Toward Alpha Cen B b
Yesterday, I gave a talk at the JPL Exoplanet Science and Technology Fair, a one-day meeting that showcased the remarkably broad variety of extrasolar planet-related research being carried out at JPL. In keeping with the wide array of projects, the agenda was fast-paced and completely diverse, with talks on theory, observation, instrumentation, and mission planning.
The moment I walked into the auditorium, I was struck by the out-there title on one of the posters: The Ultimate Project: 500 Years Until Phase E, from Sven Grenander and Steve Kilston. Their poster (pdf version here) gives a thumbnail sketch of how a bona-fide journey to a nearby habitable planet might be accomplished. The audacious basic stats include: 1 million travelers, 100 million ton vessel, USD 50 trillion, and a launch date of 2500 CE.
Fifty trillion dollars, which is roughly equivalent to one year of the World GDP, seems surprisingly, perhaps even alarmingly cheap. The Ultimate Project has a website, and for always-current perspective on interstellar travel, it pays to read Paul Gilster’s Centauri Dreams weblog.
Interest in interstellar travel would ramp up if a truly Earth-like world were discovered around one of the Sun’s nearest stellar neighbors. Alpha Centauri, 4.36 light years distant, has the unique allure. Last year, I wrote a series of posts [1, 2, 3, 4] that explored the possibility that a habitable world might be orbiting Alpha Centauri B. In short, the current best-guess theory for planet formation predicts that there should be terrestrial planets orbiting both stars in the Alpha Cen binary. In the absence of non-gaussian stellar radial velocity noise sources, these planets would be straightforward to detect with a dedicated telescope capable of 3 m/s velocity precision.
Over the past year, we’ve done a detailed study that fleshes out the ideas in those original oklo posts. The work was led by UCSC graduate student Javiera Guedes and includes Eugenio, Erica Davis, myself, Elisa Quintana and Debra Fischer as co-authors. We’ve just had a paper accepted by the Astrophysical Journal that describes the research. Javiera will be posting the article to astro-ph in the next day or so, but in the meantime, here is a .pdf version.
Here’s a diagram that shows the sorts of planetary systems one should expect around Alpha Cen B. The higher metallicity of the star in comparison to the Sun leads to terrestrial planets that are somewhat more massive.
We’re envisioning an all-out Doppler RV campaign on the Alpha Cen System. If the stars present gaussian noise, then with 3 m/s, one can expect a very strong detection after collecting data for five years:
I think the planets are there. The main question in my opinion is whether the stellar noise spectrum is sufficiently Gaussian. It’s worth a try to have a look…