Sazuna/UAT_keywords huggingface dataset:
Massive Protostellar Disks as a Hot Laboratory of Silicate Grain Evolution. Typical accretion disks around massive protostars are hot enough for water ice to sublimate. We here propose to utilize the massive protostellar disks for investigating the collisional evolution of silicate grains with no ice mantle, which is an essential process for the formation of rocky planetesimals in protoplanetary disks around lower-mass stars. We, for the first time, develop a model of massive protostellar disks that includes the coagulation, fragmentation, and radial drift of dust. We show that the maximum grain size in the disks is limited by collisional fragmentation rather than by radial drift. We derive analytic formulae that produce the radial distribution of the maximum grain size and dust surface density in the steady state. Applying the analytic formulae to the massive protostellar disk of GGD27-MM1, where the grain size is constrained from a millimeter polarimetric observation, we infer that the silicate grains in this disk fragment at collision velocities above ≈10 m s-1. The inferred fragmentation threshold velocity is lower than the maximum grain collision velocity in typical protoplanetary disks around low-mass stars, implying that coagulation alone may not lead to the formation of rocky planetesimals in those disks. With future measurements of grain sizes in massive protostellar disks, our model will provide more robust constraints on the sticking property of silicate grains.

Keywords: Massive stars, Astrophysical dust processes, Star formation, Protoplanetary disks, Planetesimals, Stellar accretion disks, Protostars, Astronomical location
Deviation from a Continuous and Universal Turbulence Cascade in NGC 6334 due to Massive Star Formation Activity. We use molecular line data from the Atacama Large Millimeter/submillimeter Array, Submillimeter Array, James Clerk Maxwell Telescope, and NANTEN2 to study the multiscale (~15-0.005 pc) velocity statistics in the massive star formation region NGC 6334. We find that the nonthermal motions revealed by the velocity dispersion function (VDF) stay supersonic over scales of several orders of magnitude. The multiscale nonthermal motions revealed by different instruments do not follow the same continuous power law, which is because the massive star formation activities near central young stellar objects have increased the nonthermal motions in small-scale and high-density regions. The magnitudes of VDFs vary in different gas materials at the same scale, where the infrared dark clump N6334S in an early evolutionary stage shows a lower level of nonthermal motions than other more evolved clumps due to its more quiescent star formation activity. We find possible signs of small-scale-driven (e.g., by gravitational accretion or outflows) supersonic turbulence in clump N6334IV with a three-point VDF analysis. Our results clearly show that the scaling relation of velocity fields in NGC 6334 deviates from a continuous and universal turbulence cascade due to massive star formation activities.

Keywords: Star formation, Molecular clouds, Interstellar medium
Very Metal-poor Stars in the Solar Vicinity: Kinematics and Abundance Analysis. Very metal-poor stars contain crucial information on the Milky Way's infancy. In our previous study we derived a mean age of ~13.7 Gyr for a sample of these stars in the Sun's vicinity. In this work, we investigate the chemical and kinematic properties of these stars with the goal of obtaining some insights into their origin and their parent population. We did not find any Al-Mg anticorrelation, which leads us to the conclusion that these stars did not form in globular clusters, while the detailed analysis of their orbital parameters reveals that these stars are most probably associated with the pristine bulge of the Milky Way. We then sketch a scenario for the formation of the Milky Way in which the first structure to form was the bulge through rapid collapse. The other components have grown later on, with a significant contribution of accreted structures.

Keywords: Field stars, Metallicity, Milky Way formation, Stellar kinematics
The Masses of Supernova Remnant Progenitors in M33. Using resolved optical stellar photometry from the Panchromatic Hubble Andromeda Treasury Triangulum Extended Region survey, we measured the star formation history near the position of 85 supernova remnants (SNRs) in M33. We constrained the progenitor masses for 60 of these SNRs, finding that the remaining 25 remnants had no local star formation in the last 56 Myr, consistent with core-collapse supernovae, making them potential Type Ia candidates. We then infer a progenitor mass distribution from the age distribution, assuming single star evolution. We find that the progenitor mass distribution is consistent with being drawn from a power law with an index of $-{2.9}_{-1.0}^{+1.2}$ . Additionally, we infer a minimum progenitor mass of ${7.1}_{-0.2}^{+0.1}$ M ⊙ from this sample, consistent with several previous studies, providing further evidence that stars with ages older than the lifetimes of single 8 M ⊙ stars are producing supernovae.

