Sazuna/UAT_keywords huggingface dataset:
Emission Line Profile Variations in the Early Coronal Phase of the Nova V2944 Ophiuchi. V2944 Ophiuchi was a Fe II type novae that reached moderate excitation and displayed large variations among the profiles of its emission lines. The profiles become increasingly double-peaked as the ionization level of the parent ion increases. At the extremes, H I and O I have flat-topped profiles while the coronal features [Si VII] and [Ca VIII] peak in the line wings and have centers that fall to near the continuum level. He II, N V, and [Si VI] display intermediate behavior but in the same sense that the line center depth is smallest for He II and largest for [Si VI. A possible explanation for these profile variations is that the emission line region is ring-like in structure and becomes increasingly flattened as line excitation increases.

Keywords: Novae
Discovery of a 0.58M <SUB>⊙</SUB>, 0.9 au Companion to HIP 42313 = δ Hya. In spite of them being the main progenitors of white dwarfs, the multiplicity of intermediate mass stars is relatively less explored when compared to solar-type and O-type stars. Here we report the discovery of a new companion to the nearby 2.43M ⊙ A1V star HIP 42313 = δ Hya with a K band flux ratio of 1.3% based on a VLTI/GRAVITY interferometric observation. This new 0.58M ⊙ companion at a projected separation 16.7 mas ↔ 0.90 au explains both the Hipparcos-GaiaDR2 as well as the GaiaDR2-GaiaDR3 proper motion changes of δ Hya. Together with the previously known 0.44M ⊙ companion at ρ = 2.″7 ↔ 147 au, this makes δ Hya a hierarchical triple system. *Based on observations collected at the European Southern Observatory, Chile, Program ID 110.241W.002.

Keywords: Optical interferometry, Multiple stars, A stars
Discovery of a 0.64 M <SUB>⊙</SUB> 13.4 au Companion to the roAp Star HIP 47145 = HR 3831 = IM Vel. Our knowledge about the multiplicity of intermediate mass A- and B-type stars is still incomplete, in particular for high (3+) multiplicity systems. Here we report the discovery of a new companion to the nearby roAp star HIP 47145 = HR 3831 with a K band flux ratio of 4% based on a VLTI/GRAVITY interferometric observation. This new 0.64M ⊙ companion at a projected separation 187.5 mas ↔ 13.40 au explains the Hipparcos-GaiaDR2 proper motion change of HR 3831. Together with the previously known M ≈ 1M ⊙ companion at 3″ ↔ 214 au, this makes HR 3831 a hierarchical triple and a very likely progenitor for a system similar to 40 Eridani. *Based on observations collected at the European Southern Observatory, Chile, Program ID 110.241W.002.

Keywords: Optical interferometry, Multiple stars, Ap stars
The Behavior of Bp He-weak Stars in the Far UV-Paper IV: HD 28843. The analysis of five spectra of the Bp He-weak Si star HD 28843 recorded by the SWP camera on board the International Ultraviolet Explorer reveals variations of the far-ultraviolet spectral energy distribution over a time interval of 4 yr and eight months. Variations are present shortwards of 1700 Å which can be partly attributed to variations of lines and continuum of Si II. Other lines due to C II and Si III also contribute to the opacity in this range too. The variations suggest that silicon is not distributed in a uniform manner over the surface and that the horizontal gradients of the silicon abundance are probably quite large.

Keywords: Helium-weak stars, Chemically peculiar stars
An Estimate of the Distance to AN Ser using an RR Lyrae Period-Luminosity Relationship. The relationship between the period of a Cepheid variable star and its absolute magnitude-the Period-Luminosity, or Leavitt Law-can be used with a measurement of apparent magnitude to measure the star's distance. RR Lyrae stars are evolved low-mass stars with shorter periods and lower luminosities than Cepheids, but they are particularly useful for estimating distances to the oldest stellar clusters. We observed the brightness of an RR Lyrae star over time using the robotic telescopes of Las Cumbres Observatory to determine its period and apparent magnitude in four bands. We used that information and theoretical period-luminosity relationships for RR Lyrae stars to determine the distance to AN Ser to be 876 ± 25 pc. Our measured distance is smaller than that modeled by GAIA DR3 via stellar parallax, BP/RP spectra, and G-band photometry (959 pc).

