adsabs/SciX_UAT_keywords huggingface dataset:
The Influence of Asymmetrical Distribution of Hemispheric Sunspot Areas on Some Solar Parameters' Periodicities during the Period 1945-2017: Wavelet Analysis

Monthly data of some solar parameters (the solar radio flux F10.7, the plage area PA, the coronal index CI, the solar mean magnetic field B, and the solar flare index SFI) during the period 1945-2017 have been classified into two groups (northern and southern) based on the distribution of the monthly averages of the hemispheric sunspot areas (SSAs). This has been done to investigate the symmetry and/or asymmetry in periodicities between the hemispheric groups for these parameters by utilizing the Morlet wavelet technique. For each of the considered parameters except B, it is observed that the most dominant and significant period (above the 95% confidence level) in both the wavelet spectra (WPS and GWS) for both hemispheric groups is the solar activity cycle at 10.7 yr during the entire time interval. The power values for other periods appeared to be quite small relative to that of the 10.7 yr period, and of less significance (below the 95% confidence level). For B, the most remarkable sign is the disappearance of the prominent peak of the solar activity cycle. The Hale cycle is clearly seen in both hemispheric groups of B, with a slight shift in time between the two hemispheric groups, and it increased through the entire considered duration. Periodicities of 10.7, 3.5, 1.5, and 0.8 yr have been observed in the northern hemispheric group of the parameters SSAs, F10.7, PA, CI, and SFI, indicating a possible correlation between them. For the southern hemispheric group, however, periodicities of 10.7, 5.4, and 0.8 yr have been revealed for the parameters F10.7, PA, and CI.

Keywords: solar activity; plages; active sun; sunspot cycle; sunspot number; sunspot groups; solar magnetic fields; solar corona; solar flares; solar physics
Chemical Tagging N-rich Field Stars with High-resolution Spectroscopy

We measure chemical abundances for over 20 elements of 15 N-rich field stars with high-resolution (R ∼ 30,000) optical spectra. We find that Na, Mg, Al, Si, and Ca abundances of our N-rich field stars are mostly consistent with those of stars from globular clusters (GCs). Seven stars are estimated to have [Al/Fe ] > 0.5, which is not found in most GC "first generation" stars. On the other hand, α element abundances (especially Ti) could show distinguishable differences between in situ stars and accreted stars. We discover that one interesting star, with consistently low [Mg/Fe], [Si/Fe], [Ca/Fe], [Ti/Fe], [Sc/Fe], [V/Fe], and [Co/Fe], show similar kinematics and [Ba/Eu] as other stars from the dissolved dwarf galaxy "Gaia-Sausage-Enceladus." The α-element abundances and the iron-peak element abundances of the N-rich field stars with metallicities - 1.25 ≤ [Fe/H] ≤ - 0.95 show consistent values with Milky Way field stars (we refer to Milky Way field stars as Milky Way halo field stars unless otherwise specified in this paper) rather than stars from dwarf galaxies, indicating that they were formed in situ. In addition, the neutron-capture elements of N-rich field stars show that most of them could be enriched by asymptotic giant branch stars with masses around 3-5 M⊙.

Keywords: stellar evolution; stellar abundances; chemically peculiar stars
Unraveling the Geologic History of Miranda's Inverness Corona

Miranda is the only icy body whose surface is known to contain the enigmatic features called corona-ovoid to trapezoidal areas of deformation. In this work, we seek to constrain potential formation mechanisms for Inverness Corona, the youngest known region on Miranda. To do this, we created the first detailed geologic map of Inverness, enabling the creation of a stratigraphic column of the order of events that formed this region. We employed a previously published Digital Elevation Model of the northern region of Inverness Corona to analyze the spacing of features in the region, which we propose to be extensional in origin. From this, we estimate an approximate brittle ice shell thickness of 2.5-3.8 km at the time of the region's formation, indicating that Miranda's brittle ice shell may have been relatively thin in the geologically recent past. We propose that Inverness formed from extension driven by a rising diapir or ice-shell thickening from a recent orbital resonance with Umbriel. The Uranus Orbiter and Probe mission is the highest priority flagship mission recommendation of the 2023-2032 Planetary Science and Astrobiology Decadal Survey. As such, we suggest measurements related to imaging, composition, gravity, and ice-shell thickness to gain an understanding of the geologic and orbital histories of the Uranian satellites, which would have implications for the evolution of the system as a whole.

