Search

Your search keyword '"Nordlander, T."' showing total 43 results
Start Over Author "Nordlander, T." Language english
43 results on '"Nordlander, T."'

2. Metallicities for more than 10 million stars derived from Gaia BP/RP spectra.

Author

Xylakis-Dornbusch, T., Christlieb, N., Hansen, T. T., Nordlander, T., Webber, K. B., and Marshall, J.

Subjects
STELLAR populations, STARS, DEMOGRAPHIC surveys, STAR formation, MILKY Way
Abstract

Context. The third Gaia Data Release, which includes BP/RP spectra for 219 million sources, has opened a new window into the exploration of the chemical history and evolution of the Milky Way. The wealth of information encapsulated in these data is far greater than their low resolving power (R ~ 50) would suggest at first glance, as shown in many studies. We zeroed in on the use of these data for the purpose of the detection of "new" metal-poor stars, which are hard to find yet essential for understanding several aspects of the origin of the Galaxy, star formation, and the creation of the elements, among other topics. Aims. We strive to refine a metal-poor candidate selection method that was developed with simulated Gaia BP/RP spectra with the ultimate objective of providing the community with both a recipe to select stars for medium and high resolution observations, and a catalog of stellar metallicities. Methods. We used a dataset comprised of GALAH DR3 and SAGA database stars in order to verify and adjust our selection method to real-world data. For that purpose, we used dereddening as a means to tackle the issue of extinction, and then we applied our fine-tuned method to select metal-poor candidates, which we thereafter observed and analyzed. Results. We were able to infer metallicities for GALAH DR3 and SAGA stars with color excesses up to E(B − V) < 1.5 and an uncertainty of σ[Fe/H]inf ∼ 0.36, which is good enough for the purpose of identifying new metal-poor stars. Further, we selected 26 metal-poor candidates via our method for observations. As spectral analysis showed, 100% of them had [Fe/H] < −2.0, 57% had [Fe/H] < −2.5, and 8% had [Fe/H] < −3.0. We inferred metallicities for these stars with an uncertainty of σ[Fe/H]inf ∼ 0.31, as was proven when comparing [Fe/H]inf to the spectroscopic [Fe/H]. Finally, we assembled a catalog of metallicities for 10 861 062 stars. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

3. High-resolution spectroscopic study of extremely metal-poor stars in the Large Magellanic Cloud.

Author

Oh, W S, Nordlander, T, Da Costa, G S, Bessell, M S, and Mackey, A D

Subjects
*LARGE magellanic cloud, *MAGELLANIC clouds, *GALACTIC halos, *MILKY Way, *STELLAR mergers, *STAR formation
Abstract

We present detailed abundance results based on Ultraviolet and Visual Echelle Spectrograph high-dispersion spectra for seven very and extremely metal-poor stars in the Large Magellanic Cloud (LMC). We confirm that all seven stars, two of which have [Fe/H] ≤ −3.0, are the most metal-poor stars discovered so far in the Magellanic Clouds. The element abundance ratios are generally consistent with Milky Way halo stars of similar [Fe/H] values. We find that two of the more metal-rich stars in our sample are enhanced in r-process elements. This result contrasts with the literature, where all nine metal-poor LMC stars with higher [Fe/H] values than our sample were found to be rich in r-process elements. The absence of r-process enrichment in stars with lower [Fe/H] values is consistent with a minimum delay time-scale of ∼100 Myr for the neutron star binary merger process to generate substantial r-process enhancements in the LMC. We find that the occurrence rate of r-process enhancement (r-I or r-II) in our sample of very and extremely metal-poor stars is statistically indistinguishable from that found in the Milky Way's halo, although including stars from the literature sample hints at a larger r-II frequency the LMC. Overall, our results shed light on the earliest epochs of star formation in the LMC that may be applicable to other galaxies of LMC-like mass. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

4. Atomic diffusion and mixing in old stars – VIII. Chemical abundance variations in the globular cluster M4 (NGC 6121).

Author

Nordlander, T, Gruyters, P, Richard, O, and Korn, A J

Subjects
*GLOBULAR clusters, *ASYMPTOTIC giant branch stars, *STELLAR structure, *OPEN clusters of stars, *STELLAR evolution, *VERY large telescopes
Abstract

Variations in chemical abundances with evolutionary phase have been identified among stars in globular and open clusters with a wide range of metallicities. In the metal-poor clusters, these variations compare well with predictions from stellar structure and evolution models considering the internal diffusive motions of atoms and ions, collectively known as atomic diffusion, when moderated by an additional mixing process with a fine-tuned efficiency. We present here an investigation of these effects in the Galactic globular cluster NGC 6121 (M4) ([Fe/H] = −1.13) through a detailed chemical abundance analysis of 86 stars using high-resolution ESO Very Large Telescope (VLT) Fibre Large Array Multi Element Spectrograph (FLAMES) spectroscopy. The stars range from the main-sequence turnoff point (TOP) to the red giant branch (RGB) just above the bump. We identify C-N-O and Mg-Al-Si abundance anticorrelations, and confirm the presence of a bimodal population differing by 1 dex in nitrogen abundance. The composition of the second-generation stars imply pollution from both massive (20–40  |$\rm M_{\odot }$|⁠) and asymptotic giant branch stars. We find evolutionary variations in chemical abundances between the TOP and RGB, which are robust to uncertainties in stellar parameters and modelling assumptions. The variations are weak, but match predictions well when employing efficient additional mixing. Without correcting for Galactic production of lithium, we derive an initial lithium abundance 2.63 ± 0.10, which is marginally lower than the predicted primordial big-bang nucleosynthesis value. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

5. The complex stellar system M 22: constraining the chemical enrichment from AGB stars using magnesium isotope ratios.

Author

McKenzie, M, Yong, D, Karakas, A I, Wang, E, Monty, S, Marino, A F, Milone, A P, Nordlander, T, Mura-Guzmán, A, Martell, S, and Carlos, M

Subjects
MAGNESIUM isotopes, ASYMPTOTIC giant branch stars, NEUTRON capture, STAR clusters, HEAVY elements
Abstract

The complex star cluster M 22 (NGC 6656) provides a unique opportunity for studying the slow neutron capture (s -)process nucleosynthesis at low metallicity due to its two stellar groups with distinct iron-peak and neutron capture element abundances. Previous studies attribute these abundance differences to pollution from |$3-6 \ \rm {M}_{\odot }$| asymptotic giant branch (AGB) stars which produce significant quantities of the neutron-rich Mg isotopes 25Mg and 26Mg. We report the first-ever measurements of Mg isotopic abundance ratios at |$\rm {[Fe/H]} \ \sim -2$| in a globular cluster-like system using very high-resolution and signal-to-noise spectra (R = 110 000, S/N  = 300 per pixel at 514 nm) from the VLT/UVES spectrograph for six stars; three in each s -process group. Despite the presence of star-to-star variations in 24Mg, 25Mg, and 26Mg, we find no correlation with heavy element abundances, implying that the nucleosynthetic source of s -process enrichment must not influence Mg isotope ratios. Instead, a key result of this work is that we identify correlations between 26Mg/24Mg and some light elements. Using a custom suite of AGB nucleosynthesis yields tailored to the metallicity of M 22, we find that low mass (⁠|$\sim 1 \rm {-} 3 \ \rm {M}_{\odot }$|⁠) AGB stars are capable of reproducing the observed s -process abundances of M 22 and that the absence of any difference in Mg isotope ratios between the two s -process groups precludes AGBs with masses above |$\sim 3 \ \rm {M}_{\odot }$|⁠. This places tighter constraints on possible formation scenarios and suggests an age difference of at least |$\sim 280 \rm {-} 480 \ \rm {Myr}$| between the two populations which is independent of isochrone fitting. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

6. The SkyMapper search for extremely metal-poor stars in the Large Magellanic Cloud

Author

Oh, W. S., Nordlander, T., Da Costa, G. S., Bessell, M. S., and Mackey, A. D.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Astrophysics - Astrophysics of Galaxies, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

We present results of a search for extremely metal-poor (EMP) stars in the Large Magellanic Cloud, which can provide crucial information about the properties of the first stars as well as on the formation conditions prevalent during the earliest stages of star formation in dwarf galaxies. Our search utilised SkyMapper photometry, together with parallax and proper motion cuts (from Gaia), colour-magnitude cuts (by selecting the red giant branch region) and finally a metallicity-sensitive cut. Low-resolution spectra of a sample of photometric candidates were taken using the ANU 2.3m telescope/WiFeS spectrograph, from which 7 stars with [Fe/H] $\leq$ -2.75 were identified, two of which have [Fe/H] $\leq$ -3. Radial velocities, derived from the CaII triplet lines, closely match the outer rotation curve of the LMC for the majority of the candidates in our sample. Therefore, our targets are robustly members of the LMC based on their 6D phase-space information (coordinates, spectrophotometric distance, proper motions and radial velocities), and they constitute the most metal-poor stars so far discovered in this galaxy., Accepted for publication in MNRAS

Published
2023

8. Raising the observed metallicity floor with a 3D non-LTE analysis of SDSS J102915.14+172927.9

Author

Lagae, C., Amarsi, A. M., Díaz, L. F. Rodríguez, Lind, K., Nordlander, T., Hansen, T. T., and Heger, A.

Subjects
stars, abundances, Population II [Stars], atomic processes, FOS: Physical sciences, Population III, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Population III [Stars], Astronomi, astrofysik och kosmologi, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, radiative transfer, Astrophysics of Galaxies (astro-ph.GA), abundances [Stars], atmospheres, Astronomy, Astrophysics and Cosmology, atmospheres [Stars], Solar and Stellar Astrophysics (astro-ph.SR), Population II
Abstract

Context: The first stars produced the first heavy elements and set the stage for the formation of the first galaxies. Accurate chemical abundances of ultra metal-poor stars ([Fe/H], 14 pages, 9 figures, Accepted for publication in Astronomy & Astrophysics

Published
2023
Full Text
View/download PDF

9. The SkyMapper search for extremely metal-poor stars in the Large Magellanic Cloud.

Author

Oh, W S, Nordlander, T, Da Costa, G S, Bessell, M S, and Mackey, A D

Subjects
*LARGE magellanic cloud, *DWARF stars, *PARALLAX, *DWARF galaxies, *EARLY stars, *STAR formation
Abstract

We present results of a search for extremely metal-poor stars in the Large Magellanic Cloud (LMC), which can provide crucial information about the properties of the first stars as well as on the formation conditions prevalent during the earliest stages of star formation in dwarf galaxies. Our search utilized SkyMapper photometry, together with parallax and proper motion cuts (from Gaia), colour–magnitude cuts (by selecting the red giant branch region), and finally a metallicity-sensitive cut. Low-resolution spectra of a sample of photometric candidates were taken using the ANU 2.3m telescope/WiFeS spectrograph, from which seven stars with |$\rm [Fe/H] \le -2.75$| were identified, two of which have |$\rm [Fe/H] \le -3$|⁠. Radial velocities, derived from the Ca  ii triplet lines, closely match the outer rotation curve of the LMC for the majority of the candidates in our sample. Therefore, our targets are robustly members of the LMC based on their 6D phase-space information (coordinates, spectrophotometric distance, proper motions, and radial velocities), and they constitute the most metal-poor stars so far discovered in this galaxy. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

10. Non-LTE abundance corrections for late-type stars from 2000 angstrom to 3 mu m

Author

Lind, K., Nordlander, T., Wehrhahn, A., Montelius, M., Osorio, Y., Barklem, P. S., and Afsar, M.

Subjects
stars: abundances, Evolution, stars: late-type, Sodium Abundance, Atom-Atom Collisions, Solar, Metal-Poor Stars, radiative transfer, stars: atmospheres, Nlte Determination, Na, Homogeneous Sample, techniques: spectroscopic, Line Formation, Aluminum
Abstract

Context. It is well known that cool star atmospheres depart from local thermodynamic equilibrium (LTE). Making an accurate abundance determination requires taking those effects into account, but the necessary non-LTE (hereafter NLTE) calculations are often lacking. Aims. Our goal is to provide detailed estimates of NLTE effects for FGK type stars for all spectral lines from the ultraviolet (UV) to the near infrared (NIR) that are potentially useful as abundance diagnostics. The first paper in this series focusses on the light elements Na, Mg, and Al. Methods. The code PySME was used to compute curves of growth for 2158 MARCS model atmospheres in the parameter range 3800 < T-eff < 8000 K, 0.0 < log(g) < 5.5, and -5 < [Fe/H] < +0.5. Two microturbulence values, 1 and 2 km s(-1), and nine abundance points spanning -1 < [X/Fe] < 1 for element X, are used to construct individual line curves of growth by calculating the equivalent widths of 35 Na lines, 134 Mg lines, and 34 Al lines. The lines were selected in the wavelength range between 2000 angstrom and 3 mu m. Results. We demonstrate the power of the new grids with LTE and NLTE abundance analysis by means of equivalent width measurements of five benchmark stars; the Sun, Arcturus, HD 84937, HD 140283 and HD 122563. For Na, the NLTE abundances are lower than in LTE and show markedly reduced line-to-line scatter in the metal-poor stars. For Mg, we confirm previous reports of a significant similar to 0.25 dex LTE ionisation imbalance in metal-poor stars that is only slightly improved in NLTE (similar to 0.18 dex). LTE abundances based on Mg II lines agree better with models of Galactic chemical evolution. For Al, NLTE calculations strongly reduce an similar to 0.6 dex ionisation imbalance seen in LTE for the metal-poor stars. The abundance corrections presented in this work are in good agreement with previous studies for the subset of lines that overlap, with the exception of strongly saturated lines. Conclusions. A consensus between different abundance diagnostics is the most powerful tool available to stellar spectroscopists to assess the accuracy of the models. Here we report that NLTE abundance analysis in general leads to improved agreement, in particular for metal-poor stars. The residual scatter is believed to be caused mainly by unresolved blends and/or poor atomic data, with the notable exception of Mg, which calls for further investigation., European Research Council (ERC) under the European Union [852977]; Swedish Research Council [202003404, 2018-05973]; UK Science and Technology Facility Council (STFC) [ST/M000958/1, ST/V000632/1]; Knut and Alice Wallenberg Foundation, K.L. and M.M. acknowledge funds from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant agreement No. 852977). The computations were enabled by resources provided by the Swedish National Infrastructure for Computing (SNIC) at UPPMAX, partially funded by the Swedish Research Council through grant agreement no. 2018-05973. C.K. acknowledges funding from the UK Science and Technology Facility Council (STFC) through grant ST/M000958/1 and ST/V000632/1. This work is supported by the Swedish Research Council through an individual project grant with contract No. 202003404. K.L. and P.B. acknowledge support by the Knut and Alice Wallenberg Foundation.

Published
2022

11. Non-LTE abundance corrections for late-type stars from 2000Å to 3 μm

Author

Lind, K., Nordlander, T., Wehrhahn, Ansgar, Montelius, M., Osorio, Y., Barklem, Paul S., Afsar, M., Sneden, C., and Kobayashi, C.

Subjects
abundances [stars], atmospheres [stars], Astronomi, astrofysik och kosmologi, radiative transfer, Astronomy, Astrophysics and Cosmology, late-type [stars], spectroscopic [techniques]
Abstract

Context. It is well known that cool star atmospheres depart from local thermodynamic equilibrium (LTE). Making an accurate abundance determination requires taking those effects into account, but the necessary non-LTE (hereafter NLTE) calculations are often lacking. Aims. Our goal is to provide detailed estimates of NLTE effects for FGK type stars for all spectral lines from the ultraviolet (UV) to the near infrared (NIR) that are potentially useful as abundance diagnostics. The first paper in this series focusses on the light elements Na, Mg, and Al. Methods. The code PySME was used to compute curves of growth for 2158 MARCS model atmospheres in the parameter range 3800 < T-eff < 8000 K, 0.0 < log(g) < 5.5, and -5 < [Fe/H] < +0.5. Two microturbulence values, 1 and 2 km s(-1), and nine abundance points spanning -1 < [X/Fe] < 1 for element X, are used to construct individual line curves of growth by calculating the equivalent widths of 35 Na lines, 134 Mg lines, and 34 Al lines. The lines were selected in the wavelength range between 2000 angstrom and 3 mu m. Results. We demonstrate the power of the new grids with LTE and NLTE abundance analysis by means of equivalent width measurements of five benchmark stars; the Sun, Arcturus, HD 84937, HD 140283 and HD 122563. For Na, the NLTE abundances are lower than in LTE and show markedly reduced line-to-line scatter in the metal-poor stars. For Mg, we confirm previous reports of a significant similar to 0.25 dex LTE ionisation imbalance in metal-poor stars that is only slightly improved in NLTE (similar to 0.18 dex). LTE abundances based on Mg II lines agree better with models of Galactic chemical evolution. For Al, NLTE calculations strongly reduce an similar to 0.6 dex ionisation imbalance seen in LTE for the metal-poor stars. The abundance corrections presented in this work are in good agreement with previous studies for the subset of lines that overlap, with the exception of strongly saturated lines. Conclusions. A consensus between different abundance diagnostics is the most powerful tool available to stellar spectroscopists to assess the accuracy of the models. Here we report that NLTE abundance analysis in general leads to improved agreement, in particular for metal-poor stars. The residual scatter is believed to be caused mainly by unresolved blends and/or poor atomic data, with the notable exception of Mg, which calls for further investigation. Title in WoS: Non-LTE abundance corrections for late-type stars from 2000 angstrom to 3 mu m

Published
2022

12. A high-resolution spectroscopic search for multiple populations in the 2 Gyr old cluster NGC 1846.

Author

Oh, W S, Nordlander, T, Da Costa, G S, and Mackey, A D

Subjects
*LARGE magellanic cloud, *STAR clusters, *STELLAR populations, *SUPERGIANT stars, *CONFIDENCE intervals
Abstract

We present detailed C, O, Na, Mg, Si, Ca, Ti, V, Fe, Zr, Ba, and Eu abundance measurements for 20 red giant branch (RGB) stars in the Large Magellanic Cloud (LMC) star cluster NGC 1846 ([Fe/H] = −0.59). This cluster is 1.95 Gyr old and lies just below the supposed lower age limit (2 Gyr) for the presence of multiple populations in massive star clusters. Our measurements are based on high- and low-resolution VLT/FLAMES spectra combined with photometric data from Hubble Space Telescope (HST). Corrections for non-local thermodynamic equilibrium effects are also included for O, Na, Mg, Si, Ca, Fe, and Ba. Our results show that there is no evidence for multiple populations in this cluster based on the lack of any intrinsic star-to-star spread in the abundances of Na and O: We place 95  per cent confidence limits on the intrinsic dispersion for these elements of ≤0.07 and ≤0.09 dex, respectively. However, we do detect a significant spread in the carbon abundances, indicating varying evolutionary mixing occurring on the RGB that increases with luminosity. Overall, the general abundance patterns for NGC 1846 are similar to those seen in previous studies of intermediate-age LMC star clusters and field stars. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

