Hot Atmosphere Research Articles

The obliquity and atmosphere of the hot Jupiter WASP-122b (KELT-14b) with ESPRESSO: An aligned orbit and no sign of atomic or molecular absorption

Thanks to their short orbital periods and hot extended atmospheres, hot Jupiters are ideal candidates for atmosphere studies with high-resolution spectroscopy. New stable spectrographs help improve our understanding of the evolution and composition of those types of planets. By analyzing two nights of observations using the ESPRESSO high-resolution spectrograph, we studied the architecture and atmosphere of hot Jupiter WASP-122b (KELT-14b). By analyzing the Rossiter-McLaughlin (RM) effect, we measured the spin-orbit angle of the system to be $ $ deg. This result is in line with literature obliquity measurements of planetary systems around stars with effective temperatures cooler than 6500 K. Using the transmission spectroscopy, we studied the atmosphere of the planet. Applying both the single-line analysis and the cross-correlation method, we looked for Ca i Cr i FeH Fe i Fe ii H$_2$O Li i Mg i Na i Ti i TiO V i VO, and Y i . Our results show no evidence of any of these species in WASP-122b's atmosphere. The lack of significant detections can be explained by either the RM effect covering the regions where the atmospheric signal is expected and masking it, along with the low signal-to-noise ratio (S/N) of the observations or the absence of the relevant species in its atmosphere.

Cross-media Integration of Film and Television and Cultural Tourism in the Context of Internet Celebrity Cities

In 2023, with the hit of the TV series "Long Moon Embers", Bengbu will become popular on the whole network, which will make film and television programs and cultural tourism a cross-media integration for a while. Despite the hot atmosphere of the tourism market, the quality of cultural and tourism products is uneven, and it is difficult to live up to the truth under the banner of culture. This not only affects the consumer experience, but also detrimental to the long-term development of the industry. The TV series is detonated, and Bengbu's own profound historical context and urban heritage are the blessings of cultural tourism development. In the face of the city's "out of the circle", Bengbu City should take advantage of the situation to pursue, dig deep into its own resource endowment, and deeply cultivate cultural resources to build a cultural and tourism city; It is necessary to take the opportunity to transform, improve the business environment and industrial ecology, and stimulate the vitality of the city to achieve sustainable development. Do a good job in service with heart and affection, and continue to stimulate new momentum for the development of the cultural tourism market.

Application of hydrostatic local thermodynamic equilibrium atmosphere models to interpretations of supersoft X-ray source spectra

Supersoft X-ray sources (SSSs) are accreting white dwarfs (WDs) with stable or recurrent thermonuclear burning on their surfaces. High-resolution X-ray spectra of such objects are rather complex, often consist of several components, and are difficult to interpret accurately. The main emission source is the hot surface of the WD and the emergent radiation can potentially be described by hot WD model atmospheres. We present a new set of such model atmosphere spectra computed in the effective temperature range from 100 kK to 1000 kK, for eight values of surface gravity and three different chemical compositions. These compositions correspond to the solar one as well as to the Large and Small Magellanic Clouds, with decreased heavy element abundances, at one-half and one-tenth of the solar value. The presented model grid covers a broad range of physical parameters and, thus, it can be applied to a wide range of objects. It is also publicly available in XSPEC format. As an illustration, we applied it here for the interpretation of Chandra and XMM grating spectra of two classical SSSs, namely, CAL 83 (RX J0543.5–6823) and RX J0513.9–6951. The obtained effective temperatures and surface gravities of Teff ≈ 560 kK, log g ≈ 8.6–8.7, and Teff ≈ 630 kK, log g ≈ 8.5–8.6, respectively, are in a good agreement with previous estimations for both sources. The derived WD mass estimations are within 1.1–1.4 M⊙ for CAL 83 and 1.15–1.4 M⊙ for RX J0513.9–6951. The mass of the WD in CAL 83 is consistent with the mass predicted from the respective model of recurrent thermonuclear burning.

