Examinando por Autor "Anguiano, Borja"
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Ítem APOGEE chemical abundance patterns of the massive milky way satellites(IOP Publishing Ltd, 2021-12) Hasselquist, Sten; Hayes, Christian R; Lian, Jianhui; Weinberg, David H.; Zasowski, Gail; Horta, Danny; Beaton, Rachael; Feuillet, Diane K.; Garro, Elisa R.; Gallart, Carme; Smith, Verne V.; Holtzman, Jon A.; Minniti, Dante; Lacerna, Ivan; Shetrone, Matthew; Jönsson, Henrik; Cioni, Maria-Rosa L.; Fillingham, Sean P.; Cunha, Katia; O'Connell, Robert; Fernández-Trincado, José G.; Munoz, Ricardo R.; Schiavon, Ricardo; Almeida, Andres; Anguiano, Borja; Beers, Timothy C.; Bizyaev, Dmitry; Brownstein, Joel R.; Cohen, Roger E.; Frinchaboy, Peter; García-Hernández, D.A.; Geisler, Doug; Lane, Richard R.; Majewski, Steven R; Nidever, David L.; Nitschelm, Christian; Povick, Joshua; Price-Whelan, Adrian; Roman-Lopes, Alexandre; Rosado, Margarita; Sobeck, Jennifer; Stringfellow, Guy; Valenzuela, Octavio; Villanova, Sandro; Vincenzo, FiorenzoThe SDSS-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey has obtained high resolution spectra for thousands of red giant stars distributed among the massive satellite galaxies of the Milky Way (MW): the Large and Small Magellanic Clouds (LMC/SMC), the Sagittarius Dwarf Galaxy (Sgr), Fornax (Fnx), and the now fully disrupted Gaia Sausage/Enceladus (GSE) system. We present and analyze the APOGEE chemical abundance patterns of each galaxy to draw robust conclusions about their star formation histories, by quantifying the relative abundance trends of multiple elements (C, N, O, Mg, Al, Si, Ca, Fe, Ni, and Ce), as well as by fitting chemical evolution models to the [α/Fe]–[Fe/H] abundance plane for each galaxy. Results show that the chemical signatures of the starburst in the Magellanic Clouds (MCs) observed by Nidever et al. in the α-element abundances extend to C+N, Al, and Ni, with the major burst in the SMC occurring some 3–4 Gyr before the burst in the LMC. We find that Sgr and Fnx also exhibit chemical abundance patterns suggestive of secondary star formation epochs, but these events were weaker and earlier (∼5–7 Gyr ago) than those observed in the MCs. There is no chemical evidence of a second starburst in GSE, but this galaxy shows the strongest initial star formation as compared to the other four galaxies. All dwarf galaxies had greater relative contributions of AGB stars to their enrichment than the MW. Comparing and contrasting these chemical patterns highlight the importance of galaxy environment on its chemical evolution.Ítem APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy(Institute of Physics Publishing, 2017-09) Hasselquist, Sten; Shetrone, Matthew; Smith, Verne; Holtzman, Jon; McWilliam, Andrew; Fernández-Trincado J.G.; Beers, Timothy C.; Majewski, Steven R.; Nidever, David L.; Tang, Baitian; Tissera, Patricia B.; Alvar, Emma Fernández; Allende Prieto, Carlos; Almeida, Andres; Anguiano, Borja; Battaglia, Giuseppina; Carigi, Leticia; Delgado Inglada, Gloria; Frinchaboy, Peter; Garcia-Hernández D.A.; Geisler, Doug; Minniti, Dante; Placco, Vinicius M.; Schultheis, Mathias; Sobeck, Jennifer; Villanova, SandroThe Apache Point Observatory Galactic Evolution Experiment provides the opportunity of measuring elemental abundances for C, N, O, Na, Mg, Al, Si, P, K, Ca, V, Cr, Mn, Fe, Co, and Ni in vast numbers of stars. We analyze thechemical-abundance patterns of these elements for 158 red giant stars belonging to the Sagittarius dwarf galaxy (Sgr). This is the largest sample of Sgr stars with detailed chemical abundances, and it is the first time that C, N, P, K, V, Cr, Co, and Ni have been studied at high resolution in this galaxy. We find that the Sgr stars with [Fe/H] ≈ -0.8 are deficient in all elemental abundance ratios (expressed as [X/Fe]) relative to the Milky Way, suggesting that the Sgr stars observed today were formed from gas that was less enriched by Type II SNe than stars formed in the Milky Way. By examining the relative deficiencies of the hydrostatic (O, Na, Mg, and Al) and explosive (Si, P, K, and Mn) elements, our analysis supports the argument that previous generations of Sgr stars were formed with a top-light initial mass function, one lacking the most massive stars that would normally pollute the interstellar medium with the hydrostatic elements. We use a simple chemical-evolution model, flexCE, to further support our claim and conclude that recent stellar generations of Fornax and the Large Magellanic Cloud could also have formed according to a top-light initial mass function. © 2017. The American Astronomical Society. All rights reserved..