Cooler Component Research Articles

Metallicity-dependent kinematics and orbits in the Milky Way’s nuclear stellar disc

Context. The nuclear stellar disc (NSD) is a flat and dense stellar structure at the centre of the Milky Way. Previous work has identified the presence of metal-rich and metal-poor stars in the NSD, suggesting that they have different origins. The recent publication of photometric, metallicity, proper motion, and orbital catalogues allows the NSD stellar population to be characterised with unprecedented detail. Aims. We aim to explore the proper motions and orbits of NSD stars with different metallicities to assess whether they have different origins and to better understand the metallicity distribution in the NSD. Methods. We distinguished between metal-rich and metal-poor stars by applying a Gaussian mixture model, as done in previous work, and analysed the proper motions, orbits, and spatial distribution of stars with different metallicities. Results. We find that metal-rich stars exhibit a lower velocity dispersion, suggesting that they trace a kinematically cooler component compared to metal-poor ones. Furthermore, z-tube orbits are predominant among metal-rich stars, while chaotic/box orbits are more common among metal-poor ones. We also find that metal-rich and metal-poor stars show a similar extinction and are present throughout the analysed regions. As a secondary result, we detected a metallicity gradient in the metal-rich population with higher metallicity towards the centre of the NSD and a tentative gradient for the metal-poor stars, which is consistent with previous studies that did not distinguish between the two populations. Conclusions. Our results suggest that metal-rich stars trace the NSD, whereas metal-poor ones are related to the Galactic bar and probably constitute Galactic bar interlopers and/or are NSD stars that originated from accreted clusters. The detected metallicity gradients aligns with the currently accepted inside-out formation of the NSD.

Decomposing the AIA 304 Å Channel into Its Cool and Hot Components

The AIA 304 Å channel on board the Solar Dynamics Observatory (SDO) offers a unique view of ≈105 K\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$\\approx 10^{5}\ ext{ K}$\\end{document} plasma emitting in the He ii 304 Å line. However, when observing off-limb, the emission of the (small) cool structures in the solar atmosphere (such as spicules, coronal rain and prominence material) can be of the same order as the surrounding hot coronal emission from other spectral lines included in the 304 Å passband, particularly over active regions. In this paper, we investigate three methods based on temperature and morphology that are able to distinguish the cool and hot emission within the 304 Å passband. The methods are based on the Differential Emission Measure (DEM), a linear decomposition of the AIA response functions (RFit) and the Blind Source Separation (BSS) technique. All three methods are found to produce satisfactory results in both quiescent and flaring conditions, largely removing the diffuse corona and leading to images with cool material off-limb in sharp contrast with the background. We compare our results with co-aligned data from the Interface Region Imaging Spectrograph (IRIS) in the SJI 1400 Å and 2796 Å channels, and find the RFit method to best match the quantity and evolution of the cool material detected with IRIS. Some differences can appear due to plasma emitting in the logT=5.1–5.5\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$\\log T=5.1\\,\ ext{--}\\,5.5$\\end{document} temperature range, particularly during the catastrophic cooling stage prior to rain appearance during flares. These methods are, in principle, applicable to any passband from any instrument suffering from similar cool and hot emission ambiguity, as long as there is good coverage of the high-temperature range.

Enhanced Thermoelectric Generator and Cooler for Boiler Cooling Efficiency Improvement

In this project to enhance the overall efficiency of boiler cooling systems, by incorporating thermoelectric technology, this project seeks to optimize energy utilization and reduce waste heat in the boiler cooling process. The thermoelectric generator and cooler utilize the Seebeck effect to convert waste heat into usable electrical energy. This generated electricity can be utilized for various purposes within the boiler system, thereby reducing the reliance on external power sources. Additionally, the thermoelectric cooler component helps to enhance the cooling efficiency of the boiler system. By actively removing excess heat from critical components, it prevents overheating and improves overall performance. The integration of thermoelectric technology in boiler cooling systems has the potential to significantly improve energy efficiency, reduce operational costs, and minimize environmental impact. This project abstract provides an overview of the objectives and benefits of implementing thermoelectric generators and coolers in boiler cooling systems.

