Abundances, Stellar Parameters, and Spectra From the SDSS-Iii/Apogee Survey

Holtzman, Jon A.; Shetrone, Matthew; Johnson, Jennifer A.; Prieto, C. Allende; Anders, F.; Andrews, Brett H.; Beers, Timothy C.; Bizyaev, Dmitry; Blanton, Michael R.; Bovy, Jo; Carrera, R.; Chojnowski, S. Drew; Cunha, Kátia; Eisenstein, Daniel J.; Feuillet, Diane; Frinchaboy, Peter M.; Galbraith-Frew, Jessica; Pérez, Ana E. García; García-Hernández, D. A.; Hasselquist, Sten; Hayden, Michael R.; Hearty, Fred; Ivans, Inese I.; Majewski, Steven R.; Martell, Sarah L.; Mészáros, Szabolcs; Muna, Demitri; Nidever, David L.; Nguyen, Duy Cuong; O’Connell, R. W.; Pan, Kaike; Pinsonneault, Marc H.; Robin, A. C.; Schiavon, Ricardo P.; Shane, N.; Sobeck, Jennifer; Smith, Verne V.; Troup, Nicholas; Weinberg, David H.; Wilson, John C.; Wood‐Vasey, W. M.; Zamora, Olga; Zasowski, Gail

doi:10.1088/0004-6256/150/5/148

Cited by 384 publications

(384 citation statements)

References 37 publications

(48 reference statements)

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“…Using the same 2.5m telescope at Apache Point Observatory as that employed for previous SDSS projects (Gunn et al 2006), APOGEE is a Galactic survey designed to obtain infrared stellar spectra in the H-band (1.5-1.7 µm) with a resolving power of R ∼ 22, 500. From such spectra, stellar atmospheric parameters and chemical abundances of 15 elements (C, N, O, Na, Mg, Al, Si, S, K, Ca, Ti, V, Mn, Fe, Ni) were determined with the ASPCAP pipeline (García Pérez et al 2016;Holtzman et al 2015). APOGEE was designed to explore the principal stellar components of the Galaxy, mainly the Galactic disk and bulge, but it also observed stars that are members of the Galactic halo.…”

Section: Observationsmentioning

confidence: 99%

“…In addition, we do not consider the spectra of stars with the GRIDEDGE_BAD flag set in the ELEMFLAG bitmask, which correspond to those stars for which the resulting abundance estimate is closer than 1/8th of the grid spacing to the edge of grid (see García Pérez et al 2016). Finally, we also avoid stars with spectra affected by persistence in the detectors (which may lead to significant errors in stellar parameters and abundance determination -see Section 5.7 in Holtzman et al 2015), by considering only stars that do not have the PERSIST_LOW, PERSIST_MED and PER-SIST_HIGH flags set in the STARFLAG bitmask. For more details about APOGEE flags we refer the interested reader to the web page http://www.sdss.org/dr12/algorithms/bitmasks/.…”

Section: Samplementioning

confidence: 99%

“…A systematic over-estimate at low metallicities was detected in Holtzman et al 2015 We are interested in evaluating differences in the behaviours of individual elemental abundances. The [M/H] determination is influenced by the contribution of elements other than iron, which can induce deviation from the true iron abundance.…”

Section: Stellar Parameters and Chemical Abundancesmentioning

confidence: 99%

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Chemical trends in the Galactic halo from APOGEE data

Fernández-Alvar

Carigi

Prieto

et al. 2016

Mon. Not. R. Astron. Soc.

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The galaxy formation process in the Λ-Cold Dark Matter scenario can be constrained from the analysis of stars in the Milky Way's halo system. We examine the variation of chemical abundances in distant halo stars observed by the Apache Point Galactic Evolution Experiment (APOGEE), as a function of distance from the Galactic center (r) and iron abundance ([M/H]), in the range 5 r 30 kpc and −2.5 < [M/H] < 0.0. We perform a statistical analysis of the abundance ratios derived by the APOGEE pipeline (ASPCAP) and distances calculated by several approaches. Our analysis reveals signatures of a different chemical enrichment between the inner and outer regions of the halo, with a transition at about 15 kpc. The derived metallicity distribution function exhibits two peaks, at [M/H] ∼ −1.5 and ∼ −2.1, consistent with previously reported halo metallicity distributions. We obtain a difference of ∼ 0.1 dex for α-element-to-iron ratios for stars at r > 15 kpc and [M/H] > −1.1 (larger in the case of O, Mg and S) with respect to the nearest halo stars. This result confirms previous claims for low-α stars found at larger distances. Chemical differences in elements with other nucleosynthetic origins (Ni, K, Na, and Al) are also detected. C and N do not provide reliable information about the interstellar medium from which stars formed because our sample comprises RGB and AGB stars and can experience mixing of material to their surfaces.