13. The GALAH survey: tracing the Galactic disc with open clusters.

Author

Spina, L, Ting, Y-S, De Silva, G M, Frankel, N, Sharma, S, Cantat-Gaudin, T, Joyce, M, Stello, D, Karakas, A I, Asplund, M B, Nordlander, T, Casagrande, L, D'Orazi, V, Casey, A R, Cottrell, P, Tepper-García, T, Baratella, M, Kos, J, Čotar, K, and Bland-Hawthorn, J

Subjects
OPEN clusters of stars, GALACTIC evolution, GALAXY clusters, FUNCTION spaces, STELLAR dynamics, ASTROMETRY, STAR clusters
Abstract

Open clusters are unique tracers of the history of our own Galaxy's disc. According to our membership analysis based on Gaia astrometry, out of the 226 potential clusters falling in the footprint of the GALactic Archaeology with HERMES (GALAH) survey or the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey, we find that 205 have secure members that were observed by at least one of the surveys. Furthermore, members of 134 clusters have high-quality spectroscopic data that we use to determine their chemical composition. We leverage this information to study the chemical distribution throughout the Galactic disc of 21 elements, from C to Eu. The radial metallicity gradient obtained from our analysis is −0.076 ± 0.009 dex kpc−1, which is in agreement with previous works based on smaller samples. Furthermore, the gradient in the [Fe/H]–guiding radius (r guid) plane is −0.073 ± 0.008 dex kpc−1. We show consistently that open clusters trace the distribution of chemical elements throughout the Galactic disc differently than field stars. In particular, at the given radius, open clusters show an age–metallicity relation that has less scatter than field stars. As such scatter is often interpreted as an effect of radial migration, we suggest that these differences are due to the physical selection effect imposed by our Galaxy: clusters that would have migrated significantly also had higher chances to get destroyed. Finally, our results reveal trends in the [X/Fe]– r guid–age space, which are important to understand production rates of different elements as a function of space and time. [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

14. Exploring the Galaxy's halo and very metal-weak thick disc with SkyMapper and Gaia DR2.

Author

Cordoni, G, Da Costa, G S, Yong, D, Mackey, A D, Marino, A F, Monty, S, Nordlander, T, Norris, J E, Asplund, M, Bessell, M S, Casey, A R, Frebel, A, Lind, K, Murphy, S J, Schmidt, B P, Gao, X D, Xylakis-Dornbusch, T, Amarsi, A M, and Milone, A P

Subjects
GRAVITATIONAL interactions, DWARF galaxies, GALAXIES, STELLAR orbits, GRAVITATIONAL energy, ASTROMETRY
Abstract

In this work, we combine spectroscopic information from the SkyMapper survey for Extremely Metal-Poor stars and astrometry from Gaia DR2 to investigate the kinematics of a sample of 475 stars with a metallicity range of |$-6.5 \le \rm [Fe/H] \le -2.05$| dex. Exploiting the action map, we identify 16 and 40 stars dynamically consistent with the Gaia Sausage and Gaia Sequoia accretion events, respectively. The most metal poor of these candidates have metallicities of |$\rm [Fe/H]=-3.31\, \mathrm{ and }\, -3.74$|⁠ , respectively, helping to define the low-metallicity tail of the progenitors involved in the accretion events. We also find, consistent with other studies, that ∼21 per cent of the sample have orbits that remain confined to within 3 kpc of the Galactic plane, that is, | Z max| ≤ 3 kpc. Of particular interest is a subsample (∼11 per cent of the total) of low | Z max| stars with low eccentricities and prograde motions. The lowest metallicity of these stars has [Fe/H] = –4.30 and the subsample is best interpreted as the very low-metallicity tail of the metal-weak thick disc population. The low | Z max|, low eccentricity stars with retrograde orbits are likely accreted, while the low | Z max|, high eccentricity pro- and retrograde stars are plausibly associated with the Gaia Sausage system. We find that a small fraction of our sample (∼4 per cent of the total) is likely escaping from the Galaxy, and postulate that these stars have gained energy from gravitational interactions that occur when infalling dwarf galaxies are tidally disrupted. [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

15. Gaia Data Release 1: Testing parallaxes with local Cepheids and RR Lyrae stars

Author

Clementini, G. Eyer, L. Ripepi, V. Marconi, M. Muraveva, T. Garofalo, A. Sarro, L.M. Palmer, M. Luri, X. Molinaro, R. Rimoldini, L. Szabados, L. Musella, I. Anderson, R.I. Prusti, T. De Bruijne, J.H.J. Brown, A.G.A. Vallenari, A. Babusiaux, C. Bailer-Jones, C.A.L. Bastian, U. Biermann, M. Evans, D.W. Jansen, F. Jordi, C. Klioner, S.A. Lammers, U. Lindegren, L. Mignard, F. Panem, C. Pourbaix, D. Randich, S. Sartoretti, P. Siddiqui, H.I. Soubiran, C. Valette, V. Van Leeuwen, F. Walton, N.A. Aerts, C. Arenou, F. Cropper, M. Drimmel, R. Høg, E. Katz, D. Lattanzi, M.G. O'Mullane, W. Grebel, E.K. Holland, A.D. Huc, C. Passot, X. Perryman, M. Bramante, L. Cacciari, C. Castañeda, J. Chaoul, L. Cheek, N. De Angeli, F. Fabricius, C. Guerra, R. Hernández, J. Jean-Antoine-Piccolo, A. Masana, E. Messineo, R. Mowlavi, N. Nienartowicz, K. Ordóñez-Blanco, D. Panuzzo, P. Portell, J. Richards, P.J. Riello, M. Seabroke, G.M. Tanga, P. Thévenin, F. Torra, J. Els, S.G. Gracia-Abril, G. Comoretto, G. Garcia-Reinaldos, M. Lock, T. Mercier, E. Altmann, M. Andrae, R. Astraatmadja, T.L. Bellas-Velidis, I. Benson, K. Berthier, J. Blomme, R. Busso, G. Carry, B. Cellino, A. Cowell, S. Creevey, O. Cuypers, J. Davidson, M. De Ridder, J. De Torres, A. Delchambre, L. Dell'Oro, A. Ducourant, C. Frémat, Y. García-Torres, M. Gosset, E. Halbwachs, J.-L. Hambly, N.C. Harrison, D.L. Hauser, M. Hestroffer, D. Hodgkin, S.T. Huckle, H.E. Hutton, A. Jasniewicz, G. Jordan, S. Kontizas, M. Korn, A.J. Lanzafame, A.C. Manteiga, M. Moitinho, A. Muinonen, K. Osinde, J. Pancino, E. Pauwels, T. Petit, J.-M. Recio-Blanco, A. Robin, A.C. Siopis, C. Smith, M. Smith, K.W. Sozzetti, A. Thuillot, W. Van Reeven, W. Viala, Y. Abbas, U. Abreu Aramburu, A. Accart, S. Aguado, J.J. Allan, P.M. Allasia, W. Altavilla, G. Álvarez, M.A. Alves, J. Andrei, A.H. Anglada Varela, E. Antiche, E. Antoja, T. Antón, S. Arcay, B. Bach, N. Baker, S.G. Balaguer-Núñez, L. Barache, C. Barata, C. Barbier, A. Barblan, F. Barrado, N.Y. Barros, M. Barstow, M.A. Becciani, U. Bellazzini, M. Bello García, A. Belokurov, V. Bendjoya, P. Berihuete, A. Bianchi, L. Bienaymé, O. Billebaud, F. Blagorodnova, N. Blanco-Cuaresma, S. Boch, T. Bombrun, A. Borrachero, R. Bouquillon, S. Bourda, G. Bragaglia, A. Breddels, M.A. Brouillet, N. Brüsemeister, T. Bucciarelli, B. Burgess, P. Burgon, R. Burlacu, A. Busonero, D. Buzzi, R. Caffau, E. Cambras, J. Campbell, H. Cancelliere, R. Cantat-Gaudin, T. Carlucci, T. Carrasco, J.M. Castellani, M. Charlot, P. Charnas, J. Chiavassa, A. Clotet, M. Cocozza, G. Collins, R.S. Costigan, G. Crifo, F. Cross, N.J.G. Crosta, M. Crowley, C. Dafonte, C. Damerdji, Y. Dapergolas, A. David, P. David, M. De Cat, P. De Felice, F. De Laverny, P. De Luise, F. De March, R. De Souza, R. Debosscher, J. Del Pozo, E. Delbo, M. Delgado, A. Delgado, H.E. Di Matteo, P. Diakite, S. Distefano, E. Dolding, C. Dos Anjos, S. Drazinos, P. Durán, J. Dzigan, Y. Edvardsson, B. Enke, H. Evans, N.W. Eynard Bontemps, G. Fabre, C. Fabrizio, M. Falcão, A.J. Farràs Casas, M. Federici, L. Fedorets, G. Fernández-Hernández, J. Fernique, P. Fienga, A. Figueras, F. Filippi, F. Findeisen, K. Fonti, A. Fouesneau, M. Fraile, E. Fraser, M. Fuchs, J. Gai, M. Galleti, S. Galluccio, L. Garabato, D. García-Sedano, F. Garralda, N. Gavras, P. Gerssen, J. Geyer, R. Gilmore, G. Girona, S. Giuffrida, G. Gomes, M. González-Marcos, A. González-Núñez, J. González-Vidal, J.J. Granvik, M. Guerrier, A. Guillout, P. Guiraud, J. Gúrpide, A. Gutiérrez-Sánchez, R. Guy, L.P. Haigron, R. Hatzidimitriou, D. Haywood, M. Heiter, U. Helmi, A. Hobbs, D. Hofmann, W. Holl, B. Holland, G. Hunt, J.A.S. Hypki, A. Icardi, V. Irwin, M. Jevardat De Fombelle, G. Jofré, P. Jonker, P.G. Jorissen, A. Julbe, F. Karampelas, A. Kochoska, A. Kohley, R. Kolenberg, K. Kontizas, E. Koposov, S.E. Kordopatis, G. Koubsky, P. Krone-Martins, A. Kudryashova, M. Bachchan, R.K. Lacoste-Seris, F. Lanza, A.F. Lavigne, J.-B. Le Poncin-Lafitte, C. Lebreton, Y. Lebzelter, T. Leccia, S. Leclerc, N. Lecoeur-Taibi, I. Lemaitre, V. Lenhardt, H. Leroux, F. Liao, S. Licata, E. Lindstrøm, H.E.P. Lister, T.A. Livanou, E. Lobel, A. Löffler, W. López, M. Lorenz, D. Macdonald, I. Magalhães Fernandes, T. Managau, S. Mann, R.G. Mantelet, G. Marchal, O. Marchant, J.M. Marinoni, S. Marrese, P.M. Marschalkó, G. Marshall, D.J. Martín-Fleitas, J.M. Martino, M. Mary, N. Matijevič, G. McMillan, P.J. Messina, S. Michalik, D. Millar, N.R. Miranda, B.M.H. Molina, D. Molinaro, M. Molnár, L. Moniez, M. Montegriffo, P. Mor, R. Mora, A. Morbidelli, R. Morel, T. Morgenthaler, S. Morris, D. Mulone, A.F. Narbonne, J. Nelemans, G. Nicastro, L. Noval, L. Ordénovic, C. Ordieres-Meré, J. Osborne, P. Pagani, C. Pagano, I. Pailler, F. Palacin, H. Palaversa, L. Parsons, P. Pecoraro, M. Pedrosa, R. Pentikäinen, H. Pichon, B. Piersimoni, A.M. Pineau, F.-X. Plachy, E. Plum, G. Poujoulet, E. Prša, A. Pulone, L. Ragaini, S. Rago, S. Rambaux, N. Ramos-Lerate, M. Ranalli, P. Rauw, G. Read, A. Regibo, S. Reylé, C. Ribeiro, R.A. Riva, A. Rixon, G. Roelens, M. Romero-Gómez, M. Rowell, N. Royer, F. Ruiz-Dern, L. Sadowski, G. Sagristà Sellés, T. Sahlmann, J. Salgado, J. Salguero, E. Sarasso, M. Savietto, H. Schultheis, M. Sciacca, E. Segol, M. Segovia, J.C. Segransan, D. Shih, I.-C. Smareglia, R. Smart, R.L. Solano, E. Solitro, F. Sordo, R. Soria Nieto, S. Souchay, J. Spagna, A. Spoto, F. Stampa, U. Steele, I.A. Steidelmüller, H. Stephenson, C.A. Stoev, H. Suess, F.F. Süveges, M. Surdej, J. Szegedi-Elek, E. Tapiador, D. Taris, F. Tauran, G. Taylor, M.B. Teixeira, R. Terrett, D. Tingley, B. Trager, S.C. Turon, C. Ulla, A. Utrilla, E. Valentini, G. Van Elteren, A. Van Hemelryck, E. Van Leeuwen, M. Varadi, M. Vecchiato, A. Veljanoski, J. Via, T. Vicente, D. Vogt, S. Voss, H. Votruba, V. Voutsinas, S. Walmsley, G. Weiler, M. Weingrill, K. Wevers, T. Wyrzykowski, L. Yoldas, A. Zerjal, M. Zucker, S. Zurbach, C. Zwitter, T. Alecu, A. Allen, M. Allende Prieto, C. Amorim, A. Anglada-Escudé, G. Arsenijevic, V. Azaz, S. Balm, P. Beck, M. Bernstein, H.-H. Bigot, L. Bijaoui, A. Blasco, C. Bonfigli, M. Bono, G. Boudreault, S. Bressan, A. Brown, S. Brunet, P.-M. Bunclark, P. Buonanno, R. Butkevich, A.G. Carret, C. Carrion, C. Chemin, L. Chéreau, F. Corcione, L. Darmigny, E. De Boer, K.S. De Teodoro, P. De Zeeuw, P.T. Delle Luche, C. Domingues, C.D. Dubath, P. Fodor, F. Frézouls, B. Fries, A. Fustes, D. Fyfe, D. Gallardo, E. Gallegos, J. Gardiol, D. Gebran, M. Gomboc, A. Gómez, A. Grux, E. Gueguen, A. Heyrovsky, A. Hoar, J. Iannicola, G. Isasi Parache, Y. Janotto, A.-M. Joliet, E. Jonckheere, A. Keil, R. Kim, D.-W. Klagyivik, P. Klar, J. Knude, J. Kochukhov, O. Kolka, I. Kos, J. Kutka, A. Lainey, V. Lebouquin, D. Liu, C. Loreggia, D. Makarov, V.V. Marseille, M.G. Martayan, C. Martinez-Rubi, O. Massart, B. Meynadier, F. Mignot, S. Munari, U. Nguyen, A.-T. Nordlander, T. O'Flaherty, K.S. Ocvirk, P. Olias Sanz, A. Ortiz, P. Osorio, J. Oszkiewicz, D. Ouzounis, A. Park, P. Pasquato, E. Peltzer, C. Peralta, J. Péturaud, F. Pieniluoma, T. Pigozzi, E. Poels, J. Prat, G. Prod'Homme, T. Raison, F. Rebordao, J.M. Risquez, D. Rocca-Volmerange, B. Rosen, S. Ruiz-Fuertes, M.I. Russo, F. Serraller Vizcaino, I. Short, A. Siebert, A. Silva, H. Sinachopoulos, D. Slezak, E. Soffel, M. Sosnowska, D. StraizYs, V. Ter Linden, M. Terrell, D. Theil, S. Tiede, C. Troisi, L. Tsalmantza, P. Tur, D. Vaccari, M. Vachier, F. Valles, P. Van Hamme, W. Veltz, L. Virtanen, J. Wallut, J.-M. Wichmann, R. Wilkinson, M.I. Ziaeepour, H. Zschocke, S.

Abstract

Context. Parallaxes for 331 classical Cepheids, 31 Type II Cepheids, and 364 RR Lyrae stars in common between Gaia and the Hipparcos and Tycho-2 catalogues are published in Gaia Data Release 1 (DR1) as part of the Tycho-Gaia Astrometric Solution (TGAS). Aims. In order to test these first parallax measurements of the primary standard candles of the cosmological distance ladder, which involve astrometry collected by Gaia during the initial 14 months of science operation, we compared them with literature estimates and derived new period-luminosity (PL), period-Wesenheit (PW) relations for classical and Type II Cepheids and infrared PL, PL-metallicity (PLZ), and optical luminosity-metallicity (MV-[Fe/H]) relations for the RR Lyrae stars, with zero points based on TGAS. Methods. Classical Cepheids were carefully selected in order to discard known or suspected binary systems. The final sample comprises 102 fundamental mode pulsators with periods ranging from 1.68 to 51.66 days (of which 33 with σΩ/Ω< 0.5). The Type II Cepheids include a total of 26 W Virginis and BL Herculis stars spanning the period range from 1.16 to 30.00 days (of which only 7 with σΩ/Ω< 0.5). The RR Lyrae stars include 200 sources with pulsation period ranging from 0.27 to 0.80 days (of which 112 with σΩ/Ω< 0.5). The new relations were computed using multi-band (V,I,J,Ks) photometry and spectroscopic metal abundances available in the literature, and by applying three alternative approaches: (i) linear least-squares fitting of the absolute magnitudes inferred from direct transformation of the TGAS parallaxes; (ii) adopting astrometry-based luminosities; and (iii) using a Bayesian fitting approach. The last two methods work in parallax space where parallaxes are used directly, thus maintaining symmetrical errors and allowing negative parallaxes to be used. The TGAS-based PL,PW,PLZ, and MV- [Fe/H] relations are discussed by comparing the distance to the Large Magellanic Cloud provided by different types of pulsating stars and alternative fitting methods. Results. Good agreement is found from direct comparison of the parallaxes of RR Lyrae stars for which both TGAS and HST measurements are available. Similarly, very good agreement is found between the TGAS values and the parallaxes inferred from the absolute magnitudes of Cepheids and RR Lyrae stars analysed with the Baade-Wesselink method. TGAS values also compare favourably with the parallaxes inferred by theoretical model fitting of the multi-band light curves for two of the three classical Cepheids and one RR Lyrae star, which were analysed with this technique in our samples. The K-band PL relations show the significant improvement of the TGAS parallaxes for Cepheids and RR Lyrae stars with respect to the Hipparcos measurements. This is particularly true for the RR Lyrae stars for which improvement in quality and statistics is impressive. Conclusions. TGAS parallaxes bring a significant added value to the previous Hipparcos estimates. The relations presented in this paper represent the first Gaia-calibrated relations and form a work-in-progress milestone report in the wait for Gaia-only parallaxes of which a first solution will become available with Gaia Data Release 2 (DR2) in 2018. © ESO, 2017.