Keywords: Stellar populations, Massive stars, Supernovae, Stellar evolution
The Early Light Curve of the Type Ia Supernova 2021hpr in NGC 3147: Progenitor Constraints with the Companion Interaction Model. The progenitor system of Type Ia supernovae (SNe Ia) is expected to be a close binary system consisting of a carbon/oxygen white dwarf (WD) and a nondegenerate star or another WD. Here, we present results from high-cadence monitoring observations of SN 2021hpr in a spiral galaxy, NGC 3147, and constraints on the progenitor system based on its early multicolor light-curve data. First, we classify SN 2021hpr as a normal SN Ia from its long-term photometric and spectroscopic data. More interestingly, we found a significant "early excess" in the light curve over a simple power-law ~t 2 evolution. The early light curve evolves from blue to red to blue during the first week. To explain this, we fitted the early part of the BVRI-band light curves with a two-component model consisting of ejecta-companion interaction and a simple power-law model. The early excess and its color can be explained by shock-cooling emission due to a companion star having a radius of 8.84 ± 0.58 R ⊙. We also examined Hubble Space Telescope preexplosion images, finding no detection of a progenitor candidate, consistent with the above result. However, we could not detect signs of a significant amount of stripped mass from a nondegenerate companion star (≲0.003 M ⊙ for Hα emission). The early excess light in the multiband light curve supports a nondegenerate companion in the progenitor system of SN 2021hpr. At the same time, the nondetection of emission lines opens the door for other methods to explain this event.

Keywords: White dwarf stars, Transient sources, Type Ia supernovae, Time domain astronomy, Astrophysical explosive burning, Supernovae
Field-aligned and Magnetic Reconnection Flows in a Magnetohydrodynamic Simulation of Prominence-cavity System. Nested ring-shaped line-of-sight (LOS) oriented flows in coronal cavities have been observed in recent years but rarely explained. Using a magnetohydrodynamic simulation of a prominence-cavity system, we investigate the relationship between the simulated field-aligned flows, magnetic reconnection flows, and the LOS-oriented flows observed by the Coronal Multi-Channel Polarimeter. The field-aligned flows are along magnetic field lines toward the dips and driven by the hydrodynamic forces exerted by the prominence condensation. The reconnection flows are driven by the overlying reconnection and tether-cutting reconnection. The velocity of the reconnection flows increases from the quasi-static phase to the fast-rise phase, reaching several kilometers per second, which is similar to the speed of the field-aligned flows. We calculate the synthetic Doppler images by forward modeling and compare them with the observed LOS-oriented flows. The synthetic images show that the LOS-oriented flows of one ring with opposite internal flow driven by the field-aligned flows are identified in the simulation. And the synthetic images integrated along three different LOSs can resemble the observed direction reversal of the LOS-oriented flow in about 20 hr, when the included angle of two adjacent LOSs is about 10°. These results suggest that the observed LOS-oriented flows of one ring with an opposite internal flow may be explained by the LOS integration effect of field-aligned flows along different loops.

Keywords: Solar magnetic fields, Solar prominences, Solar magnetic reconnection, Magnetohydrodynamical simulations
G 68-34: A Double-lined M-dwarf Eclipsing Binary in a Hierarchical Triple System. Using high-resolution spectra from the Tillinghast Reflector Echelle Spectrograph and photometry from sector 56 of the Transiting Exoplanet Survey Satellite, we report that the nearby M dwarf G 68-34 is a double-lined eclipsing binary. The pair is spin-orbit synchronized with a period of 0.655 days. The light curve shows significant spot modulation with a larger photometric amplitude than that of the grazing eclipses. We perform a joint fit to the spectroscopic and photometric data, obtaining masses of 0.3280 ± 0.0034M ⊙ and 0.3207 ± 0.0036M ⊙ and radii of 0.345 ± 0.014R ⊙ and 0.342 ± 0.014R ⊙ after marginalizing over unknowns in the starspot distribution. This system adds to the small but growing population of fully convective M dwarfs with precisely measured masses and radii that can be used to test models of stellar structure. The pair also has a white-dwarf primary at 9″ separation, with the system known to be older than 5 Gyr from the white-dwarf cooling age. The binarity of G 68-34 confirms our hypothesis from Pass et al.: in that work, we noted that G 68-34 was both rapidly rotating and old, highly unusual given our understanding of the spin-down of M dwarfs, and that a close binary companion may be responsible.

