adsabs/SciX_UAT_keywords huggingface dataset:
Kink Oscillation of a Flux Rope During a Failed Solar Eruption

We report a decaying kink oscillation of a flux rope during a confined eruptive flare, observed off the solar limb by the Solar Dynamics Observatory's Atmospheric Imaging Assembly (AIA), which lacked a detectable white-light coronal mass ejection. The erupting flux rope underwent kinking, rotation, and apparent leg-leg interaction during the event. The oscillations were observed simultaneously in multiple AIA channels at 304, 171, and 193 Å, indicating that multithermal plasma was entrained in the rope. After reaching the overlying loops in the active region, the flux rope exhibited large-amplitude, decaying kink oscillations with an apparent initial amplitude of 30 Mm, a period of about 16 minutes, and a decay time of about 17 minutes. We interpret these oscillations as a fundamental standing kink mode of the flux rope. The oscillation polarization has a clear vertical component, while the departure of the detected waveform from a sinusoidal signal suggests that the oscillation could be circularly or elliptically polarized. The estimated kink speed is 1080 km s-1, corresponding to an Alfvén speed of about 760 km s-1. This speed, together with the estimated electron density in the rope from our differential emission measure analysis, n e ≈ (1.5-2.0) × 109 cm-3, yields a magnetic-field strength of about 15 G. To the best of our knowledge, decaying kink oscillations of a flux rope with nonhorizontal polarization during a confined eruptive flare have not been reported before. These oscillations provide unique opportunities for indirect measurements of the magnetic-field strength in low-coronal flux ropes during failed eruptions.

Keywords: solar active regions; solar x-ray flares; solar magnetic reconnection; solar filaments; solar coronal seismology; solar coronal mass ejections
Do Hα Stokes V Profiles Probe the Chromospheric Magnetic Field? An Observational Perspective

We investigated the diagnostic potential of the Stokes V profile of the Hα line to probe the chromospheric line-of-sight (LOS) magnetic field (B LOS) by comparing the B LOS inferred from the weak field approximation (WFA) with that inferred from the multiline inversions of the CaII 8542 Å, Si I 8536 Å, and Fe I 8538 Å lines using the STiC inversion code. Simultaneous spectropolarimetric observations of a pore in the Ca II 8542 Å and Hα spectral lines obtained from the SPINOR at the Dunn Solar Telescope on 2008 December 4 are used in this study. The WFA was applied on the Stokes I and V profiles of Hα line over three wavelength ranges, viz., around line core (Δλ = ±0.35 Å), line wings (Δλ = [-1.5, -0.6], and [+0.6, +1.5] Å), and full spectral range of the line (Δλ = ± 1.5 Å) to derive the B LOS. We found the maximum B LOS strengths of ~+800 and ~+600 G at $\mathrm{log}{\tau }_{500}$ = -1 and -4.5, respectively, in the pore. The morphological map of the B LOS inferred from the Hα line core is similar to the B LOS map at $\mathrm{log}{\tau }_{500}$ = -4.5 inferred from multiline inversions. The B LOS map inferred from the Hα line wings and full spectral range have a similar morphological structure to the B LOS map inferred at $\mathrm{log}{\tau }_{500}$ = -1. The B LOS estimated from Hα using WFA is weaker by a factor of ≈0.53 than that of inferred from the multiline inversions. * Not yet released.

Keywords: spectropolarimetry; radiative transfer; solar chromosphere; solar magnetic fields
DEEPCR on ACS/WFC: Cosmic-Ray Rejection for HST ACS/WFC Photometry

DEEPCR is a deep-learning-based cosmic-ray rejection algorithm previously demonstrated to be superior to state-of-the-art LACosmic on Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS)/WFC F606W imaging data. In this research note, we present a new DEEPCR model for use on all filters of HST ACS/WFC. We train and test the model with ACS/WFC F435W, F606W, and F814W images, covering the entire spectral range of the ACS optical channel. The global model demonstrates near 100% detection rates of CRs in extragalactic fields and globular clusters and 91% in resolved galaxy fields. We further confirm the global applicability of the model by comparing its performance against single-filter models that were trained simultaneously and by testing the global model on data from another filter which was not previously used for training.

