Sazuna/UAT_keywords huggingface dataset:
Architecture Classification for Extrasolar Planetary Systems. This paper presents a classification framework for the architectures of planetary systems based on a complete survey of the confirmed exoplanet population. With nearly 6000 confirmed exoplanets discovered, including more than 300 multiplanet systems with N ≥ 3 planets, the current observational sample has reached a point where it is both feasible and useful to build a classification system that divides the observed population into meaningful categories. This framework provides a criterion for splitting planetary systems into inner and outer regimes, then further dividing inner systems into dynamical classes. The resulting categories include "peas-in-a-pod systems," with uniformly small planets, and "warm-Jupiter systems," with a mix of large and small planets, as well as "closely spaced systems" and "gapped systems," with further subdivisions based on the locations of gaps and other features. These categories can classify nearly all of the confirmed N ≥ 3 systems with minimal ambiguity. We qualitatively examine the relative prevalence of each type of system, subject to observational selection effects, as well as other notable features, such as the presence of hot Jupiters. A small number of outlier systems are also discussed. Potential additional classes of systems yet to be discovered are proposed.

Keywords: Exoplanet dynamics, Exoplanet catalogs, Exoplanet systems, Exoplanets
The PHANGS-HST-Hα Survey: Warm Ionized Gas Physics at High Angular Resolution in Nearby Galaxies with the Hubble Space Telescope. The PHANGS project is assembling a comprehensive, multiwavelength data set of nearby (∼5─20 Mpc), massive star-forming galaxies to enable multiphase, multiscale investigations into the processes that drive star formation and galaxy evolution. To date, large survey programs have provided molecular gas (CO) cubes with the Atacama Large Millimeter/submillimeter Array, optical integral field unit (IFU) spectroscopy with the Very Large Telescope/Multi-Unit Spectroscopic Explorer (MUSE), high-resolution near-ultraviolet─optical imaging in five broadband filters with Hubble Space Telescope (HST), and infrared imaging in NIRCAM+MIRI filters with JWST. Here we present PHANGS-HST-Hα, which has obtained high-resolution (∼2─10 pc), narrowband imaging in the F658N or F657N filters with the HST/WFC3 camera of the warm ionized gas in the first 19 nearby galaxies observed in common by all four of the PHANGS large programs. We summarize our data reduction process, with a detailed discussion of the production of flux-calibrated, Milky Way extinction-corrected, continuum-subtracted Hα maps. PHANGS-MUSE IFU spectroscopy data are used to background-subtract the HST-Hα maps and to determine the [N II] correction factors for each galaxy. We describe our public data products (the data released as part of this work include the reduced drizzled narrowband images and the flux-calibrated, continuum-subtracted Hα maps for each galaxy; these images are available for download via MAST at https://archive.stsci.edu/hlsp/phangs.html, as well as at the Canadian Astronomy Data Centre as part of the PHANGS archive at https://www.canfar.net/storage/vault/list/phangs/RELEASES) and highlight a few key science cases enabled by the PHANGS-HST-Hα observations.

Keywords: Warm ionized medium, Spiral galaxies
Light Streak Photometry and Streaktools. The accuracy of photometric calibration has gradually become a limiting factor in various fields of astronomy, limiting the scientific output of a host of research. Calibration using artificial light sources in low Earth orbit remains largely unexplored. Here, we demonstrate that photometric calibration using light sources in low Earth orbit is a viable and competitive alternative/complement to current calibration techniques, and explore the associated ideas and basic theory. We present the publicly available Python code Streaktools as a means to simulate and perform photometric calibration using real and simulated light streaks. Using Streaktools, we perform "pill" aperture photometry on 131 simulated streaks, and Markov chain Monte Carlo based point-spread-function (PSF) model-fitting photometry on 425 simulated streaks in an attempt to recover the magnitude zeropoint of a real exposure of the Dark Energy Camera instrument on the Blanco 4 m telescope. Our results show that calibration using pill photometry is too inaccurate to be useful, but that PSF photometry is able to produce unbiased and accurate (1σ error = 3.4 mmag) estimates of the zeropoint of a real image in a realistic scenario, with a reasonable light source. This demonstrates that light-streak photometry is a promising alternative and complement to established techniques, which should be explored and tested further.

