Sazuna/UAT_keywords huggingface dataset:
Comparison of the Composition of ICMEs from Active Regions and Quiet-Sun Regions. The composition of interplanetary coronal mass ejections (ICMEs), including the ionic charge states and elemental abundances of heavy elements, is tightly correlated with their source regions and eruption processes. This can help in analyzing the eruption mechanisms and plasma origins of CMEs, and deepen our understanding of energetic solar activities. The active regions and quiet-Sun regions have different physical properties; thus, from a statistical point of view, ICMEs originating from the two types of regions should exhibit different compositional characteristics. To demonstrate the differences comprehensively, we conduct survey studies on the ionic charge states of five elements (Mg, Fe, Si, C, and O) and the relative abundances of six elements (Mg/O, Fe/O, Si/O, C/O, Ne/O, and He/O) within ICMEs from 1998 February to 2011 August using data from the Advanced Composition Explorer. The results show that ICMEs from active regions have higher ionic charge states and relative abundances than those from quiet-Sun regions. For the active-region ICMEs, we further analyze the relations between their composition and flare class, and find a positive relationship between them, i.e., the higher the classes of the associated flares, the larger the means of the ionic charge states and relative abundances (except the C/O) within ICMEs. As more (less) fractions of ICMEs originate from active regions around the solar maximum (minimum), and active-region ICMEs usually are associated with higher-class flares, our studies might answer why the composition of ICMEs measured near 1 au exhibits a solar cycle dependence.

Keywords: Solar abundances, Solar flares, Solar coronal mass ejections
New Parameters for Star Cluster Dynamics: The Effect of Primordial Binaries and Dark Remnants. By studying the normalized cumulative radial distribution (nCRD) of the stars in the central region of a Monte Carlo-simulated globular cluster, we recently defined three parameters able to pinpoint the stage of internal dynamical evolution reached by the system: A 5 (i.e., the area subtended by the nCRD within 5% of the half-mass radius, r  h ), P 5 (the value of the nCRD at 5% r  h ), and S 2.5 (the slope of the nCRD at 2.5% r  h ). Here we extend the analysis and explore the effects that different fractions (0%, 10%, and 20%) of primordial binaries and stellar mass black holes (BHs) induce on the dynamical history of the system. As expected, the gradual contraction of the cluster becomes milder and core collapse shallower for an increasing binary fraction. Nevertheless, the cluster dynamical evolution is still properly traced by the three parameters. For models with a larger initial retention of stellar mass BHs, the evolution depends on the timescale of their subsequent dynamical ejection. An early dynamical ejection of BHs results in a long-term evolution of the three parameters similar to that found in systems without initial BH retention. Conversely, in the model that retains a large number of BHs for an extended time (slow dynamical ejection of BHs), the system is characterized by a less concentrated structure and by the lack of significant temporal evolution of the three parameters. The lower values of the three parameters found in this case might be used to indirectly infer the possible presence of BHs in the cluster.

Keywords: Globular star clusters, Stellar dynamics
Boundary Layers of Circumplanetary Disks around Spinning Planets. I. Effects of Rossby Waves. Gas giant planets are believed to accrete from their circumplanetary disks (CPDs). The CPDs usually involve accretion through the boundary layer (BL) in the vicinity of planets. Prior studies have concentrated on the BL of nonspinning planets. We investigate the influence of planetary spin on the wave behaviors within the BL. The rotation profile in such BLs would show a sharp transition from the rigid rotation to the Keplerian rotation. We examine the angular momentum transport in these BLs in terms of linear perturbation analysis. We find that the global inertia-acoustic mode associated with spinning planets would give rise to the inflow of angular momentum and the accretion of gas. In this work, we identify a new kind of global mode, namely the Rossby mode. The Rossby mode can lead to the outflow of angular momentum and the decretion of gas from a spinning planet. The Rossby mode provides a negative feedback that regulates the planetary spin and mass. We compare the growth rate of the two modes as a function of the width of BL, the Mach number, and the spin rate of planets. Our results reveal the underlying hydrodynamic mechanism of terminal spins and asymptotic mass of the giant planets.

