Specific Star Forming Regions -- Oral Presentation
The HST Treasury Program on the Orion Nebula Cluster
Massimo Robberto, STScI
The HST Treasury Program on the Orion Nebula Cluster has been
completed in May 2005. It represents the largest investment of HST time
(104 orbits) ever dedicated to star formation. Using ACS, WFPC2 and NIC3
in parallel we have mapped with unprecedented sensitivity (23-24 mag),
dynamic range, spatial resolution, and spectral coverage (9 filters from
U to H) approximately 1/6 of a square degree, nearly centered on the
Trapezium stars. The survey provides the richest, most accurate and
unbiased dataset of stellar photometry for pre-main-sequence objects
ever made. Combined with optical and infrared spectroscopy from the
ground and with the data taken by Chandra (COUP) and SPITZER, it will
allow to attack key questions on star formation: PMS evolution and the
calibration of pre-main-sequence evolutionary tracks, the shape and
variations of the initial mass function in different environments, the
mass accretion rates vs. age and environment, disk evolution and dissipation
in environments dominated by hard vs. soft-UV radiation, stellar multiplicity
vs. disk fraction, planetary mass companions, etc. I will give an
overview of the program, of the observing strategy, of the data products
and present some preliminary results.