Re: Looking for "New Earth" around Alpha Centauri

From: Steve Willner (willner_at_cfa.harvard.edu)
Date: 10/29/04 

Date: 29 Oct 2004 18:22:08 -0400

In article <adbf5bc1.0410282117.61b55b23@posting.google.com>,
 abdul.ahad@ntlworld.com (AA Institute) writes:
> I wonder if ground based interferometry
> arrangements using large telescopes like the Keck along with adaptive
> optics, computerised processing, filtering, etc. could manage such a
> task.

There are some attempts along those lines, but:

1. They (at least the ones I know about) work in the infrared, where
   the star/planet ratio is smaller.

2. They are attempting to find "Jupiters," not "Earths," so the
   planet is a lot brighter.

The work I know about uses a "nulling interferometer," in which two
beams are combined destructively for the central source but not for
surrounding sources. If everything is perfect, the central source
(the star) vanishes, but nearby sources (planets) are not cancelled.
Of course in the real world, there are plenty of things that are not
perfect, and the question is how small the residuals can be.

Typing "nulling interferometer" into an ADS abstract search shows
eight papers in refereed journals and more than forty in conference
proceedings in the last two years, though some of these may refer to
space-based instruments. This is definitely work in progress. 

-- 
Steve Willner            Phone 617-495-7123     swillner@cfa.harvard.edu
Cambridge, MA 02138 USA                 
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