Keywords: Exoplanet dynamics, Accretion, Planetary-disk interactions, Exoplanet atmospheric dynamics, Exoplanet formation, Planet formation
Polarized Signatures of a Habitable World: Comparing Models of an Exoplanet Earth with Visible and Near-infrared Earthshine Spectra. In the JWST, Extremely Large Telescopes, and LUVOIR era, we expect to characterize a number of potentially habitable Earth-like exoplanets. However, the characterization of these worlds depends crucially on the accuracy of theoretical models. Validating these models against observations of planets with known properties will be key for the future characterization of terrestrial exoplanets. Due to its sensitivity to the micro- and macro-physical properties of an atmosphere, polarimetry will be an important tool that, in tandem with traditional flux-only observations, will enhance the capabilities of characterizing Earth-like planets. In this paper we benchmark two different polarization-enabled radiative-transfer codes against each other and against unique linear spectropolarimetric observations of the earthshine that cover wavelengths from ~0.4 to ~2.3 μm. We find that while the results from the two codes generally agree with each other, there is a phase dependency between the compared models. Additionally, with our current assumptions, the models from both codes underestimate the level of polarization of the earthshine. We also report an interesting discrepancy between our models and the observed 1.27 μm O2 feature in the earthshine, and provide an analysis of potential methods for matching this feature. Our results suggest that only having access to the 1.27 μm O2 feature coupled with a lack of observations of the O2 A and B bands could result in a mischaracterization of an Earth-like atmosphere. Providing these assessments is vital to aid the community in the search for life beyond the solar system.

Keywords: Spectropolarimetry, Exoplanets, Planetary atmospheres, Radiative transfer, Polarimetry, Habitable planets
The Messy Nature of Fiber Spectra: Star-Quasar Pairs Masquerading as Dual Type 1 AGNs. Theoretical studies predict that the most significant growth of supermassive black holes (SMBHs) occurs in late-stage mergers, coinciding with the manifestation of dual active galactic nuclei (AGNs), and both major and minor mergers are expected to be important for dual AGN growth. In fact, dual AGNs in minor mergers should be signposts for efficient minor-merger-induced SMBH growth for both the more and less massive progenitor. We identified two candidate dual AGNs residing in apparent minor mergers with mass ratios of ~1:7 and ~1:30. Sloan Digital Sky Survey (SDSS) fiber spectra show broad and narrow emission lines in the primary nuclei of each merger while only a narrow [O III] emission line and a broad and prominent Hα/[N II] complex is observed in the secondary nuclei. The FWHMs of the broad Hα lines in the primary and secondary nuclei are inconsistent in each merger, suggesting that each nucleus in each merger hosts a Type 1 AGN. However, spatially resolved Large Binocular Telescope optical spectroscopy reveals rest-frame stellar absorption features, indicating the secondary sources are foreground stars and that the previously detected broad lines are likely the result of fiber spillover effects induced by the atmospheric seeing at the time of the SDSS observations. This study demonstrates for the first time that optical spectroscopic searches for Type 1/Type 1 pairs similarly suffer from fiber spillover effects as has been observed previously for Seyfert 2 dual AGN candidates. The presence of foreground stars may not have been clear if an instrument with more limited wavelength range or limited sensitivity had been used.

Keywords: Active galaxies, Active galactic nuclei
Low-frequency Waves Due to Newborn Interstellar Pickup Ions Observed from 43 to 47 au by the Voyager 1 Spacecraft. Interstellar neutral atoms enter the heliosphere at a relatively slow speed corresponding to the motion of the Sun through the local interstellar medium, which is approximately 25 km s-1. Neutral hydrogen atoms enter from the approximate location of the Voyager spacecraft and are eventually ionized primarily by collision with thermal solar wind ions. An earlier analysis by Hollick et al. examined low-frequency magnetic waves observed by the Voyager spacecraft from launch through 1990 that are thought to arise from the scattering of newborn interstellar pickup H+ and He+. We report an analysis of Voyager 1 observations in 1991, which is the last year of high-resolution magnetic field data that are publicly available, and find 70 examples of low-frequency waves with the characteristics that suggest excitation by pickup H+ and 10 examples of waves consistent with excitation by pickup He+. We find a particularly dense cluster of observations at the tail end of what is thought to be a Merged Interaction Region (MIR) that was previously studied by Burlaga &amp; Ness using Voyager 2 observations. This is not unexpected if the MIR is followed by a large rarefaction region, as they tend to be regions of reduced turbulence levels that permit the growth of the waves over the long time periods that are generally required of this instability.

