Chemical Abundances in Stars

Start year
2010
Organizational Unit

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    General
    Description

    Stellar spectroscopy allows us to determine the properties and chemical compositions of stars. From this information for stars of different ages in the Milky Way, it is possible to reconstruct the chemical evolution of the Galaxy, as well as the origin of the elements heavier than boron, created mainly in stellar interiors. It is also possible to study stellar formation, and the formation of the Galaxy, from the signature of the Galactic potential on the stellar orbits, and the distributions of mass, ages, and the abundance of heavy elements.

    Obtaining high-resolution spectra, as necessary for studies of chemical compositions, requires advanced and efficient instrumentation. This is particularly true for research that calls for large stellar samples, which demands the observation of hundreds or thousands of sources simultaneously. Efficiency requires that the data processing and analysis are performed in an automated way.

    The interpretation of spectra is based on physical models of the atmospheres of the stars, from where the light that we observe escapes the stars. The main ingredients for building such models are the fluid dynamics, and the properties of the atoms, ions, and molecules, especially regarding their interactions with the radiation coming from the stellar interior.

    Once we have a plausible model, it is possible to compute in detail how the radiation propagates through the stellar atmosphere, and the emergent spectrum, which can then be iteratively compared with the observations to refine the model.

    This project covers three different research fronts:

    - Improving model atmospheres and simulations of stellar spectra.

    - Developing tools for acquisition, reduction, and analysis of spectroscopic observations, in particular for the determination of chemical abundances in stars.

    - Designing, preparing, and executing spectroscopic studies of stars aimed at understanding a) the most relevant aspects of the physics of stellar atmospheres, b) the formation and evolution of stars, c) the origin of the chemical elements, and d) the formation, structure, and evolution of the Milky Way galaxy.

    Principal investigator
    Project staff
    Collaborators
    Dr.
    I. Hubeny
    Dr.
    B. Castanheira
    Dr.
    M. Kilic
    Dr.
    S. Majewski
    Dr.
    H.G. Ludwig
    Dr.
    M. Cropper
    Dr.
    M. P. Ruffoni
    Dr.
    J. C. Pickering
    Dr.
    K. Cunha
    Dr.
    Andrew Cooper
    Dr.
    Boris Gaensicke
    1. Complete the installation and commissioning of HORuS on GTC
    2. Discover two new stars with more than 100,000 times less iron than the Sun
    3. Complete the classification of all the APOGEE spectra with K-means
    4. Publish a complete collection of model stellar spectra for stars O to M
    5. Identify the signature of chemical diffusion in the atmospheres of the stars in the cluster M67

    Related publications

    J0815+4729: A Chemically Primitive Dwarf Star in the Galactic Halo Observed with Gran Telescopio Canarias 2018ApJ...852L..20A
    Metallicity gradient of the thick disc progenitor at high redshift 2018MNRAS.473..867K
    Elemental Abundances of Kepler Objects of Interest in APOGEE. I. Two Distinct Orbital Period Regimes Inferred from Host Star Iron Abundances 2018AJ....155...68W
    12C/13C isotopic ratios in red-giant stars of the open cluster NGC 6791 2018MNRAS.474.4810S
    The Pristine survey - III. Spectroscopic confirmation of an efficient search for extremely metal-poor stars 2017MNRAS.472.2963Y
    The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory 2017ApJS..233...25A
    Gaia Data Release 1. Testing parallaxes with local Cepheids and RR Lyrae stars 2017A&A...605A..79G
    Adding the s-Process Element Cerium to the APOGEE Survey: Identification and Characterization of Ce ii Lines in the H-band Spectral Window 2017ApJ...844..145C
    APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy 2017ApJ...845..162H
    The Apache Point Observatory Galactic Evolution Experiment (APOGEE) 2017AJ....154...94M
    Atypical Mg-poor Milky Way Field Stars with Globular Cluster Second-generation-like Chemical Patterns 2017ApJ...846L...2F
    The open cluster King 1 in the second quadrant 2017MNRAS.470.4285C
    Ultracool dwarf benchmarks with Gaia primaries 2017MNRAS.470.4885M
    The Pristine survey - I. Mining the Galaxy for the most metal-poor stars 2017MNRAS.471.2587S
    A Gemini snapshot survey for double degenerates 2017MNRAS.471.4218K
    The puzzling interpretation of NIR indices: The case of NaI2.21 2017MNRAS.472..361R
    New ultra metal-poor stars from SDSS: follow-up GTC medium-resolution spectroscopy 2017A&A...604A...9A
    WHT follow-up observations of extremely metal-poor stars identified from SDSS and LAMOST 2017A&A...605A..40A
    Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe 2017AJ....154...28B
    The Gaia-ESO Survey: Low-α element stars in the Galactic bulge 2017A&A...602L..14R
    Gaia Data Release 1. Open cluster astrometry: performance, limitations, and future prospects 2017A&A...601A..19G
    Monitoring luminous yellow massive stars in M 33: new yellow hypergiant candidates 2017A&A...601A..76K
    The Correlation between Mixing Length and Metallicity on the Giant Branch: Implications for Ages in the Gaia Era 2017ApJ...840...17T
    Timing the Evolution of the Galactic Disk with NGC 6791: An Open Cluster with Peculiar High-α Chemistry as Seen by APOGEE 2017ApJ...842...49L
    Four new massive pulsating white dwarfs including an ultramassive DAV 2017MNRAS.468..239C
    Baade's window and APOGEE. Metallicities, ages, and chemical abundances 2017A&A...600A..14S
    Chemical tagging with APOGEE: discovery of a large population of N-rich stars in the inner Galaxy 2017MNRAS.465..501S
    Chemical Abundances of M-dwarfs from the APOGEE Survey. I. The Exoplanet Hosting Stars Kepler-138 and Kepler-186 2017ApJ...835..239S
    The Gaia-ESO Survey: Calibration strategy 2017A&A...598A...5P
    NLTE Analysis of High-resolution H-band Spectra. II. Neutral Magnesium 2017ApJ...835...90Z
    Chemical trends in the Galactic halo from APOGEE data 2017MNRAS.465.1586F
    Galactic archaeology with asteroseismology and spectroscopy: Red giants observed by CoRoT and APOGEE 2017A&A...597A..30A
    IMF and [Na/Fe] abundance ratios from optical and NIR spectral features in early-type galaxies 2017MNRAS.464.3597L
    Evidence for a metal-poor population in the inner Galactic bulge 2015A&A...584A..45S
    The SDSS-III APOGEE Spectral Line List for H-band Spectroscopy 2015ApJS..221...24S
    The Data Reduction Pipeline for the Apache Point Observatory Galactic Evolution Experiment 2015AJ....150..173N
    The Gaia-ESO Survey: chemical signatures of rocky accretion in a young solar-type star 2015A&A...582L...6S
    Abundances, Stellar Parameters, and Spectra from the SDSS-III/APOGEE Survey 2015AJ....150..148H
    The Eleventh and Twelfth Data Releases of the Sloan Digital Sky Survey: Final Data from SDSS-III 2015ApJS..219...12A
    The Gaia-ESO Survey: Empirical determination of the precision of stellar radial velocities and projected rotation velocities 2015A&A...580A..75J

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