Eric Depagne | SOUTH AFRICAN ASTRONOMICAL OBSERVATORY (original) (raw)
Papers by Eric Depagne
Astronomy and Astrophysics, Aug 24, 2000
Publ Astron Soc Pac, 2010
ABSTRACT We present fitted UBVRI - ZYUBVRI-ZY and u ′′ g ′′ r ′′ i ′′ z ′′ u′′g′′r′′i′′z′′ magnit... more ABSTRACT We present fitted UBVRI - ZYUBVRI-ZY and u ′′ g ′′ r ′′ i ′′ z ′′ u′′g′′r′′i′′z′′ magnitudes, spectral types, and distances for 2.4 million stars, derived from synthetic photometry of a library spectrum that best matches the Tycho2 BTVTBTVT, NOMAD RNRN, and 2MASS JHK2/SJHK2/S catalog magnitudes. We present similarly synthesized multifilter magnitudes, types, and distances for 4.8 million stars with 2MASS and SDSS photometry to g < 16g
Astronomy and Astrophysics, Mar 26, 2002
We present a high-resolution spectroscopic analysis of the bright (V=11.7), extreme halo giant CS... more We present a high-resolution spectroscopic analysis of the bright (V=11.7), extreme halo giant CS31082-001 ([Fe/H] = -2.9), obtained in an ESO-VLT Large Programme dedicated to very metal-poor stars. We find CS31082-001 to be extremely rich in r-process elements, comparable in this respect only to the similarly metal-poor, but carbon-enriched, giant CS22892-052. As a result of the extreme overabundance of the heaviest r-process elements, and negligible blending from CH and CN molecular lines, a reliable measurement is obtained of the U II line at 386 nm, for the first time in a halo star, along with numerous lines of Th II, as well as lines of 25 other r-process elements. Abundance estimates for a total of 43 elements are reported in CS31082-001, almost half of the entire periodic table. All elements with 56 \leq Z \leq 72 follow the Solar r-element pattern, reduced by about 1.25 dex ([r/Fe]=+1.7 dex, a factor 50). Pb, in contrast, seems to be below the shifted Solar r-process distribution, possibly indicating an error in the latter, while thorium is more enhanced than the lighter nuclides. Thus, while a universal production ratio for the r-process elements seems to hold in the interval 56 \leq Z \leq 72, it breaks down in the actinide region. When available, the U/Th is thus preferable to Th/Eu for radioactive dating: (i) because of its faster decay rate and smaller sensitivity to observational errors, and (ii) because the inital production ratio of the neighboring nuclides 238U and 232Th is more robustly predicted than the 151Eu/232Th ratio. Our current best estimate for the age of CS31082-001 is 14.0+/-2.4 Gyr.
Ground-based and Airborne Instrumentation for Astronomy V, 2014
Arxiv preprint astro-ph/ …, 2000
![Research paper thumbnail of First stars IX - Mixing in extremely metal-poor giants. Variation of the 12 C/ 13 C , [Na/Mg] and [Al/Mg] ratios](https://attachments.academia-assets.com/54798230/thumbnails/1.jpg)
](Astronomy and Astrophysics, 2006
Astronomy and Astrophysics, 2004
Astronomy and Astrophysics, 2003
Astronomy and Astrophysics, 2007
Astronomy and Astrophysics, 2002
Astronomy and Astrophysics, 2004
![Research paper thumbnail of Lithium Depletion in a [Fe/H]= -3.4 star?](https://attachments.academia-assets.com/39595548/thumbnails/1.jpg)
](Proceedings of the International Astronomical Union
Astronomy and Astrophysics
High-resolution spectra of the extremely metal-poor double-lined spectroscopic binary star BPS CS... more High-resolution spectra of the extremely metal-poor double-lined spectroscopic binary star BPS CS 22873-139 have been analyzed to determine the metallicity and abundance ratios for a number of elements. From the analysis of the collected radial velocities, new orbital elements are derived as well as an improved mass ratio. In spite of its extreme metal deficiency, [Fe/H]= -3.4, the abundance ratios of CS 22873-139 are not similar to those of a typical Population II star. In particular, the α-elements are not enhanced relative to iron, and the strontium abundance is very low. The abundance pattern of CS 22873-139 is compared to the patterns exhibited by other metal-poor stars which exhibit also very low strontium abundances. There is a large spread of elemental abundance ratios among these stars, suggesting that low strontium abundance may be associated with a variety of nucleosynthesis histories. The abundance ratios of CS 22873-139 are, surprisingly, very similar to those found in ...
