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<jats:title>Abstract</jats:title> <jats:p>We present results of subarcsec Atacama Large Millimeter/submillimeter Array observations of CO(2–1) and CO(5–4) toward a massive main-sequence galaxy at <jats:italic>z</jats:italic> = 1.45 in the Subaru-XMM/Newton Deep Survey/UDS field, aiming at examining the internal distribution and properties of molecular gas in the galaxy. Our target galaxy consists of the bulge and disk, and has a UV clump in the Hubble Space Telescope images. The CO emission lines are clearly detected, and the CO(5–4)/CO(2–1) flux ratio (<jats:italic>R</jats:italic> <jats:sub>52</jats:sub>) is ∼1, similar to that of the Milky Way. Assuming a metallicity-dependent CO-to-H<jats:sub>2</jats:sub> conversion factor and a CO(2–1)/CO(1–0) flux ratio of 2 (the Milky Way value), the molecular gas mass and the gas-mass fraction (<jats:italic>f</jats:italic> <jats:sub>gas</jats:sub> = ratio of the molecular gas mass to the molecular gas mass + stellar mass) are estimated to be ∼1.5 × 10<jats:sup>11</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> and ∼0.55, respectively. We find that <jats:italic>R</jats:italic> <jats:sub>52</jats:sub> peak coincides with the position of the UV clump and that its value is approximately twice higher than the galactic average. This result implies a high gas density and/or high temperature in the UV clump, which qualitatively agrees with a numerical simulation of a clumpy galaxy. The CO(2–1) distribution is well represented by a rotating-disk model, and its half-light radius is ∼2.3 kpc. Compared to the stellar distribution, the molecular gas is more concentrated in the central region of the galaxy. We also find that <jats:italic>f</jats:italic> <jats:sub>gas</jats:sub> decreases from ∼0.6 at the galactic center to ∼0.2 at three times the half-light radius, indicating that the molecular gas is distributed in the more central region of the galaxy than stars and seems to be associated with the bulge rather than with the stellar disk.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Observations of scattered light and thermal emission from hot Jupiter exoplanets have suggested the presence of inhomogeneous aerosols in their atmospheres. 3D general circulation models (GCMs) that attempt to model the effects of aerosols have been developed to understand the physical processes that underlie their dynamical structures. In this work, we investigate how different approaches to aerosol modeling in GCMs of hot Jupiters affect high-resolution thermal emission spectra throughout the duration of the planet’s orbit. Using results from a GCM with temperature-dependent cloud formation, we calculate spectra of a representative hot Jupiter with different assumptions regarding the vertical extent and thickness of clouds. We then compare these spectra to models in which clouds are absent or simply post-processed (i.e., added subsequently to the completed clear model). We show that the temperature-dependent treatment of clouds in the GCM produces high-resolution emission spectra that are markedly different from the clear and post-processed cases—both in the continuum flux levels and line profiles—and that increasing the vertical extent and thickness of clouds leads to bigger changes in these features. We evaluate the net Doppler shifts of the spectra induced by global winds and the planet’s rotation and show that they are strongly phase dependent, especially for models with thicker and more extended clouds. This work further demonstrates the importance of radiative feedback in cloudy atmospheric models of hot Jupiters, as this can have a significant impact on interpreting spectroscopic observations of exoplanet atmospheres.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Polar crown filaments (PCFs) are formed above the polarity inversion line, which separates unipolar polar fields and the nearest dispersed fields. They are important features in studying solar polar fields and their cyclical variations. Due to the relatively weak field strength and projection effects, measuring polar magnetic fields is more difficult than obtaining the field strengths concentrated in active regions at lower latitudes. “Rush-to-the-pole” of PCFs represent the progress of unipolar polar fields from the previous solar cycle being canceled by the dispersed fields generated in the current cycle. Such progress is a good indicator of the polarity reversal in the polar areas and a precursor for the solar maximum. In this study, PCFs are identified from a 100 yr archive, covering cycles 16–24. This archive consists of full-disk H<jats:italic>α</jats:italic> images obtained from the Kodaikanal Solar Observatory of the Indian Institute of Astrophysics, Kanzelhöhe Solar Observatory, and Big Bear Solar Observatory. The poleward migration speeds are measured and show an obvious asymmetry in the northern and southern hemispheres. In addition, our results show that the PCFs usually reach their highest latitudes first in the northern hemisphere, except cycle 17. Similarly, previous studies show that the magnetic field reversed first at the north pole in six out of nine cycles. We also compare the temporal variations of PCF migration and the latitude gradient factor of the differential rotation, which shows a trend in the southern hemisphere. Moreover, the migration speed of PCFs does not seem to be well correlated with the maximum sunspot numbers.