We Are Weird? - No!

[Krupin]

Quote from the topic:

http://www.thescienceforum.com/viewt...=30966&start=0 :

The 'we' in this thread title refers to our solar system.

 

An article in New Scientist : 14 May 2011 page 47 (paper copy)

 

It reviews the results of extra-solar planet finding, with over 200 planets so far discovered in a little under 200 star systems. The surprise finding is that nothing like our solar system has yet been discovered.

 

Our solar system is atypical. We have a system with small rocky planets close to the sun, and large gas giants further out. All are in almost circular orbits, moving in a well behaved, stately way, around the sun. And of course, we have Earth in the liquid water belt, also in a beautiful, stable, almost circular orbit.

 

Other stellar systems have all kinds of different systems. Giant planets orbiting very close to their parent star are common. Wildly eccentic and elliptical orbits. Planets massively bigger than Jupiter. Every indication of violent interactions between bodies within those systems.

 

At first glance it seems that all this is true. But consider the system Gliese 581. We write the order of the values of orbital radii: 0.030, 0.041, 0.073, 0.146, 0.220, 0.758. Multiply this numbers by 23.65. Obtain a series of numbers: 0,71, 0,97; 1.73, 3.45, 5.20, 17.9. What is it?

 

Comparable to the orbital radius of planets in the solar system:

0.71 ; 0.97 ; 1.73 ; 3.45 ; 5.20 ; --- ; 17.9

0.72 ; 1.00 ; 1.52 ; ---- ; 5.20 ; 9.54 ; 19.1

As you can see, there is an obvious similarity, which confirms that planetary systems are created for one scenario.

Although over five hundred planets discovered so far, but there are the only 7 systems are multyplanetary enough (more 3 planet) for reliable analysis. There are : Gliese 581, Gliese 876, 55Cancri, Upsilon Andromedae A system, My Arae, HD10180, Kepler-11. And all of them have made in accordance with an universal principle (but not Bode-Titius's "Law"). More over, systems of moons of Saturn, Jupiter, Uranus have made in this way.

Note the following important fact. When comparing the solar system with a system Gliese 581 major satelites of the systems have coincided to each other. This is our general principle.

Let's draw up a comparative table of the six systems (left to right): Gliese 581, Solar, Saturn, Uranus, Jupiter, Gliese 876. Orbital radius of the largest satelites take equal to 1. This celestial bodies are: Gliese 581 d, Jupiter, Titan, Titania, Ganymede, Gliese 876 e. Consider the part of systems lying below the orbits of primary satelite. Obtain the table:

 

[Moontanman]

So far we don't have a big enough sample of planetary orbits to say what is typical if it is indeed possible to say what is typical. The reason the number of gas giants in orbit near their sun we have detected is so great is because they are the easiest to find. Newer techniques are slowly giving us more data but to say we know enough to say any planetary system is typical of all of them is just premature to say the least.

[maddog]

Some time has elapsed in this thread. Even so, I think I side with Moontanman on this as our sample size is still too small to

conclude much other than gas giants are common and that multiple star stellar systems being too unstable to have planets is

demonstrated to be fallacious.

 

Recently with Kepler 22-b was found a terrestrial-like planet surrounding a G-type star. Two thing about our sampling process

that is at best inconclusive - is that our sampling process captures all the planets surrounding a star and that terrestrial-like

planets must be rare. Neither are necessarily true by the data. By the very nature how Keplar data measure a complete picture

of a solar system by its light intensity. Only close planets are likely to create transits, farther out planets are very UNlikely

to transit. Only bigger gas giant-like planets attenuate the light enough.

 

Kepler 22-b changes that. Now the data says this planet is still 2.4 times bigger than earth, it's density still implies

terrestrial properties. As our baseline fills in a bit better, I think you find that Kepler satellite will get better at picking out

terrestrial size planets. With the current technology, we may still not know if we will ever be able to know how many planets

"typically" orbit a star.

 

maddog