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1. The Open Cluster Chemical Abundances and Mapping Survey. VI. Galactic Chemical Gradient Analysis from APOGEE DR17

   https://doi.org/10.3847/1538-3881/ac7ce5  

   Myers, Natalie ; Donor, John ; Spoo, Taylor ; Frinchaboy, Peter M. ; Cunha, Katia ; Price-Whelan, Adrian M. ; Majewski, Steven R. ; Beaton, Rachael L. ; Zasowski, Gail ; O’Connell, Julia ; et al ( August 2022 , The Astronomical Journal)

   The goal of the Open Cluster Chemical Abundances and Mapping (OCCAM) survey is to constrain key Galactic dynamic and chemical evolution parameters by the construction and analysis of a large, comprehensive, uniform data set of infrared spectra for stars in hundreds of open clusters. This sixth contribution from the OCCAM survey presents analysis of SDSS/APOGEE Data Release 17 (DR17) results for a sample of stars in 150 open clusters, 94 of which we designate to be “high-quality” based on the appearance of their color–magnitude diagram. We find the APOGEE DR17-derived [Fe/H] values to be in good agreement with those from previous high-resolution spectroscopic open cluster abundance studies. Using a subset of the high-quality sample, the Galactic abundance gradients were measured for 16 chemical elements, including [Fe/H], for both Galactocentric radius (R_GC) and guiding center radius (R_guide). We find an overall Galactic [Fe/H] versusR_GCgradient of −0.073 ± 0.002 dex kpc⁻¹over the range of 6 >R_GC< 11.5 kpc, and a similar gradient is found for [Fe/H] versusR_guide. Significant Galactic abundance gradients are also noted for O, Mg, S, Ca, Mn, Na, Al, K, and Ce. Our large sample additionally allows us to explore the evolution of the gradients in four age bins for the remaining 15 elements.

    

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2. High-velocity Stars in SDSS/APOGEE DR17

   https://doi.org/10.3847/1538-3881/ac90bc  

   Quispe-Huaynasi, F. ; Roig, F. ; McDonald, D. J. ; Loaiza-Tacuri, V. ; Majewski, S. R. ; Wanderley, F. C. ; Cunha, K. ; Pereira, C. B. ; Hasselquist, S. ; Daflon, S. ( October 2022 , The Astronomical Journal)

   Abstract We report 23 stars having Galactocentric velocities larger than 450 km s −1 in the final data release of the APOGEE survey. This sample was generated using space velocities derived by complementing the high-quality radial velocities from the APOGEE project in Sloan Digital Sky Survey’s Data Release 17 (DR17) with distances and proper motions from Gaia early Data Release 3 (eDR3). We analyze the observed kinematics and derived dynamics of these stars, considering different potential models for the Galaxy. We find that three stars could be unbound depending on the adopted potential, but in general all of the stars show typical kinematics of halo stars. The APOGEE DR17 spectroscopic results and Gaia eDR3 photometry are used to assess the stellar parameters and chemical properties of the stars. All of the stars belong to the red giant branch, and, in general, they follow the abundance pattern of typical halo stars. There are a few exceptions that would deserve further analysis through high-resolution spectroscopy. In particular, we identify a high-velocity Carbon-Enhanced Metal-Poor star, with a Galactocentric velocity of 482 km s −1 . We do not confirm any hypervelocity star in the sample, but this result is very sensitive to the adopted distances and less sensitive to the Galactic potential. 

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3. On the Hunt for the Origins of the Orphan–Chenab Stream: Detailed Element Abundances with APOGEE and Gaia

   https://doi.org/10.3847/1538-4357/acb698  

   Hawkins, Keith ; Price-Whelan, Adrian M. ; Sheffield, Allyson A. ; Subrahimovic, Aidan Z. ; Beaton, Rachael L. ; Belokurov, Vasily ; Erkal, Denis ; Koposov, Sergey E. ; Lane, Richard R. ; Laporte, Chervin F. P. ; et al ( May 2023 , The Astrophysical Journal)

