Sazuna/UAT_keywords huggingface dataset:
Time-resolved Hubble Space Telescope UV Observations of an X-Ray Quasiperiodic Eruption Source. X-ray quasiperiodic eruptions (QPEs) are a novel mode of variability in nearby galactic nuclei whose origin remains unknown. Their multiwavelength properties are poorly constrained, as studies have focused almost entirely on the X-ray band. Here, we report on time-resolved, coordinated Hubble Space Telescope far-ultraviolet (FUV) and XMM-Newton X-ray observations of the shortest period X-ray QPE source currently known, eRO-QPE2. We detect a bright UV point source (LFUV ≈ few × 1041 erg s‑1) that does not show statistically significant variability between the X-ray eruption and quiescent phases. This emission is unlikely to be powered by a young stellar population in a nuclear stellar cluster. The X-ray-to-UV spectral energy distribution can be described by a compact accretion disk ( ). Such compact disks are incompatible with typical disks in active galactic nuclei, but form naturally following the tidal disruption of a star. Our results rule out models (for eRO-QPE2) invoking (i) a classic active galactic nucleus accretion disk and (ii) no accretion disk at all. For orbiter models, the expected radius derived from the timing properties would naturally lead to disk-orbiter interactions for both quasi-spherical and eccentric trajectories. We infer a black hole mass of log10(MBH) = 5.9 ± 0.3 M⊙ and an Eddington ratio of 0.13 ; in combination with the compact outer radius, this is inconsistent with existing disk instability models. After accounting for the quiescent disk emission, we constrain the ratio of X-ray to FUV luminosity of the eruption component to be LX/LFUV &gt; 16‑85 (depending on the intrinsic extinction).

Keywords: Black holes, High energy astrophysics, Tidal disruption, X-ray transient sources, Stellar accretion disks
Pearls on a String: Dark and Bright Galaxies on a Strikingly Straight and Narrow Filament. We identify a chain of galaxies along an almost straight line in the nearby Universe with a projected length of ~5 Mpc. The galaxies are distributed within projected distances of only 7–105 kpc from the axis of the identified filament. They have redshifts in a very small range of z = 0.0361‑0.0370 so that their radial velocities are consistent with galaxy proper motions. The filament galaxies are mainly star forming and have stellar masses in a range of 109.1‑1010.7 M⊙. We search for systems with similar geometrical properties in the full-sky mock galaxy catalog of the MillenniumTNG simulations and find that, although such straight filaments are unusual and rare, they are predicted by ΛCDM simulations (4% incidence). We study the cold H I gas in a 1.3 Mpc section of the filament through H I 21 cm emission line observations and detect 11 H I sources, many more than expected from the H I mass function in a similar volume. They have H I masses 108.5‑109.5 M⊙ and are mostly within ~120 kpc projected distance from the filament axis. None of these H I sources has a confirmed optical counterpart. Their darkness together with their large H I 21 cm line widths indicates that they contain gas that might not yet be virialized. These clouds must be marking the peaks of the dark matter and H I distributions over large scales within the filament. The presence of such gas clouds around the filament spines is predicted by simulations, but this is the first time that the existence of such clouds in a filament is observationally confirmed.

Keywords: Galaxy formation, Dark matter distribution, Large-scale structure of the universe, Neutral hydrogen clouds, Cosmic web
The Bullseye: HST, Keck/KCWI, and Dragonfly Characterization of a Giant Nine-ringed Galaxy. We report the discovery and multiwavelength follow-up of LEDA 1313424 ("Bullseye"), a collisional ring galaxy (CRG) with nine readily identified rings—the most so far reported for a CRG. These data shed new light on the rapid, multiring phase of CRG evolution. Using Hubble Space Telescope (HST) imaging, we identify and measure nine ring structures, several of which are "piled up" near the center of the galaxy, while others extend to tens of kiloparsecs scales. We also identify faint patches of emission at large radii (~70 kpc) in the HST imaging and confirm the association of this emission with the galaxy via spectroscopy. Deep ground-based imaging using the Dragonfly Telephoto Array finds evidence that this patch of emission is part of an older, fading ring from the collision. We find that the locations of the detected rings are an excellent match to predictions from analytic theory if the galaxy was a 10-ring system whose outermost ring has faded away. We identify the likely impacting galaxy via Keck/KCWI spectroscopy, finding evidence for gas extending between it and the Bullseye. The overall size of this galaxy rivals that of known giant low surface brightness galaxies (GLSBs) such as Malin I, lending credence to the hypothesis that CRGs can evolve into GLSBs as their rings expand and fade. Analysis of the H I content in this galaxy from ALFALFA finds significantly elevated neutral hydrogen with respect to the galaxy's stellar mass, another feature in alignment with GLSB systems.

