scholarly journals On the importance of including devolatilized stellar abundances in determining the composition of rocky exoplanets

2021 ◽  
Author(s):  
Fabian Seidler ◽  
Haiyang Wang ◽  
Sascha Quanz
Keyword(s):  
Mass Fraction ◽  
Terrestrial Planets ◽  
Chemical Compositions ◽  
Posterior Distributions ◽  
Stellar Abundances ◽  
Core Mass ◽  
The Core ◽  
Planetary Mass ◽  
Before And After ◽  
Mass Fractions

<p>Since stars and their planets form from the same molecular clouds, stellar chemical composition can be informative, to first order, of planetary bulk chemistry. An important feature of terrestrial planets compared to their host stars is the depletion of volatiles, the most important being oxygen. Previous studies on planet interiors focus on the mass and radius constraints and/or the host stellar refractory elements (e.g. Fe, Si and Mg), neglecting devolatilisation and its impact on the final picture of planet mineralogy and structure. This work assesses to what extent the devolatilised stellar abundances reflect rocky planetary composition.  </p><p>We firstly test how the uncertainties associated with planetary mass and radius would affect the modelling results of core mass fraction – an important interior parameter. To do so, we choose the Sun-like star Kepler-21 (stellar abundance uncertainties <0.05 dex) as a case study and assume it hosts an Earth-mass-and-radius planet in its habitable zone. We then assign different levels of uncertainties to the mass and radius of the hypothetical planet, ranging from 0.1% to 20%. We find that with increasing uncertainty level, the modelling result of core mass fraction constrained by the devolatilised stellar abundances and mass and radius becomes identical with the core mass fraction constrained purely by the devolatilised stellar abundances. This reveals the increased modelling degeneracy with growing uncertainties in mass and radius measurements, but also the strong constraints placed by using the devolatilised stellar abundances.</p><p>We further investigate a sample of 12 confirmed exoplanets, which are all less than 10 Earth masses and 2 Earth radii – i.e. potentially terrestrial planets or super-Earths – and with the measured uncertainties in mass and radius respectively less than 35% and 10%. By comparing the prior and posterior distributions of mass and radius before and after introducing the devolatilised stellar abundances as another prior, we find that the posterior distributions of all samples, but 55 Cnc e and Kepler-107 c, can be sampled within the 2σ ranges of the prior distributions. For the two exceptional cases, it means that the devolatilised stellar abundances and the measured mass and radius are not compatible within the level of 2σ.</p><p>We also find a diverse distribution of the core mass fractions of the sample from 0% (i.e. coreless) up to 40%, which are consistent at the 2σ level with the core mass fractions purely constrained by mass and radius measurements (except Kepler-107 c and 55 Cnc e),  but are significantly constrained by adding the devolatilized stellar abundances. In contrast, the previous study for the similar sample shows nearly constant core mass fractions of ~ 30% based on the unaltered stellar abundances and by assuming 100% Fe sunk into the core (i.e. free of consideration of the oxidation state of the planets). We emphasise that to break the degeneracies of terrestrial-type exoplanet interior modelling, we must use well the currently available observables including planetary mass and radius and host stellar chemical compositions, but they must be viewed through the lens of planet formation  and the resulting devolatilization.</p>

Microstructure and friction-wear performances of laser-cladded nano-CeO2–reinforced NiCoCrAlY coatings at high temperature

2020 ◽  
Vol 234 (14) ◽  
pp. 1695-1706
Author(s):  
Li Jiaxing ◽  
Xu Jie ◽  
Kong Dejun
Keyword(s):  
Mass Fraction ◽  
Energy Dispersive Spectrometer ◽  
Wear Test ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Wear Rates ◽  
Mass Fractions ◽  
The Coefficient Of Friction ◽  
Oxidation Wear ◽  
Main Factor

