Inner cavities and annular gaps in circumstellar disks are possible signposts of giant planet formation. The young star HD 142527 hosts a massive protoplanetary disk with a large cavity that extends up to 140 AU from the central star, as seen in continuum images at infrared and millimeter wavelengths. Estimates of the survival of gas inside disk cavities are needed to discriminate between clearing scenarios. We present a spatially and spectrally resolved carbon monoxide isotopologue observations of the gas-rich disk HD 142527, in the J = 2-1 line of 12CO, 13CO, and C18O obtained with the Atacama Large Millimeter/submillimeter Array (ALMA). We detect emission coming from inside the dust-depleted cavity in all three isotopologues. Based on our analysis of the gas in the dust cavity, the 12CO emission is optically thick, while 13CO and C18O emissions are both optically thin. The total mass of residual gas inside the cavity is ~1.5-2 M Jup. We model the gas with an axisymmetric disk model. Our best-fit model shows that the cavity radius is much smaller in CO than it is in millimeter continuum and scattered light observations, with a gas cavity that does not extend beyond 105 AU (at 3σ). The gap wall at its outer edge is diffuse and smooth in the gas distribution, while in dust continuum it is manifestly sharper. The inclination angle, as estimated from the high velocity channel maps, is 28 ± 0.5?deg, higher than in previous estimates, assuming a fix central star mass of 2.2 M ☉.
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机译：星际盘中的内腔和环形间隙可能是巨型行星形成的路标。年轻的恒星HD 142527拥有一个巨大的原行星盘，该行星盘上有一个大空腔，从中央恒星一直延伸到140 AU，如在红外和毫米波波长的连续图像中所见。需要估算磁盘腔内气体的存活率，以区分清理方案。我们在Atacama大毫米/亚毫米阵列（ALMA）获得的富含CO的磁盘HD 142527的J = 2-1线的12CO，13CO和C18O上进行空间和光谱解析的一氧化碳同位素同位素观测。我们在所有三个同位素分子中都检测到来自粉尘耗尽腔内部的发射。根据我们对粉尘腔中气体的分析，12CO的排放在光学上较厚，而13CO和C18O的排放在光学上均较薄。腔内残留气体的总质量约为1.5-2 M Jup。我们使用轴对称盘模型对气体进行建模。我们的最佳拟合模型显示，在CO中，腔半径比在连续毫米波和散射光观测中要小得多，并且气腔的延伸范围不会超过105 AU（在3σ）。间隙壁在其外边缘在气体分布中是扩散且平滑的，而在粉尘连续体中则明显更尖锐。根据高速通道图估算的倾角为28±0.5°，比以前的估算值高，假定中心恒星质量为2.2 M fix。
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