Examinando por Autor "Marocco, Federico"
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Publicación Near-infrared spectroscopic characterisation of Gaia ultra-cool dwarf candidates. Spectral types and peculiarities(EDP Sciences, 2024-04-30) Ravinet, Thomas; Reylé, Céline; Lagarde, Nadège; Burgasser, Adam J.; Smart, R. L.; Moya, Wisthon Aby Haro; Marocco, Federico; Scholz, Ralf; Cooper, W. J.; Cruz, Kelle; Fernández Trincado, José G.; Homeier, Derek; Sarro Baro, Luis Manuel; https://orcid.org/0000-0001-8652-2835; https://orcid.org/0000-0003-2258-2403; https://orcid.org/0000-0003-0108-3859; https://orcid.org/0000-0002-6523-9536; https://orcid.org/0000-0002-4424-4766; https://orcid.org/0000-0003-3642-6903; https://orcid.org/0000-0001-7519-1700; https://orcid.org/0000-0002-0894-9187; https://orcid.org/0000-0003-3501-8967; https://orcid.org/0000-0002-1821-0650; https://orcid.org/0000-0003-3526-5052; https://orcid.org/0000-0002-8546-9128Context. The local census of very low-mass stars and brown dwarfs is crucial to improving our understanding of the stellar-substellar transition and their formation history. These objects, known as ultra-cool dwarfs (UCDs), are essential targets for searches of potentially habitable planets. However, their detection poses a challenge because of their low luminosity. The Gaia survey has identified numerous new UCD candidates thanks to its large survey and precise astrometry. Aims. We aim to characterise 60 UCD candidates detected by Gaia in the solar neighbourhood with a spectroscopic follow-up to confirm that they are UCDs, as well as to identify peculiarities. Methods. We acquired the near-infrared (NIR) spectra of 60 objects using the SOFI spectrograph between 0.93 and 2.5 µm (R~ 600). We identified their spectral types using a template-matching method. Their binarity is studied using astrometry and spectral features. Results. We confirm that 60 objects in the sample have ultra-cool dwarf spectral types close to those expected from astrometry. Their NIR spectra reveal that seven objects could host an unresolved coolest companion and seven UCDs share the same proper motions as other stars. The characterisation of these UCDs is part of a coordinated effort to improve our understanding of the Solar neighbourhood.Publicación Ultracool dwarfs in Gaia DR3(EDP Sciences, 2023-01-26) Sarro Baro, Luis Manuel; Berihuete, Ángel; Smart, R. L.; Reylé, Céline; Barrado, David; Garcia Torres, Miguel; Cooper, W. J.; Jones, H. R. A.; Marocco, Federico; Creevey, Orlagh; Sordo, Rosanna; Bailer Jones, C. A. L.; Montegriffo, P.; Ruth Carballo; Andrae, Rene; Fouesneau, Morgan; Lanzafame, Alessandro; Pailler, Fred; Thévenin, F.; Lobel, A.; Delchambre, L.; Korn, Andreas J.; Recio Blanco, Alejandra; Schultheis, M.; Angeli, Francesca De; Brouillet, Nathalie; Casamiquela, Laia; Contursi, Gabriele; Laverny, P. de; Garcia Lario, Pedro; Kordopatis, G.; Lebreton, Y.; Livanou, E.; Lorca, Alejandro; Palicio, Pedro Alonso; Slezak Oreshina, I.; Contursi, Gabriele; Ulla, A.; Zhao, He; https://orcid.org/0000-0002-8589-4423; https://orcid.org/0000-0002-4424-4766; https://orcid.org/0000-0003-2258-2403; https://orcid.org/0000-0002-5971-9242; https://orcid.org/0000-0002-6867-7080; https://orcid.org/0000-0003-3501-8967; https://orcid.org/0000-0003-0433-3665; https://orcid.org/0000-0001-7519-1700; https://orcid.org/0000-0003-1853-6631; https://orcid.org/0000-0003-4979-0659; https://orcid.org/0000-0001-5013-5948; https://orcid.org/0000-0001-7412-2498; https://orcid.org/0000-0001-8006-6365; https://orcid.org/0000-0001-9256-5516; https://orcid.org/0000-0002-2697-3607; https://orcid.org/0000-0002-6855-2050; https://orcid.org/0000-0001-5030-019X; https://orcid.org/0000-0003-2559-408X; https://orcid.org/0000-0002-3881-6756; https://orcid.org/0000-0002-6590-1657; https://orcid.org/0000-0003-1879-0488; https://orcid.org/0000-0002-3274-7024; https://orcid.org/0000-0001-5238-8674; https://orcid.org/0000-0001-5370-1511; https://orcid.org/0000-0002-2817-4104; https://orcid.org/0000-0003-4039-8212; https://orcid.org/0000-0002-9035-3920; https://orcid.org/0000-0002-7985-250X; https://orcid.org/0000-0002-7432-8709; https://orcid.org/0000-0001-5370-1511; https://orcid.org/0000-0003-2645-6869Context. Previous Gaia data releases offered the opportunity to uncover ultracool dwarfs (UCDs) through astrometric, rather than purely photometric, selection. The most recent, the third data release (DR3), offers in addition the opportunity to use low-resolution spectra to refine and widen the selection. Aims. In this work we use the Gaia DR3 set of UCD candidates and complement the Gaia spectrophotometry with additional photometry in order to characterise the global properties of the set. This includes the inference of the distances, their locus in the Gaia colour-absolute magnitude diagram, and the (biased through selection) luminosity function at the faint end of the main sequence. We study the overall changes in the Gaia RP spectra as a function of spectral type. We study the UCDs in binary systems, we attempt to identify low-mass members of nearby young associations, star-forming regions, and clusters, and we analyse their variability properties. Methods. We used a forward model and the Bayesian inference framework to produce posterior probabilities for the distribution parameters and a calibration of the colour index as a function of the absolute magnitude in the form of a Gaussian process. Additionally, we applied the hierarchical mode association clustering (HMAC) unsupervised classification algorithm for the detection and characterisation of overdensities in the space of celestial coordinates, projected velocities, and parallaxes. Results. We detect 57 young, kinematically homogeneous groups, some of which are identified as well-known star-forming regions, associations, and clusters of different ages. We find that the primary members of the 880 binary systems with a UCD belong to the thin and thick disc components of the Milky Way. We identify 1109 variable UCDs using the variability tables in the Gaia archive, 728 of which belong to the star-forming regions defined by HMAC. We define two groups of variable UCDs with extreme bright or faint outliers. Conclusions. The set of sources identified as UCDs in the Gaia archive contains a wealth of information that will require focused follow-up studies and observations. It will help advance our understanding of the nature of the faint end of the main sequence and the stellar-substellar transition.