Three irradiated and bloated hot Jupiters West, R G; Hellier, C; Almenara, J-M ...
Astronomy and astrophysics (Berlin),
1/2016, Letnik:
585
Journal Article, Web Resource
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We report on three new transiting hot Jupiter planets, discovered from the WASP surveys, which we combine with radial velocities from OHP/SOPHIE and Euler/CORALIE and photometry from Euler and ...TRAPPIST. The planets WASP-76b, WASP-82b, and WASP-90b are all inflated, with radii of 1.7-1.8 R sub(Jup). All three orbit hot stars, of type F5-F7, with orbits of 1.8-3.9 d, and all three stars have evolved, post-main-sequence radii (1.7-2.2 R sub(middot in circle)). Thus the three planets fit a known trend of hot Jupiters that receive high levels of irradiation being highly inflated. We caution, though, about the presence of a selection effect, in that non-inflated planets around ~2 R sub(middot in circle) post-MS stars can often produce transits too shallow to be detected by the ground-based surveys that have found the majority of transiting hot Jupiters.
The CoRoT space mission observed 163 665 stars over 26 stellar fields in the faint star channel. The exoplanet teams detected a total of 4123 transit-like features in the 177 454 light curves. We ...present the complete re-analysis of all these detections carried out with the same softwares so that to ensure their homogeneous analysis. Although the vetting process involves some human evaluation, it also involves a simple binary flag system over basic tests: detection significance, presence of a secondary, difference between odd and even depths, colour dependence, V-shape transit, and duration of the transit. We also gathered the information from the large accompanying ground-based programme carried out on the planet candidates and checked how useful the flag system could have been at the vetting stage of the candidates. From the initial list of transit-like features, we identified and separated 824 false alarms of various kind, 2269 eclipsing binaries among which 616 are contact binaries and 1653 are detached ones, 37 planets and brown dwarfs, and 557 planet candidates. We provide the catalogue of all these transit-like features, including false alarms. For the planet candidates, the catalogue gives not only their transit parameters but also the products of their light curve modelling: reduced radius, reduced semi-major axis, and impact parameter, together with a summary of the outcome of follow-up observations when carried out and their current status. For the detached eclipsing binaries, the catalogue provides, in addition to their transit parameters, a simple visual classification. Among the planet candidates whose nature remains unresolved, we estimate that eight (within an error of three) planets are still to be identified. After correcting for geometric and sensitivity biases, we derived planet and brown dwarf occurrences and confirm disagreements with
Kepler
estimates, as previously reported by other authors from the analysis of the first runs: small-size planets with orbital period less than ten days are underabundant by a factor of three in the CoRoT fields whereas giant planets are overabundant by a factor of two. These preliminary results would however deserve further investigations using the recently released CoRoT light curves that are corrected of the various instrumental effects and a homogeneous analysis of the stellar populations observed by the two missions.
We present the radial-velocity follow-up of two Kepler planetary transiting candidates (KOI-189 and KOI-686) carried out with the SOPHIE spectrograph at the Observatoire de Haute Provence. These data ...promptly discard these objects as viable planet candidates and show that the transiting objects are in the regime of very low-mass stars, where a strong discrepancy between observations and models persists for the mass and radius parameters. By combining the SOPHIE spectra with the Kepler light curve and photometric measurements found in the literature, we obtain a full characterization of the transiting companions, their orbits, and their host stars. The two companions are in significantly eccentric orbits with relatively long periods (30 days and 52.5 days), which makes them suitable objects for a comparison with theoretical models, since the effects invoked to understand the discrepancy with observations are weaker for these orbital distances. KOI-189 b has a mass M = 0:0745 + or - 0:0033 M sub(middot in circle) and a radius R = 0:1025 + or - 0:0024 R sub(middot in circle). The density of KOI-189 b is significantly lower than expected from theoretical models for a system of its age. We explore possible explanations for this difference. KOI-189 b is the smallest hydrogen-burning star with such a precise determination of its fundamental parameters. KOI-686 b is larger and more massive (M = 0:0915 + or - 0:0043 M sub(middot in circle); R = 0:1201 + or - 0:0033 R sub(middot in circle)), and its position in the mass-radius diagram agrees well with theoretical expectations.
