Are 'mega-Earths' real? Stellar activity may explain these oversized rocky worlds
A new study suggests that some of the heaviest rocky planets ever reported may not be as heavy as they look. These so-called 'mega-Earths,' rocky planets weighing more than about 10 Earths, could be an illusion created by activity on their host stars. The paper was posted to the arXiv preprint server on Oct. 8.
A new study suggests that some of the heaviest rocky planets, known as mega-Earths, may not be as heavy as they appear. These planets, weighing more than 10 Earth masses, could be an illusion caused by activity on their host stars. Researchers analyzed 333 planets with radial-velocity mass measurements and found eight unusually dense planets weighing more than 10 Earth masses.
Four of these were rocky, while the other four could potentially hold water or other heavy volatiles but little hydrogen-helium gas. The host stars of all eight planets were found to be active, with strong magnetic activity that could cause the planets' mass estimates to be inflated. The researchers suggest that stellar activity may be the most likely reason for the larger-than-expected masses of these mega-Earths.
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