Keywords: Calibration, Artificial satellites, Astronomy software, Flux calibration
A Tentative Detection of a Point Source in the Disk Gap of HD 100546 with VLT/SPHERE-IRDIS Sparse Aperture Masking Interferometry. We reanalyze VLT/SPHERE-IRDIS K- and H-band sparse aperture masking interferometry data of the transition disk HD 100546 observed in 2018 and 2021, respectively. We fit geometrical models to the closure phases extracted from both datasets. We compare three model classes: a forward scattering disk, a forward scattering disk plus an arbitrary asymmetric disk feature, and a forward scattering disk plus an unresolved point source in the disk gap. We find that the forward scattering disk plus point-source model is the best representation of the data. We find that this point-source candidate moved from a position of sep. =   mas, P.A. =   degrees to a sep. =   mas, P.A. =   degrees between 2018 and 2021. Both of these positions are well within the ~13 au (~120 mas) disk gap, favouring the point-source interpretation. We explore the orbital parameter space that is consistent with the measured relative astrometry. We find orbits either with a similar orientation to the outer disk, with a high eccentricity e ≿ 0.65, or orbits with a large relative inclination (∼60°) to the outer disk, and any eccentricity. Despite the significance of the observed point-source signal, follow-up observations will be necessary to conclusively determine its nature. *Based on observations collected at the European Southern Observatory under ESO programmes 2100.C-5052(B), 105.2067.001.

Keywords: Brown dwarfs, Protoplanetary disks, Exoplanets, Interferometry
Quantifying the Effect of Short-timescale Stellar Activity Upon Transit Detection in M Dwarfs. M dwarf stars comprise 70%–80% of the galaxy's stars and host most of its rocky planets. They also differ from Sunlike stars in that they are "active" for billions of years or more: rotating quickly, flaring often, and emitting large amounts of UV and X-ray light. The effects of stellar activity upon both photometry and spectroscopy make their exoplanets more difficult to detect. While activity signals such as flaring and stellar rotation can be more readily modeled or removed from photometry, the contribution of unresolved stellar activity to transit sensitivity is harder to quantify. We investigate the difference in the detectability of planetary transits around a sample of M dwarfs observed by NASA's Transiting Exoplanet Survey Satellite (TESS) Mission, characterized by a common stellar radius, effective temperature, and TESS magnitude. Our sample is classified as either "active" or "inactive" based upon the presence of Hα in emission. After removing more readily identifiable signatures of activity: stellar rotation and large flares, we perform an injection-and-recovery analysis of transits for each star. We extract detection sensitivity as a function of planetary radius and orbital period for each star. Then, we produce averaged sensitivity maps for the "active" stars and the "inactive" stars, for the sake of comparison. We quantify the extent to which signal-to-noise ratio is degraded for transit detection, when comparing an active star to an inactive star of the same temperature and apparent brightness. We aim for these sensitivity maps to be useful to the exoplanet community in future M dwarf occurrence-rate studies.

Keywords: Exoplanet detection methods, Transit photometry, Stellar activity
Color─Magnitude Diagram of NGC 205 and Its RR Lyrae Variables. We present the deepest color─magnitude diagram (CMD) for NGC 205 in the F606W (≍V) and F814W (≍I) filters. Our archival Hubble Space Telescope/Advanced Camera for Surveys field is centered ∼3 8 northwest of the galaxy's center. The CMD shows the canonical features of a predominantly intermediate-to-old age stellar population. Among other features, the CMD reveals a prominent red clump as well as a blue horizontal branch. Notably absent is any significant signature of a young main sequence typically produced by a stellar population with an age less than a few Gyr. From the magnitude of the red-giant-branch tip, we derive a distance modulus of (m − M)o = 24.66 ± 0.05. When compared with α-enhanced theoretical isochrones, the color distribution of the red giant branch stars yields a peak metallicity value of [Fe/H] = −0.51 ± 0.10. Our photometry also reveals a sample of 479 RR Lyrae variable stars (443 ab-type and 36 c-type). Utilizing equations that relate the periods and amplitudes to the metallicities of these stars, we find a mean &lt;[Fe/H]&gt; = −1.45 ± 0.02 on the Zinn &amp; West scale for the purely old stellar population in NGC 205. The quoted uncertainty represents the standard error of the mean abundance value is consistent with that of the six genuine old globular clusters in NGC 205.

