THE 2014 ALMA LONG BASELINE CAMPAIGN: FIRST RESULTS FROM HIGH ANGULAR RESOLUTION OBSERVATIONS TOWARD THE HL TAU REGION
THE 2014 ALMA LONG BASELINE CAMPAIGN: FIRST RESULTS FROM HIGH ANGULAR RESOLUTION OBSERVATIONS TOWARD THE HL TAU REGION
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DOI：
10.1088/2041-8205/808/1/l3
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发表时间：
2015-07-20
影响因子：
7.9
通讯作者：
Tatematsu, K.
中科院分区：
文献类型：
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作者：
Brogan, C. L.;Perez, L. M.;Tatematsu, K.
我们提出了阿塔卡马大型毫米/亚毫米阵列（阿尔马）从2014年长基线活动的尘埃连续谱和光谱线发射从HL Tau地区的观测。波长为2.9、1.3和0.87毫米的连续图像具有前所未有的0“075（10 Au）到0”025（3.5 Au）的角分辨率，揭示了围绕年轻太阳类似物HL Tau的星周盘的惊人细节水平，在所有波长下观察到明亮和黑暗的环图案。通过拟合椭圆到最明显的环，我们测量磁盘倾斜的精确值（46 °.72 +/- 0 °.05）和位置角（+138度.02 +/-0度.07）。我们获得了1.0 mm光谱指数（alpha）的高保真度图像，其范围从光学厚中心峰和两个最亮环中的alpha类似于2.0，在暗环中增加到2.3-3.0。黑暗的戒指是不是没有发射，我们估计一个晶粒的发射率指数为0.8的最里面的黑暗的戒指和较低的后续黑暗的戒指，符合一定程度的晶粒生长和演变。环是行星形成的额外线索包括它们的中心偏移随着半径的增加而增加，以及许多轨道共振的存在。在35 Au的分辨率下，我们将盘的分子组分解析为HCO+。(1-0)其在2-12 km/s（-1）的LSR速度范围内表现出与围绕类似于1.3 M圆点星星的开普勒运动一致的模式，尽管在低蓝移速度下的吸收使其复杂化。我们还偶然发现并分辨了附近的原恒星XZ Tau（A/B）和LkH alpha 358，它们的直径为2.9 mm。
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations from the 2014 Long Baseline Campaign in dust continuum and spectral line emission from the HL Tau region. The continuum images at wavelengths of 2.9, 1.3, and 0.87 mm have unprecedented angular resolutions of 0 ''.075 (10 AU) to 0 ''.025 (3.5 AU), revealing an astonishing level of detail in the circumstellar disk surrounding the young solar analog HL Tau, with a pattern of bright and dark rings observed at all wavelengths. By fitting ellipses to the most distinct rings, we measure precise values for the disk inclination (46 degrees.72 +/- 0 degrees.05) and position angle (+138 degrees.02 +/- 0 degrees.07).We obtain a high-fidelity image of the 1.0 mm spectral index (alpha), which ranges from alpha similar to 2.0 in the optically thick central peak and two brightest rings, increasing to 2.3-3.0 in the dark rings. The dark rings are not devoid of emission, and we estimate a grain emissivity index of 0.8 for the innermost dark ring and lower for subsequent dark rings, consistent with some degree of grain growth and evolution. Additional clues that the rings arise from planet formation include an increase in their central offsets with radius and the presence of numerous orbital resonances. At a resolution of 35 AU, we resolve the molecular component of the disk in HCO+. (1-0) which exhibits a pattern over LSR velocities from 2-12 km s(-1) consistent with Keplerian motion around a similar to 1.3 M-circle dot star, although complicated by absorption at low blueshifted velocities. We also serendipitously detect and resolve the nearby protostars XZ Tau (A/B) and LkH alpha 358 at 2.9 mm.