- Galaxy Zoo is a
project
project
How many arms does a spiral galaxy have? Can you spot a galaxy with a 'peanut' bulge? Or how about a galactic merger? Answers to these and other strange questions will be provided by ordinary web users who, by working together, have proven to be just as good at galaxy-spotting as professional astronomers.
The new initiative is a follow-up to the highly successful Galaxy Zoo project that enabled members of the public to take part in astronomy research online. But whereas the original site only asked members of the public to say whether a galaxy was spiral or elliptical, and which way it was rotating, Galaxy Zoo 2 asks them to delve deeper into 250,000 of the brightest and best galaxies to search for the strange and unusual.
The Galaxy Zoo 2 website is launched on 17 February at www.galaxyzoo.org.
'The first Galaxy Zoo provided us with a Rough Guide to the sky and now we want our users to fill in all the details and create a real Hitchhiker's Guide to the Galaxies,' said Dr Chris Lintott of Oxford University, one of the founders of Galaxy Zoo.
Astronomers came up with the idea of getting online volunteers involved because the human brain is still better at doing pattern recognition tasks than a computer. What they had not expected was the huge enthusiasm for the project; in the last 18 months 80 million classifications of galaxies were submitted on one million objects at www.galaxyzoo.org by more than 150,000 armchair astronomers from all over the world.
Dr Kevin Schawinski of Yale University, another of Galaxy Zoo's founders said: 'The response from the public was absolutely overwhelming and, with their help, we've been able to learn a lot about how galaxies evolve and how they relate to their environment. With the detail from Zoo 2, we'll be able to discover even more about how galaxies work.'
'Galaxy Zoo has given everyone with a computer an opportunity to contribute to real scientific research. We want people to feel truly involved in the project and keep them up to date with what we're doing and with the results they're generating,' said Dr Steven Bamford of the University of Nottingham.
As with the original site people are free to look at and describe as many galaxies as they like – even five minutes' work will provide a valuable contribution. Galaxy Zoo 2 is intended to be even more fun as galaxies are pitted against each other in 'Galaxy Wars' (which one is more spirally?) and users can compete against their friends to describe more objects as well as record their best finds.
Proof that unusual discoveries can be made is the catalogue of merging galaxies provided by users – more than 3000 of these rare cosmic pile-ups have been caught in the act by Galaxy Zoo volunteers. The team have already used the IRAM radio telescope in Spain's Sierra Nevada to follow up the most exciting mergers, and are asking for more examples to study.
'In this International Year of Astronomy, it's great to have so many people looking at these beautiful image of galaxies from the Sloan Digital Sky Survey,' said Professor Bob Nichol of the University of Portsmouth, a member of the original Galaxy Zoo team. 'No single professional astronomer has ever looked at all these images and sometimes astronomers miss the wonder of what they are. I think the public get this better than us.'
For more information visit www.galaxyzoo.org or contact Dr Chris Lintott of Oxford University on +44 (0)1865 273638; mobile: +44 (0)7808 167288) or email cjl@astro.ox.ac.uk
Alternatively, contact the University of Oxford Press Office on +44 (0)1865 283877 or email press.office@admin.ox.ac.ukOr Dr Steven Bamford of the University of Nottingham on +44 (0)115 846 8815; mobile +44 (0)7812 028021 or email steven.bamford@nottingham.ac.uk
Or Professor Bob Nichol of the University of Portsmouth on +44 (0)23 9284 3117; mobile : +44 (0)7963792049 or email bob.nichol@port.ac.uk
USA CONTACTS: Dr Kevin Schawinski of Yale University on +1 203 432-9759 or email kevin.schawinski@yale.edu or Suzanne Taylor-Muzzin at the Yale office of public affairs; +1 203 432 8555 or suzanne.taylormuzzin@yale.edu
The Galaxy Zoo team is led by scientists from the University of Oxford, the University of Nottingham, the University of Portsmouth, Johns Hopkins University (USA), UC Berkley (USA), Penn State (USA), Adler Planetarium, Chicago (USA) and Yale (USA), and Fingerprint Digital Media of Belfast. The development of Galaxy Zoo 2 was funded by The Leverhulme Trust, and a grant from Microsoft.
