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<jats:title>Abstract</jats:title> <jats:p>The discovery of the first two interstellar objects implies that, on average, every star contributes a substantial amount of material to the galactic population by ejecting such bodies from the host system. Because scattering is a chaotic process, a comparable amount of material should be injected into the inner regions of each system that ejects comets. For comets that are transported inwards and interact with planets, this Letter estimates the fraction of material that is accreted or outward-scattered as a function of planetary masses and orbital parameters. These calculations indicate that planets with escape velocities smaller than their current-day orbital velocities will efficiently accrete comets. We estimate the accretion efficiency for members of the current census of extrasolar planets and find that planetary populations including but not limited to hot and warm Jupiters, sub-Neptunes, and super-Earths can efficiently capture incoming comets. This cometary enrichment may have important ramifications for postformation atmospheric composition and chemistry. As a result, future detections and compositional measurements of interstellar comets will provide direct measurements of material that potentially enriched a subpopulation of the extrasolar planets. Finally, we estimate the efficiency of this enrichment mechanism for extrasolar planets that will be observed with the James Webb Space Telescope (JWST). With JWST currently operational and these observations imminently forthcoming, it is of critical importance to investigate how enrichment from interstellar comet analogs may affect the interpretations of exoplanet atmospheric compositions.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The heaviest elements in the universe are synthesized through rapid neutron capture (<jats:italic>r</jats:italic>-process) in extremely neutron-rich outflows. Neutron star mergers were established as an important <jats:italic>r</jats:italic>-process source through the multimessenger observation of GW170817. Collapsars were also proposed as a potentially major source of heavy elements; however, this is difficult to probe through optical observations due to contamination by other emission mechanisms. Here we present observational constraints on <jats:italic>r</jats:italic>-process nucleosynthesis by collapsars based on radio follow-up observations of nearby long gamma-ray bursts (GRBs). We make the hypothesis that late-time radio emission arises from the collapsar wind ejecta responsible for forging <jats:italic>r</jats:italic>-process elements, and consider the constraints that can be set on this scenario using radio observations of a sample of Swift/Burst Alert Telescope GRBs located within 2 Gpc. No radio counterpart was identified in excess of the radio afterglow of the GRBs in our sample. This gives the strictest limit to the collapsar <jats:italic>r</jats:italic>-process contribution of ≲0.2 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> for GRB 060505 and GRB 05826, under the models we considered. Our results additionally constrain energy injection by a long-lived neutron star remnant in some of the considered GRBs. While our results are in tension with collapsars being the majority of <jats:italic>r</jats:italic>-process production sites, the ejecta mass and velocity profile of collapsar winds, and the emission parameters, are not yet well modeled. As such, our results are currently subject to large uncertainties, but further theoretical work could greatly improve them.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Direct-collapse black holes (DCBHs) may be the seeds of the first quasars, over 200 of which have now been detected at <jats:italic>z </jats:italic>&gt; 6. The James Webb Space Telescope (JWST) could detect DCBHs in the near-infrared (NIR) at <jats:italic>z</jats:italic> ≲ 20 and probe the evolution of primordial quasars at their earliest stages, but only in narrow fields that may not capture many of them. Wide-field NIR surveys by Euclid and the Nancy Grace Roman Space Telescope (RST) would enclose far greater numbers of DCBHs but only directly detect them at <jats:italic>z</jats:italic> ≲ 6–8 because of their lower sensitivities. However, their large survey areas will cover thousands of galaxy clusters and massive galaxies that could gravitationally lens flux from DCBHs, boosting them above current Euclid and RST detection