Browsing by Author "Almeida, Andres"

Now showing 1 - 5 of 5
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    Final Targeting Strategy for the SDSS-IV APOGEE-2S Survey
    (2021) Santana, Felipe A.; Beaton, Rachael L.; Covey, Kevin R.; O'Connell, Julia E.; Longa-Pena, Penelope; Cohen, Roger; Fernandez-Trincado, Jose 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, Andres; Anguiano, Borja; Donor, John; Frinchaboy, Peter M.; Hasselquist, Sten; Johnson, Jennifer A.; Kollmeier, Juna A.; Nidever, David L.; Price-Whelan, Adrian M.; Rojas-Arriagada, Alvaro; Schultheis, Mathias; Shetrone, Matthew; Simon, Joshua D.; Aerts, Conny; Borissova, Jura; Drout, Maria R.; Geisler, Doug; Law, C. Y.; Medina, Nicolas; Minniti, Dante; Monachesi, Antonela; Munoz, Ricardo R.; Poleski, Radoslaw; Roman-Lopes, Alexandre; Schlaufman, Kevin C.; Stutz, Amelia M.; Teske, Johanna; Tkachenko, Andrew; Van Saders, Jennifer L.; Weinberger, Alycia J.; Zoccali, Manuela
    APOGEE is a high-resolution (R similar to 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.
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    Sloan digital sky survey IV: Mapping the Milky Way, nearby galaxies, and the distant universe
    (2017) Blanton, Michael R.; Bershady, Matthew A.; Abolfathi, Bela; Albareti, Franco D.; Allende Prieto, Carlos; Almeida, Andres; Alonso García, Javier; Anders, Friedrich; Zoccali, Manuela; Padilla, Nelson; Aquino Ortíz, Eril; Aragón Salamanca, Alfonso; Argudo Fernández, Maria; Armengaud, Eric; Aubourg, Eric; Avila Reese, Vladimir; Lacerna Zambrano, Iván Andrés; Lane, Richard R.; Andrews, Brett; Anderson, Scott F.
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    The Eighteenth Data Release of the Sloan Digital Sky Surveys: Targeting and First Spectra from SDSS-V
    (2023) Almeida, Andres; Anderson, Scott F.; Argudo-Fernandez, Maria; Badenes, Carles; Barger, Kat; Barrera-Ballesteros, Jorge K.; Bender, Chad F.; Benitez, Erika; Besser, Felipe; Bird, Jonathan C.; Bizyaev, Dmitry; Blanton, Michael R.; Bochanski, John; Bovy, Jo; Brandt, William Nielsen; Brownstein, Joel R.; Buchner, Johannes; Bulbul, Esra; Burchett, Joseph N.; Diaz, Mariana Cano; Carlberg, Joleen K.; Casey, Andrew R.; Chandra, Vedant; Cherinka, Brian; Chiappini, Cristina; Coker, Abigail A.; Comparat, Johan; Conroy, Charlie; Contardo, Gabriella; Cortes, Arlin; Covey, Kevin; Crane, Jeffrey D.; Cunha, Katia; Dabbieri, Collin; Davidson, James W.; Davis, Megan C.; de Andrade Queiroz, Anna Barbara; De Lee, Nathan; Mendez Delgado, Jose Eduardo; Demasi, Sebastian; Di Mille, Francesco; Donor, John; Dow, Peter; Dwelly, Tom; Eracleous, Mike; Eriksen, Jamey; Fan, Xiaohui; Farr, Emily; Frederick, Sara; Fries, Logan; Frinchaboy, Peter; Gaensicke, Boris T.; Ge, Junqiang; Gonzalez Avila, Consuelo; Grabowski, Katie; Grier, Catherine; Guiglion, Guillaume; Gupta, Pramod; Hall, Patrick; Hawkins, Keith; Hayes, Christian R.; Hermes, J. J.; Hernandez-Garcia, Lorena; Hogg, David W.; Holtzman, Jon A.; Ibarra-Medel, Hector Javier; Ji, Alexander; Jofre, Paula; Johnson, Jennifer A.; Jones, Amy M.; Kinemuchi, Karen; Kluge, Matthias; Koekemoer, Anton; Kollmeier, Juna A.; Kounkel, Marina; Krishnarao, Dhanesh; Krumpe, Mirko; Lacerna, Ivan; Lago, Paulo Jakson Assuncao; Laporte, Chervin; Liu, Chao; Liu, Ang; Liu, Xin; Lopes, Alexandre Roman; Macktoobian, Matin; Majewski, Steven R.; Malanushenko, Viktor; Maoz, Dan; Masseron, Thomas; Masters, Karen L.; Matijevic, Gal; McBride, Aidan; Medan, Ilija; Merloni, Andrea; Morrison, Sean; Myers, Natalie; Meszaros, Szabolcs; Negrete, C. Alenka; Nidever, David L.; Nitschelm, Christian; Oravetz, Daniel; Oravetz, Audrey; Pan, Kaike; Peng, Yingjie; Pinsonneault, Marc H.; Pogge, Rick; Qiu, Dan; Ramirez, Solange V.; Rix, Hans-Walter; Rosso, Daniela Fernandez; Runnoe, Jessie; Salvato, Mara; Sanchez, Sebastian F.; Santana, Felipe A.; Saydjari, Andrew; Sayres, Conor; Schlaufman, Kevin C.; Schneider, Donald P.; Schwope, Axel; Serna, Javier; Shen, Yue; Sobeck, Jennifer; Song, Ying-Yi; Souto, Diogo; Spoo, Taylor; Stassun, Keivan G.; Steinmetz, Matthias; Straumit, Ilya; Stringfellow, Guy; Sanchez-Gallego, Jose; Taghizadeh-Popp, Manuchehr; Tayar, Jamie; Thakar, Ani; Tissera, Patricia B.; Tkachenko, Andrew; Toledo, Hector Hernandez; Trakhtenbrot, Benny; Fernandez-Trincado, Jose G.; Troup, Nicholas; Trump, Jonathan R.; Tuttle, Sarah; Ulloa, Natalie; Vazquez-Mata, Jose Antonio; Alfaro, Pablo Vera; Villanova, Sandro; Wachter, Stefanie; Weijmans, Anne-Marie; Wheeler, Adam; Wilson, John; Wojno, Leigh; Wolf, Julien; Xue, Xiang-Xiang; Ybarra, Jason E.; Zari, Eleonora; Zasowski, Gail
