  As part of Villanova's Living with a Red Dwarf program, we have obtained UV,
X-ray and optical data of the Population II red dwarf -- Kapteyn's Star.
Kapteyn's Star is noteworthy for its large proper motions and high RV of ~+245
km s^-1. As the nearest Pop II red dwarf, it serves as an old age anchor for
calibrating Activity/Irradiance-Rotation-Age relations, and an important test
bed for stellar dynamos and the resulting X-ray -- UV emissions of slowly
rotating, near-fully convective red dwarf stars. Adding to the notoriety,
Kapteyn's Star has recently been reported to host two super-Earth candidates,
one of which (Kapteyn b) is orbiting within the habitable zone (Anglada-Escude
et al. 2014a, 2015). However, Robertson et al. (2015) questioned the planet's
existence since its orbital period may be an artifact of activity, related to
the star's rotation period. Because of its large Doppler-shift, measures of the
important, chromospheric H I Lyman-alpha 1215.67A emission line can be reliably
made, because it is mostly displaced from ISM and geo-coronal sources.
Lyman-alpha emission dominates the FUV region of cool stars. Our measures can
help determine the X-ray--UV effects on planets hosted by Kapteyn's Star, and
planets hosted by other old red dwarfs. Stellar X-ray and Lyman-alpha emissions
have strong influences on the heating and ionization of upper planetary
atmospheres and can (with stellar winds and flares) erode or even eliminate
planetary atmospheres. Using our program stars, we have reconstructed the past
exposures of Kapteyn's Star's planets to coronal -- chromospheric XUV emissions
over time.
