The Absolute Abundance of Iron in the Solar CoronaS

We present a measurement of the abundance of Fe relative to H in the solar corona using a technique which diiers from previous spectroscopic and solar wind measurements. Our method combines EUV line data from the CDS spectrometer on SOHO with thermal bremsstrahlung radio data from the VLA. The coronal Fe abundance is derived by equating the thermal bremsstrahlung radio emission calculated from the EUV Fe line data to that observed with the VLA, treating the Fe/H abundance as the sole unknown. We apply this technique to a compact cool active region and nd Fe/H = 1.56 10 ?4 , or about 4 times its value in the solar photosphere. Uncertainties in the CDS radiometric calibration, the VLA intensity measurements, the atomic parameters, and the assumptions made in the spectral analysis yield net uncertainties 20%. This result implies that low rst ionization potential elements such as Fe are enhanced in the solar corona relative to photospheric values.