What was the atmosphere of the Earth like after the sun went through the T- Tauri stage?
This is hard to estimate because it depends on what you think the formation process was. An older view was that it might have been rich in methane, ammonia, water and other gaseous compounds we know about from studies of interstellar clouds. These compounds are also found in comets. Comets, or similar bodies, may even have been the primary delivery vehicle for these volatile compounds. The solid earth may either have formed cold, but as it grew larger the action of trapped radioactive nuclides decaying heated the interior up. Large 500 – 1000 km bodies impacting the surface probably left the surface in a near-molten state with a surface temperature of thousands of degrees. These impacts probably continued well beyond the T-Tauri turn-on stage of the sun which happened about 10 million years after the initial cloud collapse. The estimates I know about suggest that the T-Tauri wind was powerful enough to strip away any primordial atmospheres that existed leaving the earth a naked ball of
