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1. Thick disk kinematics from RAVE and the solar motion

Author: Pasetto S. and Grebel E.K.
Subjects: Physics, QC1-999
Abstract: We present a method to derive kinematic parameters for the Galactic thick disk based on stellar radial velocity data alone, without previous knowledge of distances. The prospects and limitations of this method are then explored with the aid of photometric distances. We introduce selection criteria in order to clean the observed radial velocities from the Galactic differential rotation and to take into account the partial sky coverage of RAVE. We deduce the components of the Solar motion relative to the Local Standard of Rest (LSR) in the radial and vertical directions as well as the components of the velocity dispersion tensor. The results extend the analysis already started on the velocity distribution function of the thin and thick disk with RAVE data.
Published: 2012
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2. First results for the solar neighborhood of the Asiago Red Clump Survey

Author: Montalbán J., Pasetto S., Freeman K., Saguner T., Munari U., Valentini M., and Grebel E.K.
Subjects: Physics, QC1-999
Abstract: The Asiago Red Clump Spectroscopic Survey (ARCS) is an ongoing survey that provides atmospheric parameters, distances and space velocities of a well selected sample of Red Clump stars distributed along the celestial equator. We used the ARCS catalog for a preliminary investigation of the Galactic disk in the Solar Neighborhood, in particular we focused on detection and characterization of moving groups.
Published: 2012
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3. Local Group(s)

Author: Grebel, E.K., Leibundgut, Bruno, editor, Saviane, Ivo, editor, Ivanov, Valentin D., editor, and Borissova, Jordanka, editor
Published: 2007
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4. The Gaia-ESO Public Spectroscopic Survey: Implementation, data products, open cluster survey, science, and legacy

Author: Universidad de Alicante. Departamento de Física Aplicada, Randich, Sofia, Gilmore, Gerard, Magrini, L., Sacco, G.G., Jackson, R.J., Jeffries, R., Worley, C.C., Hourihane, A., Gonneau, A., Viscasillas Vázquez, C., Franciosini, E., Sbordone, L., Sousa, S.G., Zaggia, S., Adibekyan, V.Zh., Bonito, R., Caffau, E., Daflon, Simone, Feuillet, D.K., Drazdauskas, A., Gebran, M., Lagarde, N., González Hernández, J.I., Guiglion, G., Herrero, Artemio, Lobel, Alex, Maíz Apellániz, Jesús, Merle, T., Mikolaitis, Š., Montes, David, Morel, Thierry, Evans, N.W., Mahy, Laurent, Soubiran, C., Spina, L., Tabernero, Hugo M., Tautvaišienė, G., Traven, G., Valentini, M., Van der Swaelmen, M., Villanova, S., Wright, N.J., Abbas, U., Mapelli, M., Famaey, B., Aguirre Børsen-Koch, V., Alves, J., Balaguer-Nunez, L., Barklem, P.S., Barrado, D., Berlanas, Sara R., Binks, A.S., Bressan, A., Capuzzo-Dolcetta, R., Marfil, E., Casagrande, L., Franchini, M., Casamiquela, L., Collins, R.S., D'Orazi, V., Dantas, M.L.L., Debattista, V.P., Frémat, Y., Friel, E., Fu, X., Martell, S.L., Geisler, Douglas, Lewis, J., Gerhard, Ortwin, González Solares, E.A., Grebel, E.K., Gutiérrez Albarran, M.L., Hatzidimitriou, D., Held, E.V., Jiménez Esteban, Francisco M., Jönsson, H., Messina, S., Jordi, C., Khachaturyants, T., Alfaro, Emilio J., Kordopatis, G., Kos, J., Miglio, A., Minchev, I., Allende Prieto, C., Moitinho, A., Negueruela, Ignacio, Montalban, J., Monteiro, M.J.P.F.G., Morossi, C., Mowlavi, N., Mucciarelli, A., Murphy, D.N.A., Nardetto, N., Ortolani, S., Paletou, F., Bensby, T., Prusti, T., Palouš, J., Paunzen, E., Pickering, J.C., Quirrenbach, A., Re Fiorentin, P., Read, J.I., Romano, D., Ryde, N., Sanna, N., Santos, W., Rix, H.-W., Blomme, Ronny, Seabroke, G.M., Spagna, A., Steinmetz, M., Stonkuté, E., Sutorius, E., Thévenin, F., Tosi, M., Tsantaki, M., Vink, Jorick S., Vallenari, A., Wright, N., Bragaglia, A., Wyse, R.F.G., Zoccali, M., Zorec, J., Zucker, D.B., Walton, N., Flaccomio, E., François, P., Irwin, M., Bayo, A., Koposov, S., Korn, A., Lanzafame, A.C., Pancino, E., Recio-Blanco, A., Smiljanic, R., Van Eck, S., Zwitter, T., Asplund, M., Bonifacio, P., Bergemann, M., Feltzing, S., Binney, J., Drew, J., Ferguson, A., Micela, G., Biazzo, K., Carraro, G., Casey, A.R., Damiani, F., Delgado-Mena, E., Frasca, A., Heiter, U., Hill, V., Jofre, P., Laverny, P. de, Lind, K., Marconi, G., Martayan, C., Masseron, T., Monaco, L., Di Marcantonio, P., Morbidelli, L., Prisinzano, L., Universidad de Alicante. Departamento de Física Aplicada, Randich, Sofia, Gilmore, Gerard, Magrini, L., Sacco, G.G., Jackson, R.J., Jeffries, R., Worley, C.C., Hourihane, A., Gonneau, A., Viscasillas Vázquez, C., Franciosini, E., Sbordone, L., Sousa, S.G., Zaggia, S., Adibekyan, V.Zh., Bonito, R., Caffau, E., Daflon, Simone, Feuillet, D.K., Drazdauskas, A., Gebran, M., Lagarde, N., González Hernández, J.I., Guiglion, G., Herrero, Artemio, Lobel, Alex, Maíz Apellániz, Jesús, Merle, T., Mikolaitis, Š., Montes, David, Morel, Thierry, Evans, N.W., Mahy, Laurent, Soubiran, C., Spina, L., Tabernero, Hugo M., Tautvaišienė, G., Traven, G., Valentini, M., Van der Swaelmen, M., Villanova, S., Wright, N.J., Abbas, U., Mapelli, M., Famaey, B., Aguirre Børsen-Koch, V., Alves, J., Balaguer-Nunez, L., Barklem, P.S., Barrado, D., Berlanas, Sara R., Binks, A.S., Bressan, A., Capuzzo-Dolcetta, R., Marfil, E., Casagrande, L., Franchini, M., Casamiquela, L., Collins, R.S., D'Orazi, V., Dantas, M.L.L., Debattista, V.P., Frémat, Y., Friel, E., Fu, X., Martell, S.L., Geisler, Douglas, Lewis, J., Gerhard, Ortwin, González Solares, E.A., Grebel, E.K., Gutiérrez Albarran, M.L., Hatzidimitriou, D., Held, E.V., Jiménez Esteban, Francisco M., Jönsson, H., Messina, S., Jordi, C., Khachaturyants, T., Alfaro, Emilio J., Kordopatis, G., Kos, J., Miglio, A., Minchev, I., Allende Prieto, C., Moitinho, A., Negueruela, Ignacio, Montalban, J., Monteiro, M.J.P.F.G., Morossi, C., Mowlavi, N., Mucciarelli, A., Murphy, D.N.A., Nardetto, N., Ortolani, S., Paletou, F., Bensby, T., Prusti, T., Palouš, J., Paunzen, E., Pickering, J.C., Quirrenbach, A., Re Fiorentin, P., Read, J.I., Romano, D., Ryde, N., Sanna, N., Santos, W., Rix, H.-W., Blomme, Ronny, Seabroke, G.M., Spagna, A., Steinmetz, M., Stonkuté, E., Sutorius, E., Thévenin, F., Tosi, M., Tsantaki, M., Vink, Jorick S., Vallenari, A., Wright, N., Bragaglia, A., Wyse, R.F.G., Zoccali, M., Zorec, J., Zucker, D.B., Walton, N., Flaccomio, E., François, P., Irwin, M., Bayo, A., Koposov, S., Korn, A., Lanzafame, A.C., Pancino, E., Recio-Blanco, A., Smiljanic, R., Van Eck, S., Zwitter, T., Asplund, M., Bonifacio, P., Bergemann, M., Feltzing, S., Binney, J., Drew, J., Ferguson, A., Micela, G., Biazzo, K., Carraro, G., Casey, A.R., Damiani, F., Delgado-Mena, E., Frasca, A., Heiter, U., Hill, V., Jofre, P., Laverny, P. de, Lind, K., Marconi, G., Martayan, C., Masseron, T., Monaco, L., Di Marcantonio, P., Morbidelli, L., and Prisinzano, L.
Abstract: Context. In the last 15 years different ground-based spectroscopic surveys have been started (and completed) with the general aim of delivering stellar parameters and elemental abundances for large samples of Galactic stars, complementing Gaia astrometry. Among those surveys, the Gaia-ESO Public Spectroscopic Survey, the only one performed on a 8m class telescope, was designed to target 100 000 stars using FLAMES on the ESO VLT (both Giraffe and UVES spectrographs), covering all the Milky Way populations, with a special focus on open star clusters. Aims. This article provides an overview of the survey implementation (observations, data quality, analysis and its success, data products, and releases), of the open cluster survey, of the science results and potential, and of the survey legacy. A companion article reviews the overall survey motivation, strategy, Giraffe pipeline data reduction, organisation, and workflow. Methods. We made use of the information recorded and archived in the observing blocks; during the observing runs; in a number of relevant documents; in the spectra and master catalogue of spectra; in the parameters delivered by the analysis nodes and the working groups; in the final catalogue; and in the science papers. Based on these sources, we critically analyse and discuss the output and products of the Survey, including science highlights. We also determined the average metallicities of the open clusters observed as science targets and of a sample of clusters whose spectra were retrieved from the ESO archive. Results. The Gaia-ESO Survey has determined homogeneous good-quality radial velocities and stellar parameters for a large fraction of its more than 110 000 unique target stars. Elemental abundances were derived for up to 31 elements for targets observed with UVES. Lithium abundances are delivered for about 1/3 of the sample. The analysis and homogenisation strategies have proven to be successful; several science topics have been addressed by t
Published: 2022

