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arXiv · 1305.5846

An accurate geometric distance to the compact binary SS Cygni vindicates accretion disc theory

J. C. A. Miller-Jones·G. R. Sivakoff·C. Knigge·E. G. Körding·M. Templeton·E. O. Waagen
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Abstract

Dwarf novae are white dwarfs accreting matter from a nearby red dwarf companion. Their regular outbursts are explained by a thermal-viscous instability in the accretion disc, described by the disc instability model that has since been successfully extended to other accreting systems. However, the prototypical dwarf nova, SS Cygni, presents a major challenge to our understanding of accretion disc theory. At the distance of 159 +/- 12 pc measured by the Hubble Space Telescope, it is too luminous to be undergoing the observed regular outbursts. Using very long baseline interferometric radio observations, we report an accurate, model-independent distance to SS Cygni that places the source significantly closer at 114 +/- 2 pc. This reconciles the source behavior with our understanding of accretion disc theory in accreting compact objects.

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J. C. A. Miller-Jones, G. R. Sivakoff, C. Knigge, E. G. Körding, M. Templeton, E. O. Waagen. 2013-05-24. An accurate geometric distance to the compact binary SS Cygni vindicates accretion disc theory. https://doi.org/10.1126/science.1237145

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