limits and revealing more of them than could otherwise be detected. Here, we estimate the minimum number density of strongly lensed DCBHs and supermassive primordial stars required for detection in surveys by Euclid, RST, and JWST at <jats:italic>z</jats:italic> ≲ 20. We find that for reasonable estimates of host halo numbers RST, Euclid, and JWST could potentially find hundreds of strongly lensed DCBHs at <jats:italic>z</jats:italic> = 7–20. RST would detect the most objects at <jats:italic>z</jats:italic> ≲ 10 and JWST would find the most at higher redshifts. Lensed supermassive primordial stars could potentially also be found, but in fewer numbers because of their short lifetimes.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The recent discovery of the extremely lensed Earendel object at <jats:italic>z</jats:italic> = 6.2 is remarkable in that it is likely a single star or stellar multiple, observed within the first billion years of cosmic history. Depending on its mass, which is still uncertain but will soon be more tightly constrained with the James Webb Space Telescope, the Earendel star might even be a member of the first generation of stars, the so-called Population III (Pop III). By combining results from detailed cosmological simulations of the assembly of the first galaxies, including the enrichment of the pristine gas with heavy chemical elements, with assumptions on key stellar parameters, we quantify the probability that Earendel indeed has a Pop III origin. We find that this probability is nonnegligible throughout the mass range inferred for Earendel, specifically ranging from a few percent at the lower-mass end to near unity for some Pop III initial mass function (IMF) models toward the high-mass end of the allowed range. For models that extend the metal-enriched IMF to 500 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, the likelihood of Earendel being a Pop III star stays at the few to 10% level. We discuss the implications of such a discovery for the overall endeavor to probe the hitherto so elusive first stars in the universe.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Long-duration <jats:italic>γ</jats:italic>-ray bursts (GRBs) accompany the collapse of massive stars and carry information about the central engine. However, no 3D models have been able to follow these jets from their birth via black hole (BH) to the photosphere. We present the first such 3D general-relativity magnetohydrodynamic simulations, which span over six orders of magnitude in space and time. The collapsing stellar envelope forms an accretion disk, which drags inwardly the magnetic flux that accumulates around the BH, becomes dynamically important, and launches bipolar jets. The jets reach the photosphere at ∼10<jats:sup>12</jats:sup> cm with an opening angle<jats:italic> θ</jats:italic> <jats:sub> <jats:italic>j</jats:italic> </jats:sub> ∼ 6° and a Lorentz factor Γ<jats:sub> <jats:italic>j</jats:italic> </jats:sub> ≲ 30, unbinding ≳90% of the star. We find that (i) the disk–jet system spontaneously develops misalignment relative to the BH rotational axis. As a result, the jet wobbles with an angle <jats:italic>θ</jats:italic> <jats:sub> <jats:italic>t</jats:italic> </jats:sub> ∼ 12°, which can naturally explain quiescent times in GRB lightcurves. The effective opening angle for detection <jats:italic>θ</jats:italic> <jats:sub> <jats:italic>j</jats:italic> </jats:sub> + <jats:italic>θ</jats:italic> <jats:sub> <jats:italic>t</jats:italic> </jats:sub> suggests that the intrinsic GRB rate is lower by an order of magnitude than standard estimates. This suggests that successful GRBs are rarer than currently thought and emerge in only ∼0.1% of supernovae Ib/c, implying that jets are either not launched or choked inside most supernova Ib/c progenitors. (ii) The magnetic energy in the jet decreases due to mixing with the star, resulting in jets with a hybrid composition of magnetic and thermal components at the photosphere, where ∼10% of the gas maintains magnetization <jats:italic>σ</jats:italic> ≳ 0.1. This indicates that both a photospheric component and reconnection may play a role in the prompt emission.