   Stellar streams in the Galactic halo are useful probes of the assembly of galaxies like the Milky Way. Many tidal stellar streams that have been found in recent years are accompanied by a known progenitor globular cluster or dwarf galaxy. However, the Orphan–Chenab (OC) stream is one case where a relatively narrow stream of stars has been found without a known progenitor. In an effort to find the parent of the OC stream, we use astrometry from the early third data release of ESA’s Gaia mission (Gaia EDR3) and radial velocity information from the Sloan Digital Sky Survey (SDSS)-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey to find up to 13 stars that are likely members of the OC stream. We use the APOGEE survey to study the chemical nature (for up to 10 stars) of the OC stream in theα(O, Mg, Ca, Si, Ti, and S), odd-Z(Al, K, and V), Fe-peak (Fe, Ni, Mn, Co, and Cr), and neutron-capture (Ce) elemental groups. We find that the stars that make up the OC stream are not consistent with a monometallic population and have a median metallicity of −1.92 dex with a dispersion of 0.28 dex. Our results also indicate that the α elements are depleted compared to the known Milky Way populations and that its [Mg/Al] abundance ratio is not consistent with second-generation stars from globular clusters. The detailed chemical pattern of these stars, namely the [α/Fe]–[Fe/H] plane and the metallicity distribution, indicates that the OC stream progenitor is very likely to be a dwarf spheroidal galaxy with a mass of ∼10⁶M_⊙.

    

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4. The Open Cluster Chemical Abundances and Mapping Survey. VII. APOGEE DR17 [C/N]–Age Calibration

   https://doi.org/10.3847/1538-3881/ac5d53  

   Spoo, Taylor ; Tayar, Jamie ; Frinchaboy, Peter M. ; Cunha, Katia ; Myers, Natalie ; Donor, John ; Majewski, Steven R. ; Bizyaev, Dmitry ; García-Hernández, D. A. ; Jönsson, Henrik ; et al ( April 2022 , The Astronomical Journal)

   Large-scale surveys open the possibility to investigate Galactic evolution both chemically and kinematically; however, reliable stellar ages remain a major challenge. Detailed chemical information provided by high-resolution spectroscopic surveys of the stars in clusters can be used as a means to calibrate recently developed chemical tools for age-dating field stars. Using data from the Open Cluster Abundances and Mapping survey, based on the Sloan Digital Sky Survey/Apache Point Observatory Galactic Evolution Experiment 2 survey, we derive a new empirical relationship between open cluster stellar ages and the carbon-to-nitrogen ([C/N]) abundance ratios for evolved stars, primarily those on the red giant branch. With this calibration, [C/N] can be used as a chemical clock for evolved field stars to investigate the formation and evolution of different parts of our Galaxy. We explore how mixing effects at different stellar evolutionary phases, like the red clump, affect the derived calibration. We have established the [C/N]–age calibration for APOGEE Data Release 17 (DR17) giant star abundances to be$\log {[\mathrm{Age}(\mathrm{yr})]}_{\mathrm{DR}17}=10.14(\pm 0.08)+2.23(\pm 0.19)[\mathrm{C}/\mathrm{N}]$, usable for$8.62\le \log (\mathrm{Age}[\mathrm{yr}])\le 9.82$, derived from a uniform sample of 49 clusters observed as part of APOGEE DR17 applicable primarily to metal-rich, thin- and thick-disk giant stars. This measured [C/N]–age APOGEE DR17 calibration is also shown to be consistent with asteroseismic ages derived from Kepler photometry.

    

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5. The Seventeenth Data Release of the Sloan Digital Sky Surveys: Complete Release of MaNGA, MaStar, and APOGEE-2 Data

   https://doi.org/10.3847/1538-4365/ac4414  

   Abdurro’uf ; Accetta, Katherine ; Aerts, Conny ; Silva Aguirre, Víctor ; Ahumada, Romina ; Ajgaonkar, Nikhil ; Filiz Ak, N. ; Alam, Shadab ; Allende Prieto, Carlos ; Almeida, Andrés ; et al ( March 2022 , The Astrophysical Journal Supplement Series)

   Abstract This 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. 

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