The NASA/ESA Hubble Space Telescope
with a little help from an amateur astronomer
has produced one of the best views yet of nearby galaxy Messier 106
a striking spiral galaxy with a number of secrets
Hubblecast episode 62: A spiral galaxy with a secret
Located a little over 20 million light-years away
practically a neighbour by cosmic standards
Messier 106 is one of the brightest and nearest spiral galaxies to our Milky Way
Although it may not look particularly unique
some of its features have baffled astronomers for years
Messier 106 has a supermassive black hole at its centre
Although this is true for most galaxies
this black hole is particularly active and hungry
gobbling up nearby material at a startling rate
This huge black hole’s bottomless appetite
is behind much of the galaxy’s unusual behaviour
Messier 106 appears to be emitting powerful radiation from its centre
something we do not see with our Milky Way
This is caused by the very active black hole at the galaxy’s centre
which violently drags gas and dust inwards
This material heats up, emitting microwave and X-ray radiation as it does so
However, this emission is not the most intriguing feature of this spiral galaxy
This image shows the galaxy’s other not-so-hidden secret:
alongside its two regular star-packed spiral arms
it appears to have two more, made out of hot, glowing gas
While these ghostly extra arms have been known about for decades
astronomers were unsure of how they formed — until recently
Yet again, the culprit is Messier 106’s supermassive black hole
The extra arms are actually regions of gas
that have been heated up to scorching temperatures of millions of degrees
As material spins around and heats up at the galaxy’s centre
the turbulent motion causes jets of material to shoot outwards
The jets disrupt and heat up all the gas in their path
which in turn excites denser gas towards the centre of the galaxy
This gas is tightly bound together, so it remains roughly straight
However, the looser gas further out is blown away from the jets
so that it curves out of the galactic plane
creating the arching red arms seen in this image
These “extra” arms are very unusual, and this poses a bit of a puzzle
because galactic jets are actually quite common
It is not just spirals that show jets
elliptical galaxies do too, such as the spectacular radio jets seen
around the nearby galaxies Hercules A and Centaurus A
And yet none of these show any of the features seen in Messier 106
Some of the data for this image of Messier 106 were provided
by amateur astronomer Robert Gendler
Together with Hubble, these data allow us to visualise the galaxy’s chaotic centre
and mysterious structure better than ever before
Hubblecast is produced by ESA/Hubble at the European Southern Observatory in Germany
The Hubble mision is a project of international cooperation between NASA and the European Space Agency
www.spacetelescope.org
Transcribed by ESA/Hubble. Translation ––