The ESO SupJup Survey II. The 12C/13C isotope ratios of three young brown dwarfs with CRIRES+

Young brown dwarfs exhibit atmospheric characteristics similar to those of super-Jupiters, providing a unique opportunity to study planetary atmospheres. Atmospheric retrievals of high-resolution spectra reveal detailed properties of these objects, with elemental and isotopic ratios offering insights into their formation history. The ESO SupJup Survey, utilising CRIRES$^+$ on the Very Large Telescope, aims to assess the role of as a formation tracer. We present observations of three young brown dwarfs: 2MASS J12003792-7845082, TWA 28, and 2MASS J08561384-1342242. Our goal is to constrain their chemical compositions, thermal profiles, surface gravities, spin rotations, and Cratio. We conducted atmospheric retrievals of CRIRES$^+$ K-band spectra, coupling the radiative transfer code petitRADTRANS with the Bayesian inference algorithm MultiNest The retrievals provide a detailed characterisation of the atmospheres of the three objects. We report the volume mixing ratios of the main molecular and atomic species: HF, Na, Ca, and Ti, including the novel detection of hydrogen fluoride (HF) in the atmosphere of a brown dwarf. We determine values of $ and $79^ $ in the atmospheres of TWA 28 and J0856, respectively, with strong significance ($>3 We also report tentative evidence ($ of in J1200, at $. Additionally, we detect at moderate significance in J0856 (3.3sigma ) and TWA 28 (2.1sigma ). The retrieved thermal profiles are consistent with hot atmospheres ($2300-2600$ K) with low surface gravities and slow spins, as expected for young objects. The measured carbon isotope ratios are consistent among the three objects and show no significant deviation from that of the local interstellar medium, suggesting a fragmentation-based formation mechanism similar to star formation. The tentative detection of in two objects of our sample highlights the potential of high-resolution spectroscopy to probe additional isotope ratios, such as O in the atmospheres of brown dwarfs and super-Jupiters.

The 2024 release of the ExoMol database: Molecular line lists for exoplanet and other hot atmospheres

The ExoMol database (www.exomol.com) provides molecular data for spectroscopic studies of hot atmospheres. These data are widely used to model atmospheres of exoplanets, cool stars and other astronomical objects, as well as a variety of terrestrial applications. The 2024 data release reports the current status of the database which contains recommended line lists for 91 molecules and 224 isotopologues giving a total of almost 1012 individual transitions. New features of the database include extensive “MARVELization” of line lists to allow them to be used for high resolutions studies, extension of several line lists to ultraviolet wavelengths, provision of photodissociation cross-sections and extended provision of broadening parameters. Some of the in-house data specifications have been rewritten in JSON and moved for conformity with other international standards. Data products, including specific heats, a database of lifetimes for plasma studies, and the ExoMolHR web app which allows exclusively high resolution data to be extracted, are discussed.

Longitudinal filtering, sponge layers, and equatorial jet formation in a general circulation model of gaseous exoplanets

ABSTRACT General circulation models are a useful tool in understanding the three dimensional structure of hot Jupiter and sub-Neptune atmospheres; however, understanding the validity of the results from these simulations requires an understanding of the artificial dissipation required for numerical stability. In this paper, we investigate the impact of the longitudinal filter and vertical ‘sponge’ used in the Met Office’s unified model when simulating gaseous exoplanets. We demonstrate that excessive dissipation can result in counter-rotating jets and a catastrophic failure to conserve angular momentum. Once the dissipation is reduced to a level where a super-rotating jet forms, however, the jet and thermal structure are relatively insensitive to the dissipation, except in the nightside gyres where temperatures can vary by $\sim 100\, \mathrm{K}$. We do find, however, that flattening the latitudinal profile of the longitudinal filtering alters the results more than a reduction in the strength of the filtering itself. We also show that even in situations where the temperatures are relatively insensitive to the dissipation, the vertical velocities can still vary with the dissipation, potentially impacting physical processes that depend on the local vertical transport.