Keywords: uranian satellites; planetary geology
X-Ray Energy Deposition Model for Simulating Asteroid Response to a Nuclear Planetary Defense Mitigation Mission

In the event of a potentially catastrophic asteroid impact, with sufficient warning time, deploying a nuclear device remains a powerful option for planetary defense if a kinetic impactor or other means of deflection proves insufficient. Predicting the effectiveness of a potential nuclear deflection or disruption mission depends on accurate multiphysics simulations of the device's X-ray energy deposition into the asteroid and the resulting material ablation. The relevant physics in these simulations span many orders of magnitude, require a variety of different complex physics packages, and are computationally expensive. Having an efficient and accurate way of modeling this system is necessary for exploring a mission's sensitivity to the asteroid's range of physical properties. To expedite future simulations, we present a completed X-ray energy deposition model developed using the radiation-hydrodynamics code Kull that can be used to initiate a nuclear mitigation mission calculation. The model spans a wide variety of possible mission initial conditions: four different asteroid-like materials at a range of porosities, two different source spectra, and a broad range of radiation fluences, source durations, and angles of incidence. Using blowoff momentum as the primary metric, the model-initiated simulation results match the full radiation-hydrodynamics results to within 10%.

Keywords: near-earth objects; asteroids; comets; radiative transfer simulations; hydrodynamical simulations
Polluting the Pair-instability Mass Gap for Binary Black Holes through Super-Eddington Accretion in Isolated Binaries

The theory for single stellar evolution predicts a gap in the mass distribution of black holes (BHs) between approximately 45 and 130 $\,{M}_{\odot }$ , the so-called "pair-instability mass gap." We examine whether BHs can pollute the gap after accreting from a stellar companion. To this end, we simulate the evolution of isolated binaries using a population synthesis code, where we allow for super-Eddington accretion. Under our most extreme assumptions, we find that at most about 2% of all merging binary BH systems contains a BH with a mass in the pair-instability mass gap, and we find that less than 0.5% of the merging systems has a total mass larger than 90 $\,{M}_{\odot }$ . We find no merging binary BH systems with a total mass exceeding 100 $\,{M}_{\odot }$ . We compare our results to predictions from several dynamical pathways to pair-instability mass gap events and discuss the distinguishable features. We conclude that the classical isolated binary formation scenario will not significantly contribute to the pollution of the pair-instability mass gap. The robustness of the predicted mass gap for the isolated binary channel is promising for the prospective of placing constraints on (I) the relative contribution of different formation channels, (II) the physics of the progenitors including nuclear reaction rates, and, tentatively, (III) the Hubble parameter.

Keywords: high energy astrophysics; compact binary stars; accretion; gravitational wave sources; binary stars; black holes
A Catalog of Emission-line Galaxies from the Faint Infrared Grism Survey: Studying Environmental Influence on Star Formation

We present a catalog of 208 0.3 < z < 2.1 emission-line galaxies (ELGs) selected from 1D slitless spectroscopy obtained using Hubble’s WFC3 G102 grism, as part of the Faint Infrared Grism Survey. We identify ELG candidates by searching for significant peaks in all continuum-subtracted G102 spectra and, where possible, confirm candidates by identifying consistent emission lines in other available spectra or with published spectroscopic redshifts. We provide derived emission-line fluxes and errors, redshifts, and equivalent widths for Hα λ6563, [O III] λλ4959, 5007, and [O II] λ3727 emission lines, for ELGs down to AB(F105W) >28 and >10-17 erg cm-2 s-1 line flux. We use the resulting line catalog to investigate a possible relationship between line emission and a galaxy’s environment. We use seventh-nearest-neighbor distances to investigate the typical surroundings of ELGs compared to non-ELGs, and we find that [O III] emitters are preferentially found at intermediate galaxy densities near galaxy groups. We characterize these ELGs in terms of the galaxy specific star formation rate (SFR) versus stellar mass and find no significant influence of environment on that relation. We calculate SFRs and find no dependence of SFR on local galaxy surface density for 0.3 < z < 0.8 Hα emitters and for 0.8 < z < 1.3 [O III] emitters. We find similar rates of close-pair interaction between ELGs and non-ELGs. For galaxy surface densities Σ ≤ 30 Mpc-2, we find no consistent effect of environment on star formation.

