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- ID:
- ivo://CDS.VizieR/J/MNRAS/506/3810
- Title:
- 7 transiting exoplanets CHEOPS light curves
- Short Name:
- J/MNRAS/506/3810
- Date:
- 03 Dec 2021 00:34:45
- Publisher:
- CDS
- Description:
- We present 17 transit light curves of seven known warm-Jupiters observed with the CHaracterising ExOPlanet Satellite (CHEOPS). The light curves have been collected as part of the CHEOPS Guaranteed Time Observation (GTO) program that searches for transit-timing variation (TTV) of warm-Jupiters induced by a possible external perturber to shed light on the evolution path of such planetary systems. We describe the CHEOPS observation process, from the planning to the data analysis. In this work we focused on the timing performance of CHEOPS, the impact of the sampling of the transit phases, and the improvement we can obtain combining multiple transits together. We reached the highest precision on the transit time of about 13-16s for the brightest target (WASP-38, G=9.2) in our sample. From the combined analysis of multiple transits of fainter targets with G>=11 we obtained a timing precision of ~2min. Additional observations with CHEOPS, covering a longer temporal baseline, will further improve the precision on the transit times and will allow us to detect possible TTV signals induced by an external perturber.
- ID:
- ivo://CDS.VizieR/J/ApJ/809/77
- Title:
- Transiting Exoplanet Survey Satellite (TESS)
- Short Name:
- J/ApJ/809/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Transiting Exoplanet Survey Satellite (TESS) is a NASA-sponsored Explorer mission that will perform a wide-field survey for planets that transit bright host stars. Here, we predict the properties of the transiting planets that TESS will detect along with the EB stars that produce false-positive photometric signals. The predictions are based on Monte Carlo simulations of the nearby population of stars, occurrence rates of planets derived from Kepler, and models for the photometric performance and sky coverage of the TESS cameras. We expect that TESS will find approximately 1700 transiting planets from 2x10^5^ pre-selected target stars. This includes 556 planets smaller than twice the size of Earth, of which 419 are hosted by M dwarf stars and 137 are hosted by FGK dwarfs. Approximately 130 of the R<2R_{Earth}_ planets will have host stars brighter than Ks=9. Approximately 48 of the planets with R<2R_{Earth}_ lie within or near the habitable zone (0.2<S/S_{Earth}_<2); between 2 and 7 such planets have host stars brighter than Ks=9. We also expect approximately 1100 detections of planets with radii 2-4R_{Earth}_, and 67 planets larger than 4R_{Earth}_. Additional planets larger than 2R_{Earth}_ can be detected around stars that are not among the pre-selected target stars, because TESS will also deliver full-frame images at a 30-minute cadence. The planet detections are accompanied by over 1000 astrophysical false positives. We discuss how TESS data and ground-based observations can be used to distinguish the false positives from genuine planets. We also discuss the prospects for follow-up observations to measure the masses and atmospheres of the TESS planets.
- ID:
- ivo://CDS.VizieR/J/MNRAS/428/678
- Title:
- Transiting exoplanet TrES-3b CCD UBVR photometry
- Short Name:
- J/MNRAS/428/678
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed nine primary transits of the hot Jpiter TrES-3b in several optical and near-UV photometric bands from 2009 June to 2012 April in an attempt to detect its magnetic field. Vidotto, Jardine and Helling suggest that the magnetic field of TrES-3b can be constrained if its near-UV light curve shows an early ingress compared to its optical light curve, while its egress remains unaffected. Predicted magnetic field strengths of Jupiter-like planets should range between 8G and 30G. Using these magnetic field values and an assumed B* of 100G, the Vidotto et al. method predicts a timing difference of 5-11min. We did not detect an early ingress in our three nights of near-UV observations, despite an average cadence of 68 s and an average photometric precision of 3.7mmag. However, we determined an upper limit of TrES-3b's magnetic field strength to range between 0.013 and 1.3G (for a 1-100G magnetic field strength range for the host star, TrES-3) using a timing difference of 138s derived from the Nyquist-Shannon sampling theorem. To verify our results of an abnormally small magnetic field strength for TrES-3b and to further constrain the techniques of Vidotto et al., we propose future observations of TrES-3b with other platforms capable of achieving a shorter near-UV cadence. We also present a refinement of the physical parameters of TrES-3b, an updated ephemeris and its first published near-UV light curve. We find that the near-UV planetary radius of Rp=1.386+0.248-0.144RJup is consistent with the planet's optical radius.
- ID:
- ivo://CDS.VizieR/J/ApJ/649/1043
- Title:
- Transiting extrasolar planet HD 209458b
- Short Name:
- J/ApJ/649/1043
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured the infrared transit of the extrasolar planet HD 209458b using the Spitzer Space Telescope. We observed two primary eclipse events (one partial and one complete transit) using the 24um array of the Multiband Imaging Photometer for Spitzer (MIPS). We analyzed a total of 2392 individual images (10s integrations) of the planetary system, recorded before, during, and after transit. We performed optimal photometry on the images and used the local zodiacal light as a short-term flux reference. At this long wavelength, the transit curve has a simple boxlike shape, allowing robust solutions for the stellar and planetary radii independent of stellar limb darkening, which is negligible at 24um. We derive a stellar radius of R*=(1.06+/-0.07)R_{sun}_, a planetary radius of Rp=(1.26+/-0.08)R_J_, and a stellar mass of 1.17M_{sun}_. Within the errors, our results agree with the measurements at visible wavelengths. The 24um radius of the planet therefore does not differ significantly compared to the visible result. We point out the potential for deriving extrasolar transiting planet radii to high accuracy using transit photometry at slightly shorter IR wavelengths where greater photometric precision is possible.
