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<jats:title>Abstract</jats:title> <jats:p>Visible light observations from the Wide-field Imager for Solar PRobe (WISPR) aboard the Parker Solar Probe (PSP) mission offer a unique opportunity to study the dust environment near the Sun. The existence of a dust-free zone (DFZ) around stars was postulated almost a century ago. Despite numerous attempts to detect it from as close as 0.3 au, observational evidence of a circumsolar DFZ has remained elusive. Analysis of WISPR images obtained from heliocentric distances between 13.3–53.7 <jats:italic>R</jats:italic> <jats:sub>⊙</jats:sub> over multiple PSP orbits shows a gradually decreasing brightness gradient along the symmetry axis of the F-corona for coronal heights between 19 and 9 <jats:italic>R</jats:italic> <jats:sub>⊙</jats:sub>. Below 9 <jats:italic>R</jats:italic> <jats:sub>⊙</jats:sub>, the gradient reverses its trend, approaching the radial dependence exhibited at heights above 19 <jats:italic>R</jats:italic> <jats:sub>⊙</jats:sub>. After taking into account the effects of both the electron corona background and the nonresolved starlight, the WISPR observations down to 4 <jats:italic>R</jats:italic> <jats:sub>⊙</jats:sub> are consistent with forward-modeling simulations of the F-corona brightness within [−6, 5]% if a circumsolar region of depleted dust density between 19 and 5 <jats:italic>R</jats:italic> <jats:sub>⊙</jats:sub> enclosing a DFZ is considered. In addition, we show, for the first time, that the F-corona brightness inward of about 15 <jats:italic>R</jats:italic> <jats:sub>⊙</jats:sub> depends on the observer’s location for observing distances below 35 <jats:italic>R</jats:italic> <jats:sub>⊙</jats:sub>.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The purpose of this work is to extend a sample of accurately modeled, benchmark-grade eclipsing binaries (EBs) with accurately determined masses and radii. We select four “well-behaved” Kepler binaries, KIC 2306740, KIC 4076952, KIC 5193386 and KIC 5288543, each with at least eight double-lined spectra from the Apache Point Observatory Galactic Evolution Experiment instrument that is part of the Sloan Digital Sky Surveys III and IV, and from the Hobby–Eberly High Resolution Spectrograph. We obtain masses and radii with uncertainties of 2.5% or less for all four systems. Three of these systems have orbital periods longer than 9 days, and thus populate an undersampled region of the parameter space for extremely well-characterized detached EBs. We compare the derived masses and radii against <jats:sc>mesa mist</jats:sc> isochrones to determine the ages of the systems. All systems were found to be coeval, showing that the results are consistent across <jats:sc>mesa mist</jats:sc> and <jats:sc>phoebe</jats:sc>.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a new investigation of the intergalactic medium near reionization using dark gaps in the Ly<jats:italic>β</jats:italic> forest. With its lower optical depth, Ly<jats:italic>β</jats:italic> offers a potentially more sensitive probe to any remaining neutral gas compared to the commonly used Ly<jats:italic>α</jats:italic> line. We identify dark gaps in the Ly<jats:italic>β</jats:italic> forest using spectra of 42 QSOs at <jats:italic>z</jats:italic> <jats:sub>em</jats:sub> &gt; 5.5, including new data from the XQR-30 VLT Large Programme. Approximately 40% of these QSO spectra exhibit dark gaps longer than 10 <jats:italic>h</jats:italic> <jats:sup>−1</jats:sup> Mpc at <jats:italic>z</jats:italic> ≃ 5.8. By comparing the results to predictions from simulations, we find that the data are broadly consistent both with models where fluctuations in the Ly<jats:italic>α</jats:italic> forest are caused solely by ionizing ultraviolet background fluctuations and with models that include large neutral hydrogen patches at <jats:italic>z</jats:italic> &lt; 6 due to a late end to reionization. Of particular interest is a very long (<jats:italic>L</jats:italic> = 28 <jats:italic>h</jats:italic> <jats:sup>−1</jats:sup> Mpc) and dark (<jats:italic>τ</jats:italic> <jats:sub>eff</jats:sub> ≳ 6) gap persisting down to <jats:italic>z</jats:italic> ≃ 5.5 in the Ly<jats:italic>β</jats:italic> forest of the <jats:italic>z</jats:italic> = 5.85 QSO PSO J025−11. This gap may support late reionization models with a volume-weighted average neutral hydrogen fraction of 〈<jats:italic>x</jats:italic> <jats:sub>H I</jats:sub>〉 ≳ 5% by <jats:italic>z</jats:italic> = 5.6. Finally, we infer constraints on 〈<jats:italic>x</jats:italic> <jats:sub>H I</jats:sub>〉 over 5.5 ≲ <jats:italic>z</jats:italic> ≲ 6.0 based on the observed Ly<jats:italic>β</jats:italic> dark gap length distribution and a conservative relationship between gap length and neutral fraction derived from simulations. We find 〈<jats:italic>x</jats:italic> <jats:sub>H I</jats:sub>〉 ≤ 0.05, 0.17, and 0.29 at <jats:italic>z</jats:italic> ≃ 5.55, 5.75, and 5.95, respectively. These constraints are consistent with models where reionization ends significantly later than <jats:italic>z</jats:italic> = 6.