CHEMICAL CARTOGRAPHY WITH APOGEE: METALLICITY DISTRIBUTION FUNCTIONS AND THE CHEMICAL STRUCTURE OF THE MILKY WAY DISK

By M. Hayden, Jo Bovy, J. Holtzman, D. Nidever, J. Bird, D. Weinberg, B. Andrews, S. Majewski, C. Allende Prieto, Friedrich Anders and 26 more. 2015

338 citations recorded by the source corpus.

Using a sample of 69,919 red giants from the SDSS-III/APOGEE Data Release 12, we measure the distribution of stars in the [α/Fe] versus [Fe/H] plane and the metallicity distribution functions (MDFs) across an unprecedented volume of the Milky Way disk, with radius 3 < R < 15 kpc and height ∣ z ∣ < 2 ?> kpc. Stars in the inner disk (R < 5 kpc) lie along a single track in [α/Fe] versus [Fe/H], starting with α-enhanced, metal-poor stars and ending at [α/Fe] ∼ 0 and [Fe/H] ∼ +0.4. At larger radii we find two distinct sequences in [α/Fe] versus [Fe/H] space, with a roughly solar-α sequence that spans a decade in metallicity and a high-α sequence that merges with the low-α sequence at super-solar [Fe/H]. The location of the high-α sequence is nearly constant across the disk; however, there are very few high-α stars at R > 11 kpc. The peak of the midplane MDF shifts to lower metallicity at larger R, reflecting the Galactic metallicity gradient. Most strikingly, the shape of the midplane MDF changes systematically with radius, from a negatively skewed distribution at 3 < R < 7 kpc, to a roughly Gaussian distribution at the solar annulus, to a positively skewed shape in the outer Galaxy. For stars with ∣ z ∣ > 1 ?> kpc or [α/Fe] > 0.18, the MDF shows little dependence on R. The positive skewness of the outer-disk MDF may be a signature of radial migration; we show that blurring of stellar populations by orbital eccentricities is not enough to explain the reversal of MDF shape, but a simple model of radial migration can do so.

Subfields: Astronomy and Astrophysics, Instrumentation

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Citations in the corpus

STELLAR AND PLANETARY PROPERTIES OF K2 CAMPAIGN 1 CANDIDATES AND VALIDATION OF 17 PLANETS, INCLUDING A PLANET RECEIVING EARTH-LIKE INSOLATION (2015, methodology): “We include a prior on stellar metallicity representative of the observed metallicities of stars within 1 kpc of the Sun, following the results of Hayden et al. (2015), and a Salpeter-slope prior on mass up to the maximum mass available in the model grids of M3.”
Measuring Radial Orbit Migration in the Galactic Disk (2018, methodology): “These distribution functions are well reproduced in most of the disk, showing the expected positive skewness appearing due to radial orbit migration(Hayden et al. 2015; Loebman et al. 2016; Toyouchi & Chiba 2018).”
Impacts of a flaring star-forming disc and stellar radial mixing on the vertical metallicity gradient (2016, background): “4 of Hayden et al. 2015).”
Red Clump Stars from LAMOST II: the outer disc of the Milky Way (2017, background): “It is also noted that, according to Hayden et al. (2015), the outer disc is dominated by low-α stars.”
The Galaxy in Context: Structural, Kinematic, and Integrated Properties (2016, background): “But the more extensive APOGEE survey of 70,000 red giants reveals that the picture is more complicated (Bovy et al. 2015, Hayden et al. 2015).”
A RADIAL AGE GRADIENT IN THE GEOMETRICALLY THICK DISK OF THE MILKY WAY (2016, methodology): “Indeed, the α-rich thick disk is centrally concentrated with a short scale length of about 2 kpc (Bensby et al. 2011; Bovy et al. 2012, 2016; Cheng et al. 2012b), and very few α-rich stars are found in the outer disk of the Milky Way (Nidever et al. 2014; Hayden et al. 2015).”
The influence of Sagittarius and the Large Magellanic Cloud on the stellar disc of the Milky Way Galaxy (2017, background): “If this is true, then Sgr must have been an important agent in shaping the chemical structure of the disc (Hayden et al. 2015) and gradually flaring the different thin-disc stars (Minchev et al. 2015).”
The vertical metallicity gradients of mono-age stellar populations in the Milky Way with the RAVE and Gaia data (2017, methodology): “An indirect approach to determine the vertical metallic- ity of mono-age stellar populations relies on using [α/Fe] as a proxy for age (e.g. Smecker-Hane & Wyse 1992; Haywood et al. 2013; Hayden et al. 2015).”
The GALAH survey: observational overview and Gaia DR1 companion (2016, background): “In particular, spectroscopic stellar surveys are revolutionising our understanding of Galactic structure and evolution (e.g., Helmi 2008; Rix & Bovy 2013; Hayden et al. 2014; Hayden et al. 2015; Martig et al. 2016).”
THE STELLAR POPULATION STRUCTURE OF THE GALACTIC DISK (2015, background): “This distribution contains the two main sequences—high- and low-[α/Fe]–seen in other investigations of this distribution and discussed in detail for the APOGEE sample by Nidever et al. (2014) and Hayden et al. (2015).”
Constraints on Radial Migration in Spiral Galaxies - II. Angular momentum distribution and preferential migration (2018, background): “…gravitational perturbations (for observational evidence, see e.g. Wielen, Fuchs & Dettbarn 1996; Bovy et al. 2012; Radburn-Smith et al. 2012; Hayden et al. 2015; Kordopatis et al. 2015; Loebman et al. 2016 and for theoretical investigations see e.g. Sellwood & Binney 2002; Roškar et al.…”
Metallicity distributions of mono-age stellar populations of the Galactic disc from the LAMOST Galactic spectroscopic surveys (2018, methodology): “The results show that the profile of the [Fe/H] distribution varies with both R and Z. Hayden et al. (2015) demonstrate that the low-[α/Fe] populations close to the Galactic plane have negatively skewed [Fe/H] distributions in the inner disc and positively skewed distributions in the outer disc, a…”
FALSE POSITIVE PROBABILITIES FOR ALL KEPLER OBJECTS OF INTEREST: 1284 NEWLY VALIDATED PLANETS AND 428 LIKELY FALSE POSITIVES (2016, methodology): “Priors used in these fits are listed in Table 1—notably, we use a prior on [Fe/H] based on a double-Gaussian fit to the local metallicity distribution (Hayden et al. 2015; Casagrande et al. 2011).”