Stellar and Solar Magnetic Activity Cycles

恒星和太阳磁活动周期

• 批准号: 0447159
• 负责人: Jeffrey Hall
• 金额: $ 43.53万
• 依托单位: Lowell Observatory
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-12-01 至 2007-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0447159&HistoricalAwards=false
• 关键词: Stellar; Solar; Magnetic; Activity; Cycles

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.

拟议的计划是洛厄尔天文台太阳-恒星光谱仪（SSS）项目的延续。它的目的是提供一个更好的了解在三个基本的时间尺度上的冷星活动：活动周期（年的顺序），旋转（月），和短期（天）。SSS摄谱仪覆盖了几条重要的色球诊断线，包括Ca II H K和Ha，以及5000-9000 A的大部分光谱。它是一个专用仪器，与洛厄尔天文台的1.1米望远镜有关。它通过光纤接收星光，但也配备了一个单独的光纤馈源，将太阳视为一个未解决的圆盘。因此，太阳光和星光的记录是相同的。PI建议以下列方式研究SSS光谱：[1]对响应太阳和恒星活动的光谱线中的出射通量进行时间序列观测，揭示了活动周期的相位，幅度和形态。SSS的目标列表包括位于主序星上靠近太阳位置的恒星（光谱类型大致为F5 - K7），重点是与太阳非常相似的最低演化恒星，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--发射水平的变化不是由活动周期引起的，而是由活动区穿过可见半球引起的。[3]在广泛的相关谱线系综上检查光谱间的变化，揭示了太阳和恒星活动在短期和长期尺度上的变化，提议者目前正在观测太阳和大约100颗特别令人感兴趣的恒星（从最初调查的大约300颗恒星中选出）。他们的数据库包括自1994年以来大约1000天内记录的大约3000次太阳观测，以及16，000个恒星光谱。建议者的太阳时间序列从第22周的下降阶段到第23周的下降阶段。周期性和长期的活动在他们的许多恒星目标中是明显的，包括现在不活跃的威尔逊山天文台香港项目中的大量恒星。需要进一步观测，以研究周期过程中不同时间尺度上的恒星活动，特别是现在根据依巴谷天体测量学（以及地面光谱学和光度学）确定为低活动、未演化的“太阳孪生”候选者的那些恒星。