太陽系外惑星の双子星の軌道に珍しいねじれを発見(Astronomers find rare twist in exoplanet’s twin star orbit)

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2025-04-17 バーミンガム大学

バーミンガム大学を中心とする国際研究チームは、太陽系外惑星「2M1510 (AB) b」が、2つの若い褐色矮星の連星を直角(90度)の軌道で公転する「ポーラープラネット(極軌道惑星)」であることを発見した。これは観測史上初の明確な証拠であり、連星系における惑星形成の常識を覆すもの。この珍しい軌道は、ESOのVLT望遠鏡での高精度観測と、軌道パラメータを30倍精度で解析する独自手法により明らかとなった。本研究は、惑星と恒星の相互作用や連星系における動的進化の理解を深める成果とされる。

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食褐色矮星のペアを周回する極周連星系外惑星の証拠 Evidence for a polar circumbinary exoplanet orbiting a pair of eclipsing brown dwarfs

Thomas A. Baycroft, Lalitha Sairam, Amaury H. M. J. Triaud, and Alexandre C. M. Correia
Science Advances  Published:16 Apr 2025
DOI:https://doi.org/10.1126/sciadv.adu0627

太陽系外惑星の双子星の軌道に珍しいねじれを発見(Astronomers find rare twist in exoplanet’s twin star orbit)

Abstract

One notable example of exoplanet diversity is the population of circumbinary planets, which orbit around both stars of a binary star system. There are, so far, only 16 known circumbinary exoplanets, all of which lie in the same orbital plane as the host binary. Suggestions indicate that circumbinary planets could also exist on orbits highly inclined to the binary, close to 90°, polar orbits. No such planets have been found yet, but polar circumbinary gas and debris discs have been observed, and if these were to form planets, then those would be left on a polar orbit. We report strong evidence for a polar circumbinary exoplanet, which orbits a close pair of brown dwarfs that are on an eccentric orbit. We use radial velocities to measure a retrograde apsidal precession for the binary and show that this can only be attributed to the presence of a polar planet.

1700応用理学一般
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