According to “autopsies” of planets frizzled by white dwarfs:
In a study published on Thursday, researchers studied six white dwarfs whose strong gravitational pull had sucked in shredded remnants of planets and other rocky bodies that had been in orbit. This material, they found, was very much like that present in rocky planets such as Earth and Mars in our solar system.
Given that Earth harbors an abundance of life, the findings offer the latest tantalizing evidence that planets similarly capable of hosting life exist in large numbers beyond our solar system.
“The more we find commonalities between planets made in our solar system and those around other stars, the more the odds are enhanced that the Earth is not unusual,” said Edward Young, a geochemistry and cosmochemistry professor at the University of California, Los Angeles (UCLA), who helped lead the study published in the journal Science.
Will Dunham, “Planetary ‘autopsies’ indicate worlds like Earth common in the cosmos” at Reuters
In case you thought this field was “settled science”, see also: “Evolution” says we are alone
and
Once again, for the thousandth time, we are “closing in” on alien life