[Todos] IAFE -COLOQUIOS:"Orion BN/KL: A laboratory for high-mass star formation" - Viernes 28 de octubre, 14:00 hs]

[difusion en iafe.uba.ar]

                   PRÓXIMO COLOQUIO DEL IAFE
                 Instituto de Astronomía y Física del Espacio
                           CONICET-UBA
 __________________________________________________________________
          "Orion BN/KL: A laboratory for high-mass star formation"


                         Dr. Ciriaco Goddi
      European Southern Observatory (ESO), Garching, Germany

               Viernes 28 de octubre a las 14:00hs
                     Aula del Edificio IAFE



Abstract:
 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.