Nano-CeO2–reinforced NiCoCrAlY coatings were fabricated on Ti6Al4V alloy using laser cladding. The morphologies, chemical compositions, and phases of obtained coatings were analyzed using a scanning electron microscope, energy-dispersive spectrometer, and X-ray diffraction, respectively, and the effects of nano-CeO2 mass fraction on the coefficient of friction and the wear rate of NiCoCrAlY coating at 600 °C were investigated using a ball-on-disk wear test. The results show that the nano-CeO2–reinforced NiCoCrAlY coating is mainly composed of NiTi2, Ti3O, CoO, and β-Ti phases, while the new phases of AlTi3 and (Ni, Co)2Ti4O are formed after the wear test. The average coefficients of friction of NiCoCrAlY coatings with the nano-CeO2 mass fractions of 0%, 2%, 4%, and 6% are 0.699, 0.655, 0.636, and 0.615, respectively, and the corresponding wear rates are 4.04 × 10−7, 3.95 × 10−7, 3.13 × 10−7, and 2.35 × 10−7 mm3 N−1 m−1, respectively, which decrease with the increase of nano-CeO2 mass fraction. The wear mechanism is primary adhesive wear and oxidation wear, accompanied by slight abrasive wear, and the addition of nano-CeO2 is the main factor that is enhancing wear resistance.

scholarly journals Effect of MF-Coated Epoxy Resin Microcapsules on Properties of Waterborne Wood Coating on Basswood

Coatings ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 785 ◽  
Author(s):  
Xiaoxing Yan ◽  
Yijuan Chang
Keyword(s):  
Epoxy Resin ◽  
Mass Fraction ◽  
High Performance ◽  
Impact Resistance ◽  
Color Difference ◽  
Core Material ◽  
Wall Material ◽  
The Core ◽  
Mass Fractions ◽  
The Stability

In this paper, melamine–formaldehyde (MF) was used as the wall material, and epoxy resin was used as the core material to prepare microcapsules. The optical properties, mechanical properties and ageing resistance of waterborne topcoat were investigated by adding different mass fractions of microcapsules into the waterborne topcoat. Through scanning electron microscopy and infrared spectroscopy analysis, the prepared microcapsules of core-wall ratio of 0.50 were more uniform. It was found that when the mass fraction of microcapsules is less than 10.0% and the core–wall ratio is 0.50, the original color difference of the coating can be maintained. With the increase in microcapsule mass fraction, the gloss of the topcoat film gradually decreases. The mass fraction of the microcapsule of 4.0% with the core–wall ratio of 0.50 can maintain the original gloss of 30.0 GU. The topcoat film with the MF-coated epoxy resin microcapsules of the core–wall ratio of 0.50 has high impact resistance, adhesion and hardness. The results showed that the gloss loss and color difference of the coating with the MF-coated epoxy microcapsules were the lowest when the mass fraction of microcapsules was 4.0%, indicating that microcapsules can improve the stability of coating. These results lay a technical foundation for the development and application of high-performance wood coatings.

scholarly journals Effect of Microcapsules of a Waterborne Core Material on the Properties of a Waterborne Primer Coating on a Wooden Surface

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 657 ◽  
Author(s):  
Xiaoxing Yan ◽  
Wenwen Peng
Keyword(s):  
Mass Fraction ◽  
Impact Resistance ◽  
Chromatic Aberration ◽  
Core Material ◽  
Core Shell ◽  
The Core ◽  
Mass Fractions ◽  
Wooden Surface ◽  
The Impact ◽  
Wooden Products

Microcapsules of a waterborne core material were prepared using a waterborne primer. The microcapsules of the waterborne core material were added to the waterborne primer to explore the effects of different core–shell ratios and mass fractions of the microcapsules on the property of the waterborne primer coating on the wooden surface. The results show that as the mass fraction of the microcapsules increased, the chromatic aberration increased by degrees, the glossiness decreased gradually, and the hardness increased by degrees, whilst—except for the coating with 0.50:1 microcapsules—the adhesion decreased gradually. When the mass fraction of the microcapsules increased, the impact resistance increased first and decreased later, or remained unchanged after reaching a certain value. When the mass fraction of the microcapsules increased, the elongation at the break increased first and decreased later. When the core–shell ratio was small and the mass fraction was between 5.0% and 15.0%, the coating had better liquid resistance. When the core–shell ratio was 0.67:1 and the mass fraction was 10.0%, the overall property of the coating on the Basswood was the best. The technology of microencapsulation provides a technical reference for the waterborne primer with self-repair qualities on the surface of wooden products.

