Poster abstract

The evolution of circumstellar discs, which contain the reservoir from which the star accretes and planets may form is heavily influenced by heating and irradiation from the central star. Photoevaporation by irradiation from the central star has been proposed as the mechanism that terminates the disc accretion phase and removes the remaining material. In this talk I will review the possible photoevaporation models and present results from our recent calculations of photoevaportion by X-rays. Young low-mass stars are strong emitters in the X-rays and can produce very large photoevaporation rates - comparable with measured accretion rates in YSOs - implying that photoevaporation will have a strong influence on the final stages of star and planet formation. I will present a results from a study that shows a simple model combining viscous evolution and X-ray photoevaporation can explain the current observations of disc evolution. Finally I will consider the implications of X-ray photoevaporation on the formation of very low mass stars.