SIMBAD references

Medium-resolution (R∼460) spectra in the K window have been obtained for the compact H II regions W51 IRS 2 East and IRS 2 West. Brγ, He I, three lines of [Fe III], and seven lines of molecular hydrogen (H₂) have been detected. The unidentified line at 2.288 µm was also detected with ∼2% of the intensity of Brγ. We derive an electron density of ∼10⁵-10⁶ cm^–3 in both IRS 2 East and IRS 2 West from [Fe III] line ratios. In both regions, observed H₂ line ratios indicate that the excitation of H₂ is dominated by fluorescence rather than by shocks.