Sazuna/UAT_keywords huggingface dataset:
Probability Distribution Functions of Sunspot Magnetic Flux. We investigated the probability distributions of sunspot area and magnetic flux by using data from the Royal Greenwich Observatory and USAF/NOAA. We constructed a sample of 2995 regions with maximum-development areas ≥500 MSH (millionths of solar hemisphere), covering 146.7 yr (1874-2020). The data were fitted by a power-law distribution and four two-parameter distributions (tapered-power-law, gamma, lognormal, and Weibull distributions). The power-law model was unfavorable compared to the four models in terms of AIC, and was not acceptable according to the classical Kolmogorov-Smirnov test. The lognormal and Weibull distributions were excluded because their behavior extended to smaller regions (S ≪ 500 MSH) do not connect to previously published results. Therefore, our choices were tapered-power-law and gamma distributions. The power-law portion of the tapered-power-law and gamma distributions was found to have a power exponent of 1.35-1.9. Due to the exponential falloff of these distributions, the expected frequencies of large sunspots are low. The largest sunspot group observed had an area of 6132 MSH, and the frequency of sunspots larger than 104 MSH was estimated to be every 3-8 × 104 yr. We also estimated the distributions of the Sun-as-a-star total sunspot areas. The largest total area covered by sunspots on record was 1.67% of the visible disk, and can be up to 2.7% by artificially increasing the lifetimes of large sunspots in an area evolution model. These values are still smaller than those found on active Sun-like stars.

Keywords: Starspots, Solar photosphere, Sunspots, Solar magnetic fields, Solar activity
The Three Regimes of Atmospheric Evaporation for Super-Earths and Sub-Neptunes. A significant fraction of super-Earths and sub-Neptunes are thought to experience an extreme loss of volatiles because of atmospheric evaporation in the early stages of their life. Though the mechanisms behind the extreme mass loss are not fully understood, two contenders have been widely discussed: photoevaporation from X-ray and ultraviolet irradiation and core-powered mass loss. Here, it is shown that both mechanisms occur, but with different timescales, and that atmospheric loss can take place over three regimes. In the first regime, a planet has very high internal temperatures arising from its high-energy formation processes. These high temperatures give rise to a fully convecting atmosphere that efficiently loses mass without much internal cooling. The second regime applies to planets with lower internal temperatures, so a radiative region forms, but the photosphere still remains outside the Bondi radius. Hence, mass loss continues to depend only on the internal temperatures. Planets with the lowest internal temperatures are in the third regime, when the photosphere forms below the Bondi radius and mass is lost primarily because of X-ray and ultraviolet irradiation. This paper provides the first unifying framework for modeling atmospheric evaporation through the life span of a planet.

Keywords: Super Earths, Exoplanet evolution, Star-planet interactions, Mini Neptunes, Planetary interior, Exoplanet atmospheres
Light Curves and Event Rates of Axion Instability Supernovae. It was recently proposed that exotic particles can trigger a new stellar instability that is analogous to the e - e + pair instability if they are produced and reach equilibrium in the stellar plasma. In this study, we construct axion instability supernova (AISN) models caused by the new instability to predict their observational signatures. We focus on heavy axion-like particles (ALPs) with masses of ~400 keV-2 MeV and coupling with photons of g  a γ  ~ 10-5 GeV-1. It is found that the 56Ni mass and the explosion energy are significantly increased by ALPs for a fixed stellar mass. As a result, the peak times of the light curves of AISNe occur earlier than those of standard pair-instability supernovae by 10-20 days when the ALP mass is equal to the electron mass. Also, the event rate of AISNe is 1.7-2.6 times higher than that of pair-instability supernovae, depending on the high mass cutoff of the initial mass function.

