How common are asteroid belts?

Question

Obviously, the Sol system has a lot of asteroids. Like. A lot. Billions. But, we also have eight planets, when most stars with known exoplanets only have one or two. That being said, are large amounts of asteroids common to most solar system or is this another way in which Sol deviates from the norm?

BQ: I know that it's really, really hard to conclusively decide whether or not a particular star has any planets at all, let alone their composition or anything else about them. But based on solar system formation models, how many terrestrial planets are each star expected to have, on average?

Anonymous · Accepted Answer

A few stars have been discovered with asteroid belts, such as Vega. Of course, asteroid belts are hard to detect. Usually, you have to use infrared telescopes such as Herschel or Spitzer. But asteroid belts are thought to be the leftovers from planet formation, and considering the number of planets that we're finding these days, it's likely that asteroid belts are pretty common throughout the galaxy and the universe in general.

? · Answer

We can't detect asteroids around other stars. They have too little mass to create a Doppler shift, and too small an area to significantly block their sun's light. So we have no idea how common asteroid belts are.

We also have too small a sample to predict the incidence of terrestrial planets. It's only very recently that we have developed observational techniques sensitive enough to detect terrestrial planets at all.

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How common are asteroid belts?

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