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The propagation direction and true velocity of a solar coronal mass ejection, which are among the most decisive factors for its geo-effectiveness, are difficult to determine through single-perspective imaging observations. Here we show that Sun-as-a-star spectroscopic observations, together with imaging observations, could allow us to solve this problem. Using observations of the Extreme Ultraviolet Variability Experiment onboard the Solar Dynamics Observatory, we found clear blueshifted secondary emission components in extreme-ultraviolet spectral lines during a solar eruption on 2021 October 28. From simultaneous imaging observations, we found that the secondary components are caused by a mass ejection from the flare site. We estimated the line-of-sight (LOS) velocity of the ejecta from both the double Gaussian fitting method and the red-blue asymmetry analysis. The results of both methods agree well with each other, giving an average LOS velocity of the plasma of ∼423 km s<jats:sup>−1</jats:sup>. From the 304 Å image series taken by the Extreme ultraviolet Imager onboard the Solar Terrestrial Relation Observatory-A (STEREO-A) spacecraft, we estimated the plane-of-sky velocity from the STEREO-A viewpoint to be around 587 km s<jats:sup>−1</jats:sup>. The full velocity of the bulk motion of the ejecta was then computed by combining the imaging and spectroscopic observations, which turns out to be around 596 km s<jats:sup>−1</jats:sup> with an angle of 42.°4 to the west of the Sun–Earth line and 16.°0 south to the ecliptic plane.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present an ALMA-Herschel joint analysis of sources detected by the ALMA Lensing Cluster Survey (ALCS) at 1.15 mm. Herschel/PACS and SPIRE data at 100–500 <jats:italic>μ</jats:italic>m are deblended for 180 ALMA sources in 33 lensing cluster fields that are detected either securely (141 sources; in our main sample) or tentatively at S/N ≥ 4 with cross-matched HST/Spitzer counterparts, down to a delensed 1.15 mm flux density of ∼0.02 mJy. We performed far-infrared spectral energy distribution modeling and derived the physical properties of dusty star formation for 125 sources (109 independently) that are detected at &gt;2<jats:italic>σ</jats:italic> in at least one Herschel band. A total of 27 secure ALCS sources are not detected in any Herschel bands, including 17 optical/near-IR-dark sources that likely reside at <jats:italic>z</jats:italic> = 4.2 ± 1.2. The 16th, 50th, and 84th percentiles of the redshift distribution are 1.15, 2.08, and 3.59, respectively, for ALCS sources in the main sample, suggesting an increasing fraction of <jats:italic>z</jats:italic> ≃ 1 − 2 galaxies among fainter millimeter sources (<jats:italic>f</jats:italic> <jats:sub>1150</jats:sub> ∼ 0.1 mJy). With a median lensing magnification factor of <jats:inline-formula> <jats:tex-math> <?CDATA $\mu ={2.6}_{-0.8}^{+2.6}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>μ</mml:mi> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>2.6</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.8</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2.6</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac6e3fieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, ALCS sources in the main sample exhibit a median intrinsic star formation rate of <jats:inline-formula> <jats:tex-math> <?CDATA ${94}_{-54}^{+84}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>94</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>54</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>84</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac6e3fieqn2.gif" xlink:type="simple" /> </jats:inline-formula> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> yr<jats:sup>−1</jats:sup>, lower than that of conventional submillimeter galaxies at similar redshifts by a factor of ∼3. Our study suggests weak or no redshift evolution of dust temperature with <jats:italic>L</jats:italic> <jats:sub>IR</jats:sub> &lt; 10<jats:sup>12</jats:sup> <jats:italic>L</jats:italic> <jats:sub>⊙</jats:sub> galaxies within our sample at <jats:italic>z</jats:italic> ≃ 0 − 2. At <jats:italic>L</jats:italic> <jats:sub>IR</jats:sub> &gt; 10<jats:sup>12</jats:sup> <jats:italic>L</jats:italic> <jats:sub>⊙</jats:sub>, the dust temperatures show no evolution across <jats:italic>z</jats:italic> ≃ 1–4 while being lower than those in the local universe. For the highest-redshift source in our sample (<jats:italic>z</jats:italic> = 6.07), we can rule out an extreme dust temperature (&gt;80 K) that was reported for MACS0416 Y1 at <jats:italic>z</jats:italic> = 8.31.