Can life bloom around a dead star? New research published in the Monthly Notices of the Royal Astronomical Society is encouraging.
A group of astronomers have calculated how the intensity of the solar wind will develop over the next 5 billion years. Until the star turns into a huge red giant. Scientists have found that by that time the solar wind will become so strong that it will almost completely destroy the protective magnetic field of the Earth. Because of this, most of the planet’s atmosphere will be in space, and with it, all remaining protection from sharp stellar radiation will disappear.
According to the authors, any organisms on Earth that manage to survive to this point will quickly die out.
Billions of years from now, the Sun (like all stars in the Universe) will eventually run out of hydrogen, which fuels nuclear reactions in its core. Without this fuel, the core of the Sun will begin to contract under the influence of its own gravity, and the outer layers of the star will begin to expand. Eventually, the Sun will turn into a red giant.
As the sun’s outer atmosphere expands, it will burn planets in its path. According to NASA, Mercury and Venus will almost certainly be destroyed – perhaps the same will happen on Earth.
After about a billion years of expansion, the Sun will turn into a white dwarf before extinguishing completely.
If the Earth manages to survive the transformation of the star into a red giant, the planet will remain in a solar system that will be very different from the current one. According to NASA, when the Sun’s core contracts, its gravitational pull towards the planets diminishes. As a result, all planets that are not absorbed drift about twice as far from the Sun as they do today. At the same time, the radiation from the red giant will also be much more intense than it is now.
The authors of the new study wanted to know: how intense will this radiation be and can the Earth’s magnetosphere survive the onslaught? In their work, the researchers modeled winds from 11 different types of stars with masses ranging from one to seven times the mass of the Sun. The researchers found that as the sun’s diameter increases towards the end of its life, the speed and density of the solar wind will fluctuate wildly, alternately expanding and contracting the magnetic fields of any nearby planets.
Ultimately, however, in the models, the magnetosphere of each planet was always “suppressed” by the force of the wind, the authors write in the study. According to scientists, the only way for a planet to maintain its magnetic field throughout the entire process of stellar evolution is if this planet has a magnetic field 100 times stronger than that of Jupiter today, or more than 1000 times stronger than that of Earth.
In other words, it is extremely unlikely that life on any planet will be able to survive the death of its star – but new life can arise from the ashes of the old, as soon as the Sun shrinks and the stellar wind dies down.