Sazuna/UAT_keywords huggingface dataset:
Spectroscopy of Supernova Remnants and Candidates in M31. With a star formation rate of order 0.4 M⊙ yr‑1, M31 should have a significant population of supernova remnants (SNRs) and, in fact, 156 SNRs and SNR candidates have been suggested by J. H. Lee &amp; M. G. Lee, by searching for nebulae with elevated [S II]/Hα ratios in narrowband images. Here, we use a combination of low- and high-resolution optical spectroscopy obtained with Hectospec on the MMT to characterize 152 of these nebulae. Of these candidates, we find 93 nebulae that have [S II]/Hα ratios that exceed 0.4, the traditional ratio used to separate SNRs from H II regions, strongly suggesting that at least these objects are SNRs. Our high-resolution spectroscopy reveals 108 nebulae that have velocity widths in Hα (full width at 20% peak flux) that exceed 50 km s‑1, significantly larger than found in H II regions. There are 72 objects that satisfy both tests. Here, we discuss the spectroscopic characteristics of all of the objects in our sample, and the likelihood that other objects in the sample of J. H. Lee &amp; M. G. Lee are also SNRs, and we briefly consider confirmation by X-ray, radio, and UV observations. We also discuss several new candidates that have been identified serendipitously in the course of examining a large amount of archival Hectospec data.

Keywords: Supernova remnants, Andromeda Galaxy, Planetary nebulae, H II regions
The All-sky Impact of the LMC on the Milky Way Circumgalactic Medium. The first infall of the LMC into the Milky Way (MW) represents a large and recent disruption to the MW circumgalactic medium (CGM). In this work, we use idealized, hydrodynamical simulations of an MW-like CGM embedded in a dark matter halo with an infalling LMC-like satellite initialized with its own CGM to understand how the encounter is shaping the global physical and kinematic properties of the MW CGM. First, we find that the LMC drives order-unity enhancements in MW CGM density, temperature, and pressure due to a   shock from the supersonic CGM─CGM collision. The resulting shock front extends from the LMC to beyond ∼R200,MW, amplifying column densities, X-ray brightness, thermal Sunyaev─Zeldovich distortion, and potentially synchrotron emission from cosmic rays over large angular scales across the southern hemisphere. Second, the MW's reflex motion relative to its outer halo induces a dipole in CGM radial velocities, with vR ± 30─50 km s−1 at R &gt; 50 kpc in the northern and southern hemispheres, respectively, consistent with measurements in the stellar halo. Finally, ram pressure strips most of the LMC's CGM, leaving ∼108−9M⊙ warm ionized gas along the past orbit of the LMC, moving at high radial and/or tangential velocities ∼50─100 kpc from the MW. Massive satellites like the LMC leave their mark on the CGM structure of their host galaxies, and signatures of such interactions may be observable in key all-sky tracers of the MW CGM and those of other massive galaxies.

Keywords: Hydrodynamical simulations, Galactic and extragalactic astronomy, Large Magellanic Cloud, Circumgalactic medium
BEACON: JWST NIRCam Pure-parallel Imaging Survey. I. Survey Design and Initial Results. We introduce the Bias-free Extragalactic Analysis for Cosmic Origins with NIRCam (BEACON) survey, a JWST Cycle 2 program allocated up to 600 pure-parallel hours of observations. BEACON explores high-latitude areas of the sky with JWST/NIRCam over ∼100 independent sight lines, totaling ∼0.3 deg2, reaching a median F444W depth of ≈28.2 AB mag (5σ). Based on existing JWST observations in legacy fields, we estimate that BEACON will photometrically identify 25–150 galaxies at z &gt; 10 and 500–1000 at z ∼ 7–10 uniquely enabled by an efficient multiple filter configuration spanning 0.9–5.0 μm. The expected sample size of z &gt; 10 galaxies will allow us to obtain robust number density estimates and to discriminate between different models of early star formation. In this paper, we present an overview of the survey design and initial results using the first 19 fields. We present 129 galaxy candidates at z ≳7 identified in those fields, including 11 galaxies at z ≳10 and several UV-luminous (MUV &lt; ‑21 mag) galaxies at z ∼ 8. The number densities of z &lt; 13 galaxies inferred from the initial fields are overall consistent with those in the literature. Despite reaching a considerably large volume (∼105 Mpc3), however, we find no galaxy candidates at z &gt; 13, providing us with a complimentary insight into early galaxy evolution with minimal cosmic variance. We publish imaging and catalog data products for these initial fields. Upon survey completion, all BEACON data will be coherently processed and distributed to the community along with catalogs for redshift and other physical quantities.

