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Aims. Our aim in this paper is to refine the orbital and physical parameters of the HATS-2 planetary system and study transit timing variations and atmospheric composition thanks to transit observations that span more than 10 yr and that were collected using different instruments and pass-band filters. We also investigate the orbital alignment of the system by studying the anomalies in the transit light curves induced by starspots on the photosphere of the parent star. Methods. We analysed new transit events from both ground-based telescopes and NASA's TESS mission. Anomalies were detected in most of the light curves and modelled as starspots occulted by the planet during transit events. We fitted the clean and symmetric light curves with the JKTEBOP code and those affected by anomalies with the PRISM+GEMC codes to simultaneously model the photometric parameters of the transits and the position, size, and contrast of each starspot. Results. We found consistency between the values we found for the physical and orbital parameters and those from the discovery paper and ATLAS9 stellar atmospherical models. We identified different sets of consecutive starspot-crossing events that temporally occurred in less than five days. Under the hypothesis that we are dealing with the same starspots, occulted twice by the planet during two consecutive transits, we estimated the rotational period of the parent star and, in turn the projected and the true orbital obliquity of the planet. We find that the system is well aligned. We identified the possible presence of transit timing variations in the system, which can be caused by tidal orbital decay, and we derived a low-resolution transmission spectrum. [ABSTRACT FROM AUTHOR]

Transits in the planetary system WASP-4 were recently found to occur 80 s earlier than expected in observations from the TESS satellite. We present 22 new times of mid-transit that confirm the existence of transit timing variations, and are well fitted by a quadratic ephemeris with period decay d P /d t  = −9.2 ± 1.1 ms yr−1. We rule out instrumental issues, stellar activity, and the Applegate mechanism as possible causes. The light-time effect is also not favoured due to the non-detection of changes in the systemic velocity. Orbital decay and apsidal precession are plausible but unproven. WASP-4 b is only the third hot Jupiter known to show transit timing variations to high confidence. We discuss a variety of observations of this and other planetary systems that would be useful in improving our understanding of WASP-4 in particular and orbital decay in general. [ABSTRACT FROM AUTHOR]

This data paper presents lightcurves of 101 near Earth asteroids (NEAs) observed mostly between 2014 and 2017 as part of the EURONEAR photometric survey using 11 telescopes with diameters between 0.4 and 4.2 m located in Spain, Chile, Slovakia and Romania. Most targets had no published data at the time of observing, but some objects were observed in the same period mainly by B. Warner, allowing us to confirm or improve the existing results. To plan the runs and select the targets, we developed the public Long Planning tool in PHP. For preliminary data reduction and rapid follow-up planning we developed the LiDAS pipeline in Python and IRAF. For final data reduction, flux calibration, night linkage and Fourier fitting, we used mainly MPO Canopus. Periods of 18 targets are presented for the first time, and we could solve or constrain rotation for 16 of them. We secured periods for 45 targets ( $$U\sim 3$$ ), found candidate periods for other 16 targets ( $$U\sim 2$$ ), and we propose tentative periods for other 32 targets ( $$U\sim 1$$ ). We observed 7 known or candidate binary NEAs, fiting 3 of them (2102 Tantalus, 5143 Heracles and 68348). We observed 8 known or candidate tumbling NEAs, deriving primary periods for 3 objects (9400, 242708 and 470510). We evidenced rapid oscillations (few minutes) and could fit fast tentative periods TP2 for 5 large newly suggested tumbling or binary candidates (27346, 112985, 285625, 377732, 408980), probably discovering at least one new binary NEA (2011 WO41). We resolved periods of 4 special objects which include two proposed space mission targets (163249 and 101955 Bennu), one very fast rotator NEA discovered by EURONEAR (2014 NL52) and the 'Halloween asteroid' (2015 TB145). Using Mercator in simultaneous 3 band MAIA imaging, we could evidence for the first time clear variation in the color lightcurves of 10 NEAs. The periods derived from the g- r color lightcurves are found to match individual band period fits for 4 NEAs (27346, 86067, 112985 and 275976). [ABSTRACT FROM AUTHOR]

The non-linear behavior of uniform-size cellular foams made of aluminum is investigated when subjected to compressive loads while comparing numerical results obtained in the Finite Element Method software (FEM) ANSYS workbench and ANSYS Mechanical APDL (ANSYS Parametric Design Language). The numerical model is built on AUTODESK INVENTOR, being imported into ANSYS and solved by the Newton-Raphson iterative method. The most similar conditions were used in ANSYS mechanical and ANSYS workbench, as possible. The obtained numerical results and the differences between the two programs are presented and discussed [ABSTRACT FROM AUTHOR]