Probing the soft X-ray properties and multi-wavelength variability of SN2023ixf and its progenitor

Abstract We present a detailed analysis of nearly two decades of optical/UV and X-ray data to study the multi-wavelength pre-explosion properties and post-explosion X-ray properties of nearby SN2023ixf located in M101. We find no evidence of precursor activity in the optical to UV down to a luminosity of $\lesssim$ $1.0\times10^{5}\, \textrm{L}_{\odot}$ , while X-ray observations covering nearly 18 yr prior to explosion show no evidence of luminous precursor X-ray emission down to an absorbed 0.3–10.0 keV X-ray luminosity of $\sim$ $6\times10^{36}$ erg s $^{-1}$ . Extensive Swift observations taken post-explosion did not detect soft X-ray emission from SN2023ixf within the first $\sim$ 3.3 days after first light, which suggests a mass-loss rate for the progenitor of $\lesssim$ $5\times10^{-4}\,\textrm{M}_{\odot}$ yr $^{-1}$ or a radius of $\lesssim$ $4\times10^{15}$ cm for the circumstellar material. Our analysis also suggests that if the progenitor underwent a mass-loss episode, this had to occur $>$ 0.5–1.5 yr prior to explosion, consistent with previous estimates. Swift detected soft X-rays from SN2023ixf $\sim$ $4.25$ days after first light, and it rose to a peak luminosity of $\sim10^{39}$ erg s $^{-1}$ after 10 days and has maintained this luminosity for nearly 50 days post first light. This peak luminosity is lower than expected, given the evidence that SN2023ixf is interacting with dense material. However, this might be a natural consequence of an asymmetric circumstellar medium. X-ray spectra derived from merging all Swift observations over the first 50 days are best described by a two-component bremsstrahlung model consisting of a heavily absorbed and hotter component similar to that found using NuSTAR, and a less-absorbed, cooler component. We suggest that this soft component arises from cooling of the forward shock similar to that found in Type IIn SN2010jl.

The First Multiband Photometric Light Curve Solutions of the V Gru Binary System from the Southern Hemisphere

The first multiband photometric solutions of the short-period V Gru eclipsing binary from the southern hemisphere are presented in this study. Light curves of the system were observed through BVI filters at the Congarinni Observatory in Australia for 15 nights. In addition to the new ground-based data, we also used the TESS observations in two sectors. We analyzed the light curves of the system using the PHysics Of Eclipsing BinariEs (PHOEBE) 2.4.7 version code to achieve the best accordance with the photometric observations. The solutions suggest that V Gru is a near-contact binary system with q = 1.302(81) mass ratio, f 1 = 0.010(23), f 2 = −0.0.009(21), and i = 73.45(38). We considered the two hot spots on the hotter and cooler components for the light curve analysis. We extracted the minima times from the light curves based on the Markov Chain Monte Carlo (MCMC) approach. Using our new light curves, TESS, and additional literature minima, we computed the ephemeris of V Gru. The system’s eclipse timing variation trend was determined using the MCMC method. This system is a good and challenging case for future studies.

Temperature of quiet Sun small scale brightenings observed by EUI on board Solar Orbiter: Evidence for a cooler component

