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The NASA/ESA Hubble Space Telescope 

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with a little help from an amateur astronomer

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has produced one of the best views yet of nearby galaxy Messier 106

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a striking spiral galaxy with a number of secrets

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Hubblecast episode 62: A spiral galaxy with a secret

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Located a little over 20 million light-years away

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practically a neighbour by cosmic standards

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Messier 106 is one of the brightest and nearest spiral galaxies to our Milky Way

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Although it may not look particularly unique

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some of its features have baffled astronomers for years

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Messier 106 has a supermassive black hole at its centre

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Although this is true for most galaxies

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this black hole is particularly active and hungry

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gobbling up nearby material at a startling rate

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This huge black hole’s bottomless appetite 

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is behind much of the galaxy’s unusual behaviour

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Messier 106 appears to be emitting powerful radiation from its centre 

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something we do not see with our Milky Way

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This is caused by the very active black hole at the galaxy’s centre

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which violently drags gas and dust inwards

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This material heats up, emitting microwave and X-ray radiation as it does so

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However, this emission is not the most intriguing feature of this spiral galaxy

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This image shows the galaxy’s other not-so-hidden secret:

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alongside its two regular star-packed spiral arms

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it appears to have two more, made out of hot, glowing gas

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While these ghostly extra arms have been known about for decades

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astronomers were unsure of how they formed — until recently

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Yet again, the culprit is Messier 106’s supermassive black hole

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The extra arms are actually regions of gas

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that have been heated up to scorching temperatures of millions of degrees

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As material spins around and heats up at the galaxy’s centre

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the turbulent motion causes jets of material to shoot outwards

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The jets disrupt and heat up all the gas in their path

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which in turn excites denser gas towards the centre of the galaxy

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This gas is tightly bound together, so it remains roughly straight

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However, the looser gas further out is blown away from the jets 

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so that it curves out of the galactic plane 

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creating the arching red arms seen in this image

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These “extra” arms are very unusual, and this poses a bit of a puzzle

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because galactic jets are actually quite common

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It is not just spirals that show jets

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elliptical galaxies do too, such as the spectacular radio jets seen

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around the nearby galaxies Hercules A and Centaurus A

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And yet none of these show any of the features seen in Messier 106

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Some of the data for this image of Messier 106 were provided

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by amateur astronomer Robert Gendler

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Together with Hubble, these data allow us to visualise the galaxy’s chaotic centre 

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and mysterious structure better than ever before

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Hubblecast is produced by ESA/Hubble at the European Southern Observatory in Germany

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The Hubble mision is a project of international cooperation between NASA and the European Space Agency

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www.spacetelescope.org

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Transcribed by ESA/Hubble. Translation ––