First results from the UHRF: ultra-high-resolution observations of interstellar CH, Formula and CN towards Formula Ophiuchi

We present ultra-high-resolution observations |$(R > 700 \ 000)$| of interstellar CH, |CH⁺| and CN towards |ζ| Oph obtained with the newly commissioned Ultra-High-Resolution Facility (UHRF) at the AAT. The molecular lines have all been fully resolved, and we discuss their implications for this well-studied molecular sightline. The CH and CN lines each consist of two narrow |(b ≈ 0.5\,\ km\,\ s⁻¹)| components separated by |1.13 ± 0.10\,\ km\,\ s⁻¹|⁠; an additional broad |(b=1.8\,\ km\,\ s⁻¹)| component is present in CH. We show that the very broad |(b=2.1\,\ km\,\ s⁻¹)\,\ CH⁺| line profile is consistent with the formation of this molecule in warm haloes surrounding the cold cores responsible for the narrow CH and CN components.