Keywords: Reionization, High-redshift galaxies, Galaxies
Secret of Longevity: Protoplanetary Disks as a Source of Gas in Debris Disks. While protoplanetary disks (PPDs) are generally thought to disperse within several million years, recent observations have revealed gas in their older counterparts, debris disks. The origin of this gas remains uncertain, with one possibility being the unexpectedly long survival of PPDs (the primordial-origin scenario). To explore the plausibility of this scenario, we conduct 1D disk evolution simulations, varying parameters like stellar mass, disk mass, turbulent stress, and the model of magnetohydrodynamic winds, while incorporating stellar evolution to account for time-varying photoevaporation rates. Our focus is on disks where small grains are depleted, as these are potentially long lived due to reduced far-ultraviolet photoevaporation. Our results show that gas in these disks can survive beyond 10 Myr regardless of the stellar mass, provided they are initially massive (Mdisk ≈ 0.1 M*) with relatively weak turbulent stress (α ≪ 10‑2). The longest lifetimes are consistently found for M* = 2 M⊙ across a wide parameter space, with gas typically persisting at ∼10–103 au. Roughly estimated CO masses for these disks fall within the observed range for the most massive gas-rich debris disks around early A stars. These alignments support the plausibility of the primordial-origin scenario. Additionally, our model predicts that accretion persists for as long as the disk survives, which could explain the accretion signatures detected in old disks hosted by low-mass stars, including Peter Pan disks. Our finding also suggests that ongoing accretion may exist in gas-rich debris disks. Thus, searching for accretion signatures could be a key to determining the origins of gas in debris disks.

Keywords: Debris disks, Protoplanetary disks, Circumstellar disks
JWST/MIRI Detection of [Ne v] and [Ne VI] in M83: Evidence for the Long Sought-after Active Galactic Nucleus?. We report the first detections of [Ne v] λ14.3 μm and [Ne VI] λ7.7 μm at high confidence (S/N ≥ 6) in the nuclear region of the nearby spiral galaxy M83. Emission-line maps of these high-ionization lines show several compact structures. Specifically, the [Ne VI] emission is located at 140 pc from the optical nucleus and appears as a point source of size ≲18 pc (FWHM ≲ 0 8). We investigate the possible source of this extreme emission through comparison with photoionization models and ancillary data. We find that photoionization models of fast radiative shocks are able to reproduce the observed high-excitation emission-line fluxes only for the lowest preshock density available in the library, n = 0.01 cm‑3. Additionally, tailored active galactic nucleus (AGN) photoionization models assuming a two-zone structure are compatible with the observed high-ionization fluxes. Our simple AGN model shows that the emission at the location of the [Ne VI] source can be the result of a cloud being ionized by the radiation cone of an AGN. We stress, however, that to definitively confirm an AGN as the main source of the observed emission, more complex modeling accounting for different geometries is required. Previously known as a purely starburst system, these new findings of the nuclear region of M83 will require a reassessment of its nature and of objects similar to it, particularly now that we have access to the unparalleled infrared sensitivity and spatial resolution of the James Webb Space Telescope.

Keywords: Starburst galaxies, Interstellar medium
Filamentary Electron-beam Heating in Solar Flares. Radiation-hydrodynamic simulations of the solar-flare chromospheric emission very often lead to an excess of the line intensities when compared to observations. Various studies suggest that the flare loops have a certain intrinsic, multithread internal structure, which is still not resolved by current telescopes. Taking this into account, we want to test and compare two different approaches for flare simulations. The first approach is the commonly used one, based on a continuous flux of nonthermal electrons heating the chromosphere for a rather long time. In the second approach, we consider the heating by short beam pulses consecutively within spatially unresolved filaments. Superposition of these short-duration pulses gives us the same electron-beam flux as in the first approach, but we are showing that the filamentary heating generates lower intensities in both the Hα and Mg II k lines, as expected.

