RS CVn双星zeta And的椭球主天体：用高分辨光谱学和光学干涉测量学研究
Ellipsoidal primary of the RS CVn binary zeta And: Investigation using high-resolution spectroscopy and optical interferometry
摘要：
我们获得了RS CVn型双星系统zeta And的椭球主星的高分辨光谱、光干涉和长时宽谱测光。基于光学干涉测量法，使用均匀圆盘拟合，zeta Δ的表观边缘变暗直径为2.55 +/-0.09质量。依巴谷距离和边缘变暗的直径由均匀的圆盘拟合得到，恒星半径为15.9 +/- 0.8 Rsolar，结合热光度，它意味着有效温度为4665 +/- 140 K。使用多普勒成像从高分辨率光谱获得的温度图显示了赤道斑点的强烈带和冷极冠的暗示。赤道点显示在相位0.75附近的浓度。这个点的配置让人想起了在早期发表的zeta And温度图中看到的。对H α线的研究揭示了色球层中的双折射和冷云。跨越12年的长期测光显示了一个斑点活动周期的迹象，这也是多普勒图像所暗示的，但周期长度不能从目前的数据中可靠地确定。
英文摘要：
We have obtained high-resolution spectroscopy, optical interferometry, and long-term broad band photometry of the ellipsoidal primary of the RS CVn-type binary system zeta And. Based on the optical interferometry the apparent limb darkened diameter of zeta And is 2.55 +/- 0.09 mas using a uniform disk fit. The Hipparcos distance and the limb-darkened diameter obtained with a uniform disk fit give stellar radius of 15.9 +/- 0.8 Rsolar, and combined with bolometric luminosity, it implies an effective temperature of 4665 +/- 140 K. The temperature maps obtained from high resolution spectra using Doppler imaging show a strong belt of equatorial spots and hints of a cool polar cap. The equatorial spots show a concentration around the phase 0.75. This spot configuration is reminiscent of the one seen in the earlier published temperature maps of zeta And. Investigation of the Halpha line reveals both prominences and cool clouds in the chromosphere. Long-term photometry spanning 12 years shows hints of a spot activity cycle, which is also implied by the Doppler images, but the cycle length cannot be reliably determined from the current data.
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