Anne’s Image of the Day: Planetary Nebula Henize 2-47

read more at Anne’s Astronomy News http://annesastronomynews.com/

July 5, 2013

Henize 2-47, a planetary nebula in Carina

Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)

Henize 2-47 (He(n) 2-47 for short and nicknamed the Starfish Nebula because of its shape) is a young bipolar planetary nebula of barely a quarter of light-year across located within our Milky Way Galaxy, about 6,600 light-years away from Earth in the southern constellation of Carina (the Keel), while it is approaching us at approximately 17.7 kilometers per second.

Despite their name, planetary nebulae a have nothing to do with planets. The name of planetary nebulae arose in the 18th century because of the visual similarity between some round planetary nebulae and the planets Uranus and Neptune when viewed through small optical telescopes. The name has stuck even though modern telescopes make it obvious that these objects are not planets at all.

When a star with a mass up to eight times that of the Sun runs out of fuel at the end of its life, it blows off its outer shells and begins to lose mass. This allows the hot, inner core of the star (collapsing from a red giant to a white dwarf) to radiate strongly, causing this outward-moving cocoon of gas to glow brightly. Like snowflakes, planetary nebulae show a wide variety of shapes, indicative of the complex processes that occur at the end of stellar life.

Planetary nebulae last for only about 10,000 years, a fleeting episode in the 10-billion-year lifespan of Sun-like stars. So, over the next several thousand years, Henize 2-47 will gradually disperse into space, and then the white dwarf will cool and fade away for billions of years. Our own Sun is expected to undergo a similar fate, but fortunately this will not occur until some 5 billion years from now.

Henize 2-47 contains six lobes of gas and dust – resembling the legs of a starfish – which have been produced fairly recently (a few hundred years ago). The multiple lobes suggest that the central star of the nebula ejected material at least three times in three different directions. Each time, the star fired off a narrow pair of opposite jets of gas, eventually giving the nebula the shape it has at present.

This image is taken in February 2007 with the Wide Field Planetary Camera 2 onboard the Hubble Space Telescope, using three different color filters.

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