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<jats:title>Abstract</jats:title> <jats:p>This paper provides the set of Rankine–Hugoniot (R–H) jump conditions for shocks in space and astrophysical plasmas described by kappa, distributions. The characteristic result is the development of a new R–H condition that transforms the values of kappa upstream and downstream the shock. The kappa index parameterizes and labels kappa distributions, and it is necessary for characterizing the thermodynamics of space plasmas. This first approach is restricted to non-magnetized plasmas, and the whole achievement is derived by following first principles of statistical mechanics and thermodynamics. The results show that, depending on the shock strength, the kappa indices across the shock may decrease or increase, indicating cases of shock acceleration or deceleration, respectively.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The initial physical conditions of high-mass stars and protoclusters remain poorly characterized. To this end, we present the first targeted ALMA Band 6 1.3 mm continuum and spectral line survey toward high-mass starless clump candidates, selecting a sample of 12 of the most massive candidates (<jats:inline-formula> <jats:tex-math> <?CDATA $4\times {10}^{2}\,{M}_{\odot }\lesssim {M}_{\mathrm{cl}}\lesssim 4\times {10}^{3}\,{M}_{\odot }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn1.gif" xlink:type="simple" /> </jats:inline-formula>) within <jats:inline-formula> <jats:tex-math> <?CDATA ${d}_{\odot }\lt 5\,\mathrm{kpc}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn2.gif" xlink:type="simple" /> </jats:inline-formula>. The joint <jats:inline-formula> <jats:tex-math> <?CDATA $12+7\,{\rm{m}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn3.gif" xlink:type="simple" /> </jats:inline-formula> array maps have a high spatial resolution of <jats:inline-formula> <jats:tex-math> <?CDATA $\lesssim 3000\,\mathrm{au}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn4.gif" xlink:type="simple" /> </jats:inline-formula> (<jats:inline-formula> <jats:tex-math> <?CDATA $0.015\,\mathrm{pc}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn5.gif" xlink:type="simple" /> </jats:inline-formula>, <jats:italic>θ</jats:italic> <jats:sub>syn</jats:sub> ≈ 0.″8) and have high point-source mass-completeness down to <jats:inline-formula> <jats:tex-math> <?CDATA $M\approx 0.3\,{M}_{\odot }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn6.gif" xlink:type="simple" /> </jats:inline-formula> at <jats:inline-formula> <jats:tex-math> <?CDATA $6{\sigma }_{\mathrm{rms}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn7.gif" xlink:type="simple" /> </jats:inline-formula> (or <jats:inline-formula> <jats:tex-math> <?CDATA $1{\sigma }_{\mathrm{rms}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn8.gif" xlink:type="simple" /> </jats:inline-formula> column density sensitivity of <jats:inline-formula> <jats:tex-math> <?CDATA $N=1.1\times {10}^{22}\,{\mathrm{cm}}^{-2}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn9.gif" xlink:type="simple" /> </jats:inline-formula>). We discover previously undetected signposts of low-luminosity star formation from <jats:inline-formula> <jats:tex-math> <?CDATA $\mathrm{CO}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn10.gif" xlink:type="simple" /> </jats:inline-formula> <jats:inline-formula> <jats:tex-math> <?CDATA $J=2\to 1$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn11.gif" xlink:type="simple" /> </jats:inline-formula> and <jats:inline-formula> <jats:tex-math> <?CDATA $\mathrm{SiO}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn12.gif" xlink:type="simple" /> </jats:inline-formula> <jats:inline-formula> <jats:tex-math> <?CDATA $J=5\to 4$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn13.gif" xlink:type="simple" /> </jats:inline-formula> bipolar outflows and other signatures toward 11 out of 12 clumps, showing that current MIR/FIR Galactic plane surveys are incomplete to low- and intermediate-mass protostars (<jats:inline-formula> <jats:tex-math> <?CDATA ${L}_{\mathrm{bol}}\lesssim 50\,{L}_{\odot }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn14.gif" xlink:type="simple" /> </jats:inline-formula>), and emphasizing the necessity of high-resolution follow-up. We compare a subset of the observed cores with a suite of radiative transfer models of starless cores. We find a high-mass starless core candidate with a model-derived mass consistent with <jats:inline-formula> <jats:tex-math> <?CDATA ${29}_{15}^{52}\,{M}_{\odot }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn15.gif" xlink:type="simple" /> </jats:inline-formula> when integrated over size scales of <jats:inline-formula> <jats:tex-math> <?CDATA $R\lt 2\times {10}^{4}\,\mathrm{au}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn16.gif" xlink:type="simple" /> </jats:inline-formula>. Unresolved cores are poorly fit by radiative transfer models of externally heated Plummer density profiles, supporting the interpretation that they are protostellar even without detection of outflows. A high degree of fragmentation with rich substructure is observed toward 10 out of 12 clumps. We extract sources from the maps using a dendrogram to study the characteristic fragmentation length