Published
2017

16. Testing parallaxes with local Cepheids and RR Lyrae stars

Author

Clementini, G., Eyer, L., Ripepi, V., Marconi, M., Muraveva, T., Garofalo, A., Sarro, L. M., Palmer, M., Luri, X., Molinaro, R., Rimoldini, L., Szabados, L., Musella, I., Anderson, R. I., Prusti, T., De Bruijne, J. H. J., Brown, A. G. A., Vallenari, A., Babusiaux, C., Bailer-Jones, C. A. L., Bastian, U., Biermann, M., Evans, D. W., Jansen, F., Jordi, C., Klioner, S. A., Lammers, U., Lindegren, L., Mignard, F., Panem, C., Pourbaix, D., Randich, S., Sartoretti, P., Siddiqui, H. I., Soubiran, C., Valette, V., Van Leeuwen, F., Walton, N. A., Aerts, C., Arenou, F., Cropper, M., Drimmel, R., Hog, E., Katz, D., Lattanzi, M. G., O'Mullane, W., Grebel, E. K., Holland, A. D., Huc, C., Passot, X., Perryman, M., Bramante, L., Cacciari, C., Castaneda, J., Chaoul, L., Cheek, N., De Angeli, F., Fabricius, C., Guerra, R., Hernandez, J., Jean-Antoine-Piccolo, A., Masana, E., Messineo, R., Mowlavi, N., Nienartowicz, K., Ordonez-Blanco, D., Panuzzo, P., Portell, J., Richards, P. J., Riello, M., Seabroke, G. M., Tanga, P., Thevenin, F., Torra, J., Els, S. G., Gracia-Abril, G., Comoretto, G., Garcia-Reinaldos, M., Lock, T., Mercier, E., Altmann, M., Andrae, R., Astraatmadja, T. L., Bellas-Velidis, I., Benson, K., Berthier, J., Blomme, R., Busso, G., Carry, B., Cellino, A., Cowell, S., Creevey, O., Cuypers, J., Davidson, M., De Ridder, J., De Torres, A., Delchambre, L., Dell'Oro, A., Ducourant, C., Fremat, Y., Garcia-Torres, M., Gosset, E., Halbwachs, J. -L., Hambly, N. C., Harrison, D. L., Hauser, M., Hestroffer, D., Hodgkin, S. T., Huckle, H. E., Hutton, A., Jasniewicz, G., Jordan, S., Kontizas, M., Korn, A. J., Lanzafame, A. C., Manteiga, M., Moitinho, A., Muinonen, K., Osinde, J., Pancino, E., Pauwels, T., Petit, J. -M., Recio-Blanco, A., Robin, A. C., Siopis, C., Smith, M., Smith, K. W., Sozzetti, A., Thuillot, W., Van Reeven, W., Viala, Y., Abbas, U., Abreu Aramburu, A., Accart, S., Aguado, J. J., Allan, P. M., Allasia, W., Altavilla, G., Alvarez, M. A., Alves, J., Andrei, A. H., Anglada Varela, E., Antiche, E., Antojal, T., Anton, S., Arcay, B., Bach, N., Baker, S. G., Balaguer-Nunez, L., Barache, C., Barata, C., Barbier, A., Barblan, F., Barrado Y Navascues, D., Barros, M., Barstow, M. A., Becciani, U., Bellazzini, M., Bello Garcia, A., Belokurov, V., Bendjoya, P., Berihuete, A., Bianchi, L., Bienayme, O., Billebaud, F., Blagorodnova, N., Blanco-Cuaresma, S., Boch, T., Bombrun, A., Borrachero, R., Bouquillon, S., Bourda, G., Bragaglia, A., Breddels, M. A., Brouillet, N., Bruesemeister, T., Bucciarelli, B., Burgess, P., Burgon, R., Burlacu, A., Busonero, D., Buzzi, R., Caffau, E., Cambras, J., Campbell, H., Cancelliere, R., Cantat-Gaudin, T., Carlucci, T., Carrasco, J. M., Castellani, M., Charlot, P., Charnas, J., Chiavassa, A., Clotet, M., Cocozza, G., Collins, R. S., Costigan, G., Crifo, F., Cross, N. J. G., Crosta, M., Crowley, C., Dafonte, C., Damerdji, Y., Dapergolas, A., David, P., David, M., De Cat, P., De Felice, F., De Laverny, P., De Luise, F., De March, R., De Souza, R., Debosscher, J., Del Pozo, E., Delbo, M., Delgado, A., Delgado, H. E., Di Matteo, P., Diakite, S., Distefano, E., Dolding, C., Dos Anjos, S., Drazinos, P., Duran, J., Dzigan, Y., Edvardsson, B., Enke, H., Evans, N. W., Bontemps, G. Eynard, Fabre, C., Fabrizio, M., Falcao, A. J., Farras Casas, M., Federici, L., Fedorets, G., Fernandez-Hernandez, J., Fernique, P., Fienga, A., Figueras, F., Filippi, F., Findeisen, K., Fonti, A., Fouesneau, M., Fraile, E., Fraser, M., Fuchs, J., Gai, M., Galleti, S., Galluccio, L., Garabato, D., Garcia-Sedano, F., Garralda, N., Gavras, P., Gerssen, J., Geyer, R., Gilmore, G., Girona, S., Giuffrida, G., Gomes, M., Gonzalez-Marcos, A., Gonzalez-Nunez, J., Gonzalez-Vidal, J. J., Granvik, M., Guerrier, A., Guillout, P., Guiraud, J., Gurpide, A., Gutierrez-Sanchez, R., Guy, L. P., Haigron, R., Hatzidimitriou, D., Haywood, M., Heiter, U., Helmi, A., Hobbs, D., Hofmann, W., Holl, B., Holland, G., Hunt, J. A. S., Hypki, A., Icardi, V., Irwin, M., De Fombelle, G. Jevardat, Jofre, P., Jonker, P. G., Jorissen, A., Julbe, F., Karampelas, A., Kochoska, A., Kohley, R., Kolenberg, K., Kontizas, E., Koposov, S. E., Kordopatis, G., Koubsky, P., Krone-Martins, A., Kudryashova, M., Bachchan, R. K., Lacoste-Seris, F., Lanza, A. F., Lavigne, J. -B., Le Poncin-Lafitte, C., Lebreton, Y., Lebzelter, T., Leccia, S., Leclerc, N., Lecoeur-Taibi, I., Lemaitre, V., Lenhardt, H., Leroux, F., Liao, S., Licata, E., Lindstrom, H. E. P., Lister, T. A., Livanou, E., Lobel, A., Loeffler, W., Lopez, M., Lorenz, D., Macdonald, I., Magalhaes Fernandes, T., Managau, S., Mann, R. G., Mantelet, G., Marchal, O., Marchant, J. M., Marinoni, S., Marrese, P. M., Marschalko, G., Marsha, D. J., Martin-Fleitas, J. M., Martino, M., Mary, N., Matijevic, G., Mcmillan, P. J., Messina, S., Michalik, D., Millar, N. R., Miranda, B. M. H., Molina, D., Molinaro, M., Molnar, L., Monicz, M., Montegriffo, P., Mor, R., Mora, A., Morbidelli, R., Morel, T., Morgenthaler, S., Morris, D., Mulone, A. F., Narbonne, J., Nelemans, G., Nicastro, L., Noval, L., Ordenovic, C., Ordieres-Mere, J., Osborne, P., Pagani, C., Pagano, I., Pailler, F., Palacin, H., Palaversa, L., Parsons, P., Pecoraro, M., Pedrosa, R., Pentikainen, H., Pichon, B., Piersimoni, A. M., Pineau, F. -X., Plachy, E., Plum, G., Poujoulet, E., Prsa, A., Pulone, L., Ragaini, S., Rago, S., Rambaux, N., Ramos-Lerate, M., Ranalli, P., Rauw, G., Read, A., Regibo, S., Reyle, C., Ribeiro, R. A., Riva, A., Rixon, G., Roelens, M., Romero-Gomez, M., Rowell, N., Royer, F., Ruiz-Dern, L., Sadowski, G., Selles, T. Sagrista, Sahlmann, J., Salgado, J., Salguero, E., Sarasso, M., Savietto, H., Schultheis, M., Sciacca, E., Segol, M., Segovia, J. C., Segransan, D., Shih, I-C., Smareglia, R., Smart, R. L., Solano, E., Solitro, F., Sordo, R., Soria Nieto, S., Souchay, J., Spagna, A., Spoto, F., Stampa, U., Steele, I. A., Steidelmueller, H., Stephenson, C. A., Stoev, H., Suess, F. F., Suveges, M., Surdej, J., Szegedi-Elek, E., Tapiador, D., Taris, F., Tauran, G., Taylor, M. B., Teixeira, R., Terrett, D., Tingley, B., Trager, S. C., Turon, C., Ulla, A., Utrilla, E., Valentini, G., Van Elteren, A., Van Hemelryck, E., Van Leeuwen, M., Varadi, M., Vecchiato, A., Veljanoski, J., Via, T., Vicente, D., Vogt, S., Voss, H., Votruba, V., Voutsinas, S., Walmsley, G., Weiler, M., Weingrill, K., Wevers, T., Wyrzykowski, L., Yoldas, A., Zerjal, M., Zucker, S., Zurbach, C., Zwitter, T., Alecu, A., Allen, M., Allende Prieto, C., Amorim, A., Anglada-Escude, G., Arsenijevic, V., Azaz, S., Balm, P., Beck, M., Bernsteint, H. -H., Bigot, L., Bijaoui, A., Blasco, C., Bonfigli, M., Bono, G., Boudreault, S., Bressan, A., Brown, S., Brunet, P. -M., Bunclark, P., Buonanno, R., Butkevich, A. G., Carret, C., Carrion, C., Chemin, L., Chereau, F., Corcione, L., Darmigny, E., De Boer, K. S., De Teodoro, P., De Zeeuw, P. T., Delle Luche, C., Domingues, C. D., Dubath, P., Fodor, F., Frezouls, B., Fries, A., Fustes, D., Fyfe, D., Gallardo, E., Gallegos, J., Gardiol, D., Gebran, M., Gomboc, A., Gomez, A., Grux, E., Gueguen, A., Heyrovsky, A., Hoar, J., Iannicola, G., Parache, Y. Isasi, Janotto, A. -M., Joliet, E., Jonckheere, A., Keil, R., Kim, D. -W., Klagyivik, P., Klar, J., Knude, J., Kochukhov, O., Kolka, I., Kos, J., Kutka, A., Lainey, V., Lebouquin, D., Liu, C., Loreggia, D., Makarov, V. V., Marseille, M. G., Martayan, C., Martinez-Rubi, O., Massart, B., Meynadier, F., Mignot, S., Munari, U., Nguyen, A. -T., Nordlander, T., O'Flaherty, K. S., Ocvirk, P., Olias Sanz, A., Ortiz, P., Osorio, J., Oszkiewicz, D., Ouzounis, A., Park, P., Pasquato, E., Peltzer, C., Peralta, J., Peturaud, F., Pieniluoma, T., Pigozzi, E., Poels, J., Prat, G., Prod'Homme, T., Raison, F., Rebordao, J. M., Risquez, D., Rocca-Volmerange, B., Rosen, S., Ruiz-Fuertes, M. I., Russo, F., Serraller Vizcaino, I., Short, A., Siebert, A., Silva, H., Sinachopoulos, D., Slezak, E., Soffel, M., Sosnowska, D., Straizys, V., Ter Linden, M., Terrell, D., Theil, S., Tiede, C., Troisi, L., Tsalmantza, P., Tur, D., Vaccari, M., Vachier, F., Valles, P., Van Hamme, W., Veltz, L., Virtanen, J., Wallut, J. -M., Wichmann, R., Wilkinson, M. I., Ziaeepour, H., Zschocke, S., Gaia Collaboration, and Gaia Collaboration

Subjects
stars: variables: RR Lyrae, variables: Cepheids [stars], Astronomi, astrofysik och kosmologi, Physics, parallaxes, distances [stars], data analysis [methods], stars: distances, Astronomy, Astrophysics and Cosmology, astrometry, methods: data analysis, variables: RR Lyrae [stars], stars: variables: Cepheids
Abstract

Context. Parallaxes for 331 classical Cepheids, 31 Type II Cepheids, and 364 RR Lyrae stars in common between Gaia and the HIPPARCOS and Tycho-2 catalogues are published in Gaia Data Release 1 (DR1) as part of the Tycho-Gaia Astrometric Solution (TGAS). Aims. In order to test these first parallax measurements of the primary standard candles of the cosmological distance ladder, which involve astrometry collected by Gaia during the initial 14 months of science operation, we compared them with literature estimates and derived new period-luminosity (PL), period-Wesenheit (PW) relations for classical and Type II Cepheids and infrared PL, PL-metallicity (PLZ), and optical luminosity-metallicity (MV-[Fe/H]) relations for the RR Lyrae stars, with zero points based on TGAS. Methods. Classical Cepheids were carefully selected in order to discard known or suspected binary systems. The final sample comprises 102 fundamental mode pulsators with periods ranging from 1.68 to 51.66 days (of which 33 with sigma(omega)/omega < 0 : 5). The Type II Cepheids include a total of 26 W Virginis and BL Herculis stars spanning the period range from 1.16 to 30.00 days (of which only 7 with sigma(omega)/omega 0 : 5). The RR Lyrae stars include 200 sources with pulsation period ranging from 0.27 to 0.80 days (of which 112 with sigma(omega)/omega < 0 : 5). The new relations were computed using multi- band (V; I; J; K-s) photometry and spectroscopic metal abundances available in the literature, and by applying three alternative approaches: (i) linear least-squares fitting of the absolute magnitudes inferred from direct transformation of the TGAS parallaxes; (ii) adopting astrometry-based luminosities; and (iii) using a Bayesian fitting approach. The last two methods work in parallax space where parallaxes are used directly, thus maintaining symmetrical errors and allowing negative parallaxes to be used. The TGAS-based PL; PW; PLZ, and MV [Fe/H] relations are discussed by comparing the distance to the Large Magellanic Cloud provided by different types of pulsating stars and alternative fitting methods. Results. Good agreement is found from direct comparison of the parallaxes of RR Lyrae stars for which both TGAS and HST measurements are available. Similarly, very good agreement is found between the TGAS values and the parallaxes inferred from the absolute magnitudes of Cepheids and RR Lyrae stars analysed with the Baade-Wesselink method. TGAS values also compare favourably with the parallaxes inferred by theoretical model fitting of the multi-band light curves for two of the three classical Cepheids and one RR Lyrae star, which were analysed with this technique in our samples. The K-band PL relations show the significant improvement of the TGAS parallaxes for Cepheids and RR Lyrae stars with respect to the HIPPARCOS measurements. This is particularly true for the RR Lyrae stars for which improvement in quality and statistics is impressive. Conclusions. TGAS parallaxes bring a significant added value to the previous HIPPARCOS estimates. The relations presented in this paper represent the first Gaia-calibrated relations and form a work-in-progress milestone report in the wait for Gaia-only parallaxes of which a first solution will become available with Gaia Data Release 2 (DR2) in 2018. Acknowledgements. This work has made use of results from the European Space Agency (ESA) space mission Gaia, the data from which were processed by the Gaia Data Processing and Analysis Consortium (DPAC). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. The Gaia mission website is http://www.cosmos.esa.int/gaia. The authors are current or past members of the ESA and Airbus DS Gaia mission teams and of the Gaia DPAC. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France. We thank the referee, Pierre Kervella, for his detailed comments and suggestions that have helped to improve the paper analysis and presentation. This work has financially been supported by: the Agenzia Spaziale Italiana (ASI) through grants I/037/08/0, I/058/10/0, 2014-025-R.0, and 2014-025-R.1.2015 to INAF and contracts I/008/10/0 and 2013/030/I.0 to ALTEC S.p.A.; the Algerian Centre de Recherche en Astronomic, Astrophysique et Geophysique of Bouzareah Observatory; the Austrian FWF Hertha Firnberg Programme through grants T359, P20046, and P23737; the BELgian federal Science Policy Office (BELSPO) through various PROgramme de Developpement d'Experiences scientifiques (PRODEX) grants; the Brazil-France exchange programmes FAPESP-COFECUB and CAPES-COFECUB; the Chinese National Science Foundation through grant NSFC 11573054; the Czech-Republic Ministry of Education, Youth, and Sports through grant LG 15010; the Danish Ministry of Science; the Estonian Ministry of Education and Research through grant IUT40-1; the European Commission's Sixth Framework Programme through the European Leadership in Space Astrometry (ELSA) Marie Curie Research Training Network (MRTN-CT-2006-033481), through Marie Curie project PIOF-GA-2009-255267 (SAS-RRL), and through a Marie Curie Transfer-of-Knowledge (ToK) fellowship (MTKD-CT-2004-014188); the European Commission's Seventh Framework Programme through grant FP7-606740 (FP7-SPACE-2013-1) for the Gaia European Network for Improved data User Services (GENIUS) and through grant 264895 for the Gaia Research for European Astronomy Training (GREAT-ITN) network; the European Research Council (ERC) through grant 320360 and through the European Union's Horizon 2020 research and innovation programme through grant agreement 670519 (Mixing and Angular Momentum tranSport of massIvE stars - MAMSIE); the European Science Foundation (ESF), in the framework of the Gaia Research for European Astronomy Training Research Network Programme (GREAT-ESF); the European Space Agency in the framework of the Gaia project; the European Space Agency Plan for European Cooperating States (PECS) programme through grants for Slovenia; the Czech Space Office through ESA PECS contract 98058; the Academy of Finland; the Magnus Ehrnrooth Foundation; the French Centre National de la Recherche Scientifique (CNRS) through action "Defi MASTODONS"; the French Centre National d'Etudes Spatiales (CNES); the French L'Agence Nationale de la Recherche (ANR) "investissements d'avenir" Initiatives D'EXcellence (IDEX) programme PSL* through grant ANR-10-IDEX-0001-02; the Region Aquitaine; the Universite de Bordeaux; the French Utinam Institute of the Universite de Franche-Comte, supported by the Region de Franche-Comte and the Institut des Sciences de l'Univers (INSU); the German Aerospace Agency (Deutsches Zentrum fur Luft- and Raumfahrt e.V. , DLR) through grants 50QG0501, 50QG0601, 50QG0602, 50QG0701, 50QG0901, 50QG1001, 50QG1101, 50QG140, 50QG1401, 50QG1402, and 50QG1404; the Hungarian Academy of Sciences through Lendulet Programme LP2014-17; the Hungarian National Research, Development, and Innovation Office through grants NKFIH K-115709, K-119517 and PD-116175; the Israel Ministry of Science and Technology through grant 3-9082; the Italian Istituto Nazionale di Astrofisica (INAF); the Netherlands Organisation for Scientific Research (NWO) through grant NWO-M-614.061.414 and through a VICI grant to A. Helmi; the Netherlands Research School for Astronomy (NOVA); the Polish National Science Centre through HARMONIA grant 2015/18/M/ST9/00544; the Portugese Fundacao para a Ciencia e a Tecnologia (FCT) through grants PTDC/CTE-SPA/118692/2010, PDCTE/CTE-AST/81711/2003, and SFRH/BPD/74697/2010; the Strategic Programmes PEst-OE/AMB/UI4006/2011 for SIM, UID/FIS/00099/2013 for CENTRA, and UID/EEA/00066/2013 for UNINOVA; the Slovenian Research Agency; the Spanish Ministry of Economy MINECO-FEDER through grants AyA2014-55216, AyA2011-24052, E5P2013-48318-C2-R, and E5P2014-55996-C2-R and MDM-2014-0369 of ICCUB (Unidad de Excelencia Maria de Maeztu); the Swedish National Space Board (SNSB/Rymdstyrelsen); the Swiss State Secretariat for Education, Research, and Innovation through the ESA PRODEX programme; the Swiss Mesures d'Accompagnement; the Swiss Activites Nationales Complementaires; the Swiss National Science Foundation, including an Early Postdoc.Mobility fellowship; the United Kingdom Rutherford Appleton Laboratory; the United Kingdom Science and Technology Facilities Council (STFC) through grants PP/C506756/1 and ST/100047X/1; and the United Kingdom Space Agency (UKSA) through grants ST/K000578/1 and ST/N000978/1.

