Sazuna/UAT_keywords huggingface dataset:
Large-scale Wind-driven Structures in the Orion Nebula. A study of [C II] 158 μm and H I 21 cm spectroscopic images plus high-velocity-resolution optical and ultraviolet spectra has shown the structure of the Orion Nebula to be different from that found from the study of those data separately. The [C II] features recently identified as the [C II] shell are shown to be part of the Veil-B H I foreground layer. Jointly called the outer shell, it covers the bright Huygens Region and the Extended Orion Nebula. Its maximum expansion velocity is 15 km s‑1. Closer to θ1 Ori C there is a second expanding shell, called the inner shell. It has an expansion velocity of 27 km s‑1, and probably results from a more recent period of strong wind from one or more of the Trapezium stars. Even closer to θ1 Ori C there is a central high-ionization bubble, freely expanding toward the observer but slowed in the opposite direction by photoionized gas coming off the main ionization front. Utilization of spectroscopic measures of the equivalent width of Hβ shows that the enhanced emission in [C II] seen just outside the visual wavelength boundaries of the Orion Nebula is not caused by limb-brightening of the outer shell. This enhanced emission is due to the radiation field of the Trapezium stars being filtered by intervening residual neutral hydrogen. A velocity component near 30 km s‑1 (heliocentric) first seen in H I is also present in [C II], and may result from a foreground cloud of the ISM.

Keywords: Gaseous nebulae
Calibrating the Instrumental Drift in MAROON-X Using an Ensemble Analysis. MAROON-X is a state-of-the-art extreme-precision radial velocity spectrograph deployed on the 8.1 m Gemini-N telescope on Maunakea, Hawai'i. Using a stabilized Fabry─Pérot etalon for wavelength and drift calibration, MAROON-X has achieved a short-term precision of ∼30 cm s−1. However, due to a long-term drift in the etalon (2.2 cm s−1 per day) and various interruptions of the instrument baseline over the first few years of operation, MAROON-X experiences radial velocity (RV) offsets between observing runs several times larger than the short-term precision during any individual run, which hinders the detection of longer-period signals. In this study, we analyze RV measurements of 11 targets that either exhibit small RV scatter or have signals that can be precisely constrained using Keplerian or Gaussian process models. Leveraging this ensemble, we calibrate MAROON-X's run offsets for data collected between 2020 September and early 2024 January to a precision of ∼0.5 m s−1. When applying these calibrated offsets to HD 3651, a quiet star, we obtain residual velocities with an rms of &lt;70 cm s−1 in both the red and blue channels of MAROON-X over a baseline of 29 months. We also demonstrate the sensitivity of MAROON-X data calibrated with these offsets through a series of injection-recovery tests. Based on our findings, MAROON-X is capable of detecting sub m s−1 signals out to periods of more than 1000 days.

Keywords: High resolution spectroscopy, Radial velocity
Echoes in the Noise: Posterior Samples of Faint Galaxy Surface Brightness Profiles with Score-based Likelihoods and Priors. Examining the detailed structure of galaxy populations provides valuable insights into their formation and evolution mechanisms. Significant barriers to such analysis are the nontrivial noise properties of real astronomical images and the point-spread function, which blurs structure. Here we present a framework which combines recent advances in score-based likelihood characterization and diffusion model priors to perform a Bayesian analysis of image deconvolution. The method, when applied to minimally processed Hubble Space Telescope data, recovers structures which have otherwise only become visible in next-generation James Webb Space Telescope imaging.

Keywords: Nonparametric inference, Convolutional neural networks, Deconvolution, Spiral galaxies
Probing Two-dimensional Asymmetries of an Exoplanet Atmosphere from Chromatic Transit Variation. We propose a new method for investigating atmospheric inhomogeneities in exoplanets through transmission spectroscopy. Our approach links chromatic variations in conventional transit model parameters—central transit time, total and full durations, and transit depth—to atmospheric asymmetries. By separately analyzing atmospheric asymmetries during ingress and egress, we can derive clear connections between these variations and the underlying asymmetries of the planetary limbs. Additionally, this approach enables us to investigate differences between the limbs slightly offset from the terminator on the dayside and the nightside. We applied this method to JWST's NIRSpec/G395H observations of the hot Saturn exoplanet WASP-39 b. Our analysis suggests a higher abundance of CO2 on the evening limb compared to the morning limb and indicates a greater probability of SO2 on the limb slightly offset from the terminator on the dayside relative to the nightside. These findings highlight the potential of our method to enhance the understanding of photochemical processes in exoplanetary atmospheres.