Keywords: RR Lyrae variable stars, Dwarf elliptical galaxies, CCD photometry
A Bayesian Approach to Inferring Accretion Signatures in Young Stellar Objects: A Case Study with VIRUS. The mass accretion rates of young stellar objects (YSOs) are key to understanding how stars form, how their circumstellar disks evolve, and even how planets form. We develop a Bayesian framework to determine the accretion rates of a sample of 15 YSOs using archival data from the VIRUS spectrograph (R ∼ 800, 3500–5500 Å) on the Hobby–Eberly Telescope. We are publicly releasing our developed tool, dubbed nuts-for-ysos, as a Python package, which can also be applied to other spectroscopic data sets (https://github.com/laurenwillett/nuts-for-ysos). The nuts-for-ysos code fits a simple accretion model to the near-UV and optical continuum of each VIRUS spectrum. Our Bayesian approach aims to identify correlations between model parameters using the No U-Turn Sampler (NUTS). Moreover, this approach self-consistently incorporates all parameter uncertainties, allowing for a thorough estimation of the probability distribution for accretion rate not accomplished in previous works. Using nuts-for-ysos, we derive accretion rates of each YSO. We then verify the reliability of our method by comparing to results separately derived from only the spectral emission lines, and to results from earlier studies of the Lupus, Chamaeleon I, and NGC 1333 regions. Finally, we discuss what qualitative trends, covariances, and degeneracies were found among model parameters. The technique developed in this paper is a useful improvement that can be applied in the future to larger samples of YSOs observed by VIRUS or other spectrographs. *Based on observations obtained with the Hobby-Eberly Telescope (HET), which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Ludwig-Maximilians-Universitaet Muenchen, and Georg-August Universitaet Goettingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly.

Keywords: Bayesian statistics, Young stellar objects, Low mass stars, Stellar accretion, Stellar accretion disks, Protostars
Candidate RR Lyrae Associated with the Ultrafaint Dwarf Galaxy Aquarius III. We report the search of RR Lyrae in the vicinity of a newly discovered ultrafaint dwarf galaxy, Aquarius III. Based on the known RR Lyrae catalogs and gri-band light curves retrieved from public archives, we identified a RR Lyrae with distance, metallicity, and proper motion consistent with Aquarius III. Therefore, this RR Lyrae is the first variable star identified to be associated with Aquarius III, despite its projected distance is more than 15 times the half-light radius of Aquarius III. On the other hand, a dedicated time-series monitoring of the central part of Aquarius III, out to a projected radius of approximately four half-light radius, revealed there is no RR Lyrae in this region. We ran a set of synthetic color–magnitude diagrams with properties similar to Aquarius III, and found a nonnegligible probability that Aquarius III could have (at least one) RR Lyrae. We have also identified a RR Lyrae candidate but most likely it is a background halo star.

Keywords: RR Lyrae variable stars, Dwarf galaxies, Distance measure
Identifying Missing Quasars from the DESI Bright Galaxy Survey. The Dark Energy Spectroscopic Instrument (DESI) cosmology survey includes a Bright Galaxy Survey (BGS), which will yield spectra for over 10 million bright galaxies (r &lt; 20.2 AB mag). The resulting sample will be valuable for both cosmological and astrophysical studies. However, the star/galaxy separation criterion implemented in the nominal BGS target selection algorithm excludes quasar host galaxies in addition to bona fide stars. While this excluded population is comparatively rare (∼3–4 per square degrees), it may hold interesting clues regarding galaxy and quasar physics. Therefore, we present a target selection strategy that was implemented to recover these missing active galactic nuclei (AGN) from the BGS sample. The design of the selection criteria was both motivated and confirmed using spectroscopy. The resulting BGS-AGN sample is uniformly distributed over the entire DESI footprint. According to DESI survey validation data, the sample comprises 93% quasi-stellar objects (QSOs), 3% narrow-line AGN or blazars with a galaxy contamination rate of 2%, and a stellar contamination rate of 2%. Peaking around redshift z = 0.5, the BGS-AGN sample is intermediary between quasars from the rest of the BGS and those from the DESI QSO sample in terms of redshifts and AGN luminosities. The stacked spectrum is nearly identical to that of the DESI QSO targets, confirming that the sample is dominated by quasars. We highlight interesting small populations reaching z &gt; 2, which are either faint quasars with nearby projected companions or very bright quasars with strong absorption features including the Lyα forest, metal absorbers, and/or broad absorption lines.

