Context. 55 Cnc e is a transiting super-Earth orbiting a solar-like star with an orbital period of ~17.7 h. In 2011, using the Microvariability and Oscillations in Stars (MOST) space telescope, a ...quasi-sinusoidal modulation in flux was detected with the same period as the planetary orbit. The amplitude of this modulation was too large to be explained as the change in light reflected or emitted by the planet. Aims. The MOST telescope continued to observe 55 Cnc e for a few weeks per year over five years (from 2011 to 2015), covering 143 individual transits. This paper presents the analysis of the observed phase modulation throughout these observations and a search for the secondary eclipse of the planet. Methods. The most important source of systematic noise in MOST data is due to stray-light reflected from the Earth, which is modulated with both the orbital period of the satellite (101.4 min) and the Earth’s rotation period. We present a new technique to deal with this source of noise, which we combined with standard detrending procedures for MOST data. We then performed Markov chain Monte Carlo analyses of the detrended light curves, modeling the planetary transit and phase modulation. Results. We find phase modulations similar to those seen in 2011 in most of the subsequent years; however, the amplitude and phase of maximum light are seen to vary, from year to year, from 113 to 28 ppm and from 0.1 to 3.8 rad. The secondary eclipse is not detected, but we constrain the geometric albedo of the planet to less than 0.47 (2σ). Conclusions. While we cannot identify a single origin of the observed optical modulation, we propose a few possible scenarios. Those include star-planet interaction, such as coronal rains and spots rotating with the motion of the planet along its orbit, or the presence of a transiting circumstellar torus of dust. However, a detailed interpretation of these observations is limited by their photometric precision. Additional observations at optical wavelengths could measure the variations at higher precision, contribute to uncovering the underlying physical processes, and measure or improve the upper limit on the albedo of the planet.
WASP-80b: a gas giant transiting a cool dwarf Triaud, A. H. M. J.; Anderson, D. R.; Collier Cameron, A. ...
Astronomy & astrophysics,
03/2013, Letnik:
551
Journal Article, Web Resource
Recenzirano
Odprti dostop
We report the discovery of a planet transiting the star WASP-80 (1SWASP J201240.26-020838.2; 2MASS J20124017-0208391; TYC 5165-481-1; BPM 80815; V = 11.9, K = 8.4). Our analysis shows this is a ...0.55 ± 0.04 Mjup, 0.95 ± 0.03 Rjup gas giant on a circular 3.07 day orbit around a star with a spectral type between K7V and M0V. This system produces one of the largest transit depths so far reported, making it a worthwhile target for transmission spectroscopy. We find a large discrepancy between the vsini⋆ inferred from stellar line broadening and the observed amplitude of the Rossiter-McLaughlin effect. This can be understood either by an orbital plane nearly perpendicular to the stellar spin or by an additional, unaccounted for source of broadening.
We report on the discovery of GJ 3470 b, a transiting hot Uranus of mass mp = 14.0 ± 1.8 M⊕, radius Rp = 4.2 ± 0.6 R⊕ and period P = 3.3371 ± 0.0002 day. Its host star is a nearby (d = 25.2 ± 2.9 pc) ...M1.5 dwarf of mass M⋆ = 0.54 ± 0.07 M⊙ and radius R⋆ = 0.50 ± 0.06 R⊙. The detection was made during a radial-velocity campaign with Harps that focused on the search for short-period planets orbiting M dwarfs. Once the planet was discovered and the transit-search window narrowed to about 10% of an orbital period, a photometric search started with Trappist and quickly detected the ingress of the planet. Additional observations with Trappist, EulerCam and Nites definitely confirmed the transiting nature of GJ 3470b and allowed the determination of its true mass and radius. The star's visible or infrared brightness (Vmag = 12.3, Kmag = 8.0), together with a large eclipse depth D = 0.57 ± 0.05%, ranks GJ 3470 b among the most suitable planets for follow-up characterizations. Based on observations made with the HARPS instrument on the ESO 3.6 m telescope under the program IDs 183.C-0437 at Cerro La Silla (Chile).Our radial-velocity and photometric time series are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/546/A27
ABSTRACT
We present the discovery of three transiting planets from the WASP survey, two hot-Jupiters: WASP-177 b (∼0.5 MJup, ∼1.6 RJup) in a 3.07-d orbit of a V = 12.6 K2 star, WASP-183 b (∼0.5 MJup, ...∼1.5 RJup) in a 4.11-d orbit of a V = 12.8 G9/K0 star; and one hot-Saturn planet WASP-181 b (∼0.3 MJup, ∼1.2 RJup) in a 4.52-d orbit of a V = 12.9 G2 star. Each planet is close to the upper bound of mass–radius space and has a scaled semimajor axis, a/R*, between 9.6 and 12.1. These lie in the transition between systems that tend to be in orbits that are well aligned with their host-star’s spin and those that show a higher dispersion.
