Thursday, May 18, 2006

Extrasolar Planets: step close to Earth

ESO PR images and animations

Very interesting Article in Nature today from Lovis et al. Nature 441 305-309 (18 May 2006) [subscription required]

They have three "hot Neptune's" in stable orbits around an interesting star, good old HD 69830 which was found to have a dust disk at ~> 1 AU sugestive of asteroid belt (Beichman et al 2005.
One immediate inference of the Spitzer observations was that this was a good target for planet searches, since where there are asteroids you'd hope to see planets. Sure enough...

Here is the ESO press release

Summary: It is a K0 subdwarf main-sequence star, (6th magnitude, 40 lightyears away) cooler and lower mass than the Sun (by a little bit).
They have detected three planets in nested low eccentricty orbits:

Mass Period Eccentricity
(in Earth masses /sini) in days

10 8.7 0.10 +/- 0.04
12 35.6 0.13 +/- 0.06
18 197 0.07 +/- 0.07

The most interesting thing is the low eccentricity.
The third planet is in the star's Habitable zone
Be interesting to know if it is an gas rich ice giant like Neptune, or rocky with thin atmosphere.
Paper discusses that a bit from a particular theoretical perspective.

Overall: way cool. Be doubly interesting if the third planet had a Triton mass moon, eh?

This would be a good TPF target, if TPF hadn't been killed.
My first impression is that the system is also a "theory killer" - we have close packed fairly massive inner planets in near circular orbits; around a lower mass slightly sub-solar metallicity (-0.08) star.

Ok, big question now is whether there is a Jovian in this planet at > 3 AU.
That would make life very, very interesting for theorists.


Anonymous Anonymous said...

Cool! And only a hop, skip, and 41 light-years away :)

7:46 PM  
Anonymous Anonymous said...

This comment has been removed by a blog administrator.

10:47 AM  

Post a Comment

<< Home