Keywords: Stellar parallax, RR Lyrae variable stars, Cepheid variable stars, Cepheid distance, Stellar distance
Stability Analysis for General Order Central Finite-difference Hyperdiffusivity with Time Integrators of Arbitrary Accuracy. Computational studies of astrophysical fluid dynamics often make use of explicit high-order artificial dissipation terms (i.e., hyperdiffusion and hyperviscosity), that behave as high-frequency filters, shortening the dissipation range while preserving numerical stability. In this contribution, I derive the Courant-Friedrichs-Lewy stability condition for general order hyperdiffusion, when discretized via central finite differences, to arbitrary order of accuracy in the Taylor expansion.

Keywords: Astronomy software
AGN Sub-populations Important for Black Hole Mass Growth: A Rule of Thumb. For building the super-massive black hole population within a Hubble time, only sub-populations with more than ${10}^{52}\,\mathrm{erg}\,{{\rm{s}}}^{-1}/\overline{L}$ objects on the sky are relevant, where $\overline{L}$ is the sample-averaged bolometric luminosity.

Keywords: Galaxy evolution, Active galactic nuclei, Black holes, Surveys
Observational Constraints on the Metagalactic Lyα Photon Scattering Rate at High Redshift. The scattering of Lyα photons from the first radiating sources in the universe plays a pivotal role in 21 cm radio detections of Cosmic Dawn and the Epoch of Reionization through the Wouthuysen-Field effect. New data from JWST show the Lyα photon scattering rate exceeds that required to decouple the intergalactic hydrogen spin temperature from that of the Cosmic Microwave Background up to z ~ 14 and render the neutral hydrogen visible.

Keywords: Cosmology, Reionization, Intergalactic medium
On the Discovery Claim of a New z &gt; 7 Quasar. Koptelova &amp; Hwang (K22) recently claimed a new quasar discovery at z = 7.46. After careful consideration of the publicly available data underlying K22's claim, we find that the observations were contaminated by a moving solar system object, likely a main-belt asteroid. In the absence of the contaminated photometry, there is no evidence for the nearby, persistent WISE source being a high-redshift object; in fact, a detection of the source in DESI Legacy Imaging Surveys z-band rules out a redshift z &gt; 7.3. We present our findings as a cautionary tale of the dangers of passing asteroids for photometric selections.

Keywords: Early universe, Asteroids, Quasars
Calibration Target Selection for the SPARCS Satellite. The Star-Planet Activity Research CubeSat (SPARCS) is an upcoming NASA mission to understand the impact of low-mass stellar radiation on exoplanets. SPARCS will obtain photometric observations of low-mass stars in two bands: 153-171 nm (Far-UV; FUV) and 258-308 nm (Near-UV; NUV). SPARCS' absolute calibration will be derived by observing White Dwarfs (WDs). WD selected as SPARCS calibrators should vary ≤7%. Here we present a study of UV variability of potential WD calibrators, based on Galaxy Evolution Explorer and HST/UVIS photometric observations. We collected data on a sample of 29 WDs from the Mikulski Archive for Space Telescopes and identified 8 potential SPARCS calibration targets in the NUV and 5 in the FUV, for a total of 10 distinct targets. Statistical analysis shows variability &lt;3% in both bands. For some stars, the intrinsic astrophysical variability is smaller than these limits.

Keywords: Calibration, DO stars, DB stars, DA stars
Parallelization of the Symplectic Massive Body Algorithm (SyMBA) N-body Code. Direct N-body simulations of a large number of particles, especially in the study of planetesimal dynamics and planet formation, have been computationally challenging even with modern machines. This work presents the combination of fully parallelized N 2/2 interactions and the incorporation of the GENGA code's close encounter pair grouping strategy to enable MIMD parallelization of the Symplectic Massive Body Algorithm (SyMBA) with OpenMP on multi-core CPUs in shared-memory environment. SyMBAp (SyMBA parallelized) preserves the symplectic nature of SyMBA and shows good scalability, with a speedup of 30.8 times with 56 cores in a simulation with 5000 fully interactive particles.

Keywords: Planetary system formation, Celestial mechanics, Computational methods, Planetary dynamics, N-body simulations, Dynamical evolution
A Speckle Search for the Outer Companion of KIC 9832227. We present Gemini-N/'Alopeke speckle observations of KIC 9832227, a system originally predicted to become a red nova. The diffraction limited observations do not find an outer companion between 11 and 678 au that could be responsible for the period changes of the system.