Since 1998, a planet-search program around main sequence stars within 50 pc in the southern hemisphere has been carried out with the CORALIE echelle spectrograph at La Silla Observatory. With an ...observing time span of more than 14 years, the CORALIE survey is now able to unveil Jovian planets on Jupiter's period domain. This growing period-interval coverage is important for building formation and migration models since observational constraints are still weak fir periods beyond the ice line. Long-term, precise Doppler measurements with the CORALIE echelle spectrograph, together with a few additional observations made with the HARPS spectrograph on the ESO 3.6m telescope, reveal radial velocity signatures of massive planetary companions on long-period orbits. In this paper we present seven new planets orbiting HD27631, HD98649, HD 106515A, HD166724, HD196067, HD219077, and HD220689, together with the CORALIE orbital parameters for three already known planets around HD10647, HD30562, and HD86226. Finally, the hosts of these long period planets show no metallicity excess.
The K2-33 planetary system hosts one transiting ~5 R⊕ planet orbiting the young M-type host star. The planet’s mass is still unknown, with an estimated upper limit of 5.4 MJ. The extreme youth of the ...system (<20 Myr) gives the unprecedented opportunity to study the earliest phases of planetary evolution, at a stage when the planet is exposed to an extremely high level of high-energy radiation emitted by the host star. We perform a series of 1D hydrodynamic simulations of the planet’s upper atmosphere considering a range of possible planetary masses, from 2 to 40 M⊕, and equilibrium temperatures, from 850 to 1300 K, to account for internal heating as a result of contraction. We obtain temperature profiles mostly controlled by the planet’s mass, while the equilibrium temperature has a secondary effect. For planetary masses below 7–10 M⊕, the atmosphere is subject to extremely high escape rates, driven by the planet’s weak gravity and high thermal energy, which increase with decreasing mass and/or increasing temperature. For higher masses, the escape is instead driven by the absorption of the high-energy stellar radiation. A rough comparison of the timescales for complete atmospheric escape and age of the system indicates that the planet is more massive than 10 M⊕.
We report the discovery of eight hot-Jupiter exoplanets from the WASP-South transit survey. WASP-144b has a mass of 0.44 MSUBJup/SUB, a radius of 0.85 RSUBJup/SUB, and is in a 2.27-d orbit around a V ...= 12.9, K2 star which shows a 21-d rotational modulation. WASP-145Ab is a 0.89 MSUBJup/SUB planet in a 1.77-d orbit with a grazing transit. The host is a V = 11.5, K2 star with a companion 5 arcsec away and 1.4 mag fainter. WASP-158b is a relatively massive planet at 2.8 MSUBJup/SUB with a radius of 1.1 RSUBJup/SUB and a 3.66-d orbit. It transits a V = 12.1, F6 star. WASP-159b is a bloated hot Jupiter (1.4 RSUBJup/SUB and 0.55 MSUBJup/SUB) in a 3.8-d orbit around a V = 12.9, F9 star. WASP-162b is a massive planet in a relatively long and highly eccentric orbit (5.2 MSUBJup/SUB, P = 9.6 d, e = 0.43). It transits a V = 12.2, K0 star. WASP-168b is a bloated hot Jupiter (0.42 MSUBJup/SUB; 1.5 RSUBJup/SUB) in a 4.15-d orbit with a grazing transit. The host is a V = 12.1, F9 star. WASP-172b is a bloated hot Jupiter (0.5 MSUBJup/SUB; 1.6 RSUBJup/SUB) in a 5.48-d orbit around a V = 11.0, F1 star. WASP-173Ab is a massive planet (3.7 MSUBJup/SUB) with a 1.2 RSUBJup/SUB radius in a circular orbit with a period of 1.39 d. The host is a V = 11.3, G3 star, being the brighter component of the double-star system WDS23366 - 3437, with a companion 6 arcsec away and 0.8 mag fainter. One of the two stars shows a rotational modulation of 7.9 d.
