Stellar and Solar Magnetic Activity Cycles

拟议的计划是洛厄尔天文台太阳-恒星光谱仪(SSS)项目的继续。它的目的是在三个基本的时间尺度上更好地理解冷恒星中的活动：活动周期(以年为数量级)、自转(月)和短期(天)。SSS光谱仪覆盖了几个重要的色球诊断线，包括Ca II H和H；K和Ha，以及5000-9000 A的大部分光谱。它是一台专用仪器，与洛厄尔天文台的1.1米望远镜相关联。它通过光纤馈送接收星光，但也配备了单独的光纤馈送，将太阳视为一个未分解的圆盘。因此，太阳光和星光的记录是相同的。PI建议通过以下方式研究SSS光谱：[1]对响应太阳和恒星活动的谱线中的涌现通量的时间序列观测揭示了存在的活动周期的相位、幅度和形态。SSS目标清单包括位于主序列太阳位置附近的恒星(大致的光谱类型F5-K7)，重点是与太阳非常相似的最小演化恒星，以及太阳本身。[2]对太阳和恒星的季节变化的研究揭示了旋转调制的程度--辐射水平的变化不是由活动周期引起的，而是由于活动区域穿过可见半球而引起的。[3]光谱到光谱的变化，检查了广泛的相关谱线集合，揭示了太阳和恒星活动在短时间和长时间尺度上的变化。提出者目前正在观测太阳和大约100颗特别有趣的恒星(从最初调查的大约300颗恒星中挑选出来)。他们的数据库包括自1994年以来在大约1000天内记录的大约3000次太阳观测，以及1.6万个恒星光谱。建议者的太阳时间序列是从第22周的衰退期到第23周的衰退期。周期和长期活动在他们的许多恒星目标中都很明显，包括现在不活跃的威尔逊山天文台香港项目中的大量目标。需要进一步的观测来研究周期过程中不同时间尺度上的恒星活动--特别是那些现在从希巴谷天体测量学(以及从地面光谱学和光度学)被确定为低活动、未演化的“太阳孪生”候选恒星。

The proposed program is a continuation of the Solar-Stellar Spectrograph (SSS) project at Lowell Observatory. Its purpose is to provide a better understanding of activity in cool stars on three essential timescales: activity-cyclic (on the order of years), rotational (months), and short-term (days). The SSS spectrograph covers several important chromospheric diagnostic lines, including Ca II H&K and Ha, as well as most of the optical spectrum from 5000-9000 A. It is a dedicated instrument, associated with Lowell Observatory's 1.1-m telescope. It receives starlight via a fiber optic feed, but is also equipped with a separate fiber feed that sees the Sun as an unresolved disk. Sunlight and starlight are therefore recorded identically. The PI proposes to study SSS spectra in the following ways:[1] Time series observations of the emergent flux in spectral lines responsive to solar and stellar activity reveals the phase, amplitude, and morphology of activity cycles present. The SSS target list includes stars lying near the Sun's location on the main sequence (roughly spectral types F5 - K7), with emphasis on minimally evolved stars very similar to the Sun, as well as the Sun itself.[2] Examination of seasonal variability for the Sun and stars reveals the degree of rotational modulation - the change in emission level arising not from the activity cycle, but from the passage of active regions across the visible hemispheres.[3] The spectrum-to-spectrum variability, examined across a broad ensemble of related spectral lines, reveals changes in solar and stellar activity on both short and long timescales.The proposers are currently observing the Sun and approximately 100 particularly interesting stars (selected from about 300 stars initially surveyed). Their database comprises approximately 3000 observations of the Sun recorded over roughly 1000 days since 1994, as well as 16,000 stellar spectra. The proposers' solar time series runs from the declining phase of Cycle 22 to the declining phase of Cycle 23. Cyclic and long-term activity is apparent in many of their stellar targets, including a large number included in the now inactive Mount Wilson Observatory HK project. Further observations are required to study stellar activity on various timescales over the course of the cycles -- in particular, those stars now identified from Hipparcos astrometry (and from ground-based spectroscopy and photometry) as low-activity, unevolved, "solar twin" candidates.