Keywords: Radiative transfer simulations, Solar chromosphere, Solar flares, Hydrodynamical simulations
Probing Solar Modulation of AMS-02 Time-dependent D, <SUP>3</SUP>He, and <SUP>4</SUP>He Fluxes with Modified Force-field Approximation Models. The AMS-02 experiment recently published time-dependent fluxes of deuterons (D) from 2011 May to 2021 April, divided into 33 periods of four Bartels rotations each. These temporal structures are associated with solar modulation. In this study, three modified force-field approximations (FFAs) are employed to examine the long-term behavior of cosmic-ray isotopes such as D, 3He, and 4He, as well as the ratios D/3He and 3He/4He. The solar modulation potential is rigidity dependent for these modified FFA models. Due to the unknown local interstellar spectrum (LIS) for these isotopes, we utilize the non-LIS method for solar modulation. By fitting to the AMS-02 time-dependent fluxes, we derive the solar modulation parameters. Our findings prove the assumption in literature that all isotopes can be fitted using the same solar modulation parameters, and it is shown that the modified FFA models provide valid parameterization for solar modulation. Based on these, we forecast the daily fluxes of D, 3He, and 4He from 2011 to 2020.

Keywords: Galactic cosmic rays, Heliosphere
Spin and Obliquity Evolution of Hot Jupiter Hosts from Resonance Locks. When a hot Jupiter orbits a star whose effective temperature exceeds ∼6100 K, its orbit normal tends to be misaligned with the stellar spin axis. Cooler stars typically have smaller obliquities, which may have been damped by hot Jupiters in resonance lock with axisymmetric stellar gravity modes (azimuthal number m = 0). Here we allow for resonance locks with nonaxisymmetric modes, which affect both stellar obliquity and spin frequency. Obliquities damp for all modes (‑2 ≤ m ≤ 2). Stars spin-up for m &gt; 0, and spin-down for m &lt; 0. We carry out a population synthesis that assumes hot Jupiters form misaligned around both cool and hot stars, and subsequently lock onto modes whose m-values yield the highest mode energies for given starting obliquities. Core hydrogen burning enables hot Jupiters to torque low-mass stars, but not high-mass stars, into spin–orbit alignment. Resonance locking plus stellar spin-down from magnetic braking largely reproduces observed obliquities and stellar rotation rates and how they trend with stellar effective temperature and orbital separation. The possible suppression of resonance locking by nonlinear dissipation of gravity waves remains an outstanding issue.

Keywords: Hot Jupiters, Tidal interaction, Star-planet interactions, Exoplanet formation, Stellar evolution
Quantifying Systematic Uncertainties in White Dwarf Cooling Age Determinations. Cooling ages of white dwarfs are routinely determined by mapping effective temperatures and masses to ages using evolutionary models. Typically, the reported uncertainties on cooling ages only consider the error propagation of the uncertainties on the spectroscopically or photometrically determined Teff and mass. However, cooling models are themselves uncertain, given their dependence on many poorly constrained inputs. This paper estimates these systematic model uncertainties. We use MESA to generate cooling sequences of 0.5─1.0 M⊙ hydrogen-atmosphere white dwarfs with carbon─oxygen cores under different assumptions regarding the chemical stratification of their core, the thickness of their helium envelope, their hydrogen content, and the conductive opacities employed in the calculations. The parameter space explored is constrained by the range of values predicted by a variety of stellar evolution models and inferred from asteroseismological studies. For a 0.6 M⊙white dwarf, we find an uncertainty of 0.03 Gyr at 10,000 K (corresponding to a 5% relative uncertainty) and 0.8 Gyr at 4000 K (9%). This uncertainty is significant, as it is comparable to the age uncertainty obtained by propagating the measurement errors on Teff and mass for a typical white dwarf. We also separately consider the potential impact of 22Ne shell distillation, which plausibly leads to an additional uncertainty of ∼1 Gyr for crystallized white dwarfs. We provide a table of our simulation results that can be used to evaluate the systematic model uncertainty based on a white dwarf's Teff and mass. We encourage its use in all future studies where white dwarf cooling ages are measured.