Keywords: Supernovae, Particle astrophysics, Stellar evolution
The Late Afterglow of GW170817/GRB 170817A: A Large Viewing Angle and the Shift of the Hubble Constant to a Value More Consistent with the Local Measurements. The multimessenger data of neutron star merger events are promising for constraining the Hubble constant. So far, GW170817 is still the unique gravitational wave event with multiwavelength electromagnetic counterparts. In particular, its radio and X-ray emission have been measured in the past ~3-5 yr. In this work, we fit the long-lasting X-ray, optical, and radio afterglow light curves of GW170817/GRB 170817A, including the forward shock radiation from both the decelerating relativistic gamma-ray burst outflow and the subrelativistic kilonova outflow (though whether the second component contributes significantly is still uncertain), and find out a relatively large viewing angle (~0.5 rad). Such a viewing angle has been taken as a prior in the gravitational wave data analysis, and the degeneracy between the viewing angle and the luminosity distance is broken. Finally, we have a Hubble constant ${H}_{0}={72.57}_{-4.17}^{+4.09}\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1}$ , which is more consistent with that obtained by other local measurements. If rather similar values are inferred from multimessenger data of future neutron star merger events, it will provide critical support to the existence of the Hubble tension.

Keywords: Hubble constant, Gamma-ray bursts, Gravitational wave astronomy
Energy Dependence of the Line Ratio I(233.9 Å)/I(243.8 Å) in Fe xv Observed with an Electron Beam Ion Trap. We present the energy dependence of the intensity ratio between the 3s3p 3 P 2-3s3d 3 D 3 transition at 233.9 Å and the 3s3p 1 P 1-3s3d 1 D 2 transition at 243.8 Å in Fe XV studied with an electron beam ion trap over an energy range that spans resonance excitation regions. Clear resonance structures are observed in the electron energy range of 400-600 eV. The energy dependence obtained in the experiment is compared with a collisional-radiative model calculation, including resonance excitations, and overall agreement is found. It is shown that the ratio strongly reflects the population of the 3s3p 3 P 2 metastable state, which is the lower state of the 233.9 Å transition.

Keywords: Solar atmosphere, Solar flares, Solar ultraviolet emission, Solar extreme ultraviolet emission, Solar corona, Solar transition region, Stellar atmospheres
High-resolution Spectra of Supernova Remnants in M83. In order to better characterize the rich supernova remnant (SNR) population of M83 (NGC 5236), we have obtained high-resolution (~85 km s-1) spectra of 119 of the SNRs and SNR candidates in M83 with Gemini/GMOS, as well as new spectra of the young SNRs B12-174a and SN 1957D. Most of the SNRs and SNR candidates have [S II]:Hα ratios that exceed 0.4. Combining these results with earlier studies we have carried out with MUSE and at lower spectroscopic resolution with GMOS, we have confirmed a total of 238 emission nebulae to be SNRs on the basis of their [S II]:Hα ratios, about half of which have emission lines that show velocity broadening greater than 100 km s-1, providing a kinematic confirmation that they are SNRs and not H II regions. Looking at the entire sample, we find a strong correlation between velocity widths and the line ratios of [O I] λ6300:Hα, [N II] λ6584:Hα, and [S II] λλ6716, 6731:Hα. The density-sensitive [S II] λ6716:λ6731 line ratio is strongly correlated with SNR diameter, but not with the velocity width. We discuss these results in the context of previously published shock models.

Keywords: Supernova remnants, Interstellar medium, Nebulae
Electrostatic Plasma Wave Excitations at the Interplanetary Shocks. Over the last few decades, different types of plasma waves (e.g., the ion acoustic waves (IAWs), electrostatic solitary waves, upper/lower hybrid waves, and Langmuir waves) have been observed in the upstream, downstream, and ramp regions of the collisionless interplanetary (IP) shocks. These waves may appear as short-duration (only a few milliseconds at 1 au) electric field signatures in the in-situ measurements, with typical frequencies of ~1-10 kHz. A number of IAW features at the IP shocks seem to be unexplained by kinetic models and require a new modeling effort. Thus, this paper is dedicated to bridging this gap in understanding. In this paper, we model the linear IAWs inside the shock ramp by devising a novel linearization method for the two-fluid magnetohydrodynamic equations with spatially dependent shock parameters. It is found that, for parallel propagating waves, the linear dispersion relation leads to a finite growth rate, which is dependent on the shock density compression ratio, as Wind data suggest. Further analysis reveals that the wave frequency grows towards the downstream region within the shock ramp, and the wave growth rate is independent of the electron-to-ion temperature ratio, as Magnetospheric Multiscale (MMS) in-situ measurements suggest, and is uniform within the shock ramp. Thus, this study helps in understanding the characteristics of the IAWs at the collisionless IP shocks.