scale. Nearest neighbor separations, when corrected for projection with Monte Carlo random sampling, are consistent with being equal to the clump average thermal Jeans length (<jats:inline-formula> <jats:tex-math> <?CDATA ${\lambda }_{{\rm{j}},\mathrm{th}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn17.gif" xlink:type="simple" /> </jats:inline-formula>; i.e., separations equal to <jats:inline-formula> <jats:tex-math> <?CDATA $0.4\mbox{--}1.6\times {\lambda }_{{\rm{j}},\mathrm{th}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn18.gif" xlink:type="simple" /> </jats:inline-formula>). In the context of previous observations that, on larger scales, see separations consistent with the turbulent Jeans length or the cylindrical thermal Jeans scale (<jats:inline-formula> <jats:tex-math> <?CDATA $\approx 3\mbox{--}4\times {\lambda }_{{\rm{j}},\mathrm{th}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab40caieqn19.gif" xlink:type="simple" /> </jats:inline-formula>), our findings support a hierarchical fragmentation process, where the highest-density regions are not strongly supported against thermal gravitational fragmentation by turbulence or magnetic fields.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>State of the art spectral retrieval models of exoplanet atmospheres assume constant chemical profiles with altitude. This assumption is justified by the information content of current data sets which do not allow, in most cases, for the molecular abundances as a function of pressure to be constrained. In the context of the next generation of telescopes, a more accurate description of chemical profiles may become crucial to interpret observations and gain new insights into atmospheric physics. We explore here the possibility of retrieving pressure-dependent chemical profiles from transit spectra, without injecting any priors from theoretical chemical models in our retrievals. The “two-layer” parameterization presented here allows for the independent extraction of molecular abundances above and below a certain atmospheric pressure. By simulating various cases, we demonstrate that this evolution from constant chemical abundances is justified by the information content of spectra provided by future space instruments. Comparisons with traditional retrieval models show that assumptions made on chemical profiles may significantly impact retrieved parameters, such as the atmospheric temperature, and justify the attention we give here to this issue. We find that the two-layer retrieval accurately captures discontinuities in the vertical chemical profiles, which could be caused by disequilibrium processes—such as photochemistry—or the presence of clouds/hazes. The two-layer retrieval could also help to constrain the composition of clouds and hazes by exploring the correlation between the chemical changes in the gaseous phase and the pressure at which the condensed phase occurs. The two-layer retrieval presented here therefore represents an important step forward in our ability to constrain theoretical chemical models and cloud/haze composition from the analysis of future observations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We describe the interface between the outer heliosphere and the local interstellar medium (LISM) surrounding the Sun. The components of the inner LISM are the four partially ionized clouds (the Local Interstellar Cloud (LIC), G cloud, Blue cloud, and Aql cloud) that are in contact with the outer heliosphere, and ionized gas produced by EUV radiation primarily from <jats:italic>ϵ</jats:italic> CMa. We construct the three-dimensional shape of the LIC based on interstellar line absorption along 62 sightlines and show that in the directions of <jats:italic>ϵ</jats:italic> CMa, <jats:italic>β</jats:italic> CMa, and Sirius B the neutral hydrogen column density from the center of the LIC is a minimum. We call this region the “hydrogen hole.” In this direction, the presence of Blue cloud absorption and the absence of LIC absorption can be simply explained by the Blue cloud lying just outside the heliosphere. We propose that the outer edge of the Blue cloud is a Strömgren shell driven toward the heliosphere by high pressures in the H <jats:sc>ii</jats:sc> region. We find that the vectors of neutral and ionized helium flowing through the heliosphere are inconsistent with the LIC flow vector, and that the nearby intercloud gas is consistent with ionization by <jats:italic>ϵ</jats:italic> CMa and other stellar sources without requiring additional sources of ionization or million-degree plasma. In the upwind direction, the heliosphere is passing through an environment of several LISM clouds, which may explain the recent influx of interstellar grains containing <jats:sup>60</jats:sup>Fe from supernova ejecta measured in Antarctic snow.