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Register a new userAn Exo-Jupiter Candidate in the Eclipsing Binary FL Lyr
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Light curves of the eclipsing binary FL Lyr acquired by the Kepler space telescope are analyzed. Eclipse timing measurements for FL Lyr testify to the presence of a third body in the system. Preliminary estimates of its mass and orbital period are > 4M_Jupiter and > 7 yrs. The times of primary minimum in the light curve of FL Lyr during the operation of the Kepler mission are presented.
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We present the results of an analysis of data covering 1.5 years of the dwarf nova V447 Lyr. We detect eclipses of the accretion disk by the mass donating secondary star every 3.74 hrs which is the binary orbital period. V447 Lyr is therefore the first dwarf nova in the Kepler field to show eclipses. We also detect five long outbursts and six short outbursts showing V447 Lyr is a U Gem type dwarf nova. We show that the orbital phase of the mid-eclipse occurs earlier during outbursts compared to quiescence and that the width of the eclipse is greater during outburst. This suggests that the bright spot is more prominent during quiescence and that the disk is larger during outburst than quiescence. This is consistent with an expansion of the outer disk radius due to the presence of high viscosity material associated with the outburst, followed by a contraction in quiescence due to the accretion of low angular momentum material. We note that the long outbursts appear to be triggered by a short outburst, which is also observed in the super-outbursts of SU UMa dwarf novae as observed using Kepler.
Mass, radius, and age are three of the most fundamental parameters for celestial objects, enabling studies of the evolution and internal physics of stars, brown dwarfs, and planets. Brown dwarfs are hydrogen-rich objects that are unable to sustain core fusion reactions but are supported from collapse by electron degeneracy pressure. As they age, brown dwarfs cool, reducing their radius and luminosity. Young exoplanets follow a similar behaviour. Brown dwarf evolutionary models are relied upon to infer the masses, radii and ages of these objects. Similar models are used to infer the mass and radius of directly imaged exoplanets. Unfortunately, only sparse empirical mass, radius and age measurements are currently available, and the models remain mostly unvalidated. Double-line eclipsing binaries provide the most direct route for the absolute determination of the masses and radii of stars. Here, we report the SPECULOOS discovery of 2M1510A, a nearby, eclipsing, double-line brown dwarf binary, with a widely-separated tertiary brown dwarf companion. We also find that the system is a member of the $45pm5$ Myr-old moving group, Argus. The systems age matches those of currently known directly-imaged exoplanets. 2M1510A provides an opportunity to benchmark evolutionary models of brown dwarfs and young planets. We find that widely-used evolutionary models do reproduce the mass, radius and age of the binary components remarkably well, but overestimate the luminosity by up to 0.65 magnitudes, which could result in underestimated photometric masses for directly-imaged exoplanets and young field brown dwarfs by 20 to 35%.
We present the discovery of only the third brown dwarf known to eclipse a non-accreting white dwarf. Gaia parallax information and multi-colour photometry confirm that the white dwarf is cool (9950$pm$150K) and has a low mass (0.45$pm$0.05~MSun), and spectra and lightcurves suggest the brown dwarf has a mass of 0.067 $pm$0.006 MSun (70 MJup) and a spectral type of L5 $pm$1. The kinematics of the system show that the binary is likely to be a member of the thick disk and therefore at least 5 Gyr old. The high cadence lightcurves show that the brown dwarf is inflated, making it the first brown dwarf in an eclipsing white dwarf-brown dwarf binary to be so.
Removing outbursts from multiwavelength light curves of the blazar Mrk~421, we construct outburstless time series for this system. A model-independent power spectrum light curve analysis in the optical, hard X-ray and gamma-rays for this outburstless state and also the full light-curves, show clear evidence for a periodicity of ~ 310 days across all wavelengths studied. A subsequent full maximum likelihood analysis fitting an eclipse model confirms a periodicity of 310 pm 1 days. The power spectrum of the signal in the outburstless state of the source does not follow a flicker noise behaviour and so, the system producing it is not self-organised. This and the fact that the periodicity is better defined in the outburstless state, strongly suggests that it is not produced by any internal physical processes associated to the central engine. The simplest physical mechanism to which this periodicity could be ascribed is a dynamical effect produced by an orbiting supermassive black hole companion eclipsing the central engine. Interestingly, the optimal eclipse model infers a brightness enhancement of (136.4 pm 20 )%, suggesting an eclipse resulting in a gravitational lensing brightening. Consisting with this interpretation, the eclipse occurs for only ( 9.7 pm 0.2)% of the orbital period.
We present the discovery with WISE of a significant infrared excess associated with the eclipsing post-common envelope binary SDSSJ 030308.35+005443.7, the first excess discovered around a non-interacting white dwarf+main sequence M dwarf binary. The spectral energy distribution of the white dwarf+M dwarf companion shows significant excess longwards of 3-microns. A T_eff of 8940K for the white dwarf is consistent with a cooling age >2 Gyr, implying that the excess may be due to a recently formed circumbinary dust disk of material that extends from the tidal truncation radius of the binary at 1.96 Rsun out to <0.8 AU, with a total mass of ~10^20 g. We also construct WISE and follow-up ground-based near-infrared light curves of the system, and find variability in the K-band that appears to be in phase with ellipsoidal variations observed in the visible. The presence of dust might be due to a) material being generated by the destruction of small rocky bodies that are being perturbed by an unseen planetary system or b) dust condensing from the companions wind. The high inclination of this system, and the presence of dust, make it an attractive target for M dwarf transit surveys and long term photometric monitoring.
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