Sazuna/UAT_keywords huggingface dataset:
Reconstruction of Photospheric Velocity Fields from Highly Corrupted Data. The analysis of the photospheric velocity field is essential for understanding plasma turbulence in the solar surface, which may be responsible for driving processes such as magnetic reconnection, flares, wave propagation, particle acceleration, and coronal heating. Currently, the only available methods to estimate velocities at the solar photosphere transverse to an observer's line of sight infer flows from differences in image structure in successive observations. Due to data noise, algorithms such as local correlation tracking may lead to a vector field with wide gaps where no velocity vectors are provided. In this paper, a novel method for image inpainting of highly corrupted data is proposed and applied to the restoration of horizontal velocity fields in the solar photosphere. The restored velocity field preserves all the vector field components present in the original field. The method shows robustness when applied to both simulated and observational data.

Keywords: Space plasmas, Magnetohydrodynamics, Solar photosphere, Computational methods, Astrophysical fluid dynamics
Influence of Spontaneous Fission Rates on the r-process Nucleosynthesis. The effects of spontaneous fission on r-process nucleosynthesis are investigated in the hot wind r-process scenario. We perform network calculations using three sets of spontaneous fission rates to study how the abundance pattern is shaped when different sets of fissioning nuclei are encountered by the r-process nuclear flow. The relative contributions from spontaneous fission, neutron-induced fission, and β-delayed fission to the nucleosynthesis process are studied by calculating the corresponding fission flow. We show that the relative contributions of various fission channels in r-process nucleosynthesis depend on the astrophysical conditions and fission models used. By using the spontaneous fission rates from a modified Swiatecki's formula with isospin and blocking effects, the spontaneous fission and neutron-induced fission play an equally important role in r-process nucleosynthesis under an extreme neutron-rich astrophysical scenario with Y  e  = 0.1. The fissioning nuclei are located in different regions of the nuclear chart when different spontaneous fission models are used. The fission fragment distributions of fissioning nuclei in different regions have apparent diversity, which affects the mass regions where fission products are deposited, leading to the difference of the final abundance around the second r-process peak and rare-earth subpeak.

Keywords: R-process, Nucleosynthesis
FAST Search for Circumstellar Atomic Hydrogen. I. The Young Planetary Nebula IC 4997. Using the Five-hundred-meter Aperture Spherical radio Telescope in Guizhou, China, we detect the 21 cm neutral atomic hydrogen absorption in the young planetary nebula IC 4997. The absorption arises from a shell that is also associated with Na I D lines. The H I shell has a mass of 1.46 × 10-2 M ⊙ and a dynamic age of 990 yr. The column density of H I is estimated to be 7.1 × 1020 cm-2, which can be well explained in terms of a photodissociation region around the ionized nebula, limited by the self-shielding of H2. We find that the atomic-to-ionized hydrogen ratio is 0.6, suggesting that H I substantially contributes to the overall nebular mass.

Keywords: Circumstellar envelopes, Planetary nebulae, Single-dish antennas, Stellar mass loss
Modeling the Optical to Ultraviolet Polarimetric Variability from Thomson Scattering in Colliding-wind Binaries. Massive-star binaries are critical laboratories for measuring masses and stellar wind mass-loss rates. A major challenge is inferring viewing inclination and extracting information about the colliding-wind interaction (CWI) region. Polarimetric variability from electron scattering in the highly ionized winds provides important diagnostic information about system geometry. We combine for the first time the well-known generalized treatment of Brown et al. for variable polarization from binaries with the semianalytic solution for the geometry and surface density CWI shock interface between the winds based on Cantó et al. Our calculations include some simplifications in the form of inverse-square law wind densities and the assumption of axisymmetry, but in so doing they arrive at several robust conclusions. One is that when the winds are nearly equal (e.g., O+O binaries) the polarization has a relatively mild decline with binary separation. Another is that despite Thomson scattering being a gray opacity, the continuum polarization can show chromatic effects at ultraviolet wavelengths but will be mostly constant at longer wavelengths. Finally, when one wind dominates the other, as, for example, in WR+OB binaries, the polarization is expected to be larger at wavelengths where the OB component is more luminous and generally smaller at wavelengths where the WR component is more luminous. This behavior arises because, from the perspective of the WR star, the distortion of the scattering envelope from spherical is a minor perturbation situated far from the WR star. By contrast, the polarization contribution from the OB star is dominated by the geometry of the CWI shock.

