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A Very Unusual System?

Today’s blog post is brought to you by zookeeper extraordinaire Chris Lintott.

Last week Meg visited me in Chicago for two days of number crunching and data discussion and analysis. We got a lot done (and crushed Zooniverse developer Michael Parrish at shuffleboard) and I’ll write more about that soon, but a lot of our talk centered on a very unusual system unearthed by a few persistent Planet Hunters.

Once the team had – prompted by posts at Talk – taken a closer look at the system in question (we’re keeping the name under wraps for now) we were pretty excited, but also slightly worried. The system in question seems to have multiple transits, but they imply that there would be two large planets relatively close to each other. So close, in fact, that a back of the envelope calculation suggests that they would be expected to disrupt each other’s orbits. So unless our rough working is wrong (certainly possible) or we’ve caught the system in an unusual time during its evolution (surely unlikely) then there’s something mysterious here.

That, of course, is the perfect excuse for an observing run. We’re lucky enough to have access to the Keck telescopes on Mauna Kea in Hawai’i (probably my favourite place in the whole world). Observing at Keck is a little different from the telescopes that I’m used to – rather than trekking to the summit where a lack of oxygen can make observing difficult, Keck astronomers observe remotely, either from sea level in Hawai’i or from their home institutions.

The initial goal of our observations wasn’t to confirm the existence of the planets – the star in question is too faint to make that easy – but to rule out obvious problems. In particular, the team were worried that we weren’t looking at a single star, but receiving light from a combination of a nearby star and a background eclipsing binary which would then be responsible for some or all of the transits. If that’s the case then we should be able to see relatively large wobbles revealed by the stellar spectrum as the binary stars move back and forth. These will be larger than the faint wobble induced by the planets (if they exist) and checking whether they exist or not will take no more than a couple of observations, each lasting less than an hour.

I’ll report back on the Keck observations. Fingers crossed!



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