Stellar Migration and Chemical Enrichment in the Milky Way Disc: A Hybrid Model

Johnson, James W.; Weinberg, David H.; Vincenzo, Fiorenzo; Bird, Jonathan C.; Loebman, Sarah R.; Brooks, Alyson M.; Quinn, Thomas R.; Christensen, Charlotte R.; Griffith, Emily J.

doi:10.48550/arxiv.2103.09838

Cited by 7 publications

(20 citation statements)

References 141 publications

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“…Quantitative modeling, however, is needed to understand and explain the underlying parameters of the environment that give rise to the systematic changes in individual abundance distributions over time and radius at fixed (Fe, Mg) as seen in the distributions of the residuals of these elements (e.g. Johnson et al 2021;Spitoni et al 2021;Matteucci 2021;Philcox & Rybizki 2019;Rybizki et al 2017, and references therein).…”

Section: Discussionmentioning

confidence: 99%

The homogeneity of the star forming environment of the Milky Way disk over time

Ness,

Wheeler,

McKinnon

et al. 2021

Preprint

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Stellar abundances and ages afford the means to link chemical enrichment to galactic formation. In the Milky Way, individual element abundances show tight correlations with age, which vary in slope across ([Fe/H]-[α/Fe]). Here, we step from characterising abundances as measures of age, to understanding how abundances trace properties of stellar birth-environment in the disk over time. Using measurements from ∼27,000 APOGEE stars (R=22,500, SNR>200), we build simple local linear models to predict a sample of elements (X = Si, O, Ca, Ti, Ni, Al, Mn, Cr) using (Fe, Mg) abundances alone, as fiducial tracers of supernovae production channels. Given [Fe/H] and [Mg/H], we predict these elements, [X/H], to about double the uncertainty of their measurements. The intrinsic dispersion, after subtracting measurement errors in quadrature is ≈ 0.015 − 0.04 dex. The residuals of the prediction (measurement − model) for each element demonstrate that each element has an individual link to birth properties at fixed (Fe, Mg). Residuals from primarily massive-star supernovae (i.e. Si, O, Al) partially correlate with guiding radius. Residuals from primarily supernovae Ia (i.e. Mn, Ni) partially correlate with age. A fraction of the intrinsic scatter that persists at fixed (Fe, Mg), however, after accounting for correlations, does not appear to further discriminate between birth properties that can be traced with present-day measurements. Presumably, this is because the residuals are also, in part, a measure of the typical (in)-homogeneity of the disk's stellar birth environments, previously inferred only using open-cluster systems. Our study implies at fixed birth radius and time, there is a median scatter of ≈ 0.01 − 0.015 dex in elements generated in supernovae sources.

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Section: Discussionmentioning

confidence: 99%

The homogeneity of the star forming environment of the Milky Way disk over time

Ness,

Wheeler,

McKinnon

et al. 2021

Preprint

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“…Theoretically, this approach would benefit from a new generation of Galactic chemical evolution models that predict joint distributions of multiple elements from multiple astrophysical sources. Models that combine stellar radial migration with radially dependent gas accretion, star formation, and outflow histories have achieved impressive (but not complete) success in reproducing many aspects of the observed joint distributions of metallicity, [α/Fe], age, R, and |Z| (e.g., Schönrich & Binney 2009;Minchev et al 2013Minchev et al , 2014Minchev et al , 2017Johnson et al 2021). A natural next step is to extend these models to additional elements, using yields that are theoretically motivated but also empirically constrained to reproduce observed median trends.…”

Section: Prospects and Challengesmentioning

confidence: 99%

Chemical Cartography with APOGEE: Mapping Disk Populations with a Two-Process Model and Residual Abundances

