A Spectroscopic Study of the Three Symbiotic Stars He 2-171, AP 1-9, and AP 1-11

Line intensities of the symbiotic stars He 2-171, Ap 1-9, and Ap 1-11 between 3700 A and 6900 A have been measured; He 2-171 has a particularly rich spectrum filled with the usual forbidden iron lines. Densities estimated from auroral-to-nebular line ratios are high, 2 x 10 to the 6th and 4 x 10 to the 7th/cu cm from forbidden O III for He 2-171 and Ap 1-9, respectively, and 300,000 from forbidden N II for He 2-171, while the nebular forbidden S II ratio gives a much lower density for He 2-171 of 10,000, typical of symbiotic behavior. Comparison with other observations of He 2-171 strongly indicates physical changes in the system over a four-year period. The spectrum of Ap 1-9 has a strong underlying continuum with TiO bands, indicating the presence of an M star.