5. The Gaia-ESO Public Spectroscopic Survey: Motivation, implementation, GIRAFFE data processing, analysis, and final data products

Author: Universidad de Alicante. Departamento de Física Aplicada, Gilmore, Gerard, Randich, Sofia, Worley, C.C., Hourihane, A., Gonneau, A., Sacco, G.G., Lewis, J., Magrini, L., François, P., Jeffries, R., Koposov, S., Binks, A.S., Bressan, A., Capuzzo-Dolcetta, R., Casagrande, L., Casamiquela, L., Collins, R.S., D'Orazi, V., Dantas, M.L.L., Debattista, V.P., Delgado-Mena, E., Bragaglia, A., Di Marcantonio, P., Drazdauskas, A., Evans, N.W., Famaey, B., Franchini, M., Frémat, Y., Fu, X., Geisler, Douglas, Gerhard, Ortwin, González Solares, E.A., Alfaro, Emilio J., Grebel, E.K., Gutiérrez Albarrán, M.L., Jiménez Esteban, Francisco M., Jönsson, H., Khachaturyants, T., Kordopatis, G., Kos, J., Lagarde, N., Ludwig, H.-G., Mahy, Laurent, Allende Prieto, C., Mapelli, M., Marfil, E., Martell, S.L., Messina, S., Miglio, A., Minchev, I., Moitinho, A., Montalban, J., Monteiro, M.J.P.F.G., Morossi, C., Blomme, Ronny, Mowlavi, N., Mucciarelli, A., Murphy, D.N.A., Nardetto, N., Ortolani, S., Paletou, F., Palouš, J., Pickering, J.C., Quirrenbach, A., Re Fiorentin, P., Korn, A., Read, J.I., Romano, D., Ryde, N., Sanna, N., Santos, W., Seabroke, G.M., Spina, L., Steinmetz, M., Stonkuté, E., Sutorius, E., Lanzafame, A.C., Thévenin, F., Tosi, M., Tsantaki, M., Wright, N., Wyse, R.F.G., Zoccali, M., Zorec, J., Zucker, D.B., Pancino, E., Recio-Blanco, A., Smiljanic, R., Van Eck, S., Zwitter, T., Bensby, T., Flaccomio, E., Irwin, M., Franciosini, E., Morbidelli, L., Damiani, F., Bonito, R., Friel, E., Vink, Jorick S., Prisinzano, L., Abbas, U., Hatzidimitriou, D., Held, E.V., Jordi, C., Paunzen, E., Spagna, A., Jackson, R.J., Maíz Apellániz, Jesús, Asplund, M., Bonifacio, P., Feltzing, S., Binney, J., Drew, J., Ferguson, A., Micela, G., Negueruela, Ignacio, Prusti, T., Rix, H.-W., Vallenari, A., Bergemann, M., Casey, A.R., Laverny, P. de, Frasca, A., Hill, V., Lind, K., Sbordone, L., Sousa, S.G., Adibekyan, V.Zh., Caffau, E., Daflon, Simone, Feuillet, D.K., Gebran, M., González Hernández, J.I., Guiglion, G., Herrero, Artemio, Lobel, Alex, Merle, T., Mikolaitis, Š., Montes, David, Morel, Thierry, Ruchti, G., Soubiran, C., Tabernero, Hugo M., Tautvaišienė, G., Traven, G., Valentini, M., Van der Swaelmen, M., Villanova, S., Viscasillas Vázquez, C., Bayo, A., Biazzo, K., Carraro, G., Edvardsson, B., Heiter, U., Jofre, P., Marconi, G., Martayan, C., Masseron, T., Monaco, L., Walton, N., Zaggia, S., Aguirre Børsen-Koch, V., Alves, J., Balaguer-Nunez, L., Barklem, P.S., Barrado, D., Bellazzini, M., Berlanas, Sara R., Universidad de Alicante. Departamento de Física Aplicada, Gilmore, Gerard, Randich, Sofia, Worley, C.C., Hourihane, A., Gonneau, A., Sacco, G.G., Lewis, J., Magrini, L., François, P., Jeffries, R., Koposov, S., Binks, A.S., Bressan, A., Capuzzo-Dolcetta, R., Casagrande, L., Casamiquela, L., Collins, R.S., D'Orazi, V., Dantas, M.L.L., Debattista, V.P., Delgado-Mena, E., Bragaglia, A., Di Marcantonio, P., Drazdauskas, A., Evans, N.W., Famaey, B., Franchini, M., Frémat, Y., Fu, X., Geisler, Douglas, Gerhard, Ortwin, González Solares, E.A., Alfaro, Emilio J., Grebel, E.K., Gutiérrez Albarrán, M.L., Jiménez Esteban, Francisco M., Jönsson, H., Khachaturyants, T., Kordopatis, G., Kos, J., Lagarde, N., Ludwig, H.-G., Mahy, Laurent, Allende Prieto, C., Mapelli, M., Marfil, E., Martell, S.L., Messina, S., Miglio, A., Minchev, I., Moitinho, A., Montalban, J., Monteiro, M.J.P.F.G., Morossi, C., Blomme, Ronny, Mowlavi, N., Mucciarelli, A., Murphy, D.N.A., Nardetto, N., Ortolani, S., Paletou, F., Palouš, J., Pickering, J.C., Quirrenbach, A., Re Fiorentin, P., Korn, A., Read, J.I., Romano, D., Ryde, N., Sanna, N., Santos, W., Seabroke, G.M., Spina, L., Steinmetz, M., Stonkuté, E., Sutorius, E., Lanzafame, A.C., Thévenin, F., Tosi, M., Tsantaki, M., Wright, N., Wyse, R.F.G., Zoccali, M., Zorec, J., Zucker, D.B., Pancino, E., Recio-Blanco, A., Smiljanic, R., Van Eck, S., Zwitter, T., Bensby, T., Flaccomio, E., Irwin, M., Franciosini, E., Morbidelli, L., Damiani, F., Bonito, R., Friel, E., Vink, Jorick S., Prisinzano, L., Abbas, U., Hatzidimitriou, D., Held, E.V., Jordi, C., Paunzen, E., Spagna, A., Jackson, R.J., Maíz Apellániz, Jesús, Asplund, M., Bonifacio, P., Feltzing, S., Binney, J., Drew, J., Ferguson, A., Micela, G., Negueruela, Ignacio, Prusti, T., Rix, H.-W., Vallenari, A., Bergemann, M., Casey, A.R., Laverny, P. de, Frasca, A., Hill, V., Lind, K., Sbordone, L., Sousa, S.G., Adibekyan, V.Zh., Caffau, E., Daflon, Simone, Feuillet, D.K., Gebran, M., González Hernández, J.I., Guiglion, G., Herrero, Artemio, Lobel, Alex, Merle, T., Mikolaitis, Š., Montes, David, Morel, Thierry, Ruchti, G., Soubiran, C., Tabernero, Hugo M., Tautvaišienė, G., Traven, G., Valentini, M., Van der Swaelmen, M., Villanova, S., Viscasillas Vázquez, C., Bayo, A., Biazzo, K., Carraro, G., Edvardsson, B., Heiter, U., Jofre, P., Marconi, G., Martayan, C., Masseron, T., Monaco, L., Walton, N., Zaggia, S., Aguirre Børsen-Koch, V., Alves, J., Balaguer-Nunez, L., Barklem, P.S., Barrado, D., Bellazzini, M., and Berlanas, Sara R.
Abstract: Context. The Gaia-ESO Public Spectroscopic Survey is an ambitious project designed to obtain astrophysical parameters and elemental abundances for 100 000 stars, including large representative samples of the stellar populations in the Galaxy, and a well-defined sample of 60 (plus 20 archive) open clusters. We provide internally consistent results calibrated on benchmark stars and star clusters, extending across a very wide range of abundances and ages. This provides a legacy data set of intrinsic value, and equally a large wide-ranging dataset that is of value for the homogenisation of other and future stellar surveys and Gaia's astrophysical parameters. Aims. This article provides an overview of the survey methodology, the scientific aims, and the implementation, including a description of the data processing for the GIRAFFE spectra. A companion paper introduces the survey results. Methods. Gaia-ESO aspires to quantify both random and systematic contributions to measurement uncertainties. Thus, all available spectroscopic analysis techniques are utilised, each spectrum being analysed by up to several different analysis pipelines, with considerable effort being made to homogenise and calibrate the resulting parameters. We describe here the sequence of activities up to delivery of processed data products to the ESO Science Archive Facility for open use. Results. The Gaia-ESO Survey obtained 202 000 spectra of 115 000 stars using 340 allocated VLT nights between December 2011 and January 2018 from GIRAFFE and UVES. Conclusions. The full consistently reduced final data set of spectra was released through the ESO Science Archive Facility in late 2020, with the full astrophysical parameters sets following in 2022. A companion article reviews the survey implementation, scientific highlights, the open cluster survey, and data products.
Published: 2022

