In several billion years, it will stop merging, shrink to a white dwarf, and give off only remnant heat. There he will sit, inactive and comatose.
But the Sun anchors the entire Solar System. What will happen to the Earth? To the rest of the planets? To the rest of the objects in the Solar System?
This illustration shows a white dwarf star extracting debris from shattered objects in a planetary system. Image credit: NASA, ESA, Joseph Olmsted (STScI)
Our Sun appears relatively placid during a human lifetime. He’s solidly on the main sequence now and reliably going about his business fusing hydrogen into helium. But this state will not last forever; stars do weird things as they get older.
Eventually, the Sun will age out of its fusion life and become a red giant. It will then shed its outer layers into a beautiful nebula. The nebula will dissipate after about 20,000 years, leaving only the dead core of our once-glorious Sun. Without the external pressure of the merger, gravity will take over and squash what’s left of the star into a ball of matter. degenerate the size of the Earth. It will be a white dwarf, a boiling cinder of inert carbon and oxygen that radiates residual heat for trillions of years, perhaps longer.
White dwarfs are one of those strange final states that some stars find themselves in after their fusion lifetime ends. But astronomers believe that almost all stars are home to planets. What happens to the planets around a star when it becomes a white dwarf?
Astronomers can’t see into the future, but they can look at existing white dwarfs and look for clues to the fate of their planets.
Even the distant Kuiper Belt might not escape the ravages of a dying Sun.
That’s what a team of researchers in Germany and the US did in their paper titled “Unusual abundances of planetary system material contaminating the white dwarf G238-44.” They examined observational data on the white dwarf from Hubble, the Keck Observatory, and FUSE, the Far Ultraviolet Spectroscopic Explorer. His paper has been accepted for publication by The Astrophysical Journal and is available on the preprint site arxiv.org.
Our Sun will eventually produce a nebula that will last for around 20,000 years. It is impossible to predict what that nebula will look like. Maybe it will look like this. This image is the Tarantula Nebula, as seen by the James Webb Space Telescope. Credit: NASA, ESA, CSA, STScI, Webb ERO production team.
G238-44 is about 86 light-years away and has a hydrogen-dominated atmosphere contaminated with other elements, including carbon, neon, oxygen, sulfur, and iron. Twenty-four years of Keck data show a steady and continuous accumulation of these materials from a circumstellar reservoir toward the white dwarf. The researchers also say they discovered “an anomalous abundance pattern and evidence for the presence of metallic iron.” Could iron and the other elements come from a single main body? Or are two bodies needed to explain the presence of all these materials?
The researchers say that if this metallic iron comes from a single parent body, that parent body is unlike anything in our own Solar System. “Within uncertainties, we can determine that the parent material is rich in nitrogen and likely contains a significant amount of metallic iron,” the authors write. “This mix is unlike any body in the known solar system.”
If it came from two separate bodies, they write, then one is made of iron-rich material similar to Mercury, and the other could be an icy Kuiper Belt object. These objects have distinct compositions and together provide “chemical evidence for rocky and icy bodies in an exoplanetary system,” the paper states.
The mix of elements and how they appear in a solar system is key to this work. Oxygen is versatile and is found everywhere in the solar system, and is a component of all objects. But carbon, nitrogen and iron are different. The authors describe them as “much more specialized”. Objects that form near the parent star have a higher abundance of Fe, while N only forms in significant amounts beyond the solar system frost line. “We do not expect objects that are high in Fe to also be high in N. G238-44 breaks this trend and is both high in Fe/O and N/O,” the authors write. “The proposed two-body model is capable of reproducing this unusual feature.”