Archive | January 2014

Disk Detective and Planet Hunters

A few folks have asked us: what’s the relationship between Disk Detective and Planet Hunters? Planet Hunters, of course, is the Zooniverse citizen science website that invites users to examine data from NASA’s Kepler mission to search for extrasolar planets.

The success of Planet Hunters helped inspire us to launch Disk Detective!  But beyond that, there are several scientific connections between the two projects. Both are about extrasolaKepler Field of View Star Chartr planets. As you probably know, in Planet Hunters, users look at measurements of a star’s brightness, checking for sudden dips that could indicate a planet crossing in front of the star (called “transits”).  In Disk Detective, we search for the homes of planets: stars surrounded by disks where planets form and often dwell.

Let’s talk more specifically–about what stars the two projects have in common.  First of all, the data from the WISE mission that we’re examining at Disk Detective covers the whole sky.  So it overlaps with everything, including the part of the sky that Kepler/Planet Hunters has already studied and whatever parts of the sky Kepler will image in the future. Indeed, the part of the sky Kepler has already examined has already been searched for disks at least once; Samantha Lawler and Brett Gladman claimed to find eight debris disks around stars with Kepler planets in 2012, using data from the WISE mission. However, further studies of the Kepler field were unable to replicate this result. The map above illustrates the current Kepler field, mostly located within the constellation of Cygnus.

But there will be more such Kepler/WISE disks for us to find via Disk Detective and Planet Hunters.  For one, both the Kepler and WISE databases have improved substantially since that work was done.  Kepler has found more transiting planets, and WISE scanned the sky again, leading to the new ALLWISE data release this fall.

Moreover, plans are afoot to extend the Kepler mission.  The extended mission, called “K2” will search for planets in a different region of sky, near the plane of the Earth’s orbit. Here at Disk Detectives, we will already be searching that region for disks.  And I’m pretty sure the new K2 data will be searchable at Planet Hunters as well.

So stay tuned–and keep digging for new disks!  You might find one around a star that Kepler has already found planets around, or that it will find planets around soon.  And even if there is not a direct match, we still learn by combining the statistical information from both surveys about how and where planets form.

“It has long been an axiom of mine that the little things are infinitely the most important”

Marc Kuchner


Seven Hundred Million Sources. Four Hundred Disks.

It was the curly-haired Dr. David Leisawitz who first told me about the WISE mission. I remember sitting in his office in front of a giant black-green-magenta sky map while he described how the WISE mission would find amazing kinds of disks: disks hosting young planetary systems, disks in old planetary systems, all kinds of exotic phenomena.

He told me how the science team was combing through the data right now by computer to find these disks. But every source had to be verified by eye.

I left David’s office inspired, and eager to find new ways to use the vast database from the WISE mission. So I called on Dr. John Debes, an expert in white dwarfs, a kind of old, dead star. He started digging through the WISE data, finding disks around these white dwarfs—ghosts of dead planetary systems. It was a different kind of search. But again, every source had to be verified by eye.The Vela Molecular Cloud, Imaged with WISE

I started wondering: is it possible that folks are going about this backwards?  What if we could check through the whole WISE catalog by eye, right off the bat?  What would we find then?

I made some quick estimates of how many disks could be find in the database that others had not already found by computer. The WISE mission observed more than 747 million sources all around the sky. My calculations told me that if we went through the catalog using the amazing power of human vision right off the bat, we could find almost 400 debris disks among this sample that nobody else could find. That’s not to mention all the other kinds of disks whose numbers I couldn’t calculate: protoplanetary disks, transitional disks, disks around white dwarfs and other evolved stars.  And there could be other kinds of fascinating objects to find lurking in the data: Kardashev Type III civilizations, metal poor stars, planetary nebulae—

But I still wasn’t confident in the idea.  So I called up Drs. Debbie Padgett and Luisa Rebull, who were also leading large efforts to find disks with WISE.  Debbie discovered a spectacular example of a debris disk that in Hubble images resembled a giant skinny V, probably sculpted by a hidden planet. Luisa had been scouring star-forming regions, finding protoplanetary disks. And once again, in both Luisa’s and Debbie’s WISE searches, every source had to be verified by eye.

The next step was obvious; we wrote the Zooniverse folks and began working on a site. Fast forward through a few years of planning. Now David, John, Debbie and Luisa and I have joined with Dr. Mike McElwain and other experts to become the Disk Detective science team. A few more months of site development and here we are on launch day, ready to work with you, ready to find some disks that nobody else will spot–thanks to your eyes.

So let me take this chance to say that we can’t wait to meet you. I hope you are patient and determined, because it won’t be easy.  But I think the chance to discover a new disk—a whole nascent planetary system—in one shot like this is worth the effort. And who knows what else we will find lurking in the spectacular WISE database, the deepest all-sky infrared survey every undertaken?

Thank you for joining us at Disk Detective. Good luck, and remember that the world is full of obvious things that no one ever observes.

Marc Kuchner