When a star flared briefly, astronomers knew it was because a dimmer star had passed directly in front, acting as a lens with its gravity to focus light. Unfortunately, they couldn't find the star. This was important, because the brief microlensing event also turned up the fact that this lensing star has a planet. Astronomers have used the power of the Hubble Space Telescope to find this dim star two years after the lensing event. Identifying the star is critical, because it allows astronomers to measure its unique characteristics, such as mass, temperature and composition.

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Hmmm. This statement seems a bit misleading to me. It seems "obvious" to me that not all bodies in stellar systems form by simple accretion from a planetary disk. Otherwise we wouldn't see so many systems consisting of multiple bodies of similar mass, like Castor (a bound system of 3 spectrographic binaries) or the more recently discovered brown-dwarf and planemo binaries.

Yes, and it is a little gratuitous to state: "The Hubble observations are consistent with the core accretion model."

So is any other object in orbit about anything, unless it is determined the composition of the planet is inconsistent with the local model.

We have a number of moons, asteroids and comets in our SS that appear to have compostions that are inconsistent with the model. Restating the model exists every time a exoplanet system is uncovered doesn't add credence to the theory, whereas the discovery of dusty ring systems in various states of evolution would. (There are a couple of candidate systems.)

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jwj

It's a big universe out there...is it really unwinding, really burning out?