This thesis explores the 3 dimensional behavior of the outer ejecta from the
post-red supergiant IRC +10420. This star inhabits a region of the Hertzsprung-
Russell diagram just below the Humphreys-Davidson instability limit. It also
appears to be evolving from a cooler temperature to a hotter one, making it a
very unique star. It is the only star of its type of have observed nebulosity. Images
of this star show the nebulosity, or complex ejecta that is evidence of episodic mass
loss. The transverse motions of the various features seen in the inner ejecta are
explored. This information is obtained from two sets of images taken with the
HST/WFPC2 in 1996 and 2008. Additional information from a previous paper
also gives the radial velocity for several features, allowing the determination of
the total motion for a number of the features.
Combining the radial and transverse velocity information into a time since
ejection, this gives a picture of the mass loss history, the time between ejection
epochs and the outflow from the star. Additionally, the radial velocity measurements
prove that these features are spatially distinct and that are expanding away
from the star. The motion of these features is predominantly dominated by their
transverse motion and they appear to be moving within a few degrees of the plane
of the sky. The connection between this and the magnetic fields are discussed.
This leads to the conclusion that IRC +10420 has approximate rotational symmetry
and is viewed almost pole-on, with the equatorial plane nearly in the plane
of the sky.
University of Minnesota M.S. thesis. July 2010. Major: Astrophysics. Advisor: Dr. Roberta M. Humphreys. 1 computer file (PDF); vii, 46 pages, appendix A.
Tiffany, Chelsea Lynn.
The three dimensional morphology of the circumstellar ejecta of IRC +10420..
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