F. L. Crawford[1], F. P. Keenan[1], B. R. Espey[2], M. Mathioudakis[1],
K. M. Aggarwal[1], W. A. Feibelman[3] and F. C. McKenna[1]
[1] The Queen's University of Belfast, UK
[2] Space Telescope Science Institute, USA
[3] Goddard Space Flight Center, USA
An inspection of a GHRS/HST spectrum of the symbiotic star RR Telescopii reveals the presence of the [Al II] 3s^2 ^1S - 3s3p ^3P_2 line at a vacuum wavelength of 2661.06± 0.08Å, 8.89± 0.08Å away from the [Al II] 3s^2 ^1S - 3s3p ^3P_1 intercombination transition at 2669.95Å, in good agreement with the theoretical prediction of Delta_lambda=8.80Å. We also find that the [Al II] line profile is asymmetric, showing a strong low density component with a weak high density wing, redshifted by 30 km/s, in agreement with the findings of Schild & Schmid which were based on optical observations. Our measurement of the emission line ratio R=I(2661.06Å)/I(2669.95Å)=0.027± 0.003 implies log N_e=5.8± 0.2, in good agreement with the densities found from other ions, such as Si III. These results provide strong evidence that we have detected the [Al II] line, the first time (to our knowledge) that this feature has been reliably identified in an astrophysical or laboratory spectrum.