Evidence for Mass-dependent Circumstellar Disk Evolution in the 5 Myr Old Upper Scorpius OB Association
Evidence for Mass-dependent Circumstellar Disk Evolution in the 5 Myr Old Upper Scorpius OB Association
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DOI：
10.1086/509121
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发表时间：
2006-09
期刊：
影响因子：
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通讯作者：
J. Carpenter;E. Mamajek;L. Hillenbrand;M. Meyer
中科院分区：
文献类型：
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作者：
J. Carpenter;E. Mamajek;L. Hillenbrand;M. Meyer
我们用斯皮策太空望远镜对上天蝎座OB星群的204颗恒星进行了4.5、8和16 μm的光度测定。这些数据被用来研究质量在~0.1和20 M☉之间、年龄在~5 Myr的恒星周围的星周盘的频率和性质。我们发现有35颗恒星的辐射比恒星光球高出8或16 μm。较低质量的恒星（~0.1-1.2 M☉）似乎被原始光学厚度的圆盘所包围，这是基于过量发射的特征。质量大于~1.8 M☉的恒星有较低的分数过剩光度，这表明盘的内部~10 AU已经大量耗尽了原始物质。在我们的样品中没有G和F星（~1.2-1.8 M☉）在波长≤16 μm处有红外过量。这些结果表明，对于低质量恒星，分散原始光学厚盘的机制平均效率较低，并且对于质量小于1 M☉的恒星，在陆地带中可以获得较长的时间尺度来建立行星系统。
We present 4.5, 8, and 16 μm photometry from the Spitzer Space Telescope for 204 stars in the Upper Scorpius OB association. The data are used to investigate the frequency and properties of circumstellar disks around stars with masses between ~0.1 and 20 M☉ at an age of ~5 Myr. We identify 35 stars that have emission at 8 or 16 μm in excess of the stellar photosphere. The lower mass stars (~0.1-1.2 M☉) appear surrounded by primordial optically thick disks based on the excess emission characteristics. Stars more massive than ~1.8 M☉ have lower fractional excess luminosities suggesting that the inner ~10 AU of the disk has been largely depleted of primordial material. None of the G and F stars (~1.2-1.8 M☉) in our sample have an infrared excess at wavelengths ≤16 μm. These results indicate that the mechanisms for dispersing primordial optically thick disks operate less efficiently, on average, for low-mass stars, and that longer timescales are available for the buildup of planetary systems in the terrestrial zone for stars with masses ≲1 M☉.