Keywords: Contact binary stars, Speckle interferometry
Diffusion Coefficients of <SUP>56</SUP>Fe in C-O and O-Ne White Dwarfs. The diffusion coefficients of neutron rich nuclei in crystallizing white dwarf (WD) stars are essential microphysics input for modeling the evolution of the composition profile. Recently, molecular dynamics simulations have been used to compute diffusion coefficients for realistic mixtures of C-O and O-Ne WDs with many trace nuclides that could be important sedimentary heat sources such as 22Ne, 23Na, 25Mg, and 27Mg. In this brief note, I repeat these simulations but now include 56Fe. I find that for the large charge ratios involved in these mixtures the empirical law developed in our earlier work tends to under-predict diffusion coefficients in the moderately coupled regime by 30%-40%. As this formalism is presently implemented in the stellar evolution code MESA, it is important for authors studying mixtures containing heavy nuclides like 56Fe to be aware of these systematics. However, the impact on astrophysics is expected to be small.

Keywords: Stellar interiors, Plasma physics, White dwarf stars, Computational methods, Stellar evolution
SNART: Synchrotron Self Absorption Model For Non-relativistic Transients. We present SNART (DeMarchi &amp; Finstad 2023), software for radio synchrotron self-absorption analysis, a generalized version of the model introduced in Chevalier, Chevalier &amp; Fransson. SNART ingests flux density and frequency observations, fits them jointly, and outputs system physical parameters: magnetic field B, shock radius R, post shock energy U, electron number density n  e , circumstellar density ρ CSM, and mass loss degenerate with wind velocity $\dot{M}/{v}_{\mathrm{wind}}$ . SNART is written in Python and is publicly available via GitHub. The repository hosts an in-depth derivation of the model and a detailed description of parameter definitions in the literature. SNART is a generalized treatment of synchrotron self absorption that leaves the choice of values for p (the power-law index of the electron distribution), q (shock front acceleration), θ (electron pitch angle, commonly π/2), and f (the "filling factor," often 0.5) explicit.

Keywords: High energy astrophysics, Astronomy software, Tidal disruption, Transient sources, Time domain astronomy, Interstellar synchrotron emission, Supernovae, Radio transient sources
Hidden Companions to Nearby Intermediate-mass Stars. I. Discovery of a 0.82M <SUB>⊙</SUB>, 15 au Companion to the Resolved 0.4 au Spectroscopic Binary in HIP 67199. Further discoveries and detailed studies of close binaries of intermediate-mass stars in hierarchical triple systems are needed in order to understand their formation. Here we report the discovery of a 0.82M ⊙ companion to the intermediate mass spectroscopic binary HIP 67199 at a projected separation of 150 mas ↔ 15 au based on a VLTI/GRAVITY observation. In addition, the spectroscopic binary was spatially resolved with a projected separation 1.70 mas ↔ 0.18 au and inferred masses 1.84M ⊙ + 1.72M ⊙. Further observations can determine the amplitude of eccentricity oscillations in the inner system induced by the third star. HIP 67199 is a potential progenitor for a double white dwarf hiding within the glow of a main-sequence companion. *Based on observations collected at the European Southern Observatory, Chile, Program ID 102.D-0817(C)

Keywords: Optical interferometry, Multiple stars, A stars
Compact Sources in the A401-A399 Galaxy Cluster System Observed at 90 GHz with the MUSTANG-2 Camera. We report the fluxes of 10 compact sources in 90 GHz maps of the galaxy cluster A401 and the intercluster region between A401 and A399 from 66 hr of observations with the MUSTANG-2 receiver on the Green Bank Telescope. All sources have been previously detected in other bands (IR or radio). The flux and central coordinates of each source are fitted with 2D Gaussian profiles and fluxes are compared with an aperture photometry method. Future observations over a larger area would be a unique tool to compare theoretical predictions of source counts at 90 GHz with measured data, as well as refining their spectral index and improve extrapolations to higher frequencies.

Keywords: Cosmology, Galaxy clusters, Compact radiation sources
Spatial Coincidence between Ultra-high Energy Cosmic Rays and TeV Gamma Rays in the Direction of GRB 980425/SN 1998bw. Gamma-ray bursts (GRBs) have long been suspected as possible ultra-high energy cosmic ray (UHECR) accelerators. In this brief note, I report that GRB 980425/SN 1998bw falls within the region of interest (ROI) with the highest significance in an all-sky blind search for magnetically induced effects in the arrival directions of UHECRs conducted by the Pierre Auger Collaboration with events detected up to to 2018 August 31. There is also report in the literature of delayed TeV emission in archival Fermi LAT observations from the direction of GRB 980425/SN 1998bw. The combined probability that two distinct cosmic ray acceleration signatures in two different multimessenger experiments may appear at the same spatial location by chance is estimated to be between 1.62 × 10-3 and 0.0157.