We present 13 high-precision and four additional light curves of four bright southernhemisphere transiting planetary systems: WASP-22, WASP-41, WASP-42 and WASP-55. In the cases of WASP-42 and WASP-55, these are the first follow-up observations since their discovery papers. We present refined measurements of the physical properties and orbital ephemerides of all four systems. No indications of transit timing variations were seen. All four planets have radii inflated above those expected from theoretical models of gas-giant planets; WASP-55 b is the most discrepant with a mass of 0.63MJup and a radius of 1.34 RJup. WASP-41 shows brightness anomalies during transit due to the planet occulting spots on the stellar surface. Two anomalies observed 3.1 d apart are very likely due to the same spot. We measure its change in position and determine a rotation period for the host star of 18.6 ± 1.5 d, in good agreement with a published measurement from spot-induced brightness modulation, and a sky-projected orbital obliquity of λ = 6 ± 11°. We conclude with a compilation of obliquity measurements from spot-tracking analyses and a discussion of this technique in the study of the orbital configurations of hot Jupiters. [ABSTRACT FROM AUTHOR]

The intervertebral disc is submitted to complex loading during its normal daily activities which are responsible for variations of the hydrostatic pressure in its structure. Thus, the determination of the magnitude of failure hydrostatic pressure is essential as a potential for the evaluation of the mechanisms that promote the weakening and the disruption of the annular fibers, commonly linked to herniation process on the spine column. However, few studies include the determination of the failure pressure on discs and the results are widely contradictory. Therefore, the objective of the present work is to determine the values of IDP that promotes the disc disruption. To achieve this goal, the tests were performed using a hydraulic cylinder that inflates the intervertebral disc. The results revealed a mean pressure failure of 0.62-0.08MPa for lumbar porcine samples (nD6). From this approach it can be concluded that (1) the potential for disc injury may exist at low pressures for lumbar porcine discs when compared several animal and human ones; (2) the rupture of human cervical and porcine lumbar annular fibers could occur for values of intradiscal pressure that are within the physiological range. [ABSTRACT FROM AUTHOR]

Context. The Kuiper belt is formed of planetesimals which failed to grow to planets and its dynamical structure has been affected by Neptune. The classical Kuiper belt contains objects both from a low-inclination, presumably primordial, distribution and from a high-inclination dynamically excited population. Aims. Based on a sample of classical transNeptunian objects (TNOs) with observations at thermal wavelengths we determine radiometric sizes, geometric albedos and thermal beaming factors for each object as well as study sample properties of dynamically hot and cold classicals. Methods. Observations near the thermal peak of TNOs using infrared space telescopes are combined with optical magnitudes using the radiometric technique with near-Earth asteroid thermal model (NEATM). We have determined three-band flux densities from Herschel/PACS observations at 70.0, 100.0 and 160.0 μm and Spitzer/MIPS at 23.68 and 71.42 μm when available. We use reexamined absolute visual magnitudes from the literature and ground based programs in support of Herschel observations. Results. We have analysed 18 classical TNOs with previously unpublished data and reanalysed previously published targets with updated data reduction to determine their sizes and geometric albedos as well as beaming factors when data quality allows. We have combined these samples with classical TNOs with radiometric results in the literature for the analysis of sample properties of a total of 44 objects. We find a median geometric albedo for cold classical TNOs of 0.14+0.09 -0.07 and for dynamically hot classical TNOs, excluding the Haumea family and dwarf planets, 0.085+0.084 -0.045. We have determined the bulk densities of Borasisi-Pabu (2.1+2.6 -1.2 g cm-3), Varda-Ilmarë (1.25+0.40 -0.43 g cm-3) and 2001 QC298 (1.14+0.34 -0.30 g cm-3) as well as updated previous density estimates of four targets. We have determined the slope parameter of the debiased cumulative size distribution of dynamically hot classical TNOs as q = 2.3 ± 0.1 in the diameter range 100 < D < 500 km. For dynamically cold classical TNOs we determine q = 5.1 ± 1.1 in the diameter range 160 < D < 280 km as the cold classical TNOs have a smaller maximum size. [ABSTRACT FROM AUTHOR]