Published
2017

17. The GALAH Survey: non-LTE departure coefficients for large spectroscopic surveys.

Author

Amarsi, A. M., Lind, K., Osorio, Y., Nordlander, T., Bergemann, M., Reggiani, H., Wang, E. X., Buder, S., Asplund, M., Barklem, P. S., Wehrhahn, A., Skúladóttir, Á., Kobayashi, C., Karakas, A. I., Gao, X. D., Bland-Hawthorn, J., De Silva, G. M., Kos, J., Lewis, G. F., and Martell, S. L.

Subjects
ALKALINE earth metals, LOCAL thermodynamic equilibrium, BIG data, STELLAR spectra, INELASTIC collisions, ATOMIC models, STELLAR atmospheres
Abstract

Massive sets of stellar spectroscopic observations are rapidly becoming available and these can be used to determine the chemical composition and evolution of the Galaxy with unprecedented precision. One of the major challenges in this endeavour involves constructing realistic models of stellar spectra with which to reliably determine stellar abundances. At present, large stellar surveys commonly use simplified models that assume that the stellar atmospheres are approximately in local thermodynamic equilibrium (LTE). To test and ultimately relax this assumption, we have performed non-LTE calculations for 13 different elements (H, Li, C, N, O, Na, Mg, Al, Si, K, Ca, Mn, and Ba), using recent model atoms that have physically-motivated descriptions for the inelastic collisions with neutral hydrogen, across a grid of 3756 1D MARCS model atmospheres that spans 3000 ≤ Teff∕K ≤ 8000, − 0.5 ≤log g∕cm s−2 ≤ 5.5, and − 5 ≤ [Fe/H] ≤ 1. We present the grids of departure coefficients that have been implemented into the GALAH DR3 analysis pipeline in order to complement the extant non-LTE grid for iron. We also present a detailed line-by-line re-analysis of 50 126 stars from GALAH DR3. We found that relaxing LTE can change the abundances by between − 0.7 dex and + 0.2 dex for different lines and stars. Taking departures from LTE into account can reduce the dispersion in the [A/Fe] versus [Fe/H] plane by up to 0.1 dex, and it can remove spurious differences between the dwarfs and giants by up to 0.2 dex. The resulting abundance slopes can thus be qualitatively different in non-LTE, possibly with important implications for the chemical evolution of our Galaxy. The grids of departure coefficients are publicly available and can be implemented into LTE pipelines to make the most of observational data sets from large spectroscopic surveys. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

18. The Gaia mission

Author

Prusti, T. De Bruijne, J.H.J. Brown, A.G.A. Vallenari, A. Babusiaux, C. Bailer-Jones, C.A.L. Bastian, U. Biermann, M. Evans, D.W. Eyer, L. Jansen, F. Jordi, C. Klioner, S.A. Lammers, U. Lindegren, L. Luri, X. Mignard, F. Milligan, D.J. Panem, C. Poinsignon, V. Pourbaix, D. Randich, S. Sarri, G. Sartoretti, P. Siddiqui, H.I. Soubiran, C. Valette, V. Van Leeuwen, F. Walton, N.A. Aerts, C. Arenou, F. Cropper, M. Drimmel, R. Høg, E. Katz, D. Lattanzi, M.G. O'Mullane, W. Grebel, E.K. Holland, A.D. Huc, C. Passot, X. Bramante, L. Cacciari, C. Castañeda, J. Chaoul, L. Cheek, N. De Angeli, F. Fabricius, C. Guerra, R. Hernández, J. Jean-Antoine-Piccolo, A. Masana, E. Messineo, R. Mowlavi, N. Nienartowicz, K. Ordóñez-Blanco, D. Panuzzo, P. Portell, J. Richards, P.J. Riello, M. Seabroke, G.M. Tanga, P. Thévenin, F. Torra, J. Els, S.G. Gracia-Abril, G. Comoretto, G. Garcia-Reinaldos, M. Lock, T. Mercier, E. Altmann, M. Andrae, R. Astraatmadja, T.L. Bellas-Velidis, I. Benson, K. Berthier, J. Blomme, R. Busso, G. Carry, B. Cellino, A. Clementini, G. Cowell, S. Creevey, O. Cuypers, J. Davidson, M. De Ridder, J. De Torres, A. Delchambre, L. Dell'Oro, A. Ducourant, C. Frémat, Y. García-Torres, M. Gosset, E. Halbwachs, J.-L. Hambly, N.C. Harrison, D.L. Hauser, M. Hestroffer, D. Hodgkin, S.T. Huckle, H.E. Hutton, A. Jasniewicz, G. Jordan, S. Kontizas, M. Korn, A.J. Lanzafame, A.C. Manteiga, M. Moitinho, A. Muinonen, K. Osinde, J. Pancino, E. Pauwels, T. Petit, J.-M. Recio-Blanco, A. Robin, A.C. Sarro, L.M. Siopis, C. Smith, M. Smith, K.W. Sozzetti, A. Thuillot, W. Van Reeven, W. Viala, Y. Abbas, U. Abreu Aramburu, A. Accart, S. Aguado, J.J. Allan, P.M. Allasia, W. Altavilla, G. Álvarez, M.A. Alves, J. Anderson, R.I. Andrei, A.H. Anglada Varela, E. Antiche, E. Antoja, T. Antón, S. Arcay, B. Atzei, A. Ayache, L. Bach, N. Baker, S.G. Balaguer-Núñez, L. Barache, C. Barata, C. Barbier, A. Barblan, F. Baroni, M. Barrado Y Navascués, D. Barros, M. Barstow, M.A. Becciani, U. Bellazzini, M. Bellei, G. Bello García, A. Belokurov, V. Bendjoya, P. Berihuete, A. Bianchi, L. Bienaymé, O. Billebaud, F. Blagorodnova, N. Blanco-Cuaresma, S. Boch, T. Bombrun, A. Borrachero, R. Bouquillon, S. Bourda, G. Bouy, H. Bragaglia, A. Breddels, M.A. Brouillet, N. Brüsemeister, T. Bucciarelli, B. Budnik, F. Burgess, P. Burgon, R. Burlacu, A. Busonero, D. Buzzi, R. Caffau, E. Cambras, J. Campbell, H. Cancelliere, R. Cantat-Gaudin, T. Carlucci, T. Carrasco, J.M. Castellani, M. Charlot, P. Charnas, J. Charvet, P. Chassat, F. Chiavassa, A. Clotet, M. Cocozza, G. Collins, R.S. Collins, P. Costigan, G. Crifo, F. Cross, N.J.G. Crosta, M. Crowley, C. Dafonte, C. Damerdji, Y. Dapergolas, A. David, P. David, M. De Cat, P. De Felice, F. De Laverny, P. De Luise, F. De March, R. De Martino, D. De Souza, R. Debosscher, J. Del Pozo, E. Delbo, M. Delgado, A. Delgado, H.E. Di Marco, F. Di Matteo, P. Diakite, S. Distefano, E. Dolding, C. Dos Anjos, S. Drazinos, P. Durán, J. Dzigan, Y. Ecale, E. Edvardsson, B. Enke, H. Erdmann, M. Escolar, D. Espina, M. Evans, N.W. Eynard Bontemps, G. Fabre, C. Fabrizio, M. Faigler, S. Falcão, A.J. Farràs Casas, M. Faye, F. Federici, L. Fedorets, G. Fernández-Hernández, J. Fernique, P. Fienga, A. Figueras, F. Filippi, F. Findeisen, K. Fonti, A. Fouesneau, M. Fraile, E. Fraser, M. Fuchs, J. Furnell, R. Gai, M. Galleti, S. Galluccio, L. Garabato, D. García-Sedano, F. Garé, P. Garofalo, A. Garralda, N. Gavras, P. Gerssen, J. Geyer, R. Gilmore, G. Girona, S. Giuffrida, G. Gomes, M. González-Marcos, A. González-Núñez, J. González-Vidal, J.J. Granvik, M. Guerrier, A. Guillout, P. Guiraud, J. Gúrpide, A. Gutiérrez-Sánchez, R. Guy, L.P. Haigron, R. Hatzidimitriou, D. Haywood, M. Heiter, U. Helmi, A. Hobbs, D. Hofmann, W. Holl, B. Holland, G. Hunt, J.A.S. Hypki, A. Icardi, V. Irwin, M. Jevardat De Fombelle, G. Jofré, P. Jonker, P.G. Jorissen, A. Julbe, F. Karampelas, A. Kochoska, A. Kohley, R. Kolenberg, K. Kontizas, E. Koposov, S.E. Kordopatis, G. Koubsky, P. Kowalczyk, A. Krone-Martins, A. Kudryashova, M. Kull, I. Bachchan, R.K. Lacoste-Seris, F. Lanza, A.F. Lavigne, J.-B. Le Poncin-Lafitte, C. Lebreton, Y. Lebzelter, T. Leccia, S. Leclerc, N. Lecoeur-Taibi, I. Lemaitre, V. Lenhardt, H. Leroux, F. Liao, S. Licata, E. Lindstrøm, H.E.P. Lister, T.A. Livanou, E. Lobel, A. Löffler, W. López, M. Lopez-Lozano, A. Lorenz, D. Loureiro, T. MacDonald, I. Magalhães Fernandes, T. Managau, S. Mann, R.G. Mantelet, G. Marchal, O. Marchant, J.M. Marconi, M. Marie, J. Marinoni, S. Marrese, P.M. Marschalkó, G. Marshall, D.J. Martín-Fleitas, J.M. Martino, M. Mary, N. Matijevič, G. Mazeh, T. McMillan, P.J. Messina, S. Mestre, A. Michalik, D. Millar, N.R. Miranda, B.M.H. Molina, D. Molinaro, R. Molinaro, M. Molnár, L. Moniez, M. Montegriffo, P. Monteiro, D. Mor, R. Mora, A. Morbidelli, R. Morel, T. Morgenthaler, S. Morley, T. Morris, D. Mulone, A.F. Muraveva, T. Musella, I. Narbonne, J. Nelemans, G. Nicastro, L. Noval, L. Ordénovic, C. Ordieres-Meré, J. Osborne, P. Pagani, C. Pagano, I. Pailler, F. Palacin, H. Palaversa, L. Parsons, P. Paulsen, T. Pecoraro, M. Pedrosa, R. Pentikäinen, H. Pereira, J. Pichon, B. Piersimoni, A.M. Pineau, F.-X. Plachy, E. Plum, G. Poujoulet, E. Prša, A. Pulone, L. Ragaini, S. Rago, S. Rambaux, N. Ramos-Lerate, M. Ranalli, P. Rauw, G. Read, A. Regibo, S. Renk, F. Reylé, C. Ribeiro, R.A. Rimoldini, L. Ripepi, V. Riva, A. Rixon, G. Roelens, M. Romero-Gómez, M. Rowell, N. Royer, F. Rudolph, A. Ruiz-Dern, L. Sadowski, G. Sagristà Sellés, T. Sahlmann, J. Salgado, J. Salguero, E. Sarasso, M. Savietto, H. Schnorhk, A. Schultheis, M. Sciacca, E. Segol, M. Segovia, J.C. Segransan, D. Serpell, E. Shih, I.-C. Smareglia, R. Smart, R.L. Smith, C. Solano, E. Solitro, F. Sordo, R. Soria Nieto, S. Souchay, J. Spagna, A. Spoto, F. Stampa, U. Steele, I.A. Steidelmüller, H. Stephenson, C.A. Stoev, H. Suess, F.F. Süveges, M. Surdej, J. Szabados, L. Szegedi-Elek, E. Tapiador, D. Taris, F. Tauran, G. Taylor, M.B. Teixeira, R. Terrett, D. Tingley, B. Trager, S.C. Turon, C. Ulla, A. Utrilla, E. Valentini, G. Van Elteren, A. Van Hemelryck, E. Van Leeuwen, M. Varadi, M. Vecchiato, A. Veljanoski, J. Via, T. Vicente, D. Vogt, S. Voss, H. Votruba, V. Voutsinas, S. Walmsley, G. Weiler, M. Weingrill, K. Werner, D. Wevers, T. Whitehead, G. Wyrzykowski, Ł. Yoldas, A. Žerjal, M. Zucker, S. Zurbach, C. Zwitter, T. Alecu, A. Allen, M. Allende Prieto, C. Amorim, A. Anglada-Escudé, G. Arsenijevic, V. Azaz, S. Balm, P. Beck, M. Bernstein, H.-H. Bigot, L. Bijaoui, A. Blasco, C. Bonfigli, M. Bono, G. Boudreault, S. Bressan, A. Brown, S. Brunet, P.-M. Bunclark, P. Buonanno, R. Butkevich, A.G. Carret, C. Carrion, C. Chemin, L. Chéreau, F. Corcione, L. Darmigny, E. De Boer, K.S. De Teodoro, P. De Zeeuw, P.T. Delle Luche, C. Domingues, C.D. Dubath, P. Fodor, F. Frézouls, B. Fries, A. Fustes, D. Fyfe, D. Gallardo, E. Gallegos, J. Gardiol, D. Gebran, M. Gomboc, A. Gómez, A. Grux, E. Gueguen, A. Heyrovsky, A. Hoar, J. Iannicola, G. Isasi Parache, Y. Janotto, A.-M. Joliet, E. Jonckheere, A. Keil, R. Kim, D.-W. Klagyivik, P. Klar, J. Knude, J. Kochukhov, O. Kolka, I. Kos, J. Kutka, A. Lainey, V. Lebouquin, D. Liu, C. Loreggia, D. Makarov, V.V. Marseille, M.G. Martayan, C. Martinez-Rubi, O. Massart, B. Meynadier, F. Mignot, S. Munari, U. Nguyen, A.-T. Nordlander, T. Ocvirk, P. O'Flaherty, K.S. Olias Sanz, A. Ortiz, P. Osorio, J. Oszkiewicz, D. Ouzounis, A. Palmer, M. Park, P. Pasquato, E. Peltzer, C. Peralta, J. Péturaud, F. Pieniluoma, T. Pigozzi, E. Poels, J. Prat, G. Prod'homme, T. Raison, F. Rebordao, J.M. Risquez, D. Rocca-Volmerange, B. Rosen, S. Ruiz-Fuertes, M.I. Russo, F. Sembay, S. Serraller Vizcaino, I. Short, A. Siebert, A. Silva, H. Sinachopoulos, D. Slezak, E. Soffel, M. Sosnowska, D. Straižys, V. Ter Linden, M. Terrell, D. Theil, S. Tiede, C. Troisi, L. Tsalmantza, P. Tur, D. Vaccari, M. Vachier, F. Valles, P. Van Hamme, W. Veltz, L. Virtanen, J. Wallut, J.-M. Wichmann, R. Wilkinson, M.I. Ziaeepour, H. Zschocke, S.

