Thermal Component Research Articles

Simulation study of heat transfer behaviour of turbulent two-phase flow in a 3D cubic shell and tube heat exchanger using water and different nanofluids

This research utilizes a two-phase flow model to replicate the thermal exchange in a counter flow shell and tube heat exchanger, comparing the efficacy of different nanofluids against pure water. The shell space is represented as a closed cubic area filled with diverse fluids, while the tube functions as the thermal exchange component. It investigates parameters like nanofluid variations, nanoparticle dimensions, and volume ratios to enhance the efficiency of temperature exchange between the shell and tube fluids. The Reynolds-averaged Navier-Stokes (RANS) technique is employed to analyze turbulence within the heat exchanger, utilizing ANSYS@FLUENT (Version 2022 R1) for simulations, which were considered reliable when convergence criteria reached 10−5. The outcomes are assessed based on velocity, thermal conductivity, Nusselt number, temperature dispersion, and turbulent kinetic energy. Notably, the results underscore that integrating nanoparticles into the fluid amplifies its thermal conductivity, with higher concentrations yielding more significant enhancements. Nanofluids, particularly those comprising SiO2-H2O with small nanoparticles and high volume fractions, exhibit notable improvements in heat transfer compared to pure water. TiO2-H2O follows in second place, trailed by CuO-H2O and Al2O3-H2O. The application of the RANS method effectively elucidates turbulence patterns and their impact on heat transfer dynamics between the shell and tube. An increase in Reynolds number has shown an adverse effect on heat transfer. Overall, this study furnishes valuable insights for optimizing heat transfer performance in such systems.

The role of physical exercise in modifying cardiovascular parameters in hypertensive patients

Hypertension is among the top risk factors for cardiovascular diseases. Diversified rehabilitation programs are needed to limit the progression of the high blood pressure condition. The welfare of aquatic therapy is acknowledged, but hydrotherapeutic procedures are rarely used in cardiovascular diseases. The study aims to assess the impact of an exhaustive hydro-kinetic thermo therapeutic program compared to other methods of treatment, i.e., cardiovascular rehabilitation program, recommendation for a healthy life, and antihypertensive medication. Four groups of patients (46 years ±0,32) diagnosed with hypertension participated in four different rehabilitation programs to analyze the impact on their effort capacity. Their ability to achieve average effort without the appearance of fatigue symptoms was studied for a period of eight weeks by monitoring six parameters: systolic blood pressure (SBP), diastolic blood pressure (DBP), Borg Scale, Medical Research Council Dyspnoea Scale (MRC-DS), pulse (P) and oxygen saturation (O2). Group A, which benefited only of recommendations for a healthy life, didn’t register any significant p values between the initial and final evaluation; group B, which had medications and recommendations for a healthy life, registered significant p values for 2 parameters (SBP and P have p<0.0001); group C, which took part in a cardiovascular rehabilitation program, obtained significant p values for 5 parameters (SBP, DBP, Borg, MRC-DS and O2 have p<0.0001); Group D, the recipient of hydrotherapeutic program, registered significant p values for all statistically 6 monitored parameters (SBP, DBP, Borg, MRC-DS, P and O2 have p<0.0001). Physical activity in water performed regularly within a controlled therapeutic program with the thermal and electrotherapy components, leading to improved capacity for the effort by decreasing blood pressure values and dyspnea parameters.

Numerical investigation on the influence of swirl number to high-temperature zone evolution and outlet temperature distribution in multi-stage combustor

The outlet temperature distribution plays a crucial role in determining the lifespan and stability of downstream thermal components. It poses a significant challenge in the design and regulation of high-temperature combustors. This study aims to investigate the influence of swirl number on the outlet temperature distribution in multi-stage combustor. The impact of varying fourth-stage swirl numbers on flow structure, hot streaks, and temperature distribution is compared and analyzed. The results indicate that increasing the swirl number significantly improves the air–fuel mixing within the combustion zone, leading to the expansion of high-temperature regions. Additionally, the high-temperature region migrates upstream along the primary zone. With an increase in the swirl number, the relative area of hot spots within the combustor also increases. Remarkably, the swirler configuration with a swirl number of 1.5 exhibits the most minimal exit temperature gradient and the highest level of temperature distribution uniformity, quantified by an outlet temperature distribution factor (OTDF) of 0.26. Furthermore, changes in the swirl number affect the distribution of combustion modes within the combustor. Increasing the swirl number promotes the premixed combustion mode at the pilot stage exit and enhances temperature uniformity at the swirler exit. Thorough comprehension of the temperature distribution in the primary zone enables control of the outlet temperature distribution from its origin. Uniformity amplitude (UA) of HCO and primary temperature distribution factor (PTDF) are defined to describe the temperature distribution in primary zone. At a swirl number of 1.5, the UA and PTDF also shows the lowest values of 0.2754 and 0.3019, respectively. Overall, when improving the distribution of HCO under both premixed and non-premixed modes, a more uniform temperature distribution across the primary zone can be achieved, effectively optimize the exit temperature distribution.

