Browsing by Author "Schoenell, W."

Now showing 1 - 6 of 6
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    CLASH : Accurate photometric redshifts with 14 HST bands in massive galaxy cluster cores
    (2017) Lazkoz, R.; Lemze, D.; Maoz, D.; Mercurio, A.; Meneghetti, M.; Merten, J.; Moustakas, L.; Nonino, M.; Orgaz, S.; Infante Lira, Leopoldo; Riess, A.; Rodney, S.; Sayers, J.; Umetsu, K.; Zheng, W.; Zitrin, A.; Molino, A.; Benítez, N.; Ascaso, B.; Coe, D.; Postman M.; Jouvel, S.; Host, O.; Lahav O.; Seitz, S.; Medezinski, E.; Rosati, P.; Schoenell, W.; Koekemoer, A.; Jiménez-Teja, Y.; Broadhurst, T.; Melchior, P.; Balestra, I.; Bartelmann, M.; Bouwens, R.; Bradley, L.; Czakon, N.; Donahue, M.; Ford, H.; Graur, O.; Graves, G.; Grillo, C.; Jha, S.; Kelson, D.
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    Galaxy clusters and groups in the ALHAMBRA survey
    (2015) Ascaso, B.; Benitez, N.; Fernandez-Soto, A.; Arnalte-Mur, P.; Lopez-Sanjuan, C.; Molino, A.; Schoenell, W.; Jimenez-Teja, Y.; Merson, A. I.; Infante Lira, Leopoldo; Díaz-Garcia, L. A.; Martınez, V. J.; Cenarro, A. J.; Dupke, R.; Marquez, I.; Masegosa, J.; Nieves-Seoane, L.; Povic, M.; Varela, J.; Huertas-Company, M.
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    Observations of the First Electromagnetic Counterpart to a Gravitational-wave Source by the TOROS Collaboration
    (2017) Díaz, Marco A.; Macri, L.; Lambas, D.; Oliveira, C.; Castellón, J.; Ribeiro, T.; Sánchez, B.; Schoenell, W.; Abramo, L.; Padilla, Nelson; Akras, S.; Alcaniz, J.; Artola, R.; Beroiz, M.; Bonoli, S.; Cabral, J.; Camuccio, R.; Castillo, M.; Chavushyan, V.; Coelho, P.; Colazo, C.
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    Stellar atmospheric parameters and chemical abundances of ∼5 million stars from S-PLUS multiband photometry
    (EDP SCIENCES S A, 2025) Ferreira Lopes, C. E.; Gutierrez-Soto, L. A.; S. Ferreira Alberice, V.; Monsalves, N.; Hazarika, D.; Catelan, Márcio; Placco, V. M.; Limberg, G.; Almeida-Fernandes, F.; Perottoni, H. D.; Smith Castelli, A. V.; Akras, S.; Alonso-Garcia, J.; Cordeiro, V.; Jaque Arancibia, M.; Daflon, S.; Dias, B.; Goncalves, D. R.; Machado-Pereira, E.; Lopes, A. R.; Bom, C. R.; Thom de Souza, R. C.; de Isidio, N. G.; Alvarez-Candal, A.; De Rossi, M. E.; Bonatto, C. J.; Cubillos Palma, B.; Borges Fernandes, M.; Humire, P. K.; Oliveira Schwarz, G. B.; Schoenell, W.; Kanaan, A.; Mendes de Oliveira, C.