scholarly journals Unveiling the planet population at birth

2021 ◽  
Vol 503 (1) ◽  
pp. 1526-1542 ◽  
Author(s):  
James G Rogers ◽  
James E Owen
Keyword(s):  
Mass Distribution ◽  
Mass Fraction ◽  
Additional Mass ◽  
Core Mass ◽  
Water Ice ◽  
The Core ◽  
Core Composition ◽  
Peak Mass ◽  
Core Accretion ◽  
Atmospheric Mass

ABSTRACT The radius distribution of small, close-in exoplanets has recently been shown to be bimodal. The photoevaporation model predicted this bimodality. In the photoevaporation scenario, some planets are completely stripped of their primordial H/He atmospheres, whereas others retain them. Comparisons between the photoevaporation model and observed planetary populations have the power to unveil details of the planet population inaccessible by standard observations, such as the core mass distribution and core composition. In this work, we present a hierarchical inference analysis on the distribution of close-in exoplanets using forward models of photoevaporation evolution. We use this model to constrain the planetary distributions for core composition, core mass, and initial atmospheric mass fraction. We find that the core-mass distribution is peaked, with a peak-mass of ∼4M⊕. The bulk core-composition is consistent with a rock/iron mixture that is ice-poor and ‘Earth-like’; the spread in core-composition is found to be narrow ($\lesssim 16{{\ \rm per\ cent}}$ variation in iron-mass fraction at the 2σ level) and consistent with zero. This result favours core formation in a water/ice poor environment. We find the majority of planets accreted a H/He envelope with a typical mass fraction of $\sim 4{{\ \rm per\ cent}}$; only a small fraction did not accrete large amounts of H/He and were ‘born-rocky’. We find four times as many super-Earths were formed through photoevaporation, as formed without a large H/He atmosphere. Finally, we find core-accretion theory overpredicts the amount of H/He cores would have accreted by a factor of ∼5, pointing to additional mass-loss mechanisms (e.g. ‘boil-off’) or modifications to core-accretion theory.

scholarly journals Size Evolution of Close-in Super-Earths through Giant Impacts and Photoevaporation

2021 ◽  
Vol 923 (1) ◽  
pp. 81
Author(s):  
Yuji Matsumoto ◽  
Eiichiro Kokubo ◽  
Pin-Gao Gu ◽  
Kenji Kurosaki
Keyword(s):  
Radial Profile ◽  
Analytical Models ◽  
Core Mass ◽  
Outer Planets ◽  
The Core ◽  
Size Evolution ◽  
Wide Range ◽  
Mass Fractions ◽  
Giant Impacts ◽  
Impact Phase

Abstract The Kepler transit survey with follow-up spectroscopic observations has discovered numerous super-Earth sized planets and revealed intriguing features of their sizes, orbital periods, and their relations between adjacent planets. For the first time, we investigate the size evolution of planets via both giant impacts and photoevaporation to compare with these observed features. We calculate the size of a protoplanet, which is the sum of its core and envelope sizes, by analytical models. N-body simulations are performed to evolve planet sizes during the giant impact phase with envelope stripping via impact shocks. We consider the initial radial profile of the core mass and the initial envelope mass fractions as parameters. Inner planets can lose their whole envelopes via giant impacts, while outer planets can keep their initial envelopes, because they do not experience giant impacts. Photoevaporation is simulated to evolve planet sizes afterward. Our results suggest that the period-radius distribution of the observed planets would be reproduced if we perform simulations in which the initial radial profile of the core mass follows a wide range of power-law distributions and the initial envelope mass fractions are ∼0.1. Moreover, our model shows that the adjacent planetary pairs have similar sizes and regular spacings, with slight differences from detailed observational results such as the radius gap.

