|One of the most amazing geometrical forms in outer space, the nebula IRAS 23166+1655 is centered on a hidden star in the early stages of becoming a planetary nebula. Photo taken by the Hubble Space Telescope. Credit: NASA/ESA|
Their period of revolution about one another closely matches the age of each shell in the pinwheel. One of the stars is a red giant called a carbon star because its atmosphere is rich in carbon formed through the fusion of helium in the star’s core. Numerous sun-like stars pass through a giant phase in their evolution when they lose mass from their atmospheres into space. In this case, the star sloughs off material at the rate of 1/100,000 of the sun’s mass each year or an entire sun’s worth over 100,000 years. The companion star is hotter and bluer and revolves around the giant. The gravitational interaction of the giant and its companion during their 800-year revolution channels some of the giant’s gas and dust into an expanding shell. Over many millennia, a series of concentric layers are spun out. I count five separate shells which adds up to 800 x 5 or 4000 years this gem’s been in the making.
You may be wondering why we should see the spiral nebula at all if the stars that form it are hidden behind dust. Astronomers propose that the nebula is being illuminated by galactic starlight. The dense plane of the galaxy, where stars are concentrated, is off to the right. That also happens to be the brightest part of the spiral. It all makes sense in a wonderfully natural way.
This entire post was blatantly stolen from HERE. A great blog.
Astro Bob blog: This can't be real, but it is
An amazing natural phenomenon in outer space catches astronomers' attention.
By: Bob King, Duluth News Tribune
"Let's all be careful out there!"