Keywords: White dwarf stars, Uncertainty bounds, Stellar ages, Stellar evolution
VLASS Tidal Disruption Events with Optical Flares. II. Discovery of Two TDEs with Intermediate Width Balmer Emission Lines and Connections to the Ambiguous Extreme Coronal Line Emitters. The multiwavelength properties of radio-emitting tidal disruption events (TDEs) are poorly understood. In a previous paper, we presented the first sample of radio-selected, optically detected TDEs, which included two events (VT J1008 and VT J2012) associated with late-time (∼2 yr post-optical flare) intermediate width emission lines that are largely unprecedented from TDEs. In this paper, we investigate these two events in detail. The multiwavelength properties of these events are otherwise consistent with optically selected TDEs. They are hosted by green valley, E+A/Balmer dominated galaxies with low star formation rates and black holes masses MBH ≈ 105‑6 M⊙. The optical flare shapes are fully consistent with those of optically selected TDEs, although they are slightly faint and cool at peak. The radio emission from both events is consistent with wide-angle, nonrelativistic outflows with LR(GHz) ∼ 1038 erg s‑1. Balmer and helium emission lines are detected from both events with FWHM ∼700 km s‑1 and asymmetric line profiles. VT J1008 additionally shows coronal line emission with a similar width. The lines from VT J2012 are redshifted by ∼700 km s‑1 relative to the host galaxy. We show that these events share many characteristics in common with the ambiguous class of extreme coronal line emitters. We argue that the lines are likely associated with a radiative shock or dense, photoionized clumps of outflowing gas in the circumnuclear medium.

Keywords: Accretion, Supermassive black holes, Tidal disruption
Evidence for a Link between Turbulence and the Generation of Ion Cyclotron Waves via the Helicity Barrier Effect in the Solar Wind. The dissipation and heating of collisionless plasma in the inner heliosphere is a significant unresolved problem in space physics. The helicity barrier theory suggests a possible mechanism for these processes, but it requires validation through analysis of spacecraft data. We assess the validity of the parameter regime associated with the helicity barrier in the solar wind over a range of heliocentric distances using Parker Solar Probe and Solar Orbiter. We use the Politano–Pouquet law to estimate the energy and cross helicity cascade rates in the solar wind and compare the values to radial distance, the polarization, and prevalence of ion cyclotron waves. We find that the amplitude and prevalence of left-hand-polarized waves in the solar wind is directly correlated with the total energy and the cross-helicity cascade rate of the turbulence. Our measurements are consistent with the helicity barrier being active in all solar wind intervals that we study, and we demonstrate the uncertainty in calculating energy and the cross-helicity cascade rates in this study.

Keywords: Interplanetary turbulence, Magnetohydrodynamics, Solar wind
Chicago–Carnegie Hubble Program: A Multiwavelength Search for the Effects of Metallicity on the Cepheid Distance Scale. I. Empirical Evidence. Understanding the effects of metallicity on the multiwavelength properties of Cepheids is of continuing importance for their effective use as extragalactic distance indicators and an accurate measure of the Hubble constant, H0. Quantifying the magnitude, and even the sign, of a metallicity effect, at one or more wavelengths, has been and continues to be challenging, and has not yet converged. Here we present the results of a multipronged investigation looking for empirical evidence of correlations linking the metallicities of Cepheids to the zero-point of the their multiwavelength period–luminosity relations. The empirical evidence leads to a self-consistent conclusion based on six tests, across many galaxies and in up to nine different bandpasses, from the optical to the mid-infrared. The major result is that for classical Cepheids, in none of the cases examined is there a metallicity effect, of any statistical significance, detected at any of the wavelengths examined. However, theoretical models of stellar atmospheres clearly show that metallicity will impact each of the bandpasses differently: the level of this effect is largest in the ultraviolet (where line blanketing is most intense), reversing sign in the optical (due to flux redistribution from the UV), and then asymptotically falling back to zero from the red to the far infrared. Close examination of these models reveals infrared regions in Cepheid spectral energy distributions that allow for the simultaneous correction for extinction and metallicity differences by the judicious combination of infrared filters alone, one centered at 1.2 μm and the other at 3.6 μm. Both of these bands can be simultaneously observed in single exposures using the dual-channel imager NIRCam on JWST.

