2 Year Anniversary Poster

MWP Poster Extract

It’s been two years since everyone began helping the Milky Way Project map bubbles in our galaxy (and other things too). To celebrate we’ve created another anniversary poster, featuring the names of all the participants. You can download it here (warning that’s a 19MB file) or a slightly smaller one here (5MB).

The Milky Way Project is now producing science – with two papers already published and online. You can see these and all the Zooniverse publications at http://zooniverse.org/publications. We have some new features coming to the site soon – so stay tuned.

The Andromeda Project

Almost two years ago we launched the Milky Way Project and the search for bubbles in our galaxy continues at http://www.milkywayprpject.org. Today we’re pleased to to welcome a new space-based Zooniverse project into the family. The Andromeda Project (http://www.andromedaproject.org) is science in the galaxy next-door and we thought that the MWP community might like this new project. It’s very much our new sister site. We’re betting that you can help us explore some amazing Hubble Space Telescope data, to help identifying star clusters in Andromeda.

The Andromeda Project

There may be as many as 2,500 star clusters hiding in Hubble’s Andromeda images, but only 600 have been identified so far in months of searching, and star clusters tend to elude pattern-recognition software. We know it’s something that everyone can help with, even without extensive training. There are more than 10,000 images waiting at http://www.andromedaproject.org – they all come from the Panchromatic Hubble Andromeda Treasury, or PHAT for short. The goal of the PHAT survey is to map about one-third of Andromeda’s star-forming disk, through six filters spread across the electromagnetic spectrum — two ultraviolet, two visible and two infrared.
The Hubble telescope started gathering images for the treasury in 2010 and is expected to send its last batch of images back to Earth in the summer of 2013. The Andromeda Project aims to produce the largest catalog of star clusters known in any spiral galaxy.

You can also find our the Andromeda Project on Twitter @andromedaproj and on Facebook too.

Milky Way Project on German TV

Some months ago I was contacted by the producers of a well known German science programme called Nano, which is broadcast on channel ZDF. They were recording a segment for the show on citizen science, and were keen to talk to me about the Milky Way Project. I was happy to help, they visited, we chatted, I walked up and down corridors and through doors, they filmed, and went on their way. The item was finally shown on Nano last week, on 7 September, and they did a great job showcasing our amazing images. You can watch the video for a couple more days here, and an accompanying article can be found on this webpage – these all in German. And yes, that’s me, at my desk in Heidelberg.

Milky Way Project is just one of the projects featured on the programme. I particularly like Artigo, one of the other projects featured. The aim of Artigo is to tag images of artworks, to enable catalogues of artwork to become more searchable. Artigo is set up like a game: two users are simultaneously shown the same image, and they’re asked to type in words that describe an aspect of the work they’re looking at. The users then score points based on the tags they enter: 0 points for a tag that’s never been entered for this image, 25 points if the other player has entered the same work in that session, and 5 points for a word that has previously been entered by another user.

It’s a really neat idea and quite a different approach to classifying images than is used by the Zooniverse projects. The attractive thing about a game approach is that the user gets immediate feedback on how they’re doing. I know that many MWP users regularly ask for feedback on their classifications. The problem with giving feedback, however, is that we don’t want to bias the users towards any particular kind of bubble drawings – we want you to tell us what a bubble looks like. Artigo gets rounds this very nicely by giving feedback based on what other users think, rather than what the art historians think.

This post is part of Citizen Science September at the Zooniverse.

The Most Distant Bubble?

A little while ago Sarah Fitzmaurice, a work experience student at Zooniverse Oxford, spent a week working with the Milky Way Project database. She did some fun things with the data, including plotting the locations of many of the bubbles according to their distance from us. For many, the current canonical view of our own Galaxy comes from a combination of data sources, compiled by Robert Hurt, working at NASA JPL. The image is shown below, and you may recognise it: we use it as our Twitter/Facebook avatar. It is an artist’s impression based on several data sources and guided by astronomers.

The Milky Way may be our home in the Universe but we know startlingly little about it. On key missing piece of information for many objects in our Galaxy is their distance from us. From the Spitzer data alone, we do not know the distance to the bubbles in the MWP. For our first Data Release paper, we compared the MWP Bubble catalogue to known objects, some with distances, and this allowed us to find  out how far way some of the bubbles are. This enables us to investigate how large and sometimes how massive they may be.

