Life on our planet has existed for several billion years. Young stars occupy a privileged position in our search for life on other planets. After all, it is easier to compare the past and present than to think about the future. But research has shown that we should not discount old stars as carriers of habitable planets, even if they die; Even if death is not so good for life.

One factor that appears critical is the stellar wind. Our planet’s magnetic field protects us from a constant stream of particles from the Sun. The situation is much worse when the stars are young and slowly recovering. Studies of stars like the Sun and even older stars show that they tend to have variable magnetic field strength and complexity, which greatly affects the stellar wind.

As these sun-like stars age, catastrophic explosions become less likely, life around the objects becomes more likely, and even provides a better chance for advanced civilizations to develop.

So stars like the Sun or older are good up to a point. Our own star and many stars like it are destined to become red giants. When a star’s core runs out of hydrogen, it first contracts, ignites helium, and then expands. When the Sun swells, its outer layer is likely to extend into Earth’s orbit. Even though the plasma density is very low, we hypothesize that being inside a star is not good for life.

The red giant phase is also characterized by the release of strong stellar winds, and heat from the now massive star pushes the habitable zone further. This may be good news for the moons of the gas giants, but not so good for the rocky planets: Venus and Mercury will almost certainly be destroyed at this point, and at best Earth and Mars will be incinerated. So it’s not very hospitable to life, at least not anywhere.

Researchers also wondered what would happen next. Red giants shed their layers, leaving behind a compressed, degenerate core. We call this dead star a white dwarf. White dwarfs, with no stellar winds and great stability for billions of years, are a great place for life if the planets survive the red giant phase and life develops after the white dwarf.

Research shows that the transition from a normal star to a red giant to a white dwarf is too rapid for life to adapt, unless there is a way to shield and move the entire planet. Old stars and white dwarfs should be investigated as potential carriers of life, but it seems unlikely that life could continually exist on a world where the star changes and evolves. The new study was published in The Astrophysical Journal Letters.