Sun Kwok

Review by Joe Benderavage, March 2006.
Cosmic Butterflies, by Sun Kwok, 2001, Cambridge
University Press, Cambridge, UK is currently available
for loan in our club library. This is a beautiful and
exciting tome. I found I could not put it down, over
the course of two days, until I had finished it.
One of the early chapters contains a scenario of our
sun becoming a planetary nebula: what would it be
like inside an expanding planetary nebula, Kwok asks
rhetorically. The answer is surprising, and worth
reading.
Kwok deals with symmetrical nebulae in the major
portion of the book. Vital statistics of a typical
planetary nebula (PN) come in following chapters.
PN origins lie in stars called “asymptotic giant branch”
stars that are redder and more luminous than the usual
red giant stars. In 1977, at a farm in Erin, Ontario,
Chris Purton, Pim Fitzgerald, and the author, Sun
Kwok, devised a theory for PN formation, better
known as the “interacting winds” theory, which dealt
with slow stellar winds ejecting massive amounts of
the stellar atmosphere into an envelope surrounding
the asymptotic giant red star. Later, a separate, fast
stellar wind would be “…acting as a snow plow and
sweeping up the slow wind material left over from the
asymptotic giant branch. The swept up material makes
a dense shell, which is what we traditionally call the
planetary nebula.”
Kwok includes photos that go far to substantiate the
theory. He also provides interesting and satisfying
narrative on the search for proto-planetary nebulae, a
very early stage of PNs. He also deals with the
thorny issue of asymmetrical and amorphous PNs,
extensions, handles (“ansae”), radial filaments, jets,
and NGC 2440, “…an object so complicated it defies
description”.
A surprising discovery of new forms of carbon leads
Kwok to pose the question “Do we owe our lives to
planetary nebulae?”, which he makes into the
tantalizing title of his last chapter.
This 179-page book contains over a hundred colour
photographs of planetary nebulae, with an appendix of
detailed information of the photos. It also contains
many other images, pictures, and diagrams, and has an
index, glossary, and recommended auxiliary reading
list.
The author was a Professor of Astronomy at the
University of Calgary at the time he wrote this book.
He is considered an expert on planetary nebulae.… (meer)