Context. On May 30, 2020, small and short-lived extreme-UV (EUV) brightenings in the quiet Sun were observed over a four-minute sequence by the EUV channel of the Extreme Ultraviolet Imager – High Resolution Imager (EUIHRIEUV) on board the Solar Orbiter. The brightenings’ physical origin and possible impact on coronal or transition region (TR) heating are still to be determined. Aims. Our aim is to derive the statistical thermal evolution of these events in order to establish their coronal or TR origin. Methods. Our thermal analysis took advantage of the multithermal sensitivity of the Atmospheric Imaging Assembly (AIA) imager on board the Solar Dynamics Observatory. We first identified the HRIEUV events in the six coronal bands of AIA. We then performed a statistical time lag analysis that quantified the delays between the light curves from different bands, as these time lags can give significant insight into the temperature evolution of the events. The analysis was performed taking into account the possible contribution of the background and foreground emissions to the results. Results. For all nine couples of AIA bands analyzed, the brightening events are characterized by time lags inferior to the AIA cadence of 12 s. Our interpretation for these short time lags is the possible copresence of events that reach or do not reach coronal temperatures (≈1 MK). We believe that the cool population dominates the events analyzed in this work.

Effects of Internal Heat Exchanger on Two-Stage Compression Trans-Critical CO2 Refrigeration Cycle Combined with Expander and Intercooling

Because of the limitations of traditional refrigerants, the application of trans-critical CO2 technology in domestic gas conditioners and other fields is becoming increasingly popular. This paper proposes a new CO2 trans-critical refrigeration system. Combining the internal heat exchanger and expander components, as well as the two-stage compression cycle, we analyzed the effectiveness of the expander, internal heat exchanger, and intercooling on system performance under various operating conditions in terms of energy, exergy analysis, and optimal discharge pressure. The system performance can be changed by changing the cycle conditions and internal heat exchanger effectiveness, which reduces system power consumption and the percentage of exergy losses of gas cooler components. Compared to the single-stage compression with expander cycle, the systems cycle power consumption is reduced by 2–15.7% and the maximum system COP is increased by 2.93–6.93%. From the view of energy effectiveness, the system’s maximum COP increases by 3.9% and the percentage of exergy losses of gas cooler decreases by 22.5% with the effectiveness of internal heat exchanger varying. The addition of an internal heat exchanger has resulted in improved system performance, which is important for providing a relevant cycle model for the application.

Soft X-Ray Spectral Diagnostics of Multithermal Plasma in Solar Flares with Chandrayaan-2 XSM

Spectroscopic observations in X-ray wavelengths provide excellent diagnostics of the temperature distribution in solar flare plasma. The Solar X-ray Monitor (XSM) on board the Chandrayaan-2 mission provides broadband disk-integrated soft X-ray solar spectral measurements in the energy range of 1–15 keV with high spectral resolution and time cadence. In this study, we analyze the X-ray spectra of three representative GOES C-class flares obtained with the XSM to investigate the evolution of various plasma parameters during the course of the flares. Using the soft X-ray spectra consisting of the continuum and well-resolved line complexes of major elements like Mg, Si, and Fe, we investigate the validity of the isothermal and multithermal assumptions on the high-temperature components of the flaring plasma. We show that the soft X-ray spectra during the impulsive phase of the high-intensity flares are inconsistent with isothermal models and are best fitted with double-peaked differential emission measure distributions where the temperature of the hotter component rises faster than that of the cooler component. The two distinct temperature components observed in differential emission measure models during the impulsive phase of the flares suggest the presence of the directly heated plasma in the corona and evaporated plasma from the chromospheric footpoints. We also find that the abundances of low first ionization potential elements Mg, Si, and Fe reduce from near coronal to near photospheric values during the rising phase of the flare and recover back to coronal values during the decay phase, which is also consistent with the chromospheric evaporation scenario.

Spectral variability in NGC 1042 ULX1

ABSTRACT We report X-ray spectral variability in an ultraluminous X-ray source NGC 1042 ULX1, using archival XMM-Newton and recent NuSTAR observations. In long-term evolution, the source has shown a trend of variation in spectral hardness. The variability in different XMM-Newton observations is prominent above ∼1 keV. Cool thermal disc component with a characteristic temperature of ∼0.2 keV manifests that the spectral state of NGC 1042 ULX1 in all epochs is similar to that of the ultraluminous state sources. An apparent anti-correlation between luminosity and power-law index demonstrates that the source becomes spectrally harder when it is in a brighter state. That is conceivably related to variation in accretion rate, strength of Comptonization, wind/outflow in the system or a manifestation of varying disc occultation. Typical hard ultraluminous-type spectra indicate that NGC 1042 ULX1 is a low inclination system in general. Spectral properties suggest that, like many other ULXs which show spectral curvature around ∼6–10 keV, NGC 1042 ULX1 could be another stellar-mass super-Eddington accretor.