Keywords: astronomy data reduction; convolutional neural networks; classification; neural networks; cosmic rays; hubble space telescope; astronomical detectors
Tests of the Kerr Hypothesis with MAXI J1803-298 Using Different RELXILL_NK Flavors

Iron line spectroscopy has been one of the leading methods not only for measuring the spins of accreting black holes but also for testing fundamental physics. Basing on such a method, we present an analysis of a data set observed simultaneously by NuSTAR and NICER for the black hole binary candidate MAXI J1803-298, which shows prominent relativistic reflection features. Various relxill_nk flavors are utilized to test the Kerr black hole hypothesis. The results obtained from our analysis provide stringent constraints on Johannsen deformation parameter α 13 with the highest precise to date, namely ${\alpha }_{13}={0.023}_{-0.038}^{+0.071}$ from relxillD_nk and ${\alpha }_{13}={0.006}_{-0.022}^{+0.045}$ from relxillion_nk, respectively, in 3σ credible lever, where the Johannsen metric reduces to the Kerr metric when α 13 vanishes. Furthermore, we investigate the best model fit results using Akaike information criterion and assess its systematic uncertainties.

Keywords: kerr metric; general relativity; astrophysical black holes; stellar mass black holes; x-ray astronomy
Transitions and Origin of the Type-B Quasi-periodic Oscillations in the Black Hole X-Ray Binary MAXI J1348-630

The fast transitions between different types of quasi-periodic oscillations (QPOs) are generally observed in black hole transient sources (BHTs). We present a detailed study of the timing and spectral properties of the transitions of type-B QPOs in MAXI J1348-630, observed by Insight-HXMT. The fractional rms variability-energy relationship and energy spectra reveal that type-B QPOs probably originate from jet precession. Compared to a weak power-law dominated power spectrum, when type-B QPOs are present, the corresponding energy spectrum shows an increase in the Comptonization component and the need for the xillverCp component, and a slight increase in the height of the corona when using the relxilllp model. Therefore, we suggest that a coupled inner disk-jet region is responsible for the observed type-B QPO transitions. The timescale for the appearance/disappearance of type-B QPOs is either long or short (seconds), which may indicate instability of the disk-jet structure. For these phenomena, we hypothesize that the Bardeen-Petterson effect causes the disk-jet structure to align with the BH spin axis or that the disappearance of small-scale jets bound by the magnetic flux tubes leads to the disappearance of type-B QPOs. We observed three events regarding the B/C transitions, one of which occurred over a short time period from ~9.2 Hz (C) to ~4.8 Hz (B). The energy spectral analysis for the other two transitions shows that when type-C QPO is present, the Comptonization flux is higher, the spectrum is harder, and the inner radius of the disk changes insignificantly. We suggest that type-C QPOs probably originate from relatively stronger jets or the corona.

Keywords: black hole physics; high energy astrophysics; x-ray binary stars; jets
GPS Measurements of Precipitable Water Vapor Can Improve Survey Calibration: A Demonstration from KPNO and the Mayall z-band Legacy Survey

Dual-band Global Positioning Satellite (GPS) measurements of precipitable water vapor (PWV) at the Kitt Peak National Observatory predict the overall per-image sensitivity of the Mayall z-band Legacy Survey (MzLS). The per-image variation in the brightness of individual stars is strongly correlated with the measured PWV and the color of the star. Synthetic stellar spectra through TAPAS transmission models successfully predict the observed PWV-induced photometric variation. We find that PWV absorption can be well approximated by a linear relationship with (airmass × PWV)0.6 and present an update on the traditional treatment in the literature. The MzLS zero-point sensitivity in electrons s-1 varies with a normalized-mean absolute deviation of 61 mmag. PWV variation accounts 23 mmag of this zero-point variation. The MzLS per-image absolute sensitivity decreases by 40 mmag per effective mm of PWV. The overall gray offset portion of this variation is corrected by the calibration to a reference catalog. But the relative calibration error between blue (r - z < 0.5 mag) versus red (1.2 mag < r - z) stars increases by 0.3-2 mmag per effective mm of PWV. We argue that GPS systems provide more precise PWV measurements than using differential measurements of stars of different colors and recommend that observatories install dual-band GPS as a low-maintenance, low-cost, auxiliary calibration system. We extend our results of the need for well-calibrated PWV measurements by presenting the calculations of the PWV photometric impact on three science cases of interest: stellar photometry, supernova cosmology, and quasar identification and variability.

