Welcome To Janssen, The ‘Hell Planet’ Of Lava And Diamonds Where A Year Lasts 18 Hours
There is a planet in the night sky that orbits its star in 18 hours, has a huge ocean of lava and a core made of diamonds.
Welcome to 55 Cancri e—better known as the planet Janssen—whose extreme orbit is revealed by new research published in Nature Astronomy.
An exoplanet (one that orbits a star other than our Sun) between the size of Earth and Neptune, Copernicus is 41 light-years away from us in the constellation of Cancer, “the crab.” There are actually two stars in this system—something that sounds bizarre, but is actually very common. The main star is a little cooler than the Sun while the smaller star is a super-cool red dwarf, the most common kind of star.
Janssen’s closeness to its star is confusing to astronomers.
As far as they know, planets form far from their stars, so what caused it to migrate? The new research measured the planet’s wobble (officially its radial velocity) as it moved across its host star, called Copernicus (or 55 Cancri), causing a slight eclipse. They did that using an instrument called the EXtreme PREcision Spectrometer (EXPRES) at the Lowell Observatory’s Lowell Discovery Telescope in Arizona.
What the researchers discovered is that Janssen orbits Copernicus along the star’s equator, unlike the other four planets known to also orbit the star. It suggests that the planet did indeed form farther out and as it moved closer the stronger gravitational pull from Copernicus altered the planet’s orbit. It has been previously thought that the nearby orbit of the red dwarf resulted in the misalignment of the planets relative to Copernicus.
The planet’s orbit broadly aligns with the star’s equator, the new research shows.
“This result really gives us one of the first constraints of this kind on how ultra-short-period planets evolve and how they end up so close to a star,” said Dr. Vedad Kunovac of Lowell Observatory and a research team member.
That’s crucial because a better understanding of how planets form and move around over time will help astronomers discover how common Earth-like environments are in the universe—and how abundant (or not) extraterrestrial life might be.
Could there be an ET on Janssen? No way! “It was likely so hot that nothing we’re aware of would be able to survive on the surface,” said study lead author Lily Zhao, a research fellow at the Flatiron Institute’s Center for Computational Astrophysics (CCA) in New York City, about where the planet originally formed away from its host star. “We’re hoping to find planetary systems similar to ours and to better understand the systems that we do know about.”
Wishing you clear skies and wide eyes.