    The eighteenth data release (DR18) of the Sloan Digital Sky Survey (SDSS) is the first one for SDSS-V, the fifth generation of the survey. SDSS-V comprises three primary scientific programs or "Mappers": the Milky Way Mapper (MWM), the Black Hole Mapper (BHM), and the Local Volume Mapper. This data release contains extensive targeting information for the two multiobject spectroscopy programs (MWM and BHM), including input catalogs and selection functions for their numerous scientific objectives. We describe the production of the targeting databases and their calibration and scientifically focused components. DR18 also includes & SIM;25,000 new SDSS spectra and supplemental information for X-ray sources identified by eROSITA in its eFEDS field. We present updates to some of the SDSS software pipelines and preview changes anticipated for DR19. We also describe three value-added catalogs (VACs) based on SDSS-IV data that have been published since DR17, and one VAC based on the SDSS-V data in the eFEDS field.
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    The Hercules stream as seen by APOGEE-2 South
    (2018) Hunt, Jason A. S.; Bovy, Jo; Perez-Villegas, Angeles; Holtzman, Jon A.; Sobeck, Jennifer; Chojnowski, Drew; Santana, Felipe A.; Palicio, Pedro A.; Wegg, Christopher; Gerhard, Ortwin; Almeida, Andres; Bizyaev, Dmitry; Fernandez-Trincado, Jose G.; Lane, Richard R.; Pelope Longa-Pena, Pen; Majewski, Steven R.; Pan, Kaike; Roman-Lopes, Alexandre
    The Hercules stream is a group of comoving stars in the solar neighbourhood, which can potentially be explained as a signature of either the outer Lindblad resonance (OLR) of a fast Galactic bar or the corotation resonance (CR) of a slower bar. In either case, the feature should be present over a large area of the disc. With the recent commissioning of the APOGEE-2 Southern spectrograph we can search for the Hercules stream at (l, b)=(270 degrees, 0), a direction in which the Hercules stream, if caused by the bar's OLR, would be strong enough to be detected using only the line-of-sight velocities. We clearly detect a narrow, Hercules-like feature in the data that can be traced from the solar neighbourhood to a distance of about 4 kpc. The detected feature matches well the line-of-sight velocity distribution from the fast-bar (OLR) model. Confronting the data with a model where the Hercules stream is caused by the CR of a slower bar leads to a poorer match, as the corotation model does not predict clearly separated modes, possibly because the slow-bar model is too hot.
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    The Open Cluster Chemical Abundances and Mapping Survey. IV. Abundances for 128 Open Clusters Using SDSS/APOGEE DR16
    (2020) Donor, John; Frinchaboy, Peter M.; Cunha, Katia; O'Connell, Julia E.; Prieto, Carlos Allende; Almeida, Andres; Anders, Friedrich; Beaton, Rachael; Bizyaev, Dmitry; Brownstein, Joel R.; Carrera, Ricardo; Chiappini, Cristina; Cohen, Roger; Garcia-Hernandez, D. A.; Geisler, Doug; Hasselquist, Sten; Jonsson, Henrik; Lane, Richard R.; Majewski, Steven R.; Minniti, Dante; Bidin, Christian Moni; Pan, Kaike; Roman-Lopes, Alexandre; Sobeck, Jennifer S.; Zasowski, Gail
    The Open Cluster Chemical Abundances and Mapping (OCCAM) survey aims to constrain key Galactic dynamical and chemical evolution parameters by the construction of a large, comprehensive, uniform, infrared-based spectroscopic data set of hundreds of open clusters. This fourth contribution from the OCCAM survey presents analysis using Sloan Digital Sky Survey/APOGEE DR16 of a sample of 128 open clusters, 71 of which we designate to be "high quality" based on the appearance of their color-magnitude diagram. We find the APOGEE DR16 derived [Fe/H] abundances to be in good agreement with previous high-resolution spectroscopic open cluster abundance studies. Using the high-quality sample, we measure Galactic abundance gradients in 16 elements, and find evolution of some of the [X/Fe] gradients as a function of age. We find an overall Galactic [Fe/H] versus R-GC gradient of -0.068 0.001 dex kpc(-1) over the range of 6 R-GC < 13.9 kpc; however, we note that this result is sensitive to the distance catalog used, varying as much as 15%. We formally derive the location of a break in the [Fe/H] abundance gradient as a free parameter in the gradient fit for the first time. We also measure significant Galactic gradients in O, Mg, S, Ca, Mn, Cr, Cu, Na, Al, and K, some of which are measured for the first time. Our large sample allows us to examine four well-populated age bins in order to explore the time evolution of gradients for a large number of elements and comment on possible implications for Galactic chemical evolution and radial migration.