Keywords: Low surface brightness galaxies, Galaxy collisions, Dwarf galaxies, Emission line galaxies, Ring galaxies, Galaxy spectroscopy, Interacting galaxies, Galaxy encounters
Solar Flares Triggered by a Filament Peeling Process Revealed by High-resolution GST Hα Observations. The dynamic structures of solar filaments prior to solar flares provide important physical clues about the onset of solar eruptions. Observations of those structures under subarcsecond resolution with high cadence are rare. We present high-resolution observations covering preeruptive and eruptive phases of two C-class solar flares, C5.1 (SOL2022-11-14T17:29) and C5.1 (SOL2022-11-14T19:29), obtained by the Goode Solar Telescope at Big Bear Solar Observatory. Both flares are ejective, i.e., accompanied by coronal mass ejections (CMEs). High-resolution Hα observations reveal details of the flares and some striking features, such as a filament peeling process: individual strands of thin flux tubes are separated from the main filament, followed shortly thereafter by a flare. The estimated flux of rising strands is in the order of 1017 Mx, versus the 1019 Mx of the entire filament. Our new finding may explain why photospheric magnetic fields and overall active region and filament structures as a whole do not have obvious changes after a flare, and why some CMEs have been traced back to the solar active regions with only nonerupting filaments, as the magnetic reconnection may only involve a very small amount of flux in the active region, requiring no significant filament eruptions. We suggest internal reconnection between filament threads, instead of reconnection to external loops, as the process responsible for triggering this peeling of threads that results in the two flares and their subsequent CMEs.

Keywords: Solar chromosphere, Solar flares, Solar filament eruptions
Simultaneous Evolutionary Fits for Jupiter and Saturn Incorporating Fuzzy Cores. With the recent realization that there likely are stably stratified regions in the interiors of both Jupiter and Saturn, we construct new nonadiabatic, inhomogeneous evolutionary models with the same microphysics for each that result at the present time in respectable fits for all major bulk observables for both planets. These include the effective temperature, radius, atmospheric heavy-element and helium abundances (including helium rain), and the lower-order gravity moments J2 and J4. The models preserve from birth most of an extended "fuzzy" heavy-element core. Our predicted atmospheric helium mass fraction for Saturn is ∼0.2, close to some measured estimates but in disagreement with some published predictions. To preserve a fuzzy core from birth, the interiors of both planets must start out at lower entropies than would be used for traditional "hot start" adiabatic models, though the initial exterior mantle entropies can range from hot to warm start values. We do not see a helium ocean in Saturn's interior, and both models have inner envelopes with significant Brunt–Väisälä frequencies; this region for Saturn at the current epoch is more extended, and in it, the Brunt is larger. The total heavy-element mass fraction in Jupiter and in Saturn is determined to be ∼14% and ∼26%, respectively, though there is some play in these determinations.

Keywords: Planetary science, Planetary atmospheres, Planetary structure, Exoplanet evolution
Exclusion of a Direct Progenitor Detection for the Type Ic SN 2017ein Based on Late-time Observations. To date, SN 2017ein is the only Type Ic supernova with a directly identified progenitor candidate. This candidate points to a very massive (&gt;45 M⊙) Wolf–Rayet (WR) progenitor, but its disappearance after the explosion of SN 2017ein remains unconfirmed. In this work, we revisit SN 2017ein in late-time images acquired by the Hubble Space Telescope at 2.4–3.8 yr after peak brightness. We find this source has not disappeared, and its brightness and color remain almost the same as in the preexplosion images. Thus, we conclude that the preexplosion source is not the genuine progenitor of SN 2017ein. It is not much likelier to be a companion star of the progenitor since it has a much lower extinction than SN 2017ein; its color also seems inconsistent with a star cluster, indicated by the newly added magnitude limit in F336W, apart from F555W and F814W. We suggest, therefore, this source is an unrelated star in chance alignment with SN 2017ein. Based on the low ejecta mass, we propose that SN 2017ein is most likely originated from a moderately massive star with Mini ∼ 8–20 M⊙, stripped by binary interaction, rather than a very massive WR progenitor.

