Celestial hemisphere:  Southern  ·  Constellation: Aquarius (Aqr)  ·  Contains:  Helix Nebula  ·  NGC 7293  ·  PGC 833621  ·  PGC 833917  ·  PGC 834421  ·  PGC 835051  ·  PGC 835085  ·  PGC 837430  ·  PGC 838266  ·  PK036-57.1
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NGC 7293, Gary Imm
NGC 7293, Gary Imm

NGC 7293

Getting plate-solving status, please wait...
NGC 7293, Gary Imm
NGC 7293, Gary Imm

NGC 7293

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Description

This object, also known as the Helix Nebula, is a planetary nebula located only 650 light years away in the constellation of Aquarius at a declination of -21 degrees. Also known as the Eye of God, this is one of the closest to Earth of all the bright planetary nebulae. Its apparent size is about half the diameter of the full moon, with an actual diameter of about 2.5 light-years.

Planetary nebula are intermediate sized stars, like our sun, which shed and illuminate their outer layers of gas near the end of their life. The progenitor star in this case is the small central bluish star, which is destined to become a white dwarf.

This object has many radial filaments around the circumference, all pointing back to the central star. These filaments are likely gaseous streams ejected from this star. Many of these filaments resolve into cometary knots. Some of these knots are visible in the image as tiny puffs of white clouds along the outer edge of the bluish core. The knots look tiny but each are larger than our solar system.

Many different explanations have been proposed over the years for the morphological structure of this nebula, including 2 overlapping rings or a doughnut. The one which makes the most sense to me is a bi-polar structure with 2 spherical lobes expanding from the central star, constricted by a toroidal ring of dust and gas around its equator. The white region, appearing as almost a circular ring in the image, is the part of the nebula constricted by the toroidal ring. The major axis of the structure is oriented from 8 o’clock to 2 o’clock. We are looking at the nebula at an angle of about 35 degrees from end-on. There is some lobe breakout at each end of the nebula, where the reddish outer nebula is seen to come to a point. This gives the nebula its “eye” shape.

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