Ítem Final Targeting Strategy for the SDSS-IV APOGEE-2S Survey(American Astronomical Society, 2021-12-01) Santana, Felipe A.; Beaton, Rachael L.; Covey, Kevin R.; O'Connell, Julia E.; Longa-Peña, Penélope; Cohen, Roger; Fernández-Trincado, José G.; Hayes, Christian R.; Zasowski, Gail; Sobeck, Jennifer S.; Majewski, Steven R.; Chojnowski, S. D.; De Lee, Nathan; Oelkers, Ryan J.; Stringfellow, Guy S.; Almeida, Andrés; Anguiano, Borja; Donor, John; Frinchaboy, Peter M.; Hasselquist, Sten; Johnson, Jennifer A.; Kollmeier, Juna A.; Nidever, David L.; Price-Whelan, Adrian M.; Rojas-Arriagada, Álvaro; Schultheis, Mathias; Shetrone, Matthew; Simon, Joshua D.; Aerts, Conny; Borissova, Jura; Drout, María R.; Geisler, Doug; Law, C. Y.; Medina, Nicolas; Minniti, Dante; Monachesi, Antonela; Muñoz, Ricardo R.; Poleski, Radosław; Roman-Lopes, Alexandre; Schlaufman, Kevin C.; Stutz, Amelia M.; Teske, Johanna; Tkachenko, Andrew; Van Saders, Jennifer L.; Weinberger, Alycia J.; Zoccali, ManuelaAPOGEE is a high-resolution (R ∼ 22,000), near-infrared, multi-epoch, spectroscopic survey of the Milky Way. The second generation of the APOGEE project, APOGEE-2, includes an expansion of the survey to the Southern Hemisphere called APOGEE-2S. This expansion enabled APOGEE to perform a fully panoramic mapping of all of the main regions of the Milky Way; in particular, by operating in the H band, APOGEE is uniquely able to probe the dust-hidden inner regions of the Milky Way that are best accessed from the Southern Hemisphere. In this paper we present the targeting strategy of APOGEE-2S, with special attention to documenting modifications to the original, previously published plan. The motivation for these changes is explained as well as an assessment of their effectiveness in achieving their intended scientific objective. In anticipation of this being the last paper detailing APOGEE targeting, we present an accounting of all such information complete through the end of the APOGEE-2S project; this includes several main survey programs dedicated to exploration of major stellar populations and regions of the Milky Way, as well as a full list of programs contributing to the APOGEE database through allocations of observing time by the Chilean National Time Allocation Committee and the Carnegie Institution for Science. This work was presented along with a companion article, Beaton et al. (2021), presenting the final target selection strategy adopted for APOGEE-2 in the Northern Hemisphere.Ítem The chemical characterization of halo substructure in the Milky Way based on APOGEE(Oxford University Press, 2023-04) Horta, Danny; Schiavon, Ricardo P.; Mackereth, J. Ted; Weinberg, David H.; Hasselquist, Sten; Feuillet, Diane; O’Connell, Robert W.; Anguiano, Borja; Allende-Prieto, Carlos; Beaton, Rachael L.; Bizyaev, Dmitry; Cunha, Katia; Geisler, Doug; García-Hernández D.A.; Holtzman, Jon; Jönsson, Henrik; Lane, Richard R.; Majewski, Steve R.; Mészáros, Szabolcs; Minniti, Dante; Nitschelm, Christian; Shetrone, Matthew; Smith, Verne V.; Zasowski, GailGalactic haloes in a Λ-CDM universe are predicted to host today a swarm of debris resulting from cannibalized dwarf galaxies. The chemodynamical information recorded in their stellar populations helps elucidate their nature, constraining the assembly history of the Galaxy. Using data from APOGEE and Gaia, we examine the chemical properties of various halo substructures, considering elements that sample various nucleosynthetic pathways. The systems studied are Heracles, Gaia-Enceladus/Sausage (GES), the Helmi stream, Sequoia, Thamnos, Aleph, LMS-1, Arjuna, I’itoi, Nyx, Icarus, and Pontus. Abundance patterns of all substructures are cross-compared in a statistically robust fashion. Our main findings include: (i) the chemical properties of most substructures studied match qualitatively those of dwarf Milky Way satellites, such as the Sagittarius dSph. Exceptions are Nyx and Aleph, which are chemically similar to disc stars, implying that these substructures were likely formed in situ; (ii) Heracles differs chemically from in situ populations such as Aurora and its inner halo counterparts in a statistically significant way. The differences suggest that the star formation rate was lower in Heracles than in the early Milky Way; (iii) the chemistry of Arjuna, LMS-1, and I’itoi is indistinguishable from that of GES, suggesting a possible common origin; (iv) all three Sequoia samples studied are qualitatively similar. However, only two of those samples present chemistry that is consistent with GES in a statistically significant fashion; (v) the abundance patterns of the Helmi stream and Thamnos are different from all other halo substructures. © 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.