During her work experience week, Sarah plotted the bubbles with known distances onto Robert Hurt’s map of the Milky Way. The result is shown below. The bubbles are marked with crosses, and the size of the cross shows the relative size of the bubble. The distances to these bubbles were derived by comparing them to a known set of radio sources that are expected to look like bubbles in Spitzer data.

You can see that the bubbles generally follow the distribution of spiral arms and that it is easier to see the bubbles nearby than those farther away. This is good because it is roughly what we expect. This map also allows us to easily spot the isolated, nearby or most-distant bubbles in the project. Much of Sarah’s week was spent looking at each of the interesting bubbles and finding out some more about them.

Although there may well be more distant bubbles in the catalogue, Sarah’s map provides a candidate for ‘most distant bubble’ in the MWP. It is one of a pair of bubbles located on the far side of the Perseus arm, almost 45,000 light years away from the Sun – in the top part of the above image.

Using the new MWP coordinates tool we can take a look at this distant object, and two nice images of it are shown below. Our ‘most distant bubble’ is actually located within another larger, clearer bubble, the image of this is also given. This is a line-of-sight effect and they are not necessarily near each other.

This bubble is located literally on the other side of our Galaxy and is roughly 15 light years across. The fact that the two bubbles are positioned on top of each other makes it hard to decide which one is farther away. There are many more instances where bubbles lie on top of each other where it would be impossible to decide which is actually on top of which. The nebulous material of which these objects are made makes them hard to disentangle. In this case there are stars and IR objects on top of the smaller bubble that make it easier to pick out the nearer and farther bubble.

In this case, the distance value is derived from a radio source that we expect to be associated with a bubble. Both of these bubbles lie at roughly the correct position to be associated with the radio source. Since we know the radio source is very far away, we can say that the smaller bubble is most likely the object associated with the radio source.

These kinds of confusing caveats are one of the things that make Galactic astronomy difficult and challenging. For these reasons, this might be the most distant bubble we know of in the MWP – or it might not. Either way, this awesome little bubble has provided the opportunity to discuss the ways that we determine the distances to objects in the MWP catalogue, and how doing astronomy in our cosmic backyard is tricky territory indeed.

A bright bubble around a dying star

The bright bubble around Luminous Blue Variable star G24.73+0.69

A few days ago Milky Way Project user suelaine posted an image of this pretty bubble on the Talk forum, asking whether it was a supernova. As supernovae – or rather, the debris that’s left behind after they explode – often have this kind of shape, I initially thought she was right. But when I looked up the coordinates on SIMBAD – the astronomer’s guide to the Galactic sky – I discovered it was a beautiful example of a more peculiar type of object: a Luminous Blue Variable star (LBV).

[As an aside, the SIMBAD page for the object is a little confusing, as it’s identified on there as a Be star – a rapidly rotating B star. But when you look down the page at the references, it’s clear that the star has since been identified as an LBV star, probably even more massive than originally thought.]

LBV stars are massive stars, often with a few tens of times the mass of the Sun, that are approaching the end of their lifetimes. The fuel in their cores, needed to maintain nuclear fusion, is running out. This makes them unstable, causing them to flare up at intervals. As they’re not able to hold on to their outer layers, powerful winds eject matter into the surrounding interstellar medium during these eruptions, and the star can be sen to brighten significantly over several months. LBVs are on their way to exploding as supernovae.

The evolution of such massive stars once they run out of fuel proceeds very quickly, so these objects are extremely rare: only around a dozen are firmly known in the Milky Way Galaxy. The best-known examples are Eta Carinae and the Pistol Star,  perhaps the most luminous star in the entire Galaxy. Because there are so few LBVs to study, there’s a lot about them we don’t know.

This particular LBV, prosaically known as G24.73+0.69 (its galactic coordinates), was discovered in 2003, and lies at a distance of around 5 kpc, or 16000 lightyears. As well as the compact orange bubble this larger view of its surroundings shows that there is a second, larger shell, more bipolar in shape than a true ellipse. The star and its environment were studied in detail in a very recent paper by Argentinian astronomers Petriella, Paron and Giacani. They discovered a dense molecular shell tracing the outer bipolar nebula. They suggest that the inner compact bubble is the result of an LBV eruption, and the outer bipolar shell perhaps caused by more gradual mass loss during the star’s “regular” lifetime.

Interestingly, they also find evidence that perhaps new stars are forming near the lobes of the larger shell. They suggest this may be triggered star formation in the swept-up gas, but their observations can’t confirm that.

