Sazuna/UAT_keywords huggingface dataset:
The Evolution of the Size and Merger Fraction of Submillimeter Galaxies across 1 &lt; z ≲ 6 as Observed by JWST. Precise tracking of the growth in galaxy size and the evolution of merger fractions with redshift is vital for understanding the formation history of submillimeter galaxies (SMGs). This study investigates this evolution over a broad redshift range (1 &lt; z ≲ 6) using a sample of 222 SMGs with a median redshift of   identified by the Atacama Large Millimeter/submillimeter Array and the James Clerk Maxwell Telescope, enhanced by the advanced imaging capabilities of the JWST/NIRCam and MIRI. We find significant evolution in effective radii (Re) in the rest-frame V band (Re ∝ (1 + z)‑0.87 ± 0.08) and near-infrared (NIR) band (Re ∝ (1 + z)‑0.88 ± 0.11), with the NIR size evolution resembling that of massive star-forming galaxies (SFGs) at lower redshift. Visual inspections reveal a major merger fraction of 24.3% ± 3.7% and an interaction fraction of up to 48.4% ± 11.1%. The major merger fraction exhibits an increase from 14.7% ± 9.1% at z = 1 to 26.6% ± 8.4% at z = 3, after which it remains approximately constant across the redshift range 3 &lt; z &lt; 6. In contrast, the interaction fraction remains relatively stable across the range 2 &lt; z &lt; 5. Our results indicate that late-stage major mergers are not the primary formation mechanism for SMGs at z &lt; 3, while interactions appear to play a significant role across the broader redshift range of 1 &lt; z &lt; 6. Additionally, Hubble Space Telescope–based major merger identifications may overestimate the true fraction by a factor of 1.7 at z ∼ 2. These findings highlight the varying roles of mergers and interactions in driving the formation of massive, dusty SFGs across different redshifts.

Keywords: Galaxy structure, High-redshift galaxies, Galaxy mergers, Luminous infrared galaxies
Stellar Evolution Along the Asymptotic Giant Branch as Revealed by the Shape of Miras' Visual Light Curves. A new analysis of a sample of visual light curves of Mira variables is presented. The curves cover the past four decades and are selected from the AAVSO database as including a large number of high-density observations. The aim is to offer a more quantitative and more systematic picture than available from earlier studies. The results corroborate earlier descriptions and reveal new correlations between the shapes of the light curves and the evolution of the star along the asymptotic giant branch (AGB). A family of nearly sinusoidal curves associated with M spectral types and displaying no sign of having experienced third-dredge-up events is identified with confidence. A detailed study of its properties is presented and used to suggest possible interpretations. All other curves are distinct from this family and start departing from it by displaying a broader luminosity minimum, progressively taking the form of a hump climbing the ascending branch. Possible relations between such progression and the evolution of the star along the AGB are discussed. New correlations between parameters defining the shape of the light curve and the state of the star are revealed; while the average trend is established with confidence, deviations from it cause a significant scatter of the parameters of the curves. Comments aimed at shedding light on the underlying physics are presented together with speculative interpretations, in the hope that they could encourage and inspire new studies, in particular based on models of the inner star dynamics.

Keywords: Light curves, Asymptotic giant branch stars, Mira variable stars, Late stellar evolution
Determining the Polarization of a Coronal Standing Kink Oscillation Using Spectral Imaging Techniques with CoMP. Coronal oscillations offer insight into energy transport and driving in the solar atmosphere. Knowing its polarization state helps constrain a wave's displacement and velocity amplitude, improving estimates of wave energy flux and deposition rate. We demonstrate a method to combine imaging and spectral data to infer the polarization of a coronal loop's standing kink wave, without the need for multiple instruments or multiple lines of sight. We use the unique capabilities of the Coronal Multi-channel Polarimeter (CoMP) to observe the standing kink mode of an off-limb coronal loop perturbed by an eruption. The full off-disk corona is observed using the 1074 nm Fe XIII spectral line, providing Doppler velocity, intensity, and line width. By tracking the oscillatory motion of a loop apex in a time–distance map, we extract the line-of-sight (Doppler) velocity of the inhomogeneity as it sways and compare it with the derivative of its plane-of-sky displacement. This analysis provides the loop's velocity in two perpendicular planes as it oscillates with a period of   minutes. Through detailed analysis of the phase relation between the transverse velocities, we infer the kink oscillation to be horizontally polarized, oscillating in a plane tilted   away from the plane of sky. The line widths show a periodic enhancement during the kink oscillation, exhibiting both the kink period and its double. This study is the first to combine direct imaging and spectral data to infer the polarization of a coronal loop oscillation from a single viewpoint.

