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<jats:title>Abstract</jats:title> <jats:p>There are only a few very-high-energy sources in our Galaxy that might accelerate particles up to the knee of the cosmic-ray spectrum. To understand the mechanisms of particle acceleration in these PeVatron candidates, Fermi-Large Area Telescope (LAT) and High-Energy Stereoscopic System (H.E.S.S.) observations are essential to characterize their <jats:italic>γ</jats:italic>-ray emission. HESS J1640–465 and the PeVatron candidate HESS J1641–463 are two neighboring (0.25°) <jats:italic>γ</jats:italic>-ray sources, spatially coincident with the radio supernova remnants (SNRs) G338.3–0.0 and G338.5+0.1. Detected both by H.E.S.S. and the Fermi-LAT, we present here a morphological and spectral analysis of these two sources using 8 yr of Fermi-LAT data between 200 MeV and 1 TeV with multiwavelength observations to assess their nature. The morphology of HESS J1640–465 is described by a 2D Gaussian (<jats:italic>σ</jats:italic> = 0.053° ± 0.011°<jats:sub>stat</jats:sub> ± 0.03°<jats:sub>syst</jats:sub>) and its spectrum is modeled by a power law with a spectral index Γ = 1.8 ± 0.1<jats:sub>stat</jats:sub> ± 0.2<jats:sub>syst</jats:sub>. HESS J1641–463 is detected as a point-like source and its GeV emission is described by a logarithmic-parabola spectrum with <jats:italic>α</jats:italic> = 2.7 ± 0.1<jats:sub>stat</jats:sub> ± 0.2<jats:sub>syst</jats:sub> and significant curvature of <jats:italic>β</jats:italic> = 0.11 ± 0.03<jats:sub>stat</jats:sub> ± 0.05<jats:sub>syst</jats:sub>. Radio and X-ray flux upper limits were derived. We investigated scenarios to explain their emission, namely, the emission from accelerated particles within the SNRs spatially coincident with each source, molecular clouds illuminated by cosmic rays from the close-by SNRs, and a pulsar/pulsar wind nebula origin. Our new Fermi-LAT results and the radio and flux X-ray upper limits pose severe constraints on some of these models.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Theoretical and numerical works indicate that a strong magnetic field should suppress fragmentation in dense cores. However, this has never been tested observationally in a relatively large sample of fragmenting massive dense cores. Here, we use the polarization data obtained in the Submillimeter Array Legacy Survey of Zhang et al. to build a sample of 18 massive dense cores where both fragmentation and magnetic field properties are studied in a uniform way. We measured the fragmentation level, <jats:italic>N</jats:italic> <jats:sub>mm</jats:sub>, within the field of view common to all regions of ∼0.15 pc, with a mass sensitivity of ∼0.5 <jats:italic>M</jats:italic> <jats:sub>☉</jats:sub>, and a spatial resolution of ∼1000 au. In order to obtain the magnetic field strength using the Davis–Chandrasekhar–Fermi method, we estimated the dispersion of the polarization position angles, the velocity dispersion of the H<jats:sup>13</jats:sup>CO<jats:sup>+</jats:sup>(4–3) gas, and the density of each core, all averaged within 0.15 pc. A strong correlation is found between <jats:italic>N</jats:italic> <jats:sub>mm</jats:sub> and the average density of the parental core, although with significant scatter. When large-scale systematic motions are separated from the velocity dispersion and only the small-scale (turbulent) contribution is taken into account, a tentative correlation is found between <jats:italic>N</jats:italic> <jats:sub>mm</jats:sub> and the mass-to-flux ratio, as suggested by numerical and theoretical works.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present Tully–Fisher distances for 24 active galactic nucleus (AGN) host galaxies with black hole mass (<jats:italic>M</jats:italic> <jats:sub> <jats:sc>BH</jats:sc> </jats:sub>) measurements from reverberation mapping, as well as the first calibration of the <jats:italic>V</jats:italic>-band Tully–Fisher relation. Combining our measurements of H <jats:sc>i</jats:sc> 21 cm emission with Hubble Space Telescope and ground-based optical and near-infrared images allows multiple distance measurements for 19 galaxies and single measurements for the remaining 5. Separation of the nucleus from its host galaxy via surface brightness decomposition yields galaxy-only luminosities, thus allowing measurements of the distance moduli free of contamination from the AGNs. For 14 AGN hosts, these are the first reported distances independent of redshift, and hence independent of peculiar velocities. For the remaining galaxies, we show good agreement between our distances and those previously reported from surface brightness fluctuations and Cepheids. We also determine the total galaxy mass enclosed within the estimated H <jats:sc>i</jats:sc> radius, which when compared to the baryonic content allows for constraints on the dark matter masses. We find a typical mass fraction of <jats:italic>M</jats:italic> <jats:sub> <jats:sc>DM</jats:sc> </jats:sub>/<jats:italic>M</jats:italic> <jats:sub> <jats:sc>DYN</jats:sc> </jats:sub> = 62%, and find