Subjects
instruments [space vehicles], proper motions, parallaxes, astrometry, telescopes, structure [Galaxy]
Abstract

Gaia is a cornerstone mission in the science programme of the European Space Agency (ESA). The spacecraft construction was approved in 2006, following a study in which the original interferometric concept was changed to a direct-imaging approach. Both the spacecraft and the payload were built by European industry. The involvement of the scientific community focusses on data processing for which the international Gaia Data Processing and Analysis Consortium (DPAC) was selected in 2007. Gaia was launched on 19 December 2013 and arrived at its operating point, the second Lagrange point of the Sun-Earth-Moon system, a few weeks later. The commissioning of the spacecraft and payload was completed on 19 July 2014. The nominal five-year mission started with four weeks of special, ecliptic-pole scanning and subsequently transferred into full-sky scanning mode. We recall the scientific goals of Gaia and give a description of the as-built spacecraft that is currently (mid-2016) being operated to achieve these goals. We pay special attention to the payload module, the performance of which is closely related to the scientific performance of the mission. We provide a summary of the commissioning activities and findings, followed by a description of the routine operational mode. We summarise scientific performance estimates on the basis of in-orbit operations. Several intermediate Gaia data releases are planned and the data can be retrieved from the Gaia Archive, which is available through the Gaia home page.http://www.cosmos.esa.int/gaia

Published
2016
Full Text
View/download PDF

19. Gaia Data Release 1

Author

Brown, A., Vallenari, A., Prusti, T., de Bruijne, J. H.J., Mignard, F., Drimmel, R., Babusiaux, C., Bailer-Jones, C. A.L., Bastian, U., Biermann, M., Evans, D., Eyer, L., Jansen, F., Jordi, C., Katz, D., Klioner, S., Lammers, U., Lindegren, L., Luri, X., O’mullane, W., Panem, C., Pourbaix, D., Randich, S., Sartoretti, P., Siddiqui, H., Soubiran, C., Valette, V., van Leeuwen, F., Walton, N., Aerts, C., Arenou, F., Cropper, M., Høg, E., Lattanzi, M., Grebel, E., Holland, A., Huc, C., Passot, X., Perryman, M., Bramante, L., Cacciari, C., Castañeda, J., Chaoul, L., Cheek, N., de Angeli, F., Fabricius, C., Guerra, R., Hernández, J., Jean-Antoine-Piccolo, A., Masana, E., Messineo, R., Mowlavi, N., Nienartowicz, K., Ordóñez-Blanco, D., Panuzzo, P., Portell, J., Richards, P., Riello, M., Seabroke, G., Tanga, P., Thévenin, F., Torra, J., Els, S., Gracia-Abril, G., Comoretto, G., Garcia-Reinaldos, M., Lock, T., Mercier, E., Altmann, M., Andrae, R., Astraatmadja, T., Bellas-Velidis, I., Benson, K., Berthier, J., Blomme, R., Busso, G., Carry, B., Cellino, A., Clementini, G., Cowell, S., Creevey, O., Cuypers, J., Davidson, M., de Ridder, J., de Torres, A., Delchambre, L., Dell’oro, A., Ducourant, C., Frémat, Y., García-Torres, M., Gosset, E., Halbwachs, J.-L., Hambly, N., Harrison, D., Hauser, M., Hestroffer, D., Hodgkin, S., Huckle, H., Hutton, A., Jasniewicz, G., Jordan, S., Kontizas, M., Korn, A., Lanzafame, A., Manteiga, M., Moitinho, A., Muinonen, K., Osinde, J., Pancino, E., Pauwels, T., Petit, Jean-Marc, Recio-Blanco, A., Robin, Annie C., Sarro, L., Siopis, C., Smith, M., Smith, K., Sozzetti, A., Thuillot, W., van Reeven, W., Viala, Y., Abbas, U., Abreu Aramburu, A., Accart, S., Aguado, J., Allan, P., Allasia, W., Altavilla, G., Álvarez, M., Alves, J., Anderson, R., Andrei, A., Anglada Varela, E., Antiche, E., Antoja, T., Antón, S., Arcay, B., Bach, N., Baker, S., Balaguer-Núñez, L., Barache, C., Barata, C., Barbier, A., Barblan, F., Barrado y Navascués, D., Barros, M., Barstow, M., Becciani, U., Bellazzini, M., Bello García, A., Belokurov, V., Bendjoya, P., Berihuete, A., Bianchi, L., Bienaymé, O., Billebaud, F., Blagorodnova, N., Blanco-Cuaresma, S., Boch, T., Bombrun, A., Borrachero, R., Bouquillon, S., Bourda, G., Bouy, H., Bragaglia, A., Breddels, M., Brouillet, N., Brüsemeister, T., Bucciarelli, B., Burgess, P., Burgon, R., Burlacu, A., Busonero, D., Buzzi, R., Caffau, E., Cambras, J., Campbell, H., Cancelliere, R., Cantat-Gaudin, T., Carlucci, T., Carrasco, J., Castellani, M., Charlot, P., Charnas, J., Chiavassa, A., Clotet, M., Cocozza, G., Collins, R., Costigan, G., Crifo, F., Cross, N. J.G., Crosta, M., Crowley, C., Dafonte, C., Damerdji, Y., Dapergolas, A., David, P., David, M., de Cat, P., de Felice, F., de Laverny, P., de Luise, F., de March, R., de Martino, D., de Souza, R., Debosscher, J., del Pozo, E., Delbo, M., Delgado, A., Delgado, H., Di Matteo, P., Diakite, S., Distefano, E., Dolding, C., dos Anjos, S., Drazinos, P., Duran, J., Dzigan, Y., Edvardsson, B., Enke, H., Evans, N., Eynard Bontemps, G., Fabre, C., Fabrizio, M., Faigler, S., Falcão, A., Farràs Casas, M., Federici, L., Fedorets, G., Fernández-Hernández, J., Fernique, P., Fienga, A., Figueras, F., Filippi, F., Findeisen, K., Fonti, A., Fouesneau, M., Fraile, E., Fraser, M., Fuchs, J., Gai, M., Galleti, S., Galluccio, L., Garabato, D., García-Sedano, F., Garofalo, A., Garralda, N., Gavras, P., Gerssen, J., Geyer, R., Gilmore, G., Girona, S., Giuffrida, G., Gomes, M., González-Marcos, A., González-Núñez, J., González-Vidal, J., Granvik, M., Guerrier, A., Guillout, P., Guiraud, J., Gúrpide, A., Gutiérrez-Sánchez, R., Guy, L., Haigron, R., Hatzidimitriou, D., Haywood, M., Heiter, U., Helmi, A., Hobbs, D., Hofmann, W., Holl, B., Holland, G., Hunt, J. A.S., Hypki, A., Icardi, V., Irwin, M., Jevardat de Fombelle, G., Jofré, P., Jonker, P., Jorissen, A., Julbe, F., Karampelas, A., Kochoska, A., Kohley, R., Kolenberg, K., Kontizas, E., Koposov, S., Kordopatis, G., Koubsky, P., Krone-Martins, A., Kudryashova, M., Kull, I., Bachchan, R., Lacoste-Seris, F., Lanza, A., Lavigne, J.-B., Le Poncin-Lafitte, C., Lebreton, Y., Lebzelter, T., Leccia, S., Leclerc, N., Lecoeur-Taibi, I., Lemaitre, V., Lenhardt, H., Leroux, F., Liao, S., Licata, E., Lindstrøm, H. E.P., Lister, T., Livanou, E., Lobel, A., Löffler, W., López, M., Lorenz, D., Macdonald, I., Magalhães Fernandes, T., Managau, S., Mann, R., Mantelet, G., Marchal, O., Marchant, J., Marconi, M., Marinoni, S., Marrese, P., Marschalkó, G., Marshall, D., Martín-Fleitas, J., Martino, M., Mary, N., Matijevič, G., Mazeh, T., Mcmillan, P., Messina, S., Michalik, D., Millar, N., Miranda, B., Molina, D., Molinaro, R., Molinaro, M., Molnár, L., Moniez, M., Montegriffo, P., Mor, R., Mora, A., Morbidelli, R., Morel, T., Morgenthaler, S., Morris, D., Mulone, A., Muraveva, T., Musella, I., Narbonne, J., Nelemans, G., Nicastro, L., Noval, L., Ordénovic, C., Ordieres-Meré, J., Osborne, P., Pagani, C., Pagano, I., Pailler, F., Palacin, H., Palaversa, L., Parsons, P., Pecoraro, M., Pedrosa, R., Pentikäinen, H., Pichon, B., Piersimoni, A., Pineau, F.-X., Plachy, E., Plum, G., Poujoulet, E., Prša, A., Pulone, L., Ragaini, S., Rago, S., Rambaux, N., Ramos-Lerate, M., Ranalli, P., Rauw, G., Read, A., Regibo, S., Reylé, C., Ribeiro, R., Rimoldini, L., Ripepi, V., Riva, A., Rixon, G., Roelens, M., Romero-Gómez, M., Rowell, N., Royer, F., Ruiz-Dern, L., Sadowski, G., Sagristà Sellés, T., Sahlmann, J., Salgado, J., Salguero, E., Sarasso, M., Savietto, H., Schultheis, M., Sciacca, E., Segol, M., Segovia, J., Segransan, D., Shih, I.-C., Smareglia, R., Smart, R., Solano, E., Solitro, F., Sordo, R., Soria Nieto, S., Souchay, J., Spagna, A., Spoto, F., Stampa, U., Steele, I., Steidelmüller, H., Stephenson, C., Stoev, H., Suess, F., Süveges, M., Surdej, J., Szabados, L., Szegedi-Elek, E., Tapiador, D., Taris, F., Tauran, G., Taylor, M., Teixeira, R., Terrett, D., Tingley, B., Trager, S., Turon, C., Ulla, A., Utrilla, E., Valentini, G., van Elteren, A., van Hemelryck, E., van Leeuwen, M., Varadi, M., Vecchiato, A., Veljanoski, J., Via, T., Vicente, D., Vogt, S., Voss, H., Votruba, V., Voutsinas, S., Walmsley, G., Weiler, M., Weingrill, K., Wevers, T., Wyrzykowski, Ł., Yoldas, A., Žerjal, M., Zucker, S., Zurbach, C., Zwitter, T., Alecu, A., Allen, M., Allende Prieto, C., Amorim, A., Anglada-Escudé, G., Arsenijevic, V., Azaz, S., Balm, P., Beck, M., Bernstein, H.-H., Bigot, L., Bijaoui, A., Blasco, C., Bonfigli, M., Bono, G., Boudreault, S., Bressan, A., Brown, S., Brunet, P.-M., Bunclark, P., Buonanno, R., Butkevich, A., Carret, C., Carrion, C., Chemin, L., Chéreau, F., Corcione, L., Darmigny, E., de Boer, K., de Teodoro, P., de Zeeuw, P., Delle Luche, C., Domingues, C., Dubath, P., Fodor, F., Frézouls, B., Fries, A., Fustes, D., Fyfe, D., Gallardo, E., Gallegos, J., Gardiol, D., Gebran, M., Gomboc, A., Gómez, A., Grux, E., Gueguen, A., Heyrovsky, A., Hoar, J., Iannicola, G., Isasi Parache, Y., Janotto, A.-M., Joliet, E., Jonckheere, A., Keil, R., Kim, D.-W., Klagyivik, P., Klar, J., Knude, J., Kochukhov, O., Kolka, I., Kos, J., Kutka, A., Lainey, V., Lebouquin, D., Liu, C., Loreggia, D., Makarov, V., Marseille, M., Martayan, C., Martinez-Rubi, O., Massart, B., Meynadier, F., Mignot, S., Munari, U., Nguyen, A.-T., Nordlander, T., Ocvirk, P., O’flaherty, K., Olias Sanz, A., Ortiz, P., Osorio, J., Oszkiewicz, D., Ouzounis, A., Palmer, M., Park, P., Pasquato, E., Peltzer, C., Peralta, J., Péturaud, F., Pieniluoma, T., Pigozzi, E., Poels, J., Prat, G., Prod’homme, T., Raison, F., Rebordao, J., Risquez, D., Rocca-Volmerange, B., Rosen, S., Ruiz-Fuertes, M., Russo, F., Sembay, S., Serraller Vizcaino, I., Short, A., Siebert, A., Silva, H., Sinachopoulos, D., Slezak, E., Soffel, M., Sosnowska, D., Straižys, V., ter Linden, M., Terrell, D., Theil, S., Tiede, C., Troisi, L., Tsalmantza, P., Tur, D., Vaccari, M., Vachier, F., Valles, P., van Hamme, W., Veltz, L., Virtanen, J., Wallut, J.-M., Wichmann, R., Wilkinson, M., Ziaeepour, H., Zschocke, S., Leiden Observatory [Leiden], Universiteit Leiden, INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), ESA Scientific Support Office, Agence Spatiale Européenne = European Space Agency (ESA), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Torino (OATo), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Astronomy (MPIA), Astronomische Rechen-Institut [Heidelberg] (ARI), Zentrum für Astronomie der Universität Heidelberg (ZAH), Universität Heidelberg [Heidelberg] = Heidelberg University-Universität Heidelberg [Heidelberg] = Heidelberg University, Institut de Ciencies del Cosmos (ICCUB), Universitat de Barcelona (UB), Institut d'Astronomie et d'Astrophysique [Bruxelles] (IAA), Université libre de Bruxelles (ULB), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES), Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève = University of Geneva (UNIGE), Thales Services, THALES [France], Systèmes de Référence Temps Espace (SYRTE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Astrophysics Research Institute [Liverpool] (ARI), Liverpool John Moores University (LJMU), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), University of Leicester, Konkoly Observatory, Research Centre for Astronomy and Earth Sciences [Budapest], Hungarian Academy of Sciences (MTA)-Hungarian Academy of Sciences (MTA), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Royal Observatory of Belgium [Brussels] (ROB), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Leibniz Institute for Astrophysics Potsdam (AIP)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2016
Full Text
View/download PDF

20. The Gaia -ESO Survey: Sodium and aluminium abundances in giants and dwarfs

Author

Smiljanic, R., Romano, D., Bragaglia, A., Donati, P., Magrini, L., Friel, E., Jacobson, H., Randich, S., Ventura, P., Lind, K., Bergemann, M., Nordlander, T., Morel, T., Pancino, E., Tautvaišienė, G., Adibekyan, V., Tosi, M., Vallenari, A., Gilmore, G., Bensby, T., François, P., Koposov, S., Lanzafame, A., Recio-Blanco, A., Bayo, A., Carraro, G., Casey, A., Costado, M., Franciosini, E., Heiter, U., Hill, V., Hourihane, A., Jofre, P., Lardo, C., De Laverny, P., Lewis, J., Monaco, L., Morbidelli, L., Sacco, G., Sbordone, L., Sousa, S., Worley, C., Zaggia, S., INAF - Osservatorio Astronomico di Bologna (OABO), Istituto Nazionale di Astrofisica (INAF), Institut national de recherche et de sécurité (Vandoeuvre lès Nancy) (INRS ( Vandoeuvre lès Nancy)), INAF - Osservatorio Astrofisico di Arcetri (OAA), Max-Planck-Institut für Astrophysik (MPA), Max-Planck-Gesellschaft, Department of Physics and Astronomy [Uppsala], Uppsala University, Centro de Astrofísica da Universidade do Porto (CAUP), Universidade do Porto, Laboratoire d'astrophysique de l'observatoire de Besançon (UMR 6091) (LAOB), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Institute of Astronomy [Cambridge], University of Cambridge [UK] (CAM), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Catania (OACT), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Ecole Polytechnique Fédérale de Lausanne (EPFL), Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Istituto Nazionale di Fisica Nucleare, Sezione di Milano (INFN), Istituto Nazionale di Fisica Nucleare (INFN), European Southern Observatory [Santiago] (ESO), and European Southern Observatory (ESO)

Subjects
[PHYS]Physics [physics], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2016
Full Text
View/download PDF

