Dr Nathan Smith (Centre for Astrophysics and Space Astronomy, University of Colorado)

Eta Carinae and the LBVs: Extreme Mass Loss from Luminous Evolved Stars - Dr Nathan Smith Colloquium

ATNF Marsfield Lecture Theatre

Abstract

The most prodigious mass loss for very massive stars occurs during the
Luminous Blue Variable (LBV) phase in transition to a Wolf-Rayet star,
because the most luminous hot stars never become red supergiants. The bulk
of this mass loss is a result of a few short-duration eruptions or
explosions when the star violates the classical Eddington limit, rather
than a steady wind. For the most luminous stars, these eruptions can eject
several solar masses in just a few years, and account for a large fraction
of the total post-main sequence mass loss of these stars. The mass and
geometry of their nebulae, if studied in the young free expansion phase,
can give important clues to the roles of mass loss and rotation in
steallar evolution. The most observable example of this is the nebula
around Eta Carinae, ejected only 160 years ago, which contains more than
10 Msun of material and exhibits complex bipolar geometry. Recent
high-resolution observations, especially those at IR wavelengths, are
unraveling the complex geometry, kinematics, and excitation of Eta Car's
nebula.