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Astronomy Picture of the Day 4-09-03
NASA ^ | 4-09-03 | Robert Nemiroff and Jerry Bonnell

Posted on 04/09/2003 5:32:48 AM PDT by petuniasevan

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2003 April 9
See Explanation.  Clicking on the picture will download
 the highest resolution version available.

The Egg Nebula in Polarized Light
Credit: W. Sparks (STScI) & R. Sahai (JPL), Hubble Heritage Team (STScI / AURA), NASA

Explanation: Where is the center of the unusual Egg Nebula? Like a baby chick pecking its way out of an egg, the star in the center of the Egg Nebula is casting away shells of gas and dust as it slowly transforms itself into a white dwarf star. The Egg Nebula is a rapidly evolving pre-planetary nebula spanning about one light year toward the constellation of Cygnus. Thick dust, though, blocks the center star from view, while the dust shells further out reflect light from this star. Light vibrating in the plane defined by each dust grain, the central star, and the observer is preferentially reflected, causing an effect known as polarization. Measuring the orientation of the polarized light for the Egg Nebula gives clues to location of the hidden source. The above image taken by the Advanced Camera for Surveys on the Hubble Space Telescope is false-color coded to highlight the orientation of polarization.

Have you seen this week's: HEASARC Picture of the Week?


TOPICS: Astronomy; Astronomy Picture of the Day; Science
KEYWORDS: astronomy; dust; gas; hubble; image; light; nebula; polarized; space; star; stars; telescope

"The Egg Nebula, also known as CRL 2688, is shown on the left as it appears in visible light with the Hubble Space Telescope's Wide Field and Planetary Camera 2 (WFPC2) and on the right as it appears in infrared light with Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS). Since infrared light is invisible to humans, the NICMOS image has been assigned colors to distinguish different wavelengths: blue corresponds to starlight reflected by dust particles, and red corresponds to heat radiation emitted by hot molecular hydrogen."

There is more information at the Hubble Heritage site (and a gallery of photos). Here is the link for the Egg Nebula: Egg Nebula in Polarized Light

Oh, note that the last link called "Egg Nebula" in the APOD article is a PDF file. You'll need Adobe Acrobat reader to view that page.

1 posted on 04/09/2003 5:32:48 AM PDT by petuniasevan
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To: MozartLover; Joan912; NovemberCharlie; snowfox; Dawgsquat; viligantcitizen; theDentist; ...

2 posted on 04/09/2003 5:33:59 AM PDT by petuniasevan (Non-paying FReepers: "Put your money where your mouth is!")
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3 posted on 04/09/2003 5:34:05 AM PDT by Support Free Republic (Your support keeps Free Republic going strong!)
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To: petuniasevan
Very cool!
4 posted on 04/09/2003 5:39:36 AM PDT by GodBlessRonaldReagan (where is Count Petofi when we need him most?)
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To: petuniasevan
Beautiful, thanks!
5 posted on 04/09/2003 6:04:53 AM PDT by xJones
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To: petuniasevan
Great APOD. Appropriate for the time of year. Thanks.
6 posted on 04/09/2003 7:11:07 AM PDT by foolish-one
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To: petuniasevan
Thanks for the ping (-:
7 posted on 04/09/2003 8:59:08 AM PDT by firewalk
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To: petuniasevan
Polarized light. We can measure it thanks to crystal filters. We can describe it mathematically. We can use it to see fish. But what it is, is a mystery--something to be glossed over.
8 posted on 04/09/2003 9:38:05 AM PDT by RightWhale (Theorems link concepts)
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To: petuniasevan
Although I prefer my eggs poached to polarized, that is an amazing view of the nebula...

Great work!
9 posted on 04/09/2003 11:30:36 AM PDT by mikrofon (Lawyers' motto: "Semper Fee")
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