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ilan
09-01-2018, 12:16 PM
Hubble Sees Spectacular Cosmic Eye: NGC 3918
ScinNews Staff | 27 August 2018

NASA has released a beautiful photo snapped by the NASA/ESA Hubble Space Telescope of the planetary nebula NGC 3918.




http://cdn.sci-news.com/images/enlarge5/image_6343e-NGC-3918.jpg
This Hubble image shows the planetary nebula NGC 3918. The color image was made from separate exposures taken in the visible and near-infrared regions of the spectrum with Hubble’s Wide Field Planetary Camera 2 (WFPC2). Several filters were used to sample various wavelengths. The color results from assigning different hues to each monochromatic image associated with an individual filter. Image credit: NASA / ESA / Hubble.


NGC 3918, also known as ‘Blue Planetary’ or ‘The Southerner,’ lies in the constellation Centaurus, approximately 5,346 light-years from Earth.

This object was discovered in March 1834 by English astronomer Sir John Herschel, and is easily visible through small telescopes.

In the center of NGC 3918 are the dying remnants of a red giant star.During the final convulsive phase in the evolution of these stars, giant clouds of gas are ejected from the surface of the star before it emerges from its cocoon as a white dwarf.

The intense ultraviolet radiation from the tiny remnant star then causes the surrounding gas to glow like a fluorescent sign.

NGC 3918’s distinctive eye-like shape, with a bright inner shell of gas and a more diffuse outer shell that extends far from the nebula, looks as if it could be the result of two separate ejections of gas.

But this is in fact not the case: studies of the object suggest that they were formed at the same time, but are being blown from the star at different speeds.

The powerful jets of gas emerging from the ends of the large structure are estimated to be shooting away from the star at speeds of up to 217,500 mph (350,000 km per hour)

By the standards of astronomical phenomena, planetary nebulae like NGC 3918 are very short-lived, with a lifespan of just a few tens of thousands of years.