Finished with Galaxy Zoo: UKIDSS!

I’m happy to announce that thanks to the hard work of more than 80,000 volunteers, we’ve recently completed classifying the infrared images of galaxies taken from the UKIDSS survey! There were more than 70,000 images of galaxies on the site that you helped to classify; once the data are reduced, one of our main goals is to compare your classifications to those from the Galaxy Zoo 2 project and study how morphology changes as a function of the wavelength in which those galaxies are observed. Melanie Galloway, a PhD student at the University of Minnesota, will be focusing on these this summer as part of her thesis work.


Some early results have shown that, as we predicted, features like galactic bars are often more prominent in the infrared. Below is a nice example of this phenomenon: the image is of the same galaxy (SDSS J115244.84+054059.1). In the optical image on the right (from GZ2), you can see a spiral galaxy with lots of star-formation, but the clumpy morphology of the gas clouds can hide the shape of the bar in the galaxy. In the UKIDSS image on the right, the blue gas clouds from star formation aren’t picked up in the infrared, and the stellar bar is much more clearly visible. This is supported by your classifications: the probability of a bar jumps from just 25% in GZ2 to 67% in GZ:UKIDSS.

Two images of the same galaxy; the infrared UKIDSS image on the left, and the optical SDSS image on the right. The strong bar in the galaxy is much more obvious in the infrared image.

Two images of the same galaxy; the infrared UKIDSS image on the left, and the optical SDSS image on the right. The strong bar in the galaxy is much more obvious in the infrared image.

This marks the third set of galaxy images we’ve completed since the relaunch of Galaxy Zoo in 2012 (following the high-redshift CANDELS images from Hubble and the artificially-redshifted images from FERENGI). There are still tens of thousands of galaxies from the SDSS left to classify in Galaxy Zoo, though, and we’ll be adding new sets of images in the coming months. Thanks again for your help, and we’ll report on the results of the UKIDSS data as it comes in!

About Kyle Willett

Kyle Willett is a postdoc and astronomer at the University of Minnesota. He works as a member of the Galaxy Zoo team, and gets to study galaxy morphology and evolution, AGN, blazars, megamasers, citizen science engagement, and many other cool things.

4 responses to “Finished with Galaxy Zoo: UKIDSS!”

  1. planetaryscience says :

    I’ve noticed that bars are fairly common in galaxies, much more common than true spirals. However, often bars are disguised. Like you said, in GZ2 people classified bars 25% of the time, but as I have been making collections based on morphology in GZ talk, I can tell you that at least 75% of spiral galaxies contain bars. (I have 325 barred spirals & just 174 spirals)

  2. Kyle Willett says :

    They’re definitely common, although that number is higher than most estimates in the literature. Current estimates from multi-wavelength surveys (Menendez-Delmestre et al. 2007; Sheth et al. 2008) have it as high as 67%. We’ll use the GZ:UKIDSS data to test this with a much larger sample.

    • planetaryscience says :

      Kyle, it appears that the data I’ve collected since suggests what you say is true. Due to a calculation error on my part, and subsequent collection of more barred spiral/spiral galaxies (408 versus 211) the amount of barred spirals versus spirals is about 65.9% +0.5% -1.5%

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