Minkowski 2-9, abbreviated M2-9 (also known as Minkowski's Butterfly, Twin Jet Nebula, the Wings of a Butterfly Nebula, or just Butterfly Nebula) is a
planetary nebula that was discovered by
Rudolph Minkowski in 1947. It is located about 2,100
light-years away from Earth in the direction of the constellation
Ophiuchus. This
bipolar nebula takes the peculiar form of twin
lobes
Lobe may refer to:
People with the name
* Lobe (surname)
Science and healthcare
* Lobe (anatomy)
* Lobe, a large-scale structure of a radio galaxy
* Glacial lobe, a lobe-shaped glacier
* Lobation, a characteristic of the nucleus of certain ...
of material that emanate from a
central star.
Astronomers have dubbed this object as the ''Twin Jet Nebula'' because of the
jets believed to cause the shape of the lobes. Its form also resembles the wings of a
butterfly. The nebula was imaged by the
Hubble Space Telescope in the 1990s.
The primary component of the central binary is the hot core of a star that reached the end of its main-sequence life cycle, ejected most of its outer layers and became a
red giant
A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around or ...
, and is now contracting into a
white dwarf. It is believed to have been a sun-like star early in its life. The second, smaller star of the binary orbits very closely and may even have been engulfed by the other's expanding stellar atmosphere with the resulting interaction creating the nebula. Astronomers theorize that the gravity of one star pulls some of the gas from the surface of the other and flings it into a thin, dense disk extending into space. As the central binary orbits with a period of about 86 to 120 years, the wind emitting from the binary changes direction with it.
The nebula has inflated dramatically
due to a fast
stellar wind
A stellar wind is a flow of gas ejected from the upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spherically symmetric.
D ...
, blowing out into the surrounding disk and inflating the large, wispy
hourglass-shaped wings perpendicular to the disk. These wings produce the butterfly appearance when seen in projection. The outer shell is estimated to be about 1,200 years old .
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Notes
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{{sky, 17, 05, 37.95, -, 10, 08, 34.58, 2100
Planetary nebulae
Ophiuchus (constellation)
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