Keywords: Gamma-ray bursts, High energy astrophysics, Gamma-ray sources, Burst astrophysics, Gamma-ray astronomy, Ultra-high-energy cosmic radiation, Cosmic rays
Hidden Companions to Nearby Intermediate-mass Stars. II. Discovery of a 0.80 M <SUB>⊙</SUB>, 10.5 au Companion to the λ Boötis Star HIP 83650. HIP 83650 is a nearby intermediate mass star that shows the rare λ Boötis phenomenon of still uncertain origin. Here we report the discovery of a companion to this star with a K band flux ratio of 5.9% based on an archival VLTI/GRAVITY observation. This 0.80M ⊙ companion at a projected separation 149.8 mas ↔ 10.5au confirms that the system is rather old as there is no detected X-ray emission from it. We therefore argue that the λ Boötis character of this star is not caused by a circumstellar debris disk (for which there is also no evidence in the near-infrared interferometry) but potentially by accretion from the ablated wind of a hot Jupiter. This can be tested with AO-assisted spectroscopy of the newly discovered companion.

Keywords: A stars, Multiple stars, Optical interferometry, Chemically peculiar stars
The Behavior of Bp He-weak Stars in the Far-UV-Paper 5: HD 142301. The analysis of eigthteen spectra of the B8 He-weak Si star HD 142301 recorded by the SWP camera on board the International Ultraviolet Explorer reveals large variations of the far-ultraviolet spectral energy distribution over a time interval of 14 yr and 5 months. Variations are present shortwards of 1700 Å which can be partly attributed to variations of lines and continuum of Si II. Other lines due to C II and Si III also contribute to the opacity in this range too. The variations suggest that silicon is not distributed in a uniform manner over the surface and that the horizontal gradients of the silicon abundance are probably large.

Keywords: Helium-weak stars, Chemically peculiar stars
A Direct Connection between the Wake and the Former Host Galaxy of a Proposed Runaway Supermassive Black Hole. This Research Note presents VLT B-band imaging of a candidate runaway supermassive black hole that was recently discovered in HST/ACS F606W+F814W imaging. The ACS data show an extremely thin, linear feature at z = 0.964 that points toward a compact galaxy at the same redshift. There is a gap between the feature and the compact galaxy, which means that the proposed causal connection between the two objects is not definitive. We show here that the linear feature extends all the way to the compact galaxy in the B-band, with no gap. The B-band morphology is difficult to reconcile with models where the compact galaxy and the linear feature are independent objects, and in particular with the proposal of Sanchez Almeida et al. that the linear feature is an edge-on disk galaxy.

Keywords: Supermassive black holes
Looking for the "Blue Bump" in the Early Light Curve of SN Ia using an Open Supernovae Catalog. In this study we used archival supernova data from a publicly available database to look for a blue excess in the early light curves of SN Ia. This blue excess represents a simple proposed method to differentiate between single- and double-degenerate formation scenarios. Our search found 2 candidates out of 40 SN Ia, and including selection effects implies an upper limit of ~50% of the supernovae in the sample originated in a binary with a non-degenerate companion.

Keywords: Degenerate matter, Astronomy databases, Optical astronomy, Light curves, White dwarf stars, Type Ia supernovae
The Behavior of Bp Si Stars in the Far UV-Paper V: HD 92664. The analysis of spectra of the B8 Si-rich HD 92664 recorded by the SWP camera on board the International Ultraviolet Explorer reveals variations of the far-ultraviolet spectral energy distribution shortwards of 1700 Å over a time interval of about 2 months. In contrast, the mid-UV flux does not vary which suggests that changes of the silicon continuous and line opacity are the cause of the variations. The iron-peak elements, chromium, manganese and iron play a lesser role than silicon in these variations. Phased on previous ephemeris, the FUV minimum occurs at the rotational phase, ϕ = 0.0, which corresponds to maximum light in the V-band and minimum longitudinal magnetic field.

Keywords: Bp stars, Chemically peculiar stars
Cool Cores in Clusters of Galaxies in the Dark Energy Survey. We search for the presence of cool cores in optically selected galaxy clusters from the Dark Energy Survey (DES) and investigate their prevalence as a function of redshift and cluster richness. Clusters were selected from the redMaPPer analysis of three years of DES observations that have archival Chandra X-ray observations, giving a sample of 99 clusters with a redshift range of 0.11 &lt; z &lt; 0.87 and a richness range of 25 &lt; λ &lt; 207. Using the X-ray data, the core temperature was compared to the outer temperature to identify clusters where the core temperature is a factor of 0.7 or less than the outer temperature. We found a cool core fraction of approximately 20% with no significant trend in the cool core fraction with either redshift or richness.