Keywords: Quasars, Blazars, Active galaxies, Seyfert galaxies, Active galactic nuclei, Spectroscopy, Redshift surveys
Beam Measurements of Full Stokes Parameters for the FAST L-band 19-beam Receiver. The Five-hundred-meter Aperture Spherical radio Telescope (FAST) has been fully operational since 2020 January 11. We present a comprehensive analysis of the beam structure for each of the 19 feed horns on FAST's L-band receiver across the Stokes I, Q, U, and V parameters. Using an on-the-fly mapping pattern, we conducted simultaneous sky mapping using all 19 beams directed toward polarization calibrators J1407+2827 and J0854+2006 from 2020 to 2022. Electromagnetic simulations were also performed to model the telescope's beam patterns in all Stokes parameters. Our findings reveal a symmetrical Gaussian pattern in the Stokes I parameter of the central beam without strong sidelobes, while the off-center beams exhibit significant asymmetrical shapes that can be fitted using a combination of log-normal and Gaussian distributions. The inner beams have higher relative beam efficiencies and smaller beam sizes compared to those of the outer beams. The sidelobes of the inner beams contribute approximately 2% of the total flux in the main lobe, increasing to 5% for outer beams, with a peak at 6.8%. In Stokes U, a distinct four-lobed cloverleaf beam squash structure is observed, with similar intensity levels in both inner and outer beams. In Stokes V, a two-lobed beam squint structure is observed in the central beam, along with a secondary eight-lobed structure. The highest squint peak in Stokes V is about 0.3% of the Stokes I in the outer beams. These results align closely with the simulations, providing valuable insights for the design of radio multibeam observations.

Keywords: Radio spectroscopy, Spectropolarimetry, Astronomical techniques, Radio telescopes, Single-dish antennas, Astronomical instrumentation, Spectroscopy, Radio observatories
LensNet: Enhancing Real-time Microlensing Event Discovery with Recurrent Neural Networks in the Korea Microlensing Telescope Network. Traditional microlensing event vetting methods require highly trained human experts, and the process is both complex and time consuming. This reliance on manual inspection often leads to inefficiencies and constrains the ability to scale for widespread exoplanet detection, ultimately hindering discovery rates. To address the limits of traditional microlensing event vetting, we have developed LensNet, a machine learning pipeline specifically designed to distinguish legitimate microlensing events from false positives caused by instrumental artifacts, such as pixel bleed trails and diffraction spikes. Our system operates in conjunction with a preliminary algorithm that detects increasing trends in flux. These flagged instances are then passed to LensNet for further classification, allowing for timely alerts and follow-up observations. Tailored for the multiobservatory setup of the Korea Microlensing Telescope Network and trained on a rich data set of manually classified events, LensNet is optimized for early detection and warning of microlensing occurrences, enabling astronomers to organize follow-up observations promptly. The internal model of the pipeline employs a multibranch Recurrent Neural Network architecture that evaluates time-series flux data with contextual information, including sky background, the full width at half-maximum of the target star, flux errors, point-spread function quality flags, and air mass for each observation. We demonstrate a classification accuracy above 87.5% and anticipate further improvements as we expand our training set and continue to refine the algorithm.

