We report the detection of CH₃OH emission in comet 46P/Wirtanen on UT 2018 December 8 and 9 using the Atacama Compact Array (ACA), part of the Atacama Large Millimeter/Submillimeter Array (ALMA). These interferometric measurements of CH₃OH along with continuum emission from dust probed the inner coma (<2000 km from the nucleus) of 46P/Wirtanen approximately one week before its closest approach to Earth (Δ = 0.089–0.092 au), revealing rapidly varying and anisotropic CH₃OH outgassing during five separate ACA executions between UT 23:57 December 7 and UT 04:55 December 9, with a clear progression in the spectral line profiles over a timescale of minutes. We present spectrally integrated flux maps, production rates, rotational temperatures, and spectral line profiles of CH₃OH during each ACA execution. The variations in CH₃OH outgassing are consistent with Wirtanen’s 9 hr nucleus rotational period derived from optical and millimeter wavelength measurements and thus are likely coupled to the changing illumination of active sites on the nucleus. The consistent blue offset of the line center indicates enhanced CH₃OH sublimation from the sunward hemisphere of the comet, perhaps from icy grains. These results demonstrate the exceptional capabilities of the ACA for time-resolved measurements of comets such as 46P/Wirtanen.

我们报告CH的检测₃ OH发射在彗星46P / Wirtanen使用阿塔卡马紧凑阵列（ACA），阿塔卡马大型毫米/亚毫米波阵列（ALMA）的一部分上UT 2018年12月8和9。CH的这些干涉测量₃ OH与来自灰尘连续辐射沿着探测的内昏迷46P / Wirtanen的（<2000从细胞核公里）其最接近地球之前大约一周（Δ= 0.089-0.092 AU），揭示快速变化和各向异性CH ₃OH期间UT 23时57分12月7日和UT 4点55年12月9之间五个单独的ACA处决脱气，并在谱线轮廓在几分钟的时间尺度的明确进展。我们提出光谱集成磁通图，生产速率，旋转的温度，和CH的谱线轮廓₃各ACA执行期间OH。在CH变化₃ OH除气与从光学和毫米波长测量中导出Wirtanen的9小时核旋转周期一致，从而有可能连接到在核上的活性位点的变化的发光的。一致蓝线中心的偏移指示增强CH ₃从彗星的向阳半球，也许是从冰粒OH升华。这些结果表明ACA的彗星，如46P / Wirtanen的时间分辨测量的特殊能力。