galaxies

It’s back and it’s better than ever

No it’s not the return of Red Dwarf to our TV screens*, it’s the new Galaxy Zoo that has got the blogosphere (and indeed the TV) buzzing. To refresh your memory, Galaxy Zoo is the online citizen science project, headed by Dr Chris Lintott, that gives members of the public the chance to help do real science in classifying literally thousands of galaxies from the Sloan Digital Sky Survey.

This morning the GZ team launched the follow-up (Galaxy Zoo 2), which will study a quarter of a million galaxies to “search for the strange and unusual.” This evening I had a go at the new classifying routine and interface and quickly remembered how addictive the site is. So why not head on over and have a go — as the team say “even five minutes’ work will provide a valuable contribution.” And if you’re sceptical that this isn’t a real zoo (as it doesn’t appear to have any animals), well…you just have to look very carefully!

(*although that is very cool)

A Milky Way metro?

milkywaymetroArtist’s impression of the Milky Way Credit: NASA/JPL-Caltech

When I started my degree in London years ago one of the first things I had to get to grips with was navigating the Tube. Fortunately it took no time at all, thanks to the world famous tube map, originally designed by Harry Beck in the 1930s. Its ingenious design simplifies the mish-mash of routes across London into an easy to read diagram, allowing the reader to work out how to get where they want to go, easily. It’s with this in mind that Harvard computational sociologist Samuel Arbesman has come up with the “Milky Way Transit Authority” map. It’s a tube map style diagram of our home in the Cosmos — the Milky Way. Replete with all the must see stops in the Galaxy (the Orion nebula stop isn’t finished yet and there’s a really strong wind whistling through the P Cygni station) the map neatly shows our place in space. You can download it as a .pdf on Samuel’s webpage (.pdf link here), but be warned; with news like this cropping up every now and then, a journey on the ‘Orion line’ might take a bit longer than expected!

Hat tip: J V Chamaray of BBC Focus magazine

Super sharp Hubble shows stars in nearby galaxies

The Hubble Space Telescope is renowned for its incredible resolution used in studying the depths of the Universe – from the earliest galaxies to some of the grandest spirals. Recently though it has been using these superb capabilities to observe nearby galaxies – that is, a selection of galaxies between about 7 and 13 million light years from the Earth.

Above: Hubble’s resolution has revealed NGC 253 as a swirl of countless stars and dust lanes, enabling new insights into the character and structure of this beautiful galaxy.

At this time of year I love to get out a wide-field refracting telescope and use it to spot the relatively bright galaxies M31 (the Andromeda Galaxy) and M33. Through the eyepiece they appear as bright smudges of light, M31 being slightly elongated in shape. Those smudges are in fact the accumulated light of billions of stars shining away brightly, inside their respective galaxies. Yet we can’t see the individual stars in the galaxy with our amateur telescopes because their resolving power is simply too low, they appear blurred and merged together. But with Hubble things are much different.

When it looked at 69 nearby galaxies, its powerful optics were able to show individual stars and glittering star clusters within them. This ability to look at the fine detail has allowed astronomers to make important studies into the lives of these stars, how they are born and more. Astronomers can then also use the observations to make detailed conclusions about the shape and structure of the (often intricate) galaxy they are studying.

We can liken some of the previous observations to trying to understand how the population of a city lives, interacts and moves around, just by looking at a street-map. With Hubble’s brilliant resolution astronomers have been able to get a far more detailed view of the lives of galaxies and their stars – we can study the people in the street as it were. As Benjamin Williams, of the University of Washington says in the ESA press release “With these images, we can see what makes each galaxy unique”.

Left: A maelstrom of thousands upon thousands of individual stars reveals itself in this Hubble Advanced Camera for Surveys image of NGC 300, some 7 million light years away from Earth.

These observations are important because it is essential for astronomers to build an understanding of galaxies close to the Milky Way, in order to investigate (and hopefully understand) those which might be subtly different in the farther, or even extremely distant Universe. How are stars forming and how fast? Where are the old stars and why are some galaxies so massive? These are all questions which studies like these look to answer. Thankfully the survey which Hubble was working on (the ANGST or ACS Nearby Galaxy Survey Treasury) is wide ranging and shows a diverse sample of galaxies. It aims to create a practically complete study of all the galaxies in what is known as the Local Neighbourhood. So slowly but surely we are getting to know our cosmic neighbours!

Meanwhile, with the Hubble Servicing Mission 4 postponed until further notice (due to an anomaly with Hubble’s control unit) we are going to have to sit back and wait patiently to see if, and when, Hubble can get back to doing its usual spectacular science.

Image credits – Top; NASA, ESA, J. Dalcanton and B. Williams (University of Washington), T.A. Rector/University of Alaska Anchorage, T. Abbott and NOAO/AURA/NSF: Left hand side; NASA, ESA, J. Dalcanton and B. Williams (University of Washington)

A prodigious pinwheel shines in the darkness

The stunning galaxy M83. Credit: ESO

My first press release for the European Southern Observatory has now been released. It accompanies what is, of course, the real interest in the story – a fantastic new image from the observatory’s Wild Field Imager camera. It shows the stunning spiral galaxy M83, arguably one of the most beautiful galaxies in Messier’s famous catalogue of deep sky objects. Here’s a snippet from the press release:

This dramatic image of the galaxy Messier 83 was captured by the Wide Field Imager at ESO’s La Silla Observatory, located high in the dry desert mountains of the Chilean Atacama Desert. Messier 83 lies roughly 15 million light-years away towards the huge southern constellation of Hydra (the sea serpent). It stretches over 40 000 light-years, making it roughly 2.5 times smaller than our own Milky Way. However, in some respects, Messier 83 is quite similar to our own galaxy. Both the Milky Way and Messier 83 possess a bar across their galactic nucleus, the dense spherical conglomeration of stars seen at the centre of the galaxies.