Keywords: Interplanetary turbulence, Pickup ions, Solar wind, Interplanetary magnetic fields
A Unified Model for Bipolar Outflows from Young Stars: Apparent Magnetic Jet Acceleration. We explore a new, efficient mechanism that can power toroidally magnetized jets up to two to three times their original terminal velocity after they enter a self-similar phase of magnetic acceleration. Underneath the elongated outflow lobe formed by a magnetized bubble, a wide-angle free wind, through the interplay with its ambient toroid, is compressed and accelerated around its axial jet. The extremely magnetic bubble can inflate over its original size, depending on the initial Alfvén Mach number M A of the launched flow. The shape-independent slope ∂v  r /∂r = 2/3t is a salient feature of the self-similarity in the acceleration phase. Peculiar kinematic signatures are observable in the PV diagrams and can combine with other morphological signatures as probes for density-collimated jets arising in toroidally dominated magnetized winds. The apparent second acceleration is powered by the decrease of the toroidal magnetic field but operates far beyond the scales of the primary magnetocentrifugal launch region and the free asymptotic terminal state. Rich implications may connect the jets arising from the youngest protostellar outflows such as HH 211 and HH 212 and similar systems with parsec-scale jets across the mass and evolutionary spectra.

Keywords: Magnetohydrodynamics, Stellar-interstellar interactions, Jets, Radio jets, Stellar wind bubbles, Stellar jets, Relativistic jets, Stellar winds, Star formation, Astronomical simulations, Magnetohydrodynamical simulations
JWST Low-resolution MIRI Spectral Observations of SN 2021aefx: High-density Burning in a Type Ia Supernova. We present a JWST/MIRI low-resolution mid-infrared (MIR) spectroscopic observation of the normal Type Ia supernova (SN Ia) SN 2021aefx at +323 days past rest-frame B-band maximum light. The spectrum ranges from 4 to 14 μm and shows many unique qualities, including a flat-topped [Ar III] 8.991 μm profile, a strongly tilted [Co III] 11.888 μm feature, and multiple stable Ni lines. These features provide critical information about the physics of the explosion. The observations are compared to synthetic spectra from detailed non-local thermodynamic equilibrium multidimensional models. The results of the best-fitting model are used to identify the components of the spectral blends and provide a quantitative comparison to the explosion physics. Emission line profiles and the presence of electron capture elements are used to constrain the mass of the exploding white dwarf (WD) and the chemical asymmetries in the ejecta. We show that the observations of SN 2021aefx are consistent with an off-center delayed detonation explosion of a near-Chandrasekhar mass (M Ch) WD at a viewing angle of -30° relative to the point of the deflagration to detonation transition. From the strengths of the stable Ni lines, we determine that there is little to no mixing in the central regions of the ejecta. Based on both the presence of stable Ni and the Ar velocity distributions, we obtain a strict lower limit of 1.2 M ⊙ for the initial WD, implying that most sub-M Ch explosions models are not viable models for SN 2021aefx. The analysis here shows the crucial importance of MIR spectra in distinguishing between explosion scenarios for SNe Ia.

Keywords: James Webb Space Telescope, Type Ia supernovae, Supernovae
Resurrection of Type IIL Supernova 2018ivc: Implications for a Binary Evolution Sequence Connecting Hydrogen-rich and Hydrogen-poor Progenitors. Long-term observations of synchrotron emission from supernovae (SNe), covering more than a year after the explosion, provide a unique opportunity to study the poorly understood evolution of massive stars in the final millennium of their lives via changes in the mass-loss rate. Here we present a result of our long-term monitoring of the peculiar Type IIL SN 2018ivc using the Atacama Large Millimeter/submillimeter Array. Following the initial decay, it showed unprecedented rebrightening starting ∼1 yr after the explosion. This is one of the rare examples showing such rebrightening in the synchrotron emission and the first case at millimeter wavelengths. We find it to be in the optically thin regime, unlike the optically thick centimeter emission. As such, we can robustly reconstruct the distribution of the circumstellar matter and thus the mass-loss history in the final ≳1000 yr. We find that the progenitor of SN 2018ivc had experienced a very high mass-loss rate (≳10−3 M ⊙ yr−1) ∼1500 yr before the explosion, which was followed by a moderately high mass-loss rate (≳10−4 M ⊙ yr−1) up until the explosion. From this behavior, we suggest that SN 2018ivc represents an extreme version of a binary evolution toward SNe IIb, which bridges the hydrogen-poor SNe (toward SNe Ib/c, without a hydrogen envelope) and hydrogen-rich SNe (SNe IIP, with a massive envelope).

