SPECTROSCOPIC DETECTION OF THE 3.934 MICRON LINE OF Si ix IN THE SOLAR CORONA

We report the detection of the line of Si ix using the McMath-Pierce telescope on Kitt Peak. 2 2 3 2s 2p P1 r 0 Observations were made of the solar disk and at various heights above the limb between 2002 May 13 and 17, under nonideal sky conditions, using the 13.5 m vertical spectrograph and an InSb single-diode detector. We report a new rest wavelength for the line and discuss its potential use as a diagnostic of coronal magnetic fields using ground-based telescopes. Our observations give mm, consistent with earlier less accurate l p 3.93434 0.00007 rest values, but it places the blue wing of the line under a strong telluric line. In the active regions observed, the N O 2 line’s intensity is comparable to or larger than predicted in earlier work for the quiet Sun. Subject headings: Sun: corona — Sun: infrared