Widespread Detection of Two Components in the Hot Circumgalactic Medium of the Milky Way

Surrounding the Milky Way (MW) is the circumgalactic medium (CGM), an extended reservoir of hot gas that has significant implications for the evolution of the MW. We used the HaloSat all-sky survey to study the CGM’s soft X-ray emission in order to better define its distribution and structure. We extend a previous HaloSat study of the southern CGM (Galactic latitude b < −30°) to include the northern CGM (b > 30°) and find evidence that at least two hot gas model components at different temperatures are required to produce the observed emission. The cooler component has a typical temperature of kT ∼0.18 keV, while the hotter component has a typical temperature of kT ∼0.7 keV. The emission measure in both the warm and hot components has a wide range (∼0.005–0.03, and ∼0.0005–0.004 cm−6 pc, respectively), indicating that the CGM is clumpy. A patch of relatively consistent CGM was found in the north, allowing for the CGM spectrum to be studied in finer detail using a stacked spectrum. The stacked spectrum is well described with a model including two hot gas components at temperatures of kT = 0.166 ± 0.005 keV and kT = keV. As an alternative to adding a hot component, a neon-enhanced single-temperature model of the CGM was also tested and found to have worse fit statistics and poor residuals.

Orbital Period Changes of Selected Two Semi-Deteached Binaries

Since the data obtained from satellite data are very sensitive, the minima times of the target systems have obtained from Kepler (K2) and TESS observations. A total of 14 minima times were obtained from Kepler (K2) data for the AF Gem system and 11 minima times in two different sectors from the TESS data for the RY Gem system. In this study, orbital period behaviors of semi-detached binaries (SDBs) AF Gem and RY Gem systems have investigated, together with minima times obtained from literature and satellite data. It has been observed that the orbital periods of AF Gem and RY Gem decrease. The period change rates of AF Gem and RY Gem systems are determined as -4.1×10-8 and -6.5×10-6 day/ year. The magnetic activity of the cooler components of the systems may be the reason for the periods decrease, and therefore the mass loss rates of the systems have calculated. For AF Gem and RY Gem, mass loss rate was found to be -4.4×10-8 M⊙/year and -8.2×10-7 M⊙/year, respectively. In the O-C graph of AF Gem, sinüsoidal variations also exist. Sinusoidal change may be demonstrated as being the result of a light time effect (LITE) via a tertiary body around the eclipsing pair. The minimum mass of probable third star around AF Gem has found to be 0.24 M⊙.

SN 1987A: Tracing the flux decline and spectral evolution through a comparison of SRG/eROSITA and XMM-Newton observations

Context. SN 1987A is the supernova closest to us observed in the past four centuries. It provides the unique opportunity of witnessing the birth and evolution of a supernova remnant. Monitoring the source in X-rays provides insights into the physics of the shock, the X-ray emitting plasma, and the interaction of the shock with the structures in the circumstellar medium. The source has been monitored by XMM-Newton EPIC-pn from 2007 to 2020. SRG/eROSITA also observed the source during its commissioning phase and first light in September and October 2019. Aims. We investigated the spectral and flux evolution of SN 1987A in X-rays in the last 14 yr up to November 2020 using XMM-Newton and eROSITA observations. Methods. We performed a detailed spectral analysis using a three-component plane-parallel shock model and analysed and modelled the EPIC-pn monitoring and eROSITA observations in a consistent manner. Results. This paper reports a complete and the most recent flux evolution of SN 1987A in the soft (0.5−2 keV) and hard (3−10 keV) X-ray band. The flux in the soft band flattened around 9424 days and then displayed a turnover between 10 142 and 10 493 days, after which it showed a continued decline. At about the same time, a break in the hard-band flux time evolution slope was detected. This implies that the blast wave has now passed beyond the dense structures of the equatorial ring and is expanding farther into more tenuous circumstellar medium. The temporal evolution of the normalisations of the three shock components match the results of hydrodynamical simulations well, which predict a blue supergiant progenitor scenario. The trend in recent epochs indicates that the emission caused by the forward shock after leaving the equatorial ring and by the reverse shock in the ejecta is now becoming more dominant. The elemental abundances in the hot plasma component are significantly higher than those in the cooler component, indicating an origin in the reverse shock that propagates into the ejecta.

