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.
We present new eclipse observations for one of the hottest ‘hot Jupiters', WASP-18b, for which previously published data from HST WFC3 and Spitzer have led to radically conflicting conclusions about ...the composition of this planet’s atmosphere. We measure eclipse depths of 0.15 ± 0.02 per cent at Ks and 0.07 ± 0.01 per cent at z′ bands. Using the VSTAR line-by-line radiative transfer code and both these new observations with previously published data, we derive a new model of the planetary atmosphere. We have varied both the metallicity and C/O ratio in our modelling, and find no need for the extreme metallicity suggested by Sheppard et al. Our best-fitting models slightly underestimate the emission at z′ band and overestimate the observed flux at Ks-band. To explain these discrepancies, we examine the impact on the planetary emission spectrum of the presence of several types of hazes which could form on the night side of the planet. Our Ks-band eclipse flux measurement is lower than expected from clear atmosphere models and this could be explained by haze particles larger than 0.2 μm with the optical properties of Al2O3, CaTiO3 or MgSiO3. We find that z′-band measurements are important for understanding the contribution of photochemical hazes with particles smaller than 0.1 μm at the top of the atmosphere.
Aims. We present new calculations of limb and gravity-darkening coefficients to be used as input in many fields of stellar physics such as synthetic light curves of double-lined eclipsing binaries ...and planetary transits, studies of stellar diameters or line profiles in rotating stars. Methods. We compute the limb-darkening coefficients specifically for the photometric system of the satellite MOST (Microvariability and Oscillations in STars). All computations were performed by adopting the least-square method, but for completeness we also performed calculations for the linear and bi-parametric approaches by adopting the flux conservation method. The passband gravity-darkening coefficients y(λ) were computed by adopting a more general differential equation, which also takes the effects of convection into account. Results. We used two stellar atmosphere models: ATLAS (plane-parallel) and PHOENIX (spherical and quasi-spherical). We adopted six laws to describe the specific intensity distribution: linear, quadratic, square root, logarithmic, exponential, and a more general one with four terms. The covered ranges of Teff, log g, metallicities, and microturbulent velocities are (1500–50 000 K, 0–5.5, −5.0–+1.0, 0–8 km s-1), respectively.
Food waste is a social, environmental, and economic challenge today. The European Union’s Green Deal demands tackling this problem. Our research question is: “What are the solutions regarding food ...waste prevention across the companies’ supply chain?” The mixed research method consisted of content and thematic analysis. We collected information from the reports published by European food companies that have joined the Green Deal and the Farm to Fork Strategy. The data were structured using a theoretical model in which we integrated ten essential stages of the food chain. The findings show that most of the information is reported for the manufacturing/production stage. Although transfer to landfill is unavoidable in supply chains, organizations make substantial efforts to reduce the proportion of food waste. The methods applied by food companies are inspired by European regulations regarding environmental protection. Our research identifies solutions brought about by the Green Deal on food waste prevention.
We present the discovery and characterization of a transiting sub-Neptune that orbits the nearby (28 pc) and bright (
V
= 8.37) K0V star HD 207897 (TOI-1611) with a 16.20-day period. This discovery ...is based on photometric measurements from the Transiting Exoplanet Survey Satellite mission and radial velocity (RV) observations from the SOPHIE, Automated Planet Finder, and HIRES high-precision spectrographs. We used EXOFASTv2 to model the parameters of the planet and its host star simultaneously, combining photometric and RV data to determine the planetary system parameters. We show that the planet has a radius of 2.50 ± 0.08
R
E
and a mass of either 14.4 ± 1.6
M
E
or 15.9 ± 1.6
M
E
with nearly equal probability. The two solutions correspond to two possibilities for the stellar activity period. The density accordingly is either 5.1 ± 0.7 g cm
−3
or 5.5
−0.7
+0.8
g cm
−3
, making it one of the relatively rare dense sub-Neptunes. The existence of this dense planet at only 0.12 AU from its host star is unusual in the currently observed sub-Neptune (2 <
R
E
< 4) population. The most likely scenario is that this planet has migrated to its current position.
The Transiting Exoplanet Survey Satellite (TESS) provides a continuous suite of new planet candidates that need confirmation and precise mass determination from ground-based observatories. This is ...the case for the G-type star TOI-1710, which is known to host a transiting sub-Saturn planet (Mp = 28.3 ± 4.7 M⊕) in a long-period orbit (P = 24.28 days). Here we combine archival SOPHIE and new and archival HARPS-N radial velocity data with newly available TESS data to refine the planetary parameters of the system and derive a new mass measurement for the transiting planet, taking into account the impact of the stellar activity on the mass measurement. We report for TOI-1710b a radius of Rp = 5.15 ± 0.12 R⊕, a mass of Mp = 18.4 ± 4.5 M⊕, and a mean bulk density of ρp = 0.73 ± 0.18 g cm−3, which are consistent at 1.2σ, 1.5σ, and 0.7σ, respectively, with previous measurements. Although there is not a significant difference in the final mass measurement, we needed to add a Gaussian process component to successfully fit the radial velocity dataset. This work illustrates that adding more measurements does not necessarily imply a better mass determination in terms of precision, even though they contribute to increasing our full understanding of the system. Furthermore, TOI-1710b joins an intriguing class of planets with radii in the range 4–8 R⊕ that have no counterparts in the Solar System. A large gaseous envelope and a bright host star make TOI-1710b a very suitable candidate for follow-up atmospheric characterization.
