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The Hubble Heritage image of IC 4406 was constructed from two separate views with the WFPC2 camera. The two pieces were "stitched" together to form a single image showing the entire nebula.


First Image


Second Image


The Combined Image

1.What created the dust lanes?

These were created at the boundary between the visible (ionized) gas and the surrounding cloak of invisible (neutral) material. An instability mechanism operates there. The most familiar type of instability is the one that produces those white puffy cumulus clouds or thunderheads on a summer day. The instability causing the dust lanes is a different type, one recognized only about 10 years ago and named the Vishniac instability (after its discoverer, the astrophysics theoretician Ethan Vishniac). In the Vishniac instability material is moved laterally across a surface, concentrating into local spots. This is much like puddles forming on a prairie after a rain, i.e. small local variations in the surface cause the material to concentrate in specific areas. Once concentrated, the neutral material is dense enough to become visible in silhouette. These are the dark lanes.

2.Would we really be able to see IC 4406
without Hubble's power and filtering capabilities?

Yes. We can see the object from the ground. The object has an IC number (Index Catalog), indicating that it was first seen and recorded in the 19th century. What the HST has allowed us to do is to see the object in much greater detail and to figure out its 3-D structure.


*Questions were done by Rob Britt from Space.com and answers by C.R. O'dell*