[Alumnos] Ciclo de Coloquios del IAR (fwd)

[Secretaria Academica FCAG]

  Ciclo de Coloquios del IAR


Ciclo de Coloquios en el IAR   Fecha:     Miercoles 26 de Octubre de 2011    13:30hs en el
Aula de Conferencias del IAR   Título:     "Orion BN/KL: A laboratory for high-mass star
formation"   Expositor:     Dr. Ciriaco Goddi                     (Garching, ESO)   Resumen:
The details of how massive stars form are poorly known. Orion BN/KL is the closest known
region with ongoing massive star formation, and hence offers unique chances for a detailed
study. Despite being considered an archetype, it is still poorly understood. I will review
recent work which has resolved long-standing debates on this enigmatic region, focusing on
three different aspects.
First, I will report on a monitoring of different SiO maser transitions at 7mm over several
years with the VLBA and VLA toward the massive radio source-I, which provided us with the 3D
dynamics of circumstellar gas and enabled for the first time to resolve outflow at/near launch
(<100 AU) and collimation (100-1000 AU) and demonstrate ongoing disk-mediated accretion in a
high-mass protostar.
Second, I will describe a reconstruction of the recent dynamical history of the region based
on proper motions of radio sources, which show that protostars Source I and BN (4000 AU apart)
must have experienced a close passage [O(50 AU)] 500 years ago. N-body numerical simulations
show that the dynamical interaction between a binary of 20 Solar mass (Source I) and a single
star of 10 solar mass (BN) may lead to ejection of both and binary hardening, while preserving
the original circumbinary disk around Source I (and possibly triggering ejection of the
explosive BN/KL flow).
Finally, I will briefly present the hypothesis of external heating of the eponymous Orion Hot
Core by shocks produced by Source-I?s outflow, based on recent observations of high-energy
transitions of ammonia. A better understanding of Orion BN/KL allows to advance our
understanding of high-mass star formation.