銀河系外起源の金属が少ない恒星の周りを回る巨大な惑星
Johny Setiawan1, Rainer J Klement, Thomas Henning
1Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany. setiawan@mpia.de
まとめ
天文学者は,進化の遅い段階にある恒星HIP 13044を周回する木星のような惑星を発見した. この系外惑星は,天の川銀河系外から誕生した可能性が高い.
科学分野:
- 天文学と天体物理学について
- エクソプラネット科学 エクソプラネット科学
- 恒星の進化について
背景:
- 水平分岐星のように,後期期の恒星の周りの惑星の仲間は,ほとんど未探査のままです.
- HIP 13044は,赤色の水平分岐に位置する金属が少ない恒星で,系外惑星検出のユニークなターゲットとなっています.
研究 の 目的:
- 水平分岐星の周りの惑星の存在を調査するために.
- 検出された惑星の仲間を特徴づけ,その性質を決定する.
主な方法:
- 放射速度観測を高解像度スペクトログラフで利用し,マックス・プランク・Gesellschaft-European Southern Observatoryの2.2メートルの望遠鏡で観測した.
- 周期的な放射速度変動を分析して,惑星のサインを特定し,恒星の活動と区別しました.
主要な成果:
- HIP13044の周りに惑星の伴星が検出され,最小質量は木星の質量1.25である.
- この惑星は,0.116天文学単位の半大軸で,周期が16.2日とする軌道に回っています.
結論:
- この系外惑星が金属が少ない水平分岐星の周りを回っていることが発見されたことで,惑星形成の既知のパラメータ空間が拡大した.
- HIP13044の起源が衛星銀河から発生したことから,惑星は銀河系外起源であると仮定され,多様な銀河環境における惑星形成の洞察を提供している.
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