Whether you call them YSOs (Young Stellar Objects) or PMS (Pre-Main Sequence Stars) you'll find everything you wanted to know about them - and probably a few things you didn't - here. The YSO section is the newest of the AAVSO's official observing sections, and so this is the starting point for those of you who wish to observe these fascinating objects, which are becoming increasingly important to professional astronomers, since they can tell us not only about the formation of stars but also of planetary systems, plus much else besides.
May 17, 2010: Dr. Michael Sitko (U. Cincinnati) requests observations of the young stellar object TW Hya in support of upcoming Hubble Space Telescope observations. TW Hya is believed to be a T Tauri star that varies between magnitudes 10.5 and 12.2. TW Hya will be observed with the HST STIS instrument as part of a larger program to study the properties of potentially planet-forming disks around young stars. The star will be observed in the ultraviolet to search for time-variability in the gas in the inner accretion disk.
August 1, 2013: Dr. Hans Moritz Guenther (Harvard-Smithsonian Center for Astrophysics) has requested nightly observations of the classical T Tauri star AA Tau in order to schedule x-ray observations with XMM-Newton that have been planned for between 2013 August 15 and September 15.
January 16, 2013: Dr. Péter Ábrahám (Konkoly Observatory, Budapest, Hungary) has requested the assistance of AAVSO observers in monitoring eight young stars in Chamaeleon in support of photometry he and his colleagues will be obtaining with the VLT/ISAAC (infrared) and Herschel Space Observatory (far-infrared) during January-February 2013.
February 15, 2011: Dr. Colin Aspin (U. Hawaii) has requested archival images and other observations of the FU Orionis variable V1647 Ori and the surrounding field over the previous 10 years in support of a study of this star. Aspin writes that he is hoping to obtain more data with which to create a multi-year light curve of this star to put present-day observations in context of its past behavior.
November 23, 2010: The AAVSO requests ground-based observations of the Trapezium region of the Orion Nebula (M42), along with surrounding regions in Orion, in conjunction with upcoming observations with the MOST Satellite. All AAVSO observers are encouraged to participate in this project, and we are requesting observations for a number of different targets from both instrumental and visual observers.
October 1, 2010: Dr. Colin Aspin (U. Hawai'i) has requested the help of AAVSO observers in performing long-term photometric monitoring of the two new young stellar objects (YSOs) in Cygnus, HBC 722 and VSX J205126.1+440523 (see AAVSO Special Notice #216).