High-energy insights from an escaping coronal mass ejection with Solar Orbiter/STIX observations

Solar eruptive events, including solar flares and coronal mass ejections (CMEs), are typically characterised by energetically significant X-ray emissions from flare-accelerated electrons and hot thermal plasmas. However, the intense brightness of solar flares often overshadows high-coronal X-ray emissions from the associated eruptions due to the limited dynamic range of current instrumentation. Occulted events, where the main flare is blocked by the solar limb, provide an opportunity to observe and analyse the X-ray emissions specifically associated with CMEs. This study investigates the X-ray and extreme ultraviolet (EUV) emissions associated with a large filament eruption and CME that occurred on February 15, 2022. This event was highly occulted from the three vantage points of Solar Orbiter (sim 45$^ circ $ behind the limb), Solar–TErrestrial RElations Observatory (STEREO-A), and Earth. We utilised X-ray observations from the Spectrometer/Telescope for Imaging X-rays (STIX) and EUV observations from the Full Sun Imager (FSI) of the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter, supplemented by multi-viewpoint observations from STEREO-A/Extreme-UltraViolet Imager (EUVI). This enabled a comprehensive analysis of the X-ray emissions in relation to the filament structure observed in the EUV. We used STIX's imaging and spectroscopy capabilities to characterise the X-ray source associated with the eruption. Our analysis reveals that the X-ray emissions associated with the occulted eruption originate from an altitude exceeding 0.3 \(R_ above the main flare site. The X-ray time profile shows a sharp increase and exponential decay, and consists of both a hot thermal component at 17pm 2 MK and non-thermal emissions ($>11.4 keV) characterised by an electron spectral index of 3.9pm 0.2. Imaging analysis shows an extended X-ray source that coincides with the EUV emission as observed from EUI, and was imaged until the source grew to a size exceeding the STIX imaging limit (180 arcsec). Filament eruptions and associated CMEs have hot and non-thermal components, and the associated X-ray emissions are energetically significant. Our findings demonstrate that STIX combined with EUI provides a unique and powerful tool for examining the energetic properties of the CME component of solar energetic eruptions. Multi-viewpoint and multi-instrument observations are crucial for revealing such energetically significant sources in solar eruptions that might otherwise remain obscured.

Enhanced temperature regulation in compound heating systems: Leveraging guided policy search and model predictive control

With the widespread application of solar-energy-air-source heat pump composite heating, optimizing the regulation of air temperature in heating zones, enhancing system thermal comfort, and reducing energy consumption have become crucial. To ensure residential comfort while minimizing HVAC system energy costs, a control method combining guided policy search (GPS) with model predictive control (MPC) is proposed for composite heating systems. This method replaces state estimation in MPC with policy search and substitutes the offline trajectory optimization used in guided policy search with MPC, thus integrating the strengths of both approaches. This strategy not only improves control precision but also reduces energy consumption and enhances system robustness. The GPS-MPC control algorithm was validated against reinforcement learning and MPC. A simulation model was developed and validated on a real physical platform. Simulations compared the control effects of on-off control and MPC on pump frequency, flow rate, stratified thermal storage tank temperature, component, and system energy consumption. The data results indicate that the GPS-MPC algorithm offers superior predictive accuracy, efficiency, and robustness in composite heating control systems compared to conventional methods. Under the GPS-MPC strategy, indoor temperature fluctuations, pump frequency response speed, and energy consumption were significantly improved, with temperature fluctuation limited to only 0.8 °C, and the system achieving energy savings of over 12 %.

