by Peter Michaud
Gemini Images:
A Planetary Nebula of
Uncertain Parentage
A new Legacy Image from the Gemini Observatory reveals the remarkable
complexity of the planetary nebula Sharpless 2-71 (Sh 2-71). Embroiled in a bit
of controversy over its “birth parents” the nebula likely resulted from interactions
between a pair of two old and dying stars. Legacy images like this one share the
stunning beauty of the universe as revealed by the twin 8-meter Gemini telescopes
in Hawai‘i and Chile.
Often what seems obvious isn’t.
Take this new Gemini Legacy Image of the elaborate planetary nebula Sharpless 2-71. For most
of its recorded history, astronomers assumed that it formed from the death throes of an obvious bright star (a known binary system) near its center. Arguments against that claim, however,
have turned this case into a classic mystery of uncertain parentage.
The Gemini Legacy Image shows the long-assumed central star shining as the brightest object
very close to the center of the nebula’s beautiful gas shell. But new observations have shown
that the nature of a dimmer, bluer star — just to the right, and a bit lower than the obvious
central star — might provide a better fit for the nebula’s “birth parent.”
The uncertainty arises from the fact that the brighter central star doesn’t appear to radiate
enough high-energy (ultraviolet) light to cause the surrounding gas to glow as intensely as it
does, whereas the dimmer, bluer star likely does. On the other hand, the brighter star’s binary
nature would help explain the nebula’s asymmetrical structure. Astronomers do not yet known
if the dimmer, bluer star also has a companion.
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GeminiFocus
June2012