@article{3069321,
    title = "Observational hertzsprung-russell diagrams",
    author = "Babusiaux, C. and Van Leeuwen, F. and Barstow, M.A. and Jordi, C. and Vallenari, A. and Bossini, D. and Bressan, A. and Cantat-Gaudin, T. and Van Leeuwen, M. and Brown, A.G.A. and Prusti, T. and De Bruijne, J.H.J. and Bailer-Jones, C.A.L. and Biermann, M. and Evans, D.W. and Eyer, L. and Jansen, F. and Klioner, S.A. and Lammers, U. and Lindegren, L. and Luri, X. and Mignard, F. and Panem, C. and Pourbaix, D. and Randich, S. and Sartoretti, P. and Siddiqui, H.I. and Soubiran, C. and Walton, N.A. and Arenou, F. and Bastian, U. and Cropper, M. and Drimmel, R. and Katz, D. and Lattanzi, M.G. and Bakker, J. and Cacciari, C. and Castañeda, J. and Chaoul, L. and Cheek, N. and De Angeli, F. and Fabricius, C. and Guerra, R. and Holl, B. and Masana, E. and Messineo, R. and Mowlavi, N. and Nienartowicz, K. and Panuzzo, P. and Portell, J. and Riello, M. and Seabroke, G.M. and Tanga, P. and Thévenin, F. and Gracia-Abril, G. and Comoretto, G. and Garcia-Reinaldos, M. and Teyssier, D. and Altmann, M. and Andrae, R. and Audard, M. and Bellas-Velidis, I. and Benson, K. and Berthier, J. and Blomme, R. and Burgess, P. and Busso, G. and Carry, B. and Cellino, A. and Clementini, G. and Clotet, M. and Creevey, O. and Davidson, M. and De Ridder, J. and Delchambre, L. and Dell'Oro, A. and Ducourant, C. and Fernández-Hernández, J. and Fouesneau, M. and Frémat, Y. and Galluccio, L. and García-Torres, M. and González-Núñez, J. and González-Vidal, J.J. and Gosset, E. and Guy, L.P. and Halbwachs, J.-L. and Hambly, N.C. and Harrison, D.L. and Hernández, J. and Hestroffer, D. and Hodgkin, S.T. and Hutton, A. and Jasniewicz, G. and Jean-Antoine-Piccolo, A. and Jordan, S. and Korn, A.J. and Krone-Martins, A. and Lanzafame, A.C. and Lebzelter, T. and Löffler, W. and Manteiga, M. and Marrese, P.M. and Martín-Fleitas, J.M. and Moitinho, A. and Mora, A. and Muinonen, K. and Osinde, J. and Pancino, E. and Pauwels, T. and Petit, J.-M. and Recio-Blanco, A. and Richards, P.J. and Rimoldini, L. and Robin, A.C. and Sarro, L.M. and Siopis, C. and Smith, M. and Sozzetti, A. and Süveges, M. and Torra, J. and Van Reeven, W. and Abbas, U. and Abreu Aramburu, A. and Accart, S. and Aerts, C. and Altavilla, G. and Álvarez, M.A. and Alvarez, R. and Alves, J. and Anderson, R.I. and Andrei, A.H. and Anglada Varela, E. and Antiche, E. and Antoja, T. and Arcay, B. and Astraatmadja, T.L. and Bach, N. and Baker, S.G. and Balaguer-Núñez, L. and Balm, P. and Barache, C. and Barata, C. and Barbato, D. and Barblan, F. and Barklem, P.S. and Barrado, D. and Barros, M. and Bartholomé Muñoz, S. and Bassilana, J.-L. and Becciani, U. and Bellazzini, M. and Berihuete, A. and Bertone, S. and Bianchi, L. and Bienaymé, O. and Blanco-Cuaresma, S. and Boch, T. and Boeche, C. and Bombrun, A. and Borrachero, R. and Bouquillon, S. and Bourda, G. and Bragaglia, A. and Bramante, L. and Breddels, M.A. and Brouillet, N. and Brüsemeister, T. and Brugaletta, E. and Bucciarelli, B. and Burlacu, A. and Busonero, D. and Butkevich, A.G. and Buzzi, R. and Caffau, E. and Cancelliere, R. and Cannizzaro, G. and Carballo, R. and Carlucci, T. and Carrasco, J.M. and Casamiquela, L. and Castellani, M. and Castro-Ginard, A. and Charlot, P. and Chemin, L. and Chiavassa, A. and Cocozza, G. and Costigan, G. and Cowell, S. and Crifo, F. and Crosta, M. and Crowley, C. and Cuypersy, J. and Dafonte, C. and