Keywords: Interplanetary shocks
Statistical Analysis of Lunar 1 Hz Waves Using ARTEMIS Observations. Like 1 Hz waves occurring in the upstream of various celestial bodies in the solar system, 1 Hz narrowband whistler-mode waves are often observed around the Moon. However, wave properties have not been thoroughly investigated, which makes it difficult to proclaim the generation mechanism of the waves. Using 5.5 yr wave data from ARTEMIS, we perform a detailed investigation of 1 Hz waves in the near-lunar space. The amplitude of lunar 1 Hz waves is generally 0.05-0.1 nT. In the geocentric solar ecliptic coordinates, the waves show no significant regional differentiation pattern but show an absence inside the magnetosphere. Correspondingly, in the selenocentric solar ecliptic coordinates, the waves can occur extensively at ~1.1-12 RL, while few events are observed in the lunar wake due to a lack of interaction with the solar wind. Furthermore, the wave distributions exhibit modest day-night and dawn-dusk asymmetries but less apparent north-south asymmetry. Compared with the nightside, more intense waves with lower peak wave frequency are present on the dayside. The preferential distribution of 1 Hz waves exhibits a moderate correlation with strong magnetic anomalies. The waves propagate primarily at wave normal angles &lt;60° with an ellipticity of [-0.8, -0.3]. For stronger wave amplitudes and lower latitudes, 1 Hz waves generally have smaller wave normal angles and become more left-hand circularly polarized. Owing to the unique interaction between the Moon and solar wind, our statistical results might provide new insights into the generation mechanism(s) of 1 Hz waves in planetary plasma environments and promote the understanding of lunar plasma dynamics.

Keywords: Space plasmas, Shocks, Solar wind, Lunar science
Cool, Luminous, and Highly Variable Stars in the Magellanic Clouds. II. Spectroscopic and Environmental Analysis of Thorne-Żytkow Object and Super-AGB Star Candidates. In previous work, we identified a population of 38 cool and luminous variable stars in the Magellanic Clouds and examined 11 in detail in order to classify them as either Thorne-Żytkow objects (TŻOs; red supergiants with a neutron star cores) or super-asymptotic giant branch (sAGB) stars (the most massive stars that will not undergo core collapse). This population includes HV 2112, a peculiar star previously considered in other works to be either a TŻO or high-mass asymptotic giant branch (AGB) star. Here we continue this investigation, using the kinematic and radio environments and local star formation history of these stars to place constraints on the age of the progenitor systems and the presence of past supernovae. These stars are not associated with regions of recent star formation, and we find no evidence of past supernovae at their locations. Finally, we also assess the presence of heavy elements and lithium in their spectra compared to red supergiants. We find strong absorption in Li and s-process elements compared to RSGs in most of the sample, consistent with sAGB nucleosynthesis, while HV 2112 shows additional strong lines associated with TŻO nucleosynthesis. Coupled with our previous mass estimates, the results are consistent with the stars being massive (~4-6.5 M ⊙) or sAGB (~6.5-12 M ⊙) stars in the thermally pulsing phase, providing crucial observations of the transition between low- and high-mass stellar populations. HV 2112 is more ambiguous; it could either be a maximally massive sAGB star, or a TŻO if the minimum mass for stability extends down to ≲13 M ⊙.

Keywords: Stellar kinematics, Massive stars, Asymptotic giant branch stars, Spectroscopy, Lithium stars, Magellanic Clouds, Chemically peculiar stars
DeepZipper. II. Searching for Lensed Supernovae in Dark Energy Survey Data with Deep Learning. Gravitationally lensed supernovae (LSNe) are important probes of cosmic expansion, but they remain rare and difficult to find. Current cosmic surveys likely contain 5-10 LSNe in total while next-generation experiments are expected to contain several hundred to a few thousand of these systems. We search for these systems in observed Dark Energy Survey (DES) five year SN fields-10 3 sq. deg. regions of sky imaged in the griz bands approximately every six nights over five years. To perform the search, we utilize the DeepZipper approach: a multi-branch deep learning architecture trained on image-level simulations of LSNe that simultaneously learns spatial and temporal relationships from time series of images. We find that our method obtains an LSN recall of 61.13% and a false-positive rate of 0.02% on the DES SN field data. DeepZipper selected 2245 candidates from a magnitude-limited (m  i  &lt; 22.5) catalog of 3,459,186 systems. We employ human visual inspection to review systems selected by the network and find three candidate LSNe in the DES SN fields.

