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Author: Caffau, E. × Author: Chemin, L. × DDC: 520 × Publisher: Les Ulis : EDP Sciences ×

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    Gaia Early Data Release 3: The celestial reference frame (Gaia-CRF3)
    (Les Ulis : EDP Sciences, 2022) Klioner, S.A.; Lindegren, L.; Mignard, F.; Hernández, J.; Ramos-Lerate, M.; Bastian, U.; Biermann, M.; Bombrun, A.; De Torres, A.; Gerlach, E.; Geyer, R.; Fraile, E.; Garabato, D.; García-Lario, P.; Gosset, E.; Haigron, R.; Halbwachs, J.-L.; Hambly, N.C.; Harrison, D.L.; Hestroffer, D.; Hodgkin, S.T.; Hilger, T.; Holl, B.; Janben, K.; Jevardat De Fombelle, G.; Jordan, S.; Krone-Martins, A.; Lanzafame, A.C.; Löffler, W.; Marchal, O.; Marrese, P.M.; Moitinho, A.; Hobbs, D.; Muinonen, K.; Osborne, P.; Pancino, E.; Pauwels, T.; Recio-Blanco, A.; Reylé, C.; Riello, M.; Rimoldini, L.; Roegiers, T.; Rybizki, J.; Lammers, U.L.; Sarro, L.M.; Siopis, C.; Smith, M.; Sozzetti, A.; Utrilla, E.; Van Leeuwen, M.; Abbas, U.; Ábrahám, P.; Abreu Aramburu, A.; Aerts, C.; McMillan, P.J.; Aguado, J.J.; Ajaj, M.; Aldea-Montero, F.; Altavilla, G.; Álvarez, M.A.; Alves, J.; Anderson, R.I.; Anglada Varela, E.; Antoja, T.; Baines, D.; Steidelmüller, H.; Baker, S.G.; Balaguer-Núñez, L.; Balbinot, E.; Balog, Z.; Barache, C.; Barbato, D.; Barros, M.; Barstow, M.A.; Bassilana, J.-L.; Bauchet, N.; Teyssier, D.; Becciani, U.; Bellazzini, M.; Berihuete, A.; Bertone, S.; Bianchi, L.; Binnenfeld, A.; Blanco-Cuaresma, S.; Boch, T.; Bossini, D.; Bouquillon, S.; Raiteri, C.M.; Bragaglia, A.; Bramante, L.; Breedt, E.; Bressan, A.; Brouillet, N.; Brugaletta, E.; Bucciarelli, B.; Burlacu, A.; Butkevich, A.G.; Buzzi, R.; Bartolomé, S.; Caffau, E.; Cancelliere, R.; Cantat-Gaudin, T.; Carballo, R.; Carlucci, T.; Carnerero, M.I.; Carrasco, J.M.; Casamiquela, L.; Castellani, M.; Castro-Ginard, A.; Bernet, M.; Chaoul, L.; Charlot, P.; Chemin, L.; Chiaramida, V.; Chiavassa, A.; Chornay, N.; Comoretto, G.; Contursi, G.; Cooper, W.J.; Cornez, T.; Castañeda, J.; Cowell, S.; Crifo, F.; Cropper, M.; Crosta, M.; Crowley, C.; Dafonte, C.; Dapergolas, A.; David, P.; De Laverny, P.; De Luise, F.; Clotet, M.; De March, R.; De Ridder, J.; De Souza, R.; Del Peloso, E.F.; Del Pozo, E.; Delbo, M.; Delgado, A.; Delisle, J.-B.; Demouchy, C.; Dharmawardena, T.E.; Davidson, M.; Diakite, S.; Diener, C.; Distefano, E.; Dolding, C.; Enke, H.; Fabre, C.; Fabrizio, M.; Faigler, S.; Fedorets, G.; Fernique, P.; Fabricius, C.; Fienga, A.; Figueras, F.; Fournier, Y.; Fouron, C.; Fragkoudi, F.; Gai, M.; Garcia-Gutierrez, A.; Garcia-Reinaldos, M.; García-Torres, M.; Garofalo, A.; Garralda Torres, N.; Gavel, A.; Gavras, P.; Giacobbe, P.; Gilmore, G.; Girona, S.; Giuffrida, G.; Gomel, R.; Gomez, A.; González-Núñez, J.; González-Santamaría, I.; González-Vidal, J.J.; Granvik, M.; Guillout, P.; Guiraud, J.; Gutiérrez-Sánchez, R.; Guy, L.P.; Hatzidimitriou, D.; Hauser, M.; Haywood, M.; Helmer, A.; Helmi, A.; Portell, J.; Sarmiento, M.H.; Hidalgo, S.L.; Hładczuk, N.; Holland, G.; Huckle, H.E.; Jardine, K.; Jasniewicz, G.; Jean-Antoine Piccolo, A.; Jiménez-Arranz, O.; Juaristi Campillo, J.; Rowell, N.; Julbe, F.; Karbevska, L.; Kervella, P.; Khanna, S.; Kordopatis, G.; Korn, A.J.; Kóspál, A.; Kostrzewa-Rutkowska, Z.; Kruszyńska, K.; Kun, M.; Torra, F.; Laizeau, P.; Lambert, S.; Lanza, A.F.; Lasne, Y.; Le Campion, J.