The Transiting Exoplanet Survey Satellite (TESS) recently observed 18 transits of the hot Jupiter WASP-4b. The sequence of transits occurred 81.6 11.7 s earlier than had been predicted, based on data ...stretching back to 2007. This is unlikely to be the result of a clock error, because TESS observations of other hot Jupiters (WASP-6b, 18b, and 46b) are compatible with a constant period, ruling out an 81.6 s offset at the 6.4 level. The 1.3 day orbital period of WASP-4b appears to be decreasing at a rate of ms per year. The apparent period change might be caused by tidal orbital decay or apsidal precession, although both interpretations have shortcomings. The gravitational influence of a third body is another possibility, though at present there is minimal evidence for such a body. Further observations are needed to confirm and understand the timing variation.
Stellar interiors are inaccessible through direct observations. For this reason, helioseismologists made use of the Sun's acoustic oscillation modes to tune models of its structure. The quest to ...detect modes that probe the solar core has been ongoing for decades. We report the detection of mixed modes penetrating all the way to the core of an evolved star from 320 days of observations with the Kepler satellite. The period spacings of these mixed modes are directly dependent on the density gradient between the core region and the convective envelope.
Context.
Prominences in the solar atmosphere represent an intriguing and delicate balance of forces and thermodynamics in an evolving magnetic topology. How this relatively cool material comes to ...reside at coronal heights, and what drives its evolution prior to, during, and after its appearance, remains an area full of open questions.
Aims.
We here set forth to identify the physical processes driving the formation and evolution of prominence condensations within 2.5D magnetic flux ropes. We deliberately focus on the levitation-condensation scenario, where a coronal flux rope forms and eventually demonstrates in situ condensations, revisiting it at extreme resolutions down to order 6 km in scale.
Methods.
We perform grid-adaptive numerical simulations in a 2.5D translationally invariant setup, where we can study the distribution of all metrics involved in advanced magnetohydrodynamic stability theory for nested flux rope equilibria. We quantify in particular convective continuum instability (CCI), thermal instability (TI), baroclinicity, and mass-slipping metrics within a series of numerical simulations of prominences formed via levitation-condensation.
Results.
Overall, we find that the formation and evolution of prominence condensations happens in a clearly defined sequence regardless of resolution, with background field strength between 3 and 10 Gauss. The CCI governs the slow evolution of plasma prior to the formation of distinct condensations found to be driven by the TI. Evolution of the condensations towards the topological dips of the magnetic flux rope is a consequence of these condensations initially forming out of pressure balance with their surroundings. From the baroclinicity distributions, smaller-scale rotational motions are inferred within forming and evolving condensations. Upon the complete condensation of a prominence ‘monolith’, the slow descent of this plasma towards lower heights appears consistent with the mass-slippage mechanism driven by episodes of both local current diffusion and magnetic reconnection.
We report the discovery of TOI 837b and its validation as a transiting planet. We characterize the system using data from the NASA Transiting Exoplanet Survey Satellite mission, the ESA Gaia mission, ...ground-based photometry from El Sauce and ASTEP400, and spectroscopy from CHIRON, FEROS, and Veloce. We find that TOI 837 is a T = 9.9 mag G0/F9 dwarf in the southern open cluster IC 2602. The star and planet are therefore million years old. Combining the transit photometry with a prior on the stellar parameters derived from the cluster color-magnitude diagram, we find that the planet has an orbital period of and is slightly smaller than Jupiter ( ). From radial velocity monitoring, we limit to less than 1.20 MJup (3 ). The transits either graze or nearly graze the stellar limb. Grazing transits are a cause for concern, as they are often indicative of astrophysical false-positive scenarios. Our follow-up data show that such scenarios are unlikely. Our combined multicolor photometry, high-resolution imaging, and radial velocities rule out hierarchical eclipsing binary scenarios. Background eclipsing binary scenarios, though limited by speckle imaging, remain a 0.2% possibility. TOI 837b is therefore a validated adolescent exoplanet. The planetary nature of the system can be confirmed or refuted through observations of the stellar obliquity and the planetary mass. Such observations may also improve our understanding of how the physical and orbital properties of exoplanets change in time.
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► Vibrational spectrum of PET complicated by the presence of rotational isomers and changes on crystallization. ► Synchronous and asynchronous correlation spectra enables the ...absorption bands to be unambiguously assigned. ► Fractional crystallinity can be directly determined from the amorphous and crystalline band ratio.
