We present the discovery by the WASP-South survey of WASP-121 b, a new remarkable short-period transiting hot Jupiter. The planet has a mass of
$1.183_{-0.062}^{+0.064}$
M
Jup, a radius of 1.865 ± ...0.044 R
Jup, and transits every
$1.274\,9255_{-0.000\,0025}^{+0.000\,0020}$
days an active F6-type main-sequence star (V = 10.4,
$1.353_{-0.079}^{+0.080}$
M⊙, 1.458 ± 0.030 R⊙, T
eff = 6460 ± 140 K). A notable property of WASP-121 b is that its orbital semimajor axis is only ∼1.15 times larger than its Roche limit, which suggests that the planet is close to tidal disruption. Furthermore, its large size and extreme irradiation (∼7.1 109 erg s−1 cm−2) make it an excellent target for atmospheric studies via secondary eclipse observations. Using the TRAnsiting Planets and PlanetesImals Small Telescope, we indeed detect its emission in the z
′-band at better than ∼4σ, the measured occultation depth being 603 ± 130 ppm. Finally, from a measurement of the Rossiter–McLaughlin effect with the CORALIE spectrograph, we infer a sky-projected spin-orbit angle of
$257{^{\circ}_{.}} 8_{-5{^{\circ}_{.}} 5}^{+5{^{\circ}_{.}} 3}$
. This result may suggest a significant misalignment between the spin axis of the host star and the orbital plane of the planet. If confirmed, this high misalignment would favour a migration of the planet involving strong dynamical events with a third body.
We describe seven exoplanets transiting stars of brightness V = 10.1-12.4. WASP-130b is a 'warm Jupiter' having an orbital period of 11.6 d around a metal-rich G6 star. Its mass and radius (1.23 plus ...or minus 0.04 M sub( Jup) and 0.89 plus or minus 0.03 R sub( Jup)) support the trend that warm Jupiters have smaller radii than hot Jupiters. WASP-131b is a bloated Saturn-mass planet (0.27 M sub( Jup) and 1.22 R sub( Jup)). Its large scaleheight and bright (V = 10.1) host star make it a good target for atmospheric characterization. WASP-132b (0.41 M sub( Jup) and 0.87 R sub( Jup)) is among the least irradiated and coolest of WASP planets, having a 7.1-d orbit around a K4 star. WASP-139b is a 'super-Neptune' akin to HATS-7b and HATS-8b, being the lowest mass planet yet found by WASP (0.12 M sub( Jup) and 0.80 R sub( Jup)). The metal-rich K0 host star appears to be anomalously dense, akin to HAT-P-11. WASP-140b is a 2.4-M sub( Jup) planet in an eccentric (e = 0.047 plus or minus 0.004) 2.2-d orbit. The planet's radius is large (1.4 R sub( Jup)), but uncertain owing to the grazing transit (b = 0.93). The 10.4-d rotation period of the K0 host star suggests a young age, and the time-scale for tidal circularization is likely to be the lowest of all known eccentric hot Jupiters. WASP-141b (2.7 M sub( Jup), 1.2 R sub( Jup) and P = 3.3 d) and WASP-142b (0.84 M sub( Jup), 1.53 R sub( Jup) and P = 2.1 d) are typical hot Jupiters orbiting metal-rich F stars. We show that the period distribution within the hot-Jupiter bulge does not depend on the metallicity of the host star.
The abundance and properties of planets orbiting binary stars – circumbinary planets – are largely unknown because they are difficult to detect with currently available techniques. Results from the ...Kepler satellite and other studies indicate a minimum occurrence rate of circumbinary giant planets of ∼10 per cent, yet only a handful are presently known. Here, we study the potential of ESA's Gaia mission to discover and characterize extrasolar planets orbiting nearby binary stars by detecting the binary's periodic astrometric motion caused by the orbiting planet. We expect that Gaia will discover hundreds of giant planets around binaries with FGK-dwarf primaries within 200 pc of the Sun, if we assume that the giant planet mass distribution and abundance are similar around binaries and single stars. If on the other hand all circumbinary gas giants have masses lower than two Jupiter masses, we expect only four detections. Gaia is critically sensitive to the properties of giant circumbinary planets and will therefore make the detailed study of their population possible. Gaia's precision is such that the distribution in mutual inclination between the binary and planetary orbital planes will be obtained. It also possesses the capacity to establish the frequency of planets across the Hertzsprung-Russell diagram, both as a function of mass and of stellar evolutionary state from pre-main sequence to stellar remnants. Gaia's discoveries can reveal whether a second epoch of planetary formation occurs after the red giant phase.