Ray-traced spectra of a hot neutron star for various metallicities

General relativity strongly affects the observed spectra of compact objects. New models of hot nonrotating neutron star (NS) atmospheres are presented for various chemical compositions. We demonstrate the influence of strong gravity on the value of the hardening factor measured by a distant observer. We prepare new xspec fitting packages based on our extended numerical models for hot NS atmospheres in order to use them for a spectral analysis in the X-ray domain. For the Schwarzschild metric, ray-tracing calculations were performed to determine the observational appearance of the continuum emission of an NS. The grid of intensity spectra emerging from the NS surface was computed with the code which solves the model atmosphere equations with an accurate treatment of the Compton scattering of photons on free electrons in fully relativistic thermal motion. For the single value of the surface gravity, $ =14.34$ (cgs), the emerging specific intensity spectra were then ray-traced from the surface to the distant observer with the code across the spacetime of a nonrotating NS obtained using the lo library. The color-correction factors were determined for a large grid of models of different chemical compositions for surface gravities from the critical gravity $ g_ crit $ up to $15.00$ (cgs), and for effective temperatures in the range of $10^ eff $ K. Comptonized spectra seen at the source rest frame display hardening factors in the range from 1.4 up to 2.0 in the case of a highly luminous metal-rich atmosphere. The ratio of the color temperature $T_ c $ to the effective temperature $T_ eff $ for ray-traced spectra is in the range $0.9-1.4$. In the strong gravity regime, the structure of a hot atmosphere strongly depends on the surface gravity, luminosity, and atmospheric metal abundance of the NS. The theoretical hardening factors of the ray-traced spectra are systematically lower then the hardening factors of spectra at the source by about 30<!PCT!> on average.

Discovery of the Goat Horn complex: a ~1000 deg2 diffuse X-ray source connected to radio loop XII

A dozen patches of polarized radio emission spanning tens of degrees in the form of coherent and stationary arcs and loops are observed at radio frequencies across the sky. Their origin is usually associated with nearby shocks, possibly arising from nearby supernova explosions. The origin of radio loop XII remains unknown. We report an anticorrelation of the radio-polarized emission of loop XII with a large patch of soft X-ray emission found with SRG/ in excess of the background surface brightness in the same region. This seemingly coherent patch of soft X-ray emission, which we call the extends over a remarkable area of $ 1000$ deg$^2$ and includes an arc-shaped enhancement that might trace a cold front. An anticorrelation of the X-ray intensity with the temperature of the plasma that causes the X-ray emission is also observed. The X-ray bright arc seems to anticipate radio loop XII by some degrees on the sky. This behavior can be recast in terms of a correlation between X-ray surface brightness and radio depolarization. We explore and discuss different possible scenarios for the source of the diffuse emission in the Goat Horn complex: a large supernova remnant, an outflow from active star-forming regions in nearby Galactic spiral arms, and a hot atmosphere around the Large Magellanic Cloud. In order to probe these scenarios further, a more detailed characterization of the velocity of the hot gas is required.

Galaxy Groups as the Ultimate Probe of AGN Feedback

The co-evolution between supermassive black holes and their environment is most directly traced by the hot atmospheres of dark matter halos. The cooling of the hot atmosphere supplies the central regions with fresh gas, igniting active galactic nuclei (AGN) with long duty cycles. The outflows from the central engine tightly couple with the surrounding gaseous medium and provide the dominant heating source, preventing runaway cooling. Every major modern hydrodynamical simulation suite now includes a prescription for AGN feedback to reproduce the realistic populations of galaxies. However, the mechanisms governing the feeding/feedback cycle between the central black holes and their surrounding galaxies and halos are still poorly understood. Galaxy groups are uniquely suited to constrain the mechanisms governing the cooling–heating balance, as the energy supplied by the central AGN can exceed the gravitational binding energy of halo gas particles. Here, we provide a brief overview of our knowledge of the impact of AGN on the hot atmospheres of galaxy groups, with a specific focus on the thermodynamic profiles of the groups. We then present our on-going efforts to improve on the implementation of AGN feedback in galaxy evolution models by providing precise measurements of the properties of galaxy groups. We introduce the XMM-Newton Group AGN Project (X-GAP), a large program on XMM-Newton targeting a sample of 49 galaxy groups out to R500c.

