What’s the Waterfall Nebula’s secret?

It’s a magnificent structure but what is it hiding from astronomers?


In the Great Orion Molecular Cloud Complex 1,500 light years away, can be found one of the most bizarre phenomena ever seen in the universe. Known by its designation Herbig-Haro 222 (HH-222), the Waterfall Nebula is astounding in its shape and has baffled astronomers the world over. The ‘stream’ extending downwards in this image is about ten light years long and contains an unusual range of colours, possibly due to the interaction of a young star with a molecular cloud.

The most unusual characteristic of this nebula is the concentration of radio sources in its upper left portion. It might be that the origins of the ‘stream’ are a binary system containing a hot white dwarf, neutron star or black hole, with the waterfall being a jet of radiation emitted from this system. However, our understanding of these binary systems dictates that they should contain a large amount of X-rays. For the Waterfall Nebula this is not the case, so further studies will be needed to truly understand what’s going on.

One thing we do know a little about is the red jet that can be seen near the ‘base’ of the waterfall. Called Herbig-Haro 34 (HH-34), it is thought to be a protostar – a star that has just been born. The brighter areas within it signify regions where matter is slamming together and heating up. The vivid balls of energy within this jet are being ejected from the star at a speed of around 250 kilometres per second (155 miles per second) into the surrounding interstellar dust. The rest of the Waterfall Nebula, however, will remain a mystery for now.

Image Credit: NASA

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