Keywords: earth atmosphere; flux calibration; water vapor; astronomical methods; sky surveys; exoplanet detection methods; type ia supernovae; observational cosmology; quasars
The Large Magellanic Cloud Supernova Remnant MCSNR J0550-6823

We describe radio, optical, and X-ray observations of this rather faint, old Large Magellanic Cloud (LMC) supernova remnant. The [O III] emission forms a distinct shell, the remnant of the outer shock, which encloses the radio and X-ray emission and gives an estimate of age and explosion energy. Because of a collision with an LMC Hα filament, radio and X-ray emission are concentrated in the northern half of the remnant. The X-ray spectrum is well fit assuming the plasma is isothermal and in collisional equilibrium. The best-fit temperature is such that almost all energy is in lines from O, Ne, Mg, and Fe. The known distance, low extinction, and low interstellarmedium metallicity allow derivation of masses of several elements produced by the star and in the explosion. The masses of O, Ne, and Fe point to a Type II supernova from the explosion of a 20-25 M ⊙ star. The mass of Mg, however, is higher than that of almost all predictions, but some of this apparent excess might be due to a higher-temperature region in the X-ray-emitting material. Point-like background sources are examined to search for a neutron star, and one possible candidate is found just inside the shell of the remnant.

Keywords: x-ray astronomy; large magellanic cloud; type ii supernovae; supernova remnants
One-dimensional Microphysics Model of Venusian Clouds from 40 to 100 km: Impact of the Middle-atmosphere Eddy Transport and SOIR Temperature Profile on the Cloud Structure

We conducted a simulation of H2SO4 vapor, H2O vapor, and H2SO4–H2O liquid aerosols from 40 to 100 km, using a 1D Venus cloud microphysics model based on the one detailed in Imamura & Hashimoto. The cloud distribution obtained is in good agreement with in situ observations by Pioneer Venus and remote-sensing observations from Venus Express (VEx). Case studies were conducted to investigate sensitivities to atmospheric parameters, including eddy diffusion and temperature profiles. We find that efficient eddy transport is important for determining upper haze population and its microphysical properties. Using the recently updated eddy diffusion coefficient profile by Mahieux et al., our model replicates the observed upper haze distribution. The H2O vapor distribution is highly sensitive to the eddy diffusion coefficient in the 60–70 km region. This indicates that updating the eddy diffusion coefficient is crucial for understanding the H2O vapor transport through the cloud layer. The H2SO4 vapor abundance varies by several orders of magnitude above 85 km, depending on the temperature profile. However, its maximum value aligns well with observational upper limits found by Sandor et al., pointing to potential sources other than H2SO4 aerosols in the upper haze layer that contribute to the SO2 inversion layer. The best-fit eddy diffusion profile is determined to be ∼2 m2 s‑1 between 60 and 70 km and ∼360 m2 s‑1 above 85 km. Furthermore, the observed increase of H2O vapor concentration above 85 km is reproduced by using the temperature profile from the VEx/SOIR instrument.

Keywords: venus; atmospheric clouds; atmospheric composition; planetary atmospheres; atmospheric evolution
The Z Camelopardalis-type Star AY Piscium: Stellar and Accretion Disk Parameters

We present a new study of the Z Cam-type eclipsing cataclysmic variable AY Piscium with the aim of determining the fundamental parameters of the system and the structure of the accretion flow therein. We use time-resolved photometric observations supplemented by spectroscopy in the standstill, to which we applied our light-curve modeling techniques and the Doppler tomography method, to update system parameters. We found that the system has a massive white dwarf M WD = 0.90(4) M ☉, a mass ratio q = 0.50(3), and the effective temperature of a secondary T 2 = 4100(50) K. The system inclination is i = 74.°8(7). The orbital period of the system P orb = 0.217320523(8) day is continuously increasing at a rate of ${\dot{P}}_{\mathrm{orb}}=+7.6(5)\times {10}^{-9}$ day yr-1. The mass-transfer rate varies between 2.4 × 10-10 M ⊙ yr-1 in quiescence up to 1.36 × 10-8 M ⊙ yr-1 in outburst. The accretion disk transitions from the cooler, flared, steady-state disk to a warmer state with a practically constant and relatively high disk height. The mass-transfer rate is about 1.6 × 10-9 M ⊙ yr-1 in the standstill. The Balmer emission lines show a multicomponent structure similar to that observed in long-orbital-period nova-like systems. Out of standstill, the system exhibits outburst bimodality, with long outbursts being more prominent. We conclude that the Balmer emission lines in AY Psc are formed by the combination of radiation from the irradiated surface of the secondary, from the outflow zone, and from winds originating in the bright spot and the disk's inner part.