You can read the full press release and download a hugggeeee version of the image here.

Hubble’s magnificent mergers


OK I admit it. Galaxies are my favourite objects that the Hubble Space Telescope studies and images. But it’s true; there’s something so awesome about the HST images that ooze detail in a way that captures the vast and magnificent nature of these ‘stellar cities’. But it’s not all about the pictures. Hubble has allowed scientists to see the farthest galaxies in the Universe, that also happen to be some of the earliest too. Those observations have given us a real insight into how the galaxies we see today form. Hubble has studied Cepheid variables in distant galaxies too, allowing us to make accurate distance measurements of far off galaxies.

Today the Hubble team have released the most stunning collection of galaxy images I have ever seen. Fifty nine images in total showing many galaxies merging. What’s fascinating is that you can piece together a rough idea of how a merger takes place, out of several images of different ‘collisions’. This isn’t unusual. Astronomers do it all the time. If you wanted to see the lifetime of a Sun-like star you obviously wouldn’t hang around for 10 billion years to watch it from start to finish. What you do is look around the Universe for different Sun-like stars at different points in their life. We can do this now to get at a very basic overview of how a galaxy merger unfolds.


The above image is made from six separate images of differing collisions. Yet put together they show the progression of a galaxy merger. In reality a galaxy collision is a slow and stately affair. In fact during galaxy mergers the stars within the galaxy generally don’t smash together. That’s because of the vast distances between stars; however some stars will ultimately be thrown from the galaxies out into the depths of space.


Over millions of years the gravity of the galaxies begins to twist and shape streams of stars. In the first panel you can see the left hand galaxy is slowly starting to deform as the two galaxies begin to interact. Emerging from the lower left of the left galaxy is a noticeable stream of stars – the first sign that a merger is underway. In the second panel the merger is further along. Here much bigger streams, called ‘tidal tails’, extend out from the galaxies as the two get ever closer. In the third panel the merger is advanced even more with a massive bridge of millions of stars stretching between the two galaxies’ cores. In the last three images the mergers show dramatic twisting and swirling shapes. As the collisions of clouds of dust and gas take place, shockwaves travel through the galaxies. This results in a staggering burst of star formation (note the young blueish stars in the fourth image). Eventually the two galaxies will become one – usually a enormous dusty elliptical galaxy.

To see the full catalogue of the Hubble merger images view the press release here and of course you can watch the latest episode of the Hubblecast about the images here.

First image credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and K. Noll (STScI). Second image credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University), K. Noll (STScI), and J. Westphal (Caltech). Third image credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)

NAM news 2: Massive starburst in the early Universe

Dr. Scott Chapman from the Institute of Astronomy in Cambridge has just presented the latest results from a collaboration between the MERLIN UK radio telescope array, Keck (at optical wavelengths), the VLA in the US and the Plateau de Bure submillimetre observatory in France. The results show that there was a group of galaxies in the early Universe that experienced an incredible burst of star formation about 2 billion years after the Big Bang. This phenomenal burst of activity was observed in galaxies that were shining a mere 3 billion years after the Big Bang and is thought to have been vastly more dramatic than any star formation we see nowadays.

Remarkably it was only until relatively recently that astronomers detected a similar gathering of sub-mm galaxies in the early Universe. These galaxies are particularly faint in optical wavelengths but very bright in the radio wavelengths. Instruments like SCUBA mounted on the James Clerk Maxwell Telescope (JCMT), on Mauna Kea in Hawaii could see the sky in sub-mm wavelengths and so could detect them; allowing astronomers to investigate their nature. Yet astronomers believed that these galaxies were only part of what was going on (star-forming wise) in the early Universe, because SCUBA was good at looking at relatively cooler sub-mm galaxies.

Now, these new results from the collaboration of many telescopes do indeed show a gathering of slightly warmer galaxies, not altogether different from those spied by SCUBA, undergoing dramatic star formation. The observations indicate that these galaxies are surrounded by vast clouds of gas. That gas, the astronomers argue, will keep the star formation going at a tremendous rate for “hundreds of millions of years”.

You can see images from the results and a very cool video here.

“A grand design in a galactic festoon”

The latest Hubblecast is now out! In this episode we present a new stunning Hubble image. M74 is a beautiful spiral galaxy located 32 million light years away. Hubble imaged the galaxy with its Advanced Camera for Surveys between 2003 and 2005.

“Messier 74, also called NGC 628, is a stunning example of a ‘grand-design’ spiral galaxy that is viewed by Earth observers nearly face-on. Its perfectly symmetrical spiral arms emanate from the central nucleus and are dotted with clusters of young blue stars. In the new Hubble image we can also see a smattering of bright pink regions decorating the spiral arms.

These are huge, relatively short-lived, clouds of hydrogen gas which glow due to the strong radiation from hot, young stars embedded within them; glowing pink regions of ionized hydrogen (hydrogen that has lost its electrons).”
You can watch the Hubblecast here.

Image credit: NASA, ESA and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration