Our recent studies on isotope anomalies in planetary atmospheres, especially in Titan's atmosphere show an indication that our early Sun underwent during the first 600 million years after its origin a very active period which is called Post-T-Tauri phase.
We investigate the particle and radiation environment during such an early solar period, where the solar wind particle density and soft x-ray flux is up to 1000 times higher than at present. We cooperate in our study with colleagues from the Sun in time project, and use a of nine solar like G-type stars with an age between 70 million and 9 billion years.
The physical parameters from these stars were obtained by observations with the ROSAT and ASCA x-ray satellites.
Our study investigates: