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NGC 6302 - the "bug" or butterfly nebula, a planetary nebula
in the constellation Scorpion |
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Object description:
NGC 6302 is a bipolar planetary nebula in the
constellation Scorpio. About 130 bipolar planetary nebulae are known in our
Milky Way at the moment. Because of its appearance, it also wears the more
common names Bug or Butterfly Nebula.
NGC 6302 stands at a distance of
approx. 3,800 light years from our solar system with an apparent size in the
sky of only 120 x 85 arc seconds. It was discovered by the Scottish astronomer
J. Dunlop in June 1826.
« Click here or the thumbnail image for a comparison with the
size of the Moon |
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Like all
planetary nebulae, it is the result of a star that has reached the end of its
life. After the star inflated to a red giant star, the gases of the outer star
shell were ejected into the surrounding space.
The star - HD 155 520 -
originally had about 5 solar masses, of which now about 4.4 solar masses are in
the nebula. The star itself is not visible in the visual spectral band, it is
hidden behind the dark, dusty and disc-shaped structure perpendicular to the
"butterfly". In other spectral bands the star itself can be observed and the
investigations show that it now only has a mass of about 0.64 solar masses.
With a temperature of about 400,000 degrees Celsius it is one of the hottest
stars in our galaxy. The resulting extremely strong UV radiation ionizes the
atoms of the nebula and, depending on the chemical elements, makes them glow in
different colours. |
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The
gas masses of the "butterfly" are with very hot (about 30,000 degrees Celsius)
compared to other bipolar planetary nebulae and move with the extremely high
speed of about 1 million kilometres per hour away from the star. With this
speed, the distance between Earth and Moon will be covered in 24
minutes.
Based on these values, the ejection of the gas masses began
only 2,200 years ago, the dark dust torus is much older with about 6,000 years.
NGC 6302 is one of the most complex and one of the youngest planetary nebulae
in the Milky Way. Its size is about 2 light years, which is half the distance
between the Sun and the nearest fix star alpha
Centauri.
The first scientific
investigations were carried out by E. E. Barnard in the year 1907. In 2009, NGC
6302 was photographed in very high resolution by the
Hubble Space Telescope in various narrow spectral bands and
combined to the adjacent colour image. |
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