2006 Annual Science Report
University of Hawaii, Manoa Reporting | JUL 2005 – JUN 2006
Variable Young Stellar Objects Survey
Young stars undergo major changes during their evolution towards the main sequence. Additionally, the presence of a circumstellar accretion disk and its magnetic coupling to the central star leads to constant perturbations. It is therefore not a major surprise that virtually all young stars are variable, although amplitudes and timescales differ from one type to another, and depend as well on the evolutionary stage. It is becoming increasingly understood and appreciated that the rather static view of pre-main sequence evolution that has prevailed for many years is misleading, and that young stars cannot be understood without taking their continuous changes into account. Indeed, time-dependent phenomena may hold the key to an understanding of the way young stars grow and their circumstellar environments evolve, eventually leading to the formation of planetary systems.
The major effort during the past year has been to prepare the VYSOS project. VYSOS (Variable Young Stellar Objects Survey) consists of twin 16 inch telescopes, one mounted in Hawaii at Mauna Loa and the other in Chile at Cerro Armazones. The northern telescope is owned and operated by B. Reipurth, and the southern telescope is owned and operated by Rolf Chini, a colleague at the Ruhr-Universitat Bochum in Germany. The goal of the project is to have these two fully robotic telescopes monitor all star forming regions along the entire Galactic plane within about 2 kpc in order to understand the photometric variability of solar-like young stars. Such variability can have a number of causes, mainly accretion activity, star spots, eclipses by companions or dust clouds, and magnetic reconnection events. Almost nothing is known about the timescales and amplitudes of these phenomena, and the VYSOS project will put this on a firm footing by monitoring many tens of thousands of young low-mass stars over the next decade or more.
Both telescopes have been constructed by Equinox, Inc., an optical engineering company in Colorado. The installation of the northern telescope has just been completed and the hardware tested, while the southern telescope will be installed in September 2006. We have invested major efforts to develop advanced software packages that will automatically reduce the images and produce a catalogue of all observed stars, which will amount to several million targets, including unrelated stars along the line of sight. We have developed a complete telescope control system, and we are presently working on a target selection and scheduling program. The VYSOS project is the most ambitious effort that has ever been made to characterize the synoptic behavior of young low-mass stars, and thus to understand the energetic events that flooded the environment of the early Sun before and during its planet forming phase.