Circumstellar environment of 55 Cancri Folsom, C P; Fionnagáin, D Ó; Fossati, L ...
Astronomy and astrophysics (Berlin),
01/2020, Letnik:
633
Journal Article
Recenzirano
Odprti dostop
Context. 55 Cancri hosts five known exoplanets, most notably the hot super-Earth 55 Cnc e, which is one of the hottest known transiting super-Earths. Aims. Because of the short orbital separation and ...host star brightness, 55 Cnc e provides one of the best opportunities for studying star-planet interactions (SPIs). We aim to understand possible SPIs in this system, which requires a detailed understanding of the stellar magnetic field and wind impinging on the planet. Methods. Using spectropolarimetric observations and Zeeman Doppler Imaging, we derived a map of the large-scale stellar magnetic field. We then simulated the stellar wind starting from the magnetic field map, using a 3D magneto-hydrodynamic model. Results. The map of the large-scale stellar magnetic field we derive has an average strength of 3.4 G. The field has a mostly dipolar geometry; the dipole is tilted by 90° with respect to the rotation axis and the dipolar strength is 5.8 G at the magnetic pole. The wind simulations based on this magnetic geometry lead us to conclude that 55 Cnc e orbits inside the Alfvén surface of the stellar wind, implying that effects from the planet on the wind can propagate back to the stellar surface and result in SPI.
The reconstruction of aneurysm geometry is a main factor affecting the accuracy of hemodynamics simulations in patient-specific aneurysms. We analyzed the effects of the inlet artery length on ...intra-aneurysmal flow estimations by using 10 ophthalmic aneurysm models.
We successively truncated the inlet artery of each model, first at the cavernous segment and second at the clinoid segment. For each aneurysm, we obtained 3 models with different artery lengths: the originally segmented geometry with the longest available inlet from scans and 2 others with successively shorter artery lengths. We analyzed the velocity, wall shear stress, and the oscillatory shear index inside the aneurysm and compared the 2 truncations with the original model.
We found that eliminating 1 arterial turn resulted in root mean square errors of <18% with no visual differences for the contours of the flow parameters in 8 of the 10 models. In contrast, truncating at the second turn led to root mean square errors between 18% and 32%, with consistently large errors for wall shear stress and the oscillatory shear index in 5 of the 10 models and visual differences for the contours of the flow parameters. For 3 other models, the largest errors were between 43% and 55%, with large visual differences in the contour plots.
Excluding 2 arterial turns from the inlet artery length of the ophthalmic aneurysm resulted in large quantitative differences in the calculated velocity, wall shear stress, and oscillatory shear index distributions, which could lead to erroneous conclusions if used clinically.
Health disparities are differences in health status across different socioeconomic groups. Classical methods, e.g., the Delta method, have been used to estimate the standard errors of estimated ...measures of health disparities and to construct confidence intervals for these measures. However, the confidence intervals constructed using the classical methods do not have good coverage properties for situations involving sparse data. In this article, we introduce three new methods to construct fiducial intervals for measures of health disparities based on approximate fiducial quantities. Through a comprehensive simulation study, We compare the empirical coverage properties of the proposed fiducial intervals against two Monte Carlo simulation-based methods-utilizing either a truncated Normal distribution or the Gamma distribution-as well as the classical method. The findings of the simulation study advocate for the adoption of the Monte Carlo simulation-based method with the Gamma distribution when a unified approach is sought for all health disparity measures.
The United Nations Sustainable Development Goals (UN SDGs) were introduced in 2015 to advance the 2030 Agenda of sustainable development in all supporting countries. The SDGs are applicable to ...countries, non-governmental organizations, industries, and companies. In this article, we focus on the contribution of listed companies headquartered in the European Union (EU) to the SDGs. The EU intends to be the front-runner in the race for sustainable development and has adopted comprehensive strategies that mirror the UN SDGs. For this reason, we collected relevant data points from the Refinitiv Eikon database for 1156 companies headquartered in EU countries for the financial year 2022. The data collected refer to contributions to each SDG and the adoption of corporate sustainability policies. Data were statistically analyzed per country and sector to generate a comprehensive image of industry contributions to the SDGs in the EU. By applying a comparative analysis of country-level achievements and policies, the results point to four EU countries that are significant contributors to the SDGs through their economic activities. At the same time, other EU countries are still facing significant challenges in this domain. The socioeconomic considerations for these cases are laid out in the Discussion section. The present article offers a snapshot of corporate contributions to the SDGs as climate and geopolitical challenges become more prominent.
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