Keywords: galaxy environments; galaxy evolution; emission line galaxies
On the General Mechanism for the Gas-phase Reaction of Methanimine with a Radical Species in the Interstellar Medium: Some Failures and an Important Success

The gas-phase reactions of methanimine (CH2NH) with small radicals, such as CN, CP, CCH, and OH, have been extensively studied theoretically in the literature, and the presence of a common, general reaction mechanism has been postulated. Since methanimine is considered the main precursor of complex imines in the interstellar medium (ISM), the present study extends the investigation of its reaction with other small radicals that have already been detected in the ISM. These are SiN, SH, NO, NS, HCO, HCS, and C3N. The corresponding products are easily formulated on the basis of the aforementioned general mechanism, and to understand whether they can be formed in the ISM, a preliminary thermochemical study has been carried out. The only exothermic addition reaction is that occurring between CH2NH and the C3N radical. This reaction has been further investigated in order to accurately characterize its reactive potential energy surface, which has then been employed in ab initio transition state theory calculations to derive global rate coefficients. The products of the CH2NH + C3N reaction are new potential interstellar species, namely, the Z and E isomers of HNCHCCCN and CH2NCCCN. For the first time, their structural characterization has been reported. In addition, this work investigates the possibility of H-abstraction processes for each radical species considered, and re-examines the CH2NH + CP reaction to derive the corresponding rate constants, that were still missing in the literature.

Keywords: astrochemistry; reaction rates; molecular reactions; neutral-neutral reactions
Which Component of Solar Magnetic Field Drives the Evolution of Interplanetary Magnetic Field over the Solar Cycle?

The solar magnetic structure changes over the solar cycle. It has a dipole structure during solar minimum, where the open flux extends mainly from the polar regions into the interplanetary space. During maximum, a complex structure is formed with low-latitude active regions and weakened polar fields, resulting in spread open field regions. However, the components of the solar magnetic field that are responsible for long-term variations in the interplanetary magnetic field (IMF) are not clear, and the IMF strength estimated based on the solar magnetic field is known to be underestimated by a factor of 3-4 against the actual in situ observations (the open flux problem). To this end, we decomposed the coronal magnetic field into the components of the spherical harmonic function of degree and order (ℓ, m) using the potential field source surface model with synoptic maps from SDO/HMI for 2010-2021. As a result, we found that the IMF rapidly increased in 2014 December (7 months after the solar maximum), which coincided with the increase in the equatorial dipole, (ℓ, m) = (1, ±1), corresponding to the diffusion of active regions toward the poles and in the longitudinal direction. The IMF gradually decreased until 2019 December (solar minimum) and its variation corresponded to that of the nondipole component ℓ ≥ 2. Our results suggest that the understanding of the open flux problem may be improved by focusing on the equatorial dipole and the nondipole component and that the influence of the polar magnetic field is less significant.

Keywords: solar magnetic fields; solar coronal holes; interplanetary magnetic fields; solar corona; heliosphere; solar photosphere
Variations in Finite-difference Potential Fields