We observed the transit of the HAT-P-6b exoplanet across its host star with the SOPHIE spectrograph (OHP, France). The resulting stellar radial velocities display the Rossiter-McLaughlin anomaly and ...reveal a retrograde orbit: the planetary orbital spin and the stellar rotational spin point in approximately opposite directions. A fit to the anomaly measures a sky-projected angle λ = 166° ± 10° between these two spin axes. All seven known retrograde planets are hot Jupiters with masses Mp < 3 MJup. About two thirds of the planets in this mass range, however, are prograde and aligned (λ ≃ 0°). In contrast, most of the more massive planets (Mp > 4 MJup) are prograde but misaligned. Different mechanisms may therefore be responsible for planetary obliquities above and below ~3.5 MJup.
We present the detection and characterization of the transiting warm Jupiter KOI-12b, first identified with Kepler with an orbital period of 17.86 days. We combine the analysis of Kepler photometry ...with Doppler spectroscopy and line-profile tomography of time-series spectra obtained with the SOPHIE spectrograph to establish its planetary nature and derive its properties. To derive reliable estimates for the uncertainties on the tomographic model parameters, we devised an empirical method of calculating statistically independent error bars on the time-series spectra. KOI-12b has a radius of 1.43 + or - 0.13 R sub(Jup) and a 3sigma upper mass limit of 10 M sub(Jup). It orbits a fast-rotating star (vsinilow * = 60.0 + or - 0.9 km s super(-1)) with mass and radius of 1.45 + or - 0.09 M sub(middot in circle) and 1.63 + or -0.15 R sub(middot in circle), located at 426 + or - 40 pc from the Earth. Doppler tomography allowed higher precision on the obliquity to be reached by comparison with analysis of the Rossiter-McLaughlin radial velocity anomaly, and we find that KOI-12b lies on a prograde, slightly misaligned orbit with low sky-projected obliquity lambda = (ProQuest: Formulae and/or non-USASCII text omitted). The properties of this planetary system, with a 11.4 mag host star, make of KOI-12b a precious target for future atmospheric characterization.
We report the discovery of a long-period brown-dwarf transiting companion of the solar-type star KOI-415. The transits were detected by the Kepler space telescope. We conducted Doppler measurements ...using the SOPHIE spectrograph at the Observatoire de Haute-Provence. The photometric and spectroscopic signals allow us to characterize a 62.14 + or - 2.69 M sub(Jup) brown-dwarf companion of an evolved 0.94 + or - 0.06 Mmiddot in circle star in a highly eccentric orbit of P= 166.78805 + or - 0.00022 days and e = 0.698 + or - 0.002. The radius of KOI-415 b is 0.79 sub(-0.07) super(+0.12)R sub(Jup) , a value that is compatible with theoretical predictions for a 10 Gyr, low-metallicity and non-irradiated object.
Aims. Since 2011, the SOPHIE spectrograph has been used to search for Neptunes and super-Earths in the northern hemisphere. As part of this observational program, 290 radial velocity measurements of ...the 6.4 V magnitude star HD 158259 were obtained. Additionally, TESS photometric measurements of this target are available. We present an analysis of the SOPHIE data and compare our results with the output of the TESS pipeline.Methods. The radial velocity data, ancillary spectroscopic indices, and ground-based photometric measurements were analyzed with classical and ℓ1 periodograms. The stellar activity was modeled as a correlated Gaussian noise and its impact on the planet detection was measured with a new technique.Results. The SOPHIE data support the detection of five planets, each with m sin i ≈ 6 M⊕, orbiting HD 158259 in 3.4, 5.2, 7.9, 12, and 17.4 days. Though a planetary origin is strongly favored, the 17.4 d signal is classified as a planet candidate due to a slightly lower statistical significance and to its proximity to the expected stellar rotation period. The data also present low frequency variations, most likely originating from a magnetic cycle and instrument systematics. Furthermore, the TESS pipeline reports a significant signal at 2.17 days corresponding to a planet of radius ≈1.2 R⊕. A compatible signal is seen in the radial velocities, which confirms the detection of an additional planet and yields a ≈2 M⊕ mass estimate.Conclusions. We find a system of five planets and a strong candidate near a 3:2 mean motion resonance chain orbiting HD 158259. The planets are found to be outside of the two and three body resonances.