Ablation resistance of C/C–Hf1-xZrxC composites under an oxyacetylene flame at above 2700 °C

To the better application of C/C composites in thermal components of vehicles above 2700 °C, C/C–Hf1-xZrxC composites were prepared by CLVD, and the ablation behavior of composites was investigated. The results show that C/C–Hf0.5Zr0.5C has excellent ablation properties with linear and mass ablation rates of −0.23 μm/s and −0.31 mg/(s·cm2), respectively. ZrO2 molten phase and HfxZr1-xO2 particles are generated on the surface of C/C–Hf1-xZrxC composites during ablation. During the ablation process, defects are healed by the ZrO2 molten phase due to its mobility, which inhibits the diffusion of oxygen into the substrate. The ZrO2 molten phase is stabilized by the pinning effect of the HfxZr1-xO2 particles, which makes the ZrO2 molten phase better resistant to the scouring of the air stream. A relatively complete oxide layer is generated on the C/C–Hf0.5Zr0.5C surface, with a moderate amount of HfxZr1-xO2 exerting a pinning effect to hold the ZrO2 molten phase.

Probing the energy and luminosity-dependent spectro-timing properties of RX J0440.9+4431 with AstroSat

ABSTRACT The Be/X-ray binary pulsar RX J0440.9+4431 went through a giant outburst in December 2022 with a peak flux of $\sim$2.3 Crab in 15–50 keV. We studied the broad-band timing and spectral properties of RX J0440.9+4431 using four AstroSat observations, where the source transited between subcritical and supercritical accretion regimes. Pulsations were detected significantly above 100 keV. The pulse profiles were found to be highly luminosity- and energy-dependent. A significant evolution in the pulse profile shape near the peak of the outburst indicates a possible change in the accretion mode and beaming patterns of RX J0440.9+4431. The rms pulsed fraction was luminosity- and energy-dependent, with a concave-like feature around 20–30 keV. The depth of this feature varied with luminosity, indicating changes in the accretion column height and proportion of reflected photons. The broad-band continuum spectra were best fitted with a two-component Comptonization model with a blackbody component or a two-blackbody component model with a thermal Comptonization component. A quasi-periodic oscillation (QPO) at 60 mHz was detected at a luminosity of $2.6 \times 10^{37}$ erg s$^{-1}$, which evolved into 42 mHz at $1.5 \times 10^{37}$ erg s$^{-1}$. The QPO rms were found to be energy dependent with an overall increasing trend with energy. For the first time, we found the QPO frequency varying with photon energy in an X-ray pulsar, which poses a challenge in explaining the QPO with current models such as the Keplarian and beat frequency model. Hence, more physically motivated models are required to understand the physical mechanism behind the mHz QPOs.

Thermally Conductive Polydimethylsiloxane-Based Composite with a Three-Dimensional Vertically Aligned Thermal Network Incorporating Hexagonal Boron Nitride Nanosheets and Nanodiamonds.

Thermal interface materials play a pivotal role in efficiently transferring heat from heating devices to thermal management components, thereby reducing the risk of component degradation due to overheating. In this study, we propose a strategy for enhancing the out-of-plane thermal conductivity (TC) of composite materials by fabricating a three-dimensional (3D) thermal network within a polydimethylsiloxane (PDMS) matrix. Specifically, the composite material was designed to incorporate a dense thermal network comprising hexagonal boron nitride nanosheets (BNNSs) and nanodiamonds (NDs). The fabrication process commenced with the preparation of BNNSs through liquid-phase exfoliation, followed by the creation of a 3D BNNSs-NDs/polyimide aerogel thermal framework using a unidirectional solidification ice templating method and subsequent heat treatment. Vacuum impregnation and curing were then employed to finalize the production of the 3D BNNSs-NDs/PDMS composite material. Characterization analyses indicated that the addition of NDs filled the voids between BNNSs, leading to the densification of the thermal framework pore walls and the establishment of additional thermal pathways. Impressively, with concentrations of BNNSs and NDs of 17.99 and 7.71 wt %, respectively, the out-of-plane TC of the 3D BNNSs-NDs/PDMS composite material reached 1.623 W m-1 K-1, marking notable enhancements of 754.21% and 256.70% compared to those of pure PDMS and composites prepared via direct blending with randomly distributed BNNSs and NDs, respectively. Furthermore, the 3D BNNSs-NDs thermal framework improved the compressive strength and the dimensional stability of the composite material. Finite element simulations additionally confirmed the synergistic improvement of the TC achieved through the combination of BNNSs and NDs, demonstrating that the 3D BNNSs-NDs/PDMS composite material displayed superior heat conduction and a greater density of thermal pathways compared to those of its counterparts, including 3D BNNSs/PDMS and 3D NDs/PDMS composite materials. In summary, this work presents a strategy for enhancing the out-of-plane TC of polymer-based composite materials by incorporating vertically aligned thermal networks.

