We present science cases and instrument design considerations for a short-wavelength (Y/J-band), high spectral dispersion (R=25,000) instrument that could be implemented at the VLTI visitor focus. The instrument will unlock powerful venues for studying accretion and mass-loss processes at the early/late stages of stellar evolution, for detecting accreting protoplanets around young stars, and for probing the spin-orbit alignment in directly-imaged planetary systems and multiple star systems. In conjuncture with infrastructure improvements on the VLTI unit telescopes, the instrument will also enable off-axis spectroscopy of exoplanets in the 0.1-2” separation range, enabling high-SNR, high spectral resolution follow-up of exoplanets detected with ELT/JWST. We discuss technical implementations, including on fringe tracking and fast laboratory low-order adaptive optics. We outline a pathway for implementation and stress possible synergies with other instruments in the proposed ASGARD suite.
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