Examinando por Autor "Bouy, H."

Mostrando 1 - 7 de 7

Acceso Abierto
Chamaeleon DANCe Revisiting the stellar populations of Chamaeleon I and Chamaeleon II with Gaia-DR2 data
(EDP Sciences, 2021-02-04) Galli, P. A. B.; Bouy, H.; Olivares, J.; Miret Roig, N.; Sarro, L. M.; Barrado, D.; Berihuete, A.; Bertín, E.; Cuillandre, J. C.; European Research Council (ERC); Berihuete, A. [0000-0002-8589-4423]; Galli, P. A. B. [0000-0003-2271-9297]; Olivares Romero, J. [0000-0003-0316-2956]
Context. Chamaeleon is the southernmost low-mass star-forming complex within 200 pc from the Sun. Its stellar population has been extensively studied in the past, but the current census of the stellar content is not complete yet and deserves further investigation. Aims. We take advantage of the second data release of the Gaia space mission to expand the census of stars in Chamaeleon and to revisit the properties of the stellar populations associated to the Chamaeleon I (Cha I) and Chamaeleon II (Cha II) dark clouds. Methods. We perform a membership analysis of the sources in the Gaia catalogue over a field of 100 deg2 encompassing the Chamaeleon clouds, and use this new census of cluster members to investigate the 6D structure of the complex. Results. We identify 188 and 41 high-probability members of the stellar populations in Cha I and Cha II, respectively, including 19 and 7 new members. Our sample covers the magnitude range from G = 6 to G = 20 mag in Cha I, and from G = 12 to G = 18 mag in Cha II. We confirm that the northern and southern subgroups of Cha I are located at different distances (191.4−0.8+0.8 pc and 186.7−1.0+1.0 pc), but they exhibit the same space motion within the reported uncertainties. Cha II is located at a distance of 197.5−0.9+1.0 pc and exhibits a space motion that is consistent with Cha I within the admittedly large uncertainties on the spatial velocities of the stars that come from radial velocity data. The median age of the stars derived from the Hertzsprung-Russell diagram and stellar models is about 1−2 Myr, suggesting that they are somewhat younger than previously thought. We do not detect significant age differences between the Chamaeleon subgroups, but we show that Cha II exhibits a higher fraction of disc-bearing stars compared to Cha I. Conclusions. This study provides the most complete sample of cluster members associated to the Chamaeleon clouds that can be produced with Gaia data alone. We use this new census of stars to revisit the 6D structure of this region with unprecedented precision.
Acceso Abierto
Corona-Australis DANCe. I. Revisiting the census of stars with Gaia-DR2 data
(EDP Sciences, 2020-02-13) Galli, P. A. B.; Bouy, H.; Olivares, J.; Miret Roig, N.; Sarro, L. M.; Barrado, D.; Berihuete, A.; Brandner, W.; European Research Council (ERC); Agence Nationale de la Recherche (ANR); Agencia Estatal de Investigación (AEI); Sarro, L. M. [0000-0002-5622-5191; 0000-0002-5971-9242; 0000-0002-8589-4423; 0000-0003-2271-9297; 0000-0001-5292-0421; 0000-0003-0316-2956; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. Corona-Australis is one of the nearest regions to the Sun with recent and ongoing star formation, but the current picture of its stellar (and substellar) content is not complete yet. Aims. We take advantage of the second data release of the Gaia space mission to revisit the stellar census and search for additional members of the young stellar association in Corona-Australis. Methods. We applied a probabilistic method to infer membership probabilities based on a multidimensional astrometric and photometric data set over a field of 128 deg2 around the dark clouds of the region. Results. We identify 313 high-probability candidate members to the Corona-Australis association, 262 of which had never been reported as members before. Our sample of members covers the magnitude range between G ≳ 5 mag and G ≲ 20 mag, and it reveals the existence of two kinematically and spatially distinct subgroups. There is a distributed “off-cloud” population of stars located in the north of the dark clouds that is twice as numerous as the historically known “on-cloud” population that is concentrated around the densest cores. By comparing the location of the stars in the HR-diagram with evolutionary models, we show that these two populations are younger than 10 Myr. Based on their infrared excess emission, we identify 28 Class II and 215 Class III stars among the sources with available infrared photometry, and we conclude that the frequency of Class II stars (i.e. “disc-bearing” stars) in the on-cloud region is twice as large as compared to the off-cloud population. The distance derived for the Corona-Australis region based on this updated census is d = 149.4 +0.4−0.4 pc, which exceeds previous estimates by about 20 pc. Conclusions. In this paper we provide the most complete census of stars in Corona-Australis available to date that can be confirmed with Gaia data. Furthermore, we report on the discovery of an extended and more evolved population of young stars beyond the region of the dark clouds, which was extensively surveyed in the past.
