NEAR-INFRARED CONSTRAINTS ON THE PRESENCE OF WARM DUST AT METAL-RICH, HELIUM ATMOSPHERE WHITE DWARFS
NEAR-INFRARED CONSTRAINTS ON THE PRESENCE OF WARM DUST AT METAL-RICH, HELIUM ATMOSPHERE WHITE DWARFS
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近红外对富含金属的氦大气白矮星中存在的暖尘埃的限制
DOI：
10.1088/0004-6256/136/1/111
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Sandy Leggett
中科院分区：
文献类型：
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作者：
M. Kilic;M. Kilic;J. Farihi;A. Nitta;Sandy Leggett
我们介绍了在NASA红外望远镜设备上获得的15颗氦大气中富金属白矮星的近红外光谱观测。虽然已经证明了污染最严重的氢气大气中的白矮星与温暖的星际尘埃和气体之间的联系，但它们在氦大气中的频率变化很少受到限制。我们的目标都没有显示出与热轨道物质一致的过量近红外辐射。将这些近红外约束添加到之前的近红外和中红外观测中，对于以氢为主的光球来说，金属白矮星上温暖的星际物质的频率至少是20%，但对于那些有效地由氦组成的光球来说，可能不到5%。氦大气白矮星周围尘埃盘的低出现率与质量对流区光球金属的MYR时间尺度是一致的。通过对10颗具有较热星周物质的白矮星质量分布的分析，我们寻找到了围绕中等质量恒星的大质量行星的盘状分布频率与预测的大质量行星的分布趋势之间的相似趋势，但发现具有盘状分布的白矮星质量大于平均值的概率并不显著。
We present near-infrared spectroscopic observations of 15 helium atmosphere, metal-rich white dwarfs obtained at the NASA Infrared Telescope Facility. While a connection has been demonstrated between the most highly polluted, hydrogen atmosphere white dwarfs and the presence of warm circumstellar dust and gas, their frequency at the helium atmosphere variety is poorly constrained. None of our targets shows excess near-infrared radiation consistent with warm orbiting material. Adding these near-infrared constraints to previous near- and mid-infrared observations, the frequency of warm circumstellar material at metal-bearing white dwarfs is at least 20% for hydrogen-dominated photospheres, but could be less than 5% for those effectively composed of helium alone. The lower occurrence of dust disks around helium atmosphere white dwarfs is consistent with Myr timescales for photospheric metals in massive convection zones. Analyzing the mass distribution of ten white dwarfs with warm circumstellar material, we search for similar trends between the frequency of disks and the predicted frequency of massive planets around intermediate-mass stars, but find the probability that disk-bearing white dwarfs are more massive than average is not significant.