Keywords: Strong gravitational lensing, Supernovae
Deep X-Ray and Radio Observations of the First Outburst of the Young Magnetar Swift J1818.0-1607. Swift J1818.0-1607 is a radio-loud magnetar with a spin period of 1.36 s and a dipolar magnetic field strength of B ~ 3 × 1014 G, which is very young compared to the Galactic pulsar population. We report here on the long-term X-ray monitoring campaign of this young magnetar using XMM-Newton, NuSTAR, and Swift from the activation of its first outburst in 2020 March until 2021 October, as well as INTEGRAL upper limits on its hard X-ray emission. The 1-10 keV magnetar spectrum is well modeled by an absorbed blackbody with a temperature of kT BB ~ 1.1 keV and apparent reduction in the radius of the emitting region from ~0.6 to ~0.2 km. We also confirm the bright diffuse X-ray emission around the source extending between ~50″ and ~110″. A timing analysis revealed large torque variability, with an average spin-down rate $\dot{\nu }\,\sim $ -2.3 × 10-11 Hz2 that appears to decrease in magnitude over time. We also observed Swift J1818.0-1607 with the Karl G. Jansky Very Large Array on 2021 March 22. We detected the radio counterpart to Swift J1818 measuring a flux density of S  v  = 4.38 ± 0.05 mJy at 3 GHz and a half-ringlike structure of bright diffuse radio emission located at ~90″ to the west of the magnetar. We tentatively suggest that the diffuse X-ray emission is due to a dust-scattering halo and that the radio structure may be associated with the supernova remnant of this young pulsar, based on its morphology.

Keywords: Neutron stars, Magnetars
Transport of Cosmic-Ray Electrons from 1 au to the Sun. Gamma rays are produced by cosmic-ray (CR) protons interacting with the particles at the solar photosphere and by CR electrons and positrons (CRes) via inverse Compton scattering of solar photons. The former comes from the solar disk while the latter extends beyond the disk. Evaluation of these emissions requires the flux and spectrum of CRs in the vicinity of the Sun, while most observations provide flux and spectra near the Earth, at around 1 au from the Sun. Past estimates of the quiet Sun gamma-ray emission use phenomenological modulation procedures to estimate spectra near the Sun. We show that CRe transport in the inner heliosphere requires a kinetic approach and use a novel approximation to determine the variation of CRe flux and spectrum from 1 au to the Sun including the effects of (1) the structure of the large-scale magnetic field, (2) small scale turbulence in the solar wind from several in situ measurements, in particular, those by Parker Solar Probe that extend this information to 0.1 au, and (3) most importantly, energy losses due to synchrotron and inverse Compton processes. We present results on the flux and spectrum variation of CRes from 1 au to the Sun for several transport models. In forthcoming papers we will use these results for a more accurate estimate of quiet Sun inverse Compton gamma-ray spectra, and, for the first time, the spectra of extreme ultraviolet to hard X-ray photons produced by synchrotron emission. These can be compared with the quiet Sun gamma-ray observation by the Fermi and X-ray upper limits set by RHESSI.

Keywords: Interplanetary turbulence, Solar wind, Cosmic rays
Investigating Loop Quantum Gravity with Event Horizon Telescope Observations of the Effects of Rotating Black Holes. A mathematically consistent rotating black hole model in loop quantum gravity (LQG) is yet lacking. The scarcity of rotating black hole solutions in LQG substantially hampers the development of testing LQG from observations, e.g., from the Event Horizon Telescope (EHT) observations. The EHT observation revealed event horizon-scale images of the supermassive black holes Sgr A* and M87*. The EHT results are consistent with the shadow of a Kerr black hole of general relativity. We present LQG-motivated rotating black hole (LMRBH) spacetimes, which are regular everywhere and asymptotically encompass the Kerr black hole as a particular case. The LMRBH metric describes a multi-horizon black hole in the sense that it can admit up to three horizons, such that an extremal LMRBH, unlike the Kerr black hole, refers to a black hole with angular momentum a &gt; M. The metric, depending on the parameters, describes (1) black holes with only one horizon (BH-I), (2) black holes with an event horizon and a Cauchy horizon (BH-II), (3) black holes with three horizons (BH-III), or (4) no-horizon spacetime, which we show is almost ruled out by EHT observations. We constrain the LQG parameter with the aid of the EHT shadow observational results of M87* and Sgr A*, respectively, for inclination angles of 17° and 50°. In particular, the VLTI bound for Sgr A*, δ ∈ (-0.17, 0.01), constrains the parameters (a, l) such that for 0 &lt; l ≤ 0.347851M (l ≤ 2 × 106 km), the allowed range of a is (0, 1.0307M). Together with the EHT bounds of Sgr A* and M87* observables, our analysis concludes that a substantial part of BH-I and BH-II parameter space agrees with the EHT results of M87* and Sgr A*. While the EHT M87* results totally rule out BH-III, but not that by Sgr A*.