Acceso Abierto
Lithium-rotation connection in the newly discovered young stellar stream Psc–Eri (Meingast 1)
(EDP Sciences, 2020-03-31) Arancibia Silva, J.; Bouvier, J.; Bayo, A.; Galli, P. A. B.; Brandner, W.; Bouy, H.; Barrado, D.; Agencia Estatal de Investigación (AEI); Comisión Nacional de Investigación Científica y Tecnológica (CONICYT); Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT); European Research Council (ERC); Agence Nationale de la Recherche (ANR); Barrado, D. [0000-0002-5971-9242]; Galli, P. [0000-0003-2271-9297]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. As a fragile element, lithium is a sensitive probe of physical processes occurring in stellar interiors. Aims. We aim to investigate the relationship between lithium abundance and rotation rate in low-mass members of the newly discovered 125 Myr-old Psc–Eri stellar stream. Methods. We obtained high-resolution optical spectra and measured the equivalent width of the 607.8 nm LiI line for 40 members of the Psc–Eri stream, whose rotational periods have been previously derived. Results. We show that a tight correlation exists between the lithium content and rotation rate among the late-G to early-K-type stars of the Psc–Eri stream. Fast rotators are systematically Li rich, while slow rotators are Li depleted. This trend mimics that previously reported for the similar age Pleiades cluster. Conclusions. The lithium-rotation connection thus seems to be universal over a restricted effective temperature range for low-mass stars at or close to the zero-age main sequence, and does not depend on environmental conditions.
Acceso Abierto
Lithium-rotation connection in the newly discovered young stellar stream Psc-Eri (Meingast 1) (Corrigendum)
(EDP Sciences, 2020-08-07) Arrancibia Silva, J.; Bouvier, J.; Bayo, A.; Galli, P. A. B.; Brandner, W.; Bouy, H.; Barrado, D.; Comisión Nacional de Investigación Científica y Tecnológica (CONICYT); Agencia Estatal de Investigación (AEI); European Research Council (ERC); Agence Nationale de la Recherche (ANR); Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT); Navascues Barrado, D. [0000-0002-5971-9242]; Galli, P. [0000-0003-2271-9297]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. As a fragile element, lithium is a sensitive probe of physical processes occurring in stellar interiors. Aims. We aim to investigate the relationship between lithium abundance and rotation rate in low-mass members of the newly discovered 125 Myr-old Psc–Eri stellar stream. Methods. We obtained high-resolution optical spectra and measured the equivalent width of the 607.8 nm LiI line for 40 members of the Psc–Eri stream, whose rotational periods have been previously derived. Results. We show that a tight correlation exists between the lithium content and rotation rate among the late-G to early-K-type stars of the Psc–Eri stream. Fast rotators are systematically Li rich, while slow rotators are Li depleted. This trend mimics that previously reported for the similar age Pleiades cluster. Conclusions. The lithium-rotation connection thus seems to be universal over a restricted effective temperature range for low-mass stars at or close to the zero-age main sequence, and does not depend on environmental conditions.
Acceso Abierto
Lupus DANCe Census of stars and 6D structure with Gaia-DR2 data
(EDP Sciences, 2020-11-16) Galli, P. A. B.; Bouy, H.; Olivares, J.; Miret Roig, N.; Vieira, R. G.; Sarro, L. M.; Barrado, D.; Berihuete, A.; Bertout, C.; Bertín, E.; Cuillandre, J. C.; European Research Council (ERC); Agencia Estatal de Investigación (AEI); Agence Nationale de la Recherche (ANR); Berihuete, A. [0000-0002-8589-4423]; Georgetti Vieira, R. [0000-0002-3607-3979]; Galli, P. [0000-0003-2271-9297]; Olivares Romero, J. [0000-0003-0316-2956]; Sarro, L. M. [0000-0002-5622-5191]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. Lupus is recognised as one of the closest star-forming regions, but the lack of trigonometric parallaxes in the pre-Gaia era hampered many studies on the kinematic properties of this region and led to incomplete censuses of its stellar population. Aims. We use the second data release of the Gaia space mission combined with published ancillary radial velocity data to revise the census of stars and investigate the 6D structure of the Lupus complex. Methods. We performed a new membership analysis of the Lupus association based on astrometric and photometric data over a field of 160 deg2 around the main molecular clouds of the complex and compared the properties of the various subgroups in this region. Results. We identified 137 high-probability members of the Lupus association of young stars, including 47 stars that had never been reported as members before. Many of the historically known stars associated with the Lupus region identified in previous studies are more likely to be field stars or members of the adjacent Scorpius-Centaurus association. Our new sample of members covers the magnitude and mass range from G ≃ 8 to G ≃ 18 mag and from 0.03 to 2.4 M⊙, respectively. We compared the kinematic properties of the stars projected towards the molecular clouds Lupus 1–6 and showed that these subgroups are located at roughly the same distance (about 160 pc) and move with the same spatial velocity. Our age estimates inferred from stellar models show that the Lupus subgroups are coeval (with median ages ranging from about 1 to 3 Myr). The Lupus association appears to be younger than the population of young stars in the Corona-Australis star-forming region recently investigated by our team using a similar methodology. The initial mass function of the Lupus association inferred from the distribution of spectral types shows little variation compared to other star-forming regions. Conclusions. In this paper, we provide an updated sample of cluster members based on Gaia data and construct the most complete picture of the 3D structure and 3D space motion of the Lupus complex.
