APOD: 2026 August 4 Б Curious Cometary Knots in the Helix Nebula
Explanation:
What causes unusual knots of gas and dust in
planetary nebulas?
Seen also in the
Ring Nebula, the
Dumbbell Nebula and
NGC 2392,
the knots' existence was not initially predicted, and their origins are still
not well understood.
Pictured here is a fascinating image of
part of the
Helix Nebula by the
James Webb Space Telescope showing tremendous detail in
infrared light.
The cometary knots have masses similar to the
Earth but have sizes typically several times the orbit of Pluto.
One hypothesis for the fragmentation and
evolution of the knots includes existing gas being
driven out by a less dense but highly energetic
stellar wind of the central evolving star.
The Helix Nebula is one of the closest examples of a
planetary nebula created at the end of the
life of a Sun-like star.
Given a technical designation of NGC 7293, the
Helix Nebula lies about 650
light-years away towards the constellation of Water Carrier
(Aquarius).
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Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
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NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