    Context. The APOGEE, GALAH, and LAMOST spectroscopic surveys have substantially contributed to our understanding of the Milky Way by providing a wide range of stellar parameters and chemical abundances. Complementing these efforts, photometric surveys that include narrowband and medium-band filters, such as Southern Photometric Local Universe Survey (S-PLUS), provide a unique opportunity to estimate the atmospheric parameters and elemental abundances for a much larger number of sources, compared to spectroscopic surveys., Aims. Our aim is to establish methodologies for extracting stellar atmospheric parameters and selected chemical abundances from S-PLUS photometric data, which cover approximately 3000 square degrees, by applying seven narrowband and five broadband filters., Methods. We used all 66 S-PLUS colors to estimate parameters based on three different training samples from the LAMOST, APOGEE, and GALAH surveys, applying cost-sensitive neural network (NN) and random forest (RF) algorithms. We kept the stellar abundances that lacked corresponding absorption features in the S-PLUS filters to test for spurious correlations in our method. Furthermore, we evaluated the effectiveness of the NN and RF algorithms by using estimated T-eff and log g values as the input features to determine other stellar parameters and abundances. The NN approach consistently outperforms the RF technique on all parameters tested. Moreover, incorporating T-eff and log g leads to an improvement in the estimation accuracy by approximately 3%. We kept only parameters with a goodness-of-fit higher than 50%., Results. Our methodology allowed us to obtain reliable estimates for fundamental stellar parameters (T-eff, log g, and [Fe/H]) and elemental abundance ratios such as [alpha/Fe], [Al/Fe], [C/Fe], [Li/Fe], and [Mg/Fe] for approximately five million stars across the Milky Way, with a goodness-of-fit above 60%. We also obtained additional abundance ratios, including [Cu/Fe], [O/Fe], and [Si/Fe]. However, these ratios should be used cautiously due to their low accuracy or lack of a clear relationship with the S-PLUS filters. Validation of our estimations and methods was performed using star clusters, Transiting Exoplanet Survey Satellite (TESS) data and Javalambre Photometric Local Universe Survey (J-PLUS) photometry, further demonstrating the robustness and accuracy of our approach., Conclusions. By leveraging S-PLUS photometric data and advanced machine learning techniques, we have established a robust framework for extracting fundamental stellar parameters and chemical abundances from medium-band and narrowband photometric observations. This approach offers a cost-effective alternative to high-resolution spectroscopy. The estimated parameters hold significant potential for future studies, particularly when classifying objects within our Milky Way or gaining insights into its various stellar populations.
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    The ALHAMBRA survey : Bayesian photometric redshifts with 23 bands for 3 deg2
    (2014) Molino, A.; Benítez, N.; Moles, M.; Fernández Soto, A.; Cristóbal-Hornillos, D.; Ascaso, B.; Schoenell, W.; Arnalte-Mur, P.; Jiménez Teja, Y.; Infante Lira, Leopoldo
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    TOROS optical follow-up of the advanced LIGO–VIRGO O2 second observational campaign
    (2020) Artola, R.; Beroiz, M.; Cabral, J.; Camuccio, R.; Castillo, M.; Chavushyan, V.; Colazo, C.; Cuevas, H.; DePoy, D. L.; Díaz, M. C.; Domínguez, M.; Dultzin, D.; Fernández, D.; Ferreyra, A. C.; Fonrouge, A.; Franco, J.; Graña, D.; Girardini, C.; Gurovich, S.; Kanaan, A.; Lambas, D. G.; Lares, M.; Hinojosa, A. F.; Hinojosa, A.; Hinojosa, A. F.; López-Cruz, O.; Macri, L. M.; Marshall, J. L.; Melia, R.; Mendoza, W.; Castelló, J. L. N.; Padilla, N.; Perez, V.; Peñuela, T.; Rattray, W.; Renzi, V.; Ríos-López, E.; Rivera, A. R.; Ribeiro, T.; Rodriguez, H.; Sánchez, B.; Schneiter, M.; Schoenell, W.; Starck, M.; Vrech, R.; Quiñones, C.; Tapia, L.; Tornatore, M.; Torres-Flores, S.; Vilchis, E.; Zadrożn, A.
    We present the methods and results of the optical follow-up, conducted by the Transient Optical Robotic Observatory of the South Collaboration, of gravitational wave events detected during the Advanced LIGO–Virgo second observing run (2016 November–2017 August). Given the limited field of view (∼100 arcmin) of our observational instrumentation, we targeted galaxies within the area of high localization probability that were observable from our sites. We analysed the observations using difference imaging, followed by a random forest algorithm to discriminate between real and spurious transients. Our observations were conducted using telescopes at Estación Astrofísica de Bosque Alegre, Cerro Tololo Inter-American Observatory, the Dr. Cristina V. Torres Memorial Astronomical Observatory, and an observing station in Salta, Argentina.