Keywords: Millimeter astronomy, Circumstellar matter, Non-thermal radiation sources, Supernovae, Radio sources, Stellar evolution
Discovery of an Exceptional Optical Nebulosity in the Suspected Galactic SN Iax Remnant Pa 30 Linked to the Historical Guest Star of 1181 CE. A newly recognized young Galactic supernova (SN) remnant, Pa 30 (G123.1+4.6), centered on a hot central star with a ~16,000 km s-1 wind velocity, has recently been proposed to be the result of a double-degenerate merger leading to an SN Iax event associated with the guest star of 1181 CE. Here we present deep optical [S II] λλ6716,6731 images of Pa 30 that reveal an extraordinary and highly structured nebula 170″ in diameter with dozens of long (5″-20″), radially aligned filaments with a convergence point near the hot central star. Optical spectra of filaments indicate a peak expansion velocity ≃1100 km s-1 with electron densities of ≤100-700 cm-3 and a thick shell-like structure resembling its appearance in 22 μm WISE images. No Hα emission was seen ([S II] λ6716/Hα &gt;5), with the only other line emission detected being faint [Ar III] λ7136, suggesting a S- and Ar-rich but H-poor remnant. The nebula's angular size, estimated 2.3 kpc distance, and 1100 km s-1 expansion velocity are consistent with an explosion date around 1181 CE. The remnant's unusual appearance may be due to the photoionization of wind-driven ejecta due to clump-wind interactions caused by the central star's high-luminosity wind.

Keywords: Supernova remnants, Circumstellar matter, Emission nebulae, Type Ia supernovae, Spectroscopy
A Dwarf Galaxy Debris Stream Associated with Palomar 1 and the Anticenter Stream. We report the discovery of a new stream (dubbed as Yangtze) detected in Gaia Data Release 3. The stream is at a heliocentric distance of ~9.12 kpc and spans nearly 27° by 1.°9 on the sky. The color-magnitude diagram of Yangtze indicates a stellar population of age ~11 Gyr and [M/H] ~ -0.7 dex. It has a number density of about 5.5 stars deg-2 along with a surface brightness of Σ G  ≃ 34.9 mag arcsec-2. The dynamics and metallicity estimate suggest that Yangtze may be closely related to Palomar 1 and the Anticenter Stream.

Keywords: Milky Way stellar halo, Stellar streams
Discovery of the Exceptionally Short Period Ultracool Dwarf Binary LP 413-53AB. We report the detection of large-amplitude, rapid radial velocity (RV) variations and line-splitting in high-resolution Keck/NIRSPEC spectra of the M9 dwarf LP 413-53. We attribute these features to binary motion. Analyzing data spanning 15 yr, we infer a preliminary orbital period of 0.7106156 ± 0.0000002 days, an eccentricity of 0.0088 ± 0.0017, a primary RV semiamplitude of 23.70 ± 0.05 km s-1, and a secondary RV semiamplitude of 28.41 ± 0.06 km s-1, implying a system mass ratio M secondary/M primary = 0.8340 ± 0.0017. These measurements identify LP 413-53 as the shortest-period ultracool binary discovered to date, and one of the smallest separation main-sequence binaries known. The position and velocity of the system rule out previously reported membership in the Hyades Moving Group, and indicate that this is likely a pair of evolved (age ≳1 Gyr), very-low-mass stars. Assuming masses consistent with evolved late-M and L dwarfs, we estimate an orbital separation of 0.0081-0.0084 au or 17-19 stellar radii, and an orbital inclination angle of 24°, making it unlikely that this system exhibits eclipse events. The larger radii of these stars at young ages would have put them near contact at the system's current separation, and we speculate that this system has undergone dynamical evolution, either through orbital angular momentum loss or ejection of a third component followed by tidal circularization. While further observations are needed to fully constrain the orbital and physical parameters of LP 413-53, this ultra-short-period ultracool dwarf binary system serves as a new test bed for formation and dynamical evolution models of very-low-mass multiples.