-F.; Lebreton, Y.; Lebzelter, T.; Leccia, S.; Leclerc, N.; Lecoeur-Taibi, I.; Torra, J.; Liao, S.; Licata, E.L.; Lindstrøm, H.E.P.; Lister, T.A.; Livanou, E.; Lobel, A.; Lorca, A.; Loup, C.; Madrero Pardo, P.; Magdaleno Romeo, A.; Brown, A.G.A.; Managau, S.; Mann, R.G.; Manteiga, M.; Marchant, J.M.; Marconi, M.; Marcos, J.; Santos, M. M. S. Marcos; Marín Pina, D.; Marinoni, S.; Marocco, F.; Vallenari, A.; Marshall, D.J.; Polo, L. Martin; Martín-Fleitas, J.M.; Marton, G.; Mary, N.; Masip, A.; Massari, D.; Mastrobuono-Battisti, A.; Mazeh, T.; Messina, S.; Prusti, T.; Michalik, D.; Millar, N.R.; Mints, A.; Molina, D.; Molinaro, R.; Molnár, L.; Monari, G.; Monguió, M.; Montegriffo, P.; Montero, A.; De Bruijne, J.H.J.; Mor, R.; Mora, A.; Morbidelli, R.; Morel, T.; Morris, D.; Muraveva, T.; Murphy, C.P.; Musella, I.; Nagy, Z.; Noval, L.; Arenou, F.; Ocaña, F.; Ogden, A.; Ordenovic, C.; Osinde, J.O.; Pagani, C.; Pagano, I.; Palaversa, L.; Palicio, P.A.; Pallas-Quintela, L.; Panahi, A.; Babusiaux, C.; Payne-Wardenaar, S.; Peñalosa Esteller, X.; Penttilä, A.; Pichon, B.; Piersimoni, A.M.; Pineau, F.-X.; Plachy, E.; Plum, G.; Poggio, E.; Prša, A.; Creevey, O.L.; Pulone, L.; Racero, E.; Ragaini, S.; Rainer, M.; Rambaux, N.; Ramos, P.; Re Fiorentin, P.; Regibo, S.; Richards, P.J.; Diaz, C. Rios; Ducourant, C.; Ripepi, V.; Riva, A.; Rix, H.-W.; Rixon, G.; Robichon, N.; Robin, A.C.; Robin, C.; Roelens, M.; Rogues, H.R.O.; Rohrbasser, L.; Evans, D.W.; Romero-Gómez, M.; Royer, F.; Ruz Mieres, D.; Rybicki, K.A.; Sadowski, G.; Sáez Núñez, A.; Sagristà Sellés, A.; Sahlmann, J.; Salguero, E.; Samaras, N.; Eyer, L.; Sanchez Gimenez, V.; Sanna, N.; Santoveña, R.; Sarasso, M.; Schultheis, M.; Sciacca, E.; Segol, M.; Segovia, J.C.; Ségransan, D.; Semeux, D.; Guerra, R.; Shahaf, S.; Siddiqui, H.I.; Siebert, A.; Siltala, L.; Silvelo, A.; Slezak, E.; Slezak, I.; Smart, R.L.; Snaith, O.N.; Solano, E.; Hutton, A.; Solitro, F.; Souami, D.; Souchay, J.; Spagna, A.; Spina, L.; Spoto, F.; Steele, I.A.; Stephenson, C.A.; Süveges, M.; Surdej, J.; Jordi, C.; Szabados, L.; Szegedi-Elek, E.; Taris, F.; Taylor, M.B.; Teixeira, R.; Tolomei, L.; Tonello, N.; Torralba Elipe, G.; Trabucchi, M.; Tsounis, A.T.; Luri, X.; Turon, C.; Ulla, A.; Unger, N.; Vaillant, M.V.; Van Dillen, E.; Van Reeven, W.; Vanel, O.; Vecchiato, A.; Viala, Y.; Vicente, D.; Panem, C.; Voutsinas, S.; Weiler, M.; Wevers, T.; Wyrzykowski, L.; Yoldas, A.; Yvard, P.; Zhao, H.; Zorec, J.; Zucker, S.; Zwitter, T.; Pourbaix, D.; Randich, S.; Sartoretti, P.; Soubiran, C.; Tanga, P.; Walton, N.A.; Bailer-Jones, C.A.L.; Drimmel, R.; Jansen, F.; Katz, D.; Lattanzi, M.G.; Van Leeuwen, F.; Bakker, J.; Cacciari, C.; De Angeli, F.; Fouesneau, M.; Frémat, Y.; Galluccio, L.; Guerrier, A.; Heiter, U.; Masana, E.; Messineo, R.; Mowlavi, N.; Nicolas, C.; Nienartowicz, K.; Pailler, F.; Panuzzo, P.; Riclet, F.; Roux, W.; Seabroke, G.M.; Sordo, R.; Thévenin, F.; Gracia-Abril, G.; Altmann, M.; Andrae, R.; Audard, M.; Bellas-Velidis, I.; Benson, K.; Berthier, J.; Blomme, R.; Burgess, P.W.; Busonero, D.; Busso, G.; Cánovas, H.; Carry, B.; Cellino, A.; Cheek, N.; Clementini, G.; Damerdji, Y.; De Teodoro, P.; Nuñez Campos, M.; Delchambre, L.; Dell'Oro, A.; Esquej, P.; Fernández-Hernández, J.