Keywords: close binary stars; cataclysmic variable stars; dwarf novae; z camelopardalis stars; fundamental parameters of stars; novae
New Limits on the Lorentz/CPT Symmetry Through 50 Gravitational-wave Events

Lorentz invariance plays a fundamental role in modern physics. However, tiny violations of the Lorentz invariance may arise in some candidate quantum gravity theories. Prominent signatures of the gravitational Lorentz invariance violation (gLIV) include anisotropy, dispersion, and birefringence in the dispersion relation of gravitational waves (GWs). Using a total of 50 GW events in the GW transient catalogs GWTC-1 and GWTC-2, we perform an analysis on the anisotropic birefringence phenomenon. The use of multiple events allows us to completely break the degeneracy among gLIV coefficients and globally constrain the coefficient space. Compared to previous results at mass dimensions 5 and 6 for the Lorentz-violating operators, we tighten the global limits of 34 coefficients by factors ranging from 2 to 7.

Keywords: gravitational waves; general relativity; compact binary stars
Multiwavelength Selected Compton-thick AGNs in Chandra Deep Field-South Survey

Even in deep X-ray surveys, Compton-thick active galactic nuclei (CT AGNs, NH ≥ 1.5 × 1024 cm-2) are difficult to identify due to X-ray flux suppression and their complex spectral shapes. However, the study of CT AGNs is vital for understanding the rapid growth of black holes and the origin of the cosmic X-ray background. In the local universe, the fraction of CT AGNs accounts for 30% of the whole AGN population. We expect a higher fraction of CT AGNs in deep X-ray surveys; however, only 10% of AGNs have been identified as CT AGNs in the 7 Ms Chandra Deep Field-South survey. In this work, we select 51 AGNs with abundant multiwavelength data. Using the method of the mid-infrared (mid-IR) excess, we select hitherto unknown eight CT AGN candidates in our sample. Seven of these candidates can be confirmed as CT AGNs based on the multiwavelength identification approach, and a new CT AGN (XID 133) is identified through the mid-IR diagnostics. We also discuss the X-ray origin of these eight CT AGNs and the reason why their column densities were underestimated in previous studies. We find that the multiwavelength approaches of selecting CT AGNs are highly efficient, provided the high quality of observational data. We also find that CT AGNs have a higher Eddington ratio than non-CT AGNs, and that both CT AGNs and non-CT AGNs show similar properties of host galaxies.

Keywords: active galactic nuclei; active galaxies; x-ray active galactic nuclei
A Spatially Resolved Analysis of Star Formation Burstiness by Comparing UV and Hα in Galaxies at z ∼ 1 with UVCANDELS

The UltraViolet imaging of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey Fields (UVCANDELS) program provides Hubble Space Telescope (HST)/UVIS F275W imaging for four CANDELS fields. We combine this UV imaging with existing HST/near-IR grism spectroscopy from 3D-HST+AGHAST to directly compare the resolved rest-frame UV and Hα emission for a sample of 979 galaxies at 0.7 < z < 1.5, spanning a range in stellar mass of 108-11.5 M ⊙. Using a stacking analysis, we perform a resolved comparison between homogenized maps of rest-UV and Hα to compute the average UV-to-Hα luminosity ratio (an indicator of burstiness in star formation) as a function of galactocentric radius. We find that galaxies below stellar mass of ~109.5 M ⊙, at all radii, have a UV-to-Hα ratio higher than the equilibrium value expected from constant star formation, indicating a significant contribution from bursty star formation. Even for galaxies with stellar mass ≳109.5 M ⊙, the UV-to-Hα ratio is elevated toward their outskirts (R/R eff > 1.5), suggesting that bursty star formation is likely prevalent in the outskirts of even the most massive galaxies, but is likely overshadowed by their brighter cores. Furthermore, we present the UV-to-Hα ratio as a function of galaxy surface brightness, a proxy for stellar mass surface density, and find that regions below ~107.5 M ⊙ kpc-2 are consistent with bursty star formation, regardless of their galaxy stellar mass, potentially suggesting that local star formation is independent of global galaxy properties at the smallest scales. Last, we find galaxies at z > 1.1 to have bursty star formation, regardless of radius or surface brightness.