6. Chemical Evolution in the Carina Dwarf 1Spheroidal

Author: Koch, A., Grebel, E.K., Harbeck, D., Wilkinson, M.I., Kleyna, J.T., Gilmore, G.F., Wyse, R.F.G., Evans, N.W., Leibundgut, Bruno, editor, Randich, Sofia, editor, and Pasquini, Luca, editor
Published: 2006
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7. The Metallicity-Luminosity Relation for Local Group Dwarf Galaxies

Author: Grebel, E.K., Gallagher, J.S., Harbeck, D., Leibundgut, Bruno, editor, Randich, Sofia, editor, and Pasquini, Luca, editor
Published: 2006
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8. Does Rotation of B Stars Depend on Metallicity? Preliminary Results from GIRAFFE Spectra

Author: Royer, F., North, P., Melo, C., Mermilliod, J.-C., Grebel, E.K., de Medeiros, J.R., Maeder, A., Leibundgut, Bruno, editor, Randich, Sofia, editor, and Pasquini, Luca, editor
Published: 2006
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9. Observed Properties of Dark Matter: dynamical studies of dSph galaxies

Author: Gilmore, G., Wilkinson, M., Kleyna, J., Koch, A., Evans, Wyn, Wyse, R.F.G., and Grebel, E.K.
Published: 2007
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10. Local Group(s)

Author: Grebel, E.K., primary
Published: 2007
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11. Peculiar motions of the gas at the centre of the barred galaxy UGC 4056

Author: German Research Foundation, National Academy of Sciences of Ukraine, Volkswagen Foundation, National Astronomical Observatory of China, National Natural Science Foundation of China, International Space Science Institute, Ministerio de Ciencia, Innovación y Universidades (España), European Commission, Zinchenko, IA, Pilyugin, L.S., Sakhibov, F, Grebel, E.K., Just, A., Berczik, P, Nefedyev, Y.A., Vílchez Medina, José Manuel, Shulga, VM, German Research Foundation, National Academy of Sciences of Ukraine, Volkswagen Foundation, National Astronomical Observatory of China, National Natural Science Foundation of China, International Space Science Institute, Ministerio de Ciencia, Innovación y Universidades (España), European Commission, Zinchenko, IA, Pilyugin, L.S., Sakhibov, F, Grebel, E.K., Just, A., Berczik, P, Nefedyev, Y.A., Vílchez Medina, José Manuel, and Shulga, VM
Abstract: We derive the circular velocity curves of the gaseous and stellar discs of UGC 4056, a giant barred galaxy with an active galactic nucleus (AGN). We analyse UGC 4056 using the 2D spectroscopy obtained within the framework of the Mapping Nearby Galaxies at APO (MaNGA) survey. Using images and the colour index g - r from the Sloan Digital Sky Survey (SDSS), we determined the tilt of the galaxy, which allows us to conclude that the galaxy rotates clockwise with trailing spiral arms. We found that the gas motion at the central part of the UGC 4056 shows peculiar features. The rotation velocity of the gaseous disc shows a bump within around three kiloparsecs while the rotation velocity of the stellar disc falls smoothly to zero with decreasing galactocentric distance. We demonstrate that the peculiar radial velocities in the central part of the galaxy may be caused by the inflow of the gas towards the nucleus of the galaxy. The unusual motion of the gas takes place at the region with the AGN-like radiation and can be explained by the gas response to the bar potential.© ESO 2019
Published: 2019

