A team of scientists, led by the University of Leicester, may have unraveled the mystery behind an extraordinarily powerful stellar flare. This flare, estimated to be a trillion times stronger than the largest solar flares, is believed to be caused by a massive young planet engulfed in a scorching sea of raw materials swirling around it.
In a groundbreaking study published in the Monthly Notices of the Royal Astronomical Society, the researchers propose that a planet approximately ten times larger than Jupiter is experiencing “extreme evaporation” in close proximity to its nascent star. This intense evaporation process strips material from the planet and hurls it onto the star, resulting in the remarkable flare.
The scientists specifically focused on a protostar named FU Ori, positioned 1,200 light years away from our own solar system. This celestial object exhibited a substantial increase in brightness 85 years ago and has not yet returned to its expected luminosity, captivating the attention of the researchers.
By studying the statistics of similar flares occurring in developing solar systems, the team concludes that such planet elimination events could potentially be observed up to a dozen times in each system.
The findings of this study shed new light on the mechanisms behind powerful stellar flares and provide valuable insights into the processes occurring during the early stages of planetary formation.
Astronomers have long speculated about the cause behind the increased luminosity of the protostar FU Ori, attributing it to a greater influx of material from a protoplanetary disk—a cloud of gas and dust. However, the exact mechanisms involved in this phenomenon have remained enigmatic.
Professor Sergei Nayakshin, the lead author of the study and affiliated with the University of Leicester School of Physics and Astronomy, remarked, “While previous observations hinted at the presence of a young massive planet in close proximity to this star, various hypotheses were proposed to explain how the planet could trigger such a flare, but none seemed to fit the details. Our research has unveiled a novel process, which we refer to as a ‘disk inferno’ caused by young planets.”
According to Nayakshin, these disks not only supply growing stars with additional material but also nurture the formation of planets. The team’s discovery introduces a new mechanism through which young planets can induce powerful flares in the protoplanetary disk surrounding their host star.
By unraveling the intricacies of this “disk inferno,” scientists hope to gain a deeper understanding of the dynamics governing the early stages of planet formation and the interactions between young planets and their surrounding environments.
The team of researchers led by the University of Leicester conducted a simulation to better understand the phenomenon occurring in FU Ori. Their simulation focused on a gas giant planet that formed at a considerable distance from the central star through a process called gravitational instability. In this scenario, a massive disk surrounding the star fragments, giving rise to enormous clumps that are more massive than Jupiter but less dense.
The simulation demonstrated the rapid inward migration of this planetary seed towards its host star, driven by the star’s gravitational attraction. As the planet approaches a distance equivalent to one-tenth of the Earth-Sun distance, the surrounding material becomes incredibly hot, causing the outer layers of the planet’s atmosphere to ignite. This ignited planet then becomes a significant source of fresh material, fueling the growth of the star and causing it to emit a brighter shine.
Dr. Vardan Elbakyan, a co-author of the study also affiliated with the University of Leicester, emphasized that FU Ori was the first star observed undergoing such a flare. However, several dozen similar flares have been identified in other young stars within our region of the Milky Way. Although FU Ori events are extraordinary compared to typical young stars, the duration and observability of these events have led observers to conclude that most emerging solar systems experience similar flares approximately a dozen times while their protoplanetary disks are still present.
This research provides valuable insights into the nature of these extreme flares, allowing astronomers to broaden their understanding of the common processes occurring during the formation of solar systems.
Professor Nayakshin further remarks, “Should our model prove to be accurate, it would have significant implications for our comprehension of star and planet formation. Protoplanetary disks have conventionally been regarded as tranquil environments nurturing the birth of planets. However, our findings suggest that these so-called nurseries are, in fact, exceedingly turbulent and tumultuous, where a considerable number—potentially the majority—of young planets meet their demise, being engulfed and devoured by their host stars.”
“It is imperative now to investigate whether this scenario can account for the observed flaring behavior in other stars as well.”
In light of this study’s outcomes, scientists recognize the importance of examining whether similar mechanisms are responsible for the flaring phenomena observed in other stars. This investigation will contribute to furthering our understanding of the complex interplay between planets and their nascent stars during the early stages of stellar and planetary formation.
Source: University of Leicester