The RS Oph outburst of 2021 monitored in X-rays with NICER

The 2021 outburst of the symbiotic recurrent nova RS Oph was monitored with the Neutron Star Interior Composition Explorer Mission (NICER) in the 0.2-12 keV range from day one after the optical maximum, until day 88, producing an unprecedented, detailed view of the outburst development. The X-ray flux preceding the supersoft X-ray phase peaked almost 5 days after optical maximum and originated only in shocked ejecta for 21 to 25 days. The emission was thermal; in the first 5 days only a non-collisional-ionization equilibrium model fits the spectrum, and a transition to equilibrium occurred between days 6 and 12. The ratio of peak X-rays flux measured in the NICER range to that measured with Fermi in the 60 MeV-500 GeV range was about 0.1, and the ratio to the peak flux measured with H.E.S.S. in the 250 GeV-2.5 TeV range was about 100. The central supersoft X-ray source (SSS), namely the shell hydrogen burning white dwarf (WD), became visible in the fourth week, initially with short flares. A huge increase in flux occurred on day 41, but the SSS flux remained variable. A quasi-periodic oscillation every ~35 s was always observed during the SSS phase, with variations in amplitude and a period drift that appeared to decrease in the end. The SSS has characteristics of a WD of mass >1 M(solar). Thermonuclear burning switched off shortly after day 75, earlier than in 2006 outburst. We discuss implications for the nova physics.Comment: Accepted for publication in the Astrophysical Journa

The Influence of Outflow Feedback in Clumps

We analyzed the influence of outflow feedback from two perspectives: turbulent support and potential disruptive effect, of which 694 clumps and 188 have been identified as outflow candidates. For turbulent support, we find the slopes of E _turb − R _clump (turbulent energy and radius of the clump) and P _turb − R _clump (turbulent momentum and radius of the clump) have no difference and are consistent with expected values whether there is outflow feedback in clumps or not. The ratios of the outflow energy and momentum to the turbulence energy and momentum ( E _flow / E _turb , P _flow / P _turb ) show that the majority of clumps have not enough energy and momentum to support turbulence. Meanwhile, there is no correlation between the velocity dispersion and radius. For potential disruptive effects, we conclude that it is impossible for the outflow activities to disrupt entire clumps and as the mass of the clumps increases, the clumps becomes harder to destroy. Finally, we do not see evidence that the virial parameter changes significantly whether the clumps have outflow candidates or not

SILAR-Deposited CuS Electrocatalyst for High Power Polysulfide-based Aqueous Flow Battery

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E-blood: High power aqueous redox flow cell for concurrent powering and cooling of electronic devices

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A redox-mediated zinc electrode for ultra-robust deep-cycle redox flow batteries

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Redox-Mediated Ambient Electrolytic Nitrogen Reduction for Hydrazine and Ammonia Generation

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