Context. Centaurs are the transitional population between trans-Neptunian objects (TNOs) and Jupiter-family comets. Their physical properties provide an insight into TNO properties, but only under restricted conditions since Centaurs are closer to the Sun and Earth. For this reason it is possible to access the smaller ones, which is more difficult to do with the TNO population. Aims. The goal of this work is to characterize a set of 16 Centaurs in terms of their size, albedo, and thermal properties. We study the correlations, for a more extended sample obtained from the literature, of diameter, albedo, orbital parameters, and spectral slopes. Methods. We performed three-band photometric observations using Herschel-PACS and used a consistent method for the data reduction and aperture photometry of this sample to obtain monochromatic flux densities at 70, 100, and 160 μm. Additionally, we used Spitzer-MIPS flux densities at 24 and 70 μm when available. We also included in our Centaur sample scattered disk objects, a dynamical family of TNOs, using results previously published by our team, and some Centaurs observed only with the Spitzer-MIPS instrument. Results. We have determined new radiometric sizes and albedos of 16 Centaurs. The first conclusion is that the albedos of Centaur objects are not correlated with their orbital parameters. Similarly, there is no correlation between diameter and orbital parameters. Most of the objects in our sample are dark (pv < 7%) and most of them are small (D < 120 km). However, there is no correlation between albedo and diameter, in particular for the group of small objects as albedo values are homogeneously distributed between 4 to 16%. The correlation with the color of the objects showed that red objects are all small (mean diameter 65 km), while the gray ones span a wide range of sizes (mean diameter 120 km). Moreover, the gray objects tend to be darker, with a mean albedo of 5.6%, compared with a mean of 8.5% (ranging from 5 to 15%) for the red objects. [ABSTRACT FROM AUTHOR]

This study presents an alternative approach for the absorption of impact energy that uses the internal pressurization of structures in the framework of a crash-adaptive response. Numerical simulations were conducted on axial impact of thin-walled tubular structures with circular cross section that serve as an approximation to a front crash box of a motor vehicle. The main objective of this work consists in studying the effect of internal pressurization of tubular structures in a crashworthiness application, as well as the possibility to obtain a reduction in wall thickness thus improving weight efficiency. A numerical study is presented for an internal pressure of 20 bar and tubular structures of circular section and 1.14 mm thickness. Numerical simulations were performed recurring to LS-DYNA explicit dynamics software while considering for the material a stainless steel alloy that is a material with interest for crashworthiness applications and manufacturing requisites due to its balance between strength, ductility and energy absorption. The results obtained allow concluding that recurring to internal pressurization it is feasible to reduce the wall thickness and have an impact resistance identical to the original while improving overall efficiency. [ABSTRACT FROM AUTHOR]

Aims. The goal of this work is to characterize the ensemble thermal properties of the Centaurs / trans-Neptunian population. Methods. Thermal flux measurements obtained with Herschel/PACS and Spitzer/MIPS provide size, albedo, and beaming factors for 85 objects (13 of which are presented here for the first time) by means of standard radiometric techniques. The measured beaming factors are influenced by the combination of surface roughness and thermal inertia effects. They are interpreted within a thermophysical model to constrain, in a statistical sense, the thermal inertia in the population and to study its dependence on several parameters. We use in particular a Monte-Carlo modeling approach to the data whereby synthetic datasets of beaming factors are created using random distributions of spin orientation and surface roughness. Results. Beaming factors η range fromvalues <1 to ~2.5, but high η values (>2) are lacking at low heliocentric distances (rh < 30 AU). Beaming factors lower than 1 occur frequently (39% of the objects), indicating that surface roughness effects are important. We determine a mean thermal inertia for Centaurs/ TNO of Г = (2.5 ± 0.5) J m-2 s-1/2 K-1, with evidence of a trend toward decreasing Г with increasing heliocentric (by a factor ~2.5 from 8-25 AU to 41-53 AU). These thermal inertias are 2-3 orders of magnitude lower than expected for compact ices, and generally lower than on Saturn's satellites or in the Pluto/Charon system. Most high-albedo objects are found to have unusually low thermal inertias. Our results suggest highly porous surfaces, in which the heat transfer is affected by radiative conductivity within pores and increases with depth in the subsurface. [ABSTRACT FROM AUTHOR]

Ever since the very first photometric studies of Centaurs and Kuiper belt objects (KBOs) their visible color distribution has been controversial. This controversy has triggered to a prolific debate on the origin of the surface colors of these distant icy objects of the solar system. Two scenarios have been proposed to interpret and explain the large variability of colors, hence surface composition. Are the colors mainly primordial and directly related to the formation region, or are they the result of surface evolution processes? To date, no mechanism has been found that successfully explains why Centaurs, which are escapees from the Kuiper belt, exhibit two distinct color groups, whereas KBOs do not. We readdress this issue using a carefully compiled set of B − R colors and HR(α) magnitudes (as proxy for size) for 253 objects, including data for 10 new small objects. We find that the bimodal color distribution of Centaurs is a size-related phenomenon, common to both Centaurs and small KBOs, i.e. independent of dynamical classification. Furthermore, we find that large KBOs also have a bimodal distribution of surface colors, albeit distinct from the small objects and strongly dependent on the “Haumea collisional family” objects. When plotted in B−R, HR(α) space, the colors of Centaurs and KBOs display a peculiar N shape. [ABSTRACT FROM AUTHOR]