Keywords: Distance indicators, Cepheid variable stars, Cepheid distance, Open star clusters, Metallicity
From Young Massive Clusters to Old Globular Clusters: Density Profile Evolution and Intermediate-mass Black Hole Formation. The surface brightness profiles of globular clusters are conventionally described with the well-known King profile. However, observations of young massive clusters (YMCs) in the local Universe suggest that they are better fit by simple models with flat central cores and simple power-law densities in their outer regions (such as the Elson-Fall-Freeman, or EFF, profile). Depending on their initial central density, YMCs may also facilitate large numbers of stellar collisions, potentially creating very massive stars that will directly collapse into intermediate-mass black holes (IMBHs). Using Monte Carlo N-body models of YMCs, we show that EFF-profile clusters transform to Wilson or King profiles through natural dynamical evolution, but that their final W0 parameters do not strongly correlate to their initial concentrations. In the densest YMCs, runaway stellar mergers can produce stars that collapse into IMBHs, with their final masses depending on the treatment of the giant star envelopes during collisions. If a common-envelope prescription is assumed, where the envelope is partially or entirely lost, stars form with masses up to 824 M⊙, collapsing into IMBHs of 232 M⊙. Alternatively, if no mass loss is assumed, stars as massive as 4000 M⊙ can form, collapsing into IMBHs of ∼4000 M⊙. In doing so, these runaway collisions also deplete the clusters of their primordial massive stars, reducing the number of stellar-mass BHs by as much as ∼40%. This depletion will accelerate the core collapse, suggesting that the process of IMBH formation itself may produce the high densities observed in some core-collapsed clusters.

Keywords: Intermediate-mass black holes, Young star clusters
Accretion Bursts in Young Intermediate-mass Stars Make Planet Formation Challenging. We investigate the occurrence of accretion bursts, dust accumulation, and the prospects for planetesimal formation in a gravitationally unstable magnetized protoplanetary disk (PPD) with globally suppressed but episodically triggered magnetorotational instability (MRI), particularly in young intermediate-mass stars (YIMSs) but with a brief comparison to low-mass counterparts. We use numerical magnetohydrodynamics simulations in the thin-disk limit (the Formation and Evolution Of a Star And its circumstellar Disk, or FEOSAD, code) to model the formation and long-term evolution of a gravitationally unstable magnetized PPD, including dust dynamics and growth, since the collapse of a massive slowly rotating prestellar cloud core. Massive gas concentrations and dust rings form within the inner disk region owing to the radially varying efficiency of mass transport by gravitational instability (GI). These rings are initially susceptible to streaming instability (SI). However, gradual warming of the dust rings thanks to high opacity and GI-induced influx of matter increases the gas temperature above a threshold for the MRI to develop via thermal ionization of alkaline metals. The ensuing MRI bursts destroy the dust rings, making planetesimal formation via SI problematic. In the later evolution phase, when the burst activity starts to diminish, SI becomes inefficient because of growing dust drift velocity and a more extended inner dead zone, both acting to reduce the dust concentration below the threshold for the SI to develop. Low-mass objects appear to be less affected by these adverse effects. Our results suggest that disks around YIMSs may be challenging environments for planetesimal formation via SI. This may explain the dearth of planets around stars with M* &gt; 3.0 M⊙.

Keywords: Dust physics, Magnetohydrodynamics, Exoplanets, Intermediate-type stars, Pre-main sequence stars, Star formation, Protoplanetary disks, Protostars, Planet formation
New Tests on Lorentz Invariance Violation Using Energy-resolved Polarimetry of Gamma-Ray Bursts. One of the manifestations of Lorentz invariance violation (LIV) is vacuum birefringence, which leads to an energy-dependent rotation of the polarization plane of linearly polarized photons arising from an astrophysical source. Here we use the energy-resolved polarization measurements in the prompt gamma-ray emission of five bright gamma-ray bursts (GRBs) to constrain this vacuum birefringent effect. Our results show that at the 95% confidence level, the birefringent parameter η characterizing the broken degree of Lorentz invariance can be constrained to be  , which represents an improvement of at least 8 orders of magnitude over existing limits from multiband optical polarization observations. Moreover, our constraints are competitive with previous best bounds from the single gamma-ray polarimetry of other GRBs. We emphasize that, thanks to the adoption of the energy-resolved polarimetric data set, our results on η are statistically more robust. Future polarization measurements of GRBs at higher energies and larger distances would further improve LIV limits through the birefringent effect.

Keywords: Gravitation, Gamma-ray bursts, Particle astrophysics, Quantum gravity