The naked T Tauri stars - The low-mass pre-main sequence unveiled

The author discusses the search for low-mass pre-main-sequence (PMS) stars associated with X-ray sources in regions of star formation. The survey to date has revealed at least 30 low-mass PMS stars in the Taurus-Auriga region, and a comparable number in Ophiuchus. These stars are the naked T Tauri stars, unveiled versions of the well-known classical T Tauri stars. The author discusses the properties of these newly discovered PMS stars and their relation to the classical T Tauri stars. He concludes that the naked T Tauri stars are the true low-mass PMS stars, and that the observable characteristics defining the classical T Tauri stars are due to the interaction of an underlying, fairly normal star with a dominant circumstellar environment. He discusses the impact the naked T Tauri stars are likely to have on our understanding of the PMS evolution of low-mass stars.