The potential field (PF) solution of the solar corona is a vital modeling tool for a wide range of applications, including minimum energy estimates, coronal magnetic field modeling, and empirical solar wind solutions. Given its popularity, it is important to understand how choices made in computing a PF may influence key properties of the solution. Here we study PF solutions for the global coronal magnetic field on 2012 June 13, computed with our high-performance finite-difference code POT3D. Solutions are analyzed for their global properties and locally around NOAA AR 11504, using the net open flux, open-field boundaries, total magnetic energy, and magnetic structure as metrics. We explore how PF solutions depend on (1) the data source, type, and processing of the inner boundary conditions; (2) the choice of the outer boundary condition height and type; and (3) the numerical resolution and spatial scale of information at the lower boundary. We discuss the various qualitative and quantitative differences that naturally arise by using different maps as input, and we illustrate how coronal morphology and open flux depend most strongly on the outer boundary condition. We also show how large-scale morphologies and the open magnetic flux are remarkably insensitive to model resolution, while the surface mapping and embedded magnetic complexity vary considerably. This establishes important context for past, current, and future applications of the PF for coronal and solar wind modeling.

Keywords: solar corona; solar coronal holes; solar surface; astronomy software; astronomy data analysis
Original Research by Young Twinkle Students (Orbyts): Ephemeris Refinement of Transiting Exoplanets II

We report follow-up observations of four transiting exoplanets, TRES-2 b, HAT-P-22 b, HAT-P-36 b and XO-2 b, as part of the Original Research By Young Twinkle Students (ORBYTS) program. These observations were taken using the Las Cumbres Observatory Global Telescope Network's (LCOGT) robotic 0.4 m telescopes and were analyzed using the HOlomon Photometric Software (HOPS). Such observations are key for ensuring accurate transit times for upcoming telescopes, such as the James Webb Space Telescope, Twinkle (Edwards et al. 2019b) and Ariel (Tinetti et al. 2018), which may seek to characterize the atmospheres of these planets. The data have been uploaded to ExoClock and a significant portion of this work has been completed by secondary school students in London.

Keywords: exoplanets; transit photometry; amateur astronomers
Charging and Electromagnetic Radiation during the Inspiral of a Black Hole-Neutron Star Binary

Because mergers of black hole-neutron star (BH-NS) binaries are widely argued to produce both gravitational and electromagnetic waves, these binaries are among the most attractive systems in the era of multi-messenger astronomy. In this paper we explore the charging processes of a moving BH in two types of charged surroundings and propose a new charging scenario differing from the elegant mechanism of Wald. During the inspiral of such a binary, the NS is strongly magnetized and the BH is moving inward. By considering this moving BH charging scenario, we find that the BH will increasingly accumulate enough net charge to light up the binary system at the inspiral stage. This charging process is universal no matter whether the BH spins or not. We show that our BH charging scenario can physically explain the BH's unipolar inductor mechanism in a BH-NS binary system. We calculate electromagnetic emission luminosities due to various energy dissipation mechanisms and find that the electric dipole radiation of the BH makes a dominant contribution to electromagnetic emission at the final stage of inspiral if the BH spins slowly.

Keywords: compact objects; black holes; neutron stars; general relativity; non-thermal radiation sources
A Large and Variable Leading Tail of Helium in a Hot Saturn Undergoing Runaway Inflation

Atmospheric escape shapes the fate of exoplanets, with statistical evidence for transformative mass loss imprinted across the mass–radius–insolation distribution. Here, we present transit spectroscopy of the highly irradiated, low-gravity, inflated hot Saturn HAT-P-67 b. The Habitable Zone Planet Finder spectra show a detection of up to 10% absorption depth of the 10833 Å helium triplet. The 13.8 hr of on-sky integration time over 39 nights sample the entire planet orbit, uncovering excess helium absorption preceding the transit by up to 130 planetary radii in a large leading tail. This configuration can be understood as the escaping material overflowing its small Roche lobe and advecting most of the gas into the stellar—and not planetary—rest frame, consistent with the Doppler velocity structure seen in the helium line profiles. The prominent leading tail serves as direct evidence for dayside mass loss with a strong day-/nightside asymmetry. We see some transit-to-transit variability in the line profile, consistent with the interplay of stellar and planetary winds. We employ one-dimensional Parker wind models to estimate the mass-loss rate, finding values on the order of 2 × 1013 g s‑1, with large uncertainties owing to the unknown X-ray and ultraviolet (XUV) flux of the F host star. The large mass loss in HAT-P-67 b represents a valuable example of an inflated hot Saturn, a class of planets recently identified to be rare, as their atmospheres are predicted to evaporate quickly. We contrast two physical mechanisms for runaway evaporation: ohmic dissipation and XUV irradiation, slightly favoring the latter.

