NASA's Interstellar Boundary Explorer (IBEX) mission has operated in space for a full solar activity cycle (Solar Cycle 24), and IBEX observations have exposed the global three-dimensional structure ...of the heliosphere and its interaction with the very local interstellar medium for the first time. Here, we extend the prior IBEX observations of energetic neutral atoms (ENAs) by adding a comprehensive analysis of four additional years (2016 through 2019). We document several improvements and rerelease the entire 11 yr, IBEX-Hi data set. The new observations track the continuing expansion of the outer heliosphere's response to the large solar wind pressure increase in late 2014. We find that the intensification of ENAs from the heliosheath continued to expand progressively over time to directions farther from the initial, closest direction to the heliospheric boundaries, ∼20° south of the upwind direction. This expansion extended beyond the south pole in 2018 and the north pole in 2019, demonstrating that the termination shock and heliopause are closer in the south. The heliotail has not yet responded, indicating that the boundaries are significantly farther away in the downwind direction. Finally, the slow solar wind (∼1 keV) ENAs just started to intensify from the closest regions of the IBEX Ribbon. This is about two and a half years after the initial response from heliosheath ENAs and about four and a half years after the increase in solar wind output, both clearly implicating a "secondary ENA" source in the draped interstellar magnetic field, just beyond the heliopause.
The aim of the study was to examine physicochemical properties of three cationic surfactants and to evaluate the effectiveness of their removal with the use of polymeric membranes. The experiments ...were performed in a laboratory scale set-up with the use of Microdyn-Nadir
nanofiltration and ultrafiltration membranes. Cetrimonium bromide (CTAB), benzalkonium chloride (BAC) and Tequat LC90i (TEAQ) were chosen for the test. In the experiments, surfactant solutions in a wide range of concentration were treated (50-3,000 mg L
). The experimental research included evaluation of the effect of membrane type and solution parameters (surfactant type and concentration, presence of inorganic compounds) on the process efficiency (retention coefficient and permeate flux). It was shown that surfactant removal by means of the pressure-driven membrane processes is an extensive issue and its efficiency depends on many factors. Ultrafiltration and nanofiltration membranes proved to be usable in CTAB removal (separation exceeded 90%); however, the process effectiveness was affected by surfactant concentration, membrane polymer type and membrane pore size. Separation obtained for BAC was on the lower level - the use of nanofiltration membranes brought maximum retention of 70%. TEAQ separation was very high and reached 100% with the use of ultrafiltration membranes. Mineral salt addition led to significant drop in surfactant retention.
Abstract Direct observations of solar wind are mostly limited to the vicinity of the ecliptic plane. Retrieving the latitudinal structure of solar wind indirectly based on observations of the ...backscatter glow of interstellar neutral hydrogen is complex and requires support from theoretical models. The GLOWS instrument, to operate on the planned IMAP mission, will scan the helioglow along circumsolar rings with an angular distance of ∼75°. Its objective is to retrieve the latitudinal structure of the ionization rate of interstellar hydrogen and with this the structure of the solar wind. In preparation for the future analysis, we studied the sensitivity of the light curves to temporal and latitudinal variation of the ionization rate of interstellar hydrogen and the solar Ly α illumination. Based on carefully planned numerical experiments, we analyze the time delay and relaxation time of the system for variations of the ionization rate and solar illumination in heliolatitude and with time. We found that variations in the solar illumination are reflected in the helioglow without delay, but relaxation takes longer than the variation rise time. By contrast, variations in the ionization rate are anticorrelated with the helioglow brightness with a delay of several months. We also found that the helioglow is not sensitive to variations in the ionization rate at the solar poles, so retrieving the ionization rate and solar wind at the poles requires approximation of the ionization rate profiles with appropriate parametric functions.
We study the main astrophysical properties of differentially rotating neutron stars described as stationary and axisymmetric configurations of a moderately stiff Γ = 2 polytropic fluid. The high ...level of accuracy and of stability of our relativistic multidomain pseudo-spectral code enables us to explore the whole solution space for broad ranges of the degree of differential rotation, but also of the stellar density and oblateness. Staying within an astrophysically motivated range of rotation profiles, we investigate the characteristics of neutron stars with maximal mass for all types of families of differentially rotating relativistic objects identified in a previous article. We find that the maximum mass depends on both the degree of differential rotation and the type of solution. It turns out that the maximum allowed mass can be up to 4 times higher than what it is for nonrotating stars with the same equation of state. Such values are obtained for a modest degree of differential rotation but for one of the newly discovered types of solutions. Since such configurations of stars are not that extreme, this result may have important consequences for the gravitational wave signal expected from coalescing neutron star binaries or from some supernova events.
The composition of industrial wastewater, its purification and concentration processes using ceramic membrane modules were investigated. Industrial wastewater produced as a result of washing the ...production line at a plant manufacturing cationic surfactants (in the esterquats group) was subjected to membrane filtration in a semi-pilot plant, run in concentration mode. Analysis of the raw wastewater showed very high organic matter content, expressed as COD, in the range of 17,700 to 24,300 mg L−1 and the concentration of cationic surfactants amounted to 2890–3390 mg L−1 mg/L. Ceramic membrane modules with a pore size of 0.14 μm exhibited high effectiveness in surfactant wastewater treatment. COD, TOC and turbidity were reduced by 93%, 95%, and 99%, respectively. When the process was run in concentration mode almost 50% of the permeate was recovered.
