質量-光度比のダイナミックな校正が,非常に低い恒星質量と若い年齢において行われました
Laird M Close1, Rainer Lenzen, Jose C Guirado
1Steward Observatory, University of Arizona, Tucson, Arizona 85721, USA. lclose@as.arizona.edu
Nature
|January 22, 2005
まとめ
天文学者は,若い低質量恒星の同伴星の質量を正確に測定しました. この発見は,標準的な質量-明るさ関係が,そのような物体の近赤外線の明るさを過大評価し,茶色矮星の周波数推定に影響することを明らかにしています.
科学分野:
- 天文学と天体物理学について
- 恒星の進化について
- エクソプラネット研究
背景:
- 恒星の質量は基本的ですが,直接測定することは困難です.
- 現在の質量推定は,質量-明るさ関係に依存しており,これは若い低質量恒星や茶色矮星では十分に調整されていません.
- 理論的なモデルは,これらのオブジェクトの質量を制限するためにしばしば使用されます.
研究 の 目的:
- 若い低質量恒星伴星 (AB Dor C) の質量を動的に測定する.
- 若い低質量物体の標準質量-明るさ関係の精度を再評価する.
- これらの発見が,茶色矮星と惑星質量物体の周波数の推定に与える影響を評価する.
主な方法:
- 新しい高コントラスト適応光学カメラを使用して,同伴星を発見し,解像しました.
- 伴星の質量を正確に決定するために,動的方法を使用した.
- 伴侶の近赤外線 (1〜2ミクロメートル) の明るさを測定しました.
主要な成果:
- 低質量同伴星ABドールCの質量は,0.090 +/- 0.005太陽質量であると動的に決定しました.
- 標準的な質量-明るさ関係が,若い低質量物体の近赤外線の明るさを約2.5.の因数で過大評価することを発見しました.
- 若くて冷たい物体の以前に推定された質量は,2の因数で過小評価されている可能性があることが示されています.
結論:
- 質量-光度関係には,若い低質量恒星や茶色矮星については,大幅な修正が必要である.
- 若い恒星群における茶色矮星や惑星質量の天体の頻度は,おそらく過大評価されている.
- ダイナミックな直接的な質量測定は,恒星および亜恒星質量-明るさ関係を正確に校正するために不可欠です.
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