    Context. Gaia-CRF3 is the celestial reference frame for positions and proper motions in the third release of data from the Gaia mission, Gaia DR3 (and for the early third release, Gaia EDR3, which contains identical astrometric results). The reference frame is defined by the positions and proper motions at epoch 2016.0 for a specific set of extragalactic sources in the (E)DR3 catalogue. Aims. We describe the construction of Gaia-CRF3 and its properties in terms of the distributions in magnitude, colour, and astrometric quality. Methods. Compact extragalactic sources in Gaia DR3 were identified by positional cross-matching with 17 external catalogues of quasi-stellar objects (QSO) and active galactic nuclei (AGN), followed by astrometric filtering designed to remove stellar contaminants. Selecting a clean sample was favoured over including a higher number of extragalactic sources. For the final sample, the random and systematic errors in the proper motions are analysed, as well as the radio-optical offsets in position for sources in the third realisation of the International Celestial Reference Frame (ICRF3). Results. Gaia-CRF3 comprises about 1.6 million QSO-like sources, of which 1.2 million have five-parameter astrometric solutions in Gaia DR3 and 0.4 million have six-parameter solutions. The sources span the magnitude range G = 13-21 with a peak density at 20.6 mag, at which the typical positional uncertainty is about 1 mas. The proper motions show systematic errors on the level of 12 μas yr-1 on angular scales greater than 15 deg. For the 3142 optical counterparts of ICRF3 sources in the S/X frequency bands, the median offset from the radio positions is about 0.5 mas, but it exceeds 4 mas in either coordinate for 127 sources. We outline the future of Gaia-CRF in the next Gaia data releases. Appendices give further details on the external catalogues used, how to extract information about the Gaia-CRF3 sources, potential (Galactic) confusion sources, and the estimation of the spin and orientation of an astrometric solution.
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    The Gaia RVS benchmark stars: I. Chemical inventory of the first sample of evolved stars and its Rb NLTE investigation
    (Les Ulis : EDP Sciences, 2021) Caffau, E.; Bonifacio, P.; Korotin, S.A.; François, P.; Lallement, R.; Matas Pinto, A.M.; Di Matteo, P.; Steffen, M.; Mucciarelli, A.; Katz, D.; Haywood, M.; Chemin, L.; Sartoretti, P.; Sbordone, L.; Andrievsky, S.M.; Kovtyukh, V.V.; Spite, M.; Spite, F.; Panuzzo, P.; Royer, F.; Thévenin, F.; Ludwig, H.-G.; Marchal, O.; Plum, G.
    Context. The Radial Velocity Spectrometer (RVS) on board the Gaia satellite is not provided with a wavelength calibration lamp. It uses its observations of stars with known radial velocity to derive the dispersion relation. To derive an accurate radial velocity calibration, a precise knowledge of the line spread function (LSF) of the RVS is necessary. Good-quality ground-based observations in the wavelength range of the RVS are highly desired to determine the LSF. Aims. Several radial velocity standard stars are available to the Gaia community. The highest possible number of calibrators will surely allow us to improve the accuracy of the radial velocity. Because the LSF may vary across the focal plane of the RVS, a large number of high-quality spectra for the LSF calibration may allow us to better sample the properties of the focal plane. Methods. We selected a sample of stars to be observed with UVES at the Very Large Telescope, in a setting including the wavelength range of RVS, that are bright enough to allow obtaining high-quality spectra in a short time. We also selected stars that lack chemical investigation in order to increase the sample of bright, close by stars with a complete chemical inventory. Results. We here present the chemical analysis of the first sample of 80 evolved stars. The quality of the spectra is very good, therefore we were able to derive abundances for 20 elements. The metallicity range spanned by the sample is about 1 dex, from slightly metal-poor to solar metallicity. We derived the Rb abundance for all stars and investigated departures from local thermodynamical equilibrium (NLTE) in the formation of its lines. Conclusions. The sample of spectra is of good quality, which is useful for a Gaia radial velocity calibration. The Rb NLTE effects in this stellar parameters range are small but sometimes non-negligible, especially for spectra of this good quality.