Context. Trans-Neptunian objects (TNO) represent the leftovers of the formation of the solar system. Their physical properties provide constraints to the models of formation and evolution of the various dynamical classes of objects in the outer solar system. Aims. Based on a sample of 19 classical TNOs we determine radiometric sizes, geometric albedos and beaming parameters. Our sample is composed of both dynamically hot and cold classicals. We study the correlations of diameter and albedo of these two subsamples with each other and with orbital parameters, spectral slopes and colors. Methods. We have done three-band photometric observations with Herschel/PACS and we use a consistent method for data reduction and aperture photometry of this sample to obtain monochromatic flux densities at 70.0, 100.0 and 160.0 μm. Additionally, we use Spitzer/MIPS flux densities at 23.68 and 71.42 μm when available, and we present new Spitzer flux densities of eight targets. We derive diameters and albedos with the near-Earth asteroid thermal model (NEATM). As auxiliary data we use reexamined absolute visual magnitudes from the literature and data bases, part of which have been obtained by ground based programs in support of our Herschel key program. Results. We have determined for the first time radiometric sizes and albedos of eight classical TNOs, and refined previous size and albedo estimates or limits of 11 other classicals. The new size estimates of 2002 MS4 and 120347 Salacia indicate that they are among the 10 largest TNOs known. Our new results confirm the recent findings that there are very diverse albedos among the classical TNOs and that cold classicals possess a high average albedo (0.17 ± 0.04). Diameters of classical TNOs strongly correlate with orbital inclination in our sample. We also determine the bulk densities of six binary TNOs. [ABSTRACT FROM AUTHOR]

Context. The Herschel open time key programme TNOs are Cool: A survey of the trans-Neptunian region aims to derive physical and thermal properties for a set of ∼140 Centaurs and trans-Neptunian objects (TNOs), including resonant, classical, detached and scattered disk objects. One goal of the project is to determine albedo and size distributions for specific classes and the overall population of TNOs. Aims. We present Herschel-PACS photometry of 18 Plutinos and determine sizes and albedos for these objects using thermal modeling. We analyze our results for correlations, draw conclusions on the Plutino size distribution, and compare to earlier results. Methods. Flux densities are derived from PACS mini scan-maps using specialized data reduction and photometry methods. In order to improve the quality of our results, we combine our PACS data with existing Spitzer MIPS data where possible, and refine existing absolute magnitudes for the targets. The physical characterization of our sample is done using a thermal model. Uncertainties of the physical parameters are derived using customized Monte Carlo methods. The correlation analysis is performed using a bootstrap Spearman rank analysis. Results. We find the sizes of our Plutinos to range from 150 to 730 km and geometric albedos to vary between 0.04 and 0.28. The average albedo of the sample is 0.08 ± 0.03, which is comparable to the mean albedo of Centaurs, Jupiter family comets and other TNOs. We were able to calibrate the Plutino size scale for the first time and find the cumulative Plutino size distribution to be best fit using a cumulative power law with q = 2 at sizes ranging from 120-400 km and q = 3 at larger sizes. We revise the bulk density of 1999 TC36 and find ϱ = 0.64+0.15 -0.11 g cm-3. On the basis of a modified Spearman rank analysis technique our Plutino sample appears to be biased with respect to object size but unbiased with respect to albedo. Furthermore, we find biases based on geometrical aspects and color in our sample. There is qualitative evidence that icy Plutinos have higher albedos than the average of the sample. [ABSTRACT FROM AUTHOR]

Context. Physical characterization of trans-Neptunian objects, a primitive population of the outer solar system, may provide constraints on their formation and evolution. Aims. The goal of this work is to characterize a set of 15 scattered disk (SDOs) and detached objects, in terms of their size, albedo, and thermal properties. Methods. Thermal flux measurements obtained with the Herschel-PACS instrument at 70, 100 and 160 μm, and whenever applicable, with Spitzer-MIPS at 24 and 70 μm, are modeled with radiometric techniques, in order to derive the objects' individual size, albedo and when possible beaming factor. Error bars are obtained from a Monte-Carlo approach. We look for correlations between these and other physical and orbital parameters. Results. Diameters obtained for our sample range from 100 to 2400 km, and the geometric albedos (in V band) vary from 3.8% to 84.5%. The unweighted mean V geometric albedo for the whole sample is 11.2% (excluding Eris); 6.9% for the SDOs, and 17.0% for the detached objects (excluding Eris). We obtain new bulk densities for three binary systems: Ceto/Phorcys, Typhon/Echidna and Eris/Dysnomia. Apart from correlations clearly due to observational bias, we find significant correlations between albedo and diameter (more reflective objects being bigger), and between albedo, diameter and perihelion distance (brighter and bigger objects having larger perihelia). We discuss possible explanations for these correlations. [ABSTRACT FROM AUTHOR]