Astronomers recently uncovered a groundbreaking revelation about a remote planet, surpassing Jupiter in size and scorching in temperature, suggesting its inevitable path towards its host star, resulting in its obliteration. This catastrophic event is expected to happen in the near future, given the immense expanse of cosmic time.
Lead scientist Pietro Leonardi, from the University of Padova, clarified, “Our calculations now show that the collision between WASP-12b and its star is expected to happen in just 3 million years, a significantly shorter timeframe compared to previous estimates.” Despite seeming long to humans, in the grand scheme of the universe where stars like the sun can last around 10 billion years, this is an incredibly brief period.
WASP-12b’s perilous proximity
WASP-12b, known as the ill-fated planet, revolves around its yellow dwarf star at an extremely close distance, completing an orbit in just one Earth day. This proximity classifies WASP-12b as an “ultra-hot Jupiter” planet, appropriately named because of the intense radiation it receives from its star, leading to surface temperatures reaching approximately 4,000 degrees Fahrenheit (2,210 degrees Celsius).
Nevertheless, what sets this ill-fated world apart as an extreme exoplanet, unlike anything in our solar system, is not just its scorching temperatures. The intense gravitational pull felt by WASP-12b, positioned a mere 2.1 million miles from its star, creates strong tidal forces that warp the planet into an oblong shape.
Moreover, this gravitational effect leads to material being stripped away from WASP-12b, forming a ring of substance around the planet’s sun.
Discovered in 2008, WASP-12b was once known as the hottest planet, a title later taken by another planet called Kelt-9b in 2018. WASP-12b also held the distinction of being the nearest planet to its star, although this record has now been claimed by K2-137b, located just over half a million miles from its red dwarf star, situated approximately 322 light-years away from Earth.
Despite the abundance of hot Jupiter exoplanets discovered since the mid-1990s, WASP-12b has always stood out from the rest.
Previously, variations in its orbital period were attributed to factors such as its position relative to Earth and a gradual shift in its orbit.
To investigate these variations, Leonardi and his team analyzed 28 observations of WASP-12b as it passed in front of its parent star. These observations were conducted in collaboration with the Asiago Search for Transit Timing Variations of Exoplanets (TASTE) project and spanned a period of 12 years from 2010 to 2022. The data was collected by the Asiago Observatory in Italy.
The study not only revealed that WASP-12b is on a collision course in approximately 3 million years due to tidal dissipation, but it also suggested heightened activity in the planet’s yellow star. During periods of increased activity, stars exhibit more sunspots, which are dark patches on their surface, and experience more intense outbursts of charged particles known as plasma. As a result, the team may have observed WASP-12b enduring an exceptionally violent onslaught from its star.
One surprising finding from the team’s analysis was evidence indicating that the dwarf star may have already reached the end of its main-sequence lifespan, during which stars burn hydrogen in their cores.
“For a star like WASP-12, which has a mass and width approximately 1.5 times that of the sun and falls within the low to intermediate mass range, the cessation of core-hydrogen burning marks the beginning of the ‘sub-giant phase.’ This phase is characterized by hydrogen burning in the star’s outer layers,” explained Leonardi.
Leonardi explained that based on the tidal dissipation theory, the observed dissipation level in the system is higher than expected for a main-sequence star. If the star had already moved into the sub-giant phase, this difference could be easily clarified. To examine this theory, the team used high-resolution optical spectra from HARPS-N to determine the stellar parameters and deduce its evolutionary stage.
Nevertheless, the findings show that the star is still in the main sequence and has not progressed to the sub-giant phase.
As a result, the team needs to delve deeper into how a main-sequence dwarf star can induce rapid tidal dissipation.
In approximately 3 million years, the collision between WASP-12b and its star will result in noticeable changes that can be observed from Earth, assuming intelligent life still exists on our planet.
According to Leonardi, the collision will first manifest as a significant increase in luminosity, causing the star to become hundreds of times brighter than its current state. Although this surge in brightness will be temporary, future generations may have the opportunity to witness and study this extraordinary event.
Leonardi suggests that the fate of WASP-12b could have implications for other ultra-hot Jupiters, potentially indicating that they too are on a collision course with their respective stars.
To gain a better understanding of the phenomenon, Leonardi is collaborating with the team working on the European Space Agency (ESA) mission known as CHaracterising ExOPlanet Satellite (CHEOPS). Their aim is to determine the rate of orbital decay for other hot Jupiters.
“This research serves as the initial phase of a comprehensive investigation into orbital decay,” concluded Leonardi.
For more information, the team’s research can be accessed on the arXiv paper repository.
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