Nilai-Nilai Pendidikan Akhlak dalam Al-Qur’an

2018 ◽  
Vol 10 (2) ◽  
pp. 269-295
Author(s):  
Sri Waluyo
Keyword(s):  
Moral Education ◽  
Primary Source ◽  
Secondary Data ◽  
Primary Data ◽  
The Core ◽  
Primary Data Source ◽  
Before And After ◽  
Data Source

This paper discusses the content of Q.S. al-Baqarah ([2]: 67-73). The data used in the preparation of this paper is the data that is primary and secondary. The primary source is data obtained from the core source. In conducting a study of a verse, it is clear that the primary data source is derived from the Qur'an,precisely on Q.S. al-Baqarah ([2]: 67-73). Secondary data is dataobtained from other sources that are still related to the problemand provide interpretation of the primary source. The method usedin analyzing this paper is the tahlili method. This method describesthe meaning contained by the Qur'an, verse by verse, and letterafter letter according to the order in the Mushaf. The descriptionincludes the various aspects which the interpreted verses contain,such as the meaning of the vocabulary, the connotation of thesentence, the background of the verse down, its relation to otherverses, both before and after. And do not miss the opinion that hasbeen given regarding the interpretation of these verses, whetherdelivered by the Prophet, companions, the tabi'in, as well as othercommentators. This study shows that in Q.S. (2): 67-73) there arevalues of moral education which include: 1) morals in asking, (2)morals to parents, (3) patience of educators, (4) educator honesty,and (5) obedience of learners.

A technique for uranium and plutonium determination using coulometric potentiostatic facility UPK-19 for analysis of mixed-oxide fuel

2020 ◽  
Vol 86 (12) ◽  
pp. 15-22
Author(s):  
N. A. Bulayev ◽  
E. V. Chukhlantseva ◽  
O. V. Starovoytova ◽  
A. A. Tarasenko
Keyword(s):  
Acid Solution ◽  
Mass Fraction ◽  
Background Electrolyte ◽  
Stable State ◽  
Sulfamic Acid ◽  
Oxide Fuel ◽  
Oxidation Current ◽  
Mox Fuel ◽  
Mass Fractions ◽  
Uranium Plutonium

The content of uranium and plutonium is the main characteristic of mixed uranium-plutonium oxide fuel, which is strictly controlled and has a very narrow range of the permissible values. We focused on developing a technique for measuring mass fractions of uranium and plutonium by controlled potential coulometry using a coulometric unit UPK-19 in set with a R-40Kh potentiostat-galvanostat. Under conditions of sealed enclosures, a special design of the support stand which minimized the effect of fluctuations in ambient conditions on the signal stability was developed. Optimal conditions for coulometric determination of plutonium and uranium mass fractions were specified. The sulfuric acid solution with a molar concentration of 0.5 mol/dm3 was used as a medium. Lead ions were introduced into the background electrolyte to decrease the minimum voltage of hydrogen reduction to –190 mV. The addition of aluminum nitride reduced the effect of fluoride ions participating as a catalyst in dissolving MOX fuel samples, and the interfering effect of nitrite ions was eliminated by introducing a sulfamic acid solution into the cell. The total content of uranium and plutonium was determined by evaluation of the amount of electricity consumed at the stage of uranium and plutonium co-oxidation. Plutonium content was measured at the potentials, at which uranium remains in the stable state, which makes it possible to subtract the contribution of plutonium oxidation current from the total oxidation current. The error characteristics of the developed measurement technique were evaluated using the standard sample method and the real MOX fuel pellets. The error limits match the requirements set out in the specifications for MOX fuel. The technique for measuring mass fractions of uranium and plutonium in uranium-plutonium oxide nuclear fuel was certified. The relative measurement error of the mass fraction of plutonium and uranium was ±0.0070 and ±0.0095, respectively. The relative error of the ratio of the plutonium mass fraction to the sum of mass fractions of uranium and plutonium was ±0.0085.

