Astronomers Discover A Star Devouring A Planet In Chilling Foreshadow Of What Awaits Earth
As our own Sun gets closer to its red giant phase in approximately 6 billion years, it will run out of fuel at its core. This is typically the most violent period in a star's life, as it throws out material from its outer layers in intense episodic bursts, according to NASA. When it reaches that point, the Sun will "puff up" so much that it will devour some of the inner rocky planets. It is this end-of-life event that a group of researchers have documented in a new research paper published in the journal Nature.
The group of astronomers discovered the event, once called ZTF SLRN-2020, utilizing multiple ground-based observatories and NASA's Near-Earth Object Wide Field Infrared Survey Explorer (NEOWISE). The planet being swallowed up by the aging red giant star was about the size of Jupiter with an orbit that was closer than that of Mercury to our own Sun.
During the observations, the astronomers documented the outer atmosphere of the star expanding and surrounding the planet. As drag from the atmosphere slowed the planet's orbit down, its orbit began to shrink and eventually led to the planet burning up like a meteor entering the Earth's atmosphere. This transfer of energy caused the star to temporarily swell in size and glow a hundred times brighter, before eventually returning to the size and brightness before the planet was gobbled up.
"Very few things in the universe brighten in infrared light and then brighten in optical light at different times," explained Kishalay De, an astronomer at the Massachusetts Institute of Technology in Cambridge and the study's lead author. "So the fact that NEOWISE saw the star brighten a year before the optical eruption was critical to figuring out what this event was."
As far as Earth's future goes, astronomer Dimitri Veras at the University of Warwick is not certain, as he explains, "I am confident that the Sun will swallow Mercury and Venus, and not Mars. But the fate of the Earth -- which resides in between -- is less clear."
The group of researchers says it is a discovery such as this one that make it worthwhile to gather observations of the entire sky and archive them, because astronomers and scientists are not certain of all the events being captured. Joe Masiero, Deputy Principal Investigator for NEOWISE at IPAC at Caltech, added, "With the NEOWISE archive, we can look back in time. We can find hidden treasures or learn something about an object that no other observatory can tell us."