Weinberg,

Holtzman,

Johnson

et al. 2021

Preprint

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We apply a novel statistical analysis to measurements of 16 elemental abundances in 34,410 Milky Way disk stars from the final data release (DR17) of APOGEE-2. Building on recent work, we fit median abundance ratio trends [X/Mg] vs. [Mg/H] with a 2-process model, which decomposes abundance patterns into a "prompt" component tracing core collapse supernovae and a "delayed" component tracing Type Ia supernovae. For each sample star, we fit the amplitudes of these two components, then compute the residuals ∆[X/H] from this two-parameter fit. The rms residuals range from ∼ 0.01 − 0.03 dex for the most precisely measured APOGEE abundances to ∼ 0.1 dex for Na, V, and Ce. The correlations of residuals reveal a complex underlying structure, including a correlated element group comprised of Ca, Na, Al, K, Cr, and Ce and a separate group comprised of Ni, V, Mn, and Co. Selecting stars poorly fit by the 2-process model reveals a rich variety of physical outliers and sometimes subtle measurement errors. Residual abundances allow comparison of populations controlled for differences in metallicity and [α/Fe]. Relative to the main disk (R = 3 − 13 kpc), we find nearly identical abundance patterns in the outer disk (R = 15 − 17 kpc), 0.05-0.2 dex depressions of multiple elements in LMC and Gaia Sausage/Enceladus stars, and wild deviations (0.4-1 dex) of multiple elements in ω Cen. Residual abundance analysis opens new opportunities for discovering chemically distinctive stars and stellar populations, for empirically constraining nucleosynthetic yields, and for testing chemical evolution models that include stochasticity in the production and redistribution of elements.

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“…Therefore there is a time delay in the enrichment of oxygen (or magnesium) and iron (Matteucci & Greggio 1986). There is extensive literature in using in particular [O/Fe]-[Fe/H] planes to constrain chemical evolution models, both of the Milky Way (Johnson et al 2021) and other galaxies (Maiolino & Mannucci 2019). The mass of the progenitor galaxy as well as the star formation history can be addressed from the relation between [α/Fe] and [Fe/H] for a given stellar population (Tinsley 1979).…”

Section: Elemental Abundances As a Function Of Metallicitymentioning

confidence: 99%

“…It particularly helps to constrain the effects of radial migration. Johnson et al (2021) presents an interesting recent discussion about the effect of the dual AMR. The chemical evolution models discussed by Johnson et al (2021) study the effect on the AMR using different star formation rates.…”

Section: Age Metallicity Relation Radial Migrationmentioning

confidence: 99%

“…Yet, quantifying the importance of migration and the net difference in chemical enrichment rates in the disk have remained an open question. The recent work of Johnson et al (2021) used the observed AMR of Feuillet et al (2019) to constrain not only the amount of migration of the fossil stars, but also the migration of the intermediate-mass stars which will become white dwarfs and then explode as Supernova Type Ia (SNIa). Since the latter are long lived, they are able to explote far from their birthplaces.…”

Section: Introductionmentioning

confidence: 99%

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Two sequences in the age-metallicity relation as seen from [C/N] abundances in APOGEE

Jofre

2021

Preprint

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The age-metallicity relation is fundamental to study the formation and evolution of the disk. Observations have shown that this relation has a large scatter which can not be explained by observational errors only. That scatter is hence attributed to the effects of radial migration in which stars tracing different chemical evolution histories in the disk get mixed. However, the recent study of Nissen et al. ( 2020), using high precision observational data of solar type stars, found two relatively tight age-metallicity relations. One sequence of older and metal-richer stars probably traces the chemical enrichment history of the inner disk while the other sequence of younger and metal-poorer stars the chemical enrichment history of the outer disk. If uncertainties in age measurements increase, these sequences mix explaining the scatter of the one relation observed in other studies. This work follows up on these results, by analysing an independent sample of red clump giants observed by APOGEE. Since ages for red giants are significantly more uncertain, the [C/N] ratios are considered as a proxy for age. This larger dataset is used to investigate these relations at different Galactic radii, finding that these distinct sequences exist only in the solar neighbourhood. The APOGEE dataset is further used to explore different abundance and kinematical planes to shed light on the nature of these populations.

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Stellar Migration and Chemical Enrichment in the Milky Way Disc: A Hybrid Model

Cited by 7 publications

References 141 publications

The homogeneity of the star forming environment of the Milky Way disk over time

The homogeneity of the star forming environment of the Milky Way disk over time

Chemical Cartography with APOGEE: Mapping Disk Populations with a Two-Process Model and Residual Abundances

Two sequences in the age-metallicity relation as seen from [C/N] abundances in APOGEE

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