Keywords: Type Ic supernovae, Core-collapse supernovae, Massive stars, Time domain astronomy, Supernovae, Stellar evolution
TRAPPIST-1 d: Exo-Venus, Exo-Earth, or Exo-Dead?. TRAPPIST-1 d is generally assumed to be at the boundary between a Venus-like world and an Earth-like world, although recently published works on TRAPPIST-1 b and c raise concerns that TRAPPIST-1 d may be similarly devoid of a substantial atmosphere. TRAPPIST-1 d is also relatively understudied in comparison with TRAPPIST-1 e. The latter has generally appeared to be within the habitable zone of most atmospheric modeling studies. Assuming that TRAPPIST-1 d still retains a substantial atmosphere, we demonstrate via a series of 3D general circulation model experiments using a dynamic ocean that the planet could reside within the habitable zone in a narrow parameter space. At the same time, it could also be an exo-Venus- or exo-Dead-type world or in transition between between one of these. Studies like this can help distinguish between these types of worlds.

Keywords: Exoplanets
Monster Radio Jet (&gt;66 kpc) Observed in Quasar at z ∼ 5. We present the discovery of a large extended radio jet associated with the extremely radio-loud quasar J1601+3102 at z ∼ 5 from subarcsecond resolution imaging at 144 MHz with the International LOFAR Telescope. These large radio lobes have been argued to remain elusive at z &gt; 4 due to energy losses in the synchrotron emitting plasma as a result of scattering of the strong cosmic microwave background at these high redshifts. Nonetheless, the 0 3 resolution radio image of J1601+3102 reveals a northern and a southern radio lobe located at 9 and 57 kpc from the optical quasar, respectively. The measured jet size of 66 kpc makes J1601+3102 the largest extended radio jet at z &gt; 4 to date. However, it is expected to have an even larger physical size in reality due to projection effects brought about by the viewing angle. Furthermore, we observe the rest-frame UV spectrum of J1601+3102 with Gemini/GNIRS to examine its black hole properties, which results in a mass of 4.5 × 108 M⊙ with an Eddington luminosity ratio of 0.45. The black hole mass is relatively low compared to the known high-z quasar population, which suggests that a high black hole mass is not strictly necessary to generate a powerful jet. This discovery of the first ∼100 kpc radio jet at z &gt; 4 shows that these objects exist despite energy losses from inverse Compton scattering and can put invaluable constraints on the formation of the first radio-loud sources in the early Universe.

Keywords: Radio loud quasars, High-redshift galaxies, Radio jets
Discovery of the Richest Pulsating Ultramassive White Dwarf. The discovery of pulsations in ultramassive (UM) white dwarfs (WDs) can help to probe their interiors and unveil their core composition and crystallized mass fraction through asteroseismic techniques. To date, the richest pulsating UM WD known is BPM 37093 with 8 modes detected, for which detailed asteroseismic analysis has been performed in the past. In this work, we report the discovery of 19 pulsation modes in the UM WD star WD J0135+5722, making it the richest pulsating hydrogen-atmosphere UM WD known to date. This object exhibits multiperiodic luminosity variations with periods ranging from 137 to 1345 s, typical of pulsating WDs in the ZZ Ceti instability strip, which is centered at Teff ∼ 12,000 K. We estimate the stellar mass of WD J0135+5722 by different methods, resulting in M⋆ ∼ 1.12–1.14 M⊙ if the star's core is made of oxygen and neon or M⋆ ∼ 1.14–1.15 M⊙ if the star hosts a carbon oxygen core. Future analysis of the star periods could shed light on the core chemical composition through asteroseismology.

Keywords: Stellar oscillations, White dwarf stars, ZZ Ceti stars
Enough Sulfur and Iron for Potential Life Make Enceladus's Ocean Fully Habitable. The Cassini spacecraft revealed life-forming elements like CHNOP and diverse organic compounds from Enceladus's ocean. However, the availability of minor but bio-essential nutrients such as iron and sulfur remains unknown. Here, we perform geochemical modeling to explore their chemistry in Enceladus's ocean. We find that dissolved iron predominantly occurs as Fe(II) with a solubility ranging from 10‑8 to 10‑5 mole (kg H2O)‑1 (decreasing with increasing pH). Dissolved sulfur, mainly present as HS‑, is predicted to have a concentration of 10‑6 to 10‑4 mole (kg H2O)‑1, and pH has only a minor effect on S solubility. Our predicted availabilities of Fe and S are close to measured concentrations in inhabited terrestrial serpentinization fluids, implying sufficient nutrients to support potential life. Our results also suggest that the reduction of ferric iron or sulfate might supply enough energy for chemotrophic metabolisms based on these reactions to complement previously proposed methanogenesis. The levels of bioproductivity supported by S availability are overall lower than those sustained by other nutrients, but still orders of magnitude higher than the maximum level of bioproductivity estimated from the supply of chemical energy.

