Characterizing the morphology of the debris disk around the low-mass star GSC 07396-00759
Characterizing the morphology of the debris disk around the low-mass star GSC 07396-00759
复制标题
表征低质量恒星 GSC 07396-00759 周围碎片盘的形态
DOI：
10.1051/0004-6361/202140740
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发表时间：
2021
影响因子：
6.5
通讯作者：
Adam C
中科院分区：
文献类型：
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作者：
Adam C
碎片盘通常被研究在中等质量恒星周围。它们强烈的辐射场被认为可以有效地清除不断通过碰撞补充的小尘埃颗粒。利用VLT/SPHERE IRDIS双光束偏振成像模式对前主序星M型星星GSC 07396-00759周围的近边缘盘进行了新的观测，并对M型恒星的尘埃清除机制进行了研究。的目的，以更好地了解磁盘的形态，其灰尘的属性，和通过恒星质量损失率的星盘相互作用。MethodsWe模型的极化观测，以表征的位置和属性的尘埃颗粒使用的Henyey-Greenstein近似的极化相位函数。结果我们发现偏振光观测最好用一个扩展的、高度倾斜的圆盘（i = 84.3 ° ± 0.3）来描述，其尘埃分布的中心半径为0 Au.我们的建模表明，各向异性散射因子g = 0.6，以最好地再现偏振相位函数S12。我们还发现，尺寸> 0.3μm的小微米尺寸尘埃颗粒可以相当好地再现相函数。我们讨论的方法的一些警告，主要是我们的模型可能不会完全恢复磁盘的半长轴，我们不能很容易地确定所有的灰尘属性由于晶粒大小和孔隙度之间的简并性。我们的最佳拟合模型不仅很好地再现了观测结果，而且与以前公布的总强度数据一致。类似于以前的研究碎片盘，我们建议，使用一个给定的散射理论可能不足以充分解释的关键方面，如形状的相函数或尘埃颗粒大小。考虑到上述警告，我们发现GSC 07396-00759的平均质量损失率可能比太阳高出500倍，这支持了来自低质量恒星的恒星风可以有效地疏散小尘埃颗粒的观点。
ContextDebris disks have commonly been studied around intermediate-mass stars. Their intense radiation fields are believed to efficiently remove the small dust grains that are constantly replenished by collisions. For lower-mass central objects, in particular M stars, the dust removal mechanism needs to be further investigated given the much weaker radiation field produced by these objects.AimsWe present new observations of the nearly edge-on disk around the pre-main-sequence M-type star GSC 07396-00759, taken with VLT/SPHERE IRDIS in dual-beam polarimetric imaging mode, with the aim to better understand the morphology of the disk, its dust properties, and the star-disk interaction via the stellar mass-loss rate.MethodsWe model the polarimetric observations to characterize the location and properties of the dust grains using the Henyey–Greenstein approximation of the polarized phase function. We use the estimated phase function to evaluate the strength of the stellar winds.ResultsWe find that the polarized light observations are best described by an extended and highly inclined disk (i≈ 84.3 ° ± 0.3) with a dust distribution centered at a radiusr0≈ 107 ± 2 au. Our modeling suggests an anisotropic scattering factorg≈ 0.6 to best reproduce the polarized phase functionS12. We also find that the phase function is reasonably well reproduced by small micron-sized dust grains with sizess> 0.3μm. We discuss some of the caveats of the approach, mainly that our model probably does not fully recover the semimajor axis of the disk and that we cannot readily determine all dust properties due to a degeneracy between the grain size and the porosity.ConclusionsEven though the radius of the disk may be overestimated, our best-fit model not only reproduces the observations well but is also consistent with previous published data obtained in total intensity. Similarly to previous studies of debris disks, we suggest that using a given scattering theory might not be sufficient to fully explain key aspects, such as the shape of the phase function or the dust grain size. Taking into consideration the aforementioned caveats, we find that the average mass-loss rate of GSC 07396-00759 can be up to 500 times stronger than that of the Sun, supporting the idea that stellar winds from low-mass stars can evacuate small dust grains in an efficient way.