CCD Photometry of 2060 Chiron in 1985 and 1991
CCD Photometry of 2060 Chiron in 1985 and 1991
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1985 年和 1991 年 2060 Chiron 的 CCD 光度测量
DOI：
10.1006/icar.1993.1098
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发表时间：
1993
期刊：
影响因子：
3.2
通讯作者：
B. Buratti
中科院分区：
文献类型：
--
作者：
R. Marcialis;B. Buratti
本文报道了2060凯龙星的两次CCD测光。1985年1月获得了部分光变曲线，当时该天体的本质比之前或之后看到的都要暗（Hv = 6.84）。尽管如此，即使在那时也有一些彗星活动的证据;裸露的核可能更暗。在1991年1月8日获得了10小时的完整光变曲线。与1990年J. X. Luu和D.C. Jewitt（1990，Astron. J. 100，913-932），它在三个重要方面有所不同。振幅较低（0.04 MAG），平均亮度水平高于最近的趋势将预测（平均HR = 5.65），和平均保持恒定超过1 - 1 - 2旋转内优于0.005 MAG。光变曲线显示可重复的结构相对较高的频率（15分钟的时间尺度），以前归因于噪声。这些特征在夜间重复出现，也可以在1986年的光变曲线中看到。J. Bus，E. Bowell，A. W. Harris，和A.休伊特，1989，伊卡洛斯77，223-238）。我们相信这个结构是凯龙星更像非球面的证据（刻面？）比小振幅光变曲线所暗示的要多。旋转光变曲线现在已经有了足够好的特征，不再需要在一个完整的旋转过程中获得数据来监测物体的所谓“爆发”行为。我们希望这将鼓励观察者在几天到几周的时间尺度上研究凯龙星的彗星行为。更新的平均会合周期为5.917813 ± 0.000007小时，并利用新的数据建立了一个修正的核+彗差光度模型。这个模型的结果，沿着观察到的快速“辍学”的旋转光变曲线，一起作为一个相对较低的折射率在过去的十年中观看几何的证据。
Abstract We report CCD photometry of 2060 Chiron from two apparitions. A partial light curve was obtained in 1985 January, when the object was intrinsically fainter (Hv = 6.84) than it has ever been seen before or since. Nonetheless, there was some evidence for cometary activity even then; the bare nucleus may be fainter still. A complete light curve was obtained over 10 hr on 1991 January 08. Similar in character to the 1990 lightcurve of J. X. Luu and D.C. Jewitt (1990, Astron. J. 100, 913-932), it differed in three important respects. The amplitude was lower (0.04 mag), the mean brightness level was higher than recent trends would predict (mean HR = 5.65), and the mean remained constant over 1 1 2 rotations to within better than 0.005 mag. The light curve shows reproducible structure of relatively high-frequency (∼15-min time scale), formerly attributed to noise. These features repeat within the night and also may be discerned in light curves dating back to 1986 (S. J. Bus, E. Bowell, A. W. Harris, and A. V. Hewitt, 1989, Icarus 77, 223-238). We believe this structure to be evidence that Chiron is more aspherical (faceted?) than the small-amplitude lightcurve otherwise implies. The rotational lightcurve now is sufficiently well-characterized that it is no longer necessary to obtain data over a complete rotation to monitor the so-called "outburst" behavior of the object. We hope that this will encourage observers to study the cometary behavior of Chiron on time scales of days to weeks. An updated mean synodic period of 5.917813 ± 0.000007 hr has been derived, and a revised nucleus + coma photometric model is constructed using the new data. The results of this model, along with the observed rapid "dropouts" in the rotational lightcurve, are together taken as evidence for a relatively low-obliquity viewing geometry over the past decade.