scholarly journals Numerical Investigation of the Effect of Air Leaking into the Working Fluid on the Performance of a Steam Ejector

2021 ◽  
Vol 11 (13) ◽  
pp. 6111
Author(s):  
He Li ◽  
Xiaodong Wang ◽  
Jiuxin Ning ◽  
Pengfei Zhang ◽  
Hailong Huang
Keyword(s):  
Flow Structure ◽  
Mass Fraction ◽  
Internal Flow ◽  
Working Fluid ◽  
Physical Parameters ◽  
Entrainment Ratio ◽  
Air Mass ◽  
Steam Ejector ◽  
Primary Fluid ◽  
Mass Fractions

This paper investigated the effect of air leaking into the working fluid on the performance of a steam ejector. A simulation of the mixing of air into the primary and secondary fluids was performed using CFD. The effects of air with a 0, 0.1, 0.3 and 0.5 mass fraction on the entrainment ratio and internal flow structure of the steam ejector were studied, and the coefficient distortion rates for the entrainment ratios under these air mass fractions were calculated. The results demonstrated that the air modified the physical parameters of the working fluid, which is the main reason for changes in the entrainment ratio and internal flow structure. The calculation of the coefficient distortion rate of the entrainment ratio illustrated that the air in the primary fluid has a more significant impact on the change in the entrainment ratio than that in the secondary fluid under the same air mass fraction. Therefore, the air mass fraction in the working fluid must be minimized to acquire a precise entrainment ratio. Furthermore, this paper provided a method of inspecting air leakage in the experimental steam ejector refrigeration system.

scholarly journals Formation of GW190521 from stellar evolution: the impact of the hydrogen-rich envelope, dredge-up and 12C(α, γ)16O rate on the pair-instability black hole mass gap

2020 ◽  
Author(s):  
Guglielmo Costa ◽  
Alessandro Bressan ◽  
Michela Mapelli ◽  
Paola Marigo ◽  
Giuliano Iorio ◽  
...  
Keyword(s):  
Stellar Evolution ◽  
Reaction Rate ◽  
Primary Component ◽  
Mass Reduction ◽  
Black Hole Mass ◽  
Core Mass ◽  
The Core ◽  
Mass Gap ◽  
M Stars ◽  
The Impact

Abstract Pair-instability (PI) is expected to open a gap in the mass spectrum of black holes (BHs) between ≈40 − 65 M⊙ and ≈120 M⊙. The existence of the mass gap is currently being challenged by the detection of GW190521, with a primary component mass of $85^{+21}_{-14}$ M⊙. Here, we investigate the main uncertainties on the PI mass gap: the 12C(α, γ)16O reaction rate and the H-rich envelope collapse. With the standard 12C(α, γ)16O rate, the lower edge of the mass gap can be 70 M⊙ if we allow for the collapse of the residual H-rich envelope at metallicity Z ≤ 0.0003. Adopting the uncertainties given by the starlib database, for models computed with the 12C(α, γ)16O rate −1 σ, we find that the PI mass gap ranges between ≈80 M⊙ and ≈150 M⊙. Stars with MZAMS > 110 M⊙ may experience a deep dredge-up episode during the core helium-burning phase, that extracts matter from the core enriching the envelope. As a consequence of the He-core mass reduction, a star with MZAMS = 160 M⊙ may avoid the PI and produce a BH of 150 M⊙. In the −2 σ case, the PI mass gap ranges from 92 M⊙ to 110 M⊙. Finally, in models computed with 12C(α, γ)16O −3 σ, the mass gap is completely removed by the dredge-up effect. The onset of this dredge-up is particularly sensitive to the assumed model for convection and mixing. The combined effect of H-rich envelope collapse and low 12C(α, γ)16O rate can lead to the formation of BHs with masses consistent with the primary component of GW190521.

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