活动冷星与He I 10830 π：日冕联系
Active cool stars and He I 10830 Å: the coronal connection
摘要：
He I 10830 A三重态在冷恒星中的形成机制在过去的30年里一直是争论的主题。在冷恒星中发现了X射线光度和He I 10830 A通量之间的关系，但这些恒星的主要形成机制（日冕辐射光电离，然后是复合和级联，或色球层中的碰撞激发）尚未建立。我们使用现代仪器（NOT/SOFIN）和直接测量的EUV通量，光电离他我，调查的最活跃的恒星，经常被排除在分析线的形成机制。我们以前所未有的分辨率（R~ 170，000）在一组15颗恒星中观测到He I 10830 A三重态，这些恒星也被极紫外探测器（EUVE）观测到，以便将谱线强度与它们的EUV和X射线通量进行比较。活动矮星和次巨星的EUV通量与He I 10830 A线的等效宽度之间没有关系。然而，巨星的He I 10830 A吸收强度与EUV和X射线通量之间存在正相关。C IV 1550 A发射的强度与这15颗恒星样本中的日冕通量无关。活跃的矮星可能有高的色球密度，从而使碰撞激发占主导地位的光电离/复合过程中形成的He I 10830 A线。活动巨星拥有较低的重力，色球密度比矮星低，允许光激发过程变得重要。此外，它们的扩展色球层允许红外连续辐射的散射，在He I中产生强吸收并跟踪风动力学。
英文摘要：
The mechanism of formation of the He I 10830 A triplet in cool stars has been subject of debate for the last 30 years. A relation between the X-ray luminosity and the He I 10830 A flux was found in cool stars, but the dominant mechanism of formation in these stars (photoionization by coronal radiation followed by recombination and cascade, or collisional excitation in the chromosphere), has not yet been established. We use modern instrumentation (NOT/SOFIN) and a direct measurement of the EUV flux, which photoionizes He I, to investigate the formation mechanism of the line for the most active stars which are frequently excluded from analysis. We have observed with an unprecedented resolution (R~170,000) the He I 10830 A triplet in a set of 15 stars that were also observed with the Extreme Ultraviolet Explorer (EUVE) in order to compare the line strengths with their EUV and X-ray fluxes. Active dwarf and subgiant stars do not exhibit a relation between the EUV flux and the equivalent width of the He I 10830 A line. Giant stars however, show a positive correlation between the strength of the He I 10830 A absorption and the EUV and X-ray fluxes. The strength of the C IV 1550 A emission does not correlate with coronal fluxes in this sample of 15 stars. Active dwarf stars may have high chromospheric densities thus allowing collisional excitation to dominate photoionization/recombination processes in forming the He I 10830 A line. Active giant stars possess lower gravities, and lower chromospheric densities than dwarfs, allowing for photoexcitation processes to become important. Moreover, their extended chromospheres allowfor scattering of infrared continuum radiation, producing strong absorption in He I and tracing wind dynamics.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
