NOAO scientists, using the Gemini Observatory 8-meter telescope in Chile, have obtained the highest resolution image ever obtained for the planetary nebula NGC 2346. Shaped like a butterfly, or an hourglass, but known scientifically as a bipolar planetary nebula, this object is at a distance of 2300 light years from our sun in the constellation Monoceros.
The new observations of this gaseous nebula, shown in the first
figure, resolve details comparable in size to our own solar system. The
team detected previously unresolved knots and filaments of molecular
hydrogen gas - details that no other telescope on the ground or in
space, not even the Hubble Space Telescope, has been able to resolve.
Molecular hydrogen in the bipolar lobes of NGC 2346 was detected
almost 30 years ago, although previous observations suggested only a
smooth torus. This filamentary structure observed by the team matches
the mechanism they have proposed in which a hot bubble of gas
surrounding the central star breaks out and fragments the shell of
surrounding gas. The gaseous knots probably represent a common
phenomenon that occurs whenever two fluids (or gasses) of different
densities come in contact, and the lighter fluid is pushing on the
heavier fluid. This is easily seen by anyone who has ever watched
colored oil in a glass of water.
The authors have constructed computer models to understand how the
gasses are expected to interact: the accompanying movie shows how the
gas will evolve in time. As first author Arturo Manchado said, “In this
movie we show the model results in time steps up to 9000 yrs. The blue
color corresponds with the emission of the molecular hydrogen gas. The
model shows an initial toroid of cool gas at the equator. Once the
swept-up shell is highly fragmented, the toroid is no longer visible and
only the large clumps will be seen.”
NGC 2346 is a star caught in the final phases of its lifecycle. It
began life as a double star system, each companion about twice as
massive as the sun and both revolving around their common center of
gravity. The more massive of the two stars burned through its fuel
faster than its lower mass companion, expanded as a red giant, and has
now shed its outer layers to become a white dwarf star, with a present
mass between 0.3 and 0.7 solar masses. The bipolar nebula, or butterfly
shape of this planetary, has probably been sculpted by the star pair,
although this is still under study. With an orbital period of 16 days,
the two stars are closer together than the sun and Mercury. Material
spilling from the more massive star over the lifetime of the pair makes
it difficult to calculate the initial mass of the star.
The observations were taken with the new near infra-red Adaptive
Optics Imager system on the Gemini telescope during the initial testing
phase of this instrument. Adaptive optics is a novel technique that
allows for real time correction of distortions to an astronomical image
caused by the earth’s atmosphere.
The paper will appear in the Astrophysical Journal
(Authors Arturo Manchado, Letizia Stanghellini, Eva Villaver, Guillermo
García-Segura, Richard A. Shaw and D. A. García-Hernández)
NOAO is operated by Association of Universities for Research in
Astronomy Inc. (AURA) under a cooperative agreement with the National
Science Foundation.
Media Contact:
Dr. Katy Garmany
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National Optical Astronomy Observatory
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Tucson AZ 85719 USA
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E-mail: kgarmany@noao.edu
Science Contact
Dr. Letizia Stanghellini
NOAO
E-mail: lstanghellini@noao.eu
