Summary of the article by ScienceAlert reporter Michelle Starr:
The hunt is on for a second Earth, somewhere out there in the Milky Way galaxy, but a newly discovered world is not quite the thing.
It comes in at around 1.9 times the mass of Earth, orbiting its star at around twice Earth’s distance from the Sun… but that star is a white dwarf, which means any life that might have been on the exoplanet was probably obliterated before or during the star’s red giant death throes.
But the discovery is an exciting one, nevertheless: it’s like getting a sneak peek at the future of the Solar System, and the fate of Earth, once the Sun dies and completes its own evolution into a white dwarf.
And the work, led by astronomer Keming Zhang of the University of California, shows the potential for the way it was discovered – a phenomenon known as microlensing – to locate other hard-to-find Earth-like worlds elsewhere in the galaxy.
Eventually, the star will eject its outer material completely, and the core will collapse under gravity to form a dense object, its bright light not generated by fusion, but the residual heat of its collapse process. That hot core is the white dwarf, and it will take trillions of years to cool to complete darkness.
We don’t know what this will mean for our planet. Its destruction is possible. But this new discovery of an Earth-like world orbiting a white dwarf suggests that survival is also an option.
“The simplest explanation is that the planet survived through the red giant host star,” Zhang told ScienceAlert.
I wouldn’t have expected the planet to survive the red giant phase, the surface is probably altered completely or maybe it stripped away all the gas from a smaller gas giant, but it’s still really interesting to know survival can happen.
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Summary of the article by ScienceAlert reporter Michelle Starr:
The hunt is on for a second Earth, somewhere out there in the Milky Way galaxy, but a newly discovered world is not quite the thing.
It comes in at around 1.9 times the mass of Earth, orbiting its star at around twice Earth’s distance from the Sun… but that star is a white dwarf, which means any life that might have been on the exoplanet was probably obliterated before or during the star’s red giant death throes.
But the discovery is an exciting one, nevertheless: it’s like getting a sneak peek at the future of the Solar System, and the fate of Earth, once the Sun dies and completes its own evolution into a white dwarf.
And the work, led by astronomer Keming Zhang of the University of California, shows the potential for the way it was discovered – a phenomenon known as microlensing – to locate other hard-to-find Earth-like worlds elsewhere in the galaxy.
White dwarfs are what stars like the Sun turn into when they die. They run out of hydrogen fuel to fuse in their cores and become less stable, puffing up to an enormous size. That’s the [red giant phase](https://www.sciencealert.com/bubbles-75x-larger-than-our-sun-are-boiling-on-this-distant-stars-surface).
Eventually, the star will eject its outer material completely, and the core will collapse under gravity to form a dense object, its bright light not generated by fusion, but the residual heat of its collapse process. That hot core is the white dwarf, and it will take trillions of years to cool to complete darkness.
The red giant phase is pretty crazy. The star’s outer atmosphere can expand to hundreds of times its initial size; some projections of the Sun’s future – due to start becoming a red giant [in about 5 billion years or so](https://www.sciencealert.com/scientists-figured-out-when-and-how-our-sun-will-die-and-it-will-be-epic) – predict it could grow as large as out to the orbit of [Mars](https://sciencealert.com/mars), engulfing [Mercury](https://sciencealert.com/mercury), [Venus](https://sciencealert.com/venus), and Earth in the process.
We don’t know what this will mean for our planet. Its destruction is possible. But this new discovery of an Earth-like world orbiting a white dwarf suggests that survival is also an option.
“The simplest explanation is that the planet survived through the red giant host star,” Zhang told ScienceAlert.
Read the peer-reviewed paper here: [https://doi.org/10.1038/s41550-024-02375-9](https://doi.org/10.1038/s41550-024-02375-9)
I wouldn’t have expected the planet to survive the red giant phase, the surface is probably altered completely or maybe it stripped away all the gas from a smaller gas giant, but it’s still really interesting to know survival can happen.