Today, I want to talk about something a bit unusual that was discovered.
It's called Hanny's Voorwerp.
I may be pronouncing that wrong? [MV: it's pronounced quite well]
This object was discovered by accident,
as are many of the most exciting astronomical discoveries.
It was discovered by a member of the public,
a schoolteacher in Holland, named Hanny van Arkel.
The name is Hanny's Voorwerp, and voorwerp is Dutch for object.
So this is Hanny's object, and that's what it looks like. A funny-looking thing.
One of the basic things we do as astronomers is take pictures.
Even now we have digital pictures from big telescopes
we still get a lot of information by looking at them with our eyes.
The typical thing for an astronomer like myself to do,
would be to cycle through thousands of images of objects.
This is for my own survey, these are images from the Hubble space telescope,
it's a galaxy, a disc like the Milky-way, but we see it edge-on.
And we see a huge variety of objects.
Round ones, some with spiral arms, a 'train wreck',
a collision of two different galaxies.
Even though we have automated routines to gather information,
we can teach a computer to do this,
those automated routines are not perfect.
There's still a lot to gain from using our eye-brain system,
which is really good at picking out patterns or features.
In my own research I may have gone through 5,000 of these images.
Recording whether they have spiral arms, are round,
whether they have bars, whether they're all messed up.
Together with about eight other people,
we could cover six or seven thousand galaxies,
with each one being done a couple of times.
When you have a survey like the Sloan digital sky survey,
we have millions of galaxies.
That's far too many for one individual to look though one by one.
So in this case the Galaxy Zoo project has enlisted members of the public to help.
The Galaxy Zoo is a project I'm not involved with,
but it's close to our hearts here at Nottingham,
because colleague Steven Bamford plays a key role.
They've enlisted hundreds of thousands of people.
Members of the public, schoolchildren, amateur astronomers, etc.
- And me! - and Brady of course to help with this project.
How many galaxies have you looked at? - I did about twenty
- I don't think you're up there in the top...
This is the galaxy zoo webpage at galaxyzoo.org
After a galaxy zoo member logs in, they do the same thing,
they are presented with pictures of galaxies and they look at them
they're asked very specific questions about the galaxy.
All those classifications are combined in a statistical way
and the project has shown that this is as robust as when done by professional astronomers.
In the first leg of the project they had about 150,000 people
classifying a million galaxies submitting 15 million classifications.
You get a real hands-on connection with the science.
The images themselves are beautiful,
you're looking as spectacular pictures of galaxies,
collections of hundreds of billions of stars, billions lightyears away.
And there's always the possibility that you uncover that nobody else has.
That's exactly what happened with Hanny's Voorwerp.
Hanny van Arkel, schoolteacher from Holland,
a participant in Galaxy Zoo,
and she uncovered this strange object.
She asked on the forum if anyone else knew what it was.
No one could explain it, and it became an object of interest.
It was out of the ordinary and unexpected.
And that's always what we like follow-up.
What you're seeing here is lots of galaxies,
there's this big galaxy here with spiral arms,
there's a companion galaxy next to it,
but what we're interested in this green object here, Hanny's Voorwerp.
It is irregularly shaped, so something is strange,
and in this colour scheme it's bright green.
It is very different in colour from the galaxies around it.
That means it emits light at a particular narrow frequency.
This was a puzzle, it wasn't immediately obvious what it was.
Members of galaxy zoo and astronomers have followed it up,
with many telescopes at different wavelengths,
trying to find out as much as they could.
They've determined it doesn't have any stars of it's own,
it's mostly gas and dust,
it's the remnants of a tiny galaxy that has been pulled apart,
by the gravity of this much larger galaxy.
We might not normally see that,
because without stars it wouldn't be very bright.
What they think has happened, is that something
has dumped a lot of energy in this gas.
It's ionized it, which makes it glow at this wavelength.
That object could be something like a quasar,
a massive black hole accreting mass and spewing out energy,
but there's no smoking gun in this picture.
At any wavelengths, they can't see the candidate quasar.
It may be hidden in the center of this galaxy here.
But another intriguing possibility is that
it was spewing out energy but stopped.
We've had enough time for the energy to reach Hanny's Voorwerp,
ionize that gas and make it glow.
That gap could be as long as 100,000 years.
What could be seen here is a light echo of a dormant quasar.
And we can still see what kind of effect it had.
transcription: merijn.vogel@gmail.com