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

    APOGEE detection of N-rich stars in the tidal tails of Palomar 5 2022MNRAS.510.3727P
    A stellar stream remnant of a globular cluster below the metallicity floor 2022Natur.601...45M
    J-PLUS: Searching for very metal-poor star candidates using the SPEEM pipeline 2022A&A...657A..35G
    Retrieving the transmission spectrum of HD 209458b using CHOCOLATE: a new chromatic Doppler tomography technique 2022A&A...657A..23E
    The Pristine survey - XIV. Chemical analysis of two ultra-metal-poor stars 2021MNRAS.508.3068L
    Gaia Early Data Release 3. Updated radial velocities from Gaia DR2 2021A&A...653A.160S
    HD 22496 b: The first ESPRESSO stand-alone planet discovery 2021A&A...654A..60L
    The Pristine survey XIII: uncovering the very metal-poor tail of the thin disc 2021MNRAS.508.1509F
    Warm terrestrial planet with half the mass of Venus transiting a nearby star 2021A&A...653A..41D
    Symbiotic Stars in the Apache Point Observatory Galactic Evolution Experiment Survey: The Case of LIN 358 and SMC N73 (LIN 445a) 2021ApJ...918...19W
    Understanding the Angular Momentum Evolution of T Tauri and Herbig Ae/Be Stars 2021AJ....162...90P
    HiPERCAM: a quintuple-beam, high-speed optical imager on the 10.4-m Gran Telescopio Canarias 2021MNRAS.507..350D
    The Pristine survey - XII. Gemini-GRACES chemo-dynamical study of newly discovered extremely metal-poor stars in the Galaxy 2021MNRAS.506.1438K
    The Pristine Inner Galaxy Survey (PIGS) III: carbon-enhanced metal-poor stars in the bulge 2021MNRAS.505.1239A
    An extension of the MILES library with derived T<SUB>eff</SUB>, log g, [Fe/H], and [α/Fe] 2021MNRAS.505.4496G
    sMILES: a library of semi-empirical MILES stellar spectra with variable [α/Fe] abundances 2021MNRAS.504.2286K
    The APOGEE Data Release 16 Spectral Line List 2021AJ....161..254S
    Six transiting planets and a chain of Laplace resonances in TOI-178 2021A&A...649A..26L
    The pristine dwarf-galaxy survey - III. Revealing the nature of the Milky Way globular cluster Sagittarius II 2021MNRAS.503.2754L
    Probing 3D and NLTE models using APOGEE observations of globular cluster stars 2021A&A...647A..24M
    The atmosphere of HD 209458b seen with ESPRESSO. No detectable planetary absorptions at high resolution 2021A&A...647A..26C
    Analysis of Previously Classified White Dwarf-Main-sequence Binaries Using Data from the APOGEE Survey 2021AJ....161..143C
    Fundamental physics with ESPRESSO: Towards an accurate wavelength calibration for a precision test of the fine-structure constant 2021A&A...646A.144S
    ESPRESSO high-resolution transmission spectroscopy of WASP-76 b 2021A&A...646A.158T
    The GTC gains high spectral resolution 2021NatAs...5..105A
    ESPRESSO at VLT. On-sky performance and first results 2021A&A...645A..96P
    Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy 2021MNRAS.500.1385H
    The contribution of N-rich stars to the Galactic stellar halo using APOGEE red giants 2021MNRAS.500.5462H
    The S2 stream: the shreds of a primitive dwarf galaxy 2021MNRAS.500..889A
    Atmospheric Rossiter-McLaughlin effect and transmission spectroscopy of WASP-121b with ESPRESSO 2021A&A...645A..24B
    Chemical composition of the solar surface 2020JApA...41...41A
    WASP-127b: a misaligned planet with a partly cloudy atmosphere and tenuous sodium signature seen by ESPRESSO 2020A&A...644A.155A
    HADES RV programme with HARPS-N at TNG. XII. The abundance signature of M dwarf stars with planets 2020A&A...644A..68M
    Broadband transmission spectroscopy of HD 209458b with ESPRESSO: evidence for Na, TiO, or both 2020A&A...644A..51S
    The S2 stream: the shreds of a primitive dwarf galaxy 2020MNRAS.500..889A
    Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy 2020MNRAS.500.1385H
    The solar gravitational redshift from HARPS-LFC Moon spectra⋆. A test of the general theory of relativity 2020A&A...643A.146G
    The Gaia-ESO Survey: Calibrating the lithium-age relation with open clusters and associations. I. Cluster age range and initial membership selections 2020A&A...643A..71G
    Benchmark stars, benchmark spectrographs. Detailed spectroscopic comparison of ESPRESSO, PEPSI, and HARPS data for Gaia benchmark stars 2020A&A...642A.182A
    K2-111: an old system with two planets in near-resonance 2020MNRAS.499.5004M

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