J140747.93−394542.6 Exhibits Evidence of Exomoons

Analysis of 1SWASP J140747.93−394542.6 eclipse fine-structure: hints of exomoons

Authors:

van Werkhoven et al

Abstract:

A recently discovered V = 12.3 mag K5 pre-main-sequence star in the SuperWASP (Super Wide Angle Search for Planets) data base shows a peculiar light curve with a highly structured eclipse pattern covering a timespan of at least 54 d with maximum dimming of at least 3.3 mag. The central eclipse is surrounded by two 1 mag eclipses at ±12 and ±26 d. The authors speculate that the star is eclipsed by a substellar companion with an extended and highly structured ring system. To investigate the nightly light-curve structure and to confirm the multiple-ring hypothesis, we have carried out a calibrated reduction of the SuperWASP data, removing both systematic errors and periodic stellar variability. We count at least 24 inflection points on ingress and 16 on egress, consistent with the presence of at least 24 rings in this disc. By measuring the light-curve slope, we find implied speeds for the eclipsing object that are incompatible with a closed Kepler orbit with P = 2.3 yr. We propose several scenarios that could give rise to such light-curve slopes and find that azimuthal ring structure (analogous to ‘spokes’ seen in Saturn's rings) can account for the observed light curve. The highly structured ring system also implies the presence of exomoons orbiting the secondary companion.

SuperWASP Provides Evidence of Circumbinary Exoplanets

Period and amplitude variations in post-common-envelope eclipsing binaries observed with SuperWASP

Authors:

Lohr et al

Abstract:

Period or amplitude variations in eclipsing binaries may reveal the presence of additional massive bodies in the system, such as circumbinary planets. Here, we have studied twelve previously-known eclipsing post-common-envelope binaries for evidence of such light curve variations, on the basis of multi-year observations in the SuperWASP archive. The results for HW Vir provided strong evidence for period changes consistent with those measured by previous studies, and help support a two-planet model for the system. ASAS J102322-3737.0 exhibited plausible evidence for a period increase not previously suggested; while NY Vir, QS Vir and NSVS 14256825 afforded less significant support for period change, providing some confirmation to earlier claims. In other cases, period change was not convincingly observed; for AA Dor and NSVS 07826147, previous findings of constant period were confirmed. This study allows us to present hundreds of new primary eclipse timings for these systems, and further demonstrates the value of wide-field high-cadence surveys like SuperWASP for the investigation of variable stars.