FR Cnc再访：光度、旋光和光谱
FR Cnc Revisited: Photometry, Polarimetry and Spectroscopy
摘要：
在这里，我们提出的研究FR Cnc，一个年轻的，活跃的和斑点的明星。对2002-2008年ASAS-3（The All Sky Automated Survey）卫星资料进行了分析，并将自转周期修正为0.826518 d。在2005年，光度变化的幅度突然下降，而平均亮度保持不变，这被解释为快速重新分布的斑点。对FR Cnc附近的166颗恒星进行了BVRc和Ic宽波段光度定标。Terskol天文台的测光显示了两个增亮事件，其中一个与2006年11月23日的耀斑发生在同一阶段。偏振BVR观测表明可能存在一个补充源的偏振。我们在2004-2008年期间用光谱法监测FR Cnc。我们得出结论，RV的变化不能用FR Cnc的二进制性质来解释。我们确定FR Cnc的光谱类型为K7 V。计算的银河系空间速度分量（U，V，W）表明，FR Cnc属于年轻的盘人口，也可能属于IC 2391移动群。根据LiI 6707.8测量，我们估计FR Cnc的年龄在10-120百万年之间。多普勒断层扫描应用于创建FR Cnc的星点图像。我们优化了轴倾角、等效宽度和v sin i的反卷积剖面的拟合优度，发现v sin i=46.2 km s^-1，i=55 °。FR Cnc的星点分布也令人感兴趣，因为它是最新成像的光谱类型之一。在FR Cnc上未检测到极点。
英文摘要：
Here we present the study of FR Cnc, a young, active and spotted star. We performed analysis of ASAS-3 (The All Sky Automated Survey) data for the years 2002-2008 and amended the value of the rotational period to be 0.826518 d. The amplitude of photometric variations decreased abruptly in the year 2005, while the mean brightness remained the same, which was interpreted as a quick redistribution of spots. BVRc and Ic broad band photometric calibration was performed for 166 stars in FR Cnc vicinity. The photometry at Terskol Observatory shows two brightening episodes, one of which occurred at the same phase as the flare of 2006 November 23. Polarimetric BVR observations indicate the probable presence of a supplementary source of polarization. We monitored FR Cnc spectroscopically during the years 2004-2008. We concluded that the RV changes cannot be explained by the binary nature of FR Cnc. We determined the spectral type of FR Cnc as K7V. Calculated galactic space-velocity components (U, V, W) indicate that FR Cnc belongs to the young disc population and might also belong to the IC 2391 moving group. Based on LiI 6707.8 measurement, we estimated the age of FR Cnc to be between 10-120 Myr. Doppler Tomography was applied to create a starspot image of FR Cnc. We optimized the goodness of fit to the deconvolved profiles for axial inclination, equivalent width and v sin i, finding v sin i=46.2 km s^-1 and i=55 degrees. The starspot distribution of FR Cnc is also of interest since it is one of the latest spectral types to have been imaged. No polar spot was detected on FR Cnc.
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