Image of the Day: Hubble Captures a Ghostly Pinwheel Nebula

This spooky image expanding pinwheel spiral shows a rare binary system called LL Pegasi and a surrounding "pre-planetary nebula" known as IRAS 23166+1655. This striking pattern is formed by material being ejected from a dying staralong with a second star — a binary partner — orbiting with it and modulating the expanding gas. Hubble captured LL Pegasi from above, so as the stars orbit, we can see a perfect gas spiral expand into space.

In this image, the central stars cannot be seen as they are smothered in obscuring material belching from the dying star, but the nebula has only just started to form.

According to the Hubble's experts, the gas is being flung into space at a speed of 50,000 km/hour (about 30,000 miles/hour) and astronomers have calculated that the two stars must be orbiting each other with a period of 800 years.

Although these spiral phenomena are rare, several pinwheel spirals are known, perhaps the most infamous being the spiral generated by WR 104. WR 104 is a Wolf-Rayet star — far more massive than the dying star in LL Pegasi — also releasing gas into space during the final stages of its life, but it's not forming a comparatively peaceful planetary nebula.

As WR 104 is so massive, its Wolf-Rayet phase is frenzied and violent, potentially resulting in a powerful gamma-ray burst (GRB) that Earth could be "peering" down the barrel of a potentially devastating GRB should it explode.

Wr104 (1)

Images via NASA/Hubble 


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