Category Archives: Images

Our Sentimental Galaxy

More than 25,000 comments have been made on Milky Way Project Talk since the project began in 2010. That’s a lot of content in itself – beyond the main classification data from the MWP’s main interface.

I’ve been using the Python-based Natural Language Toolkit (NLTK) to perform what’s called sentiment analysis on Zooniverse Talk data. Some of the most stunning results come from the Milky Way Project’s rich dataset.

The process is oddly simple – thanks mostly to NLTK’s great documentation. You train an algorithm to recognise positive and negative words and phrases in text – and then go though all the MWP subjects in Talk looking at the things people say about them, and recording whether the comments are positive or negative. If a comment is really positive (e.g. people say ‘stunning’, ‘wonderful’, ‘brilliant’) then it gets a score around 1. If it’s negative (e.g. people say ‘horrible’, ‘stupid’, ‘disgusting’) then it gets a score of 0. Of course most subjects come in somewhere in between.

So here are the results: the 20 most-positively commented on images from the MWP (click to embiggen). It’s a lovely set, and you can see why people were so positive about these images.

On the flip side, here are the 20 most-negatively commented on images. You see a mix of difficult to classify and blown-out images.

I’m now looking at ways to use this sort of sentiment analysis to extract interesting images from Talk and highlight them to moderators and science teams. It’s something I’ve been toying with on-and-off for several projects – not just the MWP. The Zooniverse Advent Calendar seems like a great time to share and see what people think of this idea.

You can find my code on GitHub along with other examples. As well as the MWP there are galleries for Galaxy Zoo and  Snapshot Serengeti.

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A New Batch of Milky Way Project Data Has Arrived

After a busy December and January we ran out of data a few weeks ago after 600,000+ classifications of the new images – but the wait is over! Last night a whole new, bigger, batch of data was added to the Milky Way Project. Here’s a few examples of what you might see in the data:

These new data come from the GLIMPSE 2 survey – a comprehensive survey of the middle-part of our galaxy in the infrared. We’re also going to be adding in some of the GLIMPSE 1 data (from the old version of the Milky Way Project) back into the site but with the new colour stretch. We’re doing to that to check the system works, but also because new features and structures will be visible with the change in data and colour palette.

We’re still crunching the data from the new classifications, but we’ve been able to extract lists of galaxies, EGOs and star clusters that you have found. We hope to share those with you soon.

So hop on over the milkywayproject.org and let’s add another 600,000 classifications and continue mapping the galaxy.

New Milky Way Project Poster

I’ve been diving into the bubbles database recently and ended up creating cutouts of all 3,744 large bubbles from the DR1 data release. From there it was an easy enough job to create this new Milky Way Project poster. It uses all 3,744 bubbles at least once (several are used more than once).

MWP Logo Mosaic of Bubbles

I’m currently working on three new Milky Way Project papers and will be blogging about them in the next weeks and months.

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.

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]

Exploring the MWP: Coordinates and SIMBAD

One of the most common questions posted on Milky Way Talk is “What is [that thing] in this image?”, and science team members try to respond to some of those where we can. The galactic plane is so incredibly rich at these infrared wavelengths and the Galaxy is so vast that even with the combined experience of the whole science team we usually don’t know the answer.

To help everyone out, we’ve created a new tool that lets you search one of the world’s best astronomical databases from within the Milky Way Project. SIMBAD is a huge astronomical database, maintained by the Centre de Données astronomiques de Strasbourg (CDS) and contains 7 million astronomical objects documented in the literature. When astronomers want to see what is known about any part of the sky, many of them start with a SIMBAD search. Our new Coordinates Tool lets you search the images from the MWP for SIMBAD data, to help show you what different objects are.

The Coordinates Tool

You access the new Coordinates Tool directly at http://www.milkywayproject.org/tools/coordinates/

This will take you to a default page, exploring the area around the coordinates 0, 0. The MWP images use the galactic coordinate system, which expresses positions in galactic latitude and longitude – concepts that should be familiar if you know about geo-coordinates here on Earth. The “equator” of the galactic coordinate system (the latitude = 0 position) is roughly coincident with the disk of the galactic plane.