Keywords: Black hole physics, Photon sphere, Event horizons
The R-Process Alliance: Chemodynamically Tagged Groups. II. An Extended Sample of Halo r-process-enhanced Stars. Orbital characteristics based on Gaia Early Data Release 3 astrometric parameters are analyzed for ~1700 r-process-enhanced (RPE; [Eu/Fe] &gt; +0.3) metal-poor stars ([Fe/H] ≤ -0.8) compiled from the R-Process Alliance, the GALactic Archaeology with HERMES (GALAH) DR3 survey, and additional literature sources. We find dynamical clusters of these stars based on their orbital energies and cylindrical actions using the HDBSCAN unsupervised learning algorithm. We identify 36 chemodynamically tagged groups (CDTGs) containing between five and 22 members; 17 CDTGs have at least 10 member stars. Previously known Milky Way (MW) substructures such as Gaia-Sausage-Enceladus, the splashed disk, the metal-weak thick disk, the Helmi stream, LMS-1 (Wukong), and Thamnos are reidentified. Associations with MW globular clusters are determined for seven CDTGs; no recognized MW dwarf galaxy satellites were associated with any of our CDTGs. Previously identified dynamical groups are also associated with our CDTGs, adding structural determination information and possible new identifications. Carbon-enhanced metal-poor RPE (CEMP-r) stars are identified among the targets; we assign these to morphological groups in a Yoon-Beers A(C) c  versus [Fe/H] diagram. Our results confirm previous dynamical analyses that showed RPE stars in CDTGs share common chemical histories, influenced by their birth environments.

Keywords: Milky Way formation, Galactic archaeology, Galaxy dynamics, Milky Way dynamics, R-process, Milky Way stellar halo, Milky Way evolution
Solar Orbiter and SDO Observations, and a Bifrost Magnetohydrodynamic Simulation of Small-scale Coronal Jets. We report high-resolution, high-cadence observations of five small-scale coronal jets in an on-disk quiet Sun region observed with Solar Orbiter's EUI/HRIEUV in 174 Å. We combine the HRIEUV images with the EUV images of SDO/AIA and investigate the magnetic setting of the jets using coaligned line-of-sight magnetograms from SDO/HMI. The HRIEUV jets are miniature versions of typical coronal jets as they show narrow collimated spires with a base brightening. Three out of five jets result from a detectable minifilament eruption following flux cancelation at the neutral line under the minifilament, analogous to coronal jets. To better understand the physics of jets, we also analyze five small-scale jets from a high-resolution Bifrost MHD simulation in synthetic Fe IX/Fe X emissions. The jets in the simulation reside above neutral lines and four out of five jets are triggered by magnetic flux cancelation. The temperature maps show evidence of cool gas in the same four jets. Our simulation also shows the signatures of opposite Doppler shifts (of the order of ±10 s of km s-1) in the jet spire, which is evidence of untwisting motion of the magnetic field in the jet spire. The average jet duration, spire length, base width, and speed in our observations (and in synthetic Fe IX/Fe X images) are 6.5 ± 4.0 min (9.0 ± 4.0 minutes), 6050 ± 2900 km (6500 ± 6500 km), 2200 ± 850 km, (3900 ± 2100 km), and 60 ± 8 km s-1 (42 ± 20 km s-1), respectively. Our observation and simulation results provide a unified picture of small-scale solar coronal jets driven by magnetic reconnection accompanying flux cancelation. This picture also aligns well with the most recent reports of the formation and eruption mechanisms of larger coronal jets.

Keywords: Jets, Solar magnetic reconnection, Solar corona, Solar magnetic fields, Solar chromosphere