The news from Transitsearch couldn’t be better. Long a champion of amateur involvement in the exoplanet hunt, I was delighted to see, via Greg Laughlin’s systemic site, that this globally dispersed team of amateur astronomers is behind the confirmed transit observation of the planet HD 17156 b. Amateurs in Italy, the Canary Islands and California made key observations in early September, with confirmatory data coming in from Massachusetts and California on the night of September 30/October 1 as observers heeded Laughlin’s online call to participate.
Greg has the details and more about the individual observers at his site. The Transitsearch mode is to look at known planet-bearing stars during those times transits might conceivably occur. And it makes stunningly good sense because of two facts: 1) The tools available to dedicated amateurs today are fully capable of this kind of high-quality work; and 2) Telescope time at the major observatories around the world is obviously limited. The Internet allows this network of amateurs to collaborate, making serious contributions to our exoplanetary knowledge.
HD 17156 b is quite an interesting place. Its radius seems to be a bit larger than Jupiter’s, while its orbital period is 21.2 days. Note that this is almost four times longer than any other known transiting exoplanet. Note too that HD 17156 b’s orbit is highly eccentric, so much so that the planet experiences a 26-fold variation in the amount of flux it receives from its star. Interesting weather patterns doubtless emerge, as Laughlin notes, with the night side glowing with its own radiation. I poached the image below from the systemic site, but have a look at the full animation, showing Jonathan Langton’s hydrodynamical study of this world.
So there’s the method: Use Doppler radial velocity data to find exoplanets and check for transits with an ad hoc network of amateurs coordinating their work over the Internet. Can the Spitzer space telescope catch HD 17156 b in secondary transit? If so, says the discovery paper, that will enable “…a much-improved constraint on the still-uncertain radius of the parent star. In the event that secondary transits can be observed, a direct measurement of the excess tidally generated luminosity from the planet is a distinct possibility…”
The paper is Barbieri, Alonso et al., “HD 17156b: A Transiting Planet with a 21.2 Day Period and an Eccentric Orbit,” available online. Nice work!