Multiple Spiral Arms in the Disk around Intermediate-mass Binary HD 34700A
Multiple Spiral Arms in the Disk around Intermediate-mass Binary HD 34700A
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DOI：
10.3847/1538-4357/aafe87
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发表时间：
2019-01
期刊：
影响因子：
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通讯作者：
J. Monnier;T. Harries;J. Bae;B. Setterholm;A. Laws;A. Aarnio;F. Adams;S. Andrews;N. Calvet
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文献类型：
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作者：
J. Monnier;T. Harries;J. Bae;B. Setterholm;A. Laws;A. Aarnio;F. Adams;S. Andrews;N. Calvet
我们提出的第一个图像的过渡盘周围的近距离双星系统HD 34700 A在偏振散射光使用双子座南双子座行星成像仪。J-和H-波段的图像揭示了一个大的（R = 0.″49 = 175 Au）腔外的多个螺旋臂结构，沿着腔内的蓝色螺旋结构。空腔壁显示出强烈的不连续性，我们清楚地看到显著的非方位角极化U_∞，这与在推断的倾角为<$42 °的圆盘内的多次散射一致。辐射传输模型沿着与新的盖亚距离表明HD 37400 A是一个年轻的（约1500万年）系统，由两颗中间质量（约200万年）恒星组成，周围有一个过渡盘，而不是像以前分类的那样是一个带有碎片盘的太阳质量双星。传统的尘埃-气体比假设会排除螺旋的重力不稳定性来源，而使用已知的外部伴星或假设的腔中的大质量原行星的流体动力学模型在没有微调气体温度的情况下都难以重现相对较大的螺旋臂俯仰角（约30°）。我们探讨的可能性，围绕着一个巨大的原行星的材料可以解释边缘的不连续性后，也考虑到阴影的影响，由一个内部磁盘。对哈勃太空望远镜存档数据的分析表明，该盘正像螺旋臂结构所预期的那样逆时针旋转，并揭示了一个新的低质量伴星，距离为6.“45。我们包括一个附录，列出了Q，U，Q，U的明确定义，纠正了文献中的一些混淆和错误。
We present the first images of the transition disk around the close binary system HD 34700A in polarized scattered light using the Gemini Planet Imager instrument on Gemini South. The J- and H-band images reveal multiple spiral-arm structures outside a large (R = 0.″49 = 175 au) cavity, along with a bluish spiral structure inside the cavity. The cavity wall shows a strong discontinuity, and we clearly see significant non-azimuthal polarization Uϕ, consistent with multiple scattering within a disk at an inferred inclination ∼42°. Radiative transfer modeling along with a new Gaia distance suggest HD 37400A is a young (∼5 Myr) system consisting of two intermediate-mass (∼2 M⊙) stars surrounded by a transitional disk and not a solar-mass binary with a debris disk, as previously classified. Conventional assumptions of the dust-to-gas ratio would rule out a gravitational instability origin to the spirals while hydrodynamical models using the known external companion or a hypothetical massive protoplanet in the cavity both have trouble reproducing the relatively large spiral-arm pitch angles (∼30°) without fine-tuning of gas temperature. We explore the possibility that material surrounding a massive protoplanet could explain the rim discontinuity after also considering effects of shadowing by an inner disk. Analysis of archival Hubble Space Telescope data suggests the disk is rotating counterclockwise as expected from the spiral-arm structure and revealed a new low-mass companion at 6.″45 separation. We include an appendix that sets out clear definitions of Q, U, Qϕ, Uϕ, correcting some confusion and errors in the literature.