae, in order to probe its controversial 3-dimensional structure and to estimate…

We present [Fe/H], ages, and Ca abundances for an initial sample of 10 globular clusters in NGC 5128 obtained from high resolution, high signal-to-noise ratio echelle spectra of their integrated light. All abundances and ages are obtained…

Low dispersion spectra have been obtained of five planetary nebulae in the elliptical galaxy NGC 5128 (Centaurus-A) from the catalogue of Hui et al. (1993). The planetary nebulae (PN) cover a range of galactocentric radius from 7.9 to 17.7…

Multiple populations revealed in globular clusters (GCs) are important windows to the formation and evolution of these stellar systems. The metal-rich GCs in the Galactic bulge are an indispensable part of this picture, but the high optical…

We present new optical spectra of the nearby, bright, planetary nebula NGC 6778. The nebula has been known to emit strong recombination lines for more than 40 years but this is the first detailed study of its abundances. Heavy element…

We present first results of near-infrared integral field spectroscopy of the central 8''$\times$8'' of the Wolf-Rayet nucleus of the barred spiral galaxy NGC 6764. In addition to stellar CO and Na I absorption lines as well as recombination…

We have obtained spectroscopic observations of the nebulae around seven Wolf-Rayet (WR) stars, four in the Milky Way (WR 8, 16, 18 and 40) and three in the LMC (BAT99-2, -11 and -38). They were observed using the ESO NTT with the EFOSC-2…

We present Submillimeter Array (SMA) mapping of $^{12}$CO $J=2\rightarrow 1$, $^{13}$CO $J=2\rightarrow 1$, and CN $N=2\rightarrow 1$ emission from the Ring-like planetary nebula (PN) NGC 3132, one of the subjects of JWST Early Release…

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 have observed with the 30-m IRAM telescope, the CSO telescope and the ISOsatellite (Infrared Space Observatory) the rotational lines of CO at millimeter, submillimeter and far infrared wavelengths in the direction of C-rich stellar…

We discuss images of the central ~10 kpc (in projection) of the galaxy merger NGC 6240 at H and K' bands, taken with the NIRC2 narrow camera on Keck II using natural guide star adaptive optics. We detect 28 star clusters in the NIRC2…

NGC 6441 is a bulge globular cluster with an unusual horizontal branch morphology and a rich population of RR Lyrae (RRL) and Type II Cepheid (T2C) variables that is unexpected for its relatively high metallicity. We present near-infrared…

A number of planetary nebulae show binary central stars and significant abundance discrepancies between values estimated from colisionally excited lines when compared to the same abundances estimated from recombination lines. One approach…