Small-Scale Interstellar NA I Structure toward M92

摘要: We have used integral field echelle spectroscopy with the DensePak fiber-optic array on KPNO WIYN telescope to observe central 27'' × 43'' of globular cluster M92 in Na I D wavelength region at a spatial resolution 4''. Two interstellar absorption components are evident spectra LSR velocities 0 km s-1 (cloud 1) and -19 2). Substantial strength variations both apparent down scales limited by fiber-to-fiber separations. The derived column densities differ factor 4 across cloud 1 map 7 2 map. Using distance upper limits 400 800 pc for 2, respectively, maps indicate structure medium (ISM) 1600 3200 AU. density differences toward comparable those found similar study ISM M15. Overall, structures significantly lower than interpret these low as small-scale turbulent gas compare them larger scale, higher M15, which may be hallmarks actual H structures.