Keywords: Exoplanets, Transits, Exoplanet atmospheres, Transmission spectroscopy
Infrared Fluxes and Lightcurves of Near-Earth Objects: The Full Spitzer Sample. The IRAC camera on the Spitzer Space Telescope observed 2175 near-Earth objects (NEOs) during its Warm Mission phase, primarily in three large surveys, and also in a small number of a dedicated projects. In this paper, we present the final reprocessing of the NEO data and determine fluxes at 3.6 μm (where available) and 4.5 μm. The observing windows range from minutes to nearly 10 hours, which means that, for 39 NEOs, we observe a complete lightcurve, and for these objects, we present period and amplitude estimates and derive minimum cohesive strengths for the objects with well-determined periods. For an additional 128 objects, we detect a significant fraction of a complete lightcurve and present estimated lower limits to their rotation periods. This paper presents the final and definitive Spitzer/IRAC NEO flux catalog.

Keywords: Near-Earth objects, Asteroid rotation
Spatially Resolved Galactic H II Regions Observed by the LAMOST Medium-resolution Spectroscopic Survey of Nebulae (LAMOST MRS-N). We present spatially resolved spectroscopic observations of 10 isolated Galactic H II regions using data from the LAMOST Medium-Resolution Spectroscopic Survey of Nebulae (LAMOST MRS-N). The high spatial resolution of the data allows us to investigate the 1D radial profiles of emission-line fluxes (Hα, [S II], and [N II]), flux ratios ([N II]/Hα, [S II]/Hα, and [S II]/[N II]), and radial velocities of these three emission lines. Among these regions, two are ionization bounded, while the remaining eight are matter bounded. The matter-bounded H II regions exhibit shallower slopes in their radial flux profiles compared to the ionization-bounded ones. In most cases, the [N II]/Hα and [S II]/Hα ratios increase with distance from the center of the H II regions, consistent with model predictions that low-ionization emissions dominate the outer zones of these regions. The two ionization-bounded H II regions have kinematic ages t of 0.2 and 0.3 Myr, while the matter-bounded regions span ages from 1 to 12 Myr. For the matter-bounded H II regions, the optical emission flux decreases continuously beyond the photodissociation region (PDR), extending to approximately 1–4 times the radius of the PDR (rPDR). The escape fraction fesc of ionizing photons, derived from 1D Hα radial flux profiles, is ∼0% for ionization-bounded H II regions, while it ranges from 50% to 90% for the matter-bounded H II regions. The correlation between fesc and t suggests that evolved H II regions (with t &gt; 1 Myr) contribute more significantly to ionizing the surrounding diffuse ionized gas compared to younger, newly formed H II regions.

Keywords: Warm ionized medium, Photoionization, H II regions
Hα Variability of AB Aur b with the Hubble Space Telescope: Probing the Nature of a Protoplanet Candidate with Accretion Light Echoes. Giant planets generate accretion luminosity as they form. Much of this energy is radiated in strong Hα line emission, which has motivated direct imaging surveys at optical wavelengths to search for accreting protoplanets. However, compact disk structures can mimic accreting planets by scattering emission from the host star. This can complicate the interpretation of Hα point sources, especially if the host star itself is accreting. We describe an approach to distinguish accreting protoplanets from scattered-light disk features using "accretion light echoes." This method relies on variable Hα emission from a stochastically accreting host star to search for a delayed brightness correlation with a candidate protoplanet. We apply this method to the candidate protoplanet AB Aur b with a dedicated Hubble Space Telescope Wide Field Camera 3 program designed to sequentially sample the host star and the candidate planet in Hα while accounting for the light travel time delay and orbital geometry of the source within the protoplanetary disk. Across five epochs spanning 14 months, AB Aur b is over 20 times more variable than its host star; AB Aur's Hα emission changes by 15% while AB Aur b varies by 330%. These brightness changes are not correlated, which rules out unobstructed scattered starlight from the host star as the only source of AB Aur b's Hα emission and is consistent with tracing emission from an independently accreting protoplanet, inner disk shadowing effects, or a physically evolving compact disk structure. More broadly, accretion light echoes offer a novel tool to explore the nature of protoplanet candidates with well-timed observations of the host star prior to deep imaging in Hα.