Keywords: exoplanet atmospheres; exoplanet evolution; exoplanet atmospheric dynamics; exoplanet atmospheric variability; stellar winds; high resolution spectroscopy
Evaluating Non-LTE Spectral Inversions with ALMA and IBIS

We present observations of a solar magnetic network region in the millimeter continuum with the Atacama Large Millimeter/submillimeter Array (ALMA) and in the Ca 8542 and Na 5896 Å spectral lines with the Interferometric Bidimensional Spectrometer (IBIS). Our goal is to compare the measurement of local gas temperatures provided by ALMA with the temperature diagnostics provided by non-LTE inversions using the STockholm inversion Code (STiC). In performing these inversions, we find that using column mass as the reference height scale, rather than optical depth, provides more reliable atmospheric profiles above the temperature minimum and that the treatment of non-LTE hydrogen ionization brings the inferred chromospheric temperatures into better agreement with the ALMA measurements. The Band 3 brightness temperatures are higher but well correlated spatially with the inversion-derived temperatures at the height of formation of the Ca 8542 line core. The Band 6 temperatures instead do not show good correlations with the temperatures at any specific layer in the inverted atmospheres. We then performed inversions that included the millimeter-continuum intensities as an additional constraint. Incorporating Band 3 generally resulted in atmospheres showing a strong temperature rise in the upper atmosphere, while including Band 6 led to significant regions of anomalously low temperatures at chromospheric heights. This is consistent with the idea that the Band 6 emission can come from a combination of heights ranging from the temperature minimum to upper chromosphere. The poor constraints on the chromospheric electron density with existing inversion codes introduces difficulties in determining the height(s) of formation of the millimeter continuum as well as uncertainties in the temperatures derived from the spectral lines.

Keywords: solar chromosphere; millimeter astronomy; solar atmosphere; radiative transfer
Nuclear Physics with Gravitational Waves from Neutron Stars Disrupted by Black Holes

Gravitational waves from neutron star-black hole (NSBH) mergers that undergo tidal disruption provide a potential avenue to study the equation of state of neutron stars and hence the behavior of matter at its most extreme densities. We present a phenomenological model for the gravitational-wave signature of tidal disruption, which allows us to measure the disruption time. We carry out a study with mock data, assuming an optimistically nearby NSBH event with parameters tuned for measuring the tidal disruption. We show that a two-detector network of 40 km Cosmic Explorer instruments can measure the time of disruption with a precision of ≈0.5 ms, which corresponds to a constraint on the neutron star radius of ≈0.7 km (90% credibility). This radius constraint is wider than the constraint obtained by measuring the tidal deformability of the neutron star of the same system during the inspiral. Moreover, the neutron star radius is likely to be more tightly constrained using binary neutron star mergers. While NSBH mergers are important for the information they provide about stellar and binary astrophysics, they are unlikely to provide insights into nuclear physics beyond what we will already know from binary neutron star mergers.

Keywords: gravitational waves; nuclear astrophysics
On the Formation of SS433

SS433 is an extraordinary X-ray binary that is ejecting bipolar jets at 26% the speed of light. Associated with the supernova-like shell W50, SS433 is also probably one of the youngest X-ray binaries with an age of ≲105 yr. However, the masses of the two components in SS433 and even the nature of the compact object are still under debate. In this work, assuming that the compact object is a black hole, we employ a binary population synthesis method to study the formation of SS433. We use previous estimates of the age of W50 and the duration of the jet activity to constrain the evolutionary history. Our calculations suggest that SS433 likely harbored a Hertzsprung gap star at the beginning of the current Roche-lobe overflow phase. The masses of the black hole and the optical/donor star in SS433 suggested by the simulations are around 8 M⊙ and 24 M⊙, respectively. Future measurement of the donor mass and radius can help infer not only the origin of the binary but also the nature of the nebula W50.

Keywords: stellar evolution; black holes; x-ray binary stars