Polluted Old Stars Suggest Earth-like Worlds May Be Common

Most suns such as our own end their lives as white dwarfs. If youve done high school chem you might remember "signatures" in the spectral analysis can spot the elements in the sample youve put under the bunsen. A similar method can be used to spot pollutents from an external source in white dwarfs. The old explanation was the white dwarfs had been around the milky way a few times and been contaminated, but it doesnt fit any more.

Farihi and his colleagues looked at the positions of these white dwarfs within the Milky Way and estimated whether the impurities they saw in the stars' atmospheres could be explained by sweeping up the interstellar medium.

"And the answer is a resounding 'No, it doesn't make sense,'" Farihi said

Farhiri took the signatures from 1 million cosmic objects and

They found that the types of metals seen in the stellar atmospheres, such as silicon, magnesium and iron, suggest a rocky origin. The exact source of the rocky debris isn't known, but Farihi says there are two possibilities: the debris could come from an asteroid belt similar to our own, which essential represents a planet that didn't form, or the pieces of a shattered planet.

at least 3 percent and possibly as much as 20 percent of all white dwarfs are contaminated by rocky material

This suggests a similar percentage of suns like our own host planetary systems.

Interestingly, there are also indications that some of the rocky material polluting the white dwarfs contained water

Interesting that this article has found two ingredients for life, planets and water.
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There has been a number of articles out recently suggesting similar conclusions from new research.

Combining the results of a search for extrasolar planets in our galaxy and a method for calculating the likelihood that extrasolar planets exist, only about 15 percent of the stars in the Milky Way likely host systems of planets like our own, one astronomer said here today at the 215th meeting of the American Astronomical Society

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The above speculation arose after some microFUN gravitational microlensing which is particularly good at spotting giant planets in the outer reaches of the galaxy.

Another article
Billions of habitable planets