Damerdji, Y. and Dapergolas, A. and David, P. and David, M. and De Laverny, P. and De Luise, F. and De March, R. and De Martino, D. and De Souza, R. and De Torres, A. and Debosscher, J. and Del Pozo, E. and Delbo, M. and Delgado, A. and Delgado, H.E. and Diakite, S. and Diener, C. and Distefano, E. and Dolding, C. and Drazinos, P. and Durán, J. and Edvardsson, B. and Enke, H. and Eriksson, K. and Esquej, P. and Eynard Bontemps, G. and Fabre, C. and Fabrizio, M. and Faigler, S. and Falcão, A.J. and Farràs Casas, M. and Federici, L. and Fedorets, G. and Fernique, P. and Figueras, F. and Filippi, F. and Findeisen, K. and Fonti, A. and Fraile, E. and Fraser, M. and Frézouls, B. and Gai, M. and Galleti, S. and Garabato, D. and García-Sedano, F. and Garofalo, A. and Garralda, N. and Gavel, A. and Gavras, P. and Gerssen, J. and Geyer, R. and Giacobbe, P. and Gilmore, G. and Girona, S. and Giuffrida, G. and Glass, F. and Gomes, M. and Granvik, M. and Gueguen, A. and Guerrier, A. and Guiraud, J. and Gutiérrez-Sánchez, R. and Haigron, R. and Hatzidimitriou, D. and Hauser, M. and Haywood, M. and Heiter, U. and Helmi, A. and Heu, J. and Hilger, T. and Hobbs, D. and Hofmann, W. and Holland, G. and Huckle, H.E. and Hypki, A. and Icardi, V. and Janßen, K. and De Fombelle, G.J. and Jonker, P.G. and Juhász, Á.L. and Julbe, F. and Karampelas, A. and Kewley, A. and Klar, J. and Kochoska, A. and Kohley, R. and Kolenberg, K. and Kontizas, M. and Kontizas, E. and Koposov, S.E. and Kordopatis, G. and Kostrzewa-Rutkowska, Z. and Koubsky, P. and Lambert, S. and Lanza, A.F. and Lasne, Y. and Lavigne, J.-B. and Le Fustec, Y. and Le Poncin-Lafitte, C. and Lebreton, Y. and Leccia, S. and Leclerc, N. and Lecoeur-Taibi, I. and Lenhardt, H. and Leroux, F. and Liao, S. and Licata, E. and Lindstrøm, H.E.P. and Lister, T.A. and Livanou, E. and Lobel, A. and López, M. and Managau, S. and Mann, R.G. and Mantelet, G. and Marchal, O. and Marchant, J.M. and Marconi, M. and Marinoni, S. and Marschalkó, G. and Marshall, D.J. and Martino, M. and Marton, G. and Mary, N. and Massari, D. and Matijević, G. and Mazeh, T. and McMillan, P.J. and Messina, S. and Michalik, D. and Millar, N.R. and Molina, D. and Molinaro, R. and Molnár, L. and Montegriffo, P. and Mor, R. and Morbidelli, R. and Morel, T. and Morris, D. and Mulone, A.F. and Muraveva, T. and Musella, I. and Nelemans, G. and Nicastro, L. and Noval, L. and O'Mullane, W. and Ordénovic, C. and Ordóñez-Blanco, D. and Osborne, P. and Pagani, C. and Pagano, I. and Pailler, F. and Palacin, H. and Palaversa, L. and Panahi, A. and Pawlak, M. and Piersimoni, A.M. and Pineau, F.-X. and Plachy, E. and Plum, G. and Poggio, E. and Poujoulet, E. and Prša, A. and Pulone, L. and Racero, E. and Ragaini, S. and Rambaux, N. and Ramos-Lerate, M. and Regibo, S. and Reylé, C. and Riclet, F. and Ripepi, V. and Riva, A. and Rivard, A. and Rixon, G. and Roegiers, T. and Roelens, M. and Romero-Gómez, M. and Rowell, N. and Royer, F. and Ruiz-Dern, L. and Sadowski, G. and Sagristà Sellés, T. and Sahlmann, J. and Salgado, J. and Salguero, E. and Sanna, N. and Santana-Ros, T. and Sarasso, M. and Savietto, H. and Schultheis, M. and Sciacca, E. and Segol, M. and Segovia, J.C. and Ségransan, D. and Shih, I.