Keywords: Massive stars, Stellar winds, Spectropolarimetry
Methanol-A Poor Biosignature Gas in Exoplanet Atmospheres. Biosignature gas research has been growing in recent years thanks to next-generation space- and ground-based telescopes. Methanol (CH3OH) has many advantages as a biosignature gas candidate. First, CH3OH's hydroxyl group (OH) has a unique spectral feature not present in other anticipated gases in the atmospheres of rocky exoplanets. Second, there are no significant known abiotic CH3OH sources on terrestrial planets in the solar system. Third, life on Earth produces CH3OH in large quantities. However, despite CH3OH's advantages, we consider it a poor biosignature gas in the atmospheres of terrestrial exoplanets due to the enormous production flux required to reach its detection limit. CH3OH's high water solubility makes it very difficult to accumulate in the atmosphere. For the highly favorable planetary scenario of an exoplanet with an H2-dominated atmosphere orbiting an M5V dwarf star, we find that only when the column-averaged mixing ratio of CH3OH reaches at least 10 ppm can we detect it with the James Webb Space Telescope (JWST). The CH3OH bioproduction flux required to reach the JWST detection threshold of 10 ppm must be of the order of 1014 molecules cm-2 s-1, which is roughly three times the annual O2 production on Earth. Considering that such an enormous flux of CH3OH is essentially a massive waste of organic carbon-a major building block of life, we think this flux, while mathematically possible, is likely biologically unattainable. Although CH3OH can theoretically accumulate on exoplanets with CO2- or N2-dominated atmospheres, such planets' small atmospheric scale heights and weak atmospheric signals put them out of reach for near-term observations.

Keywords: Biosignatures, Astrobiology, Exoplanet atmospheres
Photosphere Recession and Luminosity of Homologous Explosions Revisited. By assuming the photosphere located at the outmost edge of the ejecta, Arnett et al. (1980, 1982, 1989) presented the light curves of homologous explosions in supernovae analytically and numerically to include recombination effects. Actually as homologous expansion proceeds, the photosphere recedes deeper into the ejecta. In this situation, the photosphere radius increases at early times and decreases later on, which can be described by a simple method proposed by Liu et al. To study how the photosphere recession affects the luminosity evolution, we impose a boundary condition on the photosphere to determine the spatial and time distribution of the temperature of the ejecta, which is clarified to be reasonable. We find that the photosphere recession reduces the luminosity compared with the previous result without the recession, which can be tested with observations of Type-IIP supernovae.

Keywords: Core-collapse supernovae
Infrared Line Emissions from Atoms and Atomic Ions in NGC 7027: Improved Wavelength Determinations for Infrared Metal Lines and a Probable Detection of Zn<SUP>5+</SUP>. An infrared L- and M-band spectral survey, performed toward the young planetary nebula NGC 7027 with the iSHELL instrument on NASA's Infrared Telescope Facility (IRTF), has revealed more than 20 vibrational lines of the molecules HeH+, H2, and CH+ and more than 50 spectral lines of atoms and atomic ions. The present paper focuses on the atomic line emissions, the molecular lines having been discussed in two previous publications. The atomic lines detected with high confidence in the 2.951-5.24 μm region covered (incompletely) by this survey comprise (1) six collisionally excited lines of metal ions that had previously been identified in astrophysical nebulae but for which the present observations provide the most accurate wavelength determinations obtained to date; (2) a spectral line at 4.6895 μm, not previously reported, for which the probable identification is the 4 F 7/2-4 F 9/2 fine-structure transition of [Zn VI]; (3) 39 recombination lines of H and He+, with upper states of principal quantum number up to 38 (H) or 24 (He+); (4) 10 recombination lines of the multielectron species He, C2+, and C3+.

