Lisa Kaltenegger

Professor of Astronomy, Director of the Carl Sagan Institute

Lisa Kaltenegger, who was not involved in the study, is director of Cornell University’s Carl Sagan Institute, a professor of astrophysics, one of the world’s leading experts on exoplanets and an author of a 2018 paper on habitable worlds around white dwarfs. She says the discovery of a planetesimal sheds light on how planets form around white dwarf stars and that with the right conditions, these planets could foster life.

Kaltenegger says:

"If an Earth-like planet around a white dwarf could form and then get water delivered after the initial hot stage of the star’s evolution, such a planet could stay habitable for about 7 billion years - longer than humans have existed on Earth.

"This paper puts the first puzzle piece in place to determine how planets could form around young white dwarfs from planetesimals. After the white dwarf cools down further, such a planet could maintain balmy conditions for billions of years.

"If a planet around a white dwarf forms, one key question is how it could get water delivered, after the initial incredibly hot stage of star’s evolution, where it would boil off. Then, with liquid water on the surface and a balmy environment for billions of years, life could potentially get started all over again."