-C. and Siltala, L. and Silva, A.F. and Smart, R.L. and Smith, K.W. and Solano, E. and Solitro, F. and Sordo, R. and Soria Nieto, S. and Souchay, J. and Spagna, A. and Spoto, F. and Stampa, U. and Steele, I.A. and Steidelmüller, H. and Stephenson, C.A. and Stoev, H. and Suess, F.F. and Surdej, J. and Szabados, L. and Szegedi-Elek, E. and Tapiador, D. and Taris, F. and Tauran, G. and Taylor, M.B. and Teixeira, R. and Terrett, D. and Teyssandier, P. and Thuillot, W. and Titarenko, A. and Torra Clotet, F. and Turon, C. and Ulla, A. and Utrilla, E. and Uzzi, S. and Vaillant, M. and Valentini, G. and Valette, V. and Van Elteren, A. and Van Hemelryck, E. and Vaschetto, M. and Vecchiato, A. and Veljanoski, J. and Viala, Y. and Vicente, D. and Vogt, S. and Von Essen, C. and Voss, H. and Votruba, V. and Voutsinas, S. and Walmsley, G. and Weiler, M. and Wertz, O. and Wevers, T. and Wyrzykowski, Ł. and Yoldas, A. and Žerjal, M. and Ziaeepour, H. and Zorec, J. and Zschocke, S. and Zucker, S. and Zurbach, C. and Zwitter, T.",
    journal = "Chinese Astronomy and Astrophysics",
    year = "2018",
    volume = "616",
    publisher = "EDP Sciences",
    issn = "0275-1062",
    doi = "10.1051/0004-6361/201832843",
    keywords = "Atomic physics;  Galaxies;  Geometrical optics;  Kinematics;  Photometry, Evolutionary aspects;  Evolutionary phasis;  Hertzsprung-Russell and C-M diagrams;  Hertzsprung-russell diagrams;  Parallaxes;  Solar neighborhood;  Stars: evolution;  Stellar populations, White dwarfs",
    abstract = "Context. Gaia Data Release 2 provides high-precision astrometry and three-band photometry for about 1.3 billion sources over the full sky. The precision, accuracy, and homogeneity of both astrometry and photometry are unprecedented. Aims. We highlight the power of the Gaia DR2 in studying many fine structures of the Hertzsprung-Russell diagram (HRD). Gaia allows us to present many different HRDs, depending in particular on stellar population selections. We do not aim here for completeness in terms of types of stars or stellar evolutionary aspects. Instead, we have chosen several illustrative examples. Methods. We describe some of the selections that can be made in Gaia DR2 to highlight the main structures of the Gaia HRDs. We select both field and cluster (open and globular) stars, compare the observations with previous classifications and with stellar evolutionary tracks, and we present variations of the Gaia HRD with age, metallicity, and kinematics. Late stages of stellar evolution such as hot subdwarfs, post-AGB stars, planetary nebulae, and white dwarfs are also analysed, as well as low-mass brown dwarf objects. Results. The Gaia HRDs are unprecedented in both precision and coverage of the various Milky Way stellar populations and stellar evolutionary phases. Many fine structures of the HRDs are presented. The clear split of the white dwarf sequence into hydrogen and helium white dwarfs is presented for the first time in an HRD. The relation between kinematics and the HRD is nicely illustrated. Two different populations in a classical kinematic selection of the halo are unambiguously identified in the HRD. Membership and mean parameters for a selected list of open clusters are provided. They allow drawing very detailed cluster sequences, highlighting fine structures, and providing extremely precise empirical isochrones that will lead to more insight in stellar physics. Conclusions. Gaia DR2 demonstrates the potential of combining precise astrometry and photometry for large samples for studies in stellar evolution and stellar population and opens an entire new area for HRD-based studies. © ESO 2018."
}