Keywords: Exoplanet formation, Protoplanetary disks
HST SHEL: Revealing Haze and Confirming Elevated Metallicity in the Warm Neptune HAT-P-26b. We present a new and extended transmission spectrum of the warm Neptune HAT-P-26b spanning wavelengths between 0.29 and 5.0 μm. This spectrum is derived from new HST STIS G430L observations from the PanCET program, a reanalysis of the previously published HST STIS G750L data, along with the previously published HST WFC3 IR G102 and G141 data, and the two Spitzer IRAC photometric points at 3.6 and 4.5 μm. We present this analysis as part of the Sculpting Hubble's Exoplanet Legacy program, where the goals are to analyze all HST archival observations of transiting exoplanets using a uniform and homogeneous reduction technique. With the new wavelength coverage, we identify a scattering slope that is weaker than Rayleigh scattering and is best-matched by models incorporating a haze-only scenario. Our retrieval analysis reveals an atmospheric metallicity of 15  × solar which suggests that HAT-P-26b may have formed further out in the protoplanetary disk, in a region rich in hydrogen and helium but with fewer heavy elements, and later migrated inward. This supersolar metallicity places HAT-P-26b below the mass─metallicity trend of the solar system. Looking ahead, recent observations from JWST NIRISS/SOSS and NIRSpec/G495H will provide critical, high-precision data that extend the spectral coverage into the infrared to further constrain the atmospheric composition and structure of HAT-P-26b. These observations have the potential to confirm or refine the metallicity and haze scenario presented here, offering unprecedented insights into the atmospheric properties of warm Neptunes and the processes governing their formation and migration histories.

Keywords: Exoplanet atmospheres, Transits, Exoplanets, Transmission spectroscopy
An Analysis of Spitzer Phase Curves for WASP-121b and WASP-77Ab. We present analyses of Spitzer InfraRed Array Camera (IRAC) 3.6 μm and 4.5 μm phase-curve observations of hot Jupiters WASP-77Ab and WASP-121b. For WASP-121b, we find amplitudes of 1771 ± 95 ppm (3.6 μm) and 2048 ± 109 ppm (4.5 μm), and near-zero offsets of ‑0 78 ± 1 87 (3.6 μm) and 0 42 ± 1 74 (4.5 μm), consistent within 2.2σ and 1.3σ, respectively, with JWST Near Infrared Spectrograph results. For WASP-77Ab, we find amplitudes of 535 ± 52 ppm (3.6 μm) and 919 ± 40 ppm (4.5 μm), and offsets of 33 45 ± 2 79 (3.6 μm) and 16 28 ± 2 52 (4.5 μm). We report day- and nightside brightness temperatures: for WASP-121b, 2779 ± 40 K (3.6 μm) and 2905 ± 51 K (4.5 μm) (day) and 1259 ± 67 K (3.6 μm) and 1349 ± 54 K (4.5 μm) (night); for WASP-77Ab, 1876 ± 23 K (3.6 μm) and 1780 ± 25 K (day) and 1501 ± 22 K (3.6 μm) and 1234 ± 20 K (4.5 μm) (night). Comparing WASP-121b data to general circulation models, we find evidence for drag inhibiting day-to-night heat transfer, which our model reproduces using magnetic circulation. Further, comparing both planets' data to energy balance models, we show suppressed circulation in WASP-121b and potential evidence for an unusually high Bond albedo in WASP-77Ab. We add both planets to the Spitzer population study of previously identified trends in offset versus orbital period, finding that a positive trend is weakened, but not eliminated, by including these planets.

