Babcock星的竞争者：Ap星HD 75049的极端30- kG可变磁场

A Solar Dynamo Model Driven by Mean-Field Alpha and Babcock-Leighton Sources: Fluctuations, Grand-Minima-Maxima and Hemispheric Asymmetry in Sunspot Cycles

Extreme solar activity fluctuations and the occurrence of solar grand minima and maxima episodes, are well established, observed features of the solar cycle. Nevertheless, such extreme activity fluctuations and the dynamics of the solar cycle during Maunder minima-like episodes remain ill-understood. We explore the origin of such extreme solar activity fluctuations and the role of dual poloidal field sources, namely the Babcock-Leighton mechanism and the mean-field alpha effect in the dynamics of the solar cycle. We mainly concentrate on entry and recovery from grand minima episodes such as th…

The star-forming complex LMC-N79 as a future rival to 30 Doradus

Within the early Universe, `extreme' star formation may have been the norm rather than the exception. Super Star Clusters (SSCs; $M_\star$ $\gtrsim$ 10$^5$ M$_\odot$) are thought to be the modern-day analogs of globular clusters, relics of a cosmic time ($z$ $\gtrsim$ 2) when the Universe was filled with vigorously star-forming systems. The giant HII region 30 Doradus in the Large Magellanic Cloud (LMC) is often regarded as a benchmark for studies of extreme star formation. Here, we report the discovery of a massive embedded star forming complex spanning $\sim$ 500 pc in the unexplored southwe…

Discovery of an extremely weak magnetic field in the white dwarf LTT 16093 = WD2047+372

Magnetic fields have been detected in several hundred white dwarfs, with strengths ranging from a few kG to several hundred MG. Only a few of the known fields have a mean magnetic field modulus below about 1 MG. We are searching for new examples of magnetic white dwarfs with very weak fields, and trying to model the few known examples. Our search is intended to be sensitive enough to detect fields at the few kG level. We have been surveying bright white dwarfs for very weak fields using spectropolarimeters at the Canada-France-Hawaii telescope, the William Herschel telescope, the European Sout…

随机强迫时滞太阳发电机模型：从Maunder-like巨极小值的自洽恢复需要平均场α效应

A Stochastically Forced Time Delay Solar Dynamo Model: Self-Consistent Recovery from a Maunder-like Grand Minimum Necessitates a Mean-Field Alpha Effect

太阳磁场活动的波动，包括像蒙德极小期这样的大极小期，对空间和行星环境有着重要的影响。然而，这种极端波动的基本动力仍然不清楚。在这里，我们使用一种新的数学模型的基础上随机强迫，非线性延迟微分方程研究太阳周期波动，其中，时间延迟捕获物理之间的空间隔离发电机源区域在太阳内部的磁通量运输。使用这个模型，我们明确地表明，Babcock-Leighton极向场源的基础上分散的倾斜双极太阳黑子通量，单独，不能恢复太阳黑子周期从一个盛大的最小值。我们发现，一个额外的极向场源有效的弱场-螺旋湍流驱动的平均场α效应-是必要的太阳黑子周期的自洽恢复从盛大极小事件。

Performance and Early Science with the Subaru Coronagraphic Extreme Adaptive Optics Project

We describe the current performance of the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument on the Subaru telescope on Maunakea, Hawaii and present early science results for SCExAO coupled with the CHARIS integral field spectrograph. SCExAO now delivers H band Strehl ratios up to $\sim$ 0.9 or better, extreme AO corrections for optically faint stars, and planet-to-star contrasts rivaling that of GPI and SPHERE. CHARIS yield high signal-to-noise detections and 1.1--2.4 $μm$ spectra of benchmark directly-imaged companions like HR 8799 cde and kappa And b that clarify their atmosp…

测量太阳磁性的隐藏方面

Measuring the Hidden Aspects of Solar Magnetism

2008年是天体物理学磁场发现100周年，当时乔治·埃勒里·黑尔记录了太阳黑子中谱线的塞曼分裂。随着巴布科克的光电磁力仪的引入，人们很快就清楚地看到，太阳黑子外的太阳磁场是极其结构化的。当空间分辨率提高时，所测量的场强被发现变得更大。因此，有必要提出超越空间分辨率极限的方法，并在不依赖所用望远镜质量的情况下诊断固有磁场特性。线比技术是在20世纪70年代初发展起来的，它揭示了这样一幅图景：我们在磁图中看到的大部分磁通量都起源于高度成束的、具有微小体积填充因子的千克场。这导致了对嵌入在相当无场介质中的离散强场磁通量管的解释，以及整个行业的磁通量管模型越来越复杂。随着高精度成像偏振仪的出现，这种磁场模式现在已经被打破，这种偏振仪使我们能够应用所谓的“第二太阳光谱”来诊断塞曼诊断法所隐藏的太阳磁场方面。据发现，光球体积的大部分是沸腾与中等强度，纠缠领域。在新的范例中，该领域表现得像一个具有高度自相似性的分形，跨越约8个数量级的规模大小，下至10米的规模。