Looking down on the galactic plane (Image: NASA/JPL-Caltech/R. Hurt)

In this picture, the galactic latitude tells you how much an object lies above or below the plane of the Galaxy, and the longitude specifies the angle away from the Galactic Centre. The above image shows a schematic diagram of what we think the Milky Way Galaxy looks like, with an indication of our own location and a galactic longitude grid. Galactic latitude runs from -90 to 90 degrees, and longitude from 0 to 360 degrees, although sometimes you may also see it noted as -180 to 180 degrees.

To search the area around any set of coordinates, you simply include them in the URL for example, to search one of my favourite regions, at longitude 18.4 degrees and latitude 0.2 degrees, you would visit

http://www.milkywayproject.org/tools/coordinates/19.0/0.0/

This will display one of the MWP images that containing those coordinates (see below). It will also list the other MWP images containing these coordinates. This lets you explore the region at different scales and in different contexts. The specified coordinates are shown on the image with a box. A link to the image’s Talk page is also included.

You’ll see that as you move the cursor around the image, coordinates are displayed to help you navigate. You can double click on any point to jump to that centre and see the images available. By default a small, square box is drawn onto the target area. If you want to draw a specific box you can give the width and height (in arc minutes) as URL parameters:

http://www.milkywayproject.org/tools/coordinates/19.0/0.0/?h=15&w=30&zoo_id=AMW102de6d

You can also reach the Coordinate Tool from the main Explore page. just double click on the map to just to more detail on that region. A link has also been placed on the images in the My Galaxy section of the site, for logged in users.

SIMBAD

Also present on the Coordinate Tool is a button with the words ‘SIMBAD Search’. Clicking this performs a SIMBAD search on the current viewing area and displays the results directly on the image. Here’s an example from the URL I gave above:

Any objects SIMBAD finds in the astronomical literature are displayed as circles. If,you hover your mouse over them you will see their object name and type. Clicking on these objects takes you to the objects page on the SIMBAD site, where you can find out more.

Many of the objects found in the MWP will be stars – the galaxy is full of them! – and many will be IRAS and 2MASS objects – these names derive from previous infrared surveys that mapped the regions covered by the MWP data. In the above image you can see one 2MASS object near the centre of the bubble on the right:

The SIMBAD page for 2MASS J18252813-1224187 explains that may be an Asymptotic Giant Branch (AGB) star. These objects are interesting, and there are plant of them to be found in the MWP images.

Some interesting regions that are worth a SIMBAD lookup with the tool include the rim of a broken bubble, a dying star and the pulsating heart of a gorgeous bubble.

This tool is still a bit rough around the edges, but we are keen to invite comments and ideas from anyone that would like to try it out. You can either leave comments on this blog post, or email us on team@milkywayproject.org. We have more updates on the way!

First Paper: A Galaxy of Words

The first Milky Way Project science paper has been submitted! We sent off our manuscript to the Monthly Notices of the Royal Astronomical Society just yesterday – exactly one year since the launch if the project. Now we wait for the process of peer-review to get kick-started. Our paper will be sent to an independent referee – another researcher in astronomy – and usually we would then get some corrections along with a thumbs-up or -down for publication in the journal.

In the field of star formation it is customary to wait until the referee has given us the OK before we publish a pre-print of the paper online. So we will keep you posted on progress – including posting a PDF of the paper when its time – as we move toward publication.

In the meantime, as part of the Zooniverse advent calendar we’ve produced a slightly different version of the paper for publication right now! This ‘word galaxy’ is a representation of the content of the paper – but in beautiful spiral form. The most common words in the paper were MWP (214 times) and bubbles (283) so they are largest. The words scale all the way down to disk (3 times) and ‘tend’ (2 times).

Have fun exploring the paper in this form until we can get the real one to you in the next few weeks.

[Download large version 2.6 MB]