From VLT/NACO diffraction-limited images of RY~Sgr, we report the first direct detection of heterogeneities in the circumstellar envelope of a R Coronae Borealis variable star. Several bright and very large dust clouds are seen in various directions at several hundred stellar radii from RY Sgr, revealing high activity for the ejection of...
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2004 (v1)Journal articleUploaded on: December 4, 2022
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November 14, 2006 (v1)Publication
AIMS: After the first dredge-up, low-mass Red Giant Branch (RGB) stars experience an extra-mixing episode that strongly affects the chemical abundances on their surface. This mixing occurs at the bump in the luminosity function. In this Letter we describe the efficiency of the extra-mixing in RGB stars found in very metal-poor globular clusters...
Uploaded on: March 25, 2023 -
April 1, 2008 (v1)Publication
We present new results of our ongoing chemical study of carbon stars in Local Group galaxies to test the critical dependence of $s$-process nucleosynthesis on the stellar metallicity. We collected optical spectra with the VLT/UVES instrument of two carbon stars found in the Carina Dwarf Spheroidal (dSph) galaxy, namely ALW-C6 and ALW-C7. We...
Uploaded on: December 4, 2022 -
February 1, 2007 (v1)Publication
R Coronae Borealis variable stars are suspected to sporadically eject optically thick dust clouds causing, when one of them lies on the line-of-sight, a huge brightness decline in visible light. Mid-infrared interferometric observations of RYSgr allowed us to explore the circumstellar regions very close to the central star (~20-40 mas) in order...
Uploaded on: February 28, 2023 -
August 2006 (v1)Journal article
Aims.Analysis of the innermost regions of the carbon-rich star IRC+10216 and of the outer layers of its circumstellar envelope have been performed in order to constrain its mass-loss history. Methods: .We analyzed the high dynamic range of near-infrared adaptive optics and the deep V-band images of the circumstellar envelope of IRC+10216 using...
Uploaded on: February 28, 2023 -
April 24, 2017 (v1)Conference paper
International audience
Uploaded on: December 4, 2022 -
April 2021 (v1)Journal article
Context. A fundamental element of galaxy formation is the accretion of mass through mergers of satellites or gas. Recent dynamical analyses based on Gaia data have revealed major accretion events in the history of the Milky Way. Nevertheless, our understanding of the primordial Galaxy is hindered because the bona fide identification of the most...
Uploaded on: December 4, 2022 -
2023 (v1)Journal article
Tidal streams of disrupted clusters are powerful probes of the gravitational potential of the Galaxy and they are routinely detected in the stellar halo of the Milky Way. It was recently shown that tidal streams of open clusters can now also be detected within the Milky Way disc. In this work, we highlight the fact that disc tidal streams also...
Uploaded on: November 25, 2023