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An accurate geometric distance to the compact binary SS Cygni vindicates accretion disc theory
J C A Miller-Jones1, G R Sivakoff, C Knigge
1International Centre for Radio Astronomy Research, Curtin University, Perth, WA 6845, Australia. james.miller-jones@curtin.edu.au
Science (New York, N.Y.)
|May 25, 2013
Summary
Accurate distance measurements reveal SS Cygni is closer than previously thought. This finding resolves a major challenge to accretion disc theory for dwarf novae.
Area of Science:
- * Astrophysics
- * Stellar evolution
- * Accretion physics
Background:
- * Dwarf novae are binary systems with white dwarfs accreting matter from red dwarfs.
- * Their outbursts are explained by the disc instability model.
- * The dwarf nova SS Cygni challenges this model due to its previously estimated luminosity.
Purpose of the Study:
- * To accurately determine the distance to SS Cygni.
- * To reconcile SS Cygni's observed behavior with accretion disc theory.
- * To resolve discrepancies in understanding accretion in compact objects.
Main Methods:
- * Employed very long baseline interferometric (VLBI) radio observations.
- * Utilized a model-independent approach for distance determination.
- * Incorporated precise parallax measurements.
Main Results:
- * Determined a new, accurate distance to SS Cygni of 114 ± 2 parsecs.
- * This revised distance is substantially closer than the previous Hubble Space Telescope estimate of 159 ± 12 parsecs.
- * The new distance resolves the luminosity paradox for SS Cygni's outbursts.
Conclusions:
- * The revised distance to SS Cygni aligns its behavior with the disc instability model.
- * This study reinforces the validity of accretion disc theory for compact objects.
- * Accurate distance measurements are crucial for understanding astrophysical phenomena.
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