Planet formation should be common shouldn't it?

[bdewoody]

Any fourth or fifth generation star that forms in a stellar nursery or from a sifficiently dense cloud of dust should end up with it's own left over material that should accrete into several planets of various sizes and types. At least that's the implication I get from some of the programs I've seen lately on various Discovery Channels. I feel that as we gain ground in our ability to determine the presence of planets around other stars the vast majority of them will have planetary systems. I'm wondering what conditions would have to be present for a star to form without planets circling it.

On the other hand for a rocky planet to be able to foster life besides being big enough for tectonic plates to free up carbon dioxide won't it also have to have a moon similar in size ratio as our earth and moon? Much has been made of the moons stabilizing effect on the earth but not much is mentioned about moons when discussing whether other planets can support life.

 

[MeteorWayne]

Yes, in fact the latest data indicates that planet formation IS quite common.

When the Kepler results start coming in a few months from now, the case should be nailed down.

 

[michaelmozina]

Yes, in fact the latest data indicates that planet formation IS quite common.

When the Kepler results start coming in a few months from now, the case should be nailed down.

It seems to me that it's likely that most suns have planets just like our own sun. Since our solar system has planets, IMO the onus of responsibility falls to the one claiming that any solar systems exist without planets.

 

[ZenGalacticore]

I always thought they are common, long before we had any data. But as Wayne indicated, all the great data that we've acquired in the last decade or so tells us that planetary systems-at least around G and K class solitary main sequence stars and maybe even binaries- are most likely the rule, rather than the exception.

With the over 250 exo-planets we've discovered so far, as well as proto-planetary discs around stars as close to us as Epsilon Eridani, the odds are looking good for billions of planetary systems. And since the Sun is a typical G-2 class main-sequence solitary yellow star, and there are at least 5 or so billion similar stars in our Galaxy, then systems very much like ours almost certainly exist, billions of them.

I've read that we estimate that around 7% of the stars in our Galaxy are G class solitaries. (Ranging from G-2s like Sol, to G-8s, like Tau Ceti.) But apparently, we can't seem to get the ball-park figure for the estimated number of total stars in our Galaxy. Twenty or so years ago the estimate was upwards of 400 billion. A decade ago it went down to 200 billion, and now they estimate around 100 billion. :?

[edited for 'their' and 'there'] Jeez...

 

[SpaceTas]

400+ exoplanets and counting.

>10% sun like (lone, F G K main sequence) stars have a planetary system

Many stars have multiple planets (the fraction increases as we search longer and with improved instruments/methods).
Still really haven't been able to search for solar system analog's (1 or 2 systems with giants in right place known)

 

[ZenGalacticore]

>10% sun like (lone, F G K main sequence) stars have a planetary system

Really? How do you know? Is that based on the Drake Equation? Conservative estimates are fine by me but, I'd bet mule dung to Navy beans that most solitary G and K class stars have planetary companions.

Why do I think this, you may be asking? Because our Sun is one solitary G-2 class star. And there is bound to be more than a mere 10% chance of such stars having a similar "excess" of debris orbiting the gaseous nebula that coelesced into a variably averaging unique diversity of planets. And there are AT LEAST 5 billion sun-like yellow stars alone, if not a score of billion.

 

[bdewoody]

Also, assuming we can determine the approximate age of a star, those that are about the same age as our sun should get the highest priority when looking for earthlike planets. I'm basically ruling out stars that are more than forty thousand LY away. That distance should probably be even closer as it is doubtful we will ever travel more than a few hundred LY even in a one way colony ship.