Gregor@night: The future high-resolution stellar spectrograph for the GREGOR solar telescope

摘要

We describe the future night-time spectrograph for the GREGOR solar telescope and present its science core projects. The spectrograph provides a 3-pixel resolution of up to R = 87 000 in 45 échelle orders covering the wavelength range 390-900 nm with three grating settings. An iodine cell can be used for high-precision radial velocity work in the 500-630 nm range. The operation of the spectrograph and the telescope will be fully automated without the presence of humans during night-time and will be based on the successful STELLA control system. Future upgrades include a second optical camera for even higher spectral resolution, a Stokes-V polarimeter and a link to the laser-frequency comb at the Vacuum Tower Telescope. The night-time core projects are a study of the angular-momentum evolution of "The Sun in Time" and a continuation of our long-term Doppler imaging of active stars.