Keywords: Solar oscillations, Active solar corona, Solar coronal seismology, Infrared spectroscopy
The Host Galaxy of FRB 20190520B and Its Unique Ionized Gas Distribution. The properties of host galaxies associated with fast radio bursts (FRBs) provide critical information for inferring the progenitors and radiation mechanisms of these bursts. We report on the host galaxy of the repeating FRB 20190520B, a dwarf galaxy at the spectroscopic redshift z = 0.241 with a stellar mass of (6.2 ± 0.8) × 108 M ⊙. The emission-line ratios suggest that the ionized gas is powered by star formation. The total Hα-traced star formation rate (SFR) is 0.70 ± 0.01 M ⊙ yr‑1, and the metallicity is  12+log10([O/H])≥7.4±0.1 . The specific star formation rate (sSFR) is  logsSFR/yr‑1=‑9.0±0.1 , higher than the upper limit of ‑9.4 observed in nearby dwarf galaxies. The dispersion measure (DM) contribution from the host galaxy is estimated to be DMhost ≈ 950 ± 220 pc cm‑3, based on the Hα emission. The FRB and the associated persistent radio source are located at the Hα emission peak, offset by ∼1 .' 4 (5.5 kpc) in projection from the stellar continuum. At this position, the lower limit of  logsSFR/yr‑1  is ‑8.5 ± 0.1, more than 3 times the galaxy's total sSFR. The Hα velocity difference between the stellar continuum and the offset gas is 39.6 ± 0.4 km s‑1, which is sufficient to draw conclusions about the nature of the offset.

Keywords: Starburst galaxies, Dwarf galaxies, Radio transient sources
Three-dimensional Structure of Incomplete Carbon–Oxygen Detonations in Type Ia Supernovae. Carbon–oxygen (CO) detonation with reactions terminating either after burning of 12C in the leading 12C + 12C reaction or after burning of 12C and 16O to Si-group elements may occur in the low-density outer layers of exploding white dwarfs and be responsible for the production of intermediate-mass elements observed in the outer layers of Type Ia supernovae. Basic one-dimensional properties of CO-detonations have been summarized in our previous work. This paper presents the results of two- and three-dimensional numerical simulations of low-density CO-detonations and discusses their multidimensional stability, cellular structure, and propagation through a constant low-density background. We find three-dimensional CO detonations to be strikingly different from their one-dimensional and two-dimensional counterparts. Three-dimensional detonations are significantly more robust and capable of propagating without decay compared to highly unstable and marginal one- and two-dimensional detonations. The detonation cell size and whether burning of 12C in a three-dimensional detonation wave is followed by the subsequent 16O burning are sensitive to both the background density and the initial 12C to 16O mass ratio. We also discuss the possible implications for understanding the observed early-time bumps in light curves.

Keywords: Type Ia supernovae
Four Sub-Earth Planets Orbiting Barnard's Star from MAROON-X and ESPRESSO. Barnard's Star is an old, single M dwarf star that comprises the second-closest extrasolar system. It has a long history of claimed planet detections from both radial velocities and astrometry. However, none of these claimed detections have so far withstood further scrutiny. Continuing this story, extreme precision radial velocity measurements from the ESPRESSO instrument have recently been used to identify four new sub-Earth-mass planet candidates around Barnard's Star. We present here 112 radial velocities of Barnard's Star from the MAROON-X instrument that were obtained independently to search for planets around this compelling object. The data have a typical precision of 30 cm s−1 and are contemporaneous with the published ESPRESSO measurements (2021─2023). The MAROON-X data on their own confirm planet b (P = 3.154 days) and planet candidates c and d (P = 4.124 and 2.340 days, respectively). Furthermore, adding the MAROON-X data to the ESPRESSO data strengthens the evidence for planet candidate e (P = 6.739 days), thus leading to its confirmation. The signals from all four planets are &lt;50 cm s−1, the minimum masses of the planets range from 0.19 to 0.34 M⊕, and the system is among the most compact known among late M dwarfs hosting low-mass planets. The current data rule out planets with masses &gt;0.57 M⊕ (with a 99% detection probability) in Barnard's Star's habitable zone (P = 10─42 days).

