Proyecto de Investigación: AYA2015-69350-C3-1-P
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AYA2015-69350-C3-1-P
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J-PLUS: Discovery and characterisation of ultracool dwarfs using Virtual Observatory tools
(EDP Sciences, 2019-06-27) Martín, E. L.; Caballero, J. A.; Rodrigo, C.; Angulo, R. E.; Alcaniz, J. S.; Borges Fernandes, M.; Cenarro, A. J.; Cristóbal Hornillos, D.; Dupke, R. A.; Alfaro, E. J.; Ederoclite, A.; Jiménez Esteban, F. M.; Hernández Jiménez, J. A.; Hernández Monteagudo, C.; Lopes de Oliveira, R.; López Sanjuan, C.; Marín Franch, A.; Mendes de Oliveira, Claudia L.; Moles, M.; Orsi, Álvaro A.; Schmidtobreick, L.; Sobral, D.; Sodré, L.; Varela, J.; Vázquez Ramió, H.; Solano, Enrique; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Comisión Nacional de Investigación Científica y Tecnológica (CONICYT); European Research Council (ERC); Caballero, J. A. [https://orcid.org/0000-0002-7349-1387]; Jailson Souza de Alcaniz. [https://orcid.org/0000-0003-2441-1413]; Alfaro, Emilio J. [https://orcid.org/0000-0002-2234-7035]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. Ultracool dwarfs are objects with spectral types equal to or later than M7. Most of them have been discovered using wide-field imaging surveys. The Virtual Observatory has proven to be very useful for efficiently exploiting these astronomical resources.
Aims. We aim to validate a Virtual Observatory methodology designed to discover and characterise ultracool dwarfs in the J-PLUS photometric survey. J-PLUS is a multiband survey carried out with the wide-angle T80Cam optical camera mounted on the 0.83 m telescope JAST/T80 in the Observatorio Astrofísico de Javalambre. We make use of the Internal Data Release covering 528 deg2.
Methods. We complemented J-PLUS photometry with other catalogues in the optical and infrared using VOSA, a Virtual Observatory tool that estimates physical parameters from the spectral energy distribution fitting to collections of theoretical models. Objects identified as ultracool dwarfs were distinguished from background M giants and highly reddened stars using parallaxes and proper motions from Gaia DR2.
Results. We identify 559 ultracool dwarfs, ranging from i = 16.2 mag to i = 22.4 mag, of which 187 are candidate ultracool dwarfs not previously reported in the literature. This represents an increase in the number of known ultracool dwarfs of about 50% in the region of the sky we studied, particularly at the faint end of our sensitivity, which is interesting as reference for future wide and deep surveys such as Euclid. Three candidates are interesting targets for exoplanet surveys because of their proximity (distances less than 40 pc). We also analysed the kinematics of ultracool dwarfs in our catalogue and found evidence that it is consistent with a Galactic thin-disc population, except for six objects that might be members of the thick disc.
Conclusion. The results we obtained validate the proposed methodology, which will be used in future J-PLUS and J-PAS releases. Considering the region of the sky covered by the Internal Data Release used in this work, we estimate that 3000–3500 new ultracool dwarfs will be discovered at the end of the J-PLUS project.
Ultracool dwarfs in deep extragalactic surveys using the virtual observatory: ALHAMBRA and COSMOS
(Oxford Academics: Oxford University Press, 2021-02-01) Gálvez Ortiz, M. C.; Martín, E. L.; Gómez Muñoz, I. M.; Rodrigo, C.; Burgasser, A. J.; Lodieu, N.; Béjar, V. J. S.; Huélamo, N.; Morales Calderón, M.; Bouy, H.; Solano, Enrique; Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Ultracool dwarfs (UCDs) encompass a wide variety of compact stellar-like objects with spectra classified as late-M, L, T, and Y. Most of them have been discovered using wide-field imaging surveys. The Virtual Observatory (VO) has proven to be of great utility to efficiently exploit these astronomical resources. We aim to validate a VO methodology designed to discover and characterize UCDs in deep extragalactic surveys like Advance Large Homogeneous Area Medium-Band Redshift Astronomical (ALHAMBRA) and Cosmological Evolution Survey (COSMOS). Three complimentary searches based on parallaxes, proper motions and colours, respectively, were carried out. A total of 897 candidate UCDs were found, with only 16 previously reported in SIMBAD. Most of the new UCDs reported here are likely late-M and L dwarfs because of the limitations imposed by the utilization of optical (Gaia DR2 and r-band) data. We complement ALHAMBRA and COSMOS photometry with other catalogues in the optical and infrared using VOSA, a VO tool that estimates effective temperatures from the spectral energy distribution fitting to collections of theoretical models. The agreement between the number of UCDs found in the COSMOS field and theoretical estimations together with the low false-negative rate (known UCDs not discovered in our search) validates the methodology proposed in this work, which will be used in the forthcoming wide and deep surveys provided by the Euclid space mission. Simulations of Euclid number counts for UCDs detectable in different photometric passbands are presented for a wide survey area of 15 000 deg2, and the limitations of applicability of Euclid data to detect UCDs using the methods employed in this paper are discussed.