Analysis of Public Satisfaction in Tlocor Marine Tourism

The facilities and infrastructure of a tourist attraction are an important factor in assessing public satisfaction in the tourism sector. This is useful in providing comfort for tourists to visit it. The problem with Tlocor Marine Tourism is the lack of internet connection and the hot tourist atmosphere. Apart from that, to board the ship, visitors must wait until there are a minimum of 10 people before they can depart for their destination. This research aims to analyze the level of satisfaction of visitors and the public at Tlocor Marine Tourism. The method used is a quantitative descriptive approach with a research sample of 60 people consisting of 30 visitors and 30 people from the community around Tlocor Marine Tourism. The data analysis technique used is the crosstab model, which compares visitor satisfaction with the satisfaction of the community around Tlocor Marine Tourism. The research results show that the level of visitor satisfaction at Tlocor Marine Tourism is 46 percent in the high category. Meanwhile, the level of satisfaction of the surrounding community at Tlocor Marine Tourism is 50 percent in the very high category.

Land–atmosphere coupling exacerbates the moisture-associated heterogeneous impacts of compound extreme events on maize yield in China

Compound climate events are major threats to crop production under climate change. However, the heterogeneity in the impact of compound events on crop yield and its drivers remain poorly understood. Herein, we used empirical approach to evaluate the impact of compound hot–dry (HD) and cold–wet (CW) events on maize yield in China at the county level from 1990 to 2016, with a special focus on the spatial heterogeneity. Our findings indicate comparable impact of extremely compound CW events (−12.8 ± 3.6%) on maize yield loss to extremely compound HD events (−11.3 ± 2.1%). The spatial pattern of compound HD and CW events impacts on maize yield was dominantly associated with moisture regime, followed by management practices and soil properties. Specifically, drier counties and counties with less fraction of clay soil and organic carbon tend to experience greater yield loss due to compound HD events, and wet condition, excessive fertilizer, clay soil and rich organic carbon aggravate the maize yield loss due to compound CW events. Moreover, the land–atmosphere coupling exacerbated the heterogeneous yield impact through divergent heat transfer. In drier regions, the greater proportion of sensible heat creates a positive feedback between drier land and hotter atmosphere. In contrast, the greater proportion of latent heat in wetter regions results in a positive feedback between wetter land and colder atmosphere. Our results highlighted a critical element to explore in further studies focused on the land–atmosphere coupling in agricultural risk under climate change.

Design and Construction of a Rapid Milk Chiller Using Cold Energy Storage System in the Context of Bangladesh

Milk is a highly sensitive product that must be collected and cooled within a few hours to reduce losses due to chemical spoilage and to preserve quality. As milk production is often remote from markets and processing facilities, milk chillers using thermal energy storage (TES) units provide the means for preserving quality through chilling during a power cut and hygienic storage before onward transportation to processing facilities and operation of the chiller at maximum thermal efficiency. This study gives an overview of thermal energy storage (TES) base rapid milk chiller. A review of TES for cold storage applications utilizing solid-liquid phase change materials has been done. Various perspectives were focused on the different stages of the work: phase change materials (PCMs), exemplification, improvement in exchange of heat, and the impact of the whole process on the quality of the milk Materials used as potential PCMs by specialists at low temperatures (less than 4 °C) are condensed and a portion of their thermo-physical properties are accounted for. The concept of planning and measuring procedures based on the determined load profile for structure day is introduced. In this design of a milk chilling unit using thermal energy storage, two cycles have been combined to get the desired cooling temperature. One is the vapor compression cycle, which can also be called the ice storage cycle. Another one is the milk chilling cycle. The main purpose of the milk chilling cycle is to keep the milk temperature between 2°C to 4°C. The comparison of using cold water with ethylene glycol (PCM) as a storage source of refrigeration for the milk cooling process based on the compressor capacity, ice storage box volume, and power consumed at the variable of cooling load is presented. Also, the effect of using cold storage to reduce the refrigeration capacity and energy saving is presented. The time duration of the milk chiller’s capacity to keep a specific amount (20 liters) of milk cool has been calculated to determine the variance and efficiency of the system compared to other milk chilling processes. Some suggestions concerning the planning of milk chiller hardware are given. Unique consideration was paid to the examination of explicit highlights of heat transfer phenomena in ice storage boxes including the appraisal of the length and the rate of ice arrangement and dissolution. The approach of estimating parts of the ice storage capacity framework incorporated into the milk chilling framework arranged in hot, wet, and dry atmospheres is exhibited. In light of the hourly cooling burden figuring that was completed utilizing Carrier’s Hourly Analysis Program, estimating the ice thermal capacity framework for various working procedures including full, chiller priority, and ice priority storage tasks for the design are displayed. At last, an examination of some operational qualities of the framework is broken down.