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The radius–luminosity (<jats:inline-formula> <jats:tex-math> <?CDATA ${R}_{{\rm{H}}\beta }\mbox{--}{L}_{5100}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab4908ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>) relationship of active galactic nuclei (AGNs) established by the reverberation mapping (RM) observations has been widely used as a single-epoch black hole mass estimator in the research of large AGN samples. However, the recent RM campaigns discovered that the AGNs with high-accretion rates show shorter time lags by factors of a few comparing with the predictions from the <jats:inline-formula> <jats:tex-math> <?CDATA ${R}_{{\rm{H}}\beta }\mbox{--}{L}_{5100}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab4908ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> relationship. The explanation of the shortened time lags has not been finalized yet. We collect eight different single-epoch spectral properties to investigate how the shortening of the time lags correlates with those properties and to determine the origin of the shortened lags. We find that the flux ratio between Fe <jats:sc>ii</jats:sc> and H<jats:italic>β</jats:italic> emission lines shows the most prominent correlation, thus confirming that accretion rate is the main driver for the shortened lags. In addition, we establish a new scaling relation including the relative strength of Fe <jats:sc>ii</jats:sc> emission. This new scaling relation can provide less biased estimates of the black hole mass and accretion rate from the single-epoch spectra of AGNs.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In a previous work, Hoang and Tram discovered a new mechanism for destruction of nanoparticles due to suprathermal rotation of grains in stationary <jats:italic>C</jats:italic>-shocks, which is termed rotational disruption. In this paper, we extend our previous study for nonstationary shocks driven by outflows and young supernova remnants that have dynamical ages shorter than the time required to establish a stationary <jats:italic>C</jats:italic>-shock, which is composed of a <jats:italic>C</jats:italic>-shock and a <jats:italic>J</jats:italic>-shock tail (referred to as <jats:italic>CJ</jats:italic>-shock). For the <jats:italic>C</jats:italic>-shock component, we find that the smallest nanoparticles (size ≲1 nm) of weak materials (i.e., tensile strength <jats:italic>S</jats:italic> <jats:sub>max</jats:sub> ≲ 10<jats:sup>9</jats:sup> erg cm<jats:sup>−3</jats:sup>) can be rotationally disrupted owing to suprathermal rotation induced by supersonic neutral drift. For the <jats:italic>J</jats:italic>-shock component, although nanoparticles are rotating thermally, the smallest ones can still be disrupted because the gas is heated to higher temperatures by <jats:italic>J</jats:italic>-shocks. We then model microwave emission from rapidly spinning nanoparticles where the grain size distribution has the lower cutoff determined by rotational disruption for the different shock models. We also calculate the spectral flux of microwave emission from a shocked region at a distance of 100 pc from the observer for the different gas density, shock age, and shock velocities. We suggest that microwave emission from spinning dust can be used to trace nanoparticles and shock velocities in dense molecular outflows. Finally, we discuss a new way that can release molecules from the nanoparticle surface into the gas in the shocked regions, which we name rotational desorption.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Using global magnetohydrodynamic (MHD) simulations, we investigate the role played by a complex solar structure composed of a corotating interaction region (CIR) followed by solar wind Alfvénic fluctuations on the magnetosphere’s nightside, equatorial electric field oscillations in the ultra-low-frequency range. A series of numerical experiments are performed employing synthetic solar wind inputs resembling those of a real CIR+Alfvénic fluctuation event that reached Earth’s magnetosphere on 2003 April 20. The following is found: (i) Radial electric field component fluctuations are excited via magnetopause boundary motions driven either by solar wind density variations characteristic of CIRs or by solar wind Alfvénic fluctuations with a given oscillation period. (ii) Azimuthal electric field component fluctuations nearer to Earth, that is, at radial distances <jats:italic>R</jats:italic> less than about 5<jats:italic>R</jats:italic> <jats:sub>E</jats:sub> (<jats:inline-formula> <jats:tex-math> <?CDATA ${R}_{{\rm{E}}}=1$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab4db5ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> Earth radius), are apparently not related to either of the two types of sinusoidal solar wind Alfvénic fluctuations used in this study featuring monochromatic frequencies of 0.833 mHz (20-minute period) and 1.666 mHz (10-minute period). Instead, these innermost azimuthal component fluctuations show enhanced activity when inner magnetosphere convection increases as a result of a southward turning of the interplanetary magnetic field component <jats:italic>B</jats:italic> <jats:sub> <jats:italic>z</jats:italic> </jats:sub>. (iii) Lastly, outermost (<jats:italic>R</jats:italic> ≳ 7 <jats:italic>R</jats:italic> <jats:sub>E</jats:sub>) azimuthal electric field oscillations weakly respond to monochromatic solar wind Alfvénic fluctuations by showing power spectral density peaks at both driving frequencies, but only near the flanks of the magnetopause, thus suggesting that such oscillations are being excited also owing to magnetopause boundary motions driven by solar wind Alfvénic fluctuations.</jats:p>