Keywords: Exoplanets, Hot Jupiters, Exoplanet atmospheric dynamics, Exoplanet detection methods, Transit photometry, Exoplanet atmospheres
KMTNet View of Blue Large-amplitude Pulsators Toward the Galactic Bulge. I. Discovery of Wide-orbit Companions in OGLE-BLAP-006. Blue large-amplitude pulsators (BLAPs), a recently classified type of variable stars, are evolved objects likely formed through interactions between stars in a binary system. However, only two BLAPs with stellar companions have been discovered to date. This paper presents photometric data from the Korea Microlensing Telescope Network (KMTNet) for three BLAPs located in the direction of the Galactic bulge: OGLE-BLAP-006, OGLE-BLAP-007, and OGLE-BLAP-009. The data were collected over eight consecutive years, beginning in 2016, with a high cadence of approximately 15 minutes. Frequency analysis of light variations revealed OGLE-BLAP-006 as a multimode pulsator with a dominant frequency of 37.88 day‑1 and two new frequencies of 38.25 and 35.05 day‑1. In contrast, OGLE-BLAP-007 and OGLE-BLAP-009 exhibit single-mode pulsation. By combining the KMTNet data with archival OGLE observations, we investigated pulsation timing variations of the BLAPs using an O ‑ C diagram to identify the light travel time effect caused by the orbital motion of their companions. We found that OGLE-BLAP-006, with no evidence of close companions, has two wide-orbit companions with orbital periods of approximately 4700 and 6300 days, making it the third known BLAP in a stellar system; however, no companions were found for OGLE-BLAP-007 and OGLE-BLAP-009. Furthermore, we identified seven other BLAP candidates with wide companions using OGLE data, suggesting that such systems are relatively common. We propose that a BLAP with a wide companion may be a merger remnant of an inner close binary within a hierarchical triple system.

Keywords: Multiple stars, Stellar pulsations, Timing variation methods, Blue large-amplitude pulsators, Stellar evolution
Occurrence Rates of Accreting Companions from a New Method for Computing Emission-line Survey Sensitivity: Application to the Hα Giant Accreting Protoplanet Survey. A key scientific goal of exoplanet surveys is to characterize the underlying population of planets in the local galaxy. In particular, the properties of accreting protoplanets can inform the rates and physical processes of planet formation. We develop a novel method to compute sensitivity to protoplanets in emission-line direct-imaging surveys, enabling estimates of protoplanet population properties under various planetary accretion and formation theories. In this work, we specialize to the case of Hα and investigate three formation models governing the planetary-mass-to-mass-accretion-rate power law and two accretion models that describe the scaling between the total accretion luminosity and observable Hα line luminosity. We apply our method to the results of the Magellan Giant Accreting Protoplanet Survey, to place the first constraints on accreting companion occurrence rates in systems with transitional circumstellar disks. We compute the posterior probability for transitional disk systems to host an accreting companion ( ) within 2″ (∼200 au). Using our two accretion models, we find consistent protoplanet rates, with median and 68% credible intervals of   and   accreting companions per star, respectively. Our technique enables studying protoplanet populations under flexible assumptions about planet formation. This formalism provides the statistical underpinning necessary for protoplanet surveys to discriminate among formation and accretion theories for planets and brown dwarfs.

Keywords: Accretion, Brown dwarfs, Astrometric exoplanet detection, H alpha photometry, Direct imaging, Exoplanet detection methods, Exoplanet formation
The S-PLUS Fornax Project (S+FP): Mapping Globular Clusters Systems within 5 Virial Radii around NGC 1399. We present the largest sample (∼13,000 candidates, ∼3000 of which are bona fide candidates) of globular cluster (GCs) candidates reported in the Fornax cluster so far. The survey is centered on the NGC 1399 galaxy, extending out to 5 virial radii (Rvir) of the cluster. We carried out a photometric study using images observed in the 12-band system of the Southern Photometric Local Universe Survey (S-PLUS), corresponding to 106 pointings, covering a sky area of ∼208 square degrees. Studying the properties of spectroscopically confirmed GCs, we have designed a method to select GC candidates using structural and photometric parameters. We found evidence of color bimodality in two broadband colors, namely (g − i)0 and (g − z)0, while, in the narrow bands, we did not find strong statistical evidence to confirm bimodality in any color. We analyzed the GCs luminosity functions (GCLF) in the 12 bands of S-PLUS, and we can highlight two points: (a) due to the relatively shallow depth of S-PLUS, it is only possible to observe the bright end of the GCLF and, (b) at that level, in all of the bands, it can be considered to be the log-normal distribution typical for GC systems. With the spatial coverage reached in this study, we are able, for the first time, to explore the large-scale distribution of GCs within and around a galaxy cluster. In particular, we noted that the GCs might be clustered along substructures, which trace the current cluster buildup.