The new digital images used in Galaxy Zoo were taken using the Sloan Digital Sky Survey telescope in New Mexico. For more on the Sloan Digital Sky Survey visit www.sdss.org. For full details of those involved go to www.sdss.org/collaboration/credits.html
Astronomers in two UK-led international collaborations have separately uncovered a type of galaxy that represents a missing link in our understanding of galaxy evolution. Galaxy Zoo, which uses volunteers from the general public to classify galaxies and the Space Telescope A901/902 Galaxy Evolution Survey (STAGES) projects have used their vast datasets to disentangle the roles of "nature" and "nurture" in changing galaxies from one variety to another.
Both studies have identified a population of unusual red spiral galaxies that are setting out on the road to retirement after a lifetime of forming stars. Crucially, nature and nurture appear to play a role in this transformation: both the mass of a galaxy as well as its local environment are important in determining when and how quickly its star formation is shut down. The scientists' work appears together in a forthcoming edition of Monthly Notices of the Royal Astronomical Society.
Astronomers place most normal galaxies into two camps according to their visual appearance: either disk-like systems like our own Milky Way, or round, rugby-ball shaped collections of stars known as ellipticals. In most cases, a galaxy's shape matches its colour: spiral galaxies appear blue because they are still vigorously forming hot young stars. Elliptical galaxies, on the other hand, are mostly old, dead, and red, and tend to cluster together in crowded regions of space.
The Galaxy Zoo team examined the connection between the shapes and colours of over one million galaxies using images from the largest ever survey of the local Universe, the Sloan Digital Sky Survey and the help of hundreds of thousands of volunteers from the general public. A key ingredient to their success was reliably classifying the appearance of galaxies by actually looking at them, rather than relying on error-prone computer measurements.
Surprisingly, they find that many of the red galaxies in crowded regions are actually spiral galaxies, bucking the trend for red galaxies to be elliptical in shape. These red spiral galaxies may be just the smoking gun astronomers have been looking for.
Dr. Steven Bamford, an STFC postdoctoral researcher at the University of Nottingham, led the Galaxy Zoo study. "In order to have spiral arms, they must have been normal, blue, spiral galaxies up until fairly recently. But for some reason their star formation has been stopped, and they have turned red. Whatever caused them to stop forming stars can't have been particularly violent, or it would have destroyed the delicate spiral pattern." The Galaxy Zoo team concludes that a more subtle process must be at work, one that kills off star formation but does not disrupt the overall shape of the galaxy.
While Galaxy Zoo looked at the gross properties of millions of galaxies across a large chunk of sky, the STAGES project took a complementary approach by examining in detail just the sort of neighbourhoods where these transformations are expected to occur. Dr. Christian Wolf, an STFC Advanced Research Fellow at the University of Oxford, trained the Hubble Space Telescope on a region of space crowded with galaxies known as the A901/902 supercluster. Like the Galaxy Zoo team, Dr. Wolf also uncovered a surprisingly large population of spiral galaxies in the supercluster that are red in colour.
So has the star formation in these red spiral galaxies been completely killed off? The answer is no: despite their colour, the red spirals are actually hiding star formation behind a shroud of dust. Invisible to our (or Hubble's) eye, this star formation is only detectable in the infrared part of the spectrum i.e. radiation emitted from the galaxies at wavelengths longer than visible light.
Dr. Wolf remarks, "For the STAGES galaxies, the Spitzer Space Telescope provided us with additional images at infrared wavelengths. With them, we were able to go further and peer through the dust to find the missing piece of the puzzle". Within the supercluster, Dr. Wolf discovered that the red spirals were hiding low levels of hidden star formation, despite their otherwise lifeless appearance in visible light.
Putting the observations from both projects together, the picture that emerges is a gentle one: the star formation in blue spiral galaxies is gradually shut off and hidden behind dust, before petering out to form smooth "lenticular" (lens-shaped) red galaxies with no trace of spiral arms. To go further and transform the galaxy into an elliptical would require more violent mechanisms, such as the wholesale collision of galaxies.
