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Paper: FUSE Observations of the Post-AGB Star ZNG 1 in the Globular Cluster M5 (NGC 5904)
Volume: 296, New Horizons in Globular Cluster Astronomy
Page: 236
Authors: van Dyke Dixon, W.; Brown, T. M.; Landsman, W. B.
Abstract: We report observations of the hot post-asymptotic giant branch (PAGB) star ZNG 1 in the globular cluster M5 (NGC 5904) with the Far Ultraviolet Spectroscopic Explorer (FUSE). From the resulting spectrum, we derive an effective temperature Teff = 45 +/- 1 kK, a surface gravity log g = 4.3 +/- 0.1, and a rotational velocity v sin i = 170 +/- 20 km/s. The star's luminosity, log (L/Lsun) = 3.54 +/- 0.06, is consistent with its PAGB classification. The atmosphere is helium-rich (Y = 0.92), with enhanced carbon (2.9% by mass), nitrogen (0.43%), and oxygen (0.37%) abundances. The spectrum shows evidence for a stellar wind with terminal velocity near 1000 km/s and an expanding shell of carbon- and nitrogen-rich material. This work is supported by NASA grant NAG 5-10405.
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