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The detection of circumstellar water vapour around the ageing carbon star IRC +10216 challenged the current understanding of chemistry in old stars, because water was predicted to be almost absent in carbon-rich stars. Several explanations for the water were postulated, including the vaporization of icy bodies (comets or dwarf planets) in orbit around the(More)
With a luminosity >10 5 L and a mass-loss rate of ∼2 × 10 −4 M yr −1 , the red supergiant VY CMa truly is a spectacular object. Because of its extreme evolutionary state, it could explode as supernova any time. Studying its circumstellar material, into which the supernova blast will run, provides interesting constraints on supernova explosions and on the(More)
(Affiliations are available in the online edition) ABSTRACT The interstellar medium is enriched primarily by matter ejected from evolved low and intermediate mass stars. The outflows from these stars create a circumstellar envelope in which a rich gas-phase and dust-nucleation chemistry takes place. We observed the nearest carbon-rich evolved star, IRC(More)
We present Gemini-North GMOS/IFU observations of a young star cluster and its environment near the centre of the dwarf irregular starburst galaxy NGC 1569. This forms part of a larger and ongoing study of the formation and collimation mechanisms of galactic winds, including three additional IFU pointings in NGC 1569 covering the base of the galactic wind(More)
Recent R-matrix calculations of electron impact excitation rates in K v are used to derive the nebular emission line ratio R = I(4122.6 A)/I(4163.3 A) as a function of electron density (N(e)). This ratio is found to be very sensitive to changes in N(e) over the density range 10(3) to 10(6) cm(-3), but does not vary significantly with electron temperature,(More)
Context. A planetary nebula (PN) candidate was discovered during FORS imaging of the Local Group dwarf galaxy Phoenix. Aims. Use this PN to complement abundances from red-giant stars. Methods. FORS spectroscopy was used to confirm the PN classification. Empirical methods and photoionization modelling were used to derive elemental abundances from the(More)
MESS (Mass-loss of Evolved StarS) is a guaranteed time key program that uses the PACS and SPIRE instruments on board the Herschel space observatory to observe a representative sample of evolved stars, that include asymptotic giant branch (AGB) and post-AGB stars, planetary nebulae and red supergiants, as well as luminous blue variables, Wolf-Rayet stars and(More)
A VLT VIMOS study of the anomalous BCD Mrk 996: mapping the ionised gas kinematics and abundances † †Based on observations made with ESO telescopes at the Paranal Observatory under programme ID 078.B-0353(A) ABSTRACT A study of the blue compact dwarf (BCD) galaxy Mrk 996 based on high resolution optical VLT VIMOS integral field unit spectroscopy is(More)
Herschel PACS and SPIRE images have been obtained over a 30 × 30 area around the well-known carbon star CW Leo (IRC +10 216). An extended structure is found in an incomplete arc of ∼22 diameter, which is cospatial with the termination shock due to interaction with the interstellar medium (ISM) as defined by Sahai & Chronopoulos from ultraviolet GALEX(More)