Title:Stars in adolescence: wild accretion, manic depression, fits of irrational outbursts, and

pimply spots

Speaker: Greg Herczeg (KIAA)

Time: Thursday, 3:00pm, June 26

Location: Lecture Hall, 3rd floor

　　Abstract: Classical T Tauri stars are the adolescents of stellar evolution. They are nearly fully formed, with a remnant disk and ongoing accretion that usually lasts 2 - 5 Myr. Some stars refuse to grow up, taking as long as 10 Myr before losing their disks and emerging toward maturity. Strong magnetic activity leads to pimply spots on the stellar surfaces. Some T Tauri stars are still hidden inside their disks, not yet ready to emerge. Manic mood swings change the appearance of the star and are often explained with stochastic accretion. Depression has been seen in lightcurves on timescales of days to years. Sometimes every classical T Tauri star seems as uniquely precious as a snowflake, but all stars ultimately emerge from this wild period into the uniformity of adulthood. I will describe the physics that drives the evolution from birth to adulthood, efforts to understand the stellar properties despite the wild teenage facade, and recent observations that are starting to reveal how planets form in circumstellar disks around adolescent stars.