The vibrational spectrum of partially crystalline poly(ethylene terephthalate), PET, appears to be unduly complex in that the absorption bands are split into amorphous and crystalline modes and are sensitive to chain configuration and orientation. Assignment of the bands has accordingly proved to be difficult and lead to differences in interpretation. Two-dimensional infrared spectroscopy is a recent novel analytical technique in vibrational spectroscopy which can be used to interpret differences in the spectra with time or temperature accompanying changes in structure and morphology and has been used to analyze the development of crystallinity within a polymer in which amorphous regions are transformed into crystalline regions and involving changes in molecular configuration.
Two-dimensional IR correlation spectroscopy has been successfully applied to these problems in the attempt to measure the fractional extent of crystallinity in PET as a function of time and crystallization temperature as well as changes to molecular configuration.
Context.
We report the discovery of TOI 263.01 (TIC 120916706), a transiting substellar object (
R
= 0.87
R
Jup
) orbiting a faint M3.5 V dwarf (
V
= 18.97) on a 0.56 d orbit.
Aims.
We setout to ...determine the nature of the Transiting Exoplanet Survey Satellite (TESS) planet candidate TOI 263.01 using ground-based multicolour transit photometry. The host star is faint, which makes radial-velocity confirmation challenging, but the large transit depth makes the candidate suitable for validation through multicolour photometry.
Methods.
Our analysis combines three transits observed simultaneously in
r
′,
i
′, and
z
s
bands usingthe MuSCAT2 multicolour imager, three LCOGT-observed transit light curves in
g
′,
r
′, and
i
′ bands, a TESS light curve from Sector 3, and a low-resolution spectrum for stellar characterisation observed with the ALFOSC spectrograph. We modelled the light curves with P
Y
T
RANSIT
using a transit model that includes a physics-based light contamination component, allowing us to estimate the contamination from unresolved sources from the multicolour photometry. Using this information we were able to derive the true planet–star radius ratio marginalised over the contamination allowed by the photometry.Combining this with the stellar radius, we were able to make a reliable estimate of the absolute radius of the object.
Results.
The ground-based photometry strongly excludes contamination from unresolved sources with a significant colour difference to TOI 263. Furthermore, contamination from sources of the same stellar type as the host is constrained to levels where the true radius ratio posterior has a median of 0.217 and a 99 percentile of0.286. The median and maximum radius ratios correspond to absolute planet radii of 0.87 and 1.41
R
Jup
, respectively,which confirms the substellar nature of the planet candidate. The object is either a giant planetor a brown dwarf (BD) located deep inside the so-called “brown dwarf desert”. Both possibilities offer a challenge to current planet/BD formation models and make TOI 263.01 an object that merits in-depth follow-up studies.
Aims/hypothesis Dietary non-oil-seed pulses (chickpeas, beans, peas, lentils, etc.) are a good source of slowly digestible carbohydrate, fibre and vegetable protein and a valuable means of lowering ...the glycaemic-index (GI) of the diet. To assess the evidence that dietary pulses may benefit glycaemic control, we conducted a systematic review and meta-analysis of randomised controlled experimental trials investigating the effect of pulses, alone or as part of low-GI or high-fibre diets, on markers of glycaemic control in people with and without diabetes. Methods We searched MEDLINE, EMBASE, CINAHL, and the Cochrane Library for relevant controlled trials of >=7 days. Two independent reviewers (A. Esfahani and J. M. W. Wong) extracted information on study design, participants, treatments and outcomes. Data were pooled using the generic inverse variance method and expressed as standardised mean differences (SMD) with 95% CIs. Heterogeneity was assessed by χ ² and quantified by I ². Meta-regression models identified independent predictors of effects. Results A total of 41 trials (39 reports) were included. Pulses alone (11 trials) lowered fasting blood glucose (FBG) (-0.82, 95% CI -1.36 to -0.27) and insulin (-0.49, 95% CI -0.93 to -0.04). Pulses in low-GI diets (19 trials) lowered glycosylated blood proteins (GP), measured as HbA₁c or fructosamine (-0.28, 95% CI -0.42 to -0.14). Finally, pulses in high-fibre diets (11 trials) lowered FBG (-0.32, 95% CI -0.49 to -0.15) and GP (-0.27, 95% CI -0.45 to -0.09). Inter-study heterogeneity was high and unexplained for most outcomes, with benefits modified or predicted by diabetes status, pulse type, dose, physical form, duration of follow-up, study quality, macronutrient profile of background diets, feeding control and design. Conclusions/interpretation Pooled analyses demonstrated that pulses, alone or in low-GI or high-fibre diets, improve markers of longer term glycaemic control in humans, with the extent of the improvements subject to significant inter-study heterogeneity. There is a need for further large, well-designed trials.