Atom number fluctuations in Bose gases—statistical analysis of parameter estimation

Abstract The investigation of atom number fluctuations in quantum gases at finite temperatures showcases the ongoing challenges in understanding complex quantum systems. Recently, the microcanonical nature of atom number fluctuations in weakly interacting Bose-Einstein condensates was observed. This motivates an investigation of the thermal component of partially condensed Bose gases, due to the conservation of the total atom number.

Here, we present a combined analysis of both components, including a comprehensive analysis of the uncertainties in the preparation and parameter extraction of partially condensed quantum gases. This enables a complementary observation of the thermal atom number fluctuations and yields and improved value of the peak BEC atom number fluctuations $\Delta N_\mathrm{p,0}^2 =(3.7\pm7)\times10^5$ close to the critical temperature. This corresponds to a reduction by \SI{41}{\percent} with respect to previous analysis and corroborates the microcanonical nature of the fluctuations.

The analysis of noise contributions due to the preparation and evaluation of partially condensed Bose gases is based on Monte Carlo simulations of optical density profiles. Importantly, this allows for an estimation of the technical noise contributions to the atom number and temperature, which is generally applicable in the field of ultracold atoms.

GRB 190114C: Fireball Energy Budget and Radiative Efficiency Revisited

The jet composition of gamma-ray bursts (GRBs), as well as how efficiently the jet converts its energy to radiation, are long-standing problems in GRB physics. Here, we reported a comprehensive temporal and spectral analysis of the TeV-emitting bright GRB 190114C. Its high fluence (∼4.4 × 10−4 erg cm−2) allows us to conduct the time-resolved spectral analysis in great detail and study their variations down to a very short timescale (∼0.1 s) while preserving a high significance. Its prompt emission consists of three well-separated pulses. The first two main pulses (P 1 and P 2) exhibit independently strong thermal components, starting from the third pulse (P 3) and extending to the entire afterglow, the spectra are all nonthermal, and the synchrotron plus Compton upscattering model well interprets the observation. By combining the thermal (P 1 and P 2) and the nonthermal (P 3) observations based on two different scenarios (global and pulse properties) and following the method described in Zhang et al., we measure the fireball parameters and GRB radiative efficiency with little uncertainties for this GRB. A relevantly high GRB radiative efficiency is obtained based on both the global and pulse properties, suggesting that if GRBs are powered by fireballs, the efficiency can sometimes be high. More interestingly, though the observed parameters are individually different (e.g., the amount of mass loading M), the radiative efficiency obtained from P 1 (η γ = 36.0% ± 6.5%) and P 2 (η γ = 41.1% ± 1.9%) is roughly the same, which implies that the central engine of the same GRB has some common properties.

Devising a calculation method for modern structures of current-conducting elements in large electric machines in a three-dimensional statement

The jumpers of rotor pole-to-pole connections are highly stressed elements in a hydraulic generator structure. These assemblies often fail due to deformation that exceeds the size of an air gap. Existing methods do not take into account the thermal component and attempts to improve the design are not based on mathematical models that make it possible to perform calculations with an accuracy of more than 50 %. The method devised in this work makes it possible to obtain boundary conditions of the third kind on the basis of three-dimensional mathematical modeling of the ventilation system of the hydraulic unit without simplifications. The method accuracy is explained by taking into account the spatial thermal component. The heat transfer coefficient determined by this method in the pole-to-pole connections area was ~250 W/(m2·K). Using FEM, mathematical modeling of the thermal stress state of pole-to-pole connections was carried out, taking into account mechanical and thermal factors. This made it possible to design the improved connection structure with additional fastening elements, which make it possible to reduce the displacement to 0.03 mm, and the stress to 53 MPa at the rotor rotation frequency of 880 rpm. This design makes it possible to enable reliable operation of the hydraulic unit under the condition of increasing the rotor rotation frequency to overspeed with disconnected combinatorial dependence, provided that the actual stresses are 0.95 % of the material yield strength. The convergence of the values obtained by the proposed method and by the HSS method exceeded 99 %. The practical result is the proposals for the hydraulic generator design modernization

