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<jats:title>Abstract</jats:title> <jats:p>The origin of enhanced abundance of heavy elements observed in the surface chemical composition of carbon-enhanced metal-poor (CEMP) stars still remains poorly understood. Here, we present detailed abundance analysis of seven CEMP stars based on high-resolution (<jats:italic>R</jats:italic> ∼ 50,000) spectra that reveal enough evidence of asymptotic giant branch (AGB) stars being possible progenitors for these objects. For the objects HE 0110−0406, HE 1425−2052, and HE 1428−1950, we present for the first time a detailed abundance analysis. Our sample is found to consist of one metal-poor ([Fe/H] &lt; −1.0) and six very metal-poor ([Fe/H] &lt; −2.0) stars with enhanced carbon and neutron-capture elements. We have critically analyzed the observed abundance ratios of [O/Fe], [Sr/Ba], and [hs/ls] and examined the possibility of AGB stars being possible progenitors. The abundance of oxygen estimated in the program stars is characteristic of AGB progenitors except for HE 1429−0551 and HE 1447+0102. The estimated values of [Sr/Ba] and [hs/ls] ratios also support AGB stars as possible progenitors. The locations of the program stars in the absolute carbon abundance <jats:italic>A</jats:italic>(C) versus [Fe/H] diagram, along with the Group I objects, hint at the binary nature of the object. We have studied the chemical enrichment histories of the program stars based on abundance ratios [Mg/C], [Sc/Mn], and [C/Cr]. Using [C/N] and <jats:sup>12</jats:sup>C/<jats:sup>13</jats:sup>C ratios, we have examined whether any internal mixing had modified their surface chemical compositions. Kinematic analysis shows that the objects HE 0110−0406 and HE 1447+0102 are thick-disk objects and the remaining five objects belong to the halo population of the Galaxy.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present new stellar mass functions at <jats:italic>z</jats:italic> ∼ 6, <jats:italic>z</jats:italic> ∼ 7, <jats:italic>z</jats:italic> ∼ 8, <jats:italic>z</jats:italic> ∼ 9 and, for the first time, <jats:italic>z</jats:italic> ∼ 10, constructed from ∼800 Lyman-break galaxies previously identified over the eXtreme Deep Field and Hubble Ultra-Deep Field parallel fields and the five Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey fields. Our study is distinctive due to (1) the much deeper (∼200 hr) wide-area Spitzer/Infrared Array Camera (IRAC) imaging at 3.6 <jats:italic>μ</jats:italic>m and 4.5 <jats:italic>μ</jats:italic>m from the Great Observatories Origins Deep Survey Re-ionization Era Wide-area Treasury from Spitzer program (GREATS) and (2) consideration of <jats:italic>z</jats:italic> ∼ 6–10 sources over a 3× larger area than those of previous Hubble Space Telescope+Spitzer studies. The Spitzer/IRAC data enable ≥2<jats:italic>σ</jats:italic> rest-frame optical detections for an unprecedented 50% of galaxies down to a stellar mass limit of <jats:inline-formula> <jats:tex-math> <?CDATA $\sim {10}^{8}{{ \mathcal M }}_{\odot }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>∼</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>8</mml:mn> </mml:mrow> </mml:msup> <mml:msub> <mml:mrow> <mml:mi mathvariant="italic"></mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac1bb6ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> across all redshifts. Schechter fits to our volume densities suggest a combined evolution in the characteristic mass <jats:inline-formula> <jats:tex-math> <?CDATA ${{ \mathcal M }}^{* }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:mi mathvariant="italic"></mml:mi> </mml:mrow> <mml:mrow> <mml:mo>*</mml:mo> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac1bb6ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> and normalization factor <jats:italic>ϕ</jats:italic> <jats:sup>*</jats:sup> between <jats:italic>z</jats:italic> ∼ 6 and <jats:italic>z</jats:italic> ∼ 8. The stellar mass density (SMD) increases by ∼1000× in the ∼500 Myr between <jats:italic>z</jats:italic> ∼ 10 and <jats:italic>z</jats:italic> ∼ 6, with indications of a steeper evolution between <jats:italic>z</jats:italic> ∼ 10 and <jats:italic>z</jats:italic> ∼ 8, similar to the previously reported trend of the star formation rate density. Strikingly, abundance matching to the Bolshoi–Planck simulation indicates halo mass densities evolving at approximately the same rate as the SMD between <jats:italic>z</jats:italic> ∼ 10 and <jats:italic>z</jats:italic> ∼ 4. Our results show that the stellar-to-halo mass ratios, a proxy for the star formation efficiency, do not change significantly over the huge stellar mass buildup occurred from <jats:italic>z</jats:italic> ∼ 10 to <jats:italic>z</jats:italic> ∼ 6, indicating that the assembly of stellar mass closely mirrors the buildup in halo mass in the first ∼1 Gyr of cosmic history. The James Webb Space Telescope is poised to extend these results into the “first galaxy” epoch at <jats:italic>z</jats:italic> ≳ 10.