The eROSITA view of the Abell 3391/95 field: The Northern Clump

Context.Galaxy clusters grow through mergers and the accretion of substructures along large-scale filaments. Many of the missing baryons in the local Universe may reside in such filaments as the warm-hot intergalactic medium (WHIM).Aims.SRG/eROSITA performance verification observations revealed that the binary cluster Abell 3391/3395 and the Northern Clump (the MCXC J0621.7–5242 galaxy cluster) are aligning along a cosmic filament in soft X-rays, similarly to what has been seen in simulations before. We aim to understand the dynamical state of the Northern Clump as it enters the atmosphere (3 ×R200) of Abell 3391.Methods.We analyzed joint eROSITA,XMM-Newton, andChandraobservations to probe the morphological, thermal, and chemical properties of the Northern Clump from its center out to a radius of 988 kpc (R200). We utilized the ASKAP/EMU radio data, the DECam optical image, and thePlanck y-map to study the influence of the wide-angle tail (WAT) radio source on the Northern Clump’s central intracluster medium. Using eROSITA data, we also analyzed the gas properties of the Northern Filament, the region between the virial radii of the Northern Clump and the A3391 cluster. From the Magneticum simulation, we identified an analog of the A3391/95 system along with an infalling group resembling the Northern Clump.Results.The Northern Clump is a weak cool-core cluster centered on a WAT radio galaxy. The gas temperature over 0.2–0.5R500iskBT500=1.99 ± 0.04 keV. We employed the mass-temperature(M – T) scaling relation and obtained a mass estimate ofM500= (7.68 ± 0.43) × 1013M⊙andR500= (63 6 ± 12) kpc. Its X-ray atmosphere has a boxy shape and deviates from spherical symmetry. We identify a southern surface brightness edge, likely caused by subsonic motion relative to the filament gas in the southern direction. At ~R500, the southern atmosphere (infalling head) appears to be 42% hotter than its northern atmosphere. We detect a downstream tail pointing toward the north with a projected length of ~318 kpc, plausibly the result of ram pressure stripping. Through a two-temperature fit, we identify a cooler component in the Northern Filament withkBT= 0.68- 0.64+ 0.38keV andne= 1.99-1.24+0.88× 10-5cm-3, which are consistent within the expected ranges of WHIM properties. The analog group in the Magneticum simulation is experiencing changes in its gas properties and a shift between the position of the halo center and that of the bound gas, while approaching the main cluster pair.Conclusions.The Northern Clump is a dynamically active system and far from being relaxed. Its atmosphere is affected by an interaction with the WAT and by gas sloshing or its infall toward Abell 3391 along the filament, consistent with the analog group-size halo in the Magneticum simulation.