Magnetization Factors of Gamma-Ray Burst Jets Revealed by a Systematic Analysis of the Fermi Sample

The composition of gamma-ray burst (GRB) jets remained a mystery until recently. In practice, we usually characterize the magnetization of the GRB jets (σ 0) through the ratio between the Poynting flux and matter (baryonic) flux. With the increasing value of σ 0, magnetic energy gradually takes on a dominant role in the acceleration and energy dissipation of the jet, causing the proportion of thermal component in the prompt-emission spectrum of GRBs to gradually decrease or even be completely suppressed. In this work, we conducted an extensive analysis of the time-resolved spectrum for all Fermi GRBs with known redshift, and we diagnose σ 0 for each time bin by contrasting the thermal and nonthermal radiation components. Our results suggest that most GRB jets should contain a significant magnetic energy component, likely with magnetization factors σ 0 ≥ 10. The value of σ 0 seems to vary significantly within the same GRB. Future studies with more samples, especially those with lower-energy spectral information coverage, will further verify our results.

Numerical investigation of liquid oxygen filling process in liquid rocket engine by a multi-dimensional co-simulation method

The liquid oxygen filling process in the thermal component downstream of the valve directly affects the starting performance and working reliability of the liquid rocket engine. The filling process is reproduced with a multi-dimensional co-simulation method including one-dimensional system simulation and three-dimensional component simulation, the former provides dynamic flow data for the latter to calculate the filling process. The characteristics of the flow and evaporation and the phenomenon of gaseous oxygen residue are investigated. The results indicate that the simulated pressure value and tendency in the thermal component agree well with the experiment. The flow and evaporation reach a temporary equilibrium due to the flash boiling of the superheated liquid oxygen in the thermal component. The pressure in the combustion chamber downstream of the thermal component plays an important role in breaking the equilibrium and promoting the transition from superheat to supercool state of liquid oxygen. Additionally, the volume proportion of residue gaseous oxygen is 35 % at ignition time, which is far from the ideal state and affects the temperature measurement in the experiment. 26 % of the gaseous oxygen has not been discharged in time, leading to the injection instability in the injection region away from the inlet.

Resource utilization of coal-derived sludge and low-rank coal by multi-step thermochemical co-treatment method

Both coal-derived sludge and low-rank coal possess significant potential for resource utilization and have garnered considerable attention in recent years. The TG−DTG analysis method showed that the thermal conversion components of coal-derived sludge tended to migrate to coal and interacted with low-rank coal. The dewatering effect of low-rank coal on coal-derived sludge was investigated using the sludge-specific resistance to filtration (SRF) method. The results showed that the addition of coal promoted the transformation of interstitial water and surface water of sludge, especially the interstitial water to free water. Dewatering and deoxidation of low-rank coal and coal-derived sludge were realized by decarboxylation and C−O bond cleavage on benzene during hydrothermal co-treatment at 140−220 ℃. The average water content of hydrochar was 3.96 % after hydrothermal co-treatment, and its calorific value increased from 19.77 MJ/kg to 21.74 MJ/kg after hydrothermal co-treatment. Hydrothermal oil was produced during hydrothermal co-treatment. GC−MS analysis showed that the contents of N and S increased in the hydrothermal oil with the increase of hydrothermal temperature, indicating that the hydrothermal co-treatment can remove the impurity elements (such as N and S) contained in coal-derived sludge and low-rank coal. The pyrolysis experiments of the hydrochar at 600–900 ℃ showed that the hydrochar produced less pyrolysis gas and emitted less CO2 than the result without hydrothermal co-treatment. This study provided an effective strategy for the treatment and resource utilization of sludge and coal.