Keywords: Radial velocity, Exoplanets, Spectroscopy
Examining the Potential for Methyl Halide Accumulation and Detectability in Possible Hycean-type Atmospheres. Some sub-Neptune planets may host habitable conditions; for example "Hycean" worlds with H2 envelopes over liquid water oceans can maintain potentially hospitable pressures and temperatures at their surface. Recent JWST observations of K2-18b and TOI-270d have shown that such worlds could be compelling targets for biosignature searches, given their extended scale heights and therefore large atmospheric signatures. Methylated biosignatures, a broad group of gases that can be generated by biological attachment of a CH3 group to an environmental substrate, have been proposed as candidate signs of life for Earth-like exoplanets. However, methyl halides (CH3 + halogen) have not yet been robustly examined with self-consistent photochemical and spectral models for planets with H2-dominated atmospheres. Here we demonstrate that methyl chloride (CH3Cl), predominantly produced by marine microbes, could be detected using JWST in tens of transits or fewer for Hycean planets, comparable to detection requirements for other potential atmospheric biosignatures. The threshold atmospheric mixing ratio for detectability is ∼10 ppm, which can accumulate with global fluxes comparable to moderately productive local environments on Earth.

Keywords: Exoplanet atmospheric composition , Biosignatures, Astrobiology, Exoplanet atmospheres
Andromeda XXXV: The Faintest Dwarf Satellite of the Andromeda Galaxy. We present the discovery of Andromeda XXXV, the faintest Andromeda satellite galaxy discovered to date, identified as an overdensity of stars in the Pan-Andromeda Archaeological Survey and confirmed via Hubble Space Telescope imaging. Located at a heliocentric distance of   kpc and   kpc from Andromeda, Andromeda XXXV is an extended (  pc), elliptical (ϵ = 0.4 ± 0.2), metal-poor ([Fe/H] ∼ ‑1.9) system, and the least luminous (MV = ‑5.2 ± 0.3) of Andromeda's dwarf satellites discovered so far. Andromeda XXXV's properties are consistent with the known population of dwarf galaxies around the Local Group, bearing close structural resemblance to the Canes Venatici II and Hydra II Milky Way (MW) dwarf satellite galaxies. Its stellar population, characterized by a red horizontal branch or a red clump feature, mirrors that of other Andromeda satellite galaxies in showing evidence for a spread in age and metallicity, with no signs of younger stellar generations. This age–metallicity spread is not observed in MW satellites of comparable stellar mass, and highlights the persistent differences between the satellite systems of Andromeda and the MW, extending even into the ultrafaint regime.

Keywords: Dwarf galaxies, Andromeda Galaxy
Meridional Circulation. I. A Formation Channel for Lithium-rich and Super-lithium-rich Red Clump Stars. Current observations indicate that stars with higher rotation rates appear to maintain more surface lithium, and the majority of lithium-rich giants are indeed red clump stars. Hence, we investigate the mechanisms behind lithium enrichment in rotating red clump stars and the pathways to forming lithium-rich red clump stars. Meridional circulation is prevalent in the radiative zone of rotating giants. We model its radial mixing as a diffusion process and derive the corresponding diffusion coefficient based on its material transfer effect. Due to uncertainties in numerical calculations, we consider an average diffusion effect. Additionally, certain limiting conditions for the radial velocity of meridional circulation are incorporated. With varying input rotation velocities, we simulate the lithium evolution for red clump stars with this model. Our results indicate that the material transfer effect due to meridional circulation can efficiently transport beryllium, produced by H burning, into the convective envelope. This meridional circulation can lead to lithium enrichment, with a maximum lithium abundance increment approaching 3.0 dex. Consequently, it is capable of forming both lithium-rich and super-lithium-rich red clump stars. The degree of lithium enrichment exhibits a strong positive correlation with the rotation velocity, i.e., faster red clump stars show more surface lithium. Furthermore, our models indicate that lithium-rich red clump stars are relatively young (∼106 yr), which aligns with observation evidence.