Keywords: Infrared astronomy, Atomic spectroscopy, Planetary nebulae, Interstellar line emission
Groups and Protocluster Candidates in the CLAUDS and HSC-SSP Joint Deep Surveys. Using the extended halo-based group finder developed by Yang et al., which is able to deal with galaxies via spectroscopic and photometric redshifts simultaneously, we construct galaxy group and candidate protocluster catalogs in a wide redshift range (0 &lt; z &lt; 6) from the joint CFHT Large Area U-band Deep Survey and Hyper Suprime-Cam Subaru Strategic Program deep data set. Based on a selection of 5,607,052 galaxies with i-band magnitude m  i  &lt; 26 and a sky coverage of 34.41 deg2, we identify a total of 2,232,134 groups, of which 402,947 groups have at least three member galaxies. We have visually checked and discussed the general properties of these richest groups at redshift z &gt; 2.0. By checking the galaxy number distributions within a 5–7 h ‑1Mpc projected separation and a redshift difference Δz ≤ 0.1 around those richest groups at redshift z &gt; 2, we identify lists of 761, 343, and 43 protocluster candidates in the redshift bins 2 ≤ z &lt; 3, 3 ≤ z &lt; 4, and z ≥ 4, respectively. In general, these catalogs of galaxy groups and protocluster candidates will provide useful environmental information in probing galaxy evolution along cosmic time.

Keywords: Galaxy clusters, Galaxy dark matter halos, Dark matter distribution, Large-scale structure of the universe, Protoclusters, Galaxy groups, Galaxy evolution, Dark matter, Galaxies
VERTICO II: How H I-identified Environmental Mechanisms Affect the Molecular Gas in Cluster Galaxies. In this VERTICO early science paper we explore in detail how environmental mechanisms, identified in H I, affect the resolved properties of molecular gas reservoirs in cluster galaxies. The molecular gas is probed using ALMA ACA (+TP) observations of 12CO(2-1) in 51 spiral galaxies in the Virgo cluster (of which 49 are detected), all of which are included in the VIVA H I survey. The sample spans a stellar mass range of $9\leqslant \mathrm{log}\,{M}_{\star }/{M}_{\odot }\leqslant 11$ . We study molecular gas radial profiles, isodensity radii, and surface densities as a function of galaxy H I deficiency and morphology. There is a weak correlation between global H I and H2 deficiencies, and resolved properties of molecular gas correlate with H I deficiency: galaxies that have large H I deficiencies have relatively steep and truncated molecular gas radial profiles, which is due to the removal of low-surface-density molecular gas on the outskirts. Therefore, while the environmental mechanisms observed in H I also affect molecular gas reservoirs, there is only a moderate reduction of the total amount of molecular gas.

Keywords: Galaxy clusters, Molecular gas, Galaxy environments, Virgo Cluster, Galaxy evolution, Interstellar medium, Galaxies
High-resolution ALMA Study of CO J = 2-1 Line and Dust Continuum Emissions in Cluster Galaxies at z = 1.46. We present new Atacama Large Millimeter/submillimeter Array (ALMA) results obtained from spatially resolved CO J = 2-1 line (0.″4 resolution) and 870 μm continuum (0.″2 resolution) observations of cluster galaxies in XMMXCS J2215.9-1738 at z = 1.46. Our sample comprises 17 galaxies within ~0.5 Mpc (0.6R 200) of the cluster center, all of which have previously been detected in the CO J = 2-1 line at a lower resolution. The effective radii of both the CO J = 2-1 line and 870 μm dust continuum emissions are robustly measured for nine galaxies by modeling the visibilities. We find that the CO J = 2-1 line emission in all of the nine galaxies is more extended than the dust continuum emission by a factor of 2.8 ± 1.4. We investigate the spatially resolved Kennicutt-Schmidt (KS) relation in two regions within the interstellar medium of the galaxies. The relation for our sample reveals that the central region (0 &lt; r &lt; R  e,870μm) of galaxies tends to have a shorter gas depletion timescale, i.e., a higher star formation efficiency, compared to the extended region (R  e,870μm &lt; r &lt; R  e,CO). Overall, our result suggests that star formation activities are concentrated inside the extended gas reservoir, possibly resulting in the formation of a bulge structure. We find consistency between the ALMA 870 μm radii of star-forming members and the Hubble Space Telescope/1.6 μm radii of passive members in a mass-size distribution, which suggests a transition from star-forming to passive members within ~0.5 Gyr. In addition, no clear differences in the KS relation nor in the sizes are found between galaxies with and without a close companion.