Keywords: Enceladus, Astrobiology, Saturnian satellites
Three Worlds in One: Venus as a Natural Laboratory for the Effect of Rotation Period on Atmospheric Circulation. Because of its rotation period of 243 days, Venus is considered a slowly rotating planet. However, its persistent superrotating atmospheric jets, which increase in speed from surface to cloud tops, effectively set a faster rotation speed than the surface rotation. Using the Venus Planetary Climate Model and wind measurements taken by the Pioneer Venus entry probes, we show that the Rossby radius of deformation of the atmosphere varies with height. The atmosphere falls into three circulation regimes: (1) from the surface to 20 km, the Rossby radius of deformation exceeds the planetary radius and no Rossby waves form; (2) from 20 to 50 km, the tropical Rossby radius becomes smaller than the planetary radius, and a circulation regime characterized by a superrotating equatorial jet and mid-latitude Rossby gyres appears; (3) from 50 to 70 km, the extratropical Rossby radius becomes smaller than the planetary radius, the jet develops mid-latitude maxima, and the Rossby gyres shift to high latitudes. Studies of exoplanetary circulation regimes as a function of rotation period have repeatedly shown a similar progression. While observing the circulations of exoplanets to confirm these predictions is not currently possible, the presence of different circulation regimes on Venus and their dependence on altitude could be tested by observing campaigns. Such evidence would be the first observational support for the theory connecting differences in planetary rotation periods to circulation regime transitions and would ground predictions of exoplanet circulations in a validated framework.

Keywords: Atmospheric dynamics, Venus, Planetary atmospheres, Exoplanet atmospheres
Looking at Infrared Background Radiation Anisotropies with Spitzer: Large-scale Anisotropies and Their Implications. We use Spitzer/IRAC deep-exposure data covering two significantly larger than before sky areas to construct maps suitable for evaluating source-subtracted fluctuations in the cosmic infrared background (CIB). The maps are constructed using the self-calibration methodology eliminating artifacts to sufficient accuracy, and subset maps are selected in each area containing approximately uniform exposures. These maps are clipped and removed of known sources and then Fourier transformed to probe the CIB anisotropies to new larger scales. The power spectrum of the resultant CIB anisotropies is measured from the data to &gt;1°, revealing the component well above that from remaining known galaxies on scales  &gt;1' . The fluctuations are demonstrated to be free of Galactic and solar system foreground contributions out to the largest scales measured. We discuss the proposed theories for the origin of the excess CIB anisotropies in light of the new data. Out of these, the model where the CIB fluctuation excess originates from the granulation power due to LIGO-observed primordial black holes as dark matter appears most successful in accounting for all observations related to the measured CIB power amplitude and spatial structure, including the measured coherence between the CIB and unresolved cosmic X-ray background (CXB). Finally we point out the use of the data to probe the CIB-CXB cross power to new scales and higher accuracy. We also discuss the synergy of these data with future CIB programs at shorter near-IR wavelengths with deep wide surveys and subarcsecond angular resolution as provided by Euclid and Roman space missions.

Keywords: Observational cosmology, Cosmic background radiation, Infrared sources, Near infrared astronomy
Laboratory Rotational Spectroscopy Leads to the First Interstellar Detection of Singly Deuterated Methyl Mercaptan (CH<SUB>2</SUB>DSH). We report an extensive rotational spectroscopic analysis of singly deuterated methyl mercaptan (CH2DSH) using both millimeter and far-infrared synchrotron spectra to achieve a global torsional analysis of the three lowest torsional substates (e0, e1, and o1) of this nonrigid species. A fit including 3419 millimeter-wave transitions along with 43 infrared torsional subband centers was performed with rms deviations of 0.233 MHz and 0.270 cm‑1, respectively, resulting in 68 fit parameters. A spectroscopic catalog built from this analysis for a temperature of 125 K has led to the first interstellar detection of CH2DSH toward the solar-like protostar IRAS 16293-2422 B. We report the identification of 46 transitions, including eight relatively unblended lines, resulting in a derived column density of (3.0 ± 0.3) × 1014 cm‑2. The column density ratio for HDCS/CH2DSH compared to HDCO/CH2DOH suggests a difference in the interstellar chemistry between the sulfur and oxygen complex organics, in particular a different link between H2CO and CH3OH and between H2CS and CH3SH. This is the first interstellar detection of a deuterated sulfur-bearing complex organic molecule and therefore an important step toward understanding the chemical origin of sulfur-based prebiotics.