Keywords: galaxy evolution; star formation
Mining the GALAH Data. I. Study of Five Super Lithium-rich Metal-poor Giants

The presence of a large amount of Li in giants is still a mystery. Most of the super Li-rich (SLR) giants reported in recent studies are in the solar metallicity regime. Here, we study the five metal-poor SLRs from the Galactic Archeology with HERMES Data Release 3, with their [Fe/H] ranging from ‑1.35 to ‑2.38 with lithium abundance of A(Li) ≥ 3.4 dex. The asteroseismic analysis reveals that none are on the red giant branch. The average period spacing (ΔP ) values indicate giants are in the core He-burning phase. All of them are low-mass giants (M < 1.5 M ⊙). Their location in the Hertzsprung–Russell diagram suggests one of them is in the red clump (RC) phase, and interestingly, the other four are much brighter and coincide with the early asymptotic giant branch phase. The analysis of the abundance reveals that C, O, Na, Ba, and Eu are normal in giants of respective metallicities and evolutionary phases. Further, we did not find any strong evidence of the presence of dust in the form of infrared excess or binarity from the available radial velocity data. We discuss a few scenarios for the existence of SLRs at higher luminosity, including past merger events. Our findings will help in understanding the production and evolution of Li among giants, in particular, during the RC phase and the post-RC phase.

Keywords: chemically peculiar stars; giant stars; lithium stars
A Quantum-mechanical Treatment of Electron Broadening in Strong Magnetic Fields

Spectral line-shape fitting is an extremely useful tool in determining the gravity of white dwarf stars. This method is so far limited to nonmagnetic white dwarfs largely because the theory of line broadening in high magnetic fields is not as complete as in the nonmagnetic case. Current Stark+Zeeman models treat plasma particles classically and ignore the motion of the nucleus. We develop the formalism for a quantum-mechanical treatment of the perturbing electrons and include the nuclear motion as part of the broadening and explore their relative importance. The conditions we explore are those found in white dwarf and neutron star atmospheres. We find that, contrary to previous studies, the quantized perturbing electrons create more broadening than perturbers on a straight-path trajectory. Additionally, the quantization of the plasma electrons gives rise to resonances away from the line center. The nuclear motion creates an additional electric field, which also leads to an increase in line broadening; however, this effect in neutron star atmospheres is not as large as previously estimated. This suggests that neutron star spectral lines are sensitive to density and that their mass and radius can be obtained from spectral line fitting, which would help constrain the neutron star equation of state.

Keywords: white dwarf stars; neutron stars; atomic spectroscopy; plasma physics; stellar atmospheres; fundamental parameters of stars
Porosity-filling Metamorphic Brines Explain Ceres's Low Mantle Density

Recent work has sought to constrain the composition and makeup of the dwarf planet Ceres's mantle, which has a relatively low density, between 2400 and 2800 kg m-3, as inferred by observations by the Dawn mission. Explanations for this low density have ranged from a high fraction of porosity-filled brines to a high fraction of organic matter. We present a series of numerical thermodynamic models that yield the mineralogy and fluid composition in the mantle as a function of Ceres's thermal evolution. We find that the resulting phase assemblage could have changed drastically since the formation of Ceres, as volatile-bearing minerals such as serpentine and carbonates would partially destabilize and release their volatiles as temperatures in the mantle reach their maximum about 3 Gyr after Ceres's formation. These volatiles consist mainly of aqueous fluids containing Na+ and HS- throughout the metamorphic evolution of Ceres and, in addition, high concentrations of CO2 at high temperatures relatively recently. The predicted present-day phase assemblage in the mantle, consisting of partially devolatilized minerals and 13-30 vol% fluid-filled porosity, is consistent with the mantle densities inferred from Dawn. The metamorphic fluids generated in Ceres's mantle may have replenished an ocean at the base of the crust and may even be the source of the Na2CO3 and NaHCO3 mineral deposits observed at Ceres's surface.

Keywords: ceres; mantle; planetary interior