Display omitted
Abstract
Interstellar neutral hydrogen flows into the heliosphere as a mixture of the primary and secondary populations from two somewhat different directions due to splitting occurring in the ...magnetized outer heliosheath. The direction of the inflow of interstellar neutral H observed in the inner heliosphere, confronted with that of the unperturbed flow of interstellar neutral helium, is important for understanding the geometry of the distortion of the heliosphere from axial symmetry. It is also needed for facilitating remote-sensing studies of the solar wind structure based on observations of the helioglow, such as those presently performed by SOHO/SWAN, and in the near future by IMAP/GLOWS. In the past, the only means to measure the direction of the flow of interstellar hydrogen were spectroscopic observations of the helioglow. Here, we propose a new method to determine this parameter based on a long series of photometric observations of the helioglow. The method is based on purely geometric considerations and does not depend on any model and absolute calibration of the measurements. We apply this method to sky maps of the helioglow available from the SOHO/SWAN experiment and derive the mean longitude of the flow of interstellar hydrogen. We obtain 253.°1 ± 2.°8, which is in perfect agreement with the previously obtained results based on spectroscopic observations.
Abstract Interstellar neutral (ISN) hydrogen is the most abundant species in the outer heliosheath and the very local interstellar medium (VLISM). Charge-exchange collisions in the outer heliosheath ...result in filtration, reducing the ISN hydrogen density inside the heliosphere. Additionally, these atoms are intensively ionized close to the Sun, resulting in a substantial reduction of their density within a few astronomical units from the Sun. The products of this ionization—pickup ions (PUIs)—are detected by charged particle detectors. The Solar Wind Around Pluto instrument on New Horizons provides, for the first time, PUI observations from the distant heliosphere. We analyze the observations collected between 22 and 52 au from the Sun to find the ISN hydrogen density profile and compare the results with predictions from global heliosphere models. We conclude that the density profile derived from the observations is inconsistent with steady-state model predictions. This discrepancy is not explained by time variations close to the Sun and thus may be related to the temporal evolution of the outer boundaries or VLISM conditions. Furthermore, we show that the cold and hot models of ISN hydrogen distribution are not a good approximation closer to the termination shock. Therefore, we recommend a new fiduciary point based on the available New Horizons observations at 40 au from the Sun, at ecliptic direction (285.°62, 1.°94), where the ISN hydrogen density is 0.11 cm −3 . The continued operation of New Horizons should give better insight into the source of the discussed discrepancy.
Context. Current star formation models imply that the binary fraction of Population III stars is non-zero. The evolution of these binaries must have led to the formation of compact object binaries. ...Aims. We estimate the gravitational wave background originating in these binaries and discuss its observability. Methods. The properties of the Population III binaries are investigated using a binary population synthesis code. We numerically model the background and take into account the evolution of eccentric binaries. Results. The gravitational wave background from Population III binaries dominates the spectrum below 100 Hz. If the binary fraction is larger than 10-2, the background will be detectable by Einstein Telescope (ET), Laser Interferometer Space Antenna (LISA), and DECi-Hertz Interferometer Gravitational wave Observatory (DECIGO). Conclusions. The gravitational wave background from Population III binaries will dominate the spectrum below 100 Hz. The instruments LISA, ET, and DECIGO should either see it easily or, in the case of non-detection, provide very strong constraints on the properties of the Population III stars.
Abstract
Interstellar neutral helium (ISN He) is an important source of information on the physical state of the local interstellar medium. Radiation pressure acting on the neutral helium atoms in ...the heliosphere has always been neglected; its effect has been considered insignificant compared to gravitational force. The most advanced numerical models of ISN He take into account more and more subtle effects; therefore, it is important to check if the effect of radiation pressure is still negligible. In this paper, we use the most up-to-date version of the Warsaw Test Particle Model (WTPM) to calculate the expected helium distribution in the heliosphere and simulate the flux of the ISN He observed by the Interstellar Boundary Explorer (IBEX) and in the future by the Interstellar Mapping and Acceleration Probe (IMAP). We compare results calculated with and without radiation pressure during low and high solar activity. The results show that in the analysis of IBEX-Lo observations, the radiation pressure acting on typical helium causes flux differences at a level of 1%–4% and is comparable to the observational errors. For the more sensitive IMAP-Lo instrument, there are some regions in the considered observation configurations where radiation pressure causes potentially statistically significant changes in the calculated fluxes. The effect can be up to 9% for the indirect beam and is likely to be higher than the estimated errors. Therefore, we claim that in the future analysis of the IMAP-Lo observations, radiation pressure acting on ISN He should be considered.
Context. The current gravitational wave detectors have reached their operational sensitivity and are nearing detection of compact object binaries. In the coming years, we expect that the Advanced ...LIGO/VIRGO will start taking data. At the same time, there are plans for third generation ground-based detectors such as the Einstein Telescope, and space detectors such as DECIGO. Aims. We discuss the eccentricity distribution of inspiral compact object binaries during they inspiral phase. We analyze the expected distributions of eccentricities at three frequencies that are characteristic of three future detectors: Advanced LIGO/VIRGO (30 Hz), Einstein Telescope (3 Hz), and DECIGO (0.3 Hz). Methods. We use the StarTrack binary population code to investigate the properties of the population of compact binaries in formation. We evolve their orbits until the point that they enter a given detector sensitivity window and analyze the eccentricity distribution at that time. Results. We find that the eccentricities of BH-BH and BH-NS binaries are quite small when entering the Advanced LIGO/VIRGO detector window for all considered models of binary evolution. Even in the case of the DECIGO detector, the typical eccentricities of BH-BH binaries are below 10-4, and the BH-NS eccentricities are smaller than 10-3. Some fraction of NS-NS binaries may have significant eccentricities. Within the range of considered models, we found that a fraction of between 0.2% and 2% NS-NS binaries will have an eccentricity above 0.01 for the Advanced LIGO/VIRGO detectors. For the ET detector, this fraction is between 0.4% and 4%, and for the DECIGO detector it lies between 2% and 27%.
PDF
