DETECTION AND TRACKING OF SUBTLE CLOUD FEATURES ON URANUS
DETECTION AND TRACKING OF SUBTLE CLOUD FEATURES ON URANUS
复制标题
天王星上微妙的云特征的检测和跟踪
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
K. Rages
中科院分区：
文献类型：
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作者：
P. Fry;L. Sromovsky;I. de Pater;H. Hammel;K. Rages
最近更新的天王星纬向风廓线（Sromovsky等人）样本纬度范围为71° S至73° N。但由于缺乏可跟踪的云特征，许多纬度仍然严重采样不足（20°-45° S和20°-50° N以外）。我们最近发现的低对比度云提供了一些填补这些空白的希望，它可以通过比以前获得的高得多的信噪比（S/Ns）成像来揭示。这是使用2007年凯克II NIRC 2近红外观测的平均值来证明的。11个一分钟的H波段曝光，在1.6小时的时间跨度内获得，直线重新映射和纬向转移，以考虑行星旋转。这使S/N增加了约3.3倍。纬度带出现了新的精细结构，以前无法观测到的小云迹变得清晰可见，一些微弱的云特征变得突出。虽然我们可以产生这样一个高质量的平均值，但我们无法产生足够的数据来实际跟踪新发现的特征。这需要一个专门设计的观测努力。我们已经设计了最近的哈勃空间望远镜WFC 3 F845 M观测，以允许应用该技术。我们通过跟踪这些图像中的特征测量了八个纬向风，发现有几个从Sromovsky等人的当前纬向风廓线上脱落，并且与它们的半球不对称轮廓的部分逆转相一致。
The recently updated Uranus zonal wind profile (Sromovsky et al.) samples latitudes from 71° S to 73° N. But many latitudes remain grossly undersampled (outside 20°–45° S and 20°–50° N) due to a lack of trackable cloud features. Offering some hope of filling these gaps is our recent discovery of low-contrast cloud that can be revealed by imaging at much higher signal-to-noise ratios (S/Ns) than previously obtained. This is demonstrated using an average of 2007 Keck II NIRC2 near-IR observations. Eleven one-minute H-band exposures, acquired over a 1.6 hr time span, were rectilinearly remapped and zonally shifted to account for planetary rotation. This increased the S/N by about a factor of 3.3. A new fine structure in latitude bands appeared, small previously unobservable cloud tracers became discernible, and some faint cloud features became prominent. While we could produce one such high-quality average, we could not produce enough to actually track the newly revealed features. This requires a specially designed observational effort. We have designed recent Hubble Space Telescope WFC3 F845M observations to allow application of the technique. We measured eight zonal winds by tracking features in these images and found that several fall off of the current zonal wind profile of Sromovsky et al., and are consistent with a partial reversal of their hemispherically asymmetric profile.