Applegate mechanism vs planets

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Applegate mechanism vs planets

Post by Lazarus on 8th December 2015, 5:54 pm

Völschow et al. (2015) "Eclipsing time variations in close binary systems: Planetary hypothesis vs. Applegate mechanism"
http://arxiv.org/abs/1512.01960

In the cases of QS Virginis, DP Leonis, V471 Tauri and BX Draconis, the energy required to drive an Applegate mechanism is less than the available energy from the secondary star. For HU Aquarii, UZ Fornacis, HR 1099 and SZ Piscium, the ratio is approximately 1. Eight systems (HS 0705+6700, HW Virginis, NN Serpentis, NSVS 14256825, NY Virginis, RR Caeli, RU Cancri and AW Herculis) would require substantially larger amounts of available energy to drive the Applegate mechanism.
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Re: Applegate mechanism vs planets

Post by Sirius_Alpha on 2nd December 2018, 9:49 pm

High-speed photometry of the eclipsing polar UZ Fornacis
https://arxiv.org/abs/1811.12724

We present 33 new mid-eclipse times spanning approximately eight years of the eclipsing polar UZ Fornacis. We have used our new observations to test the two-planet model previously proposed to explain the variations in its eclipse times measured over the past ∼35 years. We find that the proposed model does indeed follow the general trend of the new eclipse times, however, there are significant departures. In order to accommodate the new eclipse times, the two-planet model requires that one or both of the planets require highly eccentric orbits, that is, e≥ 0.4. Such multiple planet orbits are considered to be unstable. Whilst our new observations are consistent with two cyclic variations as previously predicted, significant residuals remain. We conclude that either additional cyclic terms, possibly associated with more planets, or other mechanisms, such as the Applegate mechanism are contributing to the eclipse time variations. Further long-term monitoring is required.

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