Keywords: Gravitational microlensing, Gravitational microlensing exoplanet detection, Classification, Neural networks
A Predicted Great Dimming of T Tauri: Has it Begun?. The optical star in the T Tauri triple system is the prototype of young Sun-like stars in our galaxy. This complex and dynamic system has evidence for misaligned disks and outflows, and molecular material in a circumbinary ring that obscures the southern infrared binary, T Tau South. Observations by members of the American Association of Variable Star Observers show that T Tau North, the optical star, has dimmed by up to ∼2 mag in the visual over the course of the past decade. The dimming across the B, V, R, and I bands has a color character typical of changes in interstellar medium extinction, suggesting an increase in obscuration along the line of sight to T Tau North. Material associated with the circumbinary ring around T Tau South has been predicted to occult the optical star via wide-scale orbital motion of the system. Through analysis of the geometrical configuration and motion of dust structures in the system, it seems that a great dimming of T Tau North by line-of-sight material associated with the T Tau South binary has, in fact, begun. Based on the extent and motion of the circumbinary ring material associated with the southern binary, T Tau North will likely experience dimming events for decades to come and may disappear entirely from the optical sky as the densest midplane region of the ring traverses our line of sight.

Keywords: Circumstellar disks, T Tauri stars, Classical T Tauri stars
Cosmic Bulk Flow Analysis in Modified Gravity Theories: f(R) and Perturbed f(R) Models with Neutrino Coupling. In this study, we explore the characteristics of bulk flow across various redshift ranges within the frameworks of f(R) gravity, perturbed f(R) gravity, and perturbed f(R) gravity coupled with neutrinos. Our investigation reveals profound insights into large-scale cosmic flows and their interactions with major cosmic structures, such as the Sloan Great Wall (SGW) and the King Ghidorah Supercluster (KGSc). We find that incorporating neutrinos into the perturbed f(R) gravity model results in a substantial increase in bulk flow velocities across all redshifts, with notable enhancements in the higher redshift ranges, where velocities can exceed 3000 km s‑1 in the 0.8 &lt; z &lt; 1.4 range. Moreover, the direction of the bulk flow in this model closely aligns with the dark energy dipole, especially at redshifts z &gt; 0.4, showing near-perfect congruence with cosmic superclusters. This suggests a significant interaction between neutrinos and cosmic structures, influencing cosmic acceleration. At lower redshifts, such as 0.1 &lt; z &lt; 0.2, the bulk flow aligns with the SGW, while in the 0.4 &lt; z &lt; 0.6 range it aligns with the KGSc. In the low redshift range 0.001 &lt; z &lt; 0.016, although velocities are lower, neutrinos still subtly increase the bulk flow velocity and maintain alignment with nearby cosmic structures, such as the Local Supercluster. Our results underscore the critical role of neutrinos in shaping cosmic flows and offer new insights into the interplay between dark energy, neutrinos, and modified gravity models. Future research should delve deeper into these interactions to elucidate the mechanisms influencing large-scale cosmic structures.

Keywords: Neutrino astronomy, Neutrino masses
I-band Asymptotic Giant Branch Stars. I. Exploring a New Standard Candle for the Extragalactic Distance Scale. In the I-band color─magnitude diagrams of resolved nearby galaxies, the reddest asymptotic giant branch (AGB) stars form a previously unremarked-upon, but nevertheless distinct and easily identified population of high-luminosity stars. Hereafter we refer to this population as being comprised of I-band AGB (IAGB) stars. Identifying these stars in the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC) and in NGC 4258 (for all three of which there are published geometric distances) we find that the marginalized luminosity functions are each well approximated by single-peaked Gaussians, having 1σ dispersions of ±0.22 mag, ±0.25 mag and ±0.24 mag, respectively. The zero points for the modal I-band absolute magnitudes of IAGB stars are found to be MI = −4.49 ± 0.003 mag (stat) in the LMC (4204 stars), MI = −4.67 ± 0.008 mag (stat), for the SMC sample (916 stars), and MI = −4.78 ± 0.030 mag (stat) for NGC 4258 (62 stars). A global average over these three independent calibrations of the IAGB zero-point (weighted inversely by squares of their systematic errors) gives &lt;MI&gt; = −4.65 ± 0.119 mag (stat) ± 0.025 (sys). In Paper II we will show the results of applying the IAGB Method to 92 galaxies additional galaxies resolved by Hubble Space Telescope, reaching out to distances just short of 10 Mpc. *Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Keywords: Distance indicators, Carbon stars, Late-type giant stars