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تسجيل مستخدم جديدA Circular Planetary Nebula around the OH/IR Star OH 354.88-0.54 (V1018 Sco)
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Martin Cohen
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New deep, high-resolution H-alpha imagery from the UK Schmidt Telescope (UKST) Units H-alpha survey of the Southern Galactic Plane reveals the presence of a faint, highly circular, planetary nebula surrounding a very long period variable star (now known as V1018 Sco), first discovered as a 1612-MHz OH maser, OH 354.88-0.54. The nebular phase-lag distance, diameter, and radial velocity are 3.2kpc, 0.3pc, and 13km/s, respectively. Combining the maser attributes with near-, mid-, and far-infrared data and with our optical spectrum of the ring we conclude that the object was an intermediate mass AGB star (initial stellar mass >4Msun in which the fast wind has recently turned on, ionizing previously shed circumstellar material. Hence, we speculate that we may be witnessing a hitherto unobserved phase of PN evolution, in which a PN has only recently started to form around a star that is unequivocally still in its AGB
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