Location is key: the red spirals are found primarily on the outskirts of crowded regions of space where galaxies cluster together. As a blue galaxy is drawn in by gravity from the rural regions to the suburbs, an interaction with its environment causes a slow-down in star formation. The closer in a galaxy is, the more it is affected.
But if environment decides where the process occurs, the mass of the galaxy decides how quickly it takes place. Because both STAGES and Galaxy Zoo looked at such large numbers of galaxies, they were able to further subdivide them according to how much they weighed. Sure enough, both groups find that galaxy mass is also important. Professor Bob Nichol of Portsmouth University, a Galaxy Zoo team member, explains: "Just as a heavyweight fighter can withstand a blow that would bring a normal person to his knees; a big galaxy is more resistant to being messed around by its local environment. Therefore, the red spirals that we see tend to be the larger galaxies - presumably because the smaller ones are transformed more quickly."
Chris Lintott, Galaxy Zoo team leader at the University of Oxford, pays tribute to the role of the general public in the Galaxy Zoo research. "These results are possible thanks to a major scientific contribution from our many volunteer armchair astronomers. No group of professionals could have classified this many galaxies alone."
Meghan Gray, STFC Advanced Fellow at the University of Nottingham and leader of the STAGES survey, comments on the agreement of the two projects on the role of environment and mass: "Our two projects have approached the problem from very different directions, and it is gratifying to see that we each provide independent pieces of the puzzle pointing to the same conclusion."
The next step for both teams is to find out exactly what shuts off the star formation, by looking inside the galaxies themselves. One suspect behind the slow demise of galaxies is a process known as strangulation, in which a galaxy's fuel supply is stripped away as it encounters the crowd. Starved of the raw material needed to form new stars, it will slowly change colour from blue to red as its existing stars age.
The STAGES team's findings on the properties of red spiral galaxies will
appear online on November 25 2008 at http://arxiv.org/list/astro-ph/new.
The Galaxy Zoo results are available online at http://arxiv.org/abs/0805.2612.
A composite of images from the two surveys (click for high resolution version):
These images of three galaxies from the Galaxy Zoo (top) and STAGES surveys (bottom) show examples of how the newly discovered population of red spiral galaxies on the outskirts of crowded regions in the Universe may be a missing link in our understanding of galaxy evolution.
At left, both surveys find examples of normal spiral galaxies displaying all the hallmarks of youth: blue in colour, they are disk-like in structure. The obvious spiral arms host knotty structures where large numbers of hot young stars are being born.
On the right are examples of typical rounded balls of stars known as elliptical galaxies. The reddish colour indicates that their stars are mostly old. With no gas left to use as fuel to form any more, they are old, dead and red
In the centre are examples of the new "red spiral" galaxy found in large numbers by both the STAGES and Galaxy Zoo collaborations. While still disk-like and recognizably spiral in shape, their spiral arms are smoother. Furthermore, their colour is as red as the ellipticals. Astronomers from both teams believe these red spirals are objects in transition, where star formation has been shut off by interactions with the environment.
STAGES image credit: Marco Barden, Christian Wolf, Meghan Gray, the
STAGES survey
STAGES image from Hubble Space Telescope, colour from COMBO-17 survey
Galaxy Zoo image credit: Sloan Digital Sky Survey
Galaxy Zoo harnessed the power of the thousands of volunteers from the general public to classify the shapes of over one million galaxies. It used images from the Sloan Digital Sky Survey, the largest ever survey of the local Universe, covering one quarter of the sky.
Galaxy Zoo webpage http://www.galaxyzoo.org
The Space Telescope A901/902 Galaxy Evolution Survey (STAGES) project observed the A901/902 supercluster with the Hubble (visible) and Spitzer (infrared) Space Telescopes. The supercluster is composed of over one thousand galaxies, located 2.6 billion light-years away.
STAGES webpage http://www.nottingham.ac.uk/astronomy/STAGES
Armchair astronomers using the galaxyzoo.org website have identified over 500 overlapping galaxies in the local Universe when astronomers had previously only known of 20 such systems.
