238 research outputs found
Efeito de doses de gesso agrícola e alterações químicas ocorridas no perfil do solo em sistema de plantio direto consolidado cultivado com soja.
O Plantio direto é uma prática que vem sendo utilizada com frequência na última década, devido as melhorias que este sistema pode trazer as características físico-químicas do solo
Exploiting timing capabilities of the CHEOPS mission with warm-Jupiter planets
Funding: ACC and TGW acknowledge support from STFC consolidated grant No. ST/M001296/1. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (project FOUR ACES; grant agreement No. 724427)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 by combining multiple transits together. We reached the highest precision on the transit time of about 13–16 s 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 ∼2 min. 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.Publisher PDFPeer reviewe
CHEOPS geometric albedo of the hot Jupiter HD 209458 b
Funding: P.F.L.M. acknowledges support from STFC research grant number ST/M001040/1. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (project Four Aces. grant agreement No 724427).We report the detection of the secondary eclipse of the hot Jupiter HD 209458 b in optical/visible light using the CHEOPS space telescope. Our measurement of 20.4-3.3+3.2 parts per million translates into a geometric albedo of Ag = 0.096 ± 0.016. The previously estimated dayside temperature of about 1500 K implies that our geometric albedo measurement consists predominantly of reflected starlight and is largely uncontaminated by thermal emission. This makes the present result one of the most robust measurements of Ag for any exoplanet. Our calculations of the bandpassintegrated geometric albedo demonstrate that the measured value of Ag is consistent with a cloud-free atmosphere, where starlight is reflected via Rayleigh scattering by hydrogen molecules, and the water and sodium abundances are consistent with stellar metallicity. We predict that the bandpass-integrated TESS geometric albedo is too faint to detect and that a phase curve of HD 209458 b observed by CHEOPS would have a distinct shape associated with Rayleigh scattering if the atmosphere is indeed cloud free.Publisher PDFPeer reviewe
Analysis of Early Science observations with the CHaracterising ExOPlanets Satellite (CHEOPS) using pycheops
Funding: ACC and TW acknowledge support from UK Science and Technologies Facilities Council (STFC) ST/R00824/1.CHEOPS (CHaracterising ExOPlanet Satellite) is an ESA S-class mission that observes bright stars at high cadence from low-Earth orbit. The main aim of the mission is to characterize exoplanets that transit nearby stars using ultrahigh precision photometry. Here we report the analysis of transits observed by CHEOPS during its Early Science observing programme for four well-known exoplanets: GJ 436 b, HD 106315 b, HD 97658 b and GJ 1132 b. The analysis is done using pycheops, an open-source software package we have developed to easily and efficiently analyse CHEOPS light curve data using state-of-the-art techniques that are fully described herein. We show that the precision of the transit parameters measured using CHEOPS is comparable to that from larger space telescopes such as Spitzer Space Telescope and Kepler. We use the updated planet parameters from our analysis to derive new constraints on the internal structure of these four exoplanets.PostprintPeer reviewe
Detection of the tidal deformation of WASP-103b at 3 σ with CHEOPS
Funding: A.C.C. and T.G.W. acknowledge support from STFC consolidated grant number ST/M001296/1.Context. Ultra-short period planets undergo strong tidal interactions with their host star which lead to planet deformation and orbital tidal decay. Aims: WASP-103b is the exoplanet with the highest expected deformation signature in its transit light curve and one of the shortest expected spiral-in times. Measuring the tidal deformation of the planet would allow us to estimate the second degree fluid Love number and gain insight into the planet's internal structure. Moreover, measuring the tidal decay timescale would allow us to estimate the stellar tidal quality factor, which is key to constraining stellar physics. Methods: We obtained 12 transit light curves of WASP-103b with the CHaracterising ExOplanet Satellite (CHEOPS) to estimate the tidal deformation and tidal decay of this extreme system. We modelled the high-precision CHEOPS transit light curves together with systematic instrumental noise using multi-dimensional Gaussian process regression informed by a set of instrumental parameters. To model the tidal deformation, we used a parametrisation model which allowed us to determine the second degree fluid Love number of the planet. We combined our light curves with previously observed transits of WASP-103b with the Hubble Space Telescope (HST) and Spitzer to increase the signal-to-noise of the light curve and better distinguish the minute signal expected from the planetary deformation. Results: We estimate the radial Love number of WASP-103b to be hf =1.59-0.53+0.45. This is the first time that the tidal deformation is directly detected (at 3 σ) from the transit light curve of an exoplanet. Combining the transit times derived from CHEOPS, HST, and Spitzer light curves with the other transit times available in the literature, we find no significant orbital period variation for WASP-103b. However, the data show a hint of an orbital period increase instead of a decrease, as is expected for tidal decay. This could be either due to a visual companion star if this star is bound, the Applegate effect, or a statistical artefact. Conclusions: The estimated Love number of WASP-103b is similar to Jupiter's. This will allow us to constrain the internal structure and composition of WASP-103b, which could provide clues on the inflation of hot Jupiters. Future observations with James Webb Space Telescope can better constrain the radial Love number of WASP-103b due to their high signal-to-noise and the smaller signature of limb darkening in the infrared. A longer time baseline is needed to constrain the tidal decay in this system. The transit light curves are only available at the CDS via anonymous ftpt o cdsarc.u-strasbg.fr(ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/657/A52.Publisher PDFPeer reviewe