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report observations from the Hubble Space Telescope (HST) of Cepheid variables in the host galaxies of 42 Type Ia supernovae (SNe Ia) used to calibrate the Hubble constant (<jats:italic>H</jats:italic> <jats:sub>0</jats:sub>). These include the complete sample of all suitable SNe Ia discovered in the last four decades at redshift <jats:italic>z</jats:italic> ≤ 0.01, collected and calibrated from ≥1000 HST orbits, more than doubling the sample whose size limits the precision of the direct determination of <jats:italic>H</jats:italic> <jats:sub>0</jats:sub>. The Cepheids are calibrated geometrically from Gaia EDR3 parallaxes, masers in NGC 4258 (here tripling that sample of Cepheids), and detached eclipsing binaries in the Large Magellanic Cloud. All Cepheids in these anchors and SN Ia hosts were measured with the same instrument (WFC3) and filters (<jats:italic>F555W</jats:italic>, <jats:italic>F814W</jats:italic>, <jats:italic>F160W</jats:italic>) to negate zero-point errors. We present multiple verifications of Cepheid photometry and six tests of background determinations that show Cepheid measurements are accurate in the presence of crowded backgrounds. The SNe Ia in these hosts calibrate the magnitude–redshift relation from the revised Pantheon+ compilation, accounting here for covariance between all SN data and with host properties and SN surveys matched throughout to negate systematics. We decrease the uncertainty in the local determination of <jats:italic>H</jats:italic> <jats:sub>0</jats:sub> to 1 km s<jats:sup>−1</jats:sup> Mpc<jats:sup>−1</jats:sup> including systematics. We present results for a comprehensive set of nearly 70 analysis variants to explore the sensitivity of <jats:italic>H</jats:italic> <jats:sub>0</jats:sub> to selections of anchors, SN surveys, redshift ranges, the treatment of Cepheid dust, metallicity, form of the period–luminosity relation, SN color, peculiar-velocity corrections, sample bifurcations, and simultaneous measurement of the expansion history. Our baseline result from the Cepheid–SN Ia sample is <jats:italic>H</jats:italic> <jats:sub>0</jats:sub> = 73.04 ± 1.04 km s<jats:sup>−1</jats:sup> Mpc<jats:sup>−1</jats:sup>, which includes systematic uncertainties and lies near the median of all analysis variants. We demonstrate consistency with measures from HST of the TRGB between SN Ia hosts and NGC 4258, and include them simultaneously to yield 72.53 ± 0.99 km s<jats:sup>−1</jats:sup> Mpc<jats:sup>−1</jats:sup>. The inclusion of high-redshift SNe Ia yields <jats:italic>H</jats:italic> <jats:sub>0</jats:sub> = 73.30 ± 1.04 km s<jats:sup>−1</jats:sup> Mpc<jats:sup>−1</jats:sup> and <jats:italic>q</jats:italic> <jats:sub>0</jats:sub> = −0.51 ± 0.024. We find a 5<jats:italic>σ</jats:italic> difference with the prediction of <jats:italic>H</jats:italic> <jats:sub>0</jats:sub> from Planck cosmic microwave background observations under ΛCDM, with no indication that the discrepancy arises from measurement uncertainties or analysis variations considered to date. The source of this now long-standing discrepancy between direct and cosmological routes to determining <jats:italic>H</jats:italic> <jats:sub>0</jats:sub> remains unknown.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We create a photoionization model embedded in the turbulent interstellar medium (ISM) by using the state-of-the-art Messenger Monte Carlo MAPPINGS V code (M<jats:sup>3</jats:sup>) in conjunction with the CMFGEN stellar atmosphere model. We show that the turbulent ISM causes the inhomogeneity of electron temperature and density within the nebula. The fluctuation in the turbulent ISM creates complex ionization structures seen in nearby nebulae. The inhomogeneous density distribution within the nebula creates a significant scatter on the spatially resolved standard optical diagnostic diagrams, which cannot be represented by the spherical constant-density photoionization model. We analyze the dependence of different optical emission lines on the complexity of nebular geometry, finding that the emission lines residing on the nebular boundary are highly sensitive to the complexity of nebular geometry, while the emission lines produced throughout the nebula are sensitive to the density distribution of the ISM within the nebula. Our fractal photoionization model demonstrates that a complex nebular geometry is required for the accurate modeling of H <jats:sc>ii</jats:sc> regions and emission-line galaxies, especially for the high-redshift galaxies, where the ISM is highly turbulent based on increasing observational evidence.