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Section: Observationsmentioning

confidence: 99%

Section: Samplementioning

confidence: 99%

Section: Stellar Parameters and Chemical Abundancesmentioning

confidence: 99%

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Chemical trends in the Galactic halo from APOGEE data

Fernández-Alvar

Carigi

Prieto

et al. 2016

Mon. Not. R. Astron. Soc.

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“…The spectra can be downloaded from the Science Archive Server (SAS) as described on the data access page. 3 There are three different types of reduced spectra available (see Holtzman et al 2015;Nidever et al 2015). Here, we use the calibrated, well-sampled, and pseudo continuum-normalized combined 1D spectra.…”

Section: Used Information Extracted From the Apogee Archivementioning

confidence: 99%

“…We also use the table that summarizes all the parameters derived from the APOGEE spectra (for DR12, allStar-v603. fits), including for each observed individual star its mean barycentric radial velocity, the standard deviation of the mean velocity, the mean ASPCAP parameters and abundances as derived from the combined spectra, and a compilation of ancillary targeting data (see Holtzman et al 2015;Nidever et al 2015, for a full description of the data in these files).…”

Section: Used Information Extracted From the Apogee Archivementioning

confidence: 99%

A CATALOG OF 1.5273 μm DIFFUSE INTERSTELLAR BANDS BASED ON APOGEE HOT TELLURIC CALIBRATORS

Elyajouri

Monreal-Ibero

Remy

et al. 2016

ApJS

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High resolution stellar spectroscopic surveys provide massive amounts of diffuse interstellar bands (DIBs) measurements. Data can be used to study the distribution of the DIB carriers and those environmental conditions that favor their formation. In parallel, recent studies have also proved that DIBs extracted from stellar spectra constitute new tools for building the 3D structure of the Galactic interstellar medium (ISM). The amount of details on the structure depends directly on the quantity of available lines of sight. Therefore there is a need to construct databases of high-quality DIB measurements as large as possible. We aim at providing the community with a catalog of high-quality measurements of the 1.5273 μm DIB toward a large fraction of the Apache Point Observatory Galactic Evolution Experiment (APOGEE) hot stars observed to correct for the telluric absorption and not used for ISM studies so far. This catalog would complement the extensive database recently extracted from the APOGEE observations and used for 3D ISM mapping. We devised a method to fit the stellar continuum of the hot calibration stars and extracted the DIB from the normalized spectrum. Severe selection criteria based on the absorption characteristics are applied to the results. In particular limiting constraints on the DIB widths and Doppler shifts are deduced from the H I 21 cm measurements, following a new technique of decomposition of the emission spectra. From ∼16,000 available hot telluric spectra we have extracted ∼6700 DIB measurements and their associated uncertainties. The statistical properties of the extracted absorptions are examined and our selection criteria are shown to provide a robust dataset. The resulting catalog contains the DIB total equivalent widths, central wavelengths and widths. We briefly illustrate its potential use for the stellar and interstellar communities.

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Automated pipelines for spectroscopic analysis

Prieto

2016

Astron Nachr

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The Gaia mission will have a profound impact on our understanding of the structure and dynamics of the Milky Way. Gaia is providing an exhaustive census of stellar parallaxes, proper motions, positions, colors and radial velocities, but also leaves some glaring holes in an otherwise complete data set. The radial velocities measured with the on-board highresolution spectrograph will only reach some 10 % of the full sample of stars with astrometry and photometry from the mission, and detailed chemical information will be obtained for less than 1 %. Teams all over the world are organizing large-scale projects to provide complementary radial velocities and chemistry, since this can now be done very efficiently from the ground thanks to large and mid-size telescopes with a wide field-of-view and multi-object spectrographs. As a result, automated data processing is taking an ever increasing relevance, and the concept is applying to many more areas, from targeting to analysis. In this paper, I provide a quick overview of recent, ongoing, and upcoming spectroscopic surveys, and the strategies adopted in their automated analysis pipelines.

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Abundances, Stellar Parameters, and Spectra From the SDSS-Iii/Apogee Survey

Cited by 384 publications

References 37 publications

Chemical trends in the Galactic halo from APOGEE data

Chemical trends in the Galactic halo from APOGEE data

A CATALOG OF 1.5273 μm DIFFUSE INTERSTELLAR BANDS BASED ON APOGEE HOT TELLURIC CALIBRATORS

Automated pipelines for spectroscopic analysis

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