Keywords: Red giant clump, Stellar abundances, Low mass stars, Lithium stars, Stellar rotation, Stellar evolution
XRISM Reveals Low Nonthermal Pressure in the Core of the Hot, Relaxed Galaxy Cluster A2029. We present XRISM Resolve observations of the core of the hot, relaxed galaxy cluster Abell 2029 (A2029). We find that the line-of-sight bulk velocity of the intracluster medium (ICM) within the central 180 kpc is at rest with respect to the brightest cluster galaxy, with a 3σ upper limit of ∣vbulk∣ &lt; 100 km s−1. We robustly measure the field-integrated ICM velocity dispersion to be σv = 169 ± 10 km s−1, obtaining similar results for both single-temperature and two-temperature plasma models to account for the cluster cool core. This result, if ascribed to isotropic turbulence, implies a subsonic ICM with Mach number   and a nonthermal pressure fraction of 2.6 ± 0.3%. The turbulent velocity is similar to what was measured in the core of the Perseus cluster by Hitomi, but here in a more massive cluster with an ICM temperature of 7 keV, the limit on the nonthermal pressure fraction is even more stringent. Our result is consistent with expectations from simulations of relaxed clusters, but it is on the low end of the predicted distribution, indicating that A2029 is an exceptionally relaxed cluster with no significant impacts from either a recent minor merger or active galactic nucleus activity.

Keywords: Galaxy clusters, High resolution spectroscopy, Intracluster medium
Spatially Resolved Oscillations of a Flare Looptop X-Ray Source. The looptop region in solar flares is a crucial site to understand the physical processes of magnetic reconnection and particle acceleration. Here, we report novel details of a flare looptop X-ray source that is associated with electron acceleration. The looptop source exhibits an oscillation in height that is statistically anticorrelated with the X-ray intensity, in which the variation in intensity slightly precedes the height. Two oscillation periods are found, i.e., a period of ∼2 minutes with a large amplitude and a relatively weak period of ∼1 minute. The nonthermal electron spectral index and flux deduced from X-ray spectra, and the intensity of flare ribbons/footpoints seen in EUV/UV images all show similar oscillations. In addition, the repeated downward contracting loops/plasmoids from the reconnection current sheet are observed. These observations strongly support a physical scenario where repeated reconnection outflows impinge on the flare looptop, while concurrently accelerated electrons are also quasiperiodically injected into it. These energy inputs (bulk flow and electron beams) subsequently produce oscillations in the looptop X-ray source, and cause brightness fluctuations in the flare ribbons/footpoints in the lower atmosphere.

Keywords: Solar oscillations, Solar ultraviolet emission, Solar flares, Solar x-ray emission
Resolving the Super-Earth/Gas Giant Connection in Stellar Mass and Metallicity. The observed correlation between inner super-Earths (SE) and outer gas giants (GG) places strong constraints on formation theories. Building on previous work, M. L. Bryan &amp; E. J. Lee showed that there is a statistically significant positive correlation between super-Earths and outer gas giants around metal-rich FGK stars, and that this correlation disappears for metal-poor hosts. Here we consider how this connection evolves across stellar mass. Starting with our sample of 85 M dwarfs (&lt;0.6 M⊙) hosting inner super-Earths, we calculate P(GG∣SE, [Fe/H] &gt; 0) = 9.4 (+10.2 ‑3.1)% and P(GG∣SE, [Fe/H] ≤ 0) &lt; 3.1%. Compared to the field gas giant frequency calculated from the L. J. Rosenthal et al. sample, we find P(GG∣[Fe/H] &gt; 0) = 10.3 (+6.9 ‑3.1)%, and P(GG∣[Fe/H] ≤ 0) &lt; 2.6% for M dwarfs. While we see a higher gas giant frequency around metal-rich M dwarfs for both samples, we find no significant correlations between super-Earths and gas giants. Combining our 85 M dwarf sample with our FGK sample from M. L. Bryan &amp; E. J. Lee, we resolve the SE/GG correlation in stellar mass (0.3–1.5 M⊙) and metallicity. We show the positive correlation emerges in metal-rich K dwarfs and strengthens with increasing stellar mass. Gas giant properties also impact the correlation—for metal-rich stars, the positive correlation is strengthened by (1) dynamically hot gas giants for all stellar masses; (2) distant gas giants only for higher mass stars; and (3) single gas giants for K dwarfs and multiple gas giants around more massive stars. We discuss how the stellar mass dependence of the inner–outer planet correlation can be understood from the increasing disk mass budget for higher mass stars.