Keywords: High-redshift galaxy clusters, Galaxy structure, Star formation, Galaxy evolution, Interstellar medium, High-redshift galaxies
Bipolar Ephemeral Active Regions, Magnetic Flux Cancellation, and Solar Magnetic Explosions. We examine the cradle-to-grave magnetic evolution of 10 bipolar ephemeral active regions (BEARs) in solar coronal holes, especially aspects of the magnetic evolution leading to each of 43 obvious microflare events. The data are from the Solar Dynamics Observatory: 211 Å coronal EUV images and line-of-sight photospheric magnetograms. We find evidence that (1) each microflare event is a magnetic explosion that results in a miniature flare arcade astride the polarity inversion line (PIL) of the explosive lobe of the BEAR's anemone magnetic field; (2) relative to the BEAR's emerged flux-rope Ω loop, the anemone's explosive lobe can be an inside lobe, an outside lobe, or an inside-and-outside lobe; (3) 5 events are confined explosions, 20 events are mostly confined explosions, and 18 events are blowout explosions, which are miniatures of the magnetic explosions that make coronal mass ejections (CMEs); (4) contrary to the expectation of Moore et al., none of the 18 blowout events explode from inside the BEAR's Ω loop during the Ω loop's emergence; and (5) before and during each of the 43 microflare events, there is magnetic flux cancellation at the PIL of the anemone's explosive lobe. From finding evident flux cancellation at the underlying PIL before and during all 43 microflare events-together with BEARs evidently being miniatures of all larger solar bipolar active regions-we expect that in essentially the same way, flux cancellation in sunspot active regions prepares and triggers the magnetic explosions for many major flares and CMEs.

Keywords: Jets, Solar magnetic reconnection, Solar magnetic flux emergence, Solar active regions, Solar magnetic fields, Ephemeral active regions, Solar coronal holes
Disks in Nearby Young Stellar Associations Found Via Virtual Reality. The Disk Detective citizen science project recently released a new catalog of disk candidates found by visual inspection of images from NASA's Wide-field Infrared Survey Explorer mission and other surveys. We applied this new catalog of well-vetted disk candidates to search for new members of nearby young stellar associations (YSAs) using a novel technique based on Gaia data and virtual reality (VR). We examined AB Doradus, Argus, β Pictoris, Carina, Columba, Octans-Near, Tucana-Horologium, and TW Hya by displaying them in VR together with other nearby stars, color coded to show infrared excesses found via Disk Detective. Using this method allows us to find new association members in mass regimes where isochrones are degenerate. We propose 10 new YSA members with infrared excesses: three of AB Doradus (HD 44775, HD 40540 and HD 44510), one of β Pictoris (HD 198472), two of Octans-Near (HD 157165 and BD+35 2953), and four disk-hosting members of a combined population of Carina, Columba, and Tucana-Horologium: CPD-57 937, HD 274311, HD 41992, and WISEA J092521.90-673224.8. This last object (J0925) appears to be an extreme debris disk with a fractional infrared luminosity of 3.7 × 10-2. We also propose two new members of AB Doradus that do not show infrared excesses: TYC 6518-1857-1 and CPD-25 1292. We find HD 15115 appears to be a member of Tucana-Horologium rather than β Pictoris. We advocate for membership in Columba-Carina of HD 30447, CPD-35 525, and HD 35841. Finally, we propose that three M dwarfs, previously considered members of Tucana-Horologium are better considered a separate association, tentatively called "Smethells 165".

Keywords: Infrared excess, Moving clusters, Debris disks
Bumpy Declining Light Curves Are Common in Hydrogen-poor Superluminous Supernovae. Recent work has revealed that the light curves of hydrogen-poor (Type I) superluminous supernovae (SLSNe), thought to be powered by magnetar central engines, do not always follow the smooth decline predicted by a simple magnetar spin-down model. Here we present the first systematic study of the prevalence and properties of "bumps" in the post-peak light curves of 34 SLSNe. We find that the majority (44%-76%) of events cannot be explained by a smooth magnetar model alone. We do not find any difference in supernova properties between events with and without bumps. By fitting a simple Gaussian model to the light-curve residuals, we characterize each bump with an amplitude, temperature, phase, and duration. We find that most bumps correspond with an increase in the photospheric temperature of the ejecta, although we do not see drastic changes in spectroscopic features during the bump. We also find a moderate correlation (ρ ≍ 0.5; p ≍ 0.01) between the phase of the bumps and the rise time, implying that such bumps tend to happen at a certain "evolutionary phase," (3.7 ± 1.4)t rise. Most bumps are consistent with having diffused from a central source of variable luminosity, although sources further out in the ejecta are not excluded. With this evidence, we explore whether the cause of these bumps is intrinsic to the supernova (e.g., a variable central engine) or extrinsic (e.g., circumstellar interaction). Both cases are plausible, requiring low-level variability in the magnetar input luminosity, small decreases in the ejecta opacity, or a thin circumstellar shell or disk.