Alveolar echinococcosis (AE) and cystic echinococcosis (CE) are severe helminthic zoonoses. Echinococcus multilocularis (causative agent of AE) is widely distributed in the northern hemisphere where ...it is typically maintained in a wild animal cycle including canids as definitive hosts and rodents as intermediate hosts. The species Echinococcus granulosus, Echinococcus ortleppi, Echinococcus canadensis and Echinococcus intermedius are the causative agents of CE with a worldwide distribution and a highly variable human disease burden in the different endemic areas depending upon human behavioural risk factors, the diversity and ecology of animal host assemblages and the genetic diversity within Echinococcus species which differ in their zoonotic potential and pathogenicity. Both AE and CE are regarded as neglected zoonoses, with a higher overall burden of disease for CE due to its global distribution and high regional prevalence, but a higher pathogenicity and case fatality rate for AE, especially in Asia. Over the past two decades, numerous studies have addressed the epidemiology and distribution of these Echinococcus species worldwide, resulting in better-defined boundaries of the endemic areas. This chapter presents the global distribution of Echinococcus species and human AE and CE in maps and summarizes the global data on host assemblages, transmission, prevalence in animal definitive hosts, incidence in people and molecular epidemiology.
We present our analysis of the long-cadence Kepler data for the well-studied Blazhko star RR Lyr, gathered during the first two quarters of the satellite's observations and covering a total of 127 d. ...Besides being of great importance for our understanding of RR Lyrae stars in general, these RR Lyr data can be regarded as a case study for observations of bright stars with Kepler. Kepler can perform high-precision photometry on targets like RR Lyr, as the saturated flux is conserved to a very high degree. The Kepler data on RR Lyr are revolutionary in several respects. Even with long-cadence sampling (one measurement per 29.4 min), the unprecedented precision (< mmag) of the Kepler photometry allows the study of the star's extreme light-curve variations in detail. The multiplet structures at the main frequency and its harmonics, typical for Blazhko stars, are clearly detected up to the quintuplets. For the first time, photometric data of RR Lyr reveal the presence of half-integer frequencies, linked to a period-doubling effect. This phenomenon may be connected to the still unexplained Blazhko modulation. Moreover, with three observed Blazhko cycles at our disposal, we observe that there is no exact repetition in the light-curve changes from one modulation cycle to the next for RR Lyr. This may be due to additional periodicities in the star, or to transient or quasi-periodic changes.
ABSTRACT
We report on precise Doppler measurements of L231-32 (TOI-270), a nearby M dwarf (d = 22 pc, M⋆ = 0.39 M⊙, R⋆ = 0.38 R⊙), which hosts three transiting planets that were recently discovered ...using data from the Transiting Exoplanet Survey Satellite (TESS). The three planets are 1.2, 2.4, and 2.1 times the size of Earth and have orbital periods of 3.4, 5.7, and 11.4 d. We obtained 29 high-resolution optical spectra with the newly commissioned Echelle Spectrograph for Rocky Exoplanet and Stable Spectroscopic Observations (ESPRESSO) and 58 spectra using the High Accuracy Radial velocity Planet Searcher (HARPS). From these observations, we find the masses of the planets to be 1.58 ± 0.26, 6.15 ± 0.37, and 4.78 ± 0.43 M⊕, respectively. The combination of radius and mass measurements suggests that the innermost planet has a rocky composition similar to that of Earth, while the outer two planets have lower densities. Thus, the inner planet and the outer planets are on opposite sides of the ‘radius valley’ – a region in the radius-period diagram with relatively few members – which has been interpreted as a consequence of atmospheric photoevaporation. We place these findings into the context of other small close-in planets orbiting M dwarf stars, and use support vector machines to determine the location and slope of the M dwarf (Teff < 4000 K) radius valley as a function of orbital period. We compare the location of the M dwarf radius valley to the radius valley observed for FGK stars, and find that its location is a good match to photoevaporation and core-powered mass-loss models. Finally, we show that planets below the M dwarf radius valley have compositions consistent with stripped rocky cores, whereas most planets above have a lower density consistent with the presence of a H-He atmosphere.
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