Constraints on the structure of hot exozodiacal dust belts
Constraints on the structure of hot exozodiacal dust belts
复制标题
热外生尘带结构的制约
DOI：
10.1093/mnras/stx202
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发表时间：
2017
影响因子：
4.8
通讯作者：
R. Brunngräber
中科院分区：
文献类型：
--
作者：
F. Kirchschlager;S. Wolf;A.V. Krivov;H. Mutschke;R. Brunngräber
最近对附近主序星的干涉测量显示，大约有20多个系统，即大约10%至30%的被测恒星存在微弱但显著的近红外线过剩。这种过剩是由于位于星星附近的尘埃，其起源是高度争议的。我们使用以前发表的干涉观测来约束这种热尘埃的性质和分布。考虑到散射辐射和热再发射，我们模拟了9个系统中观察到的过剩。我们发现，晶粒必须有足够的吸收，以符合所观察到的过量，而纯硅酸盐组合物的介电晶粒未能再现的意见。尘埃应该位于距离星星0.01-1 Au的范围内，这取决于它的光度。此外，我们发现一个显着的趋势，光盘半径增加恒星光度。尘埃颗粒被确定在半径之下，但在半径之上。尘埃质量为（0.2-3.5）× 10− 9 M。近红外过量可能主要是由热再发射，虽然散射光的贡献高达35%不能完全排除。我们的模型预测的极化度总是低于5%，对于小于1%的颗粒甚至低于1%。我们还对另外10个在中红外数据较差的系统的近红外过量进行了建模。这些系统的基本结果似乎定性相似，但对尘埃的位置和粒度的约束较弱。
Recent interferometric surveys of nearby main-sequence stars show a faint but significant near-infrared excess in roughly two dozen systems, i.e. around 10–30 per cent of stars surveyed. This excess is attributed to dust located in the immediate vicinity of the star, the origin of which is highly debated. We used previously published interferometric observations to constrain the properties and distribution of this hot dust. Considering both scattered radiation and thermal re-emission, we modelled the observed excess in nine of these systems. We find that grains have to be sufficiently absorbing to be consistent with the observed excess, while dielectric grains with pure silicate compositions fail to reproduce the observations. The dust should be located within ∼0.01–1 au from the star depending on its luminosity. Furthermore, we find a significant trend for the disc radius to increase with the stellar luminosity. The dust grains are determined to be below, but abovein radius. The dust masses amount to (0.2–3.5) × 10− 9M⊕. The near-infrared excess is probably dominated by thermal re-emission, though a contribution of scattered light up to 35 per cent cannot be completely excluded. The polarization degree predicted by our models is always below 5 per cent, and for grains smaller thaneven below 1 per cent. We also modelled the observed near-infrared excess of another 10 systems with poorer data in the mid-infrared. The basic results for these systems appear qualitatively similar, yet the constraints on the dust location and the grain sizes are weaker.
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DOI：
--
发表时间：
2011
期刊：
影响因子：
--
作者：
L. Churcher;M. Wyatt;G. Duchêne;B. Sibthorpe;G. Kennedy;B. Matthews;P. Kalas;J. Greaves;K. Su;G. Rieke
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DOI：
10.1088/0004-637x/798/2/125
发表时间：
2015-01
期刊：
The Astrophysical Journal
影响因子：
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作者：
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DOI：
--
发表时间：
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期刊：
影响因子：
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作者：
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DOI：
--
发表时间：
2008
期刊：
影响因子：
--
作者：
R. Akeson;D. Ciardi;R. Millan;A. Mérand;E. D. Folco;J. D. Monnier;C. Beichman;O. Absil;J. Aufdenberg;H. Mcalister;T. Brummelaar;J. Sturmann;L. Sturmann;N. Turner
通讯作者：
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