A Valentine's Day Challenge

We’ve been a little quiet over at Merger Zoo recently.    In the first three months of this project, you have viewed nearly two million simulations for nearly 40 different galaxies.   Of these two million, you have picked about 30000 galaxies that we have been doing further investigations on.   In short, we have been extremely busy because of all your hard work!

Because of Valentine’s Day, we decided to pick an unusual galaxy for our target today.  As you can see, it looks very similar to a Valentine’s Day heart.   If you look carefully at it, you can see it is actually two “collisional ring galaxies” that overlap each other.   In general, we know that collisional ring galaxies are created when an intruder galaxy passes near the center of a target galaxy.  The orbit has to be nearly perpendicular to the plane of the unperturbed galaxy’s disk.    During the close passage, the extra gravity of the intruder draws in the orbiting stars and gas.   After the intruder leaves, the stars spring out in a circular wave like ripples in a  pond.   Since the gas from the original galaxy is compressed into rings as well, most of the star formation in these systems tends to be in the outer ring of the galaxy.

Collisional ring galaxies are rare beasts, and one of my favorite types of interacting systems.   This is the first example that I have ever seen of two ring galaxies created in the same collision.   It seems like creating this type of system should be possible, but we aren’t sure how to create models that closely reproduce this beautiful system.   As always, we need your help!

The challenge will be to find a collisional ring galaxy that close matches the heart-shaped rings of the real system.   The star in the upper left is almost certainly a red herring  (or rather a red dwarf star) that has nothing to do with the collision.  Try using the explore feature until you find a few close examples of double ring galaxies, and then use the enhance feature to tune it further.   This approach works pretty well for most of the systems we have played with, although you have to be patient!   We played with this system on our computers, and found some models that had two rings but didn’t reproduce the heart-shaped structure of this system.  We know from experience that you can do better.   Please make sure to save your work at the end so we know which system is the best of your best!

In a few weeks, we will present the best model or models in this blog.  We will also present some of the models you found of the other galaxies.   We should have a few other surprises coming up soon as well.

The Valentine system is also a gift from all of us at the Zooniverse to our incredible volunteers.   We couldn’t do this science without you.  As always, thanks for your on-going contribution to our project and the rest of the Zooniverse.

-John