Astronomers Spot Sun-Like Star Devouring a Planet, Giving Insight into Earth’s Fate
Astronomers have made a remarkable discovery after spotting a sun-like star devouring a planet. The event provides an insight into what will happen to Earth in around four billion years when our sun begins to expand, eventually swallowing up our planet.[0] The star in question was first seen by the Zwicky Transient Facility, an instrument based at Palomar Observatory in Southern California that scans the skies for cosmic events that change in brightness rapidly. Over the course of around 10 days, the star brightened by a factor of about 100.[1] The light shone for 100 days before fading away.[2]
The star was around 13,000 light-years away, and the event provides the first direct evidence of a dying star expanding to engulf one of its planets.[3] The devouring of a planet by an engorged star is likely to presage the ultimate fate of Mercury, Venus, and Earth when our sun begins its death throes in about five billion years.[3] The star was first picked up by the Zwicky Transient Facility, which studies the sky in optical and infrared wavelengths, looking for binary stars on such close orbits that one of them slurps material from the other, creating flares of light.
The star in question had initially been sought out because astronomers were looking for brilliant blasts from the remnants of sun-like stars, which make the star blaze thousands of times brighter than usual.[4] However, the team stumbled upon the discovery by accident when the star grew more than 100 times brighter in a little over a week some 12,000 lightyears away, near the eagle-shaped constellation Aquila in our galaxy.[5]
The brightening was evidence of dust forming around the star.[6] The dust indicates that the planet didn’t go down without a fight and that it pulled hot gas away from the puffy star’s surface as it spiraled toward its doom.[6] If the gas had dispersed into outer space, it would have undergone a cooling process and transformed into dust particles, similar to how water vapor transforms into snow.[6] As the star and planet collided, additional gas was ejected into space, resulting in an increased amount of visible dust that could be observed by both ground-based infrared observatories and NEOWISE.[6]
The star’s behavior is typical of what happens when a star runs out of hydrogen to fuse at its core. The star first collapses a bit on itself to kickstart the fusion of helium and then it expands, becoming a million times larger. The star has transformed into a red giant.[7] Red giants are expected to engulf their closest planets as they expand, but this had never been seen before.[8]
Stars undergo fusion of hydrogen atoms into helium throughout the majority of their lifespan. Once they have exhausted their hydrogen fuel, however, they begin fusing helium, leading to a massive increase in energy output that causes them to swell to hundreds or even thousands of times their original size, gobbling up their inner planets as they transform into huge stars called red giants.
The distinctive brightening pattern of the star allowed the researchers to detect the event, which is comparable to the eventual fate of our own sun.[9] When the sun runs out of hydrogen to fuse at its core, it will expand to engulf the other inner planets, and this system is a sort of preview of Earth’s fate.[1]
“I think there's something pretty remarkable about these results that speaks to the transience of our existence,” said co-author Ryan Lau.[9] After billions of years of existence, the end stages of our solar system will probably be marked by a brief flash lasting just a few months.[9] The discovery is exciting because it allows scientists to see a planet undergoing its fate in real time, which has never been seen before.
0. “Yes! Astronomers catch star eating its innermost planet” Big Think, 3 May. 2023, https://bigthink.com/starts-with-a-bang/star-eats-planet/
1. “We've seen a star devouring a planet for the first time” New Scientist, 3 May. 2023, https://www.newscientist.com/article/2371431-weve-seen-a-star-devouring-a-planet-for-the-first-time
2. “For the first time, scientists watched a dying star swallow a planet whole” Livescience.com, 4 May. 2023, https://www.livescience.com/space/exoplanets/for-the-first-time-scientists-watched-a-dying-star-swallow-a-planet-whole
3. “Astronomers witness star devouring planet: possible preview of the ultimate fate of Earth” EurekAlert, 3 May. 2023, https://www.eurekalert.org/news-releases/987978
4. “Star Caught Swallowing a Planet – Sky & Telescope” Sky & Telescope, 3 May. 2023, https://skyandtelescope.org/astronomy-news/star-caught-swallowing-a-planet/
5. “A star ate a planet, and astronomers saw it happen for the first time” The Washington Post, 3 May. 2023, https://www.washingtonpost.com/climate-environment/2023/05/03/dying-star-eats-planet-study
6. “Caught in the Act: Astronomers Detect a Star Devouring a Planet” NASA Jet Propulsion Laboratory, 3 May. 2023, https://www.jpl.nasa.gov/news/caught-in-the-act-astronomers-detect-a-star-devouring-a-planet
7. “Ten-day optical burst shows star eating giant planet, scientists say” The Register, 4 May. 2023, https://www.theregister.com/2023/05/04/star_eats_planet/
8. “For The First Time, A Star Has Been Caught Devouring Its Planet” IFLScience, 3 May. 2023, https://www.iflscience.com/for-the-first-time-a-star-has-been-caught-devouring-its-planet-68735
9. “Astronomers watch a preview of the destruction of the Earth” Digital Trends, 3 May. 2023, https://www.digitaltrends.com/space/star-destroying-exoplanet/