ESO ASTROPHYSICS SYMPOSIA, 2006
This paper reports on the abundance determination of neutron-capture elements in 32 extremely met... more This paper reports on the abundance determination of neutron-capture elements in 32 extremely metal-poor stars. The study is based on the analysis of high quality spectra obtained with UVES+Kueyen. The results are compared with the most recent analyses of spectra mostly taken with other 10m class telescopes.
ESO ASTROPHYSICS SYMPOSIA, 2000
The orbital elements of CS 22873-139 have been revisited and preliminary abundance ratios in this... more The orbital elements of CS 22873-139 have been revisited and preliminary abundance ratios in this extremely metal poor binary star with [Fe/H] »</font >\approx -3.6 are given.
Sulfur is important: the site of its formation is uncertain, and at very low metallicity the tren... more Sulfur is important: the site of its formation is uncertain, and at very low metallicity the trend of [S/Fe] against [Fe/H] is controversial. Below [Fe/H]=-2.0, [S/Fe] remains constant or it decreases with [Fe/H], depending on the author and the multiplet used in the analysis. Moreover, although sulfur is not significantly bound in dust grains in the ISM, it seems to
Astrophysics and Space Science Proceedings, 2009
The observations were performed during several runs from April 2000 to November 2001 with the VLT... more The observations were performed during several runs from April 2000 to November 2001 with the VLT-UT2 and the high-resolution spectrograph UVES. (3 data files).
The Variable Star One-shot Project (VSOP) aimed at providing to the world-wide stellar community ... more The Variable Star One-shot Project (VSOP) aimed at providing to the world-wide stellar community the necessary one-shot spectrum of unstudied variable stars, too often classified as such by an analysis of photometric data only. The VSOP has established an new kind of observational model, where all steps from observations to spectral analysis, are automatized (or are underway to be fully automatized). The project is centralized on a collaborative Wiki website. The VSOP operational model is very successful, data are continuously flowing and being analyzed, and VSOP is now a worldwide open collaboration of people with very different and complementary skills and expertise. The idea of a central Wiki website has been extended by one of us to propose a new service to the whole astronomical community, called Wikimbad. Wikimbad is an open Wiki website aimed at collecting, organizing and making publicly available all kind of reduced and published astronomical data. Its strengths and a compar...
Astronomy and Astrophysics, Aug 24, 2000
Publ Astron Soc Pac, 2010
ABSTRACT We present fitted UBVRI - ZYUBVRI-ZY and u ′′ g ′′ r ′′ i ′′ z ′′ u′′g′′r′′i′′z′′ magnit... more ABSTRACT We present fitted UBVRI - ZYUBVRI-ZY and u ′′ g ′′ r ′′ i ′′ z ′′ u′′g′′r′′i′′z′′ magnitudes, spectral types, and distances for 2.4 million stars, derived from synthetic photometry of a library spectrum that best matches the Tycho2 BTVTBTVT, NOMAD RNRN, and 2MASS JHK2/SJHK2/S catalog magnitudes. We present similarly synthesized multifilter magnitudes, types, and distances for 4.8 million stars with 2MASS and SDSS photometry to g < 16g
Astronomy and Astrophysics, Mar 26, 2002
We present a high-resolution spectroscopic analysis of the bright (V=11.7), extreme halo giant CS... more We present a high-resolution spectroscopic analysis of the bright (V=11.7), extreme halo giant CS31082-001 ([Fe/H] = -2.9), obtained in an ESO-VLT Large Programme dedicated to very metal-poor stars. We find CS31082-001 to be extremely rich in r-process elements, comparable in this respect only to the similarly metal-poor, but carbon-enriched, giant CS22892-052. As a result of the extreme overabundance of the heaviest r-process elements, and negligible blending from CH and CN molecular lines, a reliable measurement is obtained of the U II line at 386 nm, for the first time in a halo star, along with numerous lines of Th II, as well as lines of 25 other r-process elements. Abundance estimates for a total of 43 elements are reported in CS31082-001, almost half of the entire periodic table. All elements with 56 \leq Z \leq 72 follow the Solar r-element pattern, reduced by about 1.25 dex ([r/Fe]=+1.7 dex, a factor 50). Pb, in contrast, seems to be below the shifted Solar r-process distribution, possibly indicating an error in the latter, while thorium is more enhanced than the lighter nuclides. Thus, while a universal production ratio for the r-process elements seems to hold in the interval 56 \leq Z \leq 72, it breaks down in the actinide region. When available, the U/Th is thus preferable to Th/Eu for radioactive dating: (i) because of its faster decay rate and smaller sensitivity to observational errors, and (ii) because the inital production ratio of the neighboring nuclides 238U and 232Th is more robustly predicted than the 151Eu/232Th ratio. Our current best estimate for the age of CS31082-001 is 14.0+/-2.4 Gyr.