21. Gaia Data Release 1: Summary of the astrometric, photometric, and survey properties

Author

Brown, A.G.A. Vallenari, A. Prusti, T. De Bruijne, J.H.J. Mignard, F. Drimmel, R. Babusiaux, C. Bailer-Jones, C.A.L. Bastian, U. Biermann, M. Evans, D.W. Eyer, L. Jansen, F. Jordi, C. Katz, D. Klioner, S.A. Lammers, U. Lindegren, L. Luri, X. O'Mullane, W. Panem, C. Pourbaix, D. Randich, S. Sartoretti, P. Siddiqui, H.I. Soubiran, C. Valette, V. Van Leeuwen, F. Walton, N.A. Aerts, C. Arenou, F. Cropper, M. Høg, E. Lattanzi, M.G. Grebel, E.K. Holland, A.D. Huc, C. Passot, X. Perryman, M. Bramante, L. Cacciari, C. Castañeda, J. Chaoul, L. Cheek, N. De Angeli, F. Fabricius, C. Guerra, R. Hernández, J. Jean-Antoine-Piccolo, A. Masana, E. Messineo, R. Mowlavi, N. Nienartowicz, K. Ordóñez-Blanco, D. Panuzzo, P. Portell, J. Richards, P.J. Riello, M. Seabroke, G.M. Tanga, P. Thévenin, F. Torra, J. Els, S.G. Gracia-Abril, G. Comoretto, G. Garcia-Reinaldos, M. Lock, T. Mercier, E. Altmann, M. Andrae, R. Astraatmadja, T.L. Bellas-Velidis, I. Benson, K. Berthier, J. Blomme, R. Busso, G. Carry, B. Cellino, A. Clementini, G. Cowell, S. Creevey, O. Cuypers, J. Davidson, M. De Ridder, J. De Torres, A. Delchambre, L. Dell'Oro, A. Ducourant, C. Frémat, Y. García-Torres, M. Gosset, E. Halbwachs, J.-L. Hambly, N.C. Harrison, D.L. Hauser, M. Hestroffer, D. Hodgkin, S.T. Huckle, H.E. Hutton, A. Jasniewicz, G. Jordan, S. Kontizas, M. Korn, A.J. Lanzafame, A.C. Manteiga, M. Moitinho, A. Muinonen, K. Osinde, J. Pancino, E. Pauwels, T. Petit, J.-M. Recio-Blanco, A. Robin, A.C. Sarro, L.M. Siopis, C. Smith, M. Smith, K.W. Sozzetti, A. Thuillot, W. Van Reeven, W. Viala, Y. Abbas, U. Abreu Aramburu, A. Accart, S. Aguado, J.J. Allan, P.M. Allasia, W. Altavilla, G. Álvarez, M.A. Alves, J. Anderson, R.I. Andrei, A.H. Anglada Varela, E. Antiche, E. Antoja, T. Antón, S. Arcay, B. Bach, N. Baker, S.G. Balaguer-Núñez, L. Barache, C. Barata, C. Barbier, A. Barblan, F. Barrado Y Navascués, D. Barros, M. Barstow, M.A. Becciani, U. Bellazzini, M. Bello García, A. Belokurov, V. Bendjoya, P. Berihuete, A. Bianchi, L. Bienaymé, O. Billebaud, F. Blagorodnova, N. Blanco-Cuaresma, S. Boch, T. Bombrun, A. Borrachero, R. Bouquillon, S. Bourda, G. Bouy, H. Bragaglia, A. Breddels, M.A. Brouillet, N. Brüsemeister, T. Bucciarelli, B. Burgess, P. Burgon, R. Burlacu, A. Busonero, D. Buzzi, R. Caffau, E. Cambras, J. Campbell, H. Cancelliere, R. Cantat-Gaudin, T. Carlucci, T. Carrasco, J.M. Castellani, M. Charlot, P. Charnas, J. Chiavassa, A. Clotet, M. Cocozza, G. Collins, R.S. Costigan, G. Crifo, F. Cross, N.J.G. Crosta, M. Crowley, C. Dafonte, C. Damerdji, Y. Dapergolas, A. David, P. David, M. De Cat, P. De Felice, F. De Laverny, P. De Luise, F. De March, R. De Martino, D. De Souza, R. Debosscher, J. Del Pozo, E. Delbo, M. Delgado, A. Delgado, H.E. Di Matteo, P. Diakite, S. Distefano, E. Dolding, C. Dos Anjos, S. Drazinos, P. Duran, J. Dzigan, Y. Edvardsson, B. Enke, H. Evans, N.W. Eynard Bontemps, G. Fabre, C. Fabrizio, M. Faigler, S. Falcão, A.J. Farràs Casas, M. Federici, L. Fedorets, G. Fernández-Hernández, J. Fernique, P. Fienga, A. Figueras, F. Filippi, F. Findeisen, K. Fonti, A. Fouesneau, M. Fraile, E. Fraser, M. Fuchs, J. Gai, M. Galleti, S. Galluccio, L. Garabato, D. García-Sedano, F. Garofalo, A. Garralda, N. Gavras, P. Gerssen, J. Geyer, R. Gilmore, G. Girona, S. Giuffrida, G. Gomes, M. González-Marcos, A. González-Núñez, J. González-Vidal, J.J. Granvik, M. Guerrier, A. Guillout, P. Guiraud, J. Gúrpide, A. Gutiérrez-Sánchez, R. Guy, L.P. Haigron, R. Hatzidimitriou, D. Haywood, M. Heiter, U. Helmi, A. Hobbs, D. Hofmann, W. Holl, B. Holland, G. Hunt, J.A.S. Hypki, A. Icardi, V. Irwin, M. Jevardat De Fombelle, G. Jofré, P. Jonker, P.G. Jorissen, A. Julbe, F. Karampelas, A. Kochoska, A. Kohley, R. Kolenberg, K. Kontizas, E. Koposov, S.E. Kordopatis, G. Koubsky, P. Krone-Martins, A. Kudryashova, M. Kull, I. Bachchan, R.K. Lacoste-Seris, F. Lanza, A.F. Lavigne, J.-B. Le Poncin-Lafitte, C. Lebreton, Y. Lebzelter, T. Leccia, S. Leclerc, N. Lecoeur-Taibi, I. Lemaitre, V. Lenhardt, H. Leroux, F. Liao, S. Licata, E. Lindstrøm, H.E.P. Lister, T.A. Livanou, E. Lobel, A. Löffler, W. López, M. Lorenz, D. MacDonald, I. Magalhães Fernandes, T. Managau, S. Mann, R.G. Mantelet, G. Marchal, O. Marchant, J.M. Marconi, M. Marinoni, S. Marrese, P.M. Marschalkó, G. Marshall, D.J. Martín-Fleitas, J.M. Martino, M. Mary, N. Matijevič, G. Mazeh, T. McMillan, P.J. Messina, S. Michalik, D. Millar, N.R. Miranda, B.M.H. Molina, D. Molinaro, R. Molinaro, M. Molnár, L. Moniez, M. Montegriffo, P. Mor, R. Mora, A. Morbidelli, R. Morel, T. Morgenthaler, S. Morris, D. Mulone, A.F. Muraveva, T. Musella, I. Narbonne, J. Nelemans, G. Nicastro, L. Noval, L. Ordénovic, C. Ordieres-Meré, J. Osborne, P. Pagani, C. Pagano, I. Pailler, F. Palacin, H. Palaversa, L. Parsons, P. Pecoraro, M. Pedrosa, R. Pentikäinen, H. Pichon, B. Piersimoni, A.M. Pineau, F.-X. Plachy, E. Plum, G. Poujoulet, E. Prša, A. Pulone, L. Ragaini, S. Rago, S. Rambaux, N. Ramos-Lerate, M. Ranalli, P. Rauw, G. Read, A. Regibo, S. Reylé, C. Ribeiro, R.A. Rimoldini, L. Ripepi, V. Riva, A. Rixon, G. Roelens, M. Romero-Gómez, M. Rowell, N. Royer, F. Ruiz-Dern, L. Sadowski, G. Sagristà Sellés, T. Sahlmann, J. Salgado, J. Salguero, E. Sarasso, M. Savietto, H. Schultheis, M. Sciacca, E. Segol, M. Segovia, J.C. Segransan, D. Shih, I.-C. Smareglia, R. Smart, R.L. Solano, E. Solitro, F. Sordo, R. Soria Nieto, S. Souchay, J. Spagna, A. Spoto, F. Stampa, U. Steele, I.A. Steidelmüller, H. Stephenson, C.A. Stoev, H. Suess, F.F. Süveges, M. Surdej, J. Szabados, L. Szegedi-Elek, E. Tapiador, D. Taris, F. Tauran, G. Taylor, M.B. Teixeira, R. Terrett, D. Tingley, B. Trager, S.C. Turon, C. Ulla, A. Utrilla, E. Valentini, G. Van Elteren, A. Van Hemelryck, E. Van Leeuwen, M. Varadi, M. Vecchiato, A. Veljanoski, J. Via, T. Vicente, D. Vogt, S. Voss, H. Votruba, V. Voutsinas, S. Walmsley, G. Weiler, M. Weingrill, K. Wevers, T. Wyrzykowski, Ł. Yoldas, A. Žerjal, M. Zucker, S. Zurbach, C. Zwitter, T. Alecu, A. Allen, M. Allende Prieto, C. Amorim, A. Anglada-Escudé, G. Arsenijevic, V. Azaz, S. Balm, P. Beck, M. Bernstein, H.-H. Bigot, L. Bijaoui, A. Blasco, C. Bonfigli, M. Bono, G. Boudreault, S. Bressan, A. Brown, S. Brunet, P.-M. Bunclark, P. Buonanno, R. Butkevich, A.G. Carret, C. Carrion, C. Chemin, L. Chéreau, F. Corcione, L. Darmigny, E. De Boer, K.S. De Teodoro, P. De Zeeuw, P.T. Delle Luche, C. Domingues, C.D. Dubath, P. Fodor, F. Frézouls, B. Fries, A. Fustes, D. Fyfe, D. Gallardo, E. Gallegos, J. Gardiol, D. Gebran, M. Gomboc, A. Gómez, A. Grux, E. Gueguen, A. Heyrovsky, A. Hoar, J. Iannicola, G. Isasi Parache, Y. Janotto, A.-M. Joliet, E. Jonckheere, A. Keil, R. Kim, D.-W. Klagyivik, P. Klar, J. Knude, J. Kochukhov, O. Kolka, I. Kos, J. Kutka, A. Lainey, V. LeBouquin, D. Liu, C. Loreggia, D. Makarov, V.V. Marseille, M.G. Martayan, C. Martinez-Rubi, O. Massart, B. Meynadier, F. Mignot, S. Munari, U. Nguyen, A.-T. Nordlander, T. Ocvirk, P. O'Flaherty, K.S. Olias Sanz, A. Ortiz, P. Osorio, J. Oszkiewicz, D. Ouzounis, A. Palmer, M. Park, P. Pasquato, E. Peltzer, C. Peralta, J. Péturaud, F. Pieniluoma, T. Pigozzi, E. Poels, J. Prat, G. Prod'homme, T. Raison, F. Rebordao, J.M. Risquez, D. Rocca-Volmerange, B. Rosen, S. Ruiz-Fuertes, M.I. Russo, F. Sembay, S. Serraller Vizcaino, I. Short, A. Siebert, A. Silva, H. Sinachopoulos, D. Slezak, E. Soffel, M. Sosnowska, D. Straižys, V. Ter Linden, M. Terrell, D. Theil, S. Tiede, C. Troisi, L. Tsalmantza, P. Tur, D. Vaccari, M. Vachier, F. Valles, P. Van Hamme, W. Veltz, L. Virtanen, J. Wallut, J.-M. Wichmann, R. Wilkinson, M.I. Ziaeepour, H. Zschocke, S.

Abstract

Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the Hipparcos and Tycho-2 catalogues - a realisation of the Tycho-Gaia Astrometric Solution (TGAS) - and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr-1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 Hipparcos stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr-1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data. © ESO, 2016.

Published
2016

22. The SkyMapper DR1.1 search for extremely metal-poor stars.

Author

Da Costa, G S, Bessell, M S, Mackey, A D, Nordlander, T, Asplund, M, Casey, A R, Frebel, A, Lind, K, Marino, A F, Murphy, S J, Norris, J E, Schmidt, B P, and Yong, D

Subjects
DISTRIBUTION (Probability theory), STELLAR atmospheres, STARS, STELLAR populations, ASTRONOMICAL surveys, PHOTOMETRY, ATOMIC hydrogen
Abstract

We present and discuss the results of a search for extremely metal-poor stars based on photometry from data release DR1.1 of the SkyMapper imaging survey of the southern sky. In particular, we outline our photometric selection procedures and describe the low-resolution (R  ≈ 3000) spectroscopic follow-up observations that are used to provide estimates of effective temperature, surface gravity, and metallicity ([Fe/H]) for the candidates. The selection process is very efficient: of the 2618 candidates with low-resolution spectra that have photometric metallicity estimates less than or equal to −2.0, 41 per cent have [Fe/H] ≤ −2.75 and only approximately seven per cent have [Fe/H] > −2.0 dex. The most metal-poor candidate in the sample has [Fe/H] < −4.75 and is notably carbon rich. Except at the lowest metallicities ([Fe/H] < −4), the stars observed spectroscopically are dominated by a 'carbon-normal' population with [C/Fe]1D, LTE ≤ +1 dex. Consideration of the A(C)1D, LTE versus [Fe/H]1D, LTE diagram suggests that the current selection process is strongly biased against stars with A(C)1D, LTE > 7.3 (predominantly CEMP- s) while any bias against stars with A(C)1D, LTE < 7.3 and [C/Fe]1D,LTE > +1 (predominantly CEMP-no) is not readily quantifiable given the uncertainty in the SkyMapper v -band DR1.1 photometry. We find that the metallicity distribution function of the observed sample has a power-law slope of Δ(Log N)/Δ[Fe/H] = 1.5 ± 0.1 dex per dex for −4.0 ≤ [Fe/H] ≤ −2.75, but appears to drop abruptly at [Fe/H] ≈ −4.2, in line with previous studies. [ABSTRACT FROM AUTHOR]

Published
2019
Full Text
View/download PDF

23. The lowest detected stellar Fe abundance: the halo star SMSS J160540.18−144323.1.

Author

Nordlander, T, Bessell, M S, Da Costa, G S, Mackey, A D, Asplund, M, Casey, A R, Chiti, A, Ezzeddine, R, Frebel, A, Lind, K, Marino, A F, Murphy, S J, Norris, J E, Schmidt, B P, and Yong, D

Subjects
*ALKALINE earth metals, *STELLAR populations, *SUPERGIANT stars, *STARS, *KINETIC energy, *SUPERNOVAE, *PLANETARY nebulae
Abstract

We report the discovery of SMSS J160540.18−144323.1, a new ultra metal-poor halo star discovered with the SkyMapper telescope. We measure |$\left[\rm {Fe}/\rm {H}\right]= -6.2 \pm 0.2$| (1D LTE), the lowest ever detected abundance of iron in a star. The star is strongly carbon-enhanced, |$\left[\rm {C}/\rm {Fe}\right] = 3.9 \pm 0.2$|⁠ , while other abundances are compatible with an α-enhanced solar-like pattern with |$\left[\rm {Ca}/\rm {Fe}\right] = 0.4 \pm 0.2$|⁠ , |$\left[\rm {Mg}/\rm {Fe}\right] = 0.6 \pm 0.2$|⁠ , |$\left[\rm {Ti}/\rm {Fe}\right] = 0.8 \pm 0.2$|⁠ , and no significant s- or r-process enrichment, |$\left[\rm {Sr}/\rm {Fe}\right] \lt 0.2$| and |$\left[\rm {Ba}/\rm {Fe}\right] \lt 1.0$| (3σ limits). Population III stars exploding as fallback supernovae may explain both the strong carbon enhancement and the apparent lack of enhancement of odd- Z and neutron-capture element abundances. Grids of supernova models computed for metal-free progenitor stars yield good matches for stars of about |$10\, \rm M_\odot$| imparting a low kinetic energy on the supernova ejecta, while models for stars more massive than roughly |$20\, \rm M_\odot$| are incompatible with the observed abundance pattern. [ABSTRACT FROM AUTHOR]

Published
2019
Full Text
View/download PDF

25. Keck HIRES spectroscopy of SkyMapper commissioning survey candidate extremely metal-poor stars.

Author

Marino, A F, Da Costa, G S, Casey, A R, Asplund, M, Bessell, M S, Frebel, A, Keller, S C, Lind, K, Mackey, A D, Murphy, S J, Nordlander, T, Norris, J E, Schmidt, B P, and Yong, D

Subjects
ALKALINE earth metals, GALACTIC halos, SPECTRUM analysis, STARS, STELLAR populations, SPECTROGRAPHS
Abstract

We present results from the analysis of high-resolution spectra obtained with the Keck HIRES spectrograph for a sample of 17 candidate extremely metal-poor (EMP) stars originally selected from commissioning data obtained with the SkyMapper telescope. Fourteen of the stars have not been observed previously at high dispersion. Three have [Fe/H] ≤ −3.0, while the remainder, with two more metal-rich exceptions, have −3.0 ≤ [Fe/H] ≤ −2.0 dex. Apart from Fe, we also derive abundances for the elements C, N, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, and Zn, and for n -capture elements Sr, Ba, and Eu. None of the current sample of stars is found to be carbon-rich. In general, our chemical abundances follow previous trends found in the literature, although we note that two of the most metal-poor stars show very low [Ba/Fe] (∼−1.7) coupled with low [Sr/Ba] (∼−0.3). Such stars are relatively rare in the Galactic halo. One further star, and possibly two others, meet the criteria for classification as a r -I star. This study, together with that of Jacobson et al. (2015), completes the outcomes of the SkyMapper commissioning data survey for EMP stars. [ABSTRACT FROM AUTHOR]

Published
2019
Full Text
View/download PDF

26. The GALAH Survey: lithium-strong KM dwarfs.

Author

Žerjal, M, Ireland, M J, Nordlander, T, Lin, J, Buder, S, Casagrande, L, Čotar, K, De Silva, G, Horner, J, Martell, S, Traven, G, Zwitter, T, and GALAH Collaboration

Subjects
LITHIUM, COOL stars (Astronomy), PARALLAX, DWARF stars
Abstract

Identifying and characterizing young stars in the Solar neighbourhood is essential to find and describe planets in the early stages of their evolution. This work seeks to identify nearby young stars showing a lithium 6708 Å absorption line in the GALAH survey. A robust, data-driven approach is used to search for corresponding templates in the pool of 434 215 measured dwarf spectra in the survey. It enables a model-free search for best-matching spectral templates for all stars, including M dwarfs with strong molecular absorption bands. 3147 stars have been found to have measurable lithium: 1408 G and 892 K0–K5 dwarfs (EW(Li) > 0.1 Å), 335 K5–K9 (>0.07 Å) and 512 M0–M4 dwarfs (>0.05 Å). Stars with such lithium features are used to investigate the possibility of searching for young stars above the main sequence based merely on their parallaxes and broad-band photometry. The selection of young stars above the main sequence is highly effective for M dwarfs, moderately effective for K dwarfs and ineffective for G dwarfs. Using a combination of the lithium information and the complete 6D kinematics from Gaia and GALAH, 305 new candidate moving group members have been found, 123 of which belong to the Scorpius–Centaurus association, 36 to the Pleiades and 25 to the Hyades clusters. [ABSTRACT FROM AUTHOR]

Published
2019
Full Text
View/download PDF

27. VizieR Online Data Catalog: Gaia FGK benchmark stars: metallicity (Jofre+, 2014)

Author

Jofre, P., Heiter, U., Soubiran, C., Blanco-Cuaresma, S., Pancino, E., Bergemann, M., Cantat-Gaudin, T., Gonzalez Hernandez, J. I., Hill, V., Lardo, C., de Laverny, P., Lind, K., Magrini, L., Masseron, T., Montes, D., Mucciarelli, A., Nordlander, T., Recio Blanco, A., Sobeck, J., Sordo, R., Sousa, S. G., Tabernero, H., Vallenari, A., van Eck, S., and Pomies, Marie-Paule

Subjects
Abundances: [Fe/H], [SDU.ASTR.IM] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Stars: standard, Equivalent widths, [PHYS.ASTR.IM] Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Spectroscopy
Abstract

The metallicity of the Gaia FGK benchmark stars is determined by combining 6 methods. The Tables indicate the iron abundance and equivalent width determined for each star, iron line and method. (5 data files).

Published
2014

29. On the AGB stars of M 4: a robust disagreement between spectroscopic observations and theory.

Author

MacLean, B T, Campbell, S W, Amarsi, A M, Nordlander, T, Cottrell, P L, De Silva, G M, Lattanzio, J, Constantino, T, D'Orazi, V, and Casagrande, L

Subjects
STARS, STAR clusters, SODIUM, MAGNESIUM, ALUMINUM
Abstract

Several recent spectroscopic investigations have presented conflicting results on the existence of Na-rich asymptotic giant branch (AGB) stars in the Galactic globular cluster M 4 (NGC 6121). The studies disagree on whether or not Na-rich red giant branch (RGB) stars evolve to the AGB. For a sample of previously published HERMES/AAT AGB and RGB stellar spectra, we present a re-analysis of O, Na, and Fe abundances, and a new analysis of Mg and Al abundances; we also present CN band strengths for this sample, derived from low-resolution AAOmega spectra. Following a detailed literature comparison, we find that the AGB samples of all studies consistently show lower abundances of Na and Al, and are weaker in CN, than RGB stars in the cluster. This is similar to recent observations of AGB stars in NGC 6752 and M 62. In an attempt to explain this result, we present new theoretical stellar evolutionary models for M 4; however, these predict that all stars, including Na-rich RGB stars, evolve on to the AGB. We test the robustness of our abundance results using a variety of atmospheric models and spectroscopic methods; however, we do not find evidence that systematic modelling uncertainties can explain the apparent lack of Na-rich AGB stars in M 4. We conclude that an unexplained, but robust, discordance between observations and theory remains for the AGB stars in M 4. [ABSTRACT FROM AUTHOR]

Published
2018
Full Text
View/download PDF

30. Effective temperature determinations of late-type stars based on 3D non-LTE Balmer line formation.

Author

Amarsi, A. M., Nordlander, T., Barklem, P. S., Asplund, M., Collet, R., and Lind, K.

