Examinando por Autor "Lobel, A."

Mostrando 1 - 2 de 2
  • Miniatura
    Publicación
    Gaia Data Release 3. A golden sample of astrophysical parameters
    (EDP Sciences, 2023-06-16) Creevey, O. L.; Lobel, A.; Pancino, Elena; Sarro Baro, Luis Manuel
    Context. Gaia Data Release 3 (DR3) provides a wealth of new data products for the astronomical community to exploit, including astrophysical parameters for half a billion stars. In this work, we demonstrate the high quality of these data products and illustrate their use in different astrophysical contexts. Aims. We produce homogeneous samples of stars with high-quality astrophysical parameters by exploiting Gaia DR3, while focusing on many regimes across the Hertzsprung-Russell (HR) diagram; spectral types OBA, FGKM, and ultracool dwarfs (UCDs). We also focus on specific subsamples of particular interest to the community: solar analogues, carbon stars, and the Gaia spectrophotometric standard stars (SPSS). Methods. We query the astrophysical parameter tables along with other tables in Gaia DR3 to derive the samples of the stars of interest. We validate our results using the Gaia catalogue itself and by comparison with external data. Results. We produced six homogeneous samples of stars with high-quality astrophysical parameters across the HR diagram for the community to exploit. We first focus on three samples that span a large parameter space: young massive disc stars (OBA; about 3 Million), FGKM spectral type stars (about 3 Million), and UCDs (about 20 000). We provide these sources along with additional information (either a flag or complementary parameters) as tables that are made available in the Gaia archive. We also identify 15 740 bone fide carbon stars and 5863 solar analogues, and provide the first homogeneous set of stellar parameters of the SPSS sample. We demonstrate some applications of these samples in different astrophysical contexts. We use a subset of the OBA sample to illustrate its usefulness in analysing the Milky Way rotation curve. We then use the properties of the FGKM stars to analyse known exoplanet systems. We also analyse the ages of some unseen UCD-companions to the FGKM stars. We additionally predict the colours of the Sun in various passbands (Gaia, 2MASS, WISE) using the solar-analogue sample. Conclusions. Gaia DR3 contains a wealth of new high-quality astrophysical parameters for the community to exploit.
  • Miniatura
    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/0000-0003-2645-6869
    Context. 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.