Research

Our research interests can be categorized into Star Formation, The Young Sun and Early Planetary Evolution and Stellar Magnetic Activity:

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?	New Surveys of Star-Forming Regions Hot Bubbles in Star-Forming Regions Gas and Dust Disks and the Gas-to-Dust Ratio X-Ray Jets Accretion onto T Tauri Stars and Brown Dwarfs X-Ray Soft Excess in Classical T Tauri StarsHerbig Ae/Be Stars The Structure of T Tauri Magnetospheres

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