Subjects
*COOL stars (Astronomy), *TEMPERATURE measurements, *LOCAL thermodynamic equilibrium, *BALMER line, *HYDRODYNAMICS
Abstract

Hydrogen Balmer lines are commonly used as spectroscopic effective temperature diagnostics of late-type stars. However, reliable inferences require accurate model spectra, and the absolute accuracy of classical methods that are based on one-dimensional (1D) hydrostatic model atmospheres and local thermodynamic equilibrium (LTE) is still unclear. To investigate this, we carry out 3D non-LTE calculations for the Balmer lines, performed, for the first time, over an extensive grid of 3D hydrodynamic STAGGER model atmospheres. For Hα, Hβ, and Hγ we find significant 1D non-LTE versus 3D non-LTE differences (3D effects): the outer wings tend to be stronger in 3D models, particularly for Hγ, while the inner wings can be weaker in 3D models, particularly for Hα. For Hα, we also find significant 3D LTE versus 3D non-LTE differences (non-LTE effects): in warmer stars (Teff ≈ 6500 K) the inner wings tend to be weaker in non-LTE models, while at lower effective temperatures (Teff ≈ 4500 K) the inner wings can be stronger in non-LTE models; the non-LTE effects are more severe at lower metallicities. We test our 3D non-LTE models against observations of well-studied benchmark stars. For the Sun, we infer concordant effective temperatures from Hα, Hβ, and Hγ; however the value is too low by around 50 K which could signal residual modelling shortcomings. For other benchmark stars, our 3D non-LTE models generally reproduce the effective temperatures to within 1σ uncertainties. For Hα, the absolute 3D effects and non-LTE effects can separately reach around 100 K, in terms of inferred effective temperatures. For metal-poor turn-off stars, 1D LTE models of Hα can underestimate effective temperatures by around 150 K. Our 3D non-LTE model spectra are publicly available, and can be used for more reliable spectroscopic effective temperature determinations. [ABSTRACT FROM AUTHOR]

Published
2018
Full Text
View/download PDF

31. 3D NLTE analysis of the most iron-deficient star, SMSS0313-6708.

Author

Nordlander, T., Amarsi, A. M., Lind, K., Asplund, M., Barklem, P. S., Casey, A. R., Collet, R., and Leenaarts, J.

Subjects
*STELLAR evolution, *STELLAR photospheres, *THERMODYNAMIC cycles, *STELLAR spectra, *SUPERNOVAE
Abstract

Context. Models of star formation in the early universe require a detailed understanding of accretion, fragmentation and radiative feedback in metal-free molecular clouds. Different simulations predict different initial mass functions of the first stars, ranging from predominantly low-mass (0.1-10 M⊙ ), to massive (10-100 M⊙ ), or even supermassive (100-1000 M⊙ ). The mass distribution of the first stars should lead to unique chemical imprints on the low-mass second and later generation metal-poor stars still in existence. The chemical composition of SMSS0313-6708, which has the lowest abundances of Ca and Fe of any star known, indicates it was enriched by a single massive supernova. Aims. The photospheres of metal-poor stars are relatively transparent in the UV, which may lead to large three-dimensional (3D) effects as well as departures from local thermodynamical equilibrium (LTE), even for weak spectral lines. If 3D effects and departures from LTE (NLTE) are ignored or treated incorrectly, errors in the inferred abundances may significantly bias the inferred properties of the polluting supernovae. We redetermine the chemical composition of SMSS0313-6708 by means of the most realistic methods available, and compare the results to predicted supernova yields. Methods. A 3D hydrodynamical Stagger model atmosphere and 3D NLTE radiative transfer were applied to obtain accurate abundances for Li, Na, Mg, Al, Ca and Fe. The model atoms employ realistic collisional rates, with no calibrated free parameters. Results. We find significantly higher abundances in 3D NLTE than 1D LTE by 0.8 dex for Fe, and 0.5 dex for Mg, Al and Ca, while Li and Na are unaffected to within 0.03 dex. In particular, our upper limit for [Fe=H] is now a factor ten larger, at [Fe=H] < -6:53 (3σ), than previous estimates based on h3Di NLTE (i.e., using averaged 3D models). This higher estimate is due to a conservative upper limit estimation, updated NLTE data, and 3D-h3Di NLTE differences, all of which lead to a higher abundance determination. Conclusions. We find that supernova yields for models in a wide range of progenitor masses reproduce the revised chemical composition. In addition to massive progenitors of 20-60 M⊙ exploding with low energies (1-2 B, where 1 B = 1051 erg), we also find good fits for progenitors of 10 M⊙, with very low explosion energies (<1 B). We cannot reconcile the new abundances with supernovae or hypernovae with explosion energies above 2.5 B, nor with pair-instability supernovae. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF

32. The Gaia-ESO Survey: radial metallicity gradients and age-metallicity relation of stars in the Milky Way disk.

Author

Bergemann, M., Ruchti, G. R., Serenelli, A., Feltzing, S., Alves-Brito, A., Asplund, M., Bensby, T., Gruiters, P., Heiter, U., Hourihane, A., Korn, A., Lind, K., Marino, A., Jofre, P., Nordlander, T., Ryde, N., Worley, C. C., Gilmore, G., Randich, S., and Ferguson, A. M. N.

Subjects
MILKY Way, GALAXY formation, DISTRIBUTION (Probability theory), PLANETARY nebulae, DISKS (Astrophysics), SPECTRUM analysis
Abstract

We study the relationship between age, metallicity, and α-enhancement of FGK stars in the Galactic disk. The results are based upon the analysis of high-resolution UVES spectra from the Gaia-ESO large stellar survey. We explore the limitations of the observed dataset, i.e. the accuracy of stellar parameters and the selection effects that are caused by the photometric target preselection. We find that the colour and magnitude cuts in the survey suppress old metal-rich stars and young metal-poor stars. This suppression may be as high as 97% in some regions of the age-metallicity relationship. The dataset consists of 144 stars with a wide range of ages from 0.5 Gyr to 13.5 Gyr, Galactocentric distances from 6 kpc to 9.5 kpc, and vertical distances from the plane 0 < ∣Z∣ < 1.5 kpc. On this basis, we find that i) the observed age-metallicity relation is nearly flat in the range of ages between 0 Gyr and 8 Gyr; ii) at ages older than 9 Gyr, we see a decrease in [Fe/H] and a clear absence of metal-rich stars; this cannot be explained by the survey selection functions; iii) there is a significant scatter of [Fe/H] at any age; and iv) [Mg/Fe] increases with age, but the dispersion of [Mg/Fe] at ages >9 Gyr is not as small as advocated by some other studies. In agreement with earlier work, we find that radial abundance gradients change as a function of vertical distance from the plane. The [Mg/Fe] gradient steepens and becomes negative. In addition, we show that the inner disk is not only more α-rich compared to the outer disk, but also older, as traced independently by the ages and Mg abundances of stars. [ABSTRACT FROM AUTHOR]

Published
2014
Full Text
View/download PDF

33. Gaia FGK benchmark stars: Metallicity.

Author

Jofré, P., Heiter, U., Soubiran, C., Blanco-Cuaresma, S., Worley, C. C., Pancino, E., Cantat-Gaudin, T., Magrini, L., Bergemann, M., González Hernández, J. I., Hill, V., Lardo, C., de Laverny, P., Lind, K., Masseron, T., Montes, D., Mucciarelli, A., Nordlander, T., Recio Blanco, A., and Sobeck, J.

Subjects
STAR formation, STELLAR atmospheres, FIELD theory (Physics), ASTRONOMICAL photometry, STELLAR activity
Abstract

Context. To calibrate automatic pipelines that determine atmospheric parameters of stars, one needs a sample of stars, or "benchmark stars", with well-defined parameters to be used as a reference. Aims. We provide detailed documentation of the iron abundance determination of the 34 FGK-type benchmark stars that are selected to be the pillars for calibration of the one billion Gaia stars. They cover a wide range of temperatures, surface gravities, and metallicities. Methods. Up to seven different methods were used to analyze an observed spectral library of high resolutions and high signal-to-noise ratios. The metallicity was determined by assuming a value of effective temperature and surface gravity obtained from fundamental relations, that is, these parameters were known a priori and independently from the spectra. Results. We present a set of metallicity values obtained in a homogeneous way for our sample of benchmark stars. In addition to this value, we provide detailed documentation of the associated uncertainties. Finally, we report a value of the metallicity of the cool giant ψ Phe for the first time. [ABSTRACT FROM AUTHOR]

Published
2014
Full Text
View/download PDF

35. Gaia Data Release 1

Author

Brown, A. G. A., Vallenari, A., Prusti, T., de Bruijne, J. H.J., Mignard, F., Drimmel, R., Babusiaux, C., Bailer-Jones, C. A.L., Bastian, U., Biermann, M., Evans, D. W., Eyer, L., Jansen, F., Jordi, C., Katz, D., Klioner, S. A., Lammers, U., Lindegren, L., Luri, X., O’Mullane, W., Panem, C., Pourbaix, D., Randich, S., Sartoretti, P., Siddiqui, H. I., Soubiran, C., Valette, V., van Leeuwen, F., Walton, N. A., Aerts, C., Arenou, F., Cropper, M., Høg, E., Lattanzi, M. G., Grebel, E. K., Holland, A. D., Huc, C., Passot, X., Perryman, M., Bramante, L., Cacciari, C., Castañeda, J., Chaoul, L., Cheek, N., De Angeli, F., Fabricius, C., Guerra, R., Hernández, J., Jean-Antoine-Piccolo, A., Masana, E., Messineo, R., Mowlavi, N., Nienartowicz, K., Ordóñez-Blanco, D., Panuzzo, P., Portell, J., Richards, P. J., Riello, M., Seabroke, G. M., Tanga, P., Thévenin, F., Torra, J., Els, S. G., Gracia-Abril, G., Comoretto, G., Garcia-Reinaldos, M., Lock, T., Mercier, E., Altmann, M., Andrae, R., Astraatmadja, T. L., Bellas-Velidis, I., Benson, K., Berthier, J., Blomme, R., Busso, G., Carry, B., Cellino, A., Clementini, G., Cowell, S., Creevey, O., Cuypers, J., Davidson, M., De Ridder, J., de Torres, A., Delchambre, L., Dell’Oro, A., Ducourant, C., Frémat, Y., García-Torres, M., Gosset, E., Halbwachs, J.-L., Hambly, N. C., Harrison, D. L., Hauser, M., Hestroffer, D., Hodgkin, S. T., Huckle, H. E., Hutton, A., Jasniewicz, G., Jordan, S., Kontizas, M., Korn, A. J., Lanzafame, A. C., Manteiga, M., Moitinho, A., Muinonen, K., Osinde, J., Pancino, E., Pauwels, T., Petit, J.-M., Recio-Blanco, A., Robin, A. C., Sarro, L. M., Siopis, C., Smith, M., Smith, K. W., Sozzetti, A., Thuillot, W., van Reeven, W., Viala, Y., Abbas, U., Abreu Aramburu, A., Accart, S., Aguado, J. J., Allan, P. M., Allasia, W., Altavilla, G., Álvarez, M. A., Alves, J., Anderson, R. I., Andrei, A. H., Anglada Varela, E., Antiche, E., Antoja, T., Antón, S., Arcay, B., Bach, N., Baker, S. G., Balaguer-Núñez, L., Barache, C., Barata, C., Barbier, A., Barblan, F., Barrado y Navascués, D., Barros, M., Barstow, M. A., Becciani, U., Bellazzini, M., Bello García, A., Belokurov, V., Bendjoya, P., Berihuete, A., Bianchi, L., Bienaymé, O., Billebaud, F., Blagorodnova, N., Blanco-Cuaresma, S., Boch, T., Bombrun, A., Borrachero, R., Bouquillon, S., Bourda, G., Bouy, H., Bragaglia, A., Breddels, M. A., Brouillet, N., Brüsemeister, T., Bucciarelli, B., Burgess, P., Burgon, R., Burlacu, A., Busonero, D., Buzzi, R., Caffau, E., Cambras, J., Campbell, H., Cancelliere, R., Cantat-Gaudin, T., Carlucci, T., Carrasco, J. M., Castellani, M., Charlot, P., Charnas, J., Chiavassa, A., Clotet, M., Cocozza, G., Collins, R. S., Costigan, G., Crifo, F., Cross, N. J.G., Crosta, M., Crowley, C., Dafonte, C., Damerdji, Y., Dapergolas, A., David, P., David, M., De Cat, P., de Felice, F., de Laverny, P., De Luise, F., De March, R., de Martino, D., de Souza, R., Debosscher, J., del Pozo, E., Delbo, M., Delgado, A., Delgado, H. E., Di Matteo, P., Diakite, S., Distefano, E., Dolding, C., Dos Anjos, S., Drazinos, P., Duran, J., Dzigan, Y., Edvardsson, B., Enke, H., Evans, N. W., Eynard Bontemps, G., Fabre, C., Fabrizio, M., Faigler, S., Falcão, A. J., Farràs Casas, M., Federici, L., Fedorets, G., Fernández-Hernández, J., Fernique, P., Fienga, A., Figueras, F., Filippi, F., Findeisen, K., Fonti, A., Fouesneau, M., Fraile, E., Fraser, M., Fuchs, J., Gai, M., Galleti, S., Galluccio, L., Garabato, D., García-Sedano, F., Garofalo, A., Garralda, N., Gavras, P., Gerssen, J., Geyer, R., Gilmore, G., Girona, S., Giuffrida, G., Gomes, M., González-Marcos, A., González-Núñez, J., González-Vidal, J. J., Granvik, M., Guerrier, A., Guillout, P., Guiraud, J., Gúrpide, A., Gutiérrez-Sánchez, R., Guy, L. P., Haigron, R., Hatzidimitriou, D., Haywood, M., Heiter, U., Helmi, A., Hobbs, D., Hofmann, W., Holl, B., Holland, G., Hunt, J. A.S., Hypki, A., Icardi, V., Irwin, M., Jevardat de Fombelle, G., Jofré, P., Jonker, P. G., Jorissen, A., Julbe, F., Karampelas, A., Kochoska, A., Kohley, R., Kolenberg, K., Kontizas, E., Koposov, S. E., Kordopatis, G., Koubsky, P., Krone-Martins, A., Kudryashova, M., Kull, I., Bachchan, R. K., Lacoste-Seris, F., Lanza, A. F., Lavigne, J.-B., Le Poncin-Lafitte, C., Lebreton, Y., Lebzelter, T., Leccia, S., Leclerc, N., Lecoeur-Taibi, I., Lemaitre, V., Lenhardt, H., Leroux, F., Liao, S., Licata, E., Lindstrøm, H. E.P., Lister, T. A., Livanou, E., Lobel, A., Löffler, W., López, M., Lorenz, D., MacDonald, I., Magalhães Fernandes, T., Managau, S., Mann, R. G., Mantelet, G., Marchal, O., Marchant, J. M., Marconi, M., Marinoni, S., Marrese, P. M., Marschalkó, G., Marshall, D. J., Martín-Fleitas, J. M., Martino, M., Mary, N., Matijevič, G., Mazeh, T., McMillan, P. J., Messina, S., Michalik, D., Millar, N. R., Miranda, B. M. H., Molina, D., Molinaro, R., Molinaro, M., Molnár, L., Moniez, M., Montegriffo, P., Mor, R., Mora, A., Morbidelli, R., Morel, T., Morgenthaler, S., Morris, D., Mulone, A. F., Muraveva, T., Musella, I., Narbonne, J., Nelemans, G., Nicastro, L., Noval, L., Ordénovic, C., Ordieres-Meré, J., Osborne, P., Pagani, C., Pagano, I., Pailler, F., Palacin, H., Palaversa, L., Parsons, P., Pecoraro, M., Pedrosa, R., Pentikäinen, H., Pichon, B., Piersimoni, A. M., Pineau, F.-X., Plachy, E., Plum, G., Poujoulet, E., Prša, A., Pulone, L., Ragaini, S., Rago, S., Rambaux, N., Ramos-Lerate, M., Ranalli, P., Rauw, G., Read, A., Regibo, S., Reylé, C., Ribeiro, R. A., Rimoldini, L., Ripepi, V., Riva, A., Rixon, G., Roelens, M., Romero-Gómez, M., Rowell, N., Royer, F., Ruiz-Dern, L., Sadowski, G., Sagristà Sellés, T., Sahlmann, J., Salgado, J., Salguero, E., Sarasso, M., Savietto, H., Schultheis, M., Sciacca, E., Segol, M., Segovia, J. C., Segransan, D., Shih, I.-C., Smareglia, R., Smart, R. L., Solano, E., Solitro, F., Sordo, R., Soria Nieto, S., Souchay, J., Spagna, A., Spoto, F., Stampa, U., Steele, I. A., Steidelmüller, H., Stephenson, C. A., Stoev, H., Suess, F. F., Süveges, M., Surdej, J., Szabados, L., Szegedi-Elek, E., Tapiador, D., Taris, F., Tauran, G., Taylor, M. B., Teixeira, R., Terrett, D., Tingley, B., Trager, S. C., Turon, C., Ulla, A., Utrilla, E., Valentini, G., van Elteren, A., Van Hemelryck, E., van Leeuwen, M., Varadi, M., Vecchiato, A., Veljanoski, J., Via, T., Vicente, D., Vogt, S., Voss, H., Votruba, V., Voutsinas, S., Walmsley, G., Weiler, M., Weingrill, K., Wevers, T., Wyrzykowski, Ł., Yoldas, A., Žerjal, M., Zucker, S., Zurbach, C., Zwitter, T., Alecu, A., Allen, M., Allende Prieto, C., Amorim, A., Anglada-Escudé, G., Arsenijevic, V., Azaz, S., Balm, P., Beck, M., Bernstein, H.-H., Bigot, L., Bijaoui, A., Blasco, C., Bonfigli, M., Bono, G., Boudreault, S., Bressan, A., Brown, S., Brunet, P.-M., Bunclark, P., Buonanno, R., Butkevich, A. G., Carret, C., Carrion, C., Chemin, L., Chéreau, F., Corcione, L., Darmigny, E., de Boer, K. S., de Teodoro, P., de Zeeuw, P. T., Delle Luche, C., Domingues, C. D., Dubath, P., Fodor, F., Frézouls, B., Fries, A., Fustes, D., Fyfe, D., Gallardo, E., Gallegos, J., Gardiol, D., Gebran, M., Gomboc, A., Gómez, A., Grux, E., Gueguen, A., Heyrovsky, A., Hoar, J., Iannicola, G., Isasi Parache, Y., Janotto, A.-M., Joliet, E., Jonckheere, A., Keil, R., Kim, D.-W., Klagyivik, P., Klar, J., Knude, J., Kochukhov, O., Kolka, I., Kos, J., Kutka, A., Lainey, V., LeBouquin, D., Liu, C., Loreggia, D., Makarov, V. V., Marseille, M. G., Martayan, C., Martinez-Rubi, O., Massart, B., Meynadier, F., Mignot, S., Munari, U., Nguyen, A.-T., Nordlander, T., Ocvirk, P., O’Flaherty, K. S., Olias Sanz, A., Ortiz, P., Osorio, J., Oszkiewicz, D., Ouzounis, A., Palmer, M., Park, P., Pasquato, E., Peltzer, C., Peralta, J., Péturaud, F., Pieniluoma, T., Pigozzi, E., Poels, J., Prat, G., Prod’homme, T., Raison, F., Rebordao, J. M., Risquez, D., Rocca-Volmerange, B., Rosen, S., Ruiz-Fuertes, M. I., Russo, F., Sembay, S., Serraller Vizcaino, I., Short, A., Siebert, A., Silva, H., Sinachopoulos, D., Slezak, E., Soffel, M., Sosnowska, D., Straižys, V., ter Linden, M., Terrell, D., Theil, S., Tiede, C., Troisi, L., Tsalmantza, P., Tur, D., Vaccari, M., Vachier, F., Valles, P., Van Hamme, W., Veltz, L., Virtanen, J., Wallut, J.-M., Wichmann, R., Wilkinson, M. I., Ziaeepour, H., and Zschocke, S.

