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Session 64 - Globular Clusters.
Oral session, Tuesday, January 14
Jacoby amp; Fullton (1994, BAAS, 26, 1384) searched 133 of the \sim150 Galactic globular clusters for Planetary Nebulae (PNe) using the on-band/off-band imaging technique at [O III] \lambda5007ÅWe present preliminary abundances and central star properties for the 2 new PN identified in that survey (labeled JaFu 1 and JaFu 2 by Acker, Marcout, amp; Ochsenbein 1996).
JaFu 1 (diameter of 8" = 0.22 pc) in Pal 6 has low excitation and is located 230" from the cluster center. This separation suggests that JaFu 1 may instead be a bulge planetary, yet its velocity (176 km/s) and extinction (E_B-V=1.9) are more-or-less consistent with membership. Preliminary model results derived from limited spectral coverage ground-based data suggest the following central star properties: 0.55 M_ødot, T_eff=90,000K, L=800L_ødot. Nebular abundances are [He/H]=-0.04, [O/H]=-0.4, [N/H]=0.0, [S/H]=-0.7. Pal 6 is metal-rich ([Fe/H]\approx +0.2 dex; Minniti 1995), so if JaFu 1 is a member, the nebula is oxygen-poor relative to iron.
(2) JaFu 2 (diameter of 5" = 0.22 pc) in NGC 6441 is very likely a cluster member, having similar velocity (37 km/s), and extinction (E_B-V=0.4), in addition to being close to the cluster center (37"). It has extremely high excitation levels, and so very few optical lines are seen. We will present a revised analysis that includes imminently arriving UV spectra from HST; for now, models reproducing all spectral contraints define the following parameters for the central star: 0.56 M_ødot, T_eff=100,000K, L=2000L_ødot. The nebula abundances are: [He/H]=+0.16, [O/H]=-0.8, [Ne/H]=-0.6. The stars in NGC 6441 have [Fe/H]=-0.5 (Armandroff 1989); thus, this nebula also is oxygen-poor relative to iron.
Also, we serendipitously found an OH/IR star at 68" west of Ter 2, by virtue of its very red color (V-I > 8), which allowed a detection through a tiny red leak in the [OIII] filter. The star may be coincident with IRAS 17242-3045, having OH/IR-like colors.
Program listing for Tuesday