The news that an Earth-mass planet has probably been discovered in orbit around alpha Centauri B has a big impact on Project Icarus. If this news is confirmed, then it means our nearest stellar neighbor has at least one planet. Overnight, alpha Centauri has potentially become a more interesting target for Project Icarus.
Professor Ian Crawford, lead designer for Project Icarus science and target selection, has already written an article in which he favors alpha Centauri as a target (Which Exoplanet to Visit?). After the latest news was released, Crawford added:
“The alpha Centauri system was already the front runner as a Project Icarus target, because of the three different types of star it contains. So the discovery of a planetary system just reinforces the system’s priority as a target.
“Although this particular planet is too close to its star to be habitable, if the discovery is confirmed it is very likely that other planets exist at greater orbital distances. These could potentially be habitable and, if found to be present, would increase the priority of the system even more.”
Crawford sounds a note of caution:
“Clearly this was a very difficult measurement to make and the statistics, while formally good enough to claim a discovery, are not as great as one would like. It will be very interesting to see the results of follow-up observations. Hopefully these will confirm this detection.
“Moreover, it also appears that even these very sensitive radial velocity measurements are incapable of detecting Earth-mass planets in the alpha Centauri B habitable zone (HZ) — with the lowest mass detectable at HZ orbital distances being 4 Earth-mass super-Earths. Therefore, despite the very real cause for excitement about this detection, it may still be a long wait before we know whether or not this star also has Earth-mass planets in its habitable zone.”
So we proceed with Project Icarus bearing this caution in mind, but buoyed by the excitement of this potentially amazing discovery if it is confirmed.
Crawford’s paper Astronomical Considerations Relating To The Choice Of Target Star can be found in JBIS Vol 63 No 11/12 Nov/Dec 2010.
A list of Crawford’s publications can be found on his website.