Giovedì 23  ottobre alle ore 15:00, la Dott.ssa Lara Piscarreta (ESO – Garching, Germany) terrà il seminario dal titolo “Probing accretion and stellar properties in the Orion Nebula with VLT/X-Shooter”.

Abstract:
As the environments where planets form, protoplanetary disks provide fundamental insights into the conditions for planet formation. Particularly, the timescale of disk dispersal defines the time window available for planets to form and is typically observed to be ~2-3 Myr. Yet, several photometric studies have identified pre-main-sequence (PMS) stars still accreting from their disk at apparent ages >10 Myr in optical color-magnitude diagrams (CMDs). The Orion Nebula (~400 pc), the nearest massive star-forming region, seems to host such apparently old accretors. Most spectroscopic accretion surveys, however, focus on nearby, low-density regions; a homogeneous analysis in the Orion Nebula, which also better represents where most stars (and planetary systems) form, has been lacking. Motivated by this, we obtained VLT/X-Shooter spectra of 40 PMS stars in the Orion Nebula spanning isochronal ages from ~1 to >30 Myr. Using a multi-component fitting procedure that simultaneously models photospheric emission, accretion continuum excess, and extinction, we derived stellar parameters, accretion parameters, and extinction in a self-consistent way. In this talk, I will present our Orion Nebula accretion dataset, the methodology needed to interpret optical CMD positions, and comparisons with nearby, less dense star-forming regions.