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IC  4406
Imaged by Martin S. Ferlito copyright
Gstar-EX Integrating Video Camera
8" SCmidt-Cassegrain on Vixen GP Mount, Stepper Driven.
Information provided by heritage.stsci.edu

A dying star, IC 4406, dubbed the "Retina Nebula" is revealed in this month's Hubble Heritage image. Like many other so-called planetary nebulae, IC 4406 exhibits a high degree of symmetry; the left and right halves of the Hubble image are nearly mirror images of the other. If we could fly around IC4406 in a starship, we would see that the gas and dust form a vast doughnut of material streaming outward from the dying star. From Earth, we are viewing the doughnut from the side. This side view allows us to see the intricate tendrils of dust that have been compared to the eye's retina. In other planetary nebulae, like the Ring Nebula (NGC 6720), we view the doughnut from the top.

One of the most interesting features of IC 4406 is the irregular lattice of dark lanes that criss-cross the center of the nebula. These lanes are about 160 astronomical units wide (1 astronomical unit is the distance between the Earth and Sun). They are located right at the boundary between the hot glowing gas that produces the visual light imaged here and the neutral gas seen with radio telescopes. We see the lanes in silhouette because they have a density of dust and gas that is a thousand times higher than the rest of the
nebula. The dust lanes are like a rather open mesh veil that has been wrapped around the bright doughnut. 



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