Sazuna/UAT_keywords huggingface dataset:
A Novel Technosignature Search in the Breakthrough Listen Green Bank Telescope Archive. The Breakthrough Listen program is, to date, the most extensive search for technological life beyond Earth. Over the past 9 yr, it has surveyed thousands of nearby stars and close to 100 nearby galaxies with telescopes around the world, including the Robert C. Byrd Green Bank Telescope (GBT) in West Virginia. The goal is to find evidence of technosignatures of other civilizations, such as narrowband Doppler-drifting radio signals. Despite the GBT's location in a radio-quiet zone, the primary challenge of this search continues to be the ability to pick out genuine candidates from the high quantities of human-generated radio-frequency interference (RFI). Here we present a novel search method aimed at finding these "needle-in-a-haystack"-type signals, applied to 9684 observation cadences of 3077 stars (each observed with one or more of the L-, S-, C-, and X-band receivers) from the GBT archive. We implement a low-complexity statistical process to vet out RFI and highlight signals that, upon visual inspection, are less evidently RFI than those from previous analyses. Our work returns candidate signals found previously using both traditional and machine learning algorithms, as well as many not previously identified. This analysis represents the largest data set searched for technosignatures to date, and highlights the efficacy that traditional algorithms continue to have in these types of technosignature searches. We find that less than 1% of stars host transmitters brighter than ∼0.3 Arecibo radar equivalents broadcasting in our direction over the frequency band covered.

Keywords: Search for extraterrestrial intelligence, Technosignatures, Radio astronomy
Bolide Infrasound Signal Morphology and Yield Estimates: A Case Study of Two Events Detected by a Dense Acoustic Sensor Network. Two bolides (2016 June 2 and 2019 April 4) were detected at multiple regional infrasound stations, with many of the locations receiving multiple detections. Analysis of the received signals was used to estimate the yield, location, and trajectory, as well as the type of shock that produced the received signal. The results from the infrasound analysis were compared with ground-truth information that was collected through other sensing modalities. This multimodal framework offers an expanded perspective on the processes governing bolide shock generation and propagation. The majority of signal features showed reasonable agreement between the infrasound-based interpretation and the other observational modalities, though the yield estimate from the 2019 bolide was significantly lower using the infrasound detections. There was also evidence suggesting that one of the detections was from a cylindrical shock that was initially propagating upward, which is unusual though not impossible.

Keywords: Fireballs, Meteoroids, Bolides, Meteors, Meteorites
Dynamics of Stellar Systems with Collisions: Eigenvalues and Eigenfunctions in Nearly Collisionless Limit. We examine the decay of perturbations in an infinite homogeneous self-gravitating model with a Maxwellian distribution function (DF) when weak collisions are present. In collisionless systems within the stable parameter range, the eigenvalue spectrum consists of a continuous set of real frequencies associated with van Kampen (vK) modes, which are singular eigenfunctions of the stellar DF. An initial perturbation in the stellar density and gravitational potential decays exponentially through a superposition of these modes, a phenomenon known as Landau damping. However, the perturbation in the stellar DF does not decay self similarly; it becomes increasingly oscillatory in velocity space over time, indicating the absence of eigenfunctions corresponding to the Landau damping eigenfrequencies. Consequently, we refer to perturbations undergoing Landau damping as quasi-modes rather than true eigenmodes. Even rare collisions suppress the formation of steep DF gradients in velocity space. C. S. Ng &amp; A. Bhattacharjee demonstrated that introducing collisions eliminates vK modes and transforms Landau quasi-modes into true eigenmodes forming a complete set. As the collision frequency approaches zero, their eigenfrequencies converge to those of the collisionless Landau quasi-modes. In this study, we investigate the behavior of the eigenfunction of the least-damped aperiodic mode as the collision frequency approaches zero. We derive analytic expressions for the eigenfunction in the resonance region and for the damping rate as a function of collision frequency. Additionally, we employ the standard matrix eigenvalue problem approach to numerically verify our analytical results.

