First results from the Goodard High-Resolution Spectrograph: The chromosphere of α Tauri

The K5 III star α Tau was observed with the Goddard High Resolution Spectrograph on 1990 November 27 as part of the Science Assessment Program for the Hubble Space Telescope. The observations include spectra in both the Large and Small Science Apertures in modes G270M at 2345 Å and echelle B at 2325 Å. The spectra show intersystem and permitted chromospheric emission lines of C II], Si II], Fe II, Fe I, Ni II, and Co II. Resolved profiles of the C II] lines indicate a complex chromospheric turbulent velocity distribution with mean value of ≈24 km s^-1, while their observed wavelengths indicate a 4 km s^-1 downflow of the C II] plasma. Twenty-five new emission lines have been found in the 2320-2370 A region, 17 of which have been identified with the aid of Skylab data obtained above the solar limb, including four lines from Co II (UV 8) and an Fe I (UV 12) line. The Co II lines confirm the earlier identification of the 2330 Å line as a Co II (UV 8) fluorescent feature, and the Fe I line represents a third product of the Mg II k-Fe I pumping which produces the Fe I (UV 44) lines near 2823 and 2844 Å. The Skylab spectrum shows different line strengths due to the higher density and lower optical depths of the solar chromosphere above the visible limb.