CHEOPS and TESS view of the ultra-short period super-Earth TOI-561 b
Ultra-short period planets (USPs) are a unique class of super-Earths with an
orbital period of less than a day and hence subject to intense radiation from
their host star. While most of them are consistent with bare rocks, some show
evidence of a heavyweight envelope, which could be a water layer or a secondary
metal-rich atmosphere sustained by an outgassing surface. Much remains to be
learned about the nature of USPs. The prime goal of the present work is to
study the bulk planetary properties and atmosphere of TOI-561b, through the
study of its transits and occultations. We obtained ultra-precise transit
photometry of TOI-561b with CHEOPS and performed a joint analysis of this data
with four TESS sectors. Our analysis of TOI-561b transit photometry put strong
constraints on its properties, especially on its radius, Rp=1.42 +/- 0.02
R_Earth (at ~2% error). The internal structure modelling of the planet shows
that the observations are consistent with negligible H/He atmosphere, however
requiring other lighter materials, in addition to pure iron core and silicate
mantle to explain the observed density. We find that this can be explained by
the inclusion of a water layer in our model. We searched for variability in the
measured Rp/R* over time to trace changes in the structure of the planetary
envelope but none found within the data precision. In addition to the transit
event, we tentatively detect occultation signal in the TESS data with an
eclipse depth of ~27 +/- 11 ppm. Using the models of outgassed atmospheres from
the literature we find that the thermal emission from the planet can mostly
explain the observation. Based on this, we predict that NIR/MIR observations
with JWST should be able to detect silicate species in the atmosphere of the
planet. This could also reveal important clues about the planetary interior and
help disentangle planet formation and evolution models.Comment: 17 pages, 10 + 3 figures, 4 tables, accepted for publication in A&A
(abstract abbreviated
Constraining the reflective properties of WASP-178b using Cheops photometry
Multiwavelength photometry of the secondary eclipses of extrasolar planets is
able to disentangle the reflected and thermally emitted light radiated from the
planetary dayside. This leads to the measurement of the planetary geometric
albedo , which is an indicator of the presence of clouds in the
atmosphere, and the recirculation efficiency , which quantifies the
energy transport within the atmosphere. In this work we aim to measure
and for the planet WASP-178 b, a highly irradiated giant planet with
an estimated equilibrium temperature of 2450 K.} We analyzed archival spectra
and the light curves collected by Cheops and Tess to characterize the host
WASP-178, refine the ephemeris of the system and measure the eclipse depth in
the passbands of the two respective telescopes. We measured a marginally
significant eclipse depth of 7040 ppm in the Tess passband and
statistically significant depth of 7020 ppm in the Cheops passband.
Combining the eclipse depth measurement in the Cheops (lambda_eff=6300 AA) and
Tess (lambda_eff=8000 AA) passbands we constrained the dayside brightness
temperature of WASP-178 b in the 2250-2800 K interval. The geometric albedo
0.1<<0.35 is in general agreement with the picture of poorly
reflective giant planets, while the recirculation efficiency 0.7
makes WASP-178 b an interesting laboratory to test the current heat
recirculation models.Comment: Accepted by Astronomy and Astrophysics on 31/08/202
Transit timing variations of AU Microscopii b and c
Funding: A.C.C. and T.W. acknowledge support from STFC consolidated grant number ST/M001296/1.Here we report large-amplitude transit timing variations (TTVs) for AU Microcopii b and c as detected in combined TESS (2018, 2020) and CHEOPS (2020, 2021) transit observations. AU Mic is a young planetary system with a debris disk and two transiting warm Neptunes. A TTV on the order of several minutes was previously reported for AU Mic b, which was suggested to be an outcome of mutual perturbations between the planets in the system. In 2021, we observed AU Mic b (five transits) and c (three transits) with the CHEOPS space telescope to follow-up the TTV of AU Mic b and possibly detect a TTV for AU Mic c. When analyzing TESS and CHEOPS 2020-2021 measurements together, we find that a prominent TTV emerges with a full span of >= 23 min between the two TTV extrema. Assuming that the period change results from a periodic process -such as mutual perturbations- we demonstrate that the times of transits in the summer of 2022 are expected to be 30-85 min later than predicted by the available linear ephemeris.Publisher PDFPeer reviewe
55 Cancri e's occultation captured with CHEOPS
Past occultation and phase-curve observations of the ultra-short period
super-Earth 55 Cnc e obtained at visible and infrared wavelengths have been
challenging to reconcile with a planetary reflection and emission model. In
this study, we analyse a set of 41 occultations obtained over a two-year
timespan with the CHEOPS satellite. We report the detection of 55 Cnc e's
occultation with an average depth of ppm. We derive a corresponding
2- upper limit on the geometric albedo of once
decontaminated from the thermal emission measured by Spitzer at 4.5m.
CHEOPS's photometric performance enables, for the first time, the detection of
individual occultations of this super-Earth in the visible and identifies
short-timescale photometric corrugations likely induced by stellar granulation.
We also find a clear 47.3-day sinusoidal pattern in the time-dependent
occultation depths that we are unable to relate to stellar noise, nor
instrumental systematics, but whose planetary origin could be tested with
upcoming JWST occultation observations of this iconic super-Earth.Comment: In press. Accepted for publication in Astronomy and Astrophysics on
13 October 2022. 10 pages, 7 figures and 3 table
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