12. Relations between abundance characteristics and rotation velocity for star-forming MaNGA galaxies

Author: German Research Foundation, Volkswagen Foundation, National Academy of Sciences of Ukraine, Ministerio de Economía y Competitividad (España), Junta de Andalucía, Kazan Federal University, Pilyugin, L.S., Grebel, E.K., Zinchenko, I.A., Nefedyev, Y.A., Vílchez Medina, José Manuel, German Research Foundation, Volkswagen Foundation, National Academy of Sciences of Ukraine, Ministerio de Economía y Competitividad (España), Junta de Andalucía, Kazan Federal University, Pilyugin, L.S., Grebel, E.K., Zinchenko, I.A., Nefedyev, Y.A., and Vílchez Medina, José Manuel
Abstract: We derive rotation curves, surface brightness profiles, and oxygen abundance distributions for 147 late-type galaxies using the publicly available spectroscopy obtained by the MaNGA survey. Changes of the central oxygen abundance (O/H)0, the abundance at the optical radius (O/H)R25, and the abundance gradient with rotation velocity Vrot were examined for galaxies with rotation velocities from 90 km s to 350 km s. We find that each relation shows a break at Vrot ∼ 200 km s. The central (O/H)0 abundance increases with rising Vrot and the slope of the (O/H)0-Vrot relation is steeper for galaxies with Vrot Vrot. The mean scatter of the central abundances around this relation is 0.053 dex. The relation between the abundance at the optical radius of a galaxy and its rotation velocity is similar; the mean scatter in abundances around this relation is 0.081 dex. The radial abundance gradient expressed in dex/kpc flattens with the increase of the rotation velocity. The slope of the relation is very low for galaxies with Vrot Vrot. The abundance gradient expressed in dex/R25 is roughly constant for galaxies with Vrot Vrot, flattens towards Vrot, and then again is roughly constant for galaxies with Vrot Vrot. The change of the gradient expressed in terms of dex/hd (where hd is the disc scale length), in terms of dex/Re, d (where Re, d is the disc effective radius), and in terms of dex/Re, g (where Re, g is the galaxy effective radius) with rotation velocity is similar to that for gradient in dex/R25. The relations between abundance characteristics and other basic parameters (stellar mass, luminosity, and radius) are also considered.
Published: 2019

13. The Gaia-ESO Survey: Evidence of atomic diffusion in M67?

Author: German Research Foundation, Ministerio de Economía y Competitividad (España), Research Council of Lithuania, Swedish National Space Board, Knut and Alice Wallenberg Foundation, Fundação para a Ciência e a Tecnologia (Portugal), Australian Research Council, European Commission, Swiss National Science Foundation, Ministerio de Economía, Fomento y Turismo (Chile), Science and Technology Facilities Council (UK), Leverhulme Trust, Istituto Nazionale di Astrofisica, Bertelli Motta, C., Pasquali, A., Richer, J., Michaud, G., Salaris, M., Bragaglia, A., Magrini, L., Randich, S., Grebel, E.K., Adibekyan, V., Blanco-Cuaresma, S., Drazdauskas, A., Fu, X., Martell, S., Tautvaišiene, G., Gilmore, Gerry, Alfaro, Emilio J., Bensby, T., Flaccomio, E., Koposov, S.E., Korn, A.J., Lanzafame, A.C., Smiljanic, R., Bayo, A., Carraro, G., Casey, A. R., Costado, M. T., Damiani, F., Franciosini, E., Heiter, Ulrike, Hourihane, A., Jofré, P., Lardo, C., Lewis, J., Monaco, L., Morbidelli, L., Sacco, G. G., Sousa, S.G., Worley, C.C., Zaggia, S., German Research Foundation, Ministerio de Economía y Competitividad (España), Research Council of Lithuania, Swedish National Space Board, Knut and Alice Wallenberg Foundation, Fundação para a Ciência e a Tecnologia (Portugal), Australian Research Council, European Commission, Swiss National Science Foundation, Ministerio de Economía, Fomento y Turismo (Chile), Science and Technology Facilities Council (UK), Leverhulme Trust, Istituto Nazionale di Astrofisica, Bertelli Motta, C., Pasquali, A., Richer, J., Michaud, G., Salaris, M., Bragaglia, A., Magrini, L., Randich, S., Grebel, E.K., Adibekyan, V., Blanco-Cuaresma, S., Drazdauskas, A., Fu, X., Martell, S., Tautvaišiene, G., Gilmore, Gerry, Alfaro, Emilio J., Bensby, T., Flaccomio, E., Koposov, S.E., Korn, A.J., Lanzafame, A.C., Smiljanic, R., Bayo, A., Carraro, G., Casey, A. R., Costado, M. T., Damiani, F., Franciosini, E., Heiter, Ulrike, Hourihane, A., Jofré, P., Lardo, C., Lewis, J., Monaco, L., Morbidelli, L., Sacco, G. G., Sousa, S.G., Worley, C.C., and Zaggia, S.
Abstract: Investigating the chemical homogeneity of stars born from the same molecular cloud at virtually the same time is very important for our understanding of the chemical enrichment of the interstellar medium and with it the chemical evolution of the Galaxy. One major cause of inhomogeneities in the abundances of open clusters is stellar evolution of the cluster members. In this work, we investigate variations in the surface chemical composition of member stars of the old open clusterM67 as a possible consequence of atomic diffusion effects taking place during the main-sequence phase. The abundances used are obtained from high-resolution UVES/FLAMES spectra within the framework of the Gaia-ESO Survey. We find that the surface abundances of stars on the main sequence decrease with increasing mass reaching a minimum at the turn-off. After deepening of the convective envelope in subgiant branch stars, the initial surface abundances are restored.We found themeasured abundances to be consistent with the predictions of stellar evolutionary models for a cluster with the age and metallicity of M67. Our findings indicate that atomic diffusion poses a non-negligible constraint on the achievable precision of chemical tagging methods.© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.
Published: 2018

14. Spiral arms in CALIFA galaxies traced by non-circular velocities, abundances and extinctions

Author: German Research Foundation, Volkswagen Foundation, Sakhibov, F., Zinchenko, I. A., Pilyugin, L.S., Grebel, E.K., Just, A., Vílchez Medina, José Manuel, German Research Foundation, Volkswagen Foundation, Sakhibov, F., Zinchenko, I. A., Pilyugin, L.S., Grebel, E.K., Just, A., and Vílchez Medina, José Manuel
Abstract: We derive maps of the observed velocity of ionized gas, the oxygen abundance and the extinction (Balmer decrement) across the area of the four spiral galaxies NGC 36, NGC 180, NGC 6063 and NGC 7653 from integral field spectroscopy obtained by the Calar Alto Legacy Integral Field Area (CALIFA) survey. We searched for spiral arms through Fourier analysis of the spatial distribution of three tracers (non-circular motion, enhancement of the oxygen abundance and of the extinction) in the discs of our target galaxies. The spiral arms (twoarmed logarithmic spirals in the deprojected map) are shown in each target galaxy for each tracer considered. The pitch angles of the spiral arms in a given galaxy obtained with the three different tracers are close to each other. The enhancement of the oxygen abundance in the spiral arms as compared to the abundance in the interarm regions at a given galactocentric distance is small, within a few per cent. We identified a metallicity gradient in our target galaxies. Both barred galaxies in our sample show flatter gradients than the two galaxies without bars. Galactic inclination, position angle of the major axis and the rotation curve were also obtained for each target galaxy using the Fourier analysis of the two-dimensional velocity map.© 2017 The Author(s).
Published: 2018

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. 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

17. Evidence for multiple populations in intermediate age cluster Lindsay 1 in the SMC

Author: Hollyhead, K., Kacharov, N., Lardo, C., Bastian, N., Hilker, M., Rejkuba, M., Koch, Andreas, Grebel, E.K., Georgiev, I., Hollyhead, K., Kacharov, N., Lardo, C., Bastian, N., Hilker, M., Rejkuba, M., Koch, Andreas, Grebel, E.K., and Georgiev, I.
Abstract: Lindsay 1 is an intermediate age (≈8 Gyr) massive cluster in the Small Magellanic Cloud (SMC). Using VLT FORS2 spectra of 16 probable cluster members on the lower RGB of the cluster, we measure CN and CH band strengths (at ≃ 3883 and 4300 Å respectively), along with carbon and nitrogen abundances and find that a sub-population of stars has significant nitrogen enrichment. A lack of spread in carbon abundances excludes evolutionary mixing as the source of this enrichment, so we conclude that this is evidence of multiple populations. Therefore, L1 is the youngest cluster to show such variations, implying that the process triggering the onset of multiple populations must operate until at least redshift ∼1.
Published: 2017

