Astronomers have identified for the first time a planet headed for what could be a collision with its star. The possible collision could provide an idea of how Earth might end up one day.
A team of researchers says the doomed exoplanet Kepler-1658b may help shed light on how worlds end as their stars age.
Kepler-1658b, which is 2,600 light-years from Earth, is a type of planet called a hot Jupiter, according to Science Alert.
How soon do astronomers estimate the collision between Kepler-1658b and its star?
Although similar in size to Jupiter, the planet orbits its host star at one-eighth the distance from the Sun to Mercury, making it much hotter than the gas giant in our Solar System.
Kepler-1658b’s orbit around its host star lasts less than three days and shortens by about 131 milliseconds per year, according to the study.
“If it continues to move towards its star at the observed rate, the planet will collide with the star in less than three million years. This is the first time we have observed direct evidence of a planet moving toward its evolved star,” said Shreyas Vissapragada, a postdoctoral fellow at the Harvard-Smithsonian Center for Astrophysics and lead author of the study.
The planet’s orbit is shortened by the ocean-like tide
An evolved star enters the “subgiant” phase of the stellar life cycle when it begins to expand and become brighter.
Kepler-1658b’s orbit is shortened by the tides, in a process similar to how Earth’s oceans rise and fall each day. This gravitational force can work both ways. For example, the Moon is very slowly moving away from the Earth.
Could Earth be headed for a similar trajectory?
“Death by stars is a fate believed to await many worlds and could also spell the end of Earth billions of years from now as our Sun ages,” the US Center for Astrophysics said.
Vissapragada stated that “in about five billion years, the Sun will evolve into a red giant star,” and “the fate of the Earth is somewhat unclear.”
Kepler-1658b, a reflective and hotter planet
Kepler-1658b was the first exoplanet ever observed by the Kepler Space Telescope, launched in 2009. However, it took nearly a decade of work before the planet’s existence was confirmed in 2019.
Over the course of 13 years, astronomers were able to observe the slow but steady change in the planet’s orbit as it transited in front of its host star. This was previously thought to be because it is a particularly reflective planet, he said.
But researchers now believe the planet is much hotter than expected, possibly because of the same forces pushing it toward its star.
The researchers’ study was published in The Astrophysical Journal Letters.