Examinando por Autor "Haywood, M."

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    Gaia Focused Product Release: Radial velocity time series of long-period variables
    (EDP Sciences, 2023-12) Trabucchi, M.; Mowlavi, N.; Lebzelter, T.; Lecoeur-Taibi, I.; Audard, M.; Eyer, L.; García-Lario, P.; Gavras, P.; Holl, B.; Jevardat De Fombelle, G.; Nienartowicz, K.; Rimoldini, L.; Sartoretti, P.; Blomme, R.; Frémat, Y.; Marchal, O.; Damerdji, Y.; Brown A.G.A.; Guerrier, A.; Panuzzo, P.; Katz, D.; Seabroke, G.M.; Benson, K.; Haigron, R.; Smith, M.; Lobel, A.; Vallenari, A.; Prusti, T.; De Bruijne, J.H.J.; Arenou, F.; Babusiaux, C.; Barbier, A.; Biermann, M.; Creevey, O.L.; Ducourant, C.; Evans, D.W.; Guerra, R.; Hutton, A.; Jordi, C.; Klioner, S.A.; Lammers, U.; Lindegren, L.; Luri, X.; Mignard, F.; Randich, S.; Smiljanic, R.; Tanga, P.; Walton, N.A.; Bailer-Jones, C.A.L.; Bastian, U.; Cropper, M.; Drimmel, R.; Lattanzi, M.G.; Soubiran, C.; Van Leeuwen, F.; Bakker, J.; Castañeda, J.; De Angeli, F.; Fabricius, C.; Fouesneau, M.; Galluccio, L.; Masana, E.; Messineo, R.; Nicolas, C.; Pailler, F.; Riclet, F.; Roux, W.; Sordo, R.; Thévenin, F.; Gracia-Abril G.; Portell, J.; Teyssier, D.; Altmann, M.; Berthier, J; Burgess, P.W.; Busonero, D.; Busso, G.; Cánovas, H.; Carry, B.; Cheek, N.; Clementini, G.; Davidson, M.; De Teodoro, P.; Delchambre, L.; Dell'oro, A.; Fraile Garcia, E.; Garabato, D.; Garralda Torres, N.; Hambly, N.C.; Harrison, D.L.; Hatzidimitriou, D.; Hernández, J.; Hodgkin, S.T.; Jamal, S.; Jordan, S.; Krone-Martins, A.; Lanzafame, A.C.; Löffler, W.; Lorca, A.; Marrese, P.M.; Moitinho, A.; Muinonen, K.; Nuñez Campos, M.; Oreshina-Slezak, I.; Osborne, P.; Pancino, E.; Pauwels, T.; Recio-Blanco, A.; Riello, M.; Robin, A.C.; Roegiers, T.; Sarro, L.M.; Schultheis, M.; Siopis, C.; Siopis, C.; Sozzetti, A.; Utrilla, E.; Van Leeuwen, M.; Weingrill, K.; Abbas, U.; Ábrahám, P.; Abreu Aramburu, A.; Aerts , C.; Altavilla, G.; Álvarez, M.A.; Alves, J.; Anders, F.; Anderson, R.I.; Antoja, T.; Baines, D.; Baker, S.G.; Balog, Z.; Barache, C; Barbato, D.; Barros, M.; Barstow, M.A.; Bartolomé, S.; Bashi, D.; Bauchet, N.; Baudeau, N.; Becciani, U.; Bedin, L.R.; Bellas-Velidis, I.; Bellazzini, M.; Beordo, W.; Berihuete, A.; Bernet, M.; Bertolotto, C.; Bertone, S.; Bianchi, L.; Binnenfeld, A.; Blazere, A.; Boch, T.; Bombrun, A.; Bouquillon, S.; Bragaglia, A.; Braine, J.; Bramante, L.; Breedt, E.; Bressan, A.; Brouillet, N.; Brugaletta, E.; Bucciarelli, B.; Butkevich, A.G.; Buzzi, R.; Caffau, E.; Cancelliere, R.; Cannizzo, S.; Carballo, R.; Carlucci, T.; Carnerero, M.I.; Carrasco, J.M.; Carretero, J.; Carton, S.; Casamiquela, L.; Castellani, M.; Castro-Ginard, A.; Cesare, V.; Charlot, P.; Chemin, L.; Chiaramida, V.; Chiavassa, A.; Chornay, N.; Collins, R.; Contursi, G.; Cooper, W.J.; Cornez, T.; Crosta, M.; Crowley, C.; Dafonte, C.; David, M.; De Laverny, P.; De Luise, F.; De March, R.; De