Acceso Abierto
Pleiades or Not? Resolving the Status of the Lithium-rich M Dwarfs HHJ 339 and HHJ 430
(The Institute of Physics (IOP), 2020-06-18) Stauffer, J.; Barrado, D.; David, T.; Rebull, L. M.; Hillenbrand, L. A.; Mamajek, E. E.; Oppenheimer, R.; Aigrain, S.; Bouy, H.; Lillo Box, J.; Agencia Estatal de Investigación (AEI); National Aeronautics and Space Administration (NASA); Stauffer, J. [0000-0003-3595-7382]; David, T. [0000-0001-6534-6246]; Rebull, L. M. [0000-0001-6381-515X]; Mamajek, E. E. [0000-0003-2008-1488]; Oppenheimer, R. [0000-0001-7130-7681]; Aigrain, S. [0000-0003-1453-0574]; Bouy, H. [0000-0002-7084-487X]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Oppenheimer et al. discovered two M5 dwarfs in the Pleiades with nearly primordial lithium. These stars are not low enough in mass to represent the leading edge of the lithium depletion boundary at Pleiades age (~125 Myr). A possible explanation for the enhanced lithium in these stars is that they are actually not members of the Pleiades but instead are members of a younger moving group seen in projection toward the Pleiades. We have used data from Gaia DR2 to confirm that these two stars, HHJ 339 and HHJ 430, are indeed not members of the Pleiades. Based on their space motions, parallaxes, and positions in a Gaia-based color–magnitude diagram, it is probable that these two stars are about 40 parsecs foreground to the Pleiades and have ages of ~25 Myr. Kinematically they are best matched to the 32 Ori moving group.
Acceso Abierto
Searching for debris discs in the 30 Myr open cluster IC 4665
(EDP Sciences, 2020-09-24) Miret Roig, N.; Huélamo, N.; Bouy, H.; European Research Council (ERC); Agencia Estatal de Investigación (AEI); Miret Roig, N. [0000-0001-5292-0421]; Huelamo, N. [0000-0002-2711-8143]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. Debris discs orbiting young stars are key to understanding dust evolution and the planetary formation process. We take advantage of a recent membership analysis of the 30 Myr nearby open cluster IC 4665 based on the Gaia and DANCe surveys to revisit the disc population of this cluster. Aims. We aim to study the disc population of IC 4665 using Spitzer (MIPS and IRAC) and WISE photometry. Methods. We use several colour–colour diagrams with empirical photospheric sequences to detect the sources with an infrared excess. Independently, we also fit the spectral energy distribution (SED) of our debris-disc candidates with the Virtual Observatory SED analyser (VOSA) which is capable of automatically detecting infrared excesses and provides effective temperature estimates. Results. We find six candidate debris-disc host stars (five with MIPS and one with WISE), two of which are new candidates. We estimate a disc fraction of 24 ± 10% for the B–A stars, where our sample is expected to be complete. This is similar to what has been reported in other clusters of similar ages (Upper Centaurus Lupus, Lower Centaurus Crux, the β Pictoris moving group, and the Pleiades). For solar-type stars we find a disc fraction of 9 ± 9%, which is lower than that observed in regions with comparable ages. Conclusions. Our candidate debris-disc host stars are excellent targets to be studied with ALMA or the future James Webb Space Telescope (JWST).