Keywords: Gravitational instability, Stellar dynamics
The Super-puff WASP-193 b is on a Well-aligned Orbit. The "super-puffs" are a population of planets that have masses comparable to that of Neptune but radii similar to Jupiter, leading to extremely low bulk densities (ρp ≲ 0.2 g cm−3) that are not easily explained by standard core accretion models. Interestingly, several of these super-puffs are found in orbits significantly misaligned with their host stars' spin axes, indicating past dynamical excitation that may be connected to their low densities. Here, we present new Magellan/Planet Finder Spectrograph radial velocity measurements of WASP-193, a late F star hosting one of the least dense transiting planets known to date ( ,  , ρp = 0.060 ± 0.019 g cm−3). We refine the bulk properties of WASP-193 b and use interior structure models to determine that the planet can be explained if it consists of roughly equal amounts of metals and H/He, with a metal fraction of Z = 0.42. The planet is likely substantially reinflated due to its host star's evolution, and expected to be actively undergoing mass loss. We also measure the projected stellar obliquity using the Rossiter─McLaughlin effect, finding that WASP-193 b is on an orbit well aligned with the stellar equator, with   degrees. WASP-193 b is the first Jupiter-sized super-puff on a relatively well-aligned orbit, suggesting a diversity of formation pathways for this population of planets. *This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile

Keywords: Exoplanet astronomy, Exoplanets, Hot Jupiters
Southern Binaries with the Zorro Speckle Camera @ Gemini South. We present measurements in the context of a survey of southern hemisphere binary and multiple stellar systems observed with the Zorro Speckle dual diffraction-limited optical imaging camera on the 8.1 m Gemini South telescope carried out between 2019 and 2023. The overall motivation of our survey and some initial results of these observations are outlined to demonstrate the capabilities—and limitations—of Zorro. We report on the astrometric characterization of the instrument in terms of the precision and accuracy of our measurements and provide details of our custom-made data reduction pipeline. For targets with separations smaller than 0 4, an overall precision of 1 mas in the radial and tangential directions is obtained, while the uncertainty in position angle is 0 2. Relative astrometry and contrast brightness in the two Zorro filters at 562 and 832 nm are reported for 70 pairs on 64 distinct systems (six are triples). Eleven new binaries are found, mostly of small separations (down to 15 mas) and large brightness contrast (up to ∆m = 6 in the red channel). Our results indicate that the Zorro instrument, when properly calibrated, delivers excellent-quality data for visual binary studies of tight and/or faint companions.

Keywords: High contrast techniques, Stellar photometry, Multiple stars, Stellar masses, Fundamental parameters of stars, Solar neighborhood, Spectroscopic binary stars, Companion stars, Halo stars, Speckle interferometry, Low mass stars, Visual binary stars
Near-infrared [P II] and [Fe II] Emission-line Study of Supernova Remnants in the Magellanic Clouds. We report findings from near-infrared imaging observations of 17 young and middle-aged supernova remnants (SNRs) in the Magellanic Clouds to examine the impact of SNR shocks on dust destruction and the possible detection of supernova ejecta. We have analyzed [P II] (1.189 μm) and [Fe II] (1.257 and 1.644 μm) narrowband images obtained with the InfraRed Survey Facility 1.4 m telescope at the South African Astronomical Observatory. We calculate the P/Fe abundance ratio, X(P/Fe), using the [P II]/[Fe II] line ratio, which provides valuable information on dust content and/or processing in the interstellar medium (ISM) because P is not depleted while Fe is a refractory species. Only 6 of 17 SNRs show emission features in both [P II] and [Fe II]. Among these, N49, N63A, and N206 exhibit X(P/Fe) ratios between 1.2 and 3.0 X⊙(P/Fe), which are many times smaller than the general ISM ratio (e.g., Orion Bar ∼15 X⊙(P/Fe)), suggesting significant destruction of dust grains by the shocks. In contrast, the remnants of SN 1987A, N157B, N158A, and the clump studied in N206 have P/Fe abundance ratios that are comparable to or higher than the general ISM. For SN 1987A, the high X(P/Fe) ratio may result from the lack of Fe in the gas phase, although the flux densities fluctuate constantly due to shocks. For N157B, N158A, and the clump in N206, many interpretations are being explored, including Fe atoms bound primarily to dust grains, material from supernova ejecta, and photoionization from nearby H II regions.