significant correlations between <jats:italic>M</jats:italic> <jats:sub> <jats:sc>BH</jats:sc> </jats:sub>–<jats:italic>M</jats:italic> <jats:sub> <jats:sc>DYN</jats:sc> </jats:sub> and <jats:italic>M</jats:italic> <jats:sub> <jats:sc>BH</jats:sc> </jats:sub>–<jats:italic>M</jats:italic> <jats:sub> <jats:sc>DM</jats:sc> </jats:sub>. Finally, we scale our galaxy radii based on estimated relationships between visible and halo radii and assume a flat rotation curve out to the halo radius to approximate <jats:italic>M</jats:italic> <jats:sub> <jats:sc>HALO</jats:sc> </jats:sub>. Over the range of <jats:italic>M</jats:italic> <jats:sub> <jats:sc>BH</jats:sc> </jats:sub> and <jats:italic>M</jats:italic> <jats:sub> <jats:sc>HALO</jats:sc> </jats:sub> in this sample, we find good agreement with observationally constrained relationships between <jats:italic>M</jats:italic> <jats:sub> <jats:sc>BH</jats:sc> </jats:sub> and <jats:italic>M</jats:italic> <jats:sub> <jats:sc>HALO</jats:sc> </jats:sub> and with hydrodynamical simulations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We describe a complete, flux-density-limited sample of galaxies at redshift 0.8 &lt; <jats:italic>z</jats:italic> &lt; 1.3 selected at 16 <jats:italic>μ</jats:italic>m. At the selection wavelength near 8 <jats:italic>μ</jats:italic>m rest, the observed emission comes from both dust heated by intense star formation and active galactic nuclei (AGNs). Fitting the spectral energy distributions (SEDs) of the sample galaxies to local-galaxy templates reveals that more than half the galaxies have SEDs dominated by star formation. About one-sixth of the galaxy SEDs are dominated by an AGN, and nearly all of the rest of the SEDs are composite. Comparison with X-ray and far-infrared observations shows that combinations of luminosities at rest-frame 4.5 and 8 <jats:italic>μ</jats:italic>m give good measures of both AGN luminosity and star formation rate. The sample galaxies mostly follow the established star-forming main sequence for <jats:italic>z</jats:italic> = 1 galaxies, but of the galaxies more than 0.5 dex above that main sequence, more than half have AGN-type SEDs. Similarly, the most luminous AGNs tend to have higher star formation rates than the main-sequence value. Galaxies with stellar masses &gt;10<jats:sup>11</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> are unlikely to host an AGN. About 1% of the sample galaxies show an SED with dust emission typical of neither star formation nor an AGN.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We analyze the 3D morphology and kinematics of 13 open clusters (OCs) located within 500 pc of the Sun, using Gaia EDR 3 and kinematic data from the literature. Members of OCs are identified using the unsupervised machine-learning method <jats:sc>StarGO,</jats:sc> using five parameters (<jats:italic>X</jats:italic>, <jats:italic>Y</jats:italic>, <jats:italic>Z</jats:italic>, <jats:inline-formula> <jats:tex-math> <?CDATA ${\mu }_{\alpha }\cos \delta ,{\mu }_{\delta }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabeaacieqn1.gif" xlink:type="simple" /> </jats:inline-formula>). The OC sample covers an age range of 25 Myr to 2.65 Gyr. We correct the asymmetric distance distribution that is due to parallax error using Bayesian inversion. The uncertainty in the corrected distance for a cluster at 500 pc is 3.0–6.3 pc, depending on the intrinsic spatial distribution of its members. We determine the 3D morphology of the OCs in our sample and fit the spatial distribution of stars within the tidal radius in each cluster with an ellipsoid model. The shapes of the OCs are well described with oblate spheroids (NGC 2547, NGC 2516, NGC 2451A, NGC 2451B, and NGC 2232), prolate spheroids (IC 2602, IC 4665, NGC 2422, Blanco 1, and Coma Berenices), or triaxial ellipsoids (IC 2391, NGC 6633, and NGC 6774). The semimajor axis of the fitted ellipsoid is parallel to the Galactic plane for most clusters. Elongated filament-like substructures are detected in three young clusters (NGC 2232, NGC 2547, and NGC 2451B), while tidal-tail-like substructures (tidal tails) are found in older clusters (NGC 2516, NGC 6633, NGC 6774, Blanco 1, and Coma Berenices). Most clusters may be supervirial and expanding. <jats:italic>N</jats:italic>-body models of rapid gas expulsion with a star formation efficiency of ≈1/3 are consistent with clusters more massive than 250 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, while clusters less massive than 250 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> tend to agree with adiabatic gas expulsion models. Only five OCs (NGC 2422, NGC 6633, NGC 6774, Blanco 1, and Coma Berenices) show clear signs of mass segregation.