Spectroscopic diagnostics of lead stratification in hot subdwarf atmospheres

ABSTRACT Heavy metal subdwarfs are a class of hot subdwarfs with very high abundances of heavy elements, typically around 10 000 times solar. They include stars, which are strongly enhanced in either lead or zirconium, as well as other elements. Vertical stratification of the enhanced elements, where the element is concentrated in a thin layer of the atmosphere, has been proposed as a mechanism to explain the apparent high abundances. This paper explores the effects of the vertical stratification of lead on the theoretical spectra of hot subdwarfs. The concentration of lead in different regions of the model atmosphere is found to affect individual lines in a broadly wavelength-dependent manner, with the potential for lines to display modified profiles depending on the location of lead enhancement in the atmosphere. This wavelength dependence highlights the importance of observations in both the optical and the UV for determining whether stratification is present in real stars.

Hydrogenated atmospheres of lava planets: Atmospheric structure and emission spectra

Ultra-hot rocky super-Earths are thought to be sufficiently irradiated by their host star to melt their surface and allow for long-lasting magma oceans as a result. A number of processes have been proposed to explain how such planets may have retained the primordial hydrogen captured during their formation, while moving inward in the planetary system. The new generation of space telescopes such as the James Webb Space Telescope may provide observations that are precise enough to characterize the atmospheres and perhaps the interiors of such exoplanets. We used a vaporization model that calculates the gas-liquid equilibrium between the atmosphere (including hydrogen) and the magma ocean to compute the elemental composition of a variety of atmospheres with different quantities of hydrogen. We then used the elemental composition in a steady-state atmospheric model (ATMO) to compute the atmospheric structure and generate synthetic emission spectra. With this method, we were able to confirm previous results showing that silicate atmospheres exhibit a thermal inversion, with a notable emission peak of SiO at 9 μm. We compared our method to the literature on the inclusion of hydrogen in the atmosphere to show that hydrogen reduces the thermal inversion because of the formation of H2O, which has a strong greenhouse potential. However, planets that are significantly irradiated by their host star are sufficiently hot to dissociate H2O, thus also allowing them to maintain a thermal inversion. The observational implications are twofold: (1) H2O is more likely to be detected in colder atmospheres and (2) detecting a thermal inversion in hotter atmospheres does not a priori exclude the presence of H (in its atomic form). Due to the impact of H on the overall chemistry and atmospheric structure (and, thus, observations), we emphasize the importance of including volatiles in the calculation of the gas-liquid equilibrium. Finally, we provide a criterion to determine potential targets for observation in light of these findings.

New theoretical study of potassium perturbed by He and a comparison to laboratory spectra

The visible and near-infrared spectra of late L- and T-type dwarf stars are dominated in large part by the resonance lines of neutral Na and K. It is the collision broadening of these atomic lines by H2 and He in the stellar atmosphere that determines the continuum from below 0.5 µm to above 0.9 µm in the spectrum. Their line profiles can be detected as far as 3000 cm−1 from the line center in T dwarfs and consequently an accurate and detailed determination of the complete profile, including the extreme far wing, is required to model the contribution of these strong alkali resonance lines to brown dwarf spectra. We report on our new calculations of unified line profiles of K perturbed by He using ab initio potential data for the conditions prevailing in cool substellar brown dwarfs and hot dense planetary atmospheres with temperatures from Teff = 500 to 3000 K. For such objects with atmospheres of H2 and He, conventional laboratory absorption spectroscopy can be used to examine the line wings and test the line shape theories and molecular potentials. We find that an analytical Lorentzian profile is useful for a few cm−1 from the line center, but not in the line wings, where the radiative transfer is a consequence of the K–He radiative collisions that are sensitive to the interaction potentials. Tables of the K–He absorption coefficients of the resonance lines allow accurate model atmospheres and synthetic spectra. For this purpose, we present new opacities from comprehensive line shape theory incorporating accurate ab initio potentials. Use of these new tables for the modeling of emergent spectra will be an improvement over previous line shape approximations based on incomplete or inaccurate potentials. We also present Lorentzian impact parameters obtained in the semi-classical and quantum theory for the K 4s − 4p resonance line centered at 0.77 µm specifically for the line core regime.