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a detailed X-ray spectral analysis of the narrow-line Seyfert 1 galaxy I Zwicky 1, for which a sequence of X-ray flares were detected during a long, simultaneous observation acquired with XMM-Newton and NuSTAR. We determine the key parameters of the inner accretion disk and hot corona in the context of the disk reflection model, which successfully captures the evolution of the X-ray corona during the X-ray flare. Using a thermal Comptonization continuum model, we confirm that the corona rapidly cooled from ∼200 to ∼15 keV, likely a consequence of strong pair production and runaway in a disk-like corona during the X-ray flare, when the nonthermal electron fraction rapidly increased. We detect multiple variable blueshifted absorption features arising from outflowing material along the line of sight to I Zwicky 1, which we associated with ionized winds and ultrafast outflows. One of the ionized winds may be newly launched just after the X-ray flare. During the 5 days of NuSTAR observations, the ionization state and velocity of these outflows followed a relation of the form <jats:italic>ξ</jats:italic> ∼ <jats:italic>v</jats:italic> <jats:sub> <jats:italic>w</jats:italic> </jats:sub> <jats:sup>3.24</jats:sup>, as expected from a super-Eddington wind. Comparison with molecular gas and warm ionized gas observations suggests that the kinematics of the ionized winds are consistent with a sufficiently cooled, momentum-driven outflow. Considering the dynamical feedback from these outflows can account for the significantly undermassive black hole in I Zwicky 1.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Recent ground- and space-based observations show that stars with multiple planets are common in the Galaxy. Most of these observational methods are biased toward detecting large planets near to their host stars. Because of these observational biases, these systems can hide small, close-in planets or far-orbiting (big or small) companions. These planets can still exert dynamical influence on known planets and have such influence exerted on them in turn. In certain configurations, this influence can destabilize the system; in others, the star’s gravitational influence can instead further stabilize the system. For example, in systems with planets close to the host star, effects arising from general relativity can help to stabilize the configuration. We derive criteria for hidden planets orbiting both beyond and within known planets that quantify how strongly general relativistic effects can stabilize systems that would otherwise be unstable. As a proof of concept, we investigate the several planets in a system based on Kepler-56 and show that the outermost planet will not disrupt the system even at high eccentricities, and we show that an Earth-radius planet could be stable within this system if it orbits below 0.08 au. Furthermore, we provide specific predictions to known observed systems by constraining the parameter space of possible hidden planets.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>This work presents a new detection of H<jats:sub>2</jats:sub> absorption arising in a high-velocity cloud associated with either the Milky Way or the Large Magellanic Cloud (LMC). The absorber was found in an archival Far Ultraviolet Spectroscopic Explorer spectrum of the LMC star Sk-70°32. This is the fifth well-characterized H<jats:sub>2</jats:sub> absorber to be found in the Milky Way’s halo and the second such absorber outside the Magellanic Stream and Bridge. The absorber has a local standard of rest central velocity of +140 km s<jats:sup>−1</jats:sup> and a H<jats:sub>2</jats:sub> column density of 10<jats:sup>17.5</jats:sup> cm<jats:sup>−2</jats:sup>. It is most likely part of a cool and relatively dense inclusion (<jats:italic>T</jats:italic> ≈ 75 K, <jats:italic>n</jats:italic> <jats:sub>H</jats:sub> ∼ 100 cm<jats:sup>−3</jats:sup>) in a warmer and more diffuse halo cloud. This halo cloud may be part of a still-rising Milky Way Galactic fountain flow or an outflow from the Large Magellanic Cloud.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>DI Cha A is K0-type pre-main-sequence star, the brightest component of a quadruple stellar system. Here we report on a detailed study of this star based on archival VLTI/MIDI and VLTI/PIONIER infrared interferometric observations, as well as optical-infrared photometric monitoring from ground-based and space-born instruments. We determined the structure of the circumstellar disk by fitting simultaneously the interferometric visibilities and the spectral energy distribution, using both analytical models and the radiative transfer code RADMC-3D. The modeling revealed that the radial density distribution of the disk appears to have a gap between 0.21 and 3.0 au. The inner ring, whose inner size coincides with the sublimation radius, is devoid of small, submicrometer-sized dust grains. The inner edge of the outer disk features a puffed-up rim, typically seen in intermediate-mass stars. Grain growth, although less progressed, was also detected in the outer disk. The inner ring is variable at mid-infrared wavelengths on both daily and annual timescales, while the star stays remarkably constant in the optical, pointing to geometrical or accretion changes in the disk as possible explanations for the flux variations.</jats:p>