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The polar precursor method is widely considered to be the most robust physically motivated method to predict the amplitude of an upcoming solar cycle. It uses indicators of the magnetic field concentrated near the poles around the sunspot minimum. Here, we present an extensive analysis of the performance of various such predictors, based on both observational data (Wilcox Solar Observatory (WSO) magnetograms, Mount Wilson Observatory polar faculae counts, and Pulkovo <jats:italic>A</jats:italic>(<jats:italic>t</jats:italic>) index) and outputs (polar cap magnetic flux and global dipole moment) of various existing flux transport dynamo models. We calculate Pearson correlation coefficients (<jats:italic>r</jats:italic>) of the predictors with the next cycle amplitude as a function of time measured from several solar cycle landmarks: setting <jats:italic>r</jats:italic> = 0.8 as a lower limit for acceptable predictions, we find that observations and models alike indicate that the earliest time when the polar predictor can be safely used is 4 yr after the polar field reversal. This is typically 2–3 yr before the solar minimum and about 7 yr before the predicted maximum, considerably extending the usual temporal scope of the polar precursor method. Reevaluating the predictors another 3 yr later, at the time of the solar minimum, further increases the correlation level to <jats:italic>r</jats:italic> ≳ 0.9. As an illustration of the result, we determine the predicted amplitude of Cycle 25 based on the value of the WSO polar field at the now official minimum date of 2019 December as 126 ± 3. A forecast based on the value in early 2017, 4 yr after the polar reversal would have only differed from this final prediction by 3.1 ± 14.7%.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The equatorial current sheets outside the light cylinder (LC) are thought to be promising sites of high-energy emission based on the results of recent numerical simulations. We explore the pulsar light curves and energy spectra by computing the curvature radiation based on the FIDO magnetospheres. The FIDO magnetospheres with a near force-free regime inside the LC and a finite but high conductivity outside the LC are constructed using a spectral algorithm. The pulsar high-energy emission properties are explored by integrating the trajectories of the test particles under the influence of both the accelerating electric field and the curvature radiation losses. As an application, we compare the predicted energy-dependent light curves and energy spectra with those of the Crab and Vela pulsars published in the Fermi 2PC catalog. We find that the observed characteristics of the light curves and energy spectra from the Crab and Vela pulsars can be well reproduced by the FIDO model.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The question why the solar corona is much hotter than the visible solar surface still puzzles solar researchers. Most theories of the coronal heating involve a tight coupling between the coronal magnetic field and the associated thermal structure. This coupling is based on two facts: (i) the magnetic field is the main source of the energy in the corona and (ii) the heat transfer preferentially happens along the magnetic field, while is suppressed across it. However, most of the information about the coronal heating is derived from the analysis of extreme ultraviolet or soft X-ray emissions, which are not explicitly sensitive to the magnetic field. This paper employs another electromagnetic channel—the sunspot-associated microwave gyroresonant emission, which is explicitly sensitive to both the magnetic field and thermal plasma. We use nonlinear force-free field reconstructions of the magnetic skeleton dressed with a thermal structure as prescribed by a field-aligned hydrodynamics to constrain the coronal heating model. We demonstrate that the microwave gyroresonant emission is extraordinarily sensitive to details of the coronal heating. We infer heating model parameters consistent with observations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the first detailed observational picture of a possible ongoing massive cluster hierarchical assembly in the Galactic disk as revealed by the analysis of the stellar full phase space (3D positions and kinematics and spectro-photometric properties) of an extended area (6° diameter) surrounding the well-known <jats:italic>h</jats:italic> and <jats:italic>χ</jats:italic> Persei double stellar cluster in the Perseus Arm. Gaia-EDR3 shows that the area is populated by seven comoving clusters, three of which were previously unknown, and by an extended and quite massive (<jats:italic>M</jats:italic> ∼ 10<jats:sup>5</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>) halo. All stars and clusters define a complex structure with evidence of possible mutual interactions in the form of intra-cluster overdensities and/or bridges. They share the same chemical abundances (half-solar metallicity) and age (<jats:italic>t</jats:italic> ∼ 20 Myr) within a small confidence interval and the stellar density distribution of the surrounding diffuse stellar halo resembles that of a cluster-like stellar system. The combination of these pieces of evidence suggests that stars distributed within a few degrees from <jats:italic>h</jats:italic> and <jats:italic>χ</jats:italic> Persei are part of a common, substructured stellar complex that we named LISCA I. Comparison with results obtained through direct <jats:italic>N</jats:italic>-body simulations suggest that LISCA I may be at an intermediate stage of an ongoing cluster assembly that can eventually evolve in a relatively massive (a few times 10<jats:sup>5</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>) stellar system. We argue that such a cluster formation mechanism may be quite efficient in the Milky Way and disk-like galaxies and, as a consequence, it has a relevant impact on our understanding of cluster formation efficiency as a function of the environment and redshift.