Keywords: Astrophysical dust processes, Supernova remnants, Infrared astronomy, Interstellar medium, Magellanic Clouds
First Daytime Near-infrared Photometric Observations at Antarctic Dome A. Located at the highest point on the Antarctic Plateau's ice sheet, Dome A is generally believed to be one of the best places on Earth for nighttime astronomy in the optical and near-infrared (NIR) bands. Daytime optical/NIR site characteristics are yet to be quantified, however. Here we report the first daytime observations of bright stars at the J band during the austral summer of 2023/2024. The experiments were conducted using a 150 mm telescope with a field of view of 0 87 × 0 69 and a pixel size of 2 5. The sky brightness at zenith was measured to be ∼5.2 mag arcsec‑2 at noon when the solar elevation was ∼27°, and it slightly darkened to ∼5.8 mag arcsec‑2 at midnight with a solar elevation angle of ∼10°. Stars as faint as J = 10.06 mag were significantly detected at 5σ levels with an effective exposure time of 175 s around midnight. The pathfinding experiments indicate that a sensitivity ∼2 mag deeper can be reached by the planned 1 m class telescopes, taking advantage of the small free atmosphere seeing. Considering the high latitude and the extremely high fraction of clear days at this site, valuable bright transients with J ≲ 12 mag, such as (super)novae in the local universe and space debris at low orbits, within ∼1/4 of the whole sky around the south celestial pole can be timely discovered and continuously monitored throughout the year.

Keywords: Antarctic observatories, Astronomical site protection, Infrared photometry, Near infrared astronomy
First Frequency Phase Transfer from the 3 mm to the 1 mm Band on an Earth-sized Baseline. Frequency phase transfer (FPT) is a technique designed to increase coherence and sensitivity in radio interferometry by making use of the nondispersive nature of the troposphere to calibrate high-frequency data using solutions derived at a lower frequency. While the Korean very long baseline interferometry (VLBI) network has pioneered the use of simultaneous multiband systems for routine FPT up to an observing frequency of 130 GHz, this technique remains largely untested in the (sub)millimeter regime. A recent effort has been made to outfit dual-band systems at (sub)millimeter observatories participating in the Event Horizon Telescope (EHT) and to test the feasibility and performance of FPT up to the observing frequencies of the EHT. We present the results of simultaneous dual-frequency observations conducted in 2024 January on an Earth-sized baseline between the IRAM 30-m in Spain and the James Clerk Maxwell Telescope (JCMT) and Submillimeter Array (SMA) in Hawai'i. We performed simultaneous observations at 86 and 215 GHz on the bright sources J0958+6533 and OJ 287, with strong detections obtained at both frequencies. We observe a strong correlation between the interferometric phases at the two frequencies, matching the trend expected for atmospheric fluctuations and demonstrating for the first time the viability of FPT for VLBI at a wavelength of ∼1 millimeter. We show that the application of FPT systematically increases the 215 GHz coherence on all averaging timescales. In addition, the use of the colocated JCMT and SMA as a single dual-frequency station demonstrates the feasibility of paired-antenna FPT for VLBI for the first time, with implications for future array capabilities (e.g., Atacama Large Millimeter/submillimeter Array subarraying and ngVLA calibration strategies).

Keywords: Supermassive black holes, Very long baseline interferometry, Active galaxies, Calibration, Astronomical techniques, Radio interferometry
The Infrared-bright SW Knots in the Complex Ejecta of VY CMa. The red hypergiant VY CMa is remarkable for its very visible record of high-mass-loss events observed over the range of wavelengths from the optical and infrared to the submillimeter region with Atacama Large Millimeter/submillimeter Array (ALMA). The SW Clump or SW knots are unique in the ejecta of VY CMa. Except for the central star, they are the brightest sources of dusty infrared emission in its complex ejecta. In this paper we combine the proper motions from the Hubble Space Telescope images, and infrared fluxes from 2 to 12 μm with the 12CO images from ALMA to determine their ages and mass estimates. The SW knots were ejected more than 200 yr ago with an active period lasting about 30 yr, and with a total mass in the Clump &gt; 2 × 10‑2 M⊙.

