A team of mostly US-based researchers has discovered a planet, Kepler-1658b, that is spiraling towards a catastrophic collision with its aging sun for the first time. This discovery may provide insight into how Earth might end in the future.
In a new study published on Monday, the researchers stated that they hope the doomed exoplanet can help shed light on how worlds die as their stars get older. Kepler-1658b is located 2,600 light-years away from Earth and is known as a “hot Jupiter” planet.
An artist’s concept of the Kepler-1658 systeм. Kepler-1658Ƅ, orƄiting with a period of just 3.8 days, was the first exoplanet candidate discoʋered Ƅy Kepler. Credit: Gabriel Perez Diaz/Instituto de Astrofísica de Canarias
Kepler-1658b, despite being similar in size to Jupiter, orbits its host star at an eighth of the distance between our Sun and Mercury, making it much hotter than the gas giant in our own Solar System. The planet’s orbit around its host star takes less than three days, and it is getting shorter by around 131 milliseconds per year, according to the study published in The Astrophysical Journal Letters.
If the planet continues spiraling towards its star at the observed rate, it will collide with the star in less than three million years. This is the first time that direct evidence of a planet spiraling towards its evolved star has been observed, according to Shreyas Vissapragada, a postdoc at the Harvard-Smithsonian Center for Astrophysics and the study’s lead author.
An evolved star has entered the “subgiant” phase of the stellar life cycle, during which it expands and becomes brighter. Kepler-1658b’s orbit is being shortened by the tides, similar to how Earth’s oceans rise and fall every day. This gravitational push-and-pull effect can work both ways, for example, the Moon is very slowly spiraling away from Earth.
Earth’s ‘ultiмate adios’?
According to the Center for Astrophysics, a fate thought to await many worlds, including Earth, is death-by-star, which could be the Earth’s ultimate adios billions of years from now as our Sun grows older. Vissapragada said that “in five billion years or so, the Sun will evolve into a red giant star.”
While the tidally-driven processes seen on Kepler-1658b will drive the decay of the Earth’s orbit towards the Sun, that effect could be counterbalanced by the Sun losing mass. Therefore, the ultimate fate of the Earth is somewhat unclear.
Kepler-1658b was the first exoplanet ever observed by the Kepler space telescope, which launched in 2009. However, it took nearly a decade of work before the planet’s existence was confirmed in 2019. Over 13 years, astronomers were able to observe the slow but steady change in the planet’s orbit as it crossed the face of its host star.
One big surprise was that the planet itself is quite bright, according to Vissapragada. Previously, it had been thought that this was because it is a particularly reflective planet. But now, the researchers believe that the planet itself is far hotter than anticipated, possibly due to the same forces that are driving it towards its star.
Source: phys.org