18. Breaks in surface brightness profiles and radial abundance gradients in the discs of spiral galaxies

Author: Pilyugin, L.S., Grebel, E.K., Zinchenko, I.A., Nefedyev, Y.A., Vílchez Medina, José Manuel, Pilyugin, L.S., Grebel, E.K., Zinchenko, I.A., Nefedyev, Y.A., and Vílchez Medina, José Manuel
Abstract: We examine the relation between breaks in the surface brightness profiles and radial abundance gradients within the optical radius in the discs of 134 spiral galaxies from the CALIFA survey. The distribution of the radial abundance (in logarithmic scale) in each galaxy was fitted by simple and broken linear relations. The surface brightness profile was fitted assuming pure and broken exponents for the disc. We find that the maximum absolute difference between the abundances in a disc given by broken and pure linear relations is less than 0.05 dex in the majority of our galaxies and exceeds the scatter in abundances for 26 out of 134 galaxies considered. The scatter in abundances around the broken linear relation is close (within a few percent) to that around the pure linear relation. The breaks in the surface brightness profiles are more prominent. The scatter around the broken exponent in a number of galaxies is lower by a factor of two or more than that around the pure exponent. The shapes of the abundance gradients and surface brightness profiles within the optical radius in a galaxy may be different. A pure exponential surface brightness profile may be accompanied by a broken abundance gradient and vise versa. There is no correlation between the break radii of the abundance gradients and surface brightness profiles. Thus, a break in the surface brightness profile does not need to be accompanied by a break in the abundance gradient.© ESO, 2017.
Published: 2017

19. 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., González-Marcos, Ana., and A. Bello García
Subjects: instruments [Space vehicles], Parallaxes, Astrometry, Proper motions, structure [Galaxy], Telescopes
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. © ESO, 2016.
Published: 2016

20. 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., and González-Marcos, Ana.
Subjects: Parallaxes, Astrometry, Proper motions, Catalogs, Surveys
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

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. Hubble Tarantula Treasury Project. III. Photometric Catalog and Resulting Constraints on the Progression of Star Formation in the 30 Doradus Region

Author: Sabbi, E., Lennon, D.J., Anderson, J., Cignoni, M., Marel, R.P. van der, Zaritsky, D., Marchi, G. de, Panagia, N., Gouliermis, D.A., Grebel, E.K., Gallagher, J.S., Smith, L.J., Sana, H., Aloisi, A., Tosi, M., Evans, C.J., Arab, H., Boyer, M., Mink, S.E. de, Gordon, K., Koekemoer, A.M., Larsen, S.S., Ryon, J.E., Zeidler, P., Sabbi, E., Lennon, D.J., Anderson, J., Cignoni, M., Marel, R.P. van der, Zaritsky, D., Marchi, G. de, Panagia, N., Gouliermis, D.A., Grebel, E.K., Gallagher, J.S., Smith, L.J., Sana, H., Aloisi, A., Tosi, M., Evans, C.J., Arab, H., Boyer, M., Mink, S.E. de, Gordon, K., Koekemoer, A.M., Larsen, S.S., Ryon, J.E., and Zeidler, P.
Abstract: Contains fulltext : 155817.pdf (publisher's version ) (Open Access)
Published: 2016

23. Hubble Tarantula Treasury Project - IV. The extinction law

Author: Marchi, G. de, Panagia, N., Sabbi, E., Lennon, D., Anderson, J., Marel, R. van der, Cignoni, M., Grebel, E.K., Larsen, S.S., Zaritsky, D., Zeidler, P., Gouliermis, D., Aloisi, A., Marchi, G. de, Panagia, N., Sabbi, E., Lennon, D., Anderson, J., Marel, R. van der, Cignoni, M., Grebel, E.K., Larsen, S.S., Zaritsky, D., Zeidler, P., Gouliermis, D., and Aloisi, A.
Abstract: Contains fulltext : 155816.pdf (preprint version ) (Open Access)
Published: 2016

24. Erratum: Hubble Tarantula Treasury Project - IV. The extinction law (vol 455, pg 4373, 2016)

Author: Marchi, G. de, Panagia, N., Sabbi, E., Lennon, D., Anderson, J., Marel, R. van der, Cignoni, M., Grebel, E.K., Larsen, S.S., Zaritsky, D., Zeidler, P., Gouliermis, D., Aloisi, A., Marchi, G. de, Panagia, N., Sabbi, E., Lennon, D., Anderson, J., Marel, R. van der, Cignoni, M., Grebel, E.K., Larsen, S.S., Zaritsky, D., Zeidler, P., Gouliermis, D., and Aloisi, A.
Abstract: Contains fulltext : 157915.pdf (publisher's version ) (Open Access)
Published: 2016

25. Hubble Tarantula Treasury Project V. The Star Cluster Hodge 301: The Old Face of 30 Doradus

Author: Cignoni, M., Sabbi, E., Marel, R.P. van der, Lennon, D.J., Tosi, M., Grebel, E.K., Gallagher, J.S., III, Aloisi, A., Marchi, G. de, Gouliermis, D.A., Larsen, S., Panagia, N., Smith, L.J., Cignoni, M., Sabbi, E., Marel, R.P. van der, Lennon, D.J., Tosi, M., Grebel, E.K., Gallagher, J.S., III, Aloisi, A., Marchi, G. de, Gouliermis, D.A., Larsen, S., Panagia, N., and Smith, L.J.
Abstract: Contains fulltext : 166004.pdf (publisher's version ) (Open Access)
Published: 2016

26. GREAT-ITN and Gaia: Preparing for Science

Author: WALTON, N.A., BAILER-JONES, C.A.L., BROWN, A.G.A., CLEMENTINI, G., EYER, L., FELTZING, S., FIGUERAS, F., GREBEL, E.K., MICHALOWSKI, T., RIDDER, J. De, SANTOS, N., SMITH, M.C., SOUBIRAN, C., BALAGUER-NÚÑEZ, L., Institute of Astronomy [Cambridge], University of Cambridge [UK] (CAM), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Geneva Observatory, University of Geneva [Switzerland], Lund Observatory, Lund University [Lund], Universitat de Barcelona (UB), Adam Mickiewicz University in Poznań (UAM), Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Centro de Astrofísica da Universidade do Porto (CAUP), Universidade do Porto, Departamento de Física e Astronomia [Porto] (DFA/FCUP), Faculdade de Ciências da Universidade do Porto (FCUP), Universidade do Porto-Universidade do Porto, National Optical Astronomy Observatory, M2A 2015, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), and Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Engineering management, Initial training, 010308 nuclear & particles physics, Space and Planetary Science, 0103 physical sciences, General Engineering, Astronomy and Astrophysics, 010303 astronomy & astrophysics, 01 natural sciences, Engineering physics, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM]
Abstract: International audience; his paper gives a brief overview of the Gaia Research for European Astronomy Training (GREAT) network, including a description of the GREAT-ESF Research Network Programme and the GREAT Initial Training Network (GREAT-ITN). Scientific highlights from the GREAT-ITN are noted.
Published: 2014