Magnetohydrodynamic Poynting Flux Vortices in the Solar Atmosphere and Their Role in Concentrating Energy

The nature of energy generation, transport, and effective dissipation responsible for maintaining a hot solar upper atmosphere is still elusive. The Poynting flux is a vital parameter for describing the direction and magnitude of the energy flow, which is mainly used in solar physics for estimating the upward energy generated by photospheric plasma motion. This study presents a pioneering 3D mapping of the magnetic energy transport within a numerically simulated solar atmosphere. By calculating the Finite Time Lyapunov Exponent of the energy velocity, defined as the ratio of the Poynting flux to the magnetic energy density, we precisely identify the sources and destinations of the magnetic energy flow throughout the solar atmosphere. This energy mapping reveals the presence of transport barriers in the lower atmosphere, restricting the amount of magnetic energy from the photosphere reaching the chromosphere and corona. Interacting kinematic and magnetic vortices create energy channels, breaking through these barriers and allowing three times more energy input from photospheric motions to reach the upper atmosphere than before the vortices formed. The vortex system also substantially alters the energy mapping, acting as a source and deposition of energy, leading to localized energy concentration. Furthermore, our results show that the energy is transported following a vortical motion: the Poynting flux vortex. In regions where these vortices coexist, they favor conditions for energy dissipation through ohmic and viscous heating, since they naturally create large gradients in the magnetic and velocity fields over small spatial scales. Hence, the vortex system promotes local plasma heating, leading to temperatures around a million Kelvins.

CULTURE SHOCK SANTRI ASAL KANGEAN DI PONDOK PESANTREN SALAFIYAH SYAFI’IYAH SUKOREJO SITUBONDO


 This article discusses the culture shock of students from Kangean at the Salafiyah Syafi'iyah
 Islamic Boarding School in Sukorejo, Situbondo. Culture shock is a situation where a person is
 not familiar with the social habits of a new culture, so that an
 individual cannot display behavior
 that is in accordance with the rules in the new environment. The students from Kangean, who are
 from the island of Madura, are students who tend to be tough in character. But he will love people
 who don't hurt him. It is
 important to know about the community's background in terms of area
 and geographical conditions because people from the beach have a different character from people
 from the mountains. From the beach every day they fight the waves, feel the hot atmosphere
 with
 the hot sun so that psychologically they are associated with a reactive attitude towards something.
 When entering a new environment, namely an Islamic boarding school in Java, it was interesting
 to see how this Satri from Kangean communicated with peo
 ple of a different culture, and reached
 the level of culture shock.
 This research uses a descriptive qualitative research method. A method
 for examining the status of a group of people, an object, a condition, a system of thought, or a class
 of events in t
 he present. The aim of this descriptive research is to create a systematic, factual and
 accurate description, picture or painting of the facts, characteristics and relationships between the
 phenomena being investigated. The results of this research are tha
 t in the adaptation process,
 Kangean students go through phases of cultural adaptation, such as the honeymoon phase where
 students from Kangean experience a move so that they will feel happy because they are in a new
 atmosphere, the Disintegration phase of
 culture shock where students from Kangean will
 experience a the feeling of discomfort caused by differences, then the adjustment phase
 (Reintegration) where the students from Kangean begin to open themselves up to cultural
 differences, then the Autonomy p
 hase (familiarity with the situation) phase where a person
 becomes increasingly able to adapt because he has passed the previous phases like his anxiety and
 restlessness can be accepted and he accepts all the differences that exist. And the last one is the
 Independence phase, a phase where they enjoy the existing differences and a person is more
 confident when faced with the rhythm of a new environment and existing challenges
 
 
 