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The elemental and isotopic compositions of meteorites are expected to reflect several key processes that occurred in the early solar system, including the migration of gas and dust throughout the protoplanetary disk, the formation of chondrules, and the accretion of the first planetary bodies. However, the specific origins of the various compositions measured among these rocks are currently poorly constrained, limiting our understanding of these processes. Here, we use previously measured elemental and isotopic compositions of chondrites and iron meteorites to identify that carbonaceous (CC) meteorites are mixtures of noncarbonaceous (NC) material, calcium–aluminum-rich inclusion (CAI) material, and CI (Ivuna-like) material, in varying proportions. These trends indicate that chondrules in CO (Ornans-like), CM (Mighei-like), CV (Vigarano-like), and TL (Tagish Lake) chondrites share near-identical average proportions of CI material, arguing that they were generated through the remelting of preexisting NC chondrules all in the same disk environment. Because this proportion likely evolved over space and time throughout the disk, this similarity argues that these chondrules originate from a restricted spatial region and time interval, favoring their generation through a localized event. Moreover, the compositions of CR (Renazzo-like) chondrites indicate that their constituents formed through mechanisms different from those in CO, CM, CV, and TL chondrites. The recovered proportions of CI material in CC iron meteorites and chondrites together also argue for evolution in either the predominant direction of dust and gas motion in the first ∼10 au of the disk or the radial distance of planetesimal accretion throughout the CC reservoir.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We aim at estimating the dust scale height of protoplanetary disks from millimeter continuum observations. First, we present a general expression of intensity of a ring in a protoplanetary disk and show that we can constrain the dust scale height by the azimuthal intensity variation. Then, we apply the presented methodology to the two distinct rings at 68 au and at 100 au of the protoplanetary disk around HD 163296. We constrain the dust scale height by comparing the high-resolution millimeter dust continuum image obtained in the Disk Substructures at High Angular Resolution Project (DSHARP) with radiative transfer simulations using RADMC-3D. We find that <jats:italic>h</jats:italic> <jats:sub>d</jats:sub>/<jats:italic>h</jats:italic> <jats:sub>g</jats:sub> &gt; 0.84 at the inner ring and <jats:italic>h</jats:italic> <jats:sub>d</jats:sub>/<jats:italic>h</jats:italic> <jats:sub>g</jats:sub> &lt; 0.11 at the outer ring with 3<jats:italic>σ</jats:italic> uncertainties, where <jats:italic>h</jats:italic> <jats:sub>d</jats:sub> is the dust scale height and <jats:italic>h</jats:italic> <jats:sub>g</jats:sub> is the gas scale height. This indicates that the dust is flared at the inner ring and settled at the outer ring. We further constrain the ratio of the turbulence parameter <jats:italic>α</jats:italic> to the gas-to-dust-coupling parameter St from the derived dust scale height; <jats:italic>α</jats:italic>/St &gt; 2.4 at the inner ring, and <jats:italic>α</jats:italic>/St &lt; <jats:inline-formula> <jats:tex-math> <?CDATA $1.1\times {10}^{-2}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>1.1</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabe5a6ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> at the outer ring. This result shows that the turbulence is stronger or the dust is smaller at the inner ring than at the outer ring.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We have carried out a search for massive white dwarfs (WDs) in the direction of young open star clusters using the Gaia DR2 database. The aim of this survey was (1) to provide robust data for new and previously known high-mass WDs regarding cluster membership, (2) to highlight WDs previously included in the initial final mass relation (IFMR) that are unlikely members of their respective clusters according to Gaia astrometry, and (3) to select an unequivocal WD sample that could then be compared with the host clusters’ turnoff masses. All promising WD candidates in each cluster color–magnitude diagram were followed up with spectroscopy from Gemini in order to determine whether they were indeed WDs and derive their masses, temperatures, and ages. In order to be considered cluster members, white dwarfs were required to (1) have proper motions and parallaxes within 2<jats:italic>σ</jats:italic>, 3<jats:italic>σ</jats:italic>, or 4<jats:italic>σ</jats:italic> of those of their potential parent cluster based on how contaminated the field was in their region of the sky, (2) have a cooling age that was less than the cluster age, and (3) have a mass that was broadly consistent with the IFMR. A number of WDs included in current versions of the IFMR turned out to be nonmembers, and a number of apparent members, based on Gaia’s astrometric data alone, were rejected, as their mass and/or cooling times were incompatible with cluster membership. In this way, we developed a highly selected IFMR sample for high-mass WDs that, surprisingly, contained no precursor masses significantly in excess of ∼ 6 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>.</jats:p>