27. Galaxy evolution through resolved stellar populations in the nearby Centaurus A group

Author: Crnojevic, D., Grebel, E.K., Ferguson, Annette M. N., Koch, Andreas, Rejkuba, M., Da Costa, G., Jerjen, H., Irwin, Michael J., Bernard, E. J., Arimoto, Nobuo, Jablonka, P., Kobayashi, Chiaki, Crnojevic, D., Grebel, E.K., Ferguson, Annette M. N., Koch, Andreas, Rejkuba, M., Da Costa, G., Jerjen, H., Irwin, Michael J., Bernard, E. J., Arimoto, Nobuo, Jablonka, P., and Kobayashi, Chiaki
Abstract: The CenA group is a nearby dense complex (∼ 4 Mpc) dominated by an active elliptical galaxy, hosting more than 60 dwarf companions with a variety of morphological types and stellar contents. We study the resolved stellar populations of a sample of dwarfs using optical and near-infrared data from ACS/HST and ISAAC/VLT. We characterize their recent star formation histories and metallicity content, and compare them to what is known for Local Group dwarfs, underlining similarities and differences. Our results probe the fu ndamental interplay between nature and nurture in the evolution of dwarfs in such a dense environment. We further present the results of the first deep survey of resolved stellar populations in the remote outer halo of our nearest giant elliptical, CenA (VIMOS/VLT optical data). Tracing its halo structure (radial profile, extent and metallicity) out to a remarkable ∼ 85 kpc and comparing the halo stellar populations to those of CenA’s dwarf companions enables us to constrain the mechanisms that contributed to the build-up of CenA in the context of cosmological galaxy formation models.
Published: 2015

28. The velocity dispersion and mass function of the outer halo globular cluster Palomar 4

Author: Frank, M.J., Hilker, M., Baumgardt, H., Côté, P., Grebel, E.K., Haghi, H., Küpper, A.H.W., and Djorgovski, S.G.
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics::Galaxy Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: We obtained precise line-of-sight radial velocities of 23 member stars of the remote halo globular cluster Palomar 4 (Pal 4) using the High Resolution Echelle Spectrograph (HIRES) at the Keck I telescope. We also measured the mass function of the cluster down to a limiting magnitude of V~28 mag using archival HST/WFPC2 imaging. We derived the cluster's surface brightness profile based on the WFPC2 data and on broad-band imaging with the Low-Resolution Imaging Spectrometer (LRIS) at the Keck II telescope. We find a mean cluster velocity of 72.55+/-0.22 km/s and a velocity dispersion of 0.87+/-0.18 km/s. The global mass function of the cluster, in the mass range 0.55, 17 pages, accepted for publication in MNRAS; Fig. 8 surface brightness/density data at github.com/matthiasjfrank/pal4_surface_brightness
Published: 2012

29. Dwarf Galaxies Beyond Our Doorstep: the Centaurus Group

Author: Crnojevic, Denija, Grebel, E.K., Cole, A.A., Koch, A., Rejkuba, M., Da Costa, G., Jerjen, H., and Zahn, Jean-Paul
Subjects: astro-ph.CO, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: The study of dwarf galaxies in groups is a powerful tool for investigating galaxy evolution, chemical enrichment and environmental effects on these objects. Here we present results obtained for dwarf galaxies in the Centaurus A complex, a dense nearby (~4 Mpc) group that contains two giant galaxies and about 30 dwarf companions of different morphologies and stellar contents. We use archival optical (HST/ACS) and near-infrared (VLT/ISAAC) data to derive physical properties and evolutionary histories from the resolved stellar populations of these dwarf galaxies. In particular, for early-type dwarfs we are able to construct metallicity distribution functions, find population gradients and quantify the intermediate-age star formation episodes. For late-type dwarfs, we compute recent (~1 Gyr) star formation histories and study their stellar distribution. We then compare these results with properties of the dwarfs in our Milky Way and in other groups. Our work will ultimately lead to a better understanding of the evolution of dwarf galaxies.
Published: 2011

30. A Roadmap for Delivering the Promise of Gaia

Author: Prusti, T., Aerts, C.C., Grebel, E.K., Jordi, C., Klioner, S.A., Lindegren, L., Mignard, F., Randich, S., Walton, N.A., Andersen, J., and Andersen, J.
Subjects: 010504 meteorology & atmospheric sciences, Astronomy, Library science, Astronomy and Astrophysics, Astrometry, 01 natural sciences, Data science, Geography, Space and Planetary Science, 0103 physical sciences, 010303 astronomy & astrophysics, S254, 0105 earth and related environmental sciences
Abstract: Gaia development is in full speed aiming to the launch in December 2011. While the entities formally responsible to make Gaia happen are very focused to be ready in time, it is necessary to explore the readiness of the wider scientific community to exploit Gaia data in the future. The GST sees a role for itself in building and enabling the community to use the Gaia catalogues when they become available. This paper gives the background for the current activities the GST is taking to promote the community to start preparations for the exploitation of Gaia data.
Published: 2009
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31. Chemical Evolution in the Carina Dwarf 1Spheroidal

Author: Koch, A., primary, Grebel, E.K., additional, Harbeck, D., additional, Wilkinson, M.I., additional, Kleyna, J.T., additional, Gilmore, G.F., additional, Wyse, R.F.G., additional, and Evans, N.W., additional
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32. Does Rotation of B Stars Depend on Metallicity? Preliminary Results from GIRAFFE Spectra

Author: Royer, F., primary, North, P., additional, Melo, C., additional, Mermilliod, J.-C., additional, Grebel, E.K., additional, de Medeiros, J.R., additional, and Maeder, A., additional
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33. The Metallicity-Luminosity Relation for Local Group Dwarf Galaxies

Author: Grebel, E.K., primary, Gallagher, J.S., additional, and Harbeck, D., additional
Full Text: View/download PDF

34. Tracing the Sgr Tails with LPV Carbon Stars

Author: Huxor, A.P., primary and Grebel, E.K., additional
Published: 2014
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35. Blue Horizontal Branch Stars in Pan-STARRS

Author: Vickers, J.J., primary, Huxor, A.P., additional, and Grebel, E.K., additional
Published: 2014
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36. GREAT-ITN and Gaia: Preparing for Science

Author: Walton, N.A., primary, Bailer-Jones, C.A.L., additional, Brown, A.G.A., additional, Clementini, G., additional, Eyer, L., additional, Feltzing, S., additional, Figueras, F., additional, Grebel, E.K., additional, Michalowski, T., additional, Ridder, J. De, additional, Santos, N., additional, Smith, M.C., additional, and Soubiran, C., additional
Published: 2014
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37. Hubble Tarantula Treasury Project: Unraveling Tarantula's Web. I. Observational Overview and First Results

Author: Sabbi, S., Anderson, I., Lennon, D.J., Marel, R.P. van der, Aloisi, A., Boyer, M.L., Cignoni, M., Marchi, G. de, Mink, S.E. de, Evans, C.J., Gallagher, J.S., Gordon, K., Gouliermis, D.A., Grebel, E.K., Koekemoer, A.M., Larsen, S.S., Panagia, N., Ryon, J.E., Smith, L.J., Tosi, M., Zaritsky, D., Sabbi, S., Anderson, I., Lennon, D.J., Marel, R.P. van der, Aloisi, A., Boyer, M.L., Cignoni, M., Marchi, G. de, Mink, S.E. de, Evans, C.J., Gallagher, J.S., Gordon, K., Gouliermis, D.A., Grebel, E.K., Koekemoer, A.M., Larsen, S.S., Panagia, N., Ryon, J.E., Smith, L.J., Tosi, M., and Zaritsky, D.
Abstract: Contains fulltext : 117036.pdf (preprint version ) (Open Access)
Published: 2013

38. Population gradients and photometric metallicities in early- and transition-type dwarf galaxies:clues from the Sculptor group