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>To understand the formation of quiescent solar prominences, the origin of their magnetic field structures, i.e., magnetic flux ropes (MFRs), must be revealed. We use three-dimensional magnetofriction simulations in a spherical subdomain to investigate the role of typical supergranular motions in the long-term formation of a prominence magnetic field. Time-dependent horizontal supergranular motions with and without the effect of Coriolis force are simulated on the solar surface via Voronoi tessellation. The vortical motions by the Coriolis effect at boundaries of supergranules inject magnetic helicity into the corona. The helicity is transferred and accumulated along the polarity inversion line (PIL) as a strongly sheared magnetic field via helicity condensation. The diverging motions of supergranules converge opposite magnetic polarities at the PIL and drive the magnetic reconnection between footpoints of the sheared magnetic arcades to form an MFR. The magnetic network, negative-helicity MFR in the northern hemisphere, and fragmented-to-continuous formation process of magnetic dip regions are in agreement with observations. Although diverging supergranulations, differential rotation, and meridional flows are included, the simulation without the Coriolis effect cannot produce an MFR or sheared arcades to host a prominence. Therefore, Coriolis force is a key factor for helicity injection and the formation of magnetic structures of quiescent solar prominences.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) 19-beam tracking observational mode, high-sensitivity and high-velocity-resolution H <jats:sc>i</jats:sc> spectral lines have been observed toward the high-mass star-forming region G176.51+00.20. This is a pilot study searching for H <jats:sc>i</jats:sc> narrow-line self-absorption (HINSA) toward high-mass star-forming regions where bipolar molecular outflows have been detected. This work is confined to the central seven beams of FAST. Two HINSA components are detected in all seven beams, which correspond to a strong CO emission region (SCER; with a velocity of ∼−18 km s<jats:sup>−1</jats:sup>) and a weak CO emission region (WCER; with a velocity of ∼−3 km s<jats:sup>−1</jats:sup>). The SCER detected in Beam 3 is probably more suitably classified as a WCER. In the SCER, the HINSA is probably associated with the molecular material traced by the CO. The fractional abundance of HINSA ranges from ∼1.1 × 10<jats:sup>−3</jats:sup> to ∼2.6 × 10<jats:sup>−2</jats:sup>. Moreover, the abundance of HINSA in Beam 1 is lower than that in the surrounding beams (i.e., Beams 2 and 4–7). This possible ring could be caused by the ionization of H <jats:sc>i</jats:sc> or the relatively rapid conversion from H <jats:sc>i</jats:sc> to H<jats:sub>2</jats:sub> in the higher-density inner region. In the WCER (including Beam 3 in the SCER), the HINSA is probably not associated with CO clouds, but with CO-dark or CO-faint gas.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The motion of faint propagating disturbances (PDs) in the solar corona reveals an intricate structure that must be defined by the magnetic field. Applied to quiet Sun observations by the Atmospheric Imaging Assembly (AIA)/Solar Dynamics Observatory (SDO), a novel method reveals a cellular network, with cells of typical diameters 50″ in the cool 304 Å channel and 100″ in the coronal 193 Å channel. The 193 Å cells can overlie several 304 Å cells, although both channels share common source and sink regions. The sources are points, or narrow corridors, of divergence that occupy the centers of cells. They are significantly aligned with photospheric network features and enhanced magnetic elements. This shows that the bright network is important to the production of PDs and confirms that the network is host to the source footpoint of quiet coronal loops. The other footpoint, or the sinks of the PDs, form the boundaries of the coronal cells. These are not significantly aligned with the photospheric network—they are generally situated above the dark internetwork photosphere. They form compact points or corridors, often without an obvious signature in the underlying photosphere. We argue that these sink points can either be concentrations of closed field footpoints associated with minor magnetic elements in the internetwork or concentrations of an upward-aligned open field. The link between the coronal velocity and magnetic fields is strengthened by comparison with a magnetic extrapolation, which shows several general and specific similarities, thus the velocity maps offer a valuable additional constraint on models.</jats:p>