A. E. García Pérez

Target selection for the Apache Point Observatory Galactic Evolution Experiment (APOGEE)

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) is a high-resolution infrared spectroscopic survey spanning all Galactic environments (i.e., bulge, disk, and halo), with the principal goal of constraining dynamical and chemical evolution models of the Milky Way. APOGEE takes advantage of the reduced effects of extinction at infrared wavelengths to observe the inner Galaxy and bulge at an unprecedented level of detail. The surveys broad spatial and wavelength coverage enables users of APOGEE data to address numerous Galactic structure and stellar populations issues. In this paper we describe the APOGEE targeting scheme and document its various target classes to provide the necessary background and reference information to analyze samples of APOGEE data with awareness of the imposed selection criteria and resulting sample properties. APOGEEs primary sample consists of ~105 red giant stars, selected to minimize observational biases in age and metallicity. We present the methodology and considerations that drive the selection of this sample and evaluate the accuracy, efficiency, and caveats of the selection and sampling algorithms. We also describe additional target classes that contribute to the APOGEE sample, including numerous ancillary science programs, and we outline the targeting data that will be included in the public data releases.

On OH line formation and oxygen abundances in metal-poor stars

The formation of the UV OH spectral lines has been investigated for a range of stellar parameters in the light of 3D hydrodynamical model atmospheres. The low atmospheric temperatures encountered at low metallicities compared with the radiative equilibrium values enforced in classical 1D hydrostatic model atmo- spheres have a profound impact on the OH line strengths. As a consequence, the derived O abundances using 3D models are found to be systematically lower by more than 0.6 dex at (Fe/H) = 3: 0c ompared with previous 1D analyses, casting doubts on the recent claims for a monotonic increase in (O/Fe) towards lower metallicities. In fact, taken at face value the resulting 3D LTE trend is in rough agreement with the conventional (O/Fe) plateau. Caution must, however, be exercised in view of the remaining assumptions in the 3D calculations. We have veried that the stellar parameters remain essentially unchanged with 3D model atmospheres provided that the infrared flux method (Te < 20 K), Hipparcos parallaxes (logg < 0:05) and Fe ii lines ((Fe=H) < 0: 1d ex) are utilised, leaving the 3D O abundances from OH lines largely intact ((O=H) < 0:05 dex). Greater concern stems from possible departures from LTE in both the line formation and the molecular equilibrium, which, if present, would increase the derived O abundances again. Non-LTE line formation calculations with 1D model atmospheres suggest no signicant steepening of the (O/Fe) trend even if the abundance corrections amount to about 0.2 dex for all investigated stellar parameters. We note, however, that the 3D case may not necessarily be as metallicity-independent. The apparent lack of laboratory or theoretical rate coecients at the relevant tem- peratures for the involved molecular reactions unfortunately prevents a quantitative discussion on the possible eects of non-equilibrium chemistry.

Chemodynamics of the Milky Way - I. The first year of APOGEE data

We investigate the chemo-kinematic properties of the Milky Way disc by exploring the first year of data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE), and compare our results to smaller optical high-resolution samples in the literature, as well as results from lower resolution surveys such as GCS, SEGUE and RAVE. We start by selecting a high-quality sample in terms of chemistry (

Calibrations of Atmospheric Parameters Obtained from the First Year of SDSS-III APOGEE Observations

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Exploring the origin of lithium, carbon, strontium, and barium with four new ultra metal-poor stars

20.000 stars) and, after computing distances and orbital parameters for this sample, we employ a number of useful subsets to formulate constraints on Galactic chemical and chemodynamical evolution processes in the Solar neighbourhood and beyond (e.g., metallicity distributions -- MDFs, [

Oxygen abundances in metal-poor subgiants as determined from [O I], O I and OH lines

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Extinction Maps Toward The Milky Way Bulge: Two-Dimensional And Three-Dimensional Tests With APOGEE

/Fe] vs. [Fe/H] diagrams, and abundance gradients). Our red giant sample spans distances as large as 10 kpc from the Sun. We find remarkable agreement between the recently published local (d

New H-Band Stellar Spectral Libraries For The SDSS-III/APOGEE Survey

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THE SDSS-III APOGEE SPECTRAL LINE LIST FOR H-BAND SPECTROSCOPY

100 pc) high-resolution high-S/N HARPS sample and our local HQ sample (d

Performance of the apache point observatory galactic evolution experiment (APOGEE) high-resolution near-infrared multi-object fiber spectrograph

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