Another circumstellar disk...

[ajtribick]

Sharpest image ever obtained of a circumstellar disk

Now why is it that all these circumstellar disks point to really wide solar systems with planets in crazy eccentric orbits? Is it that planets in near-circular orbits wouldn't lead to such visible clumping in the dust so we don't notice it, or is it likely that our solar system is a weird freak exception to the norm of hypermassive gas giants close to their stars and distant planets on elliptical orbits?

[selden]

My understanding is that the stars with discs where lumps have been seen are relatively young: hundreds of millions of years old. In contrast, our solar system has had billions of years for the planets to interact and circularize their orbits.

Also, remember that the primary method currently used to detect planets around other stars looks for doppler shifts in their spectra. Large, quick shifts are easier to detect, and they're caused by close, large bodies. Planetary systems organized like our own would produce doppler shifts that are very hard to detect: small amplitudes and slow changes.

[ajtribick]

Ok, so outer planets in eccentic orbits are easier to detect by Doppler because they move fast at perihelion, thus causing a quicker change than a circularised planet which moves slowly for the entire duration of the orbit?

[selden]

Hmm. Maybe. You'd have to be looking at just the right time to see the doppler shift at such a planet's perihelion, though.

I was trying to say that the doppler shift detection method is most sensitive to massive planets that have short orbital periods.

The article you linked to seems to claim that the elliptical structures were directly observed, not deduced from doppler shifts.