Figure 1.
The complex
planetary nebula
Sh2-71 as imaged
by the Gemini MultiObject Spectrograph
on Gemini North
on Mauna Kea in
Hawai‘i. The longassumed central
star is the brightest
object near the center
of the gas ring, but
evidence is building
which hints that the
much dimmer and
bluer star (just to the
right and down a bit)
might be the parent
of this beautiful
object. The image
is composed of
three narrow-band
images, and each
is assigned a color
as follows: H-alpha
(orange), HeII (blue)
and [OIII] (cyan).
Each image is 15
minutes in duration,
the field-of-view is
5.3 x 3.6 arcminutes,
and the image is
rotated 110 degrees
clockwise from north
up, east left.
Image credit:
Gemini Observatory/AURA
Another unresolved issue is whether the
brighter star’s unseen companion might be
hot enough to excite the gas to glow. If so,
this pair might be able to hold on to its parental connection to the nebula.
A research team, led by Australian astronomers David Frew and Quentin Parker (Macquarie University, Sydney) are studying the
dimmer, bluer star to understand its nature. “At
the assumed distance to the nebula (roughly
Image Background Information
Gemini’s Multi-Object Spectrograph (GMOS) captured the light of Sh2-71 in its imaging mode using filters that selectively allow specific colors of visible light to reach the detector. Each color is
produced by energized gas in the nebula glowing in a manner similar to a neon sign. Travis Rector
of the University of Alaska Anchorage assembled the data from three filters (hydrogen alpha, helium II, and oxygen III) to form the composite color image.
Planetary nebulae are the end-state of stars like our Sun. They form when old, medium-sized stars
run low on nuclear fuel, become unstable, and begin expelling their outer layers of gas into space.
Often these objects appear quite symmetrical, but when multiple stars are involved, their structure
looks much more complex. In such cases, astronomers believe that the transfer of gas from one
star to another results in explosions and eruptions that disrupt the symmetry of the nebula - as is
clearly seen in this new Gemini image.
Discovered in 1946 by Rudolph Minkowski, the nebula is located in the direction of the constellation Aquila and visible in amateur telescopes. Sh2-71 is the 71st object in a catalogue of nebulae
originally assembled by the U.S. astronomer Stewart Sharpless of the US Naval Observatory in
Flagstaff, Arizona. It is from his second catalogue, of 313 nebulae, published in 1959.
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GeminiFocus
June2012