Keywords: M dwarf stars, Starspots, Binary stars, Stellar radii, Spectroscopic binary stars, Stellar masses, Eclipsing binary stars
Alfvénic Motions Arising from Asymmetric Acoustic Wave Drivers in Solar Magnetic Structures. Alfvénic motions are ubiquitous in the solar atmosphere and their observed properties are closely linked to those of photospheric p-modes. However, it is still unclear how a predominantly acoustic wave driver can produce these transverse oscillations in the magnetically dominated solar corona. In this study we conduct a 3D ideal MHD numerical simulation to model a straight, expanding coronal loop in a gravitationally stratified solar atmosphere which includes a transition region and chromosphere. We implement a driver locally at one foot-point corresponding to an acoustic-gravity wave which is inclined by θ = 15° with respect to the vertical axis of the magnetic structure and is similar to a vertical driver incident on an inclined loop. We show that transverse motions are produced in the magnetic loop, which displace the axis of the waveguide due to the breaking of azimuthal symmetry, and study the resulting modes in the theoretical framework of a magnetic cylinder model. By conducting an azimuthal Fourier analysis of the perturbed velocity signals, the contribution from different cylindrical modes is obtained. Furthermore, the perturbed vorticity is computed to demonstrate how the transverse motions manifest themselves throughout the whole non-uniform space. Finally we present some physical properties of the Alfvénic perturbations and present transverse motions with velocity amplitudes in the range 0.2-0.75 km s-1 which exhibit two distinct oscillation regimes corresponding to 42 and 364 s, where the latter value is close to the period of the p-mode driver in the simulation.

Keywords: Solar atmosphere, Magnetohydrodynamics, Solar coronal loops, Solar coronal waves, Solar oscillations, Solar chromosphere, Magnetohydrodynamical simulations
Two Transient Quasi-periodic Oscillations in γ-Ray Emission from the Blazar S4 0954+658. In this work, we report periodicity search analyses in the gamma-ray light curve of the blazar S4 0954+658 in monitoring undertaken by the Fermi Large Area Telescope. Four analytical methods and a tool are adopted to detect any periodic flux modulation and corresponding significance level, revealing: (i) a quasi-periodic oscillation (QPO) of 66 days with a significance level of &gt;5σ spanning over 600 days from 2015 to 2016 (MJD 57,145-57,745), resulting in continuous observation of nine cycles, which is one of the longest cycles discerned in blazar gamma-ray light curves; (ii) a possible QPO of 210 days at a moderate significance of ~3.5σ, which lasted for over 880 days from 2020 to 2022 (MJD 59,035-59,915) and for four cycles. In addition, we discuss several physical models to explain the origin of the two transient QPOs and conclude that a geometrical scenario involving a plasma blob moving helically inside the jet can explain the timescale of the QPO.

Keywords: Blazars, Jets, Active galactic nuclei, Period search
A Machine Learning-Based Approach to Time-series Wave Identification in the Solar Wind. The Wind spacecraft has yielded several decades of high-resolution magnetic field data, a large fraction of which displays small-scale structures. In particular, the solar wind is full of wavelike fluctuations that appear in both the field magnitude and its components. The nature of these fluctuations can be tied to the properties of other structures in the solar wind, such as shocks, that have implications for the time evolution of the solar wind. As such, having a large collection of wave events would facilitate further study of the effects that these fluctuations have on solar wind evolution. Given the large volume of magnetic field data available, machine learning is the most practical approach to classifying the myriad small-scale structures observed. To this end, a subset of Wind data is labeled and used as a training set for a multibranch 1D convolutional neural network aimed at classifying circularly polarized wave modes. Using this algorithm, a preliminary statistical study of 1 yr of data is performed, yielding about 300,000 wave intervals out of about 5,000,000 solar wind intervals. The wave intervals come about more often in the fast solar wind and at higher temperatures, and the number of waves per day is highly periodic. This machine learning-based approach to wave detection has the potential to be a powerful, inexpensive way to catalog waves throughout decades of spacecraft data.