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present evidence that a magnetic flux rope was formed before a coronal mass ejection (CME) and its associated long-duration flare during a pair of preceding confined eruptions and associated impulsive flares in a compound event in NOAA Active Region 12371. Extreme-ultraviolet images and the extrapolated nonlinear force-free field show that the first two (impulsive) flares, SOL2015-06-21T01:42, result from the confined eruption of highly sheared low-lying flux, presumably a seed flux rope. The eruption spawns a vertical current sheet, where magnetic reconnection creates flare ribbons and loops, a nonthermal microwave source, and a sigmoidal hot channel that can only be interpreted as a magnetic flux rope. Until the subsequent long-duration flare, SOL2015-06-21T02:36, the sigmoid’s elbows expand, while its center remains stationary, suggesting nonequilibrium but not yet instability. The “flare reconnection” during the confined eruptions acts like “tether-cutting reconnection” whose flux feeding of the rope leads to instability. The subsequent full eruption is seen as an accelerated rise of the entire hot channel, seamlessly evolving into the fast halo CME. Both the confined and ejective eruptions are consistent with the onset of the torus instability in the dipped decay index profile that results from the region’s two-scale magnetic structure. We suggest that the formation or enhancement of a nonequilibrium but stable flux rope by confined eruptions is a generic process occurring prior to many CMEs.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Compact starburst galaxies are thought to include many or most of the galaxies from which substantial Lyman continuum emission can escape into the intergalactic medium. Li &amp; Malkan used Sloan Digital Sky Survey photometry to find a population of such starburst galaxies at <jats:italic>z</jats:italic> ∼ 0.5. They were discovered by their extremely strong [O <jats:sc>iii</jats:sc>] <jats:italic>λλ</jats:italic>4959+5007 emission lines, which produce a clearly detectable excess brightness in the <jats:italic>i</jats:italic> bandpass, compared with surrounding filters. We therefore used the Hubble Space Telescope (HST)/COS spectrograph to observe two of the newly discovered <jats:italic>i</jats:italic>-band excess galaxies around their Lyman limits. One has strongly detected continuum below its Lyman limit, corresponding to a relative escape fraction of ionizing photons of 20% ± 2%. The other, which is less compact in UV imaging, has a 2<jats:italic>σ</jats:italic> upper limit to its Lyman escape fraction of &lt;5%. Before the UV spectroscopy, the existing data could not distinguish these two galaxies. Although a sample of two is hardly sufficient for statistical analysis, it shows the possibility that some fraction of these strong [O <jats:sc>iii</jats:sc>] emitters as a class have ionizing photons escaping. The differences might be determined by the luck of our particular viewing geometry. Obtaining the HST spectroscopy revealed that the Lyman-continuum-emitting galaxy differs in having no central absorption in its prominent Ly<jats:italic>α</jats:italic> emission-line profile. The other target, with no escaping Lyman continuum, shows the more common double-peaked Ly<jats:italic>α</jats:italic> emission.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report the most detailed 1–3 GHz radio continuum emission map of the nearest region of massive-star formation, the Carina Nebula. As part of a large program with the Australia Telescope Compact Array, we have covered ∼12 deg<jats:sup>2</jats:sup>, achieving an angular resolution of ∼16″, representing the largest and most complete map of the radio continuum to date. Our continuum map shows a spectacular and complex distribution of emission across the nebula, with multiple structures such as filaments, shells, and fronts across a wide range of size scales. The ionization fronts have advanced far into the southern and northern region of the Galactic plane, as fronts are clearly detected at distances of ∼80 pc from the stellar clusters in the center. We estimated an ionization photon luminosity <jats:italic>Q</jats:italic> <jats:sub>H</jats:sub> = (7. 8 ± 0.8) × 10<jats:sup>50</jats:sup> s<jats:sup>−1</jats:sup>, which corresponds to ∼85% of the total value obtained from stellar population studies. Thus, approximately 15% of the ionizing flux has escaped from the nebula into the diffuse Galactic interstellar medium. Comparison between radio continuum and the hydrogen atomic and molecular gas maps offers a clear view of the bipolar outflow driven by the energy released by the massive stellar clusters that also affects the fraction of molecular gas across the nebula. Comparison between 8 <jats:italic>μ</jats:italic>m and 70 <jats:italic>μ</jats:italic>m emission maps and the radio continuum reveals how the hot gas permeates through the molecular cloud; shapes the material into features such as pillars, small shells, and arc-like structures; and ultimately escapes.</jats:p>