Detecting a rotation in the epsilon Eridani debris disc

Abstract

The evidence for a rotation of the epsilon Eridani debris disc is examined. Data at 850 micron wavelength were previously obtained using the Submillimetre Common User Bolometer Array (SCUBA) over periods in 1997-1998 and 2000-2002. By chi-square fitting after shift and rotation operations, images from these two epochs were compared to recover proper motion and orbital motion of the disc. The same procedures were then performed on simulated images to estimate the accuracy of the results. Minima in the chi-square plots indicate a motion of the disc of approximately 0.6'' per year in the direction of the star's proper motion. This underestimates the true value of 1'' per year, implying that some of the structure in the disc region is not associated with epsilon Eridani, originating instead from background galaxies. From the chi-square fitting for orbital motion, a counterclockwise rotation rate of ~2.75 degrees per year is deduced. Comparisons with simulated data in which the disc is not rotating show that noise and background galaxies result in approximately Gaussian fluctuations with a standard deviation +/-1.5 degrees per year. Thus counterclockwise rotation of disc features is supported at approximately a 2-sigma level, after a 4-year time difference. This rate is faster than the Keplerian rate of 0.65 degrees per year for features at ~65 AU from the star, suggesting their motion is tracking a planet inside the dust ring. Future observations with SCUBA-2 can rule out no rotation of the epsilon Eridani dust clumps with ~4-sigma confidence. Assuming a rate of about 2.75 degrees per year, the rotation of the features after a 10-year period could be shown to be >1 degree per year at the 3-sigma level.

8 pages, 6 figures

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• Low Resolution Spectral Templates For Galaxies From 0.2 -- 10 microns
• The Northern Arc of $\epsilon$ Eridani's Debris Ring as Seen by ALMA
• Deep LMT/AzTEC millimeter observations of Epsilon Eridani and its surroundings
• Extragalactic gamma-ray signal from Dark Matter annihilation: a power spectrum based computation
• The clumpy structure of $\epsilon$ Eridani's debris disc revisited by ALMA
• Confirming the Primarily Smooth Structure of the Vega Debris Disk at Millimeter Wavelengths
• An Improved Semi-Analytical Spherical Collapse Model for Non-linear Density Evolution
• MAMBO image of the debris disk around epsilon Eridani : robustness of the azimuthal structure
• Impact of planetesimal eccentricities and material strength on the appearance of eccentric debris disks
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