CHEMICAL TAGGING CAN WORK: IDENTIFICATION of STELLAR PHASE-SPACE STRUCTURES PURELY by CHEMICAL-ABUNDANCE SIMILARITY

David W. Hogg, Andrew R. Casey, Melissa Ness, Hans Walter Rix, Daniel Foreman-Mackey, Sten Hasselquist, Anna Y.Q. Ho, Jon A. Holtzman, Steven R. Majewski, Sarah L. Martell, Szabolcs Mészáros, David L. Nidever, Matthew Shetrone

    Research output: Contribution to journalArticle

    Abstract

    Chemical tagging promises to use detailed abundance measurements to identify spatially separated stars that were, in fact, born together (in the same molecular cloud) long ago. This idea has not yielded much practical success, presumably because of the noise and incompleteness in chemical-abundance measurements. We have succeeded in substantially improving spectroscopic measurements with The Cannon, which has now delivered 15 individual abundances for stars observed as part of the APOGEE spectroscopic survey, with precisions around 0.04 dex. We test the chemical-tagging hypothesis by looking at clusters in abundance space and confirming that they are clustered in phase space. We identify (by the k-means algorithm) overdensities of stars in the 15-dimensional chemical-abundance space delivered by The Cannon, and plot the associated stars in phase space. We use only abundance-space information (no positional information) to identify stellar groups. We find that clusters in abundance space are indeed clusters in phase space, and we recover some known phase-space clusters and find other interesting structures. This is the first-ever project to identify phase-space structures at the survey-scale by blind search purely in abundance space; it verifies the precision of the abundance measurements delivered by The Cannon; the prospects for future data sets appear very good.

    Original languageEnglish (US)
    Article number262
    JournalAstrophysical Journal
    Volume833
    Issue number2
    DOIs
    StatePublished - Dec 20 2016

    Keywords

    • Galaxy: abundances
    • Galaxy: stellar content
    • Galaxy: structure
    • globular clusters: general
    • open clusters and associations: general
    • stars: abundances

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

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    Hogg, D. W., Casey, A. R., Ness, M., Rix, H. W., Foreman-Mackey, D., Hasselquist, S., Ho, A. Y. Q., Holtzman, J. A., Majewski, S. R., Martell, S. L., Mészáros, S., Nidever, D. L., & Shetrone, M. (2016). CHEMICAL TAGGING CAN WORK: IDENTIFICATION of STELLAR PHASE-SPACE STRUCTURES PURELY by CHEMICAL-ABUNDANCE SIMILARITY. Astrophysical Journal, 833(2), [262]. https://doi.org/10.3847/1538-4357/833/2/262