Centauri A and B continue to stand out as likely venues for terrestrial planets. What a change since the days when it was thought orbits in binary systems like this one would be completely unstable. Today we believe that both the major Centauri stars could support small, rocky worlds within about 4 AU, and that such planets are as likely, if not more so, to form there as around our own Sun. The latter insight emerges directly from the work of Elisa Quintana and Jack Lissauer.
Add to that two other factors: At UC-Santa Cruz, Greg Laughlin and Jeremy Wertheimer have shown that Proxima Centauri could perturb the debris disk surrounding the Centauri stars enough to deliver volatiles to inner worlds there. Laughlin has been arguing the Centauri case for some time now, discussing not just the Proxima factor but pointing as well to the metallicity of Alpha Centauri, which is high enough to provide the kind of materials needed to form planets analogous to Earth.
Keen on detecting such a planet, Laughlin now advocates a radial-velocity investigation of Centauri B, toward which end he has been working up detailed feasibility studies. The method: model terrestrial planetary systems in stable orbits using accepted accretion models, then work out hypothetical observing strategies. The radial velocity measurements thus produced are fed to the downloadable systemic console for manipulation.
So far, so good. In fact, working with this data at the highest time resolution produces clearly readable planetary signatures. “The peak at 351 days corresponds to an Earth-mass planet,” Laughlin writes. “The three neighboring peaks correspond to smaller planets having masses on the order of Mars.”
Remember, these planets are simply simulations. But detecting Earth-like worlds in Centauri space looks to be a workable proposition provided we have time and resources to make the needed observations (Laughlin worked with 96,464 radial velocities obtained in a simulated five-year observing run). And there are numerous complications, not the least of which involve the proximity of Centauri A. Can a special purpose telescope be built to handle these observations, given that existing instruments aren’t going to let themselves be comandeered for the length of time required? Laughlin promises more on system modeling and telescope strategy soon.