Keywords: Globular star clusters, Galaxy clusters, Galaxy formation, Surveys, Galaxy evolution
Size Constraint on Hayabusa2 Extended Mission Rendezvous Target 1998 KY<SUB>26</SUB> via VLT/VISIR Nondetection. 1998 KY26 is a tiny near-Earth asteroid (H = 26.1) discovered in 1998. It has been selected as the target of the Hayabusa2 extended mission, which will rendezvous with 1998 KY26 in 2031. However, one of the most basic physical properties, size, remains poorly constrained, posing potential challenges for spacecraft operations. We aimed at constraining the size of 1998 KY26 by means of thermal infrared observations. We performed thermal infrared observations of 1998 KY26 using the ESO Very Large Telescope/VISIR on three consecutive nights in 2024 May. After stacking all frames, we find no apparent detection of 1998 KY26 on the resulting images. The upper-limit flux density of 1998 KY26 is derived as 2 mJy at 10.64 μm. From this upper-limit flux density obtained via non-detection, we conclude that the diameter of 1998 KY26 is smaller than 17 m with thermophysical modeling. This upper limit size is smaller than the radar derived 30 (±10) m. Our size constraint on 1998 KY26 is essential for the operation of the Hayabusa2 spacecraft during proximity operations using remote sensing instruments as well as a possible impact experiment using the remaining projectile.

Keywords: Near-Earth objects, Asteroids, Photometry
FAST Drift Scan Survey for H I Intensity Mapping. II. Stacking-based Beam Construction of the 19-feed Array at 1.4 GHz. Neutral hydrogen (H I) intensity mapping (IM) presents great promise for future cosmological large-scale structure surveys. However, a major challenge for H I IM cosmological studies is to accurately subtract the foreground contamination. An accurate beam model is crucial for improving the quality of foreground subtraction. In this work, we develop a stacking-based beam reconstruction method utilizing the radio continuum point sources within the drift-scan field. Based on the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we employ two sets of drift-scan survey data and merge the measurements to construct the beam patterns of the 19 FAST L-band feeds. To model the beams, we utilize the Zernike polynomial, which effectively captures asymmetric features of the main beam and the different side lobes. Due to the symmetric location of the beams, the main features of the beams are closely related to the distance from the center of the feed array, e.g., as the distance increases, side lobes become more pronounced. This modeling pipeline leverages the stable drift-scan data to extract beam patterns while accounting for and excluding the reflector's changing effects. It provides a more accurate measurement beam and a more precise model beam for FAST H I IM cosmology surveys.

Keywords: Large-scale structure of the universe, Surveys, Drift scan imaging, Radio astronomy, Astronomical methods
A Catalog of Distance Determinations for 5 Million Stars in LAMOST DR10. Using the distance estimation method outlined in J. L. Carlin et al., a Bayesian approach specifically tailored for LAMOST data, we estimated distances for 7,450,303 spectra from 5,394,174 unique stars in the LAMOST DR10 low-resolution data set. To accommodate the significant increase in data volume and quality in LAMOST DR10, several improvements were applied to the method in J. L. Carlin et al.: utilizing denser isochrones, increasing the density of interpolated isochrone grids, and incorporating Gaia G-band magnitudes alongside Two Micron All Sky Survey K-band magnitudes for more comprehensive distance estimates. A comparison with Gaia parallaxes shows good consistency across the data. For parallaxes below 1 mas, the estimated distances are underestimated by 4% for the K band and 10% for the G band, while for parallaxes below 0.25 mas, the distances are overestimated by 9% for the K band and 7% for the G band. Distance uncertainties initially increase with distance, with relative distance uncertainties starting at 5% at 1 kpc and rising to 17% at 20 kpc, then decreasing to 10%─15% for distances greater than 50 kpc. The number of stars with distances between 5 and 10 kpc is ∼1.8 × 105, and ∼6 × 104 for distances greater than 10 kpc.

Keywords: Surveys, Milky Way stellar halo, Stellar distance, Milky Way Galaxy