The first planet detected in the WTS: an inflated hot Jupiter in a 3.35 d orbit around a late F star
Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 427:3 (2012) 1877-1890
Discovery and characterization of detached M dwarf eclipsing binaries in the WFCAM transit survey
Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 426:2 (2012) 1507-1532
Abstract:
We report the discovery of 16 detached M dwarf eclipsing binaries with J < 16 mag and provide a detailed characterization of three of them, using high-precision infrared light curves from the WFCAM Transit Survey (WTS). Such systems provide the most accurate and model-independent method for measuring the fundamental parameters of these poorly understood yet numerous stars, which currently lack sufficient observations to precisely calibrate stellar evolution models. We fully solve for the masses and radii of three of the systems, finding orbital periods in the range 1.5 < P < 4.9 d, with masses spanning 0.35–0.50 M⊙ and radii between 0.38 and 0.50 R⊙, with uncertainties of ∼3.5–6.4 per cent in mass and ∼2.7–5.5 per cent in radius. Close companions in short-period binaries are expected to be tidally locked into fast rotational velocities, resulting in high levels of magnetic activity. This is predicted to inflate their radii by inhibiting convective flow and increasing starspot coverage. The radii of the WTS systems are inflated above model predictions by ∼3–12 per cent, in agreement with the observed trend, despite an expected lower systematic contribution from starspot signals at infrared wavelengths. We searched for correlation between the orbital period and radius inflation by combining our results with all existing M dwarf radius measurements of comparable precision, but we found no statistically significant evidence for a decrease in radius inflation for longer period, less active systems. Radius inflation continues to exists in non-synchronized systems, indicating that the problem remains even for very low activity M dwarfs. Resolving this issue is vital not only for understanding the most populous stars in the Universe, but also for characterizing their planetary companions, which hold the best prospects for finding Earth-like planets in the traditional habitable zone.Four ultra‐short‐period eclipsing M‐dwarf binaries in the WFCAM Transit Survey
Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 425:2 (2012) 950-968
The signature of orbital motion from the dayside of the planet τ Boötis b.
Nature 486:7404 (2012) 502-504
Abstract:
The giant planet orbiting τ Boötis (named τ Boötis b) was amongst the first extrasolar planets to be discovered. It is one of the brightest exoplanets and one of the nearest to us, with an orbital period of just a few days. Over the course of more than a decade, measurements of its orbital inclination have been announced and refuted, and have hitherto remained elusive. Here we report the detection of carbon monoxide absorption in the thermal dayside spectrum of τ Boötis b. At a spectral resolution of ∼100,000, we trace the change in the radial velocity of the planet over a large range in phase, determining an orbital inclination of 44.5° ± 1.5° and a mass 5.95 ± 0.28 times that of Jupiter, demonstrating that atmospheric characterization is possible for non-transiting planets. The strong absorption signal points to an atmosphere with a temperature that is decreasing towards higher altitudes, in contrast to the temperature inversion inferred for other highly irradiated planets. This supports the hypothesis that the absorbing compounds believed to cause such atmospheric inversions are destroyed in τ Boötis b by the ultraviolet emission from the active host star.Observational Constraints on Low-Mass Stellar Evolution and Planet Formation
(2011)