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High-speed photometry of the eclipsing polar UZ Fornacis
摘要： 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 yr. 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.
关键词： planets and satellites: detection,planets and satellites: formation,stars: individual: UZ Fornacis,novae, cataclysmic variables,binaries: eclipsing
更新于2025-09-23 15:23:52
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Thermal Infrared Imaging of MWC 758 with the Large Binocular Telescope: Planetary-driven Spiral Arms?
摘要： Theoretical studies suggest that a giant planet around the young star MWC 758 could be responsible for driving the spiral features in its circumstellar disk. Here, we present a deep imaging campaign with the Large Binocular Telescope with the primary goal of imaging the predicted planet. We present images of the disk in two epochs in the L′ filter (3.8 μm) and a third epoch in the M′ filter (4.8 μm). The two prominent spiral arms are detected in each observation, which constitute the first images of the disk at M′, and the deepest yet in L′ (ΔL′ = 12.1 exterior to the disk at 5σ significance). We report the detection of an S/N ～ 3.9 source near the end of the Southern arm, and, from the source’s detection at a consistent position and brightness during multiple epochs, we establish a ～90% confidence-level that the source is of astrophysical origin. We discuss the possibilities that this feature may be (a) an unresolved disk feature, and (b) a giant planet responsible for the spiral arms, with several arguments pointing in favor of the latter scenario. We present additional detection limits on companions exterior to the spiral arms, which suggest that a ?4 MJup planet exterior to the spiral arms could have escaped detection. Finally, we do not detect the companion candidate interior to the spiral arms reported recently by Reggiani et al., although forward modeling suggests that such a source would have likely been detected.
关键词： planets and satellites: formation,stars: pre-main sequence,planets and satellites: detection,planet–disk interactions
更新于2025-09-19 17:13:59