Keywords: Space plasmas, Neural networks, Space weather, Solar wind, Convolutional neural networks, Alfven waves, Interplanetary physics
The CGM<SUP>2</SUP> Survey: Quenching and the Transformation of the Circumgalactic Medium. This study addresses how the incidence rate of strong O VI absorbers in a galaxy's circumgalactic medium (CGM) depends on galaxy mass and, independently, on the amount of star formation in the galaxy. We use Hubble Space Telescope/Cosmic Origins Spectrograph absorption spectroscopy of quasars to measure O VI absorption within 400 projected kpc and 300 km s-1 of 52 galaxies with M * ~ 3 × 1010 M ⊙. The galaxies have redshifts 0.12 &lt; z &lt; 0.6, stellar masses 1010.1 M ⊙ &lt; M * &lt; 1010.9 M ⊙, and spectroscopic classifications as star-forming or passive. We compare the incidence rates of high column density O VI absorption (N O VI  ≥ 1014.3 cm-2) near star-forming and passive galaxies in two narrow ranges of stellar mass and, separately, in a matched range of halo mass. In all three mass ranges, the O VI covering fraction within 150 kpc is higher around star-forming galaxies than around passive galaxies with greater than 3σ-equivalent statistical significance. On average, the CGM of star-forming galaxies with M * ~ 3 × 1010 M ⊙ contains more O VI than the CGM of passive galaxies with the same mass. This difference is evidence for a CGM transformation that happens together with galaxy quenching and is not driven primarily by halo mass.

Keywords: Extragalactic astronomy, Quenched galaxies, Circumgalactic medium
A New Method Linking the Solar Wind Speed to the Coronal Magnetic Field. The release and acceleration of the solar wind is still an outstanding question. There are several aspects related to this phenomenon that still need to be investigated, and one of these is the identification of the region within the inner corona where the larger fraction of acceleration occurs. To address this matter, it is necessary to have reliable measurements of the solar wind speed between 1 and 10 solar radii (R ⊙). Moreover, in order to describe the coronal plasma behavior, it is important to consider its interaction with the magnetic field. Within this context, our intent is to investigate a method to combine measurements of the solar wind with the extrapolated magnetic field in the corona to derive how the solar wind velocity evolves along the magnetic field lines, aiming at better understanding the sources, origins, and acceleration of the solar wind. To this purpose, we used outflow speed measurements of the coronal plasma derived by applying the Doppler dimming technique, as well as the global magnetic field configuration derived from the measured photospheric magnetic field by using the Wang-Sheeley-Arge model. These two sets of data are then combined for heliocentric distances between 2.6 and 5 R ⊙. This paper presents the proposed method and the results obtained over two different Carrington rotations (CR 1923 and CR 1924), demonstrating the applicability of the method and the capability to link measured solar wind velocity to the extrapolated coronal magnetic field in order to derive the velocity profile.

Keywords: Solar corona, Solar wind, Solar magnetic fields
BICEP/Keck. XVII. Line-of-sight Distortion Analysis: Estimates of Gravitational Lensing, Anisotropic Cosmic Birefringence, Patchy Reionization, and Systematic Errors. We present estimates of line-of-sight distortion fields derived from the 95 and 150 GHz data taken by BICEP2, BICEP3, and the Keck Array up to the 2018 observing season, leading to cosmological constraints and a study of instrumental and astrophysical systematics. Cosmological constraints are derived from three of the distortion fields concerning gravitational lensing from large-scale structure, polarization rotation from magnetic fields or an axion-like field, and the screening effect of patchy reionization. We measure an amplitude of the lensing power spectrum ${A}_{L}^{\phi \phi }=0.95\pm 0.20$ . We constrain polarization rotation, expressed as the coupling constant of a Chern-Simons electromagnetic term g  a γ  ≤ 2.6 × 10-2/H  I , where H  I  is the inflationary Hubble parameter, and an amplitude of primordial magnetic fields smoothed over 1 Mpc B 1Mpc ≤ 6.6 nG at 95 GHz. We constrain the rms of optical depth fluctuations in a simple "crinkly surface" model of patchy reionization, finding A  τ  &lt; 0.19 (2σ) for the coherence scale of L  c  = 100. We show that all of the distortion fields of the 95 and 150 GHz polarization maps are consistent with simulations including lensed ΛCDM, dust, and noise, with no evidence for instrumental systematics. In some cases, the EB and TB quadratic estimators presented here are more sensitive than our previous map-based null tests at identifying and rejecting spurious B-modes that might arise from instrumental effects. Finally, we verify that the standard deprojection filtering in the BICEP/Keck data processing is effective at removing temperature to polarization leakage.

