By Leah Crane.
The star of the exoplanet GJ
SPP 1992 was written byPatricia Klein.
A group of planets that are so close to their stars that their years are less than one Earth day are made mostly of iron.
The weird world, called GJ , was found by the Technical University of Berlin and their colleagues using the Transiting Exoplanet Survey Satellite. The follow-up observations were done using the High Accuracy Radial velocity Planet Searcher.
They found that the exoplanet has a mass just over half of our planet's. It probably has an iron core that takes up about 86 per cent of its radius, similar to Mercury, and they were able to predict its interior structure with those measurements.
Some hot exoplanets may have strange sets of storms.
The densest and smallest of the ultra-short-period planets is found on this planet. The side of the planet that faces the star has a temperature of 1400C.
This is close to the melting point of iron and hotter than the dayside of Mercury. It could help explain why so much of the planet is taken up by its core, when most other relatively small planets have thick, rocky mantles and crusts.
The heat from the star could have boiled off the rest of the planet over time. This could be the remains of a planet smaller than Neptune.
It will take more observations to be sure, but the star's relative brightness will make ongoing study easy. There are hints of a second planet in the system, which will need follow-up observations to confirm.
The journal has a reference in it.
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