Knowledge Bank

The long awaited initial $detectionb$ of $H3+$ in the interstellar medium provides unprecedented opportunites to directly characterize the physical and chemical properties of dense molecular clouds near young stellar objects. Recent observations in the 3.7$ \mu m$ region using the CGS4 infrared spectrometer at the United Kingdom Infrared Telescope and the high-resolution Phoenix spectometer at the Kitt Peak National Observatory support the initial detection of $H3+$ and extend the use of $H3+$ as a chemical probe of the interstellar medium to other molecular clouds. The interstellar material towards many winter objects --- GL961E, MonR2 IRS 2 and IRS 3, GL490, GL989, NGC2024 IRS 2, LkH$\alpha$ 101, W3 IRS 5, and Orion BN --- have been searched in the spectral region of $H3+$, providing both positive (detection) and negative (upper limit) results. In addition, the data from the initial detection of $H3+$ in the summer objects GL2136 and W33A have been reprocessed to improve the resolution of the spectral lines.