Ground-based and Airborne Instrumentation for Astronomy V, 2014
Arxiv preprint astro-ph/ …, 2000
Astronomy and Astrophysics, 2006
Astronomy and Astrophysics, 2004
Astronomy and Astrophysics, 2003
Astronomy and Astrophysics, 2007
Astronomy and Astrophysics, 2002
Astronomy and Astrophysics, 2004
Proceedings of the International Astronomical Union
Astronomy and Astrophysics
High-resolution spectra of the extremely metal-poor double-lined spectroscopic binary star BPS CS... more High-resolution spectra of the extremely metal-poor double-lined spectroscopic binary star BPS CS 22873-139 have been analyzed to determine the metallicity and abundance ratios for a number of elements. From the analysis of the collected radial velocities, new orbital elements are derived as well as an improved mass ratio. In spite of its extreme metal deficiency, [Fe/H]= -3.4, the abundance ratios of CS 22873-139 are not similar to those of a typical Population II star. In particular, the α-elements are not enhanced relative to iron, and the strontium abundance is very low. The abundance pattern of CS 22873-139 is compared to the patterns exhibited by other metal-poor stars which exhibit also very low strontium abundances. There is a large spread of elemental abundance ratios among these stars, suggesting that low strontium abundance may be associated with a variety of nucleosynthesis histories. The abundance ratios of CS 22873-139 are, surprisingly, very similar to those found in ...
ESO ASTROPHYSICS SYMPOSIA, 2006
This paper reports on the abundance determination of neutron-capture elements in 32 extremely met... more This paper reports on the abundance determination of neutron-capture elements in 32 extremely metal-poor stars. The study is based on the analysis of high quality spectra obtained with UVES+Kueyen. The results are compared with the most recent analyses of spectra mostly taken with other 10m class telescopes.
ESO ASTROPHYSICS SYMPOSIA, 2000
The orbital elements of CS 22873-139 have been revisited and preliminary abundance ratios in this... more The orbital elements of CS 22873-139 have been revisited and preliminary abundance ratios in this extremely metal poor binary star with [Fe/H] »</font >\approx -3.6 are given.
Sulfur is important: the site of its formation is uncertain, and at very low metallicity the tren... more Sulfur is important: the site of its formation is uncertain, and at very low metallicity the trend of [S/Fe] against [Fe/H] is controversial. Below [Fe/H]=-2.0, [S/Fe] remains constant or it decreases with [Fe/H], depending on the author and the multiplet used in the analysis. Moreover, although sulfur is not significantly bound in dust grains in the ISM, it seems to
Astrophysics and Space Science Proceedings, 2009
The observations were performed during several runs from April 2000 to November 2001 with the VLT... more The observations were performed during several runs from April 2000 to November 2001 with the VLT-UT2 and the high-resolution spectrograph UVES. (3 data files).
The Variable Star One-shot Project (VSOP) aimed at providing to the world-wide stellar community ... more The Variable Star One-shot Project (VSOP) aimed at providing to the world-wide stellar community the necessary one-shot spectrum of unstudied variable stars, too often classified as such by an analysis of photometric data only. The VSOP has established an new kind of observational model, where all steps from observations to spectral analysis, are automatized (or are underway to be fully automatized). The project is centralized on a collaborative Wiki website. The VSOP operational model is very successful, data are continuously flowing and being analyzed, and VSOP is now a worldwide open collaboration of people with very different and complementary skills and expertise. The idea of a central Wiki website has been extended by one of us to propose a new service to the whole astronomical community, called Wikimbad. Wikimbad is an open Wiki website aimed at collecting, organizing and making publicly available all kind of reduced and published astronomical data. Its strengths and a compar...