We report the discovery of four transiting hot Jupiters, WASP-147, WASP-160B, WASP-164 and WASP-165 from the WASP survey. WASP-147b is a near Saturn-mass (MSUBP/SUB = 0.28MSUBJ/SUB) object with a ...radius of 1.11 RSUBJ/SUB orbiting a G4 star with a period of 4.6 d. WASP-160Bb has a mass and radius (MSUBp/SUB = 0.28 MSUBJ/SUB, RSUBp/SUB = 1.09 RSUBJ/SUB) near-identical to WASP-147b, but is less irradiated, orbiting a metal-rich (Fe/HSUB*/SUB = 0.27) K0 star with a period of 3.8 d. WASP-160B is part of a near equal-mass visual binary with an on-sky separation of 28.5 arcsec. WASP-164b is a more massive (MSUBP/SUB = 2.13 MSUBJ/SUB, RSUBp/SUB = 1.13 RSUBJ/SUB) hot Jupiter, orbiting a G2 star on a close-in (P = 1.8 d), but tidally stable orbit. WASP-165b is a classical (MSUBp/SUB = 0.66 MSUBJ/SUB, RSUBP/SUB = 1.26 RSUBJ/SUB) hot Jupiter in a 3.5 d period orbit around a metal-rich (Fe/HSUB*/SUB = 0.33) star. WASP-147b and WASP-160Bb are promising targets for atmospheric characterization through transmission spectroscopy, while WASP-164b presents a good target for emission spectroscopy.
We report the discovery of the low-density, transiting giant planet WASP-31b. The planet is 0.48 Jupiter masses and 1.55 Jupiter radii. It is in a 3.4-day orbit around a metal-poor, late-F-type, ...V = 11.7 dwarf star, which is a member of a common proper motion pair. In terms of its low density, WASP-31b is second only to WASP-17b, which is a more highly irradiated planet of similar mass.
Context. Ground-based simultaneous multiband transit observations allow an accurate system parameter determination and may lead to the detection and characterization of additional bodies via the ...transit timing variations (TTVs) method. Aims. We aim to (i) characterize the heavily bloated WASP-4b hot Jupiter and its star by measuring system parameters and the dependence of the planetary radius as a function of four (Sloan g′, r′, i′, z′) wavelengths and (ii) search for TTVs. Methods. We recorded 987 images during three complete transits with the GROND instrument, mounted on the MPG/ESO-2.2 m telescope at La Silla Observatory. Assuming a quadratic law for the stellar limb-darkening, we derived the system parameters by simultaneous fitting a composite transit light curve over all bandpasses. To compute uncertainties of the fitted parameters, we employed the bootstrap Monte Carlo method. Results. The three central transit times are measured with precision down to 6 s. We find a planetary radius Rp = 1.413 ± 0.020 RJup, an orbital inclination \hbox{$i = 88\fdg 57 \pm 0.45^{\circ}$}i=88.°57±0.45◦ and calculate a new ephemeris, a period P = 1.33823144 ± 0.00000032 days and a reference transit epoch T0 = 2 454 697.798311 ± 0.000046 (BJD). Analysis of the new transit mid-times in combination with previous measurements shows no sign of a TTV signal greater than 20 s. We perform simplified numerical simulations to place upper-mass limits of a hypothetical perturber in the WASP-4b system.
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