I didn’t know much about LBVs myself, so I was pretty excited with this find. Keep posting your interesting objects to the forum – perhaps we can find more LBVs or other cool types of objects.

If you’re interested in learning more about this interesting star, here’s the full paper reference:

Petriella, Paron & Giacani. The molecular gas around the Luminous Blue Variable Star G24.73+0.69. Astronomy & Astrophysics vol. 538, A14 (2012) [pdf available from Arxiv]

Triggered Star Formation

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There’s a new Milky Way Project paper out on the arXiv. It was submitted to the Astrophysical Journal last week and concerns the topic of the triggered formation of massive stars. This study was lead by Sarah Kendrew and utilises the results of the first MWP paper (our catalogue of bubbles).

One of the main reasons for undertaking the MWP was to produce a large bubble catalogue that would allow statistical studies of star formation sites in our Galaxy. In the end we produced a list of bubbles ten times larger than the previous best catalogue in our first data release (DR1).

In this new study, we’ve used statistical techniques to see what correlations exist between the MWP bubbles and the RMS Catalogue: a well-used catalogue of infrared sources along the Galactic plane (a similar region to that covered by the Spitzer data used in the MWP).

The paper looks for any signs that there is a correlation between the positions of RMS sources and the positions of the MWP bubbles. Specifically we’re trying to see if such massive young stellar objects (MYSOs, stars being formed) are most commonly found on the rims of bubbles. If this is true, then it adds to evidence for a mode of star formation where the formation of some stars triggers the formation of others. In this case, young, hots stars blow out a bubble in the interstellar medium. During this process, clumps of material occur in which new stars condense and form.

This new study finds a strong correlation between MYSOs and the MWP bubbles. We find that Atwood thirds of the MYSOs surveyed are associated with bubbles and 22% are associated with bubble rims. We also see that larger bubbles are more likely to have MYSOs on their rims – though one of the main issues we encountered is that the effect of line-of-sight confusion makes the situation complicated.

This second paper is the first to follow on from the MWP DR1 paper, and there are more planned. You can read the paper on arXiv. The Milky Way Project itself, and this study, we’re presented at the UK/Germany National Astronomy Meeting this week in Manchester.

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Milky Way Project Refresh

We’re excited to announce that we have updated the Milky Way Project to show you more bubbles and to produce even more science! After creating our catalogue of 5,106 bubbles earlier this year, we’re aiming to try and refine and improve our measurements of the MWP Bubble catalogue by asking you to measure each and every bubble in greater detail. This means that for a while we’ll no longer be displaying images from across the plane of our Galaxy, but instead we’ll just be showing you images of regions where you told us that bubbles are located.

Our recently accepted Data Release 1 (DR1) paper, ‘A Bubblier Galactic Disk‘ is already online and being used by astrophysicists to help better understand star formation in our Galaxy. Later this month we’ll be presenting the MWP at the UK/Germany National Astronomy and SEO Consultant Meeting in Manchester. We will hopefully be able to bring you some updates at that time so you can follow along. In that paper we estimated that our rate of discovery of new bubbles had declined over time to the level where only a few new bubbles were being discovered each month. This make sense of course. The more people that inspect all the images on the site, the less likely it is for a bubble to remain undiscovered. What becomes important are the multiple, independent drawings of each bubble. To reflect this, we have updated the MWP site to shift from showing random portions of the Galaxy, to showing the places we believe there are bubbles – based on your classifications. Each image you are now shown on the site contains one of the 5,106 bubbles contained in the DR1 catalogue. It’s seems really fitting that the MWP community is now inspecting the very catalogue it created.

This update to the site has two effects. First of all it means that you are able to see each bubble more clearly and thus make more precise measurements of their shape, size and thickness. It also means that you see a lot more bubbles! There now ought to be at least one bubble in every image, which is a lot of fun. It also means that Talk has been updated with a host of new bubble-centrd images, showing off all 5,106 of the DR1 catalogue’s bubbles.

We have made some other updates to the site as well. We have put up our contributors page, which lists the names of everyone that made the DR1 paper possible. We have also finally added the term ‘Yellow Ball’ to our list of objects you can mark in images. The #yellowballs are a term coined on Talk by the MWP community and turn out to be interesting to researchers at they appear to represent ultra-compact star forming regions.

Don’t forget to follow us on Twitter @milkywayproj for the latest updates, and our Facebook page too.