Advanced eco-friendly power and cooling cogeneration-thermal energy storage utilizing phase change materials and chemisorption in renewable-based configurations

Increasing the reliability, stability, and safety of renewable energy systems depends on the integration of energy storage systems in order to balance energy production and demand. This research introduces an innovative system that combines a chemisorption unit, a phase change material (PCM)-based thermal energy storage (TES) mechanism, and a solar thermal unit with Linear Fresnel Reflectors (LFRs), tailored for residential usage. The system’s performance and dynamics are examined using TRNSYS and MATLAB software tools. Within this system, electricity is produced via a turbine propelled by the pressure differential created by chemical reactions within a chemisorption unit. Concurrently, cooling was facilitated through the ammonia evaporation process within an evaporator. At heat source temperatures between 100–200 °C, the system achieved a maximum electricity output of 2,718.9 W and a cooling rate of 14,601.5 W. The energy efficiency peaked at 46.32 %, and exergy efficiency at 40.78 %. The thermal energy storage component, with a volume of 1.5 m3, achieved a maximum storage capacity of 253.7 kWh. The study shows that higher heat source temperatures enhance production capacity but reduce the coefficient of performance (COP) for cooling by approximately 25 %. Overall, the system demonstrates significant potential for improving the efficiency and reliability of renewable energy systems.

Ablation and mechanical behavior of reusable Cf/SiC-ZrC with a gradient-structured matrix produced by reactive melt infiltration

Cf/SiC-ZrC renowned for its outstanding performance as a thermal protectant, has gaining widespread recognition. Recent research on this system has emphasized the development of a cost-effective and reusable version with increased thickness for extended use in thick-walled thermal structural components. Ablation resistance, high strength retention, and high thermal conductivity are crucial for successful aircraft reentry. In this study, a low-cost reactive melt infiltration (RMI) method is developed for preparing dense and high-performance large-thickness Cf/SiC-ZrC (L-Cf/SiC-ZrC) with a gradient-structured matrix. The use of a fine weave-pierced fabric preform structure enhances both the structural integrity and thermal conductivity of Cf/SiC-ZrC in the thickness direction. Simultaneously, the gradient-structured matrix, with appropriate contents of surficial ZrC and SiC exhibits erosion resistance, where the internal core with a high SiC content ensures remarkable strength retention. This unique matrix-structure design is achieved by integrating porous C with a single-stage pore structure and a high degree of graphitization degree, and a Si-Zr alloy with a unique composition. The 20 mm thick Cf/SiC-ZrC obtained via RMI has a density of 2.79 g/cm3 with an open porosity of 5.65 % and flexural strength of 224.3 ± 5.4 MPa. Under a heat flux of 4.186 MW/m2, Cf/SiC-ZrC exhibits an ablation rate of −0.004 mm/s after 60 s, demonstrating its resilience against ablation damage. Moreover, the post-ablation strength (166.0 ± 4.4 MPa) exceeds that of reported Cf/SiC-ZrC congeners, highlighting the robust load-bearing capability.

Quantifying local lattice distortions in refractory high-entropy alloys

Severe local lattice distortions (LLDs), originating from the size mismatch among atoms, have been proposed as one of the key mechanisms responsible for the excellent mechanical properties of bcc-structured high-entropy alloys (HEAs). They have also been connected to phase stability, as well as physical properties such as electrical conductivity. Experimental measurements of LLDs are, however, difficult and often ambiguous. Analysis of total scattering data in real space has been proposed to provide a uniquely suitable probe of LLDs, but its widespread application and validation are still limited. We conduct a thorough study of LLD measurements in refractory high-entropy alloys (RHEAs) using small-box pair distribution function (PDF) analysis. We start by reexamining existing literature data using a recently proposed coherent theoretical framework to demonstrate that LLDs in RHEAs can indeed be considered as severe and can be reliably measured even in the absence of known thermal components. We perform total scattering experiments of a typical RHEA (HfNbTaTiZr) using both x-rays and neutrons, and show that real-space PDF analysis of data from different types of radiation gives consistent values of LLDs. The results are also in good agreement with the values derived from reciprocal-space data. Finally, through simulation and analysis of theoretical two-phase PDFs, we demonstrate that the effect of the chemical segregation in the investigated RHEA on the measured LLDs is limited when dealing with comparatively large LLDs. The results show that PDF analysis using small-box modeling provides a fast and reliable tool for measuring LLDs in RHEAs, which makes it ideal for analysis of large data sets from time-resolved measurements. Published by the American Physical Society 2024