We report the discovery of the transiting exoplanets WASP-69b, WASP-70Ab and WASP-84b, each of which orbits a bright star (V ~ 10). WASP-69b is a bloated Saturn-mass planet (0.26 MJup, 1.06 RJup) in ...a 3.868-d period around an active, ~1-Gyr, mid-K dwarf. ROSAT detected X-rays 60 plus or minus 27 arcsec from WASP-69. If the star is the source then the planet could be undergoing mass-loss at a rate of ~10... g s-1. This is one to two orders of magnitude higher than the evaporation rate estimated for HD 209458b and HD 189733b, both of which have exhibited anomalously large Lyman ... absorption during transit. WASP-70Ab is a sub-Jupiter-mass planet (0.59 MJup, 1.16 RJup) in a 3.713-d orbit around the primary of a spatially resolved, 9-10-Gyr, G4+K3 binary, with a separation of 3.3 arcsec ( greater than or equal to 800 au). WASP-84b is a sub-Jupiter-mass planet (0.69 MJup, 0.94 RJup) in an 8.523-d orbit around an active, ~1-Gyr, early-K dwarf. Of the transiting planets discovered from the ground to date, WASP-84b has the third-longest period. For the active stars WASP-69 and WASP-84, we pre-whitened the radial velocities using a low-order harmonic series. We found that this reduced the residual scatter more than did the oft-used method of pre-whitening with a fit between residual radial velocity and bisector span. The system parameters were essentially unaffected by pre-whitening. (ProQuest: ... denotes formulae/symbols omitted.)
The young (∼16 Myr) pre-main-sequence star in Sco–Cen 1SWASP J140747.93−394542.6, hereafter referred to as J1407, underwent a deep eclipse in 2007 April, bracketed by several shallower eclipses in ...the surrounding 54 d. This has been interpreted as the first detection of an eclipsing ring system circling a substellar object (dubbed J1407b). We report on a search for this companion with Sparse Aperture Mask imaging and direct imaging with both the UT4 VLT and Keck telescopes. Radial velocity measurements of J1407 provide additional constraints on J1407b and on short period companions to the central star. Follow-up photometric monitoring using the Panchromatic Robotic Optical Monitoring and Polarimetry Telescopes (PROMPT)-4 and ROAD observatories during 2012–2014 has not yielded any additional eclipses. Large regions of mass–period space are ruled out for the companion. For circular orbits the companion period is constrained to the range 3.5–13.8 yr (a ≃ 2.2–5.6 au), and stellar masses (>80M
Jup) are ruled out at 3σ significance over these periods. The complex ring system appears to occupy more than 0.15 of its Hill radius, much larger than its Roche radius and suggesting a ring structure in transition. Further, we demonstrate that the radial velocity of J1407 is consistent with membership in the Upper Cen–Lup subgroup of the Sco–Cen association, and constraints on the rotation period and projected rotational velocity of J1407 are consistent with a stellar inclination of i
⋆ ≃ 68° ± 10°.
We present an efficient analytical method to predict the maximum transit timing variations of a circumbinary exoplanet, given some basic parameters of the host binary. We derive an analytical model ...giving limits on the potential location of transits for coplanar planets orbiting eclipsing binaries, then test it against numerical N-body simulations of a distribution of binaries and planets. We also show the application of the analytic model to Kepler-16b, -34b and -35b. The resulting method is fast, efficient and is accurate to approximately 1 per cent in predicting limits on possible times of transits over a 3-yr observing campaign. The model can easily be used to, for example, place constraints on transit timing while performing circumbinary planet searches on large data sets. It is adaptable to use in situations where some or many of the planet and binary parameters are unknown.
