A strange exoplanet has been found just 31 light-years away.
It's one of the smallest exoplanets ever discovered, just slightly larger than Mars, and it's also one of the most compact, with a density almost the same as that of pure iron. It's close to its host star and can complete one full orbit once every eight hours.
The discovery of this planet is an important one, but it's not known how it formed.
The Institute of Planetary Research at the German Aerospace Center has determined that GJ is a rocky planet.
It seems like it has similarities to Mercury. This places it among the sub- Earth sized planets and brings research one step forward in the search for a second Earth.
The way we hunt for exoplanets results in certain biases that we end up finding. The transit method relies on looking for small dips in starlight as an exoplanet moves between us and its host star.
Since a larger exoplanet will result in a bigger dip in starlight, and pass in front of the star more frequently, this will favor large exoplanets on close-hood.
The wobble method relies on the wavelength of a star's light changing as an exoplanet's pull causes it to move. The stronger the signal, the bigger the exoplanet. Smaller exoplanets are harder to detect.
GJ 362b was something of a lucky discovery. It was detected by NASA's exoplanet-hunting space telescope TESS because it is so close. TESS looks at the sky for dips in starlight.
The research team figured out how big the transiting exoplanet is by looking at the dips.
The radial velocity method was used to see how much the exoplanet's pull affects the star. They were able to calculate the mass of GJ 362b and its density of 8.106 grams per square meter. At room temperature, iron's density is 7.874 grams per cubic centimeter, while Earth's is 5.51 grams.
This could tell us something about the composition of the exoplanet, since we have something similar here in the Solar System.
The astronomer Szilrd Csizmadia of the German Aerospace Center said that the planet is dominated by an iron core. The iron and nickel core of Mercury differentiates it from other bodies in the Solar System.
It's not possible that GJ is a second Earth. The exoplanet is tidally locked, with one side facing the star, and subject to absolutely scorching radiation, because of its close proximity.
That climate is not suitable for humans.
The discovery of GJ 362b could lead to other worlds that are more hospitable.
George Ricker of MIT's Kavli Institute for Astrophysics and Space Research said that the star's habitable zone would be between two and three weeks.
We have a good chance of seeing other planets in this system since this star is so close by. It's like there's a sign saying, "Look here for extra planets!"
The team's research has been published.