ISLAT: the Interactive Spectral-line Analysis Tool for JWST and Beyond

We present the Interactive Spectral-Line Analysis Tool (iSLAT), a python-based graphical tool that allows users to interactively explore, inspect, and fit line emission observed in molecular spectra. iSLAT adopts a simple slab model in LTE that simulates emission spectra with a small set of parameters (temperature, emitting area, column density, and line broadening) that users can adjust in real time for multiple molecules or multiple thermal components of a same molecule. A central feature of iSLAT is the possibility to interactively inspect individual lines or line clusters to visualize their properties at high resolution and identify them in the population diagram. iSLAT provides a number of additional features, including the option to identify lines that are not blended at the instrumental resolution, the possibility to save custom line lists selected by the user, and to fit and measure their properties (line flux, width, and centroid) for later analysis. In this paper we launch the tool and demonstrate it on infrared spectra from the James Webb Space Telescope and ground-based instruments that provide higher resolving power. We also share curated line lists that are useful for the analysis of the forest of water emission lines observed from protoplanetary disks. iSLAT is shared with the community on GitHub.

In-orbit detection of the spectral smile for the Mars Mineral Spectrometer

As a payload of Tianwen-1 (TW-1), the Mars Mineral Spectrometer (MMS) is tasked with acquiring hyperspectral data of the Martian surface to detect material composition. Microdeformations in optical, mechanical, and thermal components result in the MMS experiencing spectral response distortion in orbit, leading to systematic changes in pixel central wavelengths and full width at half maximum (FWHM). Known as the spectral smile, this distortion compromises the accuracy of reflectance inversion and material composition detection. This study introduces a method for detecting the spectral smile through the Martian atmospheric absorption channel, capitalizing on the distinct characteristics of the atmospheric composition and absorption patterns of Mars. A suitable technical route for in-orbit spectral smile detection was established and tested using simulation experiments and MMS-acquired hyperspectral data. Results suggest that the proposed method can attain central wavelength shifts with a maximum error of 0.32 nm and FWHM variations with a maximum error of 1.95 nm. Employing in-orbit spectral smile detection markedly enhances the correction of Martian atmospheric absorption and provides technical support for Martian surface reflectance inversion. https://github.com/wubingnote/MMS-Spectral-Smile.

EROSITA narrowband maps at the energies of soft X-ray emission lines

Hot plasma plays a crucial role in regulating the baryon cycle within the Milky Way, flowing from the energetic sources in the Galactic center and plane, to the corona and the halo. This hot plasma represents an important fraction of the Galactic baryons, plays a key role in galactic outflows and is an important ingredient in galaxy evolution models. Taking advantage of the Spectrum-Roentgen-Gamma (SRG first all-sky survey (eRASS1), in this work our aim is to provide a panoramic view of the hot circumgalactic medium (CGM) of the Milky Way. Compared to the previous all-sky X-ray survey performed by ROSAT, the improved energy resolution of enabled us to map, for the first time, the sky within the narrow energy bands characteristic of soft X-ray emission lines. These lines provide essential information on the physical properties of the hot plasma. Here we present the eRASS1\ half sky maps in narrow energy bands corresponding to the most prominent soft X-ray lines and which allowed us to constrain the distribution of the hot plasma within and surrounding the Milky Way. We corrected the maps by removing the expected contribution associated with the cosmic X-ray background, the time-variable solar wind charge exchange, and the local hot bubble. We applied corrections to mitigate the effect of absorption, therefore highlighting the emission from the CGM of the Milky Way. We used the line ratio of the oxygen lines as a proxy to constrain the temperature of the warm-hot CGM, and we defined a pseudo-temperature $ T $ map. The map highlights how different regions are dominated by different thermal components. Toward the outer halo, the temperature distribution of the CGM on angular scales of 2--20 deg is consistent with being constant $ T T 4<!PCT!>$ with a marginal detection of $ T T = 2.7 <!PCT!> 0.2<!PCT!>$ (statistical) $ 0.6<!PCT!>$ (systematic) in the southern hemisphere. Instead significant variations of $ 12<!PCT!>$ are observed on scales of many tens of degrees when comparing the northern and southern hemispheres. The pseudo-temperature map shows significant variations across the borders of the bubbles, suggesting temperature variations, possibly linked to shocks, between the interior of the Galactic outflow and the unperturbed CGM. In particular, a shell characterized by a lower line ratio appears close to the edge of the bubbles.