Astronomy Picture of the Day
    


The Extraordinary Spiral in LL Pegasi
<< Yesterday 11.12.2016 Tomorrow >>
The Extraordinary Spiral in LL Pegasi
Credit & Copyright: ESA, Hubble, R. Sahai (JPL), NASA
Explanation: What created the strange spiral structure on the left? No one is sure, although it is likely related to a star in a binary star system entering the planetary nebula phase, when its outer atmosphere is ejected. The huge spiral spans about a third of a light year across and, winding four or five complete turns, has a regularity that is without precedent. Given the expansion rate of the spiral gas, a new layer must appear about every 800 years, a close match to the time it takes for the two stars to orbit each other. The star system that created it is most commonly known as LL Pegasi, but also AFGL 3068. The unusual structure itself has been cataloged as IRAS 23166+1655. The featured image was taken in near-infrared light by the Hubble Space Telescope. Why the spiral glows is itself a mystery, with a leading hypothesis being illumination by light reflected from nearby stars.

January
February
March
April
May
June
July
August
September
October
November
December
 < December 2016  >
Mo Tu We Th Fr Sa Su



1234
567891011
12131415161718
19202122232425
262728293031
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.

Based on Astronomy Picture Of the Day

Publications with keywords: planetary nebula
Publications with words: planetary nebula
See also:
All publications on this topic >>