With astrometric accuracies of 0.03 mas (achievable with HST spatial scanning), centroid shifts caused by Jovian planets are detectable at separations of up to 2′′.0 (corresponding to 2.6 AU at the distance of Proxima), and centroid shifts by Earth-mass planets are detectable within a small band of 8 mas (corresponnding to 0.01 AU) around the source trajectories. Jovian planets within a band of about 28 mas (corresponding to 0.036 AU) around the source trajectories would produce a brightening of the source by > 0.01 mag and could hence be detectable.
From the .pdf above:QuoteWith astrometric accuracies of 0.03 mas (achievable with HST spatial scanning), centroid shifts caused by Jovian planets are detectable at separations of up to 2′′.0 (corresponding to 2.6 AU at the distance of Proxima), and centroid shifts by Earth-mass planets are detectable within a small band of 8 mas (corresponnding to 0.01 AU) around the source trajectories. Jovian planets within a band of about 28 mas (corresponding to 0.036 AU) around the source trajectories would produce a brightening of the source by > 0.01 mag and could hence be detectable.If I understand this correctly, microlensing would only be able to detect Jovian mass planets inside Proxima Centauri's habitable zone (?)
If I understand the methods used by the Pale Red Dot team correctly, they have ruled out anything smaller than 3 times Earth's mass inside Proxima's H too, which is a bit of a bummer.
OK, so brightening microlensing could not detect a potentially habitable Earth or super-Earth inside Proxima's HZ in this case. If I understand the methods used by the Pale Red Dot team correctly, they have ruled out anything smaller than 3 times Earth's mass inside Proxima's H too, which is a bit of a bummer. Don't get me wrong, I'll take any and all confirmed exoplanets, but the potentially habitable ones are just that much more exciting.
As far as I am aware , the best Doppler signal to date has a lower mass , msini and all , of just 1.2 Mearth with an 18 day period , so well within the Hab zone.
Quote from: Ashley.Baldwin on 04/03/2016 12:36 pmAs far as I am aware , the best Doppler signal to date has a lower mass , msini and all , of just 1.2 Mearth with an 18 day period , so well within the Hab zone.How certain are they of this? I'll be impressed if it's correct but I'd assume the odds for a planet beyond the hab zone are just as likely. Either way, we all want to know what Proxima has circling itself.