Author: Lianou, S., Grebel, E.K., Da Costa, G. S., Rejkuba, M., Jerjen, H., Koch, Andreas, Lianou, S., Grebel, E.K., Da Costa, G. S., Rejkuba, M., Jerjen, H., and Koch, Andreas
Abstract: Aims. We focus on the resolved stellar populations of one early-type and four transition-type dwarf galaxies in the Sculptor group, with the aim to examine the potential presence of population gradients and place constraints on their mean metallicities. Methods. We use deep Hubble Space Telescope images to construct color–magnitude diagrams, from which we select stellar populations that trace different evolutionary phases in order to constrain their range of ages and metallicities, as well as to examine their spatial distribution. In addition, we use the resolved stars in the red giant branch in order to derive photometric metallicities. Results. All studied dwarfs contain intermediate-age stars with ages of ~1 Gyr and older as traced by the luminous asymptotic giant branch and red clump stars, while the transition-type dwarfs contain also stars younger than ~1 Gyr as traced by a young main sequence and vertical red clump stars. Moreover, the spatial distribution of the stars that trace different evolutionary phases shows a population gradient in all transition-type dwarfs. The derived error-weighted mean metallicities, assuming purely old stellar populations, range from −1.5 dex for ESO294-G010 to −1.9 dex for Scl-dE1, and should be considered as lower limits to their true metallicities. Assuming intermediate-age stellar populations to dominate the dwarfs, we derive upper limits for the metallicities that are 0.3 to 0.2 dex higher than the metallicities derived assuming purely old populations. We discuss how photometric metallicity gradients are affected by the age-metallicity degeneracy, which prevents strong conclusions regarding their actual presence. Finally, the transition-type dwarfs lie beyond the virial radius of their closest bright galaxy, as also observed for the Local Group transition-type dwarfs. Scl-dE1 is the only dwarf spheroidal in our sample and is an outlier in a potential morphology-distance relation, similar as the two isolated dwarf spheroidal
Published: 2013

39. The metallicity-redshift relations for emission-line SDSS galaxies:examination of the dependence on the star formation rate

Author: Piyugin, L.S., Lara-Lopez, M.A., Grebel, E.K., Kehrig, C., Zinchenko, I.A., Lopez-Sanchez, A.R., Vilchez, J.M., Mattsson, Lars Mattias, Piyugin, L.S., Lara-Lopez, M.A., Grebel, E.K., Kehrig, C., Zinchenko, I.A., Lopez-Sanchez, A.R., Vilchez, J.M., and Mattsson, Lars Mattias
Published: 2013

40. 'Counterpart' method for abundance determinations in H II regions

Author: Pilyugin, L.S., Grebel, E.K., Mattsson, Lars Mattias, Pilyugin, L.S., Grebel, E.K., and Mattsson, Lars Mattias
Published: 2012

41. Activated growth signaling pathway expression in Ewing sarcoma and clinical outcome

Author: Ministerio de Ciencia e Innovación (España), Mora, Jaume, Rodríguez, Eva, Torres, Carmen de, Cardesa, Teresa, Ríos, José, Grebel, E.K., Hernández, Mª Teresa, Cardesa, Antonio, Álava, Enrique de, Ministerio de Ciencia e Innovación (España), Mora, Jaume, Rodríguez, Eva, Torres, Carmen de, Cardesa, Teresa, Ríos, José, Grebel, E.K., Hernández, Mª Teresa, Cardesa, Antonio, and Álava, Enrique de
Abstract: [Background]: In Ewing sarcoma (EWS) most of the research on signaling pathways has been performed on cell lines or animal models. The objective of the current study was to determine the relation between clinical outcome and the expression of proteins involved in active growth signaling pathways. [Methods]: A paraffin-embedded microarray of 45 human primary EWS tissue specimens was stained with the antibodies against c-KIT, AKT, p-AKT, p-mTOR, IGF-1R, IGFBP-3, MAPK, p27 KIP1, and p70S6 kinase. Immunohistochemical staining was correlated with patient overall survival (OS). [Results]: In the univariate analysis 3 variables showed statistical significance to predict survival: presence of metastasis, p-mTOR, and p27 KIP1. A positive stain for p-mTOR (hazard ratio of 4.74 [95% CI (57, 121)]) was significantly (log-rank test with a P=0.029) associated with better OS. Also, a positive stain for p27 KIP1 (hazard ratio of 6.87 [95% CI (77, 136)] was significantly (log-rank test with a P=0.009) associated with better OS. Multivariate analysis showed metastasis (HR: 4.3; 95% CI: 0.99, 19; P=0.05), p-mTOR (HR: 4.8 with 95% CI: 0.6, 38; P=0.13) and p27 (HR: 5.3; 95% CI: 1.37, 20; P=0.01) as independent prognostic factors of outcome. [Conclusions]: In our series, p-mTOR and p27 KIP1 protein overexpression were independently associated with better survival. © 2011 Wiley Periodicals, Inc.
Published: 2012

42. How unique is the Local Group?:A comparison to the nearby Centaurus A group

Author: Crnojevic, D., Grebel, E.K., Ferguson, Annette M. N., Cole, A. A., Koch, Andreas, Rejkuba, M., Da Costa, G., Jerjen, H., Crnojevic, D., Grebel, E.K., Ferguson, Annette M. N., Cole, A. A., Koch, Andreas, Rejkuba, M., Da Costa, G., and Jerjen, H.
Published: 2011

43. Spectroscopic versus photometric metallicities:Milky Way dwarf spheroidal companions as a test case

Author: Lianou, S., Grebel, E.K., Koch, Andreas, Lianou, S., Grebel, E.K., and Koch, Andreas
Abstract: Aims. The method of deriving photometric metallicities using red giant branch stars is applied to resolved stellar populations under the common assumption that they mainly consist of single-age old stellar populations. We explore the effect of the presence of mixed-age stellar populations on deriving photometric metallicities. Methods. We use photometric data sets for the five Galactic dwarf spheroidals Sculptor, Sextans, Carina, Fornax, and Leo II in order to derive their photometric metallicity distribution functions from their resolved red giant branches using isochrones of the Dartmouth Stellar Evolutionary Database. We compare the photometric metallicities with published spectroscopic metallicities based on the analysis of the near-infrared Ca triplet (Ca T), both on the metallicity scale of Carretta & Gratton and on the scale defined by the Dartmouth isochrones. In addition, we compare the photometric metallicities with published spectroscopic metallicities based on spectral synthesis and medium-resolution spectroscopy, and on high resolution spectra where available. Results. The mean properties of the spectroscopic and photometric metallicity samples are comparable within the intrinsic scatter of each method although the mean metallicities of dSphs with pronounced intermediate-age population fractions may be underestimated by the photometric method by up to a few tenths of dex in [Fe/H]. The star-by-star differences of the spectroscopic minus the photometric metallicities show a wide range of values along the fiducial spectroscopic metallicity range, with the tendency to have systematically lower photometric metallicities for those dwarf spheroidals with a higher fraction of intermediate-age populations. Such discrepancies persist even in the case of the purely old Sculptor dSph, where one would naïvely expect a very good match when comparing with medium or low resolution metallicity measurements. Overall, the agreement between Ca T metallicities and photomet
Published: 2011

44. M 81 group dSphs:metallicity distribution functions and gradients

Author: Lianou, S., Grebel, E.K., Koch, Andreas, Lianou, S., Grebel, E.K., and Koch, Andreas
Abstract: We summarize our results on the photometric metallicities and on the presence of metallicity gradients for nine M 81 group dSphs. The majority of our studied dSphs contains a significant fraction of intermediate–age stellar populations, which we consider as a function of the deprojected distance from the dominant galaxy of the group.
Published: 2011

