3 items with the tag “heavy elements

  • Astrophysical Controls on the Elements of Life, Task 2: Model the Chemical and Dynamical Evolution of Massive Stars
    NAI 2009 Arizona State University Annual Report

    In order to understand the distribution of elements both on the scale of the Galaxy and individual solar systems we must understand the production of elements in stars and the dispersal of newly synthesized elements in supernova explosions. We are especially interested in the production and distribution of the radioactive isotope 26Al because the amount of this element present in the early Solar System may have affected the heating of planetesimals and hence their ability to retain water and deliver it to early planets. This task uses computational models of stellar evolution and supernovae with the most accurate treatments of physics available to predict the production elements by individual stars and by populations of stars over time.

    ROADMAP OBJECTIVES: 1.1 3.1
  • Astrophysical Controls on the Elements of Life, Task 2: Model the Chemical and Dynamical Evolution of Massive Stars
    NAI 2010 Arizona State University Annual Report

    Massive stars are the primary source for the elements heavier than hydrogen and helium on the periodic table. We are simulating the evolution of these stars and their eventual deaths in supernova explosions with state of the art physics in order to generate the most accurate estimates possible of the yields of chemical elements from both individual stars and stellar populations. We are also observing the variations of elemental abundances in nearby planet host candidates in order to determine the range of variation in bioessential elements and the effects of non-sunlike compositions on the evolution of the host stars.

    ROADMAP OBJECTIVES: 1.1 3.1
  • Astrophysical Controls on the Elements of Life, Task 2: Model the Chemical and Dynamical Evolution of Massive Stars
    NAI 2011 Arizona State University Annual Report

    The elemental ratios in stars and their planets will differ because each star has a different contributions from sources of stellar nucleosynthesis. The dominant contributions of heavy elements to molecular clouds come from supernova explosions, which may also contribute material just prior to star formation. To quantify what elements might be contributed by supernovae, in this task we first perform numerical simulations of stellar evolution, predicting how stellar properties (e.g., luminosity, temperature, internal composition, stellar winds, etc.) change over time. These results are made available to the public. We then simulate the explosions of massive stars as supernovae, to determine what elements are ejected. As a complementary study, we are also using spectra of stars, obtained during radial velocity planet searches, to find the chemical abundances of hundreds of nearby, potentially habitable stars, to assess the variability of starting compositions, and we are also modeling how the habitable zones of stars with these starting compositions might vary over time.

    ROADMAP OBJECTIVES: 1.1 3.1