Keywords: Circumstellar matter, Massive stars, Red supergiant stars, Stellar mass loss
Deep Optical Images of the Ejecta Nebula around the Wolf–Rayet Star WR 8 (HD 62910). We report the results of deep Hα and [O III] images of the bright WN6/WC4 Wolf–Rayet (WR) star WR 8 (HD 62910). These data show considerably more surrounding nebulosity than seen in prior imaging. The brighter portions of the nebula span   in diameter and exhibit considerable fine-scale structure including numerous emission clumps and bright head-tail-like features, presumably due to the effects of the WR star's stellar winds. Due to the overlap of a relatively bright band of unrelated foreground diffuse interstellar Hα emission, WR 8's nebula is best viewed via its [O III] emission. A faint   diffuse outer nebulosity is detected surrounding the nebula's main ring of emission. Comparison of the nebula's optical structure with that seen in Wide-field Infrared Survey Explorer 22 μm data shows a similarly clumpy structure but within a better-defined emission shell of thermal continuum from dust. The infrared shell is coincident with the nebula's southern [O III] emissions but is mainly seen in the fainter outer portions of the northern [O III] emission clumps. It is this greater radial distance of dust emission in the nebula's northern areas that leads to a striking off-center position of the WR star from the IR shell.

Keywords: Wolf-Rayet stars, Emission nebulae
Outflowing Gas in the Planetary Nebula K 3-54. As planetary nebulae evolve, they develop slow and strong dust-driven stellar winds, making the joint study of dust and gas essential for understanding their nature. As a pilot investigation, we selected planetary nebula (PN) K 3-54 as our target, the only known PN in the Milky Way to exhibit infrared emission from both graphene (C24) and fullerene (C60). The gas is traced via molecular line emissions from 12CO, 13CO, and C18O (J = 1 → 0), observed using the 13.7 m telescope of the Purple Mountain Observatory. We investigate the dynamics of this PN and identify a bipolar outflow. Preliminary results suggest that the large dynamical timescale of the outflow and the weak shock environment may account for the simultaneous survival of C24 and C60 within and around PN K 3-54.

Keywords: Interstellar molecules, Jets, Interstellar dynamics, Stellar mass loss, Astrochemistry, Circumstellar matter, Stellar winds, Planetary nebulae
Precise Parameters from Bayesian Spectral Energy Distribution Fitting Indicate Thermally Driven Mass Loss Likely Driver of Radius Valley. Several planet formation models have been proposed to explain the gap in the population of planets between 1.8R⊕ to 2.0R⊕ known as the "radius valley." To apply these models to confirmed exoplanets, accurate and precise host-star and planet parameters are required to ensure the observed measurements correctly match model predictions. Previous studies have emphasized the need for a larger, more precise sample to further confirm dominant formation processes. By enhancing standard spectral energy distribution fitting using Bayesian methods, we derived highly accurate and precise host-star and planet parameters. Specifically, we achieved median fractional uncertainties for stellar and planet radii of 2.4% and 3.4%, respectively. We then produced the largest, most precise sample to date of 1923 planets when compared to previous studies. This full sample, as well as a sample filtered for host stellar masses between 0.8 and 1.2M⊙, were then used to derive the slope and position of the radius valley as a function of orbital period, insolation flux, and stellar mass to compare them to predictive models and previous observational results. Our results are consistent with thermally driven mass loss with a planet radius versus orbital period slope of   for the full sample, leaning toward core-powered mass loss. The planet radius versus insolation flux slope of   for the filtered sample leaned toward photoevaporation. Also, the slope as a function of stellar mass for both samples appears more consistent with thermally driven processes when compared to models and previous studies.