Keywords: Exoplanets
Spectral Diversity of DiSCo's TNOs Revealed by JWST: Early Sculpting and Late Irradiation. The spectral diversity of trans-Neptunian objects (TNOs) is crucial for understanding the processes that led to the formation and evolution of planetesimals in the outer solar system. Using near-IR (NIR) spectra obtained by the James Webb Space Telescope (JWST) as part of the DiSCo-TNOs large program, we report the detection of well-clustered subgroups of TNOs. A first subgroup has strong NIR features with contributions from H2O, CO2, CO, CH3OH, and other organic molecules. The 2.27 μm band area, commonly attributed to methanol, decreases with increasing eccentricity, which is compatible with a late destruction of CH3OH by cosmic ion irradiation at the edge of the heliosphere. The absence of the strongest CH3OH bands in the JWST spectra is compatible with an irradiation-induced surface stratification, with CH3OH abundance increasing with increasing depth. A second subgroup has much weaker NIR bands, and these cannot be explained by a late irradiation scenario. This group is further divided into two subgroups (cold classical TNOs and objects with low perihelion) that are spectrally very similar except for their CO2 band area. We propose two possible interpretations. In one scenario, the TNO subgroups sampled a similar molecular inventory in the protoplanetary disk, after which early surface processes, such as primordial sublimation or irradiation from the young Sun, sculpted the two groups before planetary migration occurred. In a second scenario, the subgroups formed in different locations of the disk where molecules were available in different abundances. A combination of both scenarios is also possible.

Keywords: Kuiper belt, Classical Kuiper belt objects, Infrared spectroscopy, Ice spectroscopy, Molecular spectroscopy, Carbon dioxide, James Webb Space Telescope, Scattered disk objects, Protoplanetary disks, Detached objects, Trans-Neptunian objects, Complex organic molecules
Quasiperiodic Super-Alfvénic Slippage along Flare Ribbons Observed by the Interface Region Imaging Spectrograph. The apparent slipping motion of flare loops is regarded as a key feature of the 3D magnetic reconnection in the solar flares. The slippage with a super-Alfvénic speed could be defined as slipping–running reconnection, while the slippage with a sub-Alfvénic speed is called slipping reconnection. Due to the limitation of the observational instrument temporal resolution, the apparent slippage of the flare loop footpoints along the flare ribbons with super-Alfvénic speed is quite rare to our knowledge. In this Letter, we report a unique event that exhibits not only the sub-Alfvénic slippage but also the quasiperiodic super-Alfvénic slippage of ribbon substructures during a C3.4-class flare (SOL2023-01–18-T15:23), using the high-temporal-resolution observations of the Interface Region Imaging Spectrograph (∼2 s). The super-Alfvénic slippage with a speed of up to ∼1688 km s‑1 is directly observed in this study. The calculated period of the apparent super-Alfvénic slippage in both ribbons is between 8.4 and 11.9 s. This work provides the first observational evidence of the periodicity for the slipping–running magnetic reconnection.

Keywords: Solar oscillations, Solar flares, Solar magnetic reconnection, Solar extreme ultraviolet emission
Subclustering and Star Formation Efficiency in Three Protoclusters in the Central Molecular Zone. We present the highest-resolution (∼0 04) Atacama Large Millimeter/submillimeter Array 1.3 mm continuum observations so far of three massive star-forming clumps in the Central Molecular Zone (CMZ), namely 20 km s‑1 C1, 20 km s‑1 C4, and Sgr C C4, which reveal prevalent compact millimeter emission. We extract the compact emission with astrodendro and identify a total of 199 fragments with a typical size of ∼370 au, which represent the first sample of candidates of protostellar envelopes and disks and kernels of prestellar cores in these clumps that are likely forming star clusters. Compared with the protoclusters in the Galactic disk, the three protoclusters display a higher level of hierarchical clustering, likely a result of the stronger turbulence in the CMZ clumps. Compared with the mini-starbursts in the CMZ, Sgr B2 M and N, the three protoclusters also show stronger subclustering in conjunction with a lack of massive fragments. The efficiency of high-mass star formation of the three protoclusters is on average 1 order of magnitude lower than that of Sgr B2 M and N, despite a similar overall efficiency of converting gas into stars. The lower efficiency of high-mass star formation in the three protoclusters is likely attributed to hierarchical cluster formation.

Keywords: Protostars, Galactic center, Star formation