Keywords: Weak gravitational lensing, Primordial magnetic fields, Cosmic microwave background radiation, Observational cosmology, Reionization
Streams on FIRE: Populations of Detectable Stellar Streams in the Milky Way and FIRE. We present the first detailed comparison of populations of dwarf galaxy stellar streams in cosmological simulations and the Milky Way. In particular, we compare streams identified around 13 Milky Way analogs in the FIRE-2 simulations to streams observed by the Southern Stellar Stream Spectroscopic Survey (S 5). For an accurate comparison, we produce mock Dark Energy Survey (DES) observations of the FIRE streams and estimate the detectability of their tidal tails and progenitors. The number and stellar mass distributions of detectable stellar streams is consistent between observations and simulations. However, there are discrepancies in the distributions of pericenters and apocenters, with the detectable FIRE streams, on average, forming at larger pericenters (out to &gt;110 kpc) and surviving only at larger apocenters (≳40 kpc) than those observed in the Milky Way. We find that the population of high-stellar-mass dwarf galaxy streams in the Milky Way is incomplete. Interestingly, a large fraction of the FIRE streams would only be detected as intact satellites in DES-like observations, since their tidal tails have too low surface brightness to be detectable. We thus predict a population of yet-undetected tidal tails around Milky Way satellites, as well as a population of fully undetected low-surface-brightness stellar streams, and estimate their detectability with the Rubin Observatory. Finally, we discuss the causes and implications of the discrepancies between the stream populations in FIRE and the Milky Way, and explore future avenues for tests of satellite disruption in cosmological simulations.

Keywords: Stellar streams, Tidal disruption, Dwarf galaxies, Milky Way dynamics, Milky Way Galaxy, Astronomical simulations
Constraints on the IBEX Ribbon's Origin from Its Evolution over a Solar Cycle. In 2009, the Interstellar Boundary Explorer (IBEX) discovered a narrow "ribbon" of energetic neutral atom emissions across the sky with properties correlated with the solar wind latitudinal structure and the interstellar magnetic field draped around the heliosphere. It is widely believed that the ribbon is formed from the escape of heliospheric ENAs into the local interstellar medium and their eventual return as secondary ENAs. However, there is no consensus on the rate of pitch angle scattering of these PUIs before they become secondary ENAs. We test two opposing limits of scattering rates ("weak" versus "strong") by solving a time-dependent model of the ribbon that evolves with the solar cycle, and we compare them to IBEX observations over 2009-2019. First, we find that both models qualitatively reproduce the evolution of IBEX fluxes for most of the data set, with a few exceptions, although the strong (or "spatial retention") scattering model greatly underestimates the observed fluxes. Regardless, time dependence of fluxes cannot distinguish these models. Second, the ribbon's geometric properties, i.e., its center and radius, are significantly different between the models. The spatial retention model reproduces the observed ribbon centers as a function of energy and time slightly better than the weak scattering model, and the spatial retention model reproduces the observed ribbon radius over energy and time almost perfectly, whereas the weak scattering model compares poorly. Our analysis favors the spatial retention mechanism as the source of the IBEX ribbon, but it requires modification to increase the flux of ENAs observed at 1 au.

Keywords: Solar cycle, Space plasmas, Heliosphere, Solar wind, Interstellar magnetic fields, Pickup ions