We present Doppler images of RS CVn-type binary II Peg based on two data sets obtained in 2004 February and November. In order to improve signal-to-noise ratio and reliability, we apply least-squares deconvolution technique to calculate average profiles from 2032 photospheric absorption lines. Both of the resulting surface images show a wide latitude distribution of starspots. Most spots are concentrated at a high-latitude belt above 60 degrees and a low-latitude belt near equator. The starspots evolved dramatically between two observing runs, which may indicate shorter time-scale evolution in this epoch, especially for low-latitude belt. There is no stable preferred active longitude that can be found in our images. We also find out a possible phenomenon that the intermediate-latitude spot migrated poleward and merged with the high-latitude spot to make it stronger, which may reveal a more complex behaviour of starspots on II Peg. A potential change of orbital ephemeris zero-point was detected. This may imply an orbital period change of II Peg like other active close binaries.

中文翻译：

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2004年RS CVn双星II Pegasi星斑分布与演化

我们展示了基于 2004 年 2 月和 11 月获得的两个数据集的 RS CVn 型二进制 II Peg 的多普勒图像。为了提高信噪比和可靠性，我们应用最小二乘解卷积技术来计算 2032 条光球吸收线的平均分布。由此产生的两个表面图像都显示了星点的广泛纬度分布。大多数点集中在60度以上的高纬带和赤道附近的低纬带。两次观测之间的星斑演化显着，这可能表明这一时期的时间尺度演化较短，尤其是低纬度带。在我们的图像中找不到稳定的首选活动经度。我们还发现了一个可能的现象，即中纬度点向两极迁移并与高纬度点合并使其更强，这可能揭示了 II Peg 上星点的更复杂行为。检测到轨道星历零点的潜在变化。这可能意味着 II Peg 的轨道周期变化，就像其他活跃的近双星一样。