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Following the enhancement in ultraviolet flux which we reported previously, we have continued monitoring the symbiotic variable SY Muscae with the International Ultraviolet Explorer (JUE). Over the course of one year, the prominent emission lines of N v, 0 v, C rv, He II appear to be gradually decreasing in absolute intensity. This appears to coincide with a steady decline in electron density in the emission line forming region, as suggested from the Sim] :\1892 and Cm] :\1909 intensity ratio. Our data is consistent with a sudden ejection event in which material expelled from the surface of a hot Teff = 65 000 K sub dwarf has exposed the underlying UV continuum of the star. A number of strong emission lines that are photoexcited by the intense radiation field of the secondary also exhibit broad pedestal emission that suggest turbulent velocities of -150-300 km s- 1 in an expanding shell or possibly in an accretion disc. The radical change of the UV emission properties observed in SY Muscae indicates that our initial observations of this object were obtained during preliminary stages of mass ejection.


This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society : 1984, published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. DOI: 10.1093/mnras/207.3.575

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Royal Astronomical Society/Oxford University Press



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