45. Dwarf spheroidals in the M81 Group:metallicity distribution functions and population gradients

Author: Lianou, S., Grebel, E.K., Koch, Andreas, Lianou, S., Grebel, E.K., and Koch, Andreas
Abstract: Aims. We study the dwarf spheroidal galaxies in the nearby M 81 group in order to construct their photometric metallicity distributions and to investigate the potential presence of population gradients. We select all the dwarf spheroidals with available Hubble Space Telescope / Advanced Camera for Surveys archival observations, nine in total. Methods. We interpolate isochrones so as to assign a photometric metallicity to each star within a selection box in the color-magnitude diagram of each dwarf galaxy. We assume that the dwarf spheroidals contain mainly an old stellar population. In order to search for metallicity gradients, we examine the spatial distribution of two stellar populations that we separate according to their metallicities. Results. As a result, we present the photometric metallicity distribution functions, the cumulative histograms and smoothed density maps of the metal-poor and metal-rich stars as well as of the intermediate-age stars. Conclusions. From our photometric data we find that all the dwarf spheroidals show a wide range in metallicities, with mean values that are typical for old and metal-poor systems, with the exception of one dwarf spheroidal, namely IKN. Some of our dwarf spheroidals exhibit characteristics of transition-type dwarfs. Compared to the Local Group transition type dwarfs, the M 81 group ones appear to have mean metallicity values slightly more metal-rich at a given luminosity. All the dwarf spheroidals considered here appear to exhibit either population gradients or spatial variations in the centroids of their metal-poor and metal-rich population. In addition, there are luminous AGB stars detected in all of them with spatial distributions suggesting that they are well mixed with the old stars.
Published: 2010

46. A Roadmap for Delivering the Promise of Gaia

Author: Andersen, J., Prusti, T., Aerts, C.C., Grebel, E.K., Jordi, C., Klioner, S.A., Lindegren, L., Mignard, F., Randich, S., Walton, N.A., Andersen, J., Prusti, T., Aerts, C.C., Grebel, E.K., Jordi, C., Klioner, S.A., Lindegren, L., Mignard, F., Randich, S., and Walton, N.A.
Abstract: IAU Symposium, Contains fulltext : 76107.pdf (publisher's version ) (Closed access)
Published: 2009

47. A new low mass for the Hercules dSph:the end of a common mass scale for the dwarfs?

Author: Adén, D., Wilkinson, M. I., Read, J. I., Feltzing, S., Koch, Andreas, Gilmore, G. F., Grebel, E.K., Lundström, I., Adén, D., Wilkinson, M. I., Read, J. I., Feltzing, S., Koch, Andreas, Gilmore, G. F., Grebel, E.K., and Lundström, I.
Abstract: We present a new mass estimate for the Hercules dwarf spheroidal (dSph) galaxy, based on the revised velocity dispersion obtained by Adén et al. The removal of a significant foreground contamination using newly acquired Strömgren photometry has resulted in a reduced velocity dispersion. Using this new velocity dispersion of 3.72 ± 0.91 km s-1, we find a mass of M 300 = 1.9+1.1 –0.8 × 106 M ☉ within the central 300 pc, which is also the half-light radius, and a mass of M 433 = 3.7+2.2 –1.6 × 106 M ☉ within the reach of our data to 433 pc, significantly lower than previous estimates. We derive an overall mass-to-light ratio of M 433/L = 103+83 –48[M ☉/L ☉]. Our mass estimate calls into question recent claims of a common mass scale for dSph galaxies. Additionally, we find tentative evidence for a velocity gradient in our kinematic data of 16 ± 3 km s–1 kpc–1, and evidence of an asymmetric extension in the light distribution at ~0.5 kpc. We explore the possibility that these features are due to tidal interactions with the Milky Way. We show that there is a self-consistent model in which Hercules has an assumed tidal radius of rt = 485 pc, an orbital pericenter of rp = 18.5 ± 5 kpc, and a mass within rt of $M_{{\rm tid},r_t}=5.2_{-2.7}^{+2.7} \times 10^6\,M_\odot$. Proper motions are required to test this model. Although we cannot exclude models in which Hercules contains no dark matter, we argue that Hercules is more likely to be a dark-matter-dominated system that is currently experiencing some tidal disturbance of its outer parts.
Published: 2009

48. Kinematic subpopulations in dwarf spheroidal galaxies

Author: Ural, Uğur, Wilkinson, Mark I., Koch, Andreas, Gilmore, Gerard, Beers, Timothy C., Belokurov, V., Wyn Evans, N., Grebel, E.K., Vidrih, Simon, Zucker, D. B., Ural, Uğur, Wilkinson, Mark I., Koch, Andreas, Gilmore, Gerard, Beers, Timothy C., Belokurov, V., Wyn Evans, N., Grebel, E.K., Vidrih, Simon, and Zucker, D. B.
Abstract: We present new spectroscopic data for 26 stars in the recently discovered Canes Venatici I (CVn I) dwarf spheroidal galaxy, obtained with the Gemini Multi-Object Spectrograph North (GMOS-N) on the Gemini North telescope. We use these data to investigate the recent claim of the presence of two dynamically inconsistent stellar populations in this system. While we find no evidence for kinematically distinct subpopulations in our sample, we also show that the available kinematic data set in CVnI is likely too small to draw robust conclusions about its subpopulations. We are, however, able to obtain a mass estimate for CVn I that is consistent with all available data, including previously published data. We discuss possible differences between our sample and the earlier data set, and study the general detectability of subpopulations in small kinematic samples. We conclude that, in the absence of additional supporting observational evidence (e.g. metallicity gradients), subpopulations in small kinematic samples (typically fewer than 100 stars) should be treated with caution, as their identification depends on multiple parameters and rarely produces a signal at a high confidence level. It is therefore essential to explicitly determine the statistical significance of any suggested subpopulation.
Published: 2009

49. Velocity and abundance precisions for future high-resolution spectroscopic surveys: A study for 4MOST

Author: Caffau, E., primary, Koch, A., additional, Sbordone, L., additional, Sartoretti, P., additional, Hansen, C.J., additional, Royer, F., additional, Leclerc, N., additional, Bonifacio, P., additional, Christlieb, N., additional, Ludwig, H.-G., additional, Grebel, E.K., additional, de Jong, R.S., additional, Chiappini, C., additional, Walcher, J., additional, Mignot, S., additional, Feltzing, S., additional, Cohen, M., additional, Minchev, I., additional, Helmi, A., additional, Piffl, T., additional, Depagne, E., additional, and Schnurr, O., additional
Published: 2013
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50. Further evidence of a merger origin for the thick disk:galactic stars along lines of sight to dwarf spheroidal galaxies

Author: Wyse, Rosemary F. G., Gilmore, Gerard, Norris, John, Wilkinson, Mark I., Kleyna, Jan, Koch, Andreas, Evans, N. W., Grebel, E.K., Wyse, Rosemary F. G., Gilmore, Gerard, Norris, John, Wilkinson, Mark I., Kleyna, Jan, Koch, Andreas, Evans, N. W., and Grebel, E.K.
Abstract: The history of the Milky Way is written in the properties of its stellar populations. Here we analyze stars observed as part of surveys of local dwarf spheroidal galaxies, but which from their kinematics are highly likely to be nonmembers. The selection function—designed to target metal-poor giants in the dwarf galaxies, at distances of ~100 kpc—includes F-M dwarfs in the Milky Way, at distances of up to several kiloparsecs. The stars whose motions are analyzed here lie in the cardinal directions of Galactic longitude l ~ 270° and l ~ 90°, where the radial velocity is sensitive to the orbital rotational velocity. We demonstrate that the faint F and G stars contain a significant population with Vphgr ~ 100 km s-1, similar to that found by a targeted, but limited in areal coverage, survey of thick disk and halo stars by Gilmore et al. This value of mean orbital rotation does not match either the canonical thick disk or the stellar halo. We argue that this population, detected at both l ~ 270° and l ~ 90°, has the expected properties of "satellite debris" in the thick disk-halo interface, which we interpret as remnants of the merger that heated a preexisting thin disk to form the thick disk.
Published: 2006

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