Saturn Like Planets

[Saturn1970]

I am wonder how common are saturn like planets in the Milky Way. I mean planets with the same mass as saturn (~0.3 jupiters), at the same distance from their parent star (9.5 A.U in G2 star types), and with the same yellow coloration of saturn and a ring system. What are the chances for a planet like that to exist? We know that the majority of the jovian planets found have masses higher than jupiter.

What about two saturn-like planets in a same solar system? Would that be common?

[ajtribick]

Our knowledge of planets at large distances from their stars is rather lacking... if you take a look at the Extrasolar Planets Encyclopaedia, we don't know many planets beyond 5 AU, and those that we do know are more massive than Jupiter. This is because the radial velocity changes a wide-orbit planet induces are small, and the time you need to observe the star is longer. In addition, small planets are harder to detect.

Inner-system Saturn-mass planets seem to be fairly common though.

If it's possible to have multiple-Jovian systems (e.g. Upsilon Andromedae) and multiple-Neptune systems (HD 69830), a multiple-Saturn system seems a reasonable possibility. HD 37124 has three planets around twice the mass of Saturn.

[MKruer]

I think they were referring to the rings, not just the size. In either case, its very probable that their would be multiple planets with rings around them. In fact all the large Jovian planets do, its just that Saturn?€™s rings are the best defined. However Saturn?€™s rings are not eternal. If I recall correctly the rings of Saturn were forms relatively recently in cosmological terms, something like in the last 100,000 yrs, and probably made by a collision between two moons.

[buggs_moran]

Even Earth had a ring system of a sort if the theory on moon formation was correct and it might again...

Ultimately, it makes Earth spin even slower than its new once-a-month rotation. Angular momentum then harasses the Moon again, this time by robbing it of energy. Thus begins the era when the Moon starts falling toward us.

Fortunately for humanity's fate, the Moon will break apart before it reaches 10,000 miles (16,000 kilometers) away because its silicate rocks are only half as dense as Earth's heavier materials.

Voil? ! Earth gets a ring even more glorious than Saturn's. Pencil it in around 3 billion years from now.

[Dollan]

The Earth may have had a ring much more recently than that. Check this out: http://www.science-frontiers.com/sf012/sf012p07.htm

That isn't the good scientific link that I once had, located somewhere in the depths of LiveScience.com, but that page seems to have gone away. I remember a similar article in an issue of Astronomy from the 1980's.

...John...

[ZZ-Cephei]

Has someone seen this?

http://www.extrasolar.eu/star.php?st=HD+24040
http://www.extrasolar.eu/star.php?st=HD+154345

These planets are still not confirmed, further investigations are needed but some interesting data have been drawn.
We should have got two hydrocarbons jovian planets.
The mass is bigger than Saturn (and perhaps HD 24040 b mat be a brown dwarf)...
But Saturn-mass planets in Saturn-orbits are still undetected...
Saurn mass planets are actually epistellar or in close orbits