A cooling flow around the low-redshift quasar H1821+643

ABSTRACT H1821+643 is the nearest quasar hosted by a galaxy cluster. The energy output by the quasar, in the form of intense radiation and radio jets, is captured by the surrounding hot atmosphere. Here, we present a new deep Chandra observation of H1821+643 and extract the hot gas properties into the region where Compton cooling by the quasar radiation is expected to dominate. Using detailed simulations to subtract the quasar light, we show that the soft-band surface brightness of the hot atmosphere increases rapidly by a factor of ∼30 within the central $\sim\!{10}\ \rm kpc$. The gas temperature drops precipitously to $\lt 0.4\rm \,\, keV$ and the density increases by over an order of magnitude. The remarkably low metallicity here is likely due to photoionization by the quasar emission. The variations in temperature and density are consistent with hydrostatic compression of the hot atmosphere. The extended soft-band peak cannot be explained by an undersubtraction of the quasar or scattered quasar light and is instead due to thermal interstellar medium. The radiative cooling time of the gas falls to only $12\pm 1\rm \,\, Myr$, below the free fall time, and we resolve the sonic radius. H1821+643 is therefore embedded in a cooling flow with a mass deposition rate of up to $3000\ {\rm M}_{\odot}\,{\rm yr}^{-1}$. Multiwavelength observations probing the star-formation rate and cold gas mass are consistent with a cooling flow. We show that the cooling flow extends to much larger radii than can be explained by Compton cooling. Instead, the active galactic nucleus appears to be underheating the core of this cluster.

The infalling elliptical galaxy M89: the chemical composition of the AGN disturbed hot atmosphere

ABSTRACT The chemical enrichment of X-ray-emitting hot atmospheres has hitherto been primarily studied in galaxy clusters. These studies revealed relative abundances of heavy elements that are remarkably similar to Solar. Here, we present measurements of the metal content of M89 (NGC 4552), an elliptical galaxy infalling into the Virgo cluster with a ∼10 kpc ram-pressure stripped X-ray tail. We take advantage of deep Chandra and XMM–Newton observations, and with particular attention to carefully modelling the spectra, we measure the O/Fe, Ne/Fe, Mg/Fe, Si/Fe, and S/Fe ratios. Contrary to previous measurements in galaxy clusters, our results for the hot atmosphere of M89 suggest super-Solar abundance ratios with respect to iron (i.e. α/Fe > 1), similar to its stellar components. Our analysis of the active galactic nucleus (AGN) activity in this system indicates that the AGN-induced outflow could have facilitated the stripping of the original galactic atmosphere, which has been replaced with fresh stellar mass-loss material with super-Solar α/Fe abundance ratios. Additionally, we report a new fitting bias in the RGS data of low-temperature plasma. The measured O/Fe ratios are >1σ lower in multitemperature models than a single temperature fit, leading to discrepancies in the calculations of supernova fractions derived from the metal abundances.

Improved water vapor corrosion resistance of SiC bricks via in situ formation of microporous Yb2Si2O7 bonding phase

AbstractSiC‐based lining refractories used in incinerators faced serious hot water vapor corrosion. The pores in SiC‐based refractories played a crucial role in corrosion resistance because both the penetration of water vapor and the expulsion of corrosion products depended on diffusion channels provided by pores. The in situ microporous Yb2Si2O7 bonding phase formed in the SiC bricks after sintering at 1550°C under air atmosphere, which simultaneously decreased the apparent porosity and pore size. The optimization of pore structures reduced the permeability to gases of SiC bricks by 37.5%, which prevented the penetration of hot water vapor into SiC bricks. The microporous Yb2Si2O7‐bonded SiC bricks presented only .15% permanent linear change and showed good thermal shock resistance after corrosion at 1000°C for 100 h under hot water vapor atmosphere. Some SiC particles in the refractories could be adopted as high‐temperature pore‐forming agents; the gaseous oxidation products of SiC bricks, including SiO(g) and CO(g), contributed to the generation of microporous Yb2Si2O7 (pore size ≤5 μm) and SiC whiskers during sintering, which obviously improved mechanical properties and water vapor corrosion resistance of SiC bricks.