Keywords: Interstellar molecules, Laboratory astrophysics, Molecular spectroscopy, Interstellar abundances, Astrochemistry
Investigating the Electron-capture Supernova Candidate AT 2019abn with JWST Spectroscopy. The James Webb Space Telescope (JWST) has opened up a new window to study highly reddened explosive transients. We present results from late-time JWST follow-up spectroscopic observations with NIRSpec and MIRI-LRS of the intermediate-luminosity red transient (ILRT) AT 2019abn. ILRTs represent a mysterious class of transients that exhibit peak luminosities between those of classical novae and supernovae and that are known to be highly dust obscured. Similar to the prototypical examples of this class of objects, NGC 300 2008-OT and SN 2008S, AT 2019abn has an extremely red and dusty progenitor detected only in pre-explosion Spitzer/IRAC imaging at 3.6 and 4.5 μm and not in deep optical or near-infrared Hubble Space Telescope images. We find that late-time observations of AT 2019abn from NEOWISE and JWST are consistent with the late-time evolution of SN 2008S. In part because they are so obscured by dust, it is unknown what produces an ILRT, with hypotheses including high-mass stellar merger events, nonterminal stellar outbursts, and terminal supernova explosions through electron capture in super-AGB (SAGB) stars. Our JWST observations show strong mid-IR class C polycyclic aromatic hydrocarbon features at 6.3 and 8.25 μm typical of carbon-rich post-AGB sources. These features suggest that the dust around AT 2019abn is composed of carbonaceous grains, which are not typically observed around red supergiants. However, depending on the strength and temperature of hot bottom burning, SAGB stars may be expected to exhibit a carbon-rich chemistry. Thus, our JWST observations are consistent with AT 2019abn having an SAGB progenitor and exploding as an electron-capture supernova.

Keywords: Infrared spectroscopy, Stellar mergers, Transient sources, Asymptotic giant branch stars, Supernovae, Infrared photometry
A Study on the Line of Sight to Galaxies Detected at Gamma-Ray Energies. The large-scale universal structure comprises strands of dark matter and galaxies with large underdense volumes known as voids. We measure the fraction of the line of sight that intersects voids for active galactic nuclei (AGN) detected by Fermi Large Area Telescope (LAT) and quasars from the Sloan Digital Sky Survey (SDSS). This "voidiness" fraction is a rudimentary proxy for the density along the line of sight to the galaxies. The voidiness of SDSS-observed quasars (QSOs) is distinctly different from randomly distributed source populations, with a median p-value of 4.6 × 10‑5 and ≪1 × 10‑7, when compared with 500 simulated populations with randomly simulated locations but matching redshifts in the 0.1 ≤ z &lt; 0.4 and 0.4 ≤ z &lt; 0.7 intervals, respectively. A similar comparison of the voidiness for LAT-detected AGN shows median p-values greater than 0.05 in each redshift interval. When comparing the SDSS QSO population to the LAT-detected AGN, we mitigate potential bias from a relationship between redshift and voidiness by comparing the LAT-detected AGN to a "redshift-matched" set of SDSS QSOs. The LAT-detected AGN between a redshift of 0.4 and 0.7 show higher voidiness compared to the redshift-matched SDSS QSO populations, with a median p-value of 2.3 × 10‑5 (a 4.1σ deviation). No deviation is found when comparing the same populations between redshifts of 0.1 and 0.4 (p &gt; 0.05). We do not study possible causes of this voidiness difference. It might relate to propagation effects from lower magnetic or radiative background fields within voids or to an environment more favorable for gamma-ray production for AGN near voids.

Keywords: Gamma-ray sources, Blazars, Voids, Gamma-ray astronomy, Gamma-rays