Magnetic Activity of the Atmospheres of M-type Dwarf Stars (completed)

Being the most frequent stars in the universe, dwarf stars of spectral type M ("M-dwarfs") are not only of large interest for our understanding of stars but for a wide range of topics including the chemical composition and evolution of the universe. Unfortunately, many properties of the atmospheres of these stars are poorly known.  The aim of this project was therefore the production of a small grid of 3-D models and synthetic spectra, which can be compared to data from ground-based and space-borne observatories. Work based on these models is still continued after the official end of the project.

About the project

The project “Magnetic Activity of the Atmospheres of M-type Dwarf Stars” is funded by the Research Council of Norway for the period 2011-2014. 

Summary

Dwarf stars of spectral type M, shortly referred to as “M-dwarfs”, are the most frequent stars in the universe. They are therefore of large interest for our understanding of stars, their role as host stars of extrasolar planets and for a wide range of topics including the chemical composition and evolution of the universe. Unfortunately, many properties of the atmospheres of these small and faint stars are poorly known. It is still under debate whether a global dynamo in the interior or rather a local dynamo at the surface generates the magnetic fields observed in M-dwarfs. The resulting magnetic activity is observed in form of radiation emitted from the stellar chromospheres.

Space telescopes like Kepler and the future GAIA provide high-quality data, which will allow for characterizing the properties of M-dwarf atmospheres and their activity. A systematic set of realistic theoretical models is essential for a meaningful interpretation of the observations but does not exist so far.

The primary aim of this project is therefore the production of a small grid of 3-D models and synthetic spectra, which can be compared to data from ground-based and space-borne observatories.

Objectives

Understand the distribution and generation of magnetic fields in M-dwarf atmospheres and their imprint in chromospheric diagnostics.

Methodology

  • time-dependent numerical simulations (3-D radiation magnetohydrodynamics in a local setup)
  • radiative transfer calculations for the production of stellar spectra and intensity maps
  • detailed comparison to observations


 

Published Oct. 20, 2011 11:40 AM - Last modified Jan. 28, 2016 12:33 PM

Contact

Sven Wedemeyer-Böhm

Institute of Theoretical Astrophysics

Postboks 1029 Blindern

0315 Oslo