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Star Formation

We are studying issues of star formation, in particular effects of stellar radiation and particle flows onto the stellar environment such as protostellar disks and their physical and chemical development.

Challenges Links
  • How do accretion, B fields, and high-energy radiation modify young stellar environments such as protostellar disks?
  • How and why is the gas-to-dust ratio altered around young stars?
  • How are jets heated to millions of degrees?
  • Do star-forming regions contribute to lifecycle of matter in the ISM?

The Young Sun and Early Planetary Evolution

Our work on the “young Sun” and its planetary system has focused on the Sun’s short-wavelength output, especially in the context of its evolutionary history. Principal questions addressed by this work include:

Challenges Links
  • How does the output of a star like the Sun vary during its main-sequence evolution?
  • How does enhanced short-wavelength radiation affect the planetary environments?
  • Why was the output of the young Sun up to a thousand times stronger than at present?
  • How are young stellar B fields structured?
  • Stellar Magnetic Evolution and the “Sun in Time” Project
  • Spectral Irradiance and Young Planetary Atmospheres
  • The “Faint Young Sun Paradox” and the Young Radio Sun
  • Magnetic Structure in the Young Sun

Stellar Magnetic Activity

We have worked in X-ray spectroscopy espeecially with XMM-Newton and Chandra to investigate magnetic structure of, and energy release in, stellar coronae and magnetospheres. Topics include:

Challenges Links
  • Composition of magnetized coronae;
  • Physics of energy release during explosive flares; chromospheric evaporation physics;
  • Long-term evolution of stellar atmospheres, and solar-stellar connection studies;
  • Pre-main sequence high-energy evolution.
  • The Inverse First Ionization Potential Effect
  • Coronal Spectroscopic Diagnostics
  • The Neupert Effect and Physics of Stellar Coronal Flares
  • Statistical Heating and Numerical Simulations