We present the discovery of three new transiting giant planets, first detected with the WASP telescopes, and establish their planetary nature with follow up spectroscopy and ground-based photometric ...light curves. WASP-92 is an F7 star, with a moderately inflated planet orbiting with a period of 2.17 d, which has R sub( p) = 1.461 plus or minus 0.077R sub( J) and M sub( p) = 0.805 plus or minus 0.068M sub( J). WASP-93b orbits its F4 host star every 2.73 d and has R sub( p) = 1.597 plus or minus 0.077R sub( J) and M sub( p) = 1.47 plus or minus 0.029M sub( J). WASP-118b also has a hot host star (F6) and is moderately inflated, where R sub( p) = 1.440 plus or minus 0.036R sub( J) and M sub( p) = 0.514 plus or minus 0.020M sub( J) and the planet has an orbital period of 4.05 d. They are bright targets (V = 13.18, 10.97 and 11.07, respectively) ideal for further characterization work, particularly WASP-118b, which is being observed by K2 as part of campaign 8. The WASP-93 system has sufficient angular momentum to be tidally migrating outwards if the system is near spin-orbit alignment, which is divergent from the tidal behaviour of the majority of hot Jupiters discovered.
We report detection of thermal emission from the exoplanet WASP-19b at 3.6, 4.5, 5.8 and 8.0 μm. We used the InfraRed Array Camera on the Spitzer Space Telescope to observe two occultations of ...WASP-19b by its host star. We combine our new detections with previous measurements of WASP-19b's emission at 1.6 and 2.09 μm to construct a spectral energy distribution of the planet's dayside atmosphere. By comparing this with model-atmosphere spectra, we find that the dayside atmosphere of WASP-19b lacks a strong temperature inversion. As WASP-19 is an active star (log R'HK = -4.50 ± 0.03), this finding supports the hypothesis of Knutson, Howard and Isaacson that inversions are suppressed in hot Jupiters orbiting active stars. The available data are unable to differentiate between a carbon-rich and an oxygen-rich atmosphere. PUBLICATION ABSTRACT
Transits on single stars are rare. The probability rarely exceeds a few per cent. Furthermore, this probability rapidly approaches zero at increasing orbital period. Therefore, transit surveys have ...been predominantly limited to the inner parts of exoplanetary systems. Here, we demonstrate how circumbinary planets allow us to beat these unfavourable odds. By incorporating the geometry and the three-body dynamics of circumbinary systems, we analytically derive the probability of transitability, a configuration where the binary and planet orbits overlap on the sky. We later show that this is equivalent to the transit probability, but at an unspecified point in time. This probability, at its minimum, is always higher than for single star cases. In addition, it is an increasing function with mutual inclination. By applying our analytical development to eclipsing binaries, we deduce that transits are highly probable, and in some case guaranteed. For example, a circumbinary planet revolving at 1 au around a 0.3 au eclipsing binary is certain to eventually transit – a 100 per cent probability – if its mutual inclination is greater than 0
$_{.}^{\circ}$
6. We show that the transit probability is generally only a weak function of the planet's orbital period; circumbinary planets may be used as practical tools for probing the outer regions of exoplanetary systems to search for and detect warm to cold transiting planets.
Planet formation theories predict a large but still undetected population of short-period terrestrial planets orbiting brown dwarfs. Should specimens of this population be discovered transiting ...relatively bright and nearby brown dwarfs, the Jupiter-size and the low luminosity of their hosts would make them exquisite targets for detailed atmospheric characterization with JWST and future ground-based facilities. The eventual discovery and detailed study of a significant sample of transiting terrestrial planets orbiting nearby brown dwarfs could prove to be useful not only for comparative exoplanetology but also for astrobiology, by bringing us key information on the physical requirements and time-scale for the emergence of life. In this context, we present a search for transit-signals in archival time series photometry acquired by the Spitzer Space Telescope for a sample of 44 nearby brown dwarfs. While these 44 targets were not particularly selected for their brightness, the high precision of their Spitzer light curves allows us to reach sensitivities below Earth-sized planets for 75 per cent of the sample and down to Europa-sized planets on the brighter targets. We could not identify any unambiguous planetary signal. Instead, we could compute the first limits on the presence of planets on close-in orbits. We find that within a 1.28 d orbit, the occurrence rate of planets with a radius between 0.75 and 3.25 R... is ... < 67 plus or minus 1 per cent. For planets with radii between 0.75 and 1.25 R..., we place a 95 per cent confident upper limit of ... < 87 plus or minus 3 per cent. If we assume an occurrence rate of ... = 27 per cent for these planets with radii between 0.75 and 1.25 R..., as the discoveries of the Kepler-42b and TRAPPIST-1b systems would suggest, we estimate that 175 brown dwarfs need to be monitored in order to guarantee (95 per cent) at least one detection. (ProQuest: ... denotes formulae/symbols omitted.)
PDF