Full Text
View/download PDF

36. ATOMIC DIFFUSION AND MIXING IN OLD STARS. III. ANALYSIS OF NGC 6397 STARS UNDER NEW CONSTRAINTS.

Author

Nordlander, T., Korn, A. J., Richard, O., and Lind, K.

Subjects
*GLOBULAR clusters, *STAR clusters, *COSMIC abundances, *RED giants, *WHITE dwarf stars
Abstract

We have previously reported on chemical abundance trends with evolutionary state in the globular cluster NGC 6397 discovered in analyses of spectra taken with FLAMES at the Very Large Telescope. Here, we reinvestigate the FLAMES-UVES sample of 18 stars, ranging from just above the turnoff point to the red giant branch below the bump. Inspired by new calibrations of the infrared flux method, we adopt a set of hotter temperature scales. Chemical abundances are determined for six elements (Li, Mg, Ca, Ti, Cr, and Fe). Signatures of cluster-internal pollution are identified and corrected for in the analysis of Mg. On the modified temperature scales, evolutionary trends in the abundances of Mg and Fe are found to be significant at the 2σ and 3σ levels, respectively. The detailed evolution of abundances for all six elements agrees with theoretical isochrones, calculated with effects of atomic diffusion and a weak to moderately strong efficiency of turbulent mixing. The age of these models is compatible with the external determination from the white dwarf cooling sequence. We find that the abundance analysis cannot be reconciled with the strong turbulent-mixing efficiency inferred elsewhere for halo field stars. A weak mixing efficiency reproduces observations best, indicating a diffusion-corrected primordial lithium abundance of log ε(Li) = 2.57 ± 0.10. At 1.2σ, this value agrees well with Wilkinson Microwave Anisotropy Probe calibrated big bang nucleosynthesis predictions. [ABSTRACT FROM AUTHOR]

Published
2012
Full Text
View/download PDF

38. The Gaia -ESO Survey: Sodium and aluminium abundances in giants and dwarfs: Implications for stellar and Galactic chemical evolution

Author

Heather R. Jacobson, M. T. Costado, G. G. Sacco, Paolo Donati, Maria Bergemann, Thomas Nordlander, S. G. Sousa, Thomas Bensby, L. Morbidelli, Andrew R. Casey, Rodolfo Smiljanic, Amelia Bayo, Carmela Lardo, Laura Magrini, Donatella Romano, Giovanni Carraro, Sergey E. Koposov, E. Franciosini, Paolo Ventura, James R. Lewis, Sofia Randich, Karin Lind, Luca Sbordone, Angela Bragaglia, P. de Laverny, Antonella Vallenari, Simone Zaggia, Lorenzo Monaco, Ulrike Heiter, A. Hourihane, Alejandra Recio-Blanco, Elena Pancino, Eileen D. Friel, A. C. Lanzafame, Grazina Tautvaisiene, Gerard Gilmore, Paula Jofre, P. Francois, Monica Tosi, Clare Worley, Vanessa Hill, Thierry Morel, V. Adibekyan, Smiljanic R., Romano D., Bragaglia A., Donati P., Magrini L., Friel E., Jacobson H., Randich S., Ventura P., Lind K., Bergemann M., Nordlander T., Morel T., Pancino E., Tautvaisiene G., Adibekyan V., Tosi M., Vallenari A., Gilmore G., Bensby T., Francois P., Koposov S., Lanzafame A.C., Recio-Blanco A., Bayo A., Carraro G., Casey A.R., Costado M.T., Franciosini E., Heiter U., Hill V., Hourihane A., Jofre P., Lardo C., De Laverny P., Lewis J., Monaco L., Morbidelli L., Sacco G.G., Sbordone L., Sousa S.G., Worley C.C., Zaggia S., Gilmore, Gerard [0000-0003-4632-0213], Koposov, Sergey [0000-0003-2644-135X], Casey, Andrew [0000-0003-0174-0564], Worley, Clare [0000-0001-9310-2898], and Apollo - University of Cambridge Repository

Subjects
astro-ph.SR, Stars: abundance, Stellar mass, stars: abundances, astro-ph.GA, Metallicity, Sodium, FOS: Physical sciences, chemistry.chemical_element, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Stars: late-type, 01 natural sciences, evolution [Galaxy], Astronomi, astrofysik och kosmologi, Abundance (ecology), Aluminium, 0103 physical sciences, Astronomy, Astrophysics and Cosmology, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Stellar evolution, QC, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, QB, Physics, Galaxy: evolution, 010308 nuclear & particles physics, abundances [Galaxy], Astronomy and Astrophysics, Galaxy: abundances, Stars: abundances, Stars: evolution, Space and Planetary Science, Astrophysics - Astrophysics of Galaxies, abundances [stars], Galaxy: abundance, Stars, Astrophysics - Solar and Stellar Astrophysics, chemistry, 13. Climate action, evolution [stars], Astrophysics of Galaxies (astro-ph.GA), late-type [stars], Astrophysics::Earth and Planetary Astrophysics, Open cluster
Abstract

Stellar evolution models predict that internal mixing should cause some sodium overabundance at the surface of red giants more massive than ~ 1.5--2.0 Msun. The surface aluminium abundance should not be affected. Nevertheless, observational results disagree about the presence and/or the degree of the Na and Al overabundances. In addition, Galactic chemical evolution models adopting different stellar yields lead to quite different predictions for the behavior of [Na/Fe] and [Al/Fe] versus [Fe/H]. Overall, the observed trends of these abundances with metallicity are not well reproduced. We readdress both issues, using new Na and Al abundances determined within the Gaia-ESO Survey, using two samples: i) more than 600 dwarfs of the solar neighborhood and of open clusters and ii) low- and intermediate-mass clump giants in six open clusters. Abundances of Na in giants with mass below ~2.0 Msun, and of Al in giants below ~3.0 Msun, seem to be unaffected by internal mixing processes. For more massive giants, the Na overabundance increases with stellar mass. This trend agrees well with predictions of stellar evolutionary models. Chemical evolution models that are able to fit well the observed [Na/Fe] vs. [Fe/H] trend in solar neighborhood dwarfs can not simultaneously explain the run of [Al/Fe] with [Fe/H], and viceversa. The comparison with stellar ages is hampered by severe uncertainties. Indeed, reliable age estimates are available for only a half of the stars of the sample. We conclude that Al is underproduced by the models, except for stellar ages younger than about 7 Gyr. In addition, some significant source of late Na production seems to be missing in the models. Either current Na and Al yields are affected by large uncertainties, and/or some important Galactic source(s) of these elements has not been taken into account up to now. [abridged], Comment: 16 pages, 11 figures, A&A accepted, After language editing

Published
2016
Full Text
View/download PDF

39. The Gaia-ESO Survey: A globular cluster escapee in the Galactic halo

Author

Pieter Gruyters, R. D. Jeffries, Carmela Lardo, Sofia Feltzing, Gregory R. Ruchti, Antonella Vallenari, Nils Ryde, Alejandra Recio-Blanco, Caroline Soubiran, Alan Alves-Brito, Maria Bergemann, Anna F. Marino, Martin Asplund, Bengt Edvardsson, Donatella Romano, Aldo Serenelli, Rodolfo Smiljanic, Gerard Gilmore, Thomas Nordlander, Ulrike Heiter, Paul S. Barklem, Annette M. N. Ferguson, S. Blanco-Cuaresma, Paula Jofre, C. Allende Prieto, R. J. Jackson, Angela Bragaglia, Vanessa Hill, Clare Worley, Simone Zaggia, P. de Laverny, Andreas Korn, Sergey E. Koposov, Sofia Randich, Karin Lind, Michele Bellazzini, Francesco Damiani, Elena Pancino, Thomas Bensby, Chiara Battistini, Department of Astronomy and Space Physics [Uppsala], Uppsala University, Dipartimento di Ingegneria industriale e dell'informazione e di economia (DIIIE / UNIVAQ), Università degli Studi dell'Aquila (UNIVAQ), ITA, GBR, FRA, DEU, ESP, SWE, Lind K., Koposov S.E., Battistini C., Marino A.F., Ruchti G., Serenelli A., Worley C.C., Alves-Brito A., Asplund M., Barklem P.S., Bensby T., Bergemann M., Blanco-Cuaresma S., Bragaglia A., Edvardsson B., Feltzing S., Gruyters P., Heiter U., Jofre P., Korn A.J., Nordlander T., Ryde N., Soubiran C., Gilmore G., Randich S., Ferguson A.M.N., Jeffries R.D., Vallenari A., Allende Prieto C., Pancino E., Recio-Blanco A., Romano D., Smiljanic R., Bellazzini M., Damiani F., Hill V., De Laverny P., Jackson R.J., Lardo C., and Zaggia S.

Subjects
Stars: abundance, Population II [stars], Metallicity, Globular clusters: general, FOS: Physical sciences, Techniques: spectroscopic, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Galactic halo, 0103 physical sciences, stellar content [Galaxy], halo [Galaxy], Astrophysics::Solar and Stellar Astrophysics, Omega Centauri, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), general [globular clusters], Astrophysics::Galaxy Astrophysics, QC, QB, Physics, [PHYS]Physics [physics], Galaxy: stellar content, 010308 nuclear & particles physics, Astronomy and Astrophysics, Billion years, Astrophysics - Astrophysics of Galaxies, Galaxy: halo, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], abundances [stars], Red-giant branch, Stars, Astrophysics - Solar and Stellar Astrophysics, Stars: Population II, Space and Planetary Science, Globular cluster, spectroscopic [techniques], Halo, Astrophysics::Earth and Planetary Astrophysics
Abstract

A small fraction of the halo field is made up of stars that share the light element (Z, 4 pages, accepted for publication in Astronomy & Astrophysics

Published
2015
Full Text
View/download PDF

40. Atomic diffusion and mixing in old stars - VIII. Chemical abundance variations in the globular cluster M4 (NGC 6121).

Author

Nordlander T, Gruyters P, Richard O, and Korn AJ

Abstract

Variations in chemical abundances with evolutionary phase have been identified among stars in globular and open clusters with a wide range of metallicities. In the metal-poor clusters, these variations compare well with predictions from stellar structure and evolution models considering the internal diffusive motions of atoms and ions, collectively known as atomic diffusion, when moderated by an additional mixing process with a fine-tuned efficiency. We present here an investigation of these effects in the Galactic globular cluster NGC 6121 (M4) ([Fe/H] = -1.13) through a detailed chemical abundance analysis of 86 stars using high-resolution ESO Very Large Telescope (VLT) Fibre Large Array Multi Element Spectrograph (FLAMES) spectroscopy. The stars range from the main-sequence turnoff point (TOP) to the red giant branch (RGB) just above the bump. We identify C-N-O and Mg-Al-Si abundance anticorrelations, and confirm the presence of a bimodal population differing by 1 dex in nitrogen abundance. The composition of the second-generation stars imply pollution from both massive (20-40 [Formula: see text]) and asymptotic giant branch stars. We find evolutionary variations in chemical abundances between the TOP and RGB, which are robust to uncertainties in stellar parameters and modelling assumptions. The variations are weak, but match predictions well when employing efficient additional mixing. Without correcting for Galactic production of lithium, we derive an initial lithium abundance 2.63 ± 0.10, which is marginally lower than the predicted primordial big-bang nucleosynthesis value., (© 2023 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.)

Published
2023
Full Text
View/download PDF

41. The relationship between photometric and spectroscopic oscillation amplitudes from 3D stellar atmosphere simulations.

Author

Zhou Y, Nordlander T, Casagrande L, Joyce M, Li Y, Amarsi AM, Reggiani H, and Asplund M

Abstract

We establish a quantitative relationship between photometric and spectroscopic detections of solar-like oscillations using ab initio, 3D, hydrodynamical numerical simulations of stellar atmospheres. We present a theoretical derivation as a proof of concept for our method. We perform realistic spectral line formation calculations to quantify the ratio between luminosity and radial velocity amplitude for two case studies: the Sun and the red giant ϵ Tau. Luminosity amplitudes are computed based on the bolometric flux predicted by 3D simulations with granulation background modelled the same way as asteroseismic observations. Radial velocity amplitudes are determined from the wavelength shift of synthesized spectral lines with methods closely resembling those used in Birmingham Solar Oscillations Network (BiSON) and Stellar Oscillations Network Group (SONG) observations. Consequently, the theoretical luminosity to radial velocity amplitude ratios are directly comparable with corresponding observations. For the Sun, we predict theoretical ratios of 21.0 and 23.7 ppm [m s -1 ] -1 from BiSON and SONG, respectively, in good agreement with observations 19.1 and 21.6 ppm [m s -1 ] -1 . For ϵ Tau, we predict K2 and SONG ratios of 48.4 ppm [m s -1 ] -1 , again in good agreement with observations 42.2 ppm [m s -1 ] -1 , and much improved over the result from conventional empirical scaling relations that give 23.2 ppm [m s -1 ] -1 . This study thus opens the path towards a quantitative understanding of solar-like oscillations, via detailed modelling of 3D stellar atmospheres., (© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.)

Published
2021
Full Text
View/download PDF

42. 3D NLTE spectral line formation of lithium in late-type stars.

Author

Wang EX, Nordlander T, Asplund M, Amarsi AM, Lind K, and Zhou Y

Abstract

Accurately known stellar lithium abundances may be used to shed light on a variety of astrophysical phenomena such as big bang nucleosynthesis, radial migration, ages of stars and stellar clusters, and planet engulfment events. We present a grid of synthetic lithium spectra that are computed in non-local thermodynamic equilibrium (NLTE) across the stagger grid of three-dimensional (3D) hydrodynamic stellar atmosphere models. This grid covers three Li lines at 610.4, 670.8, and 812.6 nm for stellar parameters representative of FGK-type dwarfs and giants, spanning T eff = 4000-7000 K, log  g = 1.5-5.0, [Formula: see text]-0.5, and A(Li) = -0.5-4.0. We find that our abundance corrections are up to 0.15 dex more negative than in previous work, due to a previously overlooked NLTE effect of blocking of UV lithium lines by background opacities, which has important implications for a wide range of science cases. We derive a new 3D NLTE solar abundance of A(Li) = 0.96 ± 0.05, which is 0.09 dex lower than the commonly used value. We make our grids of synthetic spectra and abundance corrections publicly available through the breidablik package. This package includes methods for accurately interpolating our grid to arbitrary stellar parameters through methods based on Kriging (Gaussian process regression) for line profiles, and multilayer perceptrons (a class of fully connected feedforward neural networks) for NLTE corrections and 3D NLTE abundances from equivalent widths, achieving interpolation errors of the order of 0.01 dex., (© 2020 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.)

Published
2021
Full Text
View/download PDF

43. Personality factors and drug of choice in female addicts with psychiatric comorbidity.

Author

Gerdner A, Nordlander T, and Pedersen T

Subjects
Adult, Choice Behavior, Female, Humans, Illicit Drugs, Personality Assessment, Psychiatric Status Rating Scales, Psychotic Disorders complications, Substance Abuse Treatment Centers, Substance-Related Disorders complications, Personality, Psychotic Disorders psychology, Substance-Related Disorders psychology
Abstract

Female addicts (N= 108) with a mean age of 37.2 were tested using the Temperament and Character Inventory (TCI) in 1996-97. In a representative sub-sample (N = 49) assessed with the Structured Clinical Interview. DSMIIIr (SCID), 82% manifested an axis-1-syndrome (lifetime), and 53% a personality disorder. Of the 108 addicts, 42 preferred alcohol, 14 heroin, 33 amphetamines, and 19 benzodiazepines. Maturity was low, but there were no differences in maturity between drug preference groups. Results indicated that those less mature were more "novelty-seeking" and "harm-avoidant", while those maturer tended to be more persistent. Less mature persons answered less consistently. They agreed more with different items and their answers were more rare when compared to the general population. Heroin addicts were less sentimental and helpful and more aware of their own resources. Benzodiazepine and amphetamine addicts were more self-transcendent and self-forgetful. Among the relatively more mature, benzodiazepine addicts scored higher than heroin and alcohol addicts on "true" and rare answers. In conclusion, maturity and the drug of choice among female addicts were related to different TCI scales.

Published
2002
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results