Browsing by Author "Cunha, Katia"

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    Exploring the Stellar Age Distribution of the Milky Way Bulge Using APOGEE
    (2020) Hasselquist, Sten; Zasowski, Gail; Feuillet, Diane K.; Schultheis, Mathias; Nataf, David M.; Anguiano, Borja; Beaton, Rachael L.; Beers, Timothy C.; Cohen, Roger E.; Cunha, Katia; Fernandez-Trincado, Jose G.; Garcia-Hernandez, D. A.; Geisler, Doug; Holtzman, Jon A.; Johnson, Jennifer; Lane, Richard R.; Majewski, Steven R.; Bidin, Christian Moni; Nitschelm, Christian; Roman-Lopes, Alexandre; Schiavon, Ricardo; Smith, Verne V.; Sobeck, Jennifer
    We present stellar age distributions of the Milky Way bulge region using ages for similar to 6000 high-luminosity (log (g), metal-rich ([Fe/H] >= -0.5) bulge stars observed by the Apache Point Observatory Galactic Evolution Experiment. Ages are derived using The Cannon label-transfer method, trained on a sample of nearby luminous giants with precise parallaxes for which we obtain ages using a Bayesian isochrone-matching technique. We find that the metal-rich bulge is predominantly composed of old stars (>8 Gyr). We find evidence that the planar region of the bulge (vertical bar Z(GC)vertical bar <= 0.25 kpc) is enriched in metallicity, Z, at a faster rate (dZ/dt similar to 0.0034 Gyr(-1)) than regions farther from the plane (dZ/dt similar to 0.0013 Gyr(-1) at vertical bar Z(GC)vertical bar > 1.00 kpc). We identify a nonnegligible fraction of younger stars (age similar to 2-5 Gyr) at metallicities of +0.2 < [Fe/H] < +0.4. These stars are preferentially found in the plane (vertical bar Z(GC)vertical bar <= 0.25 kpc) and at R-cy approximate to 2-3 kpc, with kinematics that are more consistent with rotation than are the kinematics of older stars at the same metallicities. We do not measure a significant age difference between stars found inside and outside the bar. These findings show that the bulge experienced an initial starburst that was more intense close to the plane than far from the plane. Then, star formation continued at supersolar metallicities in a thin disk at 2 kpc less than or similar to R-cy less than or similar to 3 kpc until similar to 2 Gyr ago.
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    Final Targeting Strategy for the Sloan Digital Sky Survey IV Apache Point Observatory Galactic Evolution Experiment 2 North Survey
    (2021) Beaton, Rachael L.; Oelkers, Ryan J.; Hayes, Christian R.; Covey, Kevin R.; Chojnowski, S. D.; De Lee, Nathan; Sobeck, Jennifer S.; Majewski, Steven R.; Cohen, Roger E.; Fernandez-Trincado, Jose; Longa-Pena, Penelope; O'Connell, Julia E.; Santana, Felipe A.; Stringfellow, Guy S.; Zasowski, Gail; Aerts, Conny; Anguiano, Borja; Bender, Chad; Canas, Caleb I.; Cunha, Katia; Donor, John; Fleming, Scott W.; Frinchaboy, Peter M.; Feuillet, Diane; Harding, Paul; Hasselquist, Sten; Holtzman, Jon A.; Johnson, Jennifer A.; Kollmeier, Juna A.; Kounkel, Marina; Mahadevan, Suvrath; Price-Whelan, Adrian. M.; Rojas-Arriagada, Alvaro; Roman-Zuniga, Carlos; Schlafly, Edward F.; Schultheis, Mathias; Shetrone, Matthew; Simon, Joshua D.; Stassun, Keivan G.; Stutz, Amelia M.; Tayar, Jamie; Teske, Johanna; Tkachenko, Andrew; Troup, Nicholas; Albareti, Franco D.; Bizyaev, Dmitry; Bovy, Jo; Burgasser, Adam J.; Comparat, Johan; Downes, Juan Jose; Geisler, Doug; Inno, Laura; Manchado, Arturo; Ness, Melissa K.; Pinsonneault, Marc H.; Prada, Francisco; Roman-Lopes, Alexandre; Simonian, Gregory V. A.; Smith, Verne V.; Yan, Renbin; Zamora, Olga
    The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is a dual-hemisphere, near-infrared (NIR), spectroscopic survey with the goal of producing a chemodynamical mapping of the Milky Way. The targeting for APOGEE-2 is complex and has evolved with time. In this paper, we present the updates and additions to the initial targeting strategy for APOGEE-2N presented in Zasowski et al. (2017). These modifications come in two implementation modes: (i) "Ancillary Science Programs" competitively awarded to Sloan Digital Sky Survey IV PIs through proposal calls in 2015 and 2017 for the pursuit of new scientific avenues outside the main survey, and (ii) an effective 1.5 yr expansion of the survey, known as the Bright Time Extension (BTX), made possible through accrued efficiency gains over the first years of the APOGEE-2N project. For the 23 distinct ancillary programs, we provide descriptions of the scientific aims, target selection, and how to identify these targets within the APOGEE-2 sample. The BTX permitted changes to the main survey strategy, the inclusion of new programs in response to scientific discoveries or to exploit major new data sets not available at the outset of the survey design, and expansions of existing programs to enhance their scientific success and reach. After describing the motivations, implementation, and assessment of these programs, we also leave a summary of lessons learned from nearly a decade of APOGEE-1 and APOGEE-2 survey operations. A companion paper, F. Santana et al. (submitted; AAS29036), provides a complementary presentation of targeting modifications relevant to APOGEE-2 operations in the Southern Hemisphere.
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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 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.