Context.
The impact of stellar mass on the properties of giant planets is still not fully understood. Main-sequence (MS) stars more massive than the Sun remain relatively unexplored in radial ...velocity (RV) surveys, due to their characteristics which hinder classical RV measurements.
Aims.
Our aim is to characterize the close (up to ~2 au) giant planet (GP) and brown dwarf (BD) population around AF MS stars and compare this population to stars with different masses.
Methods.
We used the S
OPHIE
spectrograph located on the 1.93 m telescope at Observatoire de Haute-Provence to observe 125 northern, MS AF dwarfs. We used our dedicated S
AFIR
software to compute the RV and other spectroscopic observables. We characterized the detected substellar companions and computed the GP and BD occurrence rates combining the present S
OPHIE
survey and a similar H
ARPS
survey.
Results.
We present new data on two known planetary systems around the F5-6V dwarfs HD 16232 and HD 113337. For the latter, we report an additional RV variation that might be induced by a second GP on a wider orbit. We also report the detection of 15 binaries or massive substellar companions with high-amplitude RV variations or long-term RV trends. Based on 225 targets observed with S
OPHIE
and/or H
ARPS
, we constrain the BD frequency within 2–3 au around AF stars to be below 4% (1
σ
). For Jupiter-mass GPs within 2–3 au (periods ≤10
3
days), we find the occurrence rate to be 3.7
−1
+3
% around AF stars with masses <1.5
M
⊙
, and to be ≤6% (1
σ
) around AF stars with masses >1.5
M
⊙
. For periods shorter than 10 days, we find the GP occurrence rate to be below 3 and 4.5% (1
σ
), respectively. Our results are compatible with the GP frequency reported around FGK dwarfs and are compatible with a possible increase in GP orbital periods with stellar mass as predicted by formation models.
ABSTRACT
SuperWASP, the Northern hemisphere WASP observatory, has been observing the skies from La Palma since 2004. In that time, more than 50 planets have been discovered with data contributions ...from SuperWASP. In the process of validating planets, many false-positive candidates have also been identified. The TESS telescope is set to begin observations of the northern sky in 2019. Similar to the WASP survey, the TESS pixel size is relatively large (13 arcsec for WASP and 21 arcsec for TESS), making it susceptible to many blended signals and false detections caused principally by grazing and blended stellar eclipsing binary systems. In order to reduce duplication of effort on targets, we present a catalogue of 1 041 Northern hemisphere SuperWASP targets that have been rejected as planetary transits through follow-up observation.
Periodic radial velocity variations in the nearby M-dwarf star Gl 411 are reported, based on measurements with the SOPHIE spectrograph. Current data do not allow us to distinguish between a 12.95-day ...period and its one-day alias at 1.08 days, but favour the former slightly. The velocity variation has an amplitude of 1.6 m s
−1
, making this the lowest-amplitude signal detected with SOPHIE up to now. We have performed a detailed analysis of the significance of the signal and its origin, including extensive simulations with both uncorrelated and correlated noise, representing the signal induced by stellar activity. The signal is significantly detected, and the results from all tests point to its planetary origin. Additionally, the presence of an additional acceleration in the velocity time series is suggested by the current data. On the other hand, a previously reported signal with a period of 9.9 days, detected in HIRES velocities of this star, is not recovered in the SOPHIE data. An independent analysis of the HIRES dataset also fails to unveil the 9.9-day signal. If the 12.95-day period is the real one, the amplitude of the signal detected with SOPHIE implies the presence of a planet, called Gl 411 b, with a minimum mass of around three Earth masses, orbiting its star at a distance of 0.079 AU. The planet receives about 3.5 times the insolation received by Earth, which implies an equilibrium temperature between 256 and 350 K, and makes it too hot to be in the habitable zone. At a distance of only 2.5 pc, Gl 411 b, is the third closest low-mass planet detected to date. Its proximity to Earth will permit probing its atmosphere with a combination of high-contrast imaging and high-dispersion spectroscopy in the next decade.
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