Monday

Since the 1930's it has been known that sunspots are cool enough to allow for the formation of diatomic molecules. Early work by Richardson and Babcock inspired Wöhl to investigate the existence of diatomic molecules in the umbrae of sunspots, investigating the existence of 41 molecules and using a method based on wavelength coincidence on experimental rotational line intensity.

We have been generating computational linelists for SrH and BaH molecules calculated using the ExoMol methodology of refining high ab-initio quantum chemistry calculations (MRCI level, V5Z basis sets) with experimental spectroscopic data. SrH is expected to be present in sunspot umbrae (Ramachandran et al. 2006, Gaur et al. 1973). Numerous attempts to identify BaH have been made, with recent work by Karthikeyan et al. 2020 predicting a potential presence using computed rotational temperature values.

At present linelists for the X²Σ⁺ states for SrH and BaH have been completed to an accuracy on the order of 0.1 cm⁻¹ (1 part in 10⁴) or better. Currently work is progressing to include 3 low-lying electronic states for SrH and 4 low-lying states for BaH. The vibrational and rotational coverage varies by state, but are within the region of V=25 and J=65.5, far exceeding existing experimentally measured transitions. Emissions for low-lying states of SrH and BaH are in the Near-IR and Visible part of the spectrum. These should be visible to the Cryo-NIRSP, and VISP instruments on the DKIST telescope. The final linelists will be computed for all major isotopoglogues of the SrH and BaH molecules including the deuterium counterparts, and are predicted to be complete and applicable for temperatures upto 5000K.