"This is the best Christmas present our users could hope for!" said Dr Chris Lintott of Oxford University, a member of the galaxyzoo.org team. "Overlapping galaxies are useful because they enable us to study the dust in each system. Dust grains play a crucial role in the evolution of galaxies and how we see them - the presence of such dust is critical for star formation."
Visitors to galaxyzoo.org get to see stunning images of galaxies. By classifying some of these images visitors are helping astronomers to understand the structure of the universe. The new digital images were taken using the robotic Sloan Digital Sky Survey telescope in New Mexico.
Each of the 500+ overlapping galaxies was discovered by a member of the public signed up to the galaxyzoo.org forum where armchair astronomers can compare notes on the images of galaxies they have seen and classified using the website. The search for overlapping galaxies was led by Bill Keel of the University of Alabama who wrote on the forum asking people to look out for suitable systems.
Astronomers have been awarded five night's use of the WIYN telescope on Kitt Peak, Arizona, to take a closer look at the overlapping galaxies identified by the Galaxy Zoo volunteers. The WIYN telescope is one of the largest in the Northern hemisphere and one of the most advanced in the world. This work will begin on 25 April 2008.
"We are expecting to get some spectacular images from our Arizona nights but, with the first set of science papers on Galaxy Zoo coming out very soon, we still need more volunteers to visit galaxyzoo.org" said Dr Chris Lintott. "Even if you've visited the site before, please come back and classify some more galaxies in between mouthfuls of turkey and Christmas pudding as we need your help to confirm our results, results which could have a profound impact on our models of the universe."
The Galaxy Zoo welcomes a flood of visitors. A new scientific project, called the Galaxy Zoo, is celebrating the enrollment of its first 85,000 participants, exploring the distant Universe via the Internet.
The goal of the project is to classify images of one million galaxies from the Sloan Digital Sky Survey (SDSS-II), with the help of the general public.
The Galaxy Zoo opened its online gates in mid-July. "The response has been breathtaking," said Alex Szalay from Johns Hopkins University, a member of the Galaxy Zoo team. "The traffic was 20 times higher than what we hoped for. This shows the public is really interested in science if they feel they can contribute in a meaningful way."
"Galaxies come in two main categories," explained team member Daniel
Thomas of Portsmouth University. "In spiral galaxies, like the Milky Way, most
stars follow circular orbits and move in the same direction, giving the galaxy a
flattened, frisbee-like shape. In elliptical galaxies, on the other hand, stars
move on randomly oriented, elongated paths, so the galaxy as a whole has a football-like
shape. "
Visitors to the Galaxy Zoo take a short online tutorial then sort galaxy images into these categories. "Computers can do this classification automatically,
but humans are far more accurate," said Thomas. "It's like trying to
distinguish male and female faces -- no computer algorithm will do this as accurately
as a person, because we are much better at identifying the most important cues."
But giving individual attention to a million galaxies takes many pairs of eyes, especially as every galaxy must be classified by multiple people to ensure reliability.
Working around the clock, the Galaxy Zoo team made its website fast enough for the flood of participants, explained a tired Jan Vandenberg of Johns Hopkins. "The demand on the first day was so great, we blew a circuit breaker in our computer room!"
The team upgraded their computer hardware, simply to keep ahead of public demand.
According to Szalay and Vandenberg, Galaxy Zoo users have already submitted over
12 million galaxy classifications. At its peak, the Galaxy Zoo served up more than
60,000 galaxies an hour to users around the globe.
"We now have the world's largest computer working for us, through the combined power of all these human brains," commented Thomas.
"We wanted to create an intriguing yet intuitive web site," said Galaxy Zoo site designer Phil Murray, "so that anyone, from around the globe, would enjoy coming back time and time again to take part. It helps that the galaxies themselves are such beautiful and evocative objects."
As with any zoo, the oddest animals provide much of the fun. The Galaxy Zoo team has received thousands of emails from those who want to share their latest discovery. "It's very rewarding to hear from someone who has found a particularly beautiful image, or has a question about a set of merging galaxies they've observed," said Chris Lintott from the University of Oxford. "We've had complaints that the site is addictive, as you never quite know what the next image is going to reveal!"
