Prepare to be amazed by the existence of exoplanet 8 Ursae Minoris b! Against all odds, this planet defies the laws of physics. It orbits its host star at a distance that should have been engulfed by the star itself. But somehow, 8 Ursae Minoris b has managed to survive.
Scientists have proposed a few explanations, but none of them seem very likely. One theory suggests that the planet’s survival is due to its host star being distracted by swallowing a white dwarf instead.
Discovering the Unbelievable
The discovery of 8 Ursae Minoris b was made using the radial velocity method, which detects changes in a star’s light caused by the gravitational pull of orbiting planets. This method allows us to estimate the minimum mass of the planet, but it could potentially be even larger.
At a minimum, we know that 8 Ursae Minoris b is a massive planet, over 1.6 times the mass of Jupiter. It also has a close proximity to its host star, completing an orbit in just 93 days, at a distance of half an Astronomical Unit (AU) from the star.
There are even hints of a second body orbiting the star at a distance of at least five AU, although the evidence is currently weak. This second body could play a significant role in shaping the system.
But what truly baffles scientists is the star at the center of this system.
A Stellar Mystery
8 Ursae Minoris, the star, is older and more massive than our Sun. It has already gone through the phase where it expanded due to hydrogen burning, and now it burns helium as a hotter, more compact star.
Here’s the problem: based on its mass, the star should have grown to a size that would have engulfed the planet’s orbit. Planets cannot survive within the envelope of a star. Calculations show that they would quickly spiral towards the star’s core due to friction. Observations of stars similar to 8 Ursae Minoris have not revealed any close-orbiting planets, supporting these calculations.
So why is 8 Ursae Minoris b still there? It’s a mystery that continues to puzzle scientists.
In a remarkable breakthrough, astronomers have announced the discovery of an “impossible planet” that challenges current scientific understanding of planetary formation in the universe.
Kelt-9b, which orbits its star once every 36 hours, is the hottest planet ever observed. With a temperature of 4,600 degrees Celsius, the exoplanet is even hotter than some stars.
One of the peculiarities of Kelt-9b is that it is 13 times closer to its star than any other planet in its star system. Furthermore, the exoplanet is much larger and more massive than similarly hot planets. The combination of these unique characteristics make Kelt-9b the first known example of an “impossible planet,” defined by astrophysicists as a planet which cannot be explained under existing theoretical models of planetary formation and evolution.
The discovery of Kelt-9b has cast doubt on the principle of ‘hot-start’ formation, the most widely held model of how planets form and evolve. In this model, planets form in a circumstellar disc of gas and dust that gradually accretes until it reaches a large enough size, and is then heated by the star, releasing energy and inflating the planets.
Kelt-9b appears to be too close to its star to fit this model. Scientists are now looking for alternative models that can explain the phenomena.
The discovery of Kelt-9b shows that our understanding of planetary formation still has significant room for improvement. With further research, we may eventually be able to piece together a more complete picture of how and why planetary systems take shape.