Ridder, J.; De Souza, R.; De Torres A.; Del Peloso, E.F.; Delbo, M.; Delgado, A.; Dharmawardena, T.E.; Diakite, S.; Diener, C.; Distefano, E.; Dolding, C.; Dsilva, K.; Durán, J.; Enke, H.; Esquej, P.; Fabre, C.; Fabrizio, M.; Faigler, S.; Fatović, M.; Fedorets, G.; Fernández-Hernández, J.; Fernique, P.; Figueras, F.; Fournier, Y.; Fouron, C.; Gai, M.; Galinier, M.; Garcia-Gutierrez, A.; García-Torres, M.; Garofalo, A.; Gerlach, E.; Geyer, R.; Giacobbe, P.; Gilmore, G.; Girona, S.; Giuffrida, G.; Gomel, R.; Gomez, A.; González-Núñez, J.; González-Santamaría, I.; Gosset, E.; Granvik, M.; Gregori Barrera, V.; Gutiérrez-Sánchez, R.; Haywood, M.; Helmer, A.; Helmi, A.; Henares, K.; Hidalgo, S.L.; Hilger, T.; Hobbs, D.; Hottier, C.; Huckle, H.E.; Jabłońska, M.; Jansen, F.; Jiménez-Arranz, Ó.; Juaristi Campillo, J.; Khanna, S.; Kordopatis, G.; Kóspál, Á.; Kostrzewa-Rutkowska, Z.; Kun, M.; Lambert, S.; Lanza, A.F.; Le Campion, J.-F.; Lebreton, Y.; Leccia, S.; Lecoutre, G.; Liao, S.; Liberato, L.; Licata, E.; Lindstrøm, H.E.P.; Lister, T.A.; Livanou, E.; Loup, C.; Mahy, L.; Mann, R.G.; Manteiga, M.; Marchant, J.M.; Marconi, M.; Marín Pina, D.; Marinoni, S.; Marshall, D.J.; Martín Lozano. J.; Martín-Fleitas, J.M.; Marton, G.; Mary, N.; Masip, A.; Massari, D.; Mastrobuono-Battisti, A.; Mazeh, T.; McMillan, P.J.; Meichsner, J.; Messina, S.; Michalik , D.; Millar, N.R.; Mints, A.; Molina, D.; Molinaro, R.; Molnár, L.; Monari, G.; Monguió, M.; Montegriffo, P.; Montero, A.; Mor, R.; Mora, A.; Morbidelli, R.; Morel, T.; Morris, D.; Munoz, D.; Muraveva, T.; Murphy, C.P.; Musella, I.; Nagy, Z.; Nieto, S.; Noval, L.; Ogden, A.; Ordenovic, C.; Pagani, C.; Pagano, I.; Palaversa, L.; Palicio, P.A.; Pallas-Quintela, L.; Panahi, A.; Panem, C.; Payne-Wardenaar, S.; Pegoraro, L.; Penttilä, A.; Pesciullesi, P.; Piersimoni, A.M.; Pinamonti, M.; Pineau, F.-X.; Plachy, E.; Plum, G.; Poggio, E.; Pourbaix, D.; Prša, A.; Pulone, L.; Racero, E.; Rainer, M.; Raiteri, C.M.; Ramos, P.; Ramos-Lerate, M.; Ratajczak, M.; Re Fiorentin, P.; Regibo, S.; Reylé, C.; Ripepi, V.; Riva, A.; Rix H.-W.; Rixon, G.; Robichon, N.; Robin, C.; Romero-Gómez, M.; Rowell, N.; Royer, F.; Ruz Mieres, D.; Rybicki, K.A.; Sadowski, G.; Sáez Núñez, A.; Sagristà Sellés, A.; Sahlmann, J.; Sanchez Gimenez, V.; Sanna, N.; Santoveña, R.; Sarasso, M.; Sarrate Riera, C.; Sciacca, E.; Segovia, J.C.; Ségransan, D.; Shahaf, S.; Siebert, A.; Siltala, L.; Slezak, E.; Smart, R.L.; Snaith, O.N.; Solano, E.; Solitro, F.; Souami, D.; Souchay, J.; Spina, L.; Spitoni, E.; Spoto, F.; Squillante, L.A.; Steele, I.A.; Steidelmüller, H.; Surdej, J.; Szabados, L.; Taris, F.; Taylor, M.B.; Teixeira, R.; Tisanić, K.; Tolomei, L.; Torra, F.; Torralba, Elipe G.; Tsantaki, M.; Ulla, A.; Unger, N.; Vanel, O.; Vecchiato, A.; Vicente, D.; Voutsinas, S.; Weiler, M.; Wyrzykowski, Ł.; Zhao, H.; Zorec, J.; Zwitter, T.; Balaguer-Nunez, L.; Leclerc, N.; Morgenthaler, S.; Robert, G.; Zucker, S.
