29 frequencies for the δ Scuti variable BI CMi: the 1997-2000 multisite campaigns
29 frequencies for the δ Scuti variable BI CMi: the 1997-2000 multisite campaigns
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δ Scuti 变量 BI CMi 的 29 个频率：1997-2000 年多站点活动
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
U. Heiter
中科院分区：
文献类型：
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作者：
M. Breger;R. Garrido;G. Handler;M. Wood;R. Shobbrook;K. Bischof;F. Rodler;R. Gray;A. Stankov;P. Martínez;D. O’Donoghue;R. Szabó;W. Zima;A. B. Kaye;C. Barban;U. Heiter
从1997年到2000年，包括两个长的观测季节，BI CMi的多站点活动以优异的频率分辨率和高光度精度进行。在1024小时（177夜）的测光中，可以提取出29个脉动频率。检测到的频率包括主脉动频率范围从4.8到13.0 cycle d - 1（55到150 μHz）的20种脉动模式，这些频率的8种线性组合，以及1.66 cycle d - 1的极低频率。由于1.66周d - 1处的低频值不能用其他频率的线性组合来识别，因此怀疑是g模式脉动，但不能排除丰度点的旋转调制。BI CMi位于经典不稳定带的冷边缘附近，可能既是一颗盾牌座8星，也是一颗剑鱼座γ星星。BI CMi的另一个突出特性是功率谱中存在许多接近的频率对，其间隔小至0.01周期d - 1。由高色散谱确定了自转速度vsin i = 76 ′ 1 km s - 1。根据相位差，可以用从0到2的值来识别主导模式。研究了BI CMi的光谱类型和演化状况。
T A multisite campaign of BI CMi was carried out with excellent frequency resolution and high photometric accuracy from 1997 to 2000, including two long observing seasons. 29 pulsation frequencies could be extracted from the 1024 h (177 nights) of photometry used. The detected frequencies include 20 pulsation modes in the main pulsation frequency range from 4.8 to 13.0 cycle d - 1 (55 to 150 μHz), eight linear combinations of these frequencies, and a very low frequency at 1.66 cycle d - 1 . Since the value of the low frequency at 1.66 cycle d - 1 cannot be identified with a linear combination of other frequencies, g-mode pulsation is suspected, but rotational modulation of abundance spots cannot be ruled out. BI CMi, which is situated near the cool edge of the classical instability strip, may be both a 8 Scuti and a γ Doradus star. Another outstanding property of BI CMi is the presence of a number of close frequency pairs in the power spectrum with separations as small as 0.01 cycle d - 1 . A rotational velocity of v sin i = 76 ′ 1 km s - 1 was determined from a high-dispersion spectrum. From phase differences, the dominant modes can be identified with values from 0 to 2. The spectral type and evolutionary status of BI CMi are examined.