NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-25 T21:44:37 PDT
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For refcode 1989MNRAS.239..289S:
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NED Abstract

Copyright by Royal Astronomical Society. 1989MNRAS.239..289S Observational constraints on viscosity in AGN accretion discs A. Siemiginowska and B. Czerny N. Copernicus Astronomical Centre, Bartycka 18, 00-716 Warsaw, Poland Accepted 1989 January 23. Received 1989 January 20; in original form 1988 November 2 Summary. The optical/UV/soft X-ray big bump can be modelled as thermal emission from an accretion disc. The observed UV variability in AGN spectra may be caused by accretion-disc instabilities, and can be used to constrain the viscosity. The comparison of thermal time-scales with the observed time-scales of variability in 10 Seyfert galaxies and 16 QSO's indicates values for the parameter {alpha} of the order of 0.01 for most cases.
Retrieve 24 NED objects in this reference.
Please click here for ADS abstract

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