Keywords: M dwarf stars, High resolution spectroscopy, Close binary stars, Spectroscopic binary stars, Low mass stars
JWST/MIRI Spectroscopy of the Disk of the Young Eruptive Star EX Lup in Quiescence. EX Lup is a low-mass pre-main-sequence star that occasionally shows accretion-related outbursts. Here, we present JWST/MIRI medium-resolution spectroscopy obtained for EX Lup 14 yr after its powerful outburst. EX Lup is now in quiescence and displays a Class II spectrum. We detect a forest of emission lines from molecules previously identified in infrared spectra of classical T Tauri disks: H2O, OH, H2, HCN, C2H2, and CO2. The detection of organic molecules demonstrates that they are back after disappearing during the large outburst. Spectral lines from water and OH are for the first time deblended and will provide a much-improved characterization of their distribution and density in the inner disk. The spectrum also shows broad emission bands from warm, submicron-size amorphous silicate grains at 10 and 18 μm. During the outburst, in 2008, crystalline forsterite grains were annealed in the inner disk within 1 au, but their spectral signatures in the 10 μm silicate band later disappeared. With JWST we rediscovered these crystals via their 19.0, 20.0, and 23.5 μm emission, the strength of which implies that the particles are at ~3 au from the star. This suggests that crystalline grains formed in 2008 were transported outwards and now approach the water snowline, where they may be incorporated into planetesimals. Containing several key tracers of planetesimal and planet formation, EX Lup is an ideal laboratory to study the effects of variable luminosity on the planet-forming material and may provide an explanation for the observed high crystalline fraction in solar system comets.

Keywords: Low mass stars, Eruptive variable stars, Protoplanetary disks, Infrared spectroscopy
Searches for Neutrinos from Large High Altitude Air Shower Observatory Ultra-high-energy γ-Ray Sources Using the IceCube Neutrino Observatory. Galactic PeV cosmic-ray accelerators (PeVatrons) are Galactic sources theorized to accelerate cosmic rays up to PeV in energy. The accelerated cosmic rays are expected to interact hadronically with nearby ambient gas or the interstellar medium, resulting in γ-rays and neutrinos. Recently, the Large High Altitude Air Shower Observatory (LHAASO) identified 12 γ-ray sources with emissions above 100 TeV, making them candidates for PeVatrons. While at these high energies the Klein-Nishina effect exponentially suppresses leptonic emission from Galactic sources, evidence for neutrino emission would unequivocally confirm hadronic acceleration. Here, we present the results of a search for neutrinos from these γ-ray sources and stacking searches testing for excess neutrino emission from all 12 sources as well as their subcatalogs of supernova remnants and pulsar wind nebulae with 11 yr of track events from the IceCube Neutrino Observatory. No significant emissions were found. Based on the resulting limits, we place constraints on the fraction of γ-ray flux originating from the hadronic processes in the Crab Nebula and LHAASO J2226+6057.

Keywords: Galactic cosmic rays, Neutrino astronomy, High energy astrophysics
COSMOS2020: Discovery of a Protocluster of Massive Quiescent Galaxies at z = 2.77. Protoclusters of galaxies have been found in the last quarter-century. However, most of them have been found through the overdensity of star-forming galaxies, and there have been no known structures identified by more than two spectroscopically confirmed quiescent galaxies at z &gt; 2.5. In this letter, we report the discovery of an overdense structure of massive quiescent galaxies with the spectroscopic redshift z = 2.77 in the COSMOS field, QO-1000. We first photometrically identify this structure as a 4.2σ overdensity with 14 quiescent galaxies in 7 × 4 pMpc2 from the COSMOS2020 catalog. We then securely confirm the spectroscopic redshifts of four quiescent galaxies by detecting multiple Balmer absorption lines with Keck/MOSFIRE. All the spectroscopically confirmed members are massive ( $\mathrm{log}({M}_{\star }/{M}_{\odot })\gt 11.0$ ) and located in a narrow redshift range (2.76 &lt; z &lt; 2.79). Moreover, three of them are in the 1 × 1 pMpc2 in the transverse direction at the same redshift (z = 2.760-2.763). Such a concentration of four spectroscopically confirmed quiescent galaxies implies that QO-1000 is &gt;68 times denser than the general field. In addition, we confirm that they form a red sequence in the J - K  s  color. This structure's halo mass is estimated as $\mathrm{log}({M}_{\mathrm{halo}}/{M}_{\odot })\gt 13.2$ from its stellar mass. Similar structures found in the IllustrisTNG simulation are expected to evolve into massive galaxy clusters with $\mathrm{log}({M}_{\mathrm{halo}}/{M}_{\odot })\geqslant 14.8$ at z = 0. These results suggest that QO-1000 is a more mature protocluster than the other known protoclusters. It is likely in a transition phase between star-forming protoclusters and quenched galaxy clusters.

Keywords: Quenched galaxies, Galaxy environments, High-redshift galaxy clusters, Galaxy evolution, Galaxy quenching