"We want our catalogue to be the most accurate, as well as the largest," explained Oxford astronomer Anze Slosar. "To do that we need to have several people classify each galaxy. There's plenty out there for everyone, and the next galaxy is always difficult to resist."
The underlying science goal, explained Slozar, is to understand how spiral and elliptical galaxies form. "We have theories for how this happens, but to test them we need to know what kinds of galaxies are found in different cosmic environments. The combination of SDSS-II and the Galaxy Zoo will give just the information we need."
Already hard at work analyzing their data, the team hopes to welcome more visitors through the gates of the world's newest - and most unusual - zoo.
The Galaxy Zoo is open for business at www.galaxyzoo.org.
The Sloan Digital Sky Survey (SDSS-II) is the most ambitious astronomical survey ever undertaken. When completed, it will provide detailed optical images covering more than a quarter of the sky, and a 3-dimensional map of millions of galaxies and quasars. The data are released to the scientific community and the general public in annual increments
Funding for the SDSS-II has been provided by the Alfred P. Sloan Foundation, the National Science Foundation, the U.S. Department of Energy, the Japanese Monbukagakusho, the Max Planck Society and the Higher Education Funding Council for England.
The SDSS is managed by the Astrophysical Research Consortium for the Participating
Institutions: the American Museum of Natural History, Astrophysical Institute Potsdam,
University of Basel, Cambridge University, Case Western Reserve University,
University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study,
the Japan Participation Group, The Johns Hopkins University, the Joint Institute
for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology,
the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos
National Laboratory, the Max-Planck-Institute for Astronomy (MPA), the Max-Planck-Institute
for Astrophysics (MPIA), New Mexico State University, Ohio State University, University
of Pittsburgh, University of Portsmouth, Princeton University, the United States
Naval Observatory, and the University of Washington.
Everyone can visit the ‘Galaxy Zoo’
Astronomers are inviting members of the public to help them make major new discoveries by taking part in a census of one million galaxies.
Visitors to www.galaxyzoo.org will get to see stunning images of galaxies, most of which have never been viewed by human eyes before. By sorting these images into “spiral galaxies” (like our own Milky Way) or “elliptical galaxies”, visitors will help astronomers to understand the structure of the universe. The new digital images were taken using the robotic Sloan Digital Sky Survey telescope in New Mexico.
‘It’s not just for fun’ said Kevin Schawinski of Astrophysics at Oxford University where the data will be analysed. ‘The human brain is actually better than a computer at pattern recognition tasks like this. Whether you spend five minutes, fifteen minutes or five hours using the site your contribution will be invaluable.’ Visitors will be able to print out posters of the galaxies they have explored and even compete to see who’s the best virtual astronomer.
The galaxyzoo.org team were inspired by projects such as Stardust@home, in which NASA invited the public to sort through dust grains obtained by a mission to Comet Wild-2. Oxford’s Dr Chris Lintott, co-presenter of the BBC’s Sky at Night programme and galaxyzoo.org team member, commented: ‘What the Stardust team achieved was incredible, but our galaxies are much more interesting to look at than their dust grains. We hope that participants in Galaxy Zoo will not only contribute to science, but have a lot of fun along the way.’
Images for the project are taken from the Sloan Digital Sky Survey, which uses a 142-megapixel digital camera to create the largest digital map of the universe. ‘It is great that digital archives we have built for science are now being used by the public to look at the universe’ says Professor Bob Nichol from the University of Portsmouth. ‘It will be great to have all the galaxies classified; it’s as fundamental as knowing if a human is male or female.’
The astronomers hope that the survey will shed light on how different kinds of galaxies are distributed across the sky. The results might even reveal that there is something fundamentally wrong with existing models of the universe.
Sir Patrick Moore, an enthusiastic supporter of the project, said: ‘Non-professionals have always been deeply involved in studying the sky and they now have yet another opportunity to make themselves really useful. Moreover, their help is now of immense value so do join up – as I am doing myself!’