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Images of the solar corona by extreme-ultraviolet telescopes reveal elegant arches of glowing plasma that trace the corona’s magnetic field. Typically, these loops are preferentially illuminated segments of an arcade of vaulted field lines and such loops are often observed to sway in response to nearby solar flares. A flurry of observational and theoretical effort has been devoted to the exploitation of these oscillations with the grand hope that seismic techniques might be used as probes of the strength and structure of the corona’s magnetic field. The commonly accepted viewpoint is that each visible loop oscillates as an independent entity and acts as a one-dimensional wave cavity for magnetohydrodynamic kink waves. We argue that for many events, this generally accepted model for the wave cavity is fundamentally flawed. In particular, the 3D magnetic arcade in which the bright loop resides participates in the oscillation. Thus, the true wave cavity is larger than the individual loop and inherently multidimensional. We derive the skin depth of the near-field response for an oscillating loop and demonstrate that most loops are too close to other magnetic structures to oscillate in isolation. Further, we present a simple model of a loop embedded within an arcade and explore how the eigenmodes of the arcade and the eigenmodes of the loop become coupled. In particular, we discuss how distinguishing between these two types of modes can be difficult when the motions within the arcade are often invisible.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the discovery of 32 new double periodic variables (DPVs) located toward the Galactic bulge. We found these objects among the nearly half a million binary stars published by the Optical Gravitational Lensing Experiment project. With this discovery, we increase the number of known DPVs in the Milky Way by a factor of 2. The new set of DPVs contains 31 eclipsing binaries and one ellipsoidal variable star. The orbital periods cover the range from 1.6 to 26 days, while long periods are detected between 47 and 1144 days. Our analysis confirms a known correlation between orbital and long periods that is also observed in similar systems in the Magellanic Clouds.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the first results of our ongoing project conducting simultaneous multiwavelength observations of flares on nearby active M dwarfs. We acquired data of the nearby dM3.5e star EV Lac using five different observatories: NASA’s Transiting Exoplanet Survey Satellite (TESS), NASA’s Neil Gehrels Swift Observatory (Swift), NASA’s Neutron Interior Composition Explorer (NICER), the University of Hawaii 2.2-meter telescope (UH88), and the Las Cumbres Observatory Global Telescope (LCOGT) Network. During the ∼25 days of TESS observations, we acquired three simultaneous UV/X-ray observations using Swift that total ∼18 ks, 21 simultaneous epochs totaling ∼98 ks of X-ray data using NICER, one observation (∼3 hr) with UH88, and one observation (∼3 hr) with LCOGT. We identified 56 flares in the TESS light curve with estimated energies in the range log <jats:italic>E</jats:italic> <jats:sub>T</jats:sub> (erg) = (30.5–33.2), nine flares in the Swift UVM2 light curve with estimated energies in the range log <jats:italic>E</jats:italic> <jats:sub>UV</jats:sub> (erg) = (29.3–31.1), 14 flares in the NICER light curve with estimated minimum energies in the range log <jats:italic>E</jats:italic> <jats:sub> <jats:italic>N</jats:italic> </jats:sub> (erg) = (30.5–32.3), and 1 flare in the LCOGT light curve with log <jats:italic>E</jats:italic> <jats:sub> <jats:italic>L</jats:italic> </jats:sub> (erg) = 31.6. We find that the flare frequency distributions (FFDs) of TESS and NICER flares have comparable slopes, <jats:italic>β</jats:italic> <jats:sub> <jats:italic>T</jats:italic> </jats:sub> = −0.67 ± 0.09 and <jats:italic>β</jats:italic> <jats:sub> <jats:italic>N</jats:italic> </jats:sub> = − 0.65 ± 0.19, and the FFD of UVOT flares has a shallower slope (<jats:italic>β</jats:italic> <jats:sub> <jats:italic>U</jats:italic> </jats:sub> = −0.38 ± 0.13). Furthermore, we do not find conclusive evidence for either the first ionization potential (FIP) or the inverse FIP effect during coronal flares on EV Lac.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Ultra-high-energy (UHE) cosmic rays (CRs) of energies ∼(10<jats:sup>18</jats:sup>–10<jats:sup>20</jats:sup>) eV, accelerated in violent astrophysical environments, interact with cosmic background radiation fields via photo-hadronic processes, leading to strong attenuation. Typically, the Universe would become “opaque” to UHE CRs after several tens of megaparsecs, setting the boundary of the Greisen–Zatsepin–Kuz’min (GZK) horizon. In this work, we investigate the contribution of sources beyond the conventional GZK horizon to the UHE CR flux observed on Earth, when photospallation of the heavy nuclear CRs is taken into account. We demonstrate that this contribution is substantial, despite the strong attenuation of UHE CRs. A significant consequence is the emergence of an isotropic background component in the observed flux of UHE CRs, coexisting with the anisotropic foreground component that is associated with nearby sources. Multi-particle CR horizons, which evolve over redshift, are determined by the CR nuclear composition. Thus, they are dependent on the source populations and source evolutionary histories.</jats:p>