Today was the (first) Tri-state Astronomy Conference, organized by Ari Maller (CUNY CityTech) and Marla Geha (Yale). There were good talks all day, with quite a few (though not all) New-York-area institutions represented. I learned the most from Ben Oppenheimer's (AMNH). He made a pitch for exoplanet research and showed me several things I had not thought about or seen before:
- Although the properties of a star are set, pretty much, by mass and chemical composition (and age), this is not even close to true for planets. Look at the Solar System! This shows that once you get to low mass, formation history and environment matter, deeply.
- There is no clear distinction between brown dwarfs and planets, observationally. The differences are entirely related to discovery technique! In mass and orbital radius distributions, planets and brown dwarfs overlap, and—in the absence of good theories—there is no reason to make hard distinctions (although we all do).
- Polarimetry plus coronography combined do much better than either alone, and it is possible to see reflected light from planets and proto-planetary disks at incredibly small luminosity ratios with the combination. Coronography is limited, at the present day, by speckles (wavefront irregularities), which are introduced not just by the atmosphere but by every optical surface, of course.
I asked Oppenheimer about modeling the speckles to remove them, and he said that they are very complicated and change with time and wavelength. Of course that is true, but that also helps with modeling them. A better answer is that the modeling can only happen with the intensity data, whereas improving the optics makes use of the amplitudes and phases, a space in which you can cancel out (rather than just model) your instrument issues. So Oppenheimer is right to be putting time and money into great optics, and to work on software only after optimizing the hardware as much as possible.