- ID:
- ivo://CDS.VizieR/J/A+A/553/A44
- Title:
- Transiting extrasolar planet WASP-33b
- Short Name:
- J/A+A/553/A44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HD 15082 (WASP-33) is the hottest and fastest rotating star known to harbor a transiting extrasolar planet (WASP-33b) The lack of high precision radial velocity (RV) data stresses the need for precise light curve analysis and gathering further RV data. By using available photometric and RV data, we perform a blend analysis, compute more accurate system parameters, confine the planetary mass and attempt to cast light on the observed transit anomalies. We combine the original HATNet observations and various followup data to jointly analyze the signal content and extract the transit component and use our RV data to aid the global parameter determination. The blend analysis of the combination of multicolor light curves yields the first independent confirmation of the planetary nature of WASP-33b. We clearly identify three frequency components in the 15-21c/d regime with amplitudes 5-7mmag. These frequencies correspond to the delta Scuti-type pulsation of the host star. None of these pulsation frequencies or their low-order linear combinations are in close resonance with the orbital frequency. We show that these pulsation components explain some but not all of the observed transit anomalies. The grand-averaged transit light curve shows that there is a ~1.5mmag brightening shortly after the planet passes the mid-transit phase. Although the duration and amplitude of this brightening varies, it is visible even through the direct inspections of the individual transit events (some 40-60% of the followup light curves show this phenomenon). We suggest that the most likely explanation of this feature is the presence of a well-populated spot belt which is highly inclined to the orbital plane. This geometry is consistent with the inference from the spectroscopic anomalies. Finally, we constrain the planetary mass to M_p_=3.27+/-0.73M_J_ by using our RV data collected by the TRES spectrograph.
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/2831
- Title:
- 4 transiting F-M binary systems
- Short Name:
- J/MNRAS/437/2831
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of four transiting F-M binary systems with companions between 0.1 and 0.2M_{sun}_ in mass by the HATSouth survey. These systems have been characterized via a global analysis of the HATSouth discovery data, combined with high-resolution radial velocities and accurate transit photometry observations. We determined the masses and radii of the component stars using a combination of two methods: isochrone fitting of spectroscopic primary star parameters and equating spectroscopic primary star rotation velocity with spin-orbit synchronization. These new very low mass companions are HATS550-016B (0.110_-0.006_^+0.005^M_{sun}_, 0.147_-0.004_^+0.003^R_{sun}_), HATS551-019B (0.17_-0.01_^+0.01^M_sun}_, 0.18_-0.01_^+0.01^R_{sun}_), HATS551-021B (0.132_-0.005_^+0.014^M_sun}_, 0.154_-0.008_^+0.006^R_{sun}_) and HATS553-001B (0.20_-0.02_^+0.01^M_sun}_, 0.22_-0.01_^+0.01^R_{sun}_). We examine our sample in the context of the radius anomaly for fully convective low-mass stars. Combining our sample with the 13 other well-studied very low mass stars, we find a tentative 5 percent systematic deviation between the measured radii and theoretical isochrone models.
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/1338
- Title:
- Transiting planetary system WASP-17
- Short Name:
- J/MNRAS/426/1338
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometric observations of four transits in the WASP-17 planetary system, obtained using telescope defocusing techniques and with scatters reaching 0.5mmag per point. Our revised orbital period is 4.0+/-0.6s longer than previous measurements, a difference of 6.6{sigma}, and does not support the published detections of orbital eccentricity in this system. We model the light curves using the JKTEBOP code and calculate the physical properties of the system by recourse to five sets of theoretical stellar model predictions. The resulting planetary radius, Rb=1.932+/-0.052+/-0.010R_Jup_ (statistical and systematic errors, respectively), provides confirmation that WASP-17b is the largest planet currently known. All 14 planets with radii measured to be greater than 1.6R_Jup_are found around comparatively hot (T_eff_>5900K) and massive (M_A_>1.15M_{sun}_) stars. Chromospheric activity indicators are available for eight of these stars, and all imply a low activity level. The planets have small or zero orbital eccentricities, so tidal effects struggle to explain their large radii.
- ID:
- ivo://CDS.VizieR/J/MNRAS/399/287
- Title:
- Transiting planetary system WASP-4
- Short Name:
- J/MNRAS/399/287
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present and analyse light curves of four transits of the Southern hemisphere extrasolar planetary system WASP-4, obtained with a telescope defocussed so the radius of each point spread function was 17 arcsec (44 pixels). This approach minimises both random and systematic errors, allowing us to achieve scatters of between 0.60 and 0.88mmag per observation over complete transit events. The light curves are augmented by published observations and analysed using the JKTEBOP code. The results of this process are combined with theoretical stellar model predictions to derive the physical properties of the WASP-4 system. WASP-4 is now one of the best-quantified transiting extrasolar planetary systems, and significant further progress requires improvements to our understanding of the physical properties of low-mass stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/396/1023
- Title:
- Transiting planetary system WASP-5
- Short Name:
- J/MNRAS/396/1023
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-precision photometry of two transit events of the extrasolar planetary system WASP-5, obtained with the Danish 1.54m telescope at ESO La Silla. In order to minimise both random and flat-fielding errors, we defocussed the telescope so its point spread function approximated an annulus of diameter 40 pixels (16 arcsec). Data reduction was undertaken using standard aperture photometry plus an algorithm for optimally combining the ensemble of comparison stars. The resulting light curves have point-to- point scatters of 0.50mmag for the first transit and 0.59mmag for the second. We construct detailed signal to noise calculations for defocussed photometry, and apply them to our observations. We model the light curves with the JKTEBOP code and combine the results with tabulated predictions from theoretical stellar evolutionary models to derive the physical properties of the WASP-5 system.
