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Article
A high-mass planetary nebula in a Galactic open cluster
Planetary nebulae are the ionized ejected envelopes surrounding the remnant cores of dying stars. Theory predicts that main-sequence stars of one to about eight solar masses may eventually form planetary nebul...
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Article
Author Correction: Reduction of the maximum mass-loss rate of OH/IR stars due to unnoticed binary interaction
In the version of this Letter originally published, the caption of Fig. 2 incorrectly said J = 3–2; it should have said J = 2–1. This has now been corrected.
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Article
Reduction of the maximum mass-loss rate of OH/IR stars due to unnoticed binary interaction
In 1981, the idea of a superwind that ends the life of cool giant stars was proposed1. Extreme oxygen-rich giants, OH/IR stars, develop superwinds with the highest mass-loss rates known so far, up to a few 10−4 s...
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Article
The mysterious age invariance of the planetary nebula luminosity function bright cut-off
Planetary nebulae mark the end of the active life of 90% of all stars. They trace the transition from a red giant to a degenerate white dwarf. Stellar models1,2 predicted that only stars above approximately twice...
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Chapter and Conference Paper
Molecules in the AGB Stars of Nearby Galaxies
We obtained infrared spectra of Asymptotic Giant Branch (AGB) stars in nearby galaxies, and measured the equivalent widths of HCN and C2H2 bands for the carbon-rich stars, and SiO abundances for the oxygen-rich s...
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Chapter and Conference Paper
Molecules in the AGB Stars of Nearby Galaxies
We obtained infrared spectra of Asymptotic Giant Branch (AGB) stars in nearby galaxies, and measured the equivalent widths of HCN and C2H2 bands for the carbon-rich stars, and SiO abundances for the oxygen-rich s...
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Chapter
The Extended Atmosphere and Evolution of the RV Tauri Star, R Scuti
We found molecular bands in absorption and in emission in the infrared spectra of the RV Tau stars, R Sct. This is a unique property among the RV Tau stars, but rather commonly seen in Mira variables. The peri...
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Chapter
Three Micron Spectra of Carbon Stars in the Large Magellanic Cloud
Infrared spectra of six carbon-rich stars were obtained with the Very Large Telescope (VLT). We found a metallicity dependence in the equivalent width of the molecular bands, and we discuss the causes of this
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Chapter and Conference Paper
Old Stars in Dwarf Irregular Galaxies: WLM and NGC3109
We present evidence for the existence of old stellar halos in the dwarf irregular galaxies WLM and NGC3109, located in the outskirts of the Local Group. These halos consist of metal-poor ([Fe/H] < -1) and old (t ...
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Chapter
Evolution and Mass Loss of AGB Stars in the Small Magellanic Cloud
To study the final stages of the evolution of stars in the range of 1–8M ⊙ we have started a project on AGB stars in the Small Magellanic Cloud (SMC). Based on the IRAS Faint Source Catalog we have ...
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Chapter
ISO Spectroscopy of AGB Stars in the Magellanic Clouds
The study of AGB stars in the Magellanic Clouds has an important advantage over the study of galactic objects because of the known distance to the sources. Unfortunately the sources are relatively faint, makin...
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Chapter and Conference Paper
The Planetary Nebulae in the Sagittarius Dwarf Galaxy
There are 9 dwarf spheroidal galaxies in the neighbourhood of the Galaxy. The last to be discovered is in Sagittarius (Ibata et al 1994), situated at a distance of 25 kpc and is interacting with the Galaxy. It...
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Article
Evolution and Mass Loss of AGB Stars in the Small Magellanic Cloud
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Article
ISO Spectroscopy of AGB Stars in the Magellanic Clouds
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Chapter and Conference Paper
Imaging the Surfaces of Late-Type Stars
We discuss the prospects for resolving the disks of red-giants and Mira variables with the VLT and the VLTI. We also describe infrared aperture-masking observations with the NTT, from which we have measured an...
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Chapter and Conference Paper
The Asymptotic Giant Branch in the LMC, SMC and the Galactic Center
Mass loss on the AGB is extremely important for galactic chemical evolution but is poorly understood. A data set of a coherently selected sample of AGB stars is required to resolve this issue. The VLT with its...
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Chapter and Conference Paper
The Progenitors of Planetary Nebulae
Based on a new sample of (IRAS based) OH/IR stars (te Lintel Hekkert et al., 1991, A&AS, in press), and a catalogue of planetary nebulae compiled by Acker (1983, A&AS, 54, 315), we show the relation between th...
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Chapter and Conference Paper
The Peculiar Planetary Nebula M1-78
The question of whether Ml-78 is a PN or a compact H II region is discussed. We have obtained new high resolution radio continuum maps, optical spectra and CO maps. Arguments for it being a PN include spectral...
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Chapter and Conference Paper
Planetary Nebulae Near the Galactic Center I: Method of Discovery and Preliminary Results
A method is described for finding planetary nebulae. Use is made of the far infrared IRAS colors and radio continuum measurements. The method is applied here to a region within 15° of the galactic center. The ...