Broadband X-ray spectral variability of the pulsing ULX NGC 1313 X-2

Context. It is thought that ultraluminous X-ray sources (ULXs) are mainly powered by super-Eddington accreting neutron stars or black holes as shown by the recent discovery of X-ray pulsations and relativistic winds. Aims. This work presents a follow-up study of the spectral evolution over two decades of the pulsing ULX NGC 1313 X-2 in order to understand the structure of the accretion disc. The primary objective is to determine the shape and nature of the dominant spectral components by investigating their variability with the changes in the source luminosity. Methods. We performed a spectral analysis over the canonical 0.3–10.0 keV energy band of all the high signal-to-noise XMM-Newton observations (96% of the available data), and we tested a number of different spectral models, which should approximate super-Eddington accretion discs. The baseline model consists of two thermal blackbody components with different temperatures plus an exponential cutoff powerlaw. Results. The baseline model provides a good description of the X-ray spectra. In particular, the hotter and brighter (LX ∼ 6–9 × 1039 erg s−1) thermal component describes the emission from the super-Eddington inner disc and the cutoff powerlaw describes the contribution from the accretion column of the neutron star. Instead, the cooler component describes the emission from the outer region of the disc close to the spherisation radius and the wind. The luminosity-temperature relation for the cool component follows a negative trend, which is not consistent with L ∝ T4, as is expected from a sub-Eddington thin disc of Shakura-Sunayev. This is not consistent with L ∝ T2 either, as is expected for an advection-dominated disc. However, this would rather agree with a wind-dominated X-ray emitting region. Instead, the (Lx, Tdisk) relation for the hotter component is somewhere in between the first two theoretical scenarios. Conclusions. Our findings agree with the super-Eddington scenario and provide further detail on the disc structure. The source spectral evolution is qualitatively similar to that seen in NGC 1313 X-1 and Holmberg IX X-1, indicating a common structure and evolution among archetypal ULXs.

Machine vision problem for fast recognition of surface defects of thermoelectric cooler components based on deep learning method

During thermoelectric coolers (TEC) production, a complex industrial manufacturing process must be experienced, which may cause defects on the surface of the TEC component. To improve the efficiency of TEC component defect inspection, we propose a machine vision technology based on deep learning for surface defect detection. In order to make the deep learning method based on the you only look once (YOLO) model more efficient, first of all, we use a more lightweight network ResNet34 to improve the original network structure. Then, the loss function is improved to complete intersection over union (CIoU) loss. Experiments performed using the proposed model, show an obvious reduction in the number of parameters, the detection speed is as high as 6.5pcs/s, and the detection accuracy is 97.61%. This method lay a good foundation for the further application of deep learning methods in the field of industrial detection. The experimental results verify the feasibility and effectiveness of the model.

Feature extraction based on Gabor filter and Support Vector Machine classifier in defect analysis of Thermoelectric Cooler Component

PurposeDuring the slicing process, thermoelectric cooler (TEC) component are prone to cause various defects, such as cracks, pockmarks, and other defects of various shapes and sizes. The presence of these surface defects will lead to a decline in product performance. At present, the method of screening TEC component is mainly manual detection. This method is affected by the strong subjectivity of human beings and the limited spatial resolution. Therefore, a method based on machine learning is proposed to overcome the above shortcomings and obtain product accuracy that is difficult for artificial vision to achieve MethodWe use Gabor filters to extract texture information in the TEC component image and use it as a classification feature. At the same time, principal component analysis (PCA) is used to select the classification features. For the number of defect types, we use support vector machine (SVM) to classify unknown defects. By extracting the features of the TEC component image and using it for SVM training. Finally, the unknown defect image is used as input to obtain the defect category ResultsBy testing the TEC simultaneously with other machine learning methods in this paper, the superiority of this method is proved. At the same time, it also overcomes a series of problems such as slow manual detection speed, low reliability, poor consistency and stability of test results, product quality cannot be improved, and low detection efficiency ConclusionBased on our experimental analysis, the proposed method can effectively improve the classification effect of TEC component defects. Compared with other classifiers, the effectiveness of this method is further verified.

