Chemical Abundances in Stars

Start year
2010
Organizational Unit
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
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

Publications related

  • Gaia Data Release 2. Gaia Radial Velocity Spectrometer

    This paper presents the specification, design, and development of the Radial Velocity Spectrometer (RVS) on the European Space Agency's Gaia mission. Starting with the rationale for the full six dimensions of phase space in the dynamical modelling of the Galaxy, the scientific goals and derived top-level instrument requirements are discussed

    Cropper, M. et al.

    Advertised on:

    8
    2018
  • Lithium Abundances in nearby FGK Dwarf and Subgiant Stars: Internal Destruction, Galactic Chemical Evolution, and Exoplanets

    We derive atmospheric parameters and lithium abundances for 671 stars and include our measurements in a literature compilation of 1381 dwarf and subgiant stars. First, a "lithium desert" in the effective temperature (T eff) versus lithium abundance (A Li) plane is observed such that no stars with T eff ~= 6075 K and A Li ~= 1.8 are found. We

    Ramírez, I. et al.

    Advertised on:

    9
    2012
  • Circumstellar Material in Type Ia Supernovae via Sodium Absorption Features

    Type Ia supernovae are key tools for measuring distances on a cosmic scale. They are generally thought to be the thermonuclear explosion of an accreting white dwarf in a close binary system. The nature of the mass donor is still uncertain. In the single-degenerate model it is a main-sequence star or an evolved star, whereas in the double-degenerate

    Sternberg, A. et al.

    Advertised on:

    8
    2011

Talks related

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Conferences related

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