Keywords: Galaxy clusters, Intracluster medium, Cooling flows
Modeling the Transmission and Emission Spectra of K2-18b: Determining the Surfaces of Exoplanets with Hydrogen Dominated Atmospheres. Exoplanets between the sizes of Earth and Neptune are abundant in the universe yet absent in our solar system. We do not know if these "sub-Neptune" planets have a surface or how deep their surfaces may be. Recent studies have shown atmospheric chemistry may reflect the surface depth of these planets. In this work, we aim to determine if future observations-at wavelengths and resolutions applicable to JWST-can determine the surface pressure of sub-Neptunes. We present model transmission and emission spectra of the canonical sub-Neptune K2-18b assuming four different surface pressures. The transmission spectra indicate the shallow surface (1 bar) is the most distinguishable from the deeper surfaces, with differences at 2, 4-5, and 10 μm. The emission spectra also show the shallow surface as most distinguishable, noticeably around 3-4 μm.

Keywords: Exoplanets, Exoplanet surfaces, Extrasolar gaseous planets, Mini Neptunes, Exoplanet atmospheres
A Comparison of Distant and Nearby Solar Twins. Properties of solar twins at kiloparsec distances from the local standard of rest are compared to solar twins within 100 pc of the Sun. They have a velocity distribution closely similar to that of the nearby twins in addition to closely matching T eff, $\mathrm{log}(g)$ and [Fe/H]. The new twins are a kpc distant from Earth, and closer to the Galactic center. Additionally, they may be significantly older than nearby twins, and thus are useful for spectroscopic comparison with solar twins, in the search for fine structure constant variation.

Keywords: Solar analogs
The Behavior of Bp He-strong Stars in the far UV-Paper I: HD 37776. The analysis of thirty-two spectra of the Bp He-strong variable star HD 37776 recorded by the SWP camera on board the International Ultraviolet Explorer reveals variations of the far-ultraviolet spectral energy distribution over a time interval of about 26 hr. Variations are present shortwards of 1450 Å which can be partly attributed to variations of lines and continuum of Si II. Other lines due to C II, Si III and Si IV also contribute to the opacity in this range too. The variations suggest that silicon and possibly carbon are not distributed in a uniform manner over the surface.

Keywords: Chemically peculiar stars
Case A or Case B? The Effective Recombination Coefficient in Gas Clouds of Arbitrary Optical Thickness. In calculations of the ionization state, one is often forced to choose between the Case A recombination coefficient α A (sum over recombinations to all hydrogen states) or the Case B recombination coefficient α B (sum over all hydrogen states except the ground state). If the cloud is optically thick to ionizing photons, α B is usually adopted on the basis of the "on-the-spot" approximation, wherein recombinations to the ground state are ignored because they produce ionizing photons absorbed nearby. In the opposite case of an optically thin cloud, one would expect the Case A recombination coefficient to better describe the effective recombination rate in the cloud. In this paper, I derive an analytical expression for the effective recombination coefficient in a gas cloud of arbitrary optical thickness which transitions from α A to α B as the optical thickness increases. The results can be readily implemented in numerical simulations and semi-analytical calculations.

Keywords: Cosmology, Photoionization, Radiative recombination, Reionization, H II regions
A Simple Code for Rotational Broadening of Broad Wavelength Range High-Dispersion Spectra. In high dispersion spectra of rotating bodies such as stars and planets, the rotation contributes significantly to, and sometimes dominates, the line broadening. We present a simple method for rotationally broadening large wavelength ranges of high-dispersion spectra. The broadening is rapid and scales linearly with the length of the spectrum array. For large wavelength ranges, the method is much faster than the popular convolution-based broadening. We provide the code implementation of this method in a publicly accessible repository.

Keywords: High resolution spectroscopy, Stellar rotation, Astronomy data modeling
The Recent Mass Loss History of the Hypergiant RW Cep. In light of recent variability seen in RW Cep, we present an analysis of the spectral energy distribution of the star and unpublished, high spatial resolution mid-Infrared imaging. We derive a current mass-loss rate of ~7 × 10-6 M ⊙ yr-1 for the star and clear evidence of a higher mass-loss rate phase ending no more than ~100 yr ago.

Keywords: Hypergiant stars