Rapid mass transfer between the twin components in the hierarchical triple system GK Cep

ABSTRACT GK Cep is an eclipsing binary that contains two A-type components with an orbital period of 0.936 d. The high mass ratio and the contact or near-contact configuration make it a key target to understand binary evolution. However, the physical properties and evolutionary state are still unknown. Here we present the UV light curve obtained by using the lunar-based ultraviolet telescope (LUT) and several eclipse times obtained with the Sino-Thai 70-cm telescope and the 1.0-m telescope at Yunnan Observatories. Analysis of the LUT light curve suggests that GK Cep is a near-contact semidetached system where the slightly less massive component is the hotter one that is filling the critical Roche lobe. Meanwhile, a hotspot is found on the neck of the more massive but cooler component. By using all available times for the light minimum, it is detected that the O–C curve shows a cyclic oscillation while it undergoes an upward parabolic change. The increase of the orbital period, the high mass ratio, the semidetached configuration with a lobe-filling less massive component, and the presence of a hotspot on the more massive component all suggest that GK Cep is in a key evolutionary state just after the shortest-period evolutionary stage during the rapid mass transfer. The cyclic change in the O–C curve reveals that GK Cep contains a solar-type stellar companion in a triply hierarchical system that is in agreement with the spectroscopic result. The third body contributes about 2.6 per cent to the total light of the triple system.

High Resolution Soft X-ray Spectroscopy and the Quest for the Hot (5–10 MK) Plasma in Solar Active Regions

We discuss the diagnostics available to study the 5–10 MK plasma in the solar corona, which is key to understanding the heating in the cores of solar active regions. We present several simulated spectra, and show that excellent diagnostics are available in the soft X-rays, around 100 Å, as six ionization stages of Fe can simultaneously be observed, and electron densities derived, within a narrow spectral region. As this spectral range is almost unexplored, we present an analysis of available and simulated spectra, to compare the hot emission with the cooler component. We adopt recently designed multilayers to present estimates of count rates in the hot lines, with a baseline spectrometer design. Excellent count rates are found, opening up the exciting opportunity to obtain high-resolution spectroscopy of hot plasma.

NEW SPECTRAL ANALYSIS RESULTS WITHIN THE SCOPE OF EXTENDED MATTER RESEARCH IN THE AR LACERTAE ACTIVE BINARY SYSTEM

Within the scope of extended matter research, we present new spectral analysis results of an active binary system, AR Lac. The low and high resolution spectra of this system, were taken during the period 2013-2016. The evaluation of low dispersion spectra together with the B, V, Rc, Ic and WISE photometric data showed that AR Lac has an excess radiation in the W2 band. In addition, the spectral energy distribution and the minima depth ratios of the light curves of this active binary system were studied to examine the flux contributions of the components of the system depending on wavelengths and on orbital phase. Furthermore, high resolution spectral analysis showed evidence of prominence-like structures and a possible extended matter around the cooler component of AR Lac.

Probing the Hot Circumgalactic Medium with Broad O vi and X-Rays

Abstract Most of the baryonic mass in the circumgalactic medium (CGM) of a spiral galaxy is believed to be warm-hot, with temperature around 106 K. The narrow O vi absorption lines probe a somewhat cooler component at , but broad O vi absorbers have the potential to probe the hotter CGM. Here we present 376 ks Chandra LETG observations of a carefully selected galaxy in which the presence of broad O vi together with the non-detection of Lyα was indicative of hot gas. The strongest line expected to be present at ≈106 K is O vii λ21.602. There is a hint of an absorption line at the redshifted wavelength, but the line is not detected with better than 2σ significance. A physical model, taking into account strengths of several other lines, provides better constraints. Our best-fit absorber model has and . These parameters are consistent with the hot plasma model based on UV observations; other O vi models of cooler gas phases are ruled out at better than 99% confidence. Thus we have suggestive, but not conclusive evidence for the broad O vi absorber probing the hot gas from the shallow observations of this pilot program. About 800 ks of XMM-Newton observations will detect the expected absorption lines of O vii and O viii unequivocally. Future missions like XRISM, Arcus, and Athena will revolutionize the CGM science.