Ítem The origin of accreted stellar halo populations in the milky way using apogee, gaia, and the eagle simulations(Monthly Notices of the Royal Astronomical Society, 2019-01-21) Mackereth, J. Ted; Schiavon, Ricardo P.; Pfeffer, Joel; Hayes, Christian R.; Bovy, Jo; Anguiano, Borja; Prieto, Carlos Allende; Hasselquist, Sten; Holtzman, Jon; Johnson, Jennifer A.; Majewski, Steven R.; O’Connell, Robert; Shetrone, Matthew; Tissera, Patricia B.; Fernandez-Trincado, J. G.Kinematics of halo stars. We show that ∼2/3 of nearby halo stars have high orbital eccentricities (e 0.8), and abundance patterns typical of massive Milky Way dwarf galaxy satellites today, characterized by relatively low [Fe/H], [Mg/Fe], [Al/Fe], and [Ni/Fe]. The trend followed by high-e stars in the [Mg/Fe]-[Fe/H] plane shows a change of slope at [Fe/H] ∼ -1.3, which is also typical of stellar populations from relatively massive dwarf galaxies. Low-e stars exhibit no such change of slope within the observed [Fe/H] range and show slightly higher abundances of Mg, Al, and Ni. Unlike their low-e counterparts, high-e stars show slightly retrograde motion, make higher vertical excursions, and reach larger apocentre radii. By comparing the position in [Mg/Fe]-[Fe/H] space of high-e stars with those of accreted galaxies from the EAGLE suite of cosmological simulations, we constrain the mass of the accreted satellite to be in the range 108.5≲ M ≲ 109M⊙ We show that the median orbital eccentricities of debris are largely unchanged since merger time, implying that this accretion event likely happened at z≲1.5. The exact nature of the low-e population is unclear, but we hypothesize that it is a combination of in situ star formation, high-|z| disc stars, lower mass accretion events, and contamination by the low-e tail of the high-e population. Finally, our results imply that the accretion history of the Milky Way was quite unusual.Ítem The Seventeenth Data Release of the Sloan Digital Sky Surveys: Complete Release of MaNGA, MaStar, and APOGEE-2 Data(American Astronomical Society, 2022-04-01) Abdurro'Uf; Accetta, Katherine; Aerts, Conny; Silva Aguirre, Víctor; Ahumada, Romina; Ajgaonkar, Nikhil; Filiz Ak, N.; Alam, Shadab; Allende Prieto, Carlos; Almeida, Andrés; Anders, Friedrich; Anderson, Scott F.; Andrews, Brett H.; Anguiano, Borja; Aquino-Ortíz, Erik; Aragón-Salamanca, Alfonso; Argudo-Fernández, Maria; Ata, Metin; Aubert, Marie; Avila-Reese, Vladimir; Badenes, Carles; Barbá, Rodolfo H.; Barger, Kat; Barrera-Ballesteros, Jorge K.; Beaton, Rachael L.; Beers, Timothy C.; Belfiore, Francesco; Bender, Chad F.; Bernardi, Mariangela; Bershady, Matthew A.; Beutler, Florian; Bidin, Christian Moni; Bird, Jonathan C.; Bizyaev, Dmitry; Blanc, Guillermo A.; Blanton, Michael R.; Boardman, Nicholas Fraser; Bolton, Adam S.; Boquien, Médéric; Borissova, Jura; Bovy, Jo; Brandt, W.N.; Brown, Jordan; Brownstein, Joel R.; Brusa, Marcella; Buchner, Johannes; Bundy, Kevin; Burchett, Joseph N.; Bureau, Martin; Burgasser, Adam; Cabang, Tuesday K.; Campbell, Stephanie; Cappellari, Michele; Carlberg, Joleen K.; Wanderley, Fábio Carneiro; Carrera, Ricardo; Cash, Jennifer; Chen, Yan-Ping; Chen, Wei-Huai; Cherinka, BrianThis paper documents the seventeenth data release (DR17) from the Sloan Digital Sky Surveys; the fifth and final release from the fourth phase (SDSS-IV). DR17 contains the complete release of the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, which reached its goal of surveying over 10,000 nearby galaxies. The complete release of the MaNGA Stellar Library accompanies this data, providing observations of almost 30,000 stars through the MaNGA instrument during bright time. DR17 also contains the complete release of the Apache Point Observatory Galactic Evolution Experiment 2 survey that publicly releases infrared spectra of over 650,000 stars. The main sample from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), as well as the subsurvey Time Domain Spectroscopic Survey data were fully released in DR16. New single-fiber optical spectroscopy released in DR17 is from the SPectroscipic IDentification of ERosita Survey subsurvey and the eBOSS-RM program. Along with the primary data sets, DR17 includes 25 new or updated value-added catalogs. This paper concludes the release of SDSS-IV survey data. SDSS continues into its fifth phase with observations already underway for the Milky Way Mapper, Local Volume Mapper, and Black Hole Mapper surveys. © 2022. The Author(s). Published by the American Astronomical Society.