Facts

Contact person:
Henrik Hartman
Financers:
  • Vetenskapsrådet
Responsible at Malmö University:
Henrik Hartman
Project members:
Affiliate:
  • Hampus Nilsson - Lunds universitet
Time frame:
01 January 2017 - 31 December 2021
Faculty/department:

About the project

The aim of our program on Experimental and Computational Atomic Astrophysics is to provide the astronomical community with critically evaluated, high-precision atomic data to allow for accurate astrophysical conclusions in a number of fields. The conclusions should no be obscured by lacking or uncertain atomic data.

Our project responds to demands from the new directions, e.g. the near-IR domain and improved stellar atmosphere models, and large infrared investmentswithin astronomy. Based on our success in experimental atomic astrophysics, we expand activities to include state-of-the-art atomic calculations to provide the astronomical community with complete sets of crucial atomic data. These data include energy levels and wavelengths for line identification, oscillator strengths and transition rates for quantitative analyses and line structures such as isotopic and hyperfine parameters for detailed spectral modelling.

A recent editorial text in the Nature magazine pointed out the urgent need for atomic data: ’Lab spectroscopy has long lagged behind telescope observations, but it is striking just how wide the gap has now grown’ specifically mentioning oscillator strengths 1.

A limiting factor in the analysis of the extensive and expensive astronomical observations is thus the lack, or absence, of accurate atomic data. We meet this huge challenge with a detailed knowledge in atomic structure and techniques stretching from large scale atomic calculations to laboratory experiments in connection with strong collaborations with observational astronomy.

Within this broader purpose, we divide the specific aims of the program in three different topics:

  • Accurate wavelengths and level energies: The basic information for atomic transitions is the wavelength. In the infrared, the wavelengths for many elements are not known accurate enough for line identifications.
  • Transition rates and oscillator strengths (log gf): The intrinsic strength, so called transition probability or oscillator strength (log gf) ismissing for most near-IR atomic transitions, hindering abundance analysis.
  • Line profiles - isotope and hyperfine structures: Hyperfine structure (hfs) is an important intrinsic line broadening, which must be correctly included for odd-Z elements for a correct analysis.

Each specific set of parameters is derived using a combination of different methods, experimental and computational, depending on the nature of the problem. Our strength in this sense is the broad range of well-suited methods and techniques available.