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April 3, 2003 09:00 AM (EST)

News Release Number: STScI-2003-09

Rainbow Image of a Dusty Star

A Hubble Heritage Release

April 3, 2003: Resembling a rippling pool illuminated by underwater lights, the Egg Nebula offers astronomers a special look at the normally invisible dust shells swaddling an aging star. These dust layers, extending over one-tenth of a light-year from the star, have an onionskin structure that forms concentric rings around the star. A thicker dust belt, running almost vertically through the image, blocks off light from the central star. Twin beams of light radiate from the hidden star and illuminate the pitch-black dust, like a flashlight shining in a smoky room.

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Q & A: Understanding the Discovery

  1. 1. What do the colors mean?

  2. The artificial "Easter-Egg" colors were used to study how light from the star reflects off smoke-sized dust particles before heading toward Earth.

    Dust in our atmosphere reflects light so that only light waves vibrating in a certain orientation are reflected toward us. This phenomenon also is true for reflections off water or roadways. Polarizing sunglasses take advantage of this effect to block out all reflections, except those that align to the polarizing filter material. It's a bit like sliding a sheet of paper under a door. The paper must be parallel to the floor to pass under the door.

    Hubble's Advanced Camera for Surveys, which snapped this image, has polarizing filters that accept light that vibrates at select angles. In this composite image, the light from one of the polarizing filters has been colored red and only admits light from about one-third of the nebula. Another polarizing filter accepts light reflected from a different swath of the nebula. This light is colored blue. Light from the final third of the nebula is from a third polarizing filter and is colored green. Some of the inner regions of the nebula appear whitish because the dust is thicker and the light is scattered many times in random directions before reaching us. (Likewise, polarizing sunglasses are less effective if the sky is very dusty).

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Credit: NASA and The Hubble Heritage Team (STScI/AURA)

Acknowledgment: W. Sparks (STScI) and R. Sahai (JPL)