NASA’s James Webb Space Telescope (JWST) has overturned long-held assumptions about how aging stars consume their planets, providing a clearer understanding of the fate that may await planetary systems like our own.
Observations indicate that instead of dramatic engulfment, a planet slowly spiraled inward over time before meeting its fiery end.
Data gathered by researchers from NSF’s NOIRLab, using Webb’s mid- and near-infrared instruments, highlights this novel phenomenon and challenges previous theories regarding planetary engulfment by stars.
The star at the center of this event is located approximately 12,000 light-years away in the Milky Way galaxy and initially caught the attention of astronomers in 2020 due to a flash of visible light labeled ZTF SLRN-2020.
Earlier infrared data from NASA’s NEOWISE mission had revealed a significant brightening signal, suggesting a buildup of dust around the star.
Subsequent investigations in 2023 led researchers to believe that this star was transitioning into a red giant.
However, observations made with Webb’s Mid-Infrared Instrument (MIRI) offered a different perspective.
The MIRI’s capability to isolate faint emissions in crowded star fields demonstrated that the star was not nearly as luminous as a typical red giant should be, indicating it never expanded enough to engulf a planet in one violent swoop.
“Because this is such a novel event, we didn’t quite know what to expect when we decided to point this telescope in its direction,” said Ryan Lau.
“With its high-resolution look in the infrared, we are learning valuable insights about the final fates of planetary systems, possibly including our own.”
The planet in question, estimated to be roughly the size of Jupiter, orbited its host star at a distance significantly closer than Mercury’s orbit around the Sun.
Over millions of years, the planet spiraled inward and eventually began to brush against the star’s outer atmosphere.
This interaction triggered a runaway effect, accelerating the planet’s descent as it drew closer to the star.
“The planet, as it’s falling in, started to sort of smear around the star,” explained Morgan MacLeod.
This violent process would have expelled gas from the star’s surface, which cooled and formed a dust halo that continued to glow in the infrared long after the planet’s demise.
Webb’s Near-Infrared Spectrograph (NIRSpec) further illuminated the aftermath of this occurrence.
In addition to the expected cool dust cloud, it unveiled a surprising discovery: a hot, molecular gas disk enveloping the star.
This accretion disk, which contains carbon monoxide and other compounds, closely resembles regions where new planets are typically formed.
“With such a transformative telescope like Webb, it was hard for me to have any expectations of what we’d find in the immediate surroundings of the star,” commented Colette Salyk.
“I will say, I could not have expected seeing what has the characteristics of a planet-forming region, even though planets are not forming here, in the aftermath of an engulfment.”
The leftover material reveals significant information about what transpires after a planet’s obliteration by a star.
Researchers are now delving into questions regarding how the interaction may have altered the star’s outer layers or impacted nearby planetary debris.
This extraordinary event was documented under Webb’s Guaranteed Time Observation program 1240, recognized as one of the first Target of Opportunity programs ever conducted by the telescope.
These programs are designed to capture rare astronomical occurrences, such as stellar explosions or drastic system changes, even though scientists cannot pinpoint their exact timing or locations.
“This is truly the precipice of studying these events. This is the only one we’ve observed in action, and this is the best detection of the aftermath after things have settled back down,” enthused Lau.
He added, “We hope this is just the start of our sample.”
The fate of planet Earth concerning the Sun’s evolution is a topic of much contention amongst scientists.
In approximately five to seven billion years, the Sun will exhaust its hydrogen fuel, causing its core to contract and heat while its outer layers expand.
This transformation will result in the Sun swelling into a red giant, potentially swallowing Mercury and Venus in the process.
Earth’s position places it at risk, sitting right on the edge of the danger zone.
Some researchers speculate that the Sun could completely engulf Earth, while others believe Earth may narrowly escape, pushed outward as the Sun loses mass.
Regardless of the scenario, the outcome remains dire.
Even if Earth avoids being swallowed, it cannot withstand the intense heat, leading to the boiling away of oceans, the evaporation of the atmosphere, and the incineration of the surface.
Eventually, the Sun will shed its outer layers and collapse into a dense white dwarf, leaving behind a frozen, lifeless husk of Earth orbiting a dim, burnt-out star, devoid of fire, light, or life.
Looking ahead, events similar to ZTF SLRN-2020 are anticipated to be discovered, thanks to advanced observatories like the upcoming Vera C. Rubin Observatory and NASA’s Nancy Grace Roman Space Telescope.
These instruments will monitor the sky repeatedly, enabling scientists to track sudden changes and broaden our understanding of interactions between stars and planets as they reach their concluding phases.
The complete study detailing this significant research has been published in the journal The Astrophysical Journal.
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