ウェッブ宇宙望遠鏡、岩石質太陽系外惑星を取り巻く大気の可能性を示唆(NASA’s Webb Hints at Possible Atmosphere Surrounding Rocky Exoplanet)

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2024-05-08 NASA

ウェッブ宇宙望遠鏡、岩石質太陽系外惑星を取り巻く大気の可能性を示唆(NASA’s Webb Hints at Possible Atmosphere Surrounding Rocky Exoplanet)
This artist’s concept shows what the exoplanet 55 Cancri e could look like based on observations from NASA’s James Webb Space Telescope and other observatories. Observations from Webb’s NIRCam and MIRI suggest that the planet may be surrounded by an atmosphere rich in carbon dioxide (CO2) or carbon monoxide (CO). Researchers think the gases that make up the atmosphere could have bubbled out of an ocean of magma that is thought to cover the planet’s surface. NASA, ESA, CSA, Ralf Crawford (STScI)

NASAのジェームズ・ウェッブ宇宙望遠鏡を使った研究者たちは、地球から41光年離れた高温の岩石型系外惑星「55 Cancri e」の周囲に大気が存在する可能性を確認しました。これは太陽系外で岩石惑星の大気が発見された最も有力な証拠です。研究チームは、赤外線観測データからこの惑星が炭素を含む大気に包まれた溶岩の海に覆われていることを示唆し、その大気が内部から放出されていると考えられています。この発見は、岩石型惑星の大気の形成や進化を理解する上で重要であり、地球や金星、火星の初期の状態に関する洞察をもたらす可能性があります。

<関連情報>

岩石で覆われた太陽系外惑星55カンクリの二次大気 A secondary atmosphere on the rocky Exoplanet 55 Cancri e

Renyu Hu,Aaron Bello-Arufe,Michael Zhang,Kimberly Paragas,Mantas Zilinskas,Christiaan van Buchem,Michael Bess,Jayshil Patel,Yuichi Ito,Mario Damiano,Markus Scheucher,Apurva V. Oza,Heather A. Knutson,Yamila Miguel,Diana Dragomir,Alexis Brandeker & Brice-Olivier Demory
Nature  Published:08 May 2024
DOI:https://doi.org/10.1038/s41586-024-07432-x

We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply.

Abstract

Characterizing rocky exoplanets is a central endeavor of astronomy, and yet the search for atmospheres on rocky exoplanets has hitherto resulted in either tight upper limits on the atmospheric mass1–3 or inconclusive results4–6. The 1.95-REarth and 8.8-MEarth planet 55 Cnc e, with a predominantly rocky composition and an equilibrium temperature of ~2000 K, may have a volatile envelope (containing molecules made from a combination of C, H, O, N, S, and P elements) that accounts for up to a few percent of its radius7–13. The planet has been observed extensively with transmission spectroscopy14–22, and its thermal emission has been measured in broad photometric bands23–26. These observations disfavor a primordial H2/He-dominated atmosphere but cannot conclusively determine whether the planet has a secondary atmosphere27,28. Here we report a thermal emission spectrum of the planet obtained by JWST’s NIRCam and MIRI instruments from 4 to 12 μm. The measurements rule out the scenario where the planet is a lava world shrouded by a tenuous atmosphere made of vaporized rock29–32, and indicate a bona fide volatile atmosphere likely rich in CO2 or CO. This atmosphere can be outgassed from and sustained by a magma ocean.

1701物理及び化学
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