    Context. The third Gaia Data Release (DR3) provided photometric time series of more than 2 million long-period variable (LPV) candidates. Anticipating the publication of full radial-velocity data planned with Data Release 4, this Focused Product Release (FPR) provides radial-velocity time series for a selection of LPV candidates with high-quality observations. Aims. We describe the production and content of the Gaia catalog of LPV radial-velocity time series, and the methods used to compute the variability parameters published as part of the Gaia FPR. Methods. Starting from the DR3 catalog of LPV candidates, we applied several filters to construct a sample of sources with high-quality radial-velocity measurements. We modeled their radial-velocity and photometric time series to derive their periods and amplitudes, and further refined the sample by requiring compatibility between the radial-velocity period and at least one of the G, GBP, or GRP photometric periods. Results. The catalog includes radial-velocity time series and variability parameters for 9614 sources in the magnitude range 6 ≲ G/mag ≲ 14, including a flagged top-quality subsample of 6093 stars whose radial-velocity periods are fully compatible with the values derived from the G, GBP, and GRP photometric time series. The radial-velocity time series contain a mean of 24 measurements per source taken unevenly over a duration of about three years. We identify the great majority of the sources (88%) as genuine LPV candidates, with about half of them showing a pulsation period and the other half displaying a long secondary period. The remaining 12% of the catalog consists of candidate ellipsoidal binaries. Quality checks against radial velocities available in the literature show excellent agreement. We provide some illustrative examples and cautionary remarks. Conclusions. The publication of radial-velocity time series for almost ten thousand LPV candidates constitutes, by far, the largest such database available to date in the literature. The availability of simultaneous photometric measurements gives a unique added value to the Gaia catalog. © The Authors 2023.
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    High-speed stars: Galactic hitchhikers
    (EDP Sciences, 2020-06) Caffau, E.; Monaco, L.; Bonifacio, P.; Sbordone, L.; Haywood, M.; Spite, M.; Di Matteo, P.; Spite, F.; Mucciarelli, A.; François, P.; Matas Pinto, A.M.
    Context. The search for stars born in the very early stages of the Milky Way star formation history is of paramount importance in the study of the early Universe since their chemistry carries irreplaceable information on the conditions in which early star formation and galaxy buildup took place. The search for these objects has generally taken the form of expensive surveys for faint extremely metal-poor stars, the most obvious but not the only candidates to a very early formation. Aims. Thanks to Gaia DR2 radial velocities and proper motions, we identified 72 bright cool stars displaying heliocentric transverse velocities in excess of 500 km s-1. These objects are most likely members of extreme outer-halo populations, either formed in the early Milky Way build-up or accreted from since-destroyed self-gravitating stellar systems. Methods. We analysed low-resolution FORS spectra of the 72 stars in the sample and derived the abundances of a few elements. Despite the large uncertainties on the radial velocity determination, we derived reliable orbital parameters for these objects. Results. The stars analysed are mainly slightly metal poor, with a few very metal-poor stars. Their chemical composition is much more homogeneous than expected. All the stars have very eccentric halo orbits, some extending well beyond the expected dimension of the Milky Way. Conclusions. These stars can be the result of a disrupted small galaxy or they could have been globular cluster members. Age estimates suggest that some of them are evolved blue stragglers, now on the subgiant or asymptotic giant branches. © E. Caffau et al. 2020.
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    TOPoS: VI. The metal-weak tail of the metallicity distribution functions of the Milky Way and the Gaia -Sausage-Enceladus structure
    (EDP Sciences, 2021-07) Bonifacio, P.; Monaco, L; Salvadori, S; Caffau, E.; Spite, M; Sbordone, L.; Spite, F.; Ludwig, H.-G; DI Matteo, P.; Haywood, M.; François, P.; Koch-Hansen, A.J
    Context. The goal of the Turn-Off Primordial Stars survey (TOPoS) project is to find and analyse turn-off (TO) stars of extremely low metallicity. To select the targets for spectroscopic follow-up at high spectral resolution, we relied on low-resolution spectra from the Sloan Digital Sky Survey (SDSS). Aims. In this paper, we use the metallicity estimates we obtained from our analysis of the SDSS spectra to construct the metallicity distribution function (MDF) of the Milky Way, with special emphasis on its metal-weak tail. The goal is to provide the underlying distribution out of which the TOPoS sample was extracted. Methods. We made use of SDSS photometry, Gaia photometry, and distance estimates derived from the Gaia parallaxes to derive a metallicity estimate for a large sample of over 24 million TO stars. This sample was used to derive the metallicity bias of the sample for which SDSS spectra are available. Results. We determined that the spectroscopic sample is strongly biased in favour of metal-poor stars, as intended. A comparison with the unbiased photometric sample allows us to correct for the selection bias. We selected a sub-sample of stars with reliable parallaxes for which we combined the SDSS radial velocities with Gaia proper motions and parallaxes to compute actions and orbital parameters in the Galactic potential. This allowed us to characterise the stars dynamically, and in particular to select a sub-sample that belongs to the Gaia-Sausage-Enceladus (GSE) accretion event. We are thus also able to provide the MDF of GSE. Conclusions. The metal-weak tail derived in our study is very similar to that derived in the H3 survey and in the Hamburg/ESO Survey. This allows us to average the three MDFs and provide an error bar for each metallicity bin. Inasmuch as the GSE structure is representative of the progenitor galaxy that collided with the Milky Way, that galaxy appears to be strongly deficient in metal-poor stars compared to the Milky Way, suggesting that the metal-weak tail of the latter has been largely formed by accretion of low-mass galaxies rather than massive galaxies, such as the GSE progenitor. © P. Bonifacio et al. 2021.