Unusual Orbits for Planetary System

[renormalised (Carl)]

Astronomers at the 216th meeting of the American Astronomical Society announced that the orbit of one of the planets of the Upsilon Andromedae system, planet "C", was inclined at an angle of about 30 degrees to the plane of the rest of the system....McArthur et al, 2010.

(The Astrophysical Journal, Volume 715, Issue 2, pp. 1203-1220 (2010))

The planet possibly ended up in its present orbital inclination due to some violent encounter(s) sometime after the formation of the system. The possible cause was most likely planet to planet scattering due to the gravitational interactions between the planets after their formation. Another mechanism may have been through gravitational perturbations via ups And B, which is a red dwarf that is currently separated from Star A by around 750AU. It's likely that it may have been closer to the main star in the past.

[CraigS]

Gee;

"Previous minimum masses for the planets given by radial velocity studies put the minimum mass for planet c at 2 Jupiters and for planet d at 4 Jupiters. The new, exact masses, found by astrometry are 14 Jupiters for planet c and 10 Jupiters for planet d."

Man that's a huge difference ! They say they improved the precision of Radial Velocity measurements by using one of the Hubble Fine Guidance Sensors (FGSs) on the Hubble Telescope, to come up with this result.

Got to make you wonder about the accuracy Radial Velocity measurements are in general (eg: galaxy RVs). Although, I suppose trying measure the RVs of a couple of planets 44 light years away might be fairly prone to error, however.

Interesting again.
Thanks Carl,
Cheers