Planet at DW UMa?

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Planet at DW UMa?

Post by Edasich on 22nd December 2016, 4:47 am

A third body with 10 times the mass of Jupiter and nearly same orbital distance (a = 5.8 AUs) is inferred to account for period change in DW UMa

A 16-Year Photometric Campaign on the Eclipsing Novalike Variable DW Ursae Majoris

We present an analysis of photometric observations of the eclipsing novalike variable DW UMa made by the CBA consortium between 1999 and 2015. Analysis of 372 new and 260 previously published eclipse timings reveals a 13.6 year period or quasi-period in the times of minimum light. The seasonal light curves show a complex spectrum of periodic signals: both positive and negative superhumps, likely arising from a prograde apsidal precession and a retrograde nodal precession of the accretion disc. These signals appear most prominently and famously as sidebands of the orbital frequency but the precession frequencies themselves, at 0.40 and 0.22 cycles per day, are also seen directly in the power spectrum. The superhumps are sometimes seen together and sometimes separately. The depth, width and skew of eclipses are all modulated in phase with both nodal and apsidal precession of the tilted and eccentric accretion disc. The superhumps, or more correctly the precessional motions which produce them, may be essential to understanding the mysterious SW Sextantis syndrome. Disc wobble and eccentricity can both produce Doppler signatures inconsistent with the true dynamical motions in the binary, and disc wobble might boost the mass-transfer rate by enabling the hot white dwarf to directly irradiate the secondary star.

Excerpt from preprint

If we assume this third body to be the sole source of the O-C modulation, and its orbit to be coplanar with the DW UMa binary orbit, then its mass would be 10.06 MJup and its orbital radius 5.80 AU. Therefore this body, if it exists, is almost certainly planetary not stellar.
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Re: Planet at DW UMa?

Post by Lazarus on 23rd December 2016, 12:19 pm

According to section 4, the timing variations are compatible with being produced by the Applegate mechanism, so the planetary interpretation is definitely not secure here. Probably needs a few decades more observations to determine whether the variations are truly periodic.
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