Keywords: Circumstellar matter, Supernovae, Circumstellar shells, Magnetars
Statistical Study of the Kinetic Features of Supra-arcade Downflows Detected from Multiple Solar Flares. We have developed a tracking algorithm to determine the speeds of supra-arcade downflows (SADs) and set up a system to automatically track SADs and measure some interesting parameters. By conducting an analysis of six flares observed by the Atmospheric Imaging Assembly on the Solar Dynamics Observatory, we detect more smaller and slower SADs than prior work, due to the higher spatial resolution of our observational data. The inclusion of these events with smaller and slower SADs directly results in lower median velocities and widths than in prior work, but the fitted distributions and evolutions of the parameters still show good consistency with prior work. The observed distributions of the widths, speeds, and lifetimes of SADs are consistent with log-normal distributions, indicating that random and unstable processes are responsible for generating SADs during solar eruptions. Also, we find that the fastest SADs occur at approximately the middle of the height ranges. The number of SADs in each image versus time shows that there are "rest phases" of SADs, when few SADs are seen. These findings support the idea that SADs originate from a fluid instability. We compare our results with a numerical simulation that generates SADs using a mixture of the Rayleigh-Taylor instability and the Richtmyer-Meshkov instability, and find that the simulation generates quantities that are consistent with our observational results.

Keywords: Solar activity, Solar flares
Orbital Dynamics and Extreme Scattering Event Properties from Long-term Scintillation Observations of PSR J1603-7202. We model long-term variations in the scintillation of binary pulsar PSR J1603-7202, observed by the 64 m Parkes radio telescope (Murriyang) between 2004 and 2016. We find that the time variation in the scintillation arc curvature is well-modeled by scattering from an anisotropic thin screen of plasma between the Earth and the pulsar. Using our scintillation model, we measure the inclination angle and longitude of ascending node of the orbit, yielding a significant improvement over the constraints from pulsar timing. From our measurement of the inclination angle, we place a lower bound on the mass of J1603-7202's companion of ≳0.5 M ⊙ assuming a pulsar mass of ≳1.2 M ⊙. We find that the scintillation arcs are most pronounced when the electron column density along the line of sight is increased, and that arcs are present during a known extreme scattering event. We measure the distance to the interstellar plasma and its velocity, and we discuss some structures seen in individual scintillation arcs within the context of our model.

Keywords: Interstellar scintillation, Orbit determination, Interstellar medium, Millisecond pulsars
Are Binary Black Hole Mergers and Long Gamma-Ray Bursts Drawn from the Same Black Hole Population?. This paper compares the population of binary black hole (BBH) mergers detected by LIGO/Virgo with selected long gamma-ray burst (GRB) world models convolved with a delay function (LGRBs are used as a tracer of stellar-mass BH formation). The comparison involves the redshift distribution and the fraction of LGRBs required to produce the local rate of BBH mergers. We find that BBH mergers and LGRBs cannot have the same formation history, unless BBH mergers have a long coalescence time of several Gyr. This would imply that BHs born during the peak of long GRB formation at redshift z ≈ 2-3 merge within the horizon of current GW interferometers. We also show that LGRBs are more numerous than BBH mergers, meaning that most of them do not end their lives in BBH mergers. We interpret these results as an indication that BBH mergers and LGRBs constitute two distinct populations of stellar-mass BHs, with LGRBs being more frequent than BBH mergers. We speculate that the descendants of LGRBs may resemble galactic high-mass X-ray binaries more than BBH mergers. Finally, we discuss the possible existence of a subpopulation of fast-spinning LGRB descendants among BBH mergers, showing that this population, if it exists, is expected to become dominant beyond redshift z ≈ 1, leading to a change in the observed properties of BBH mergers.

Keywords: Gravitational wave sources, Gamma-ray bursts, Astrophysical black holes