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From ‘Hot Jupiters’ to Terrestrial Worlds

If you’re going to have a conference on exoplanets, there is no better venue than l’Observatoire de Haute-Provence. It was here, just ten years ago, that Mayor and Queloz discovered the first planet orbiting a main sequence star outside our own Solar System. The star was 51 Pegasi, a name that will surely be recalled for generations as the first confirmation that planets exist around other stars. And attendees at a late August conference celebrating the discovery had much to say about the course of future exoplanetary developments.

David Charbonneau (Harvard-Smithsonian Center for Astrophysics) summarizes the conference findings in his paper “Hot Jupiters: Lands of Plenty,” now available on the arXiv site. A major issue stands out: the huge leap in precision for radial velocity observations of the sort that bagged 51 Pegasi’s planet, allowing researchers to monitor a wider group of stars than the F, G, K and early M-class dwarfs that have been the focus heretofore. The new precision is energizing more finely targeted searches for planets around low-mass stars, young stars, evolved stars and binary systems, among other investigations.

We’re not yet up to the kind of Doppler precision that would allow detection of a terrestrial world in the habitable zone of a low-mass star, but Charbonneau says that data presented at the conference hints that still further improvements are close. Another major player in sharpening our exoplanetary focus: the role of space-based observatories like Spitzer and Hubble, the latter of which has been spectacularly effective in the study of planetary transits.

Charbonneau also reports on a poll he conducted at the conference. The paper breaks down the answers, two of which catch the eye:

  • Most participants believe that we’ll have detected 1000 exoplanets within ten years;
  • The majority of attendees believe extraterrestrial life will be detected before 2050, but a significant number believe it will only be detected later than that or not at all.
  • Centauri Dreams‘ take: Charbonneau’s final thought mirrors my own: “With the exciting discoveries of the previous decade as our guide, we can only assume that the prevailing wisdom will, once again, be proven wholly unjustified.” Which is probably the surest thing to be said about a survey of practitioners in a field this mutable– remember that ten years ago, the very idea of a ‘hot Jupiter’ seemed too fanciful for words. Exoplanetary detections continue to challenge everything we know about planet formation, and as the conference also made clear, we have nothing but guesswork to supply about the incidence of terrestrial worlds around other stars. It is, in short, an absolutely extraordinary time to be alive and practicing science.