Examinando por Autor "Casamiquela, Laia"

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  • Miniatura
    Publicación
    Kalkayotl: A cluster distance inference code
    (EDP Sciences, 2020-11-24) Olivares Romero, Javier; Sarro Baro, Luis Manuel; Bouy, Hervé; Miret Roig, Nuria; Casamiquela, Laia; Galli, P. A. B.; Berihuete, Ángel; Tarricq, Y.; https://orcid.org/0000-0002-7084-487X; https://orcid.org/0000-0001-5292-0421; https://orcid.org/0000-0001-5238-8674; https://orcid.org/0000-0002-8589-4423
    Context. The high-precision parallax data of the Gaia mission allows for significant improvements in the distance determination to stellar clusters and their stars. In order to obtain accurate and precise distance determinations, systematics such as parallax spatial correlations need to be accounted for, especially with regard to stars in small sky regions. Aims. Our aim is to provide the astrophysical community with a free and open code designed to simultaneously infer cluster parameters (i.e., distance and size) and distances to the cluster stars using Gaia parallax measurements. The code includes cluster-oriented prior families and it is specifically designed to deal with the Gaia parallax spatial correlations. Methods. A Bayesian hierarchical model is created to allow for the inference of both the cluster parameters and distances to its stars. Results. Using synthetic data that mimics Gaia parallax uncertainties and spatial correlations, we observe that our cluster-oriented prior families result in distance estimates with smaller errors than those obtained with an exponentially decreasing space density prior. In addition, the treatment of the parallax spatial correlations minimizes errors in the estimated cluster size and stellar distances, and avoids the underestimation of uncertainties. Although neglecting the parallax spatial correlations has no impact on the accuracy of cluster distance determinations, it underestimates the uncertainties and may result in measurements that are incompatible with the true value (i.e., falling beyond the 2σ uncertainties). Conclusions. The combination of prior knowledge with the treatment of Gaia parallax spatial correlations produces accurate (error < 10%) and trustworthy estimates (i.e., true values contained within the 2σ uncertainties) of cluster distances for clusters up to ∼5 kpc, along with cluster sizes for clusters up to ∼1 kpc.
  • 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.