Keywords: Bayesian statistics, Stellar properties, Stellar radii, Exoplanet systems, Exoplanet astronomy, Exoplanet evolution, Spectral energy distribution, Planet hosting stars, Exoplanet structure, Exoplanet formation, Stellar atmospheres
The TESS─Keck Survey. XXIV. Outer Giants May Be More Prevalent in the Presence of Inner Small Planets. We present the results of the Distant Giants Survey, a 3 yr radial velocity (RV) campaign to search for wide-separation giant planets orbiting Sun-like stars known to host an inner transiting planet. We defined a distant giant (DG) to have a = 1─10 au and   70─4000 M⊕ = 0.2─12.5 MJ, and required transiting planets to have a &lt; 1 au and Rp = 1─4 R⊕. We assembled our sample of 47 stars using a single selection function and observed each star at monthly intervals to obtain ≍30 RV observations per target. The final catalog includes a total of 12 distant companions: four giant planets detected during our survey, two previously known giant planets, and six objects of uncertain disposition identified through RV/astrometric accelerations. Statistically, half of the uncertain objects are planets and the remainder are stars/brown dwarfs. We calculated target-by-target completeness maps to account for missed planets. We found evidence for a moderate enhancement of DGs in the presence of close-in small planets (CSs), P(DG∣CS) =  %, over the field rate of P(DG) =  . No enhancement is disfavored (p ∼ 8%). In contrast to a previous study, we found no evidence that stellar metallicity raises the enhancement of P(DG∣CS) over P(DG). We found evidence that DG companions preferentially accompany shorter-period CS planets and have lower eccentricities than randomly selected giant planets. This points toward a nuanced picture of dynamically cool formation in which giants interact with, but do not disrupt, their inner systems.

Keywords: Exoplanet astronomy, Exoplanet detection methods, Bayesian statistics, Radial velocity
JWST/MIRI Study of the Enigmatic Mid-infrared Rings in the Planetary Nebula NGC 1514. While NGC 1514 is an elliptical, but complex, planetary nebula at optical wavelengths, it was discovered to have a pair of infrared-bright, axisymmetric rings contained within its faint outer shell during the course of the Wide-field Infrared Survey Explorer all-sky survey. We have obtained JWST mid-infrared imaging and spectroscopy of the nebula through the use of simultaneous observations with the MIRI Imager and Medium Resolution Spectrometer, selecting the F770W, F1280W, and F2550W filters to match each of the medium-resolution spectrometer's three grating positions. These observations show that the rings are clearly resolved and relatively distinct structures, with both filamentary and clumpy detail throughout. There is also cloud-like material that has a turbulent appearance in the interior of the rings, particularly at the longest wavelengths, and faint ejecta-like structures just outside the ring boundaries. Despite their brightness, the emission from the rings within the three imager passbands is shown to be dominated by thermal emission from very small grains, not line emission from atomic hydrogen or forbidden atomic lines, shocked molecular hydrogen, or polycyclic aromatic hydrocarbons. The Doppler velocities derived from the two brightest emission lines in the rings, however, suggest that the material from which the rings were formed was ejected during an early period of very heavy mass loss from the planetary nebula progenitor, then shaped by asymmetrical fast winds from the central binary pair.

Keywords: Circumstellar dust, Planetary nebulae, James Webb Space Telescope
Real-time Collision-free Motion Planning for Next-generation Fiber Positioners in LAMOST. Multiobject fiber-fed spectrographs have thousands of fiber positioners packed on a focal plane with shared working space to move the fiber-ends in parallel, which maximizes observation time. In order to further improve the spectrum acquiring rate, the second stage of LAMOST is pursuing miniaturization and high density of fiber positioners. However, their smaller size and increased density introduce greater challenges in positioning and replacement, which necessitate more advanced anticollision measures to ensure smooth operation. In this study, we first present a real-time control strategy that makes trajectory of positioner predictable and then propose a real-time collision-free motion-planning algorithm. We classify collisions based on predicted trajectories and obtain collision-free paths. One of the fiber positioners in each collision pair is selected as waiting robot, retracting robot or extending robot. Under real-time control, positioners will move along the collision-free paths. Simulations validated that the success rate in avoiding collisions of the proposed method increased from 98.96% to 100%. A prototype measurement platform was set up to verify the scientific validity of our algorithm, and the results have shown that all 6300 fiber positioners could avoid collisions. As the trajectory of a positioner can be divided into no more than six parts, collisions among thousands of positioners can be divided into many collision pairs. Thus, our algorithm can be used in other instruments with equal-arm theta-phi positioners.

Keywords: Sky surveys, Wide-field telescopes, Astronomical instrumentation, Spectroscopy, Algorithms