Sazuna/UAT_keywords huggingface dataset:
Markarian Multiwavelength Data Center (MMDC): A Tool for Retrieving and Modeling Multitemporal, Multiwavelength, and Multimessenger Data from Blazar Observations. The Markarian Multiwavelength Data Center (MMDC) is a web-based tool designed for accessing and retrieving multiwavelength and multimessenger data from blazar observations. MMDC facilitates the construction and interactive visualization of time-resolved multiband spectral energy distributions of blazars by integrating (i) archival data from over 80 catalogs and databases, (ii) optical data from all-sky survey facilities such as the All-Sky Automated Survey for Supernovae, Zwicky Transient Facility, and Panoramic Survey Telescope and Rapid Response System, and (iii) newly analyzed data sets in the optical/UV band from Swift-UVOT, in the X-ray band from Swift-X-Ray Telescope and NuSTAR observations, and the high-energy γ-ray band from Fermi-Large Area Telescope observations. MMDC distinguishes itself from other online platforms by the large quantity of available data. For instance, it includes data from all blazar observations by Swift and NuSTAR, as well as the results of detailed spectral analysis in the γ-ray band during different emission states, covering the period from 2008 to 2023. Another important distinguishing feature of MMDC is its ability to enable precise, self-consistent theoretical modeling of the observed data using machine learning algorithms trained on leptonic and lepto-hadronic models, which consider the injection of particles and all relevant cooling processes. MMDC is an innovative tool that significantly enhances blazar research by providing a comprehensive framework for data accessibility, analysis, and theoretical interpretation, thereby advancing our understanding of blazar emissions and the underlying astrophysical processes.

Keywords: Astronomy data modeling, Astronomy databases, Astronomy software, Blazars, Astronomy data analysis
Spectroscopic and Photometric Confirmation of 3 Globular and 14 Intermediate-age Clusters in the Irr II Galaxy NGC 3077. We present the results from spectroscopic and photometric analysis of 17 globular cluster (GC) candidates in the Irr II galaxy NGC 3077. The GC candidates were selected on the Hubble Space Telescope images and were cleaned of foreground Galatic stars using the GAIA parameters. We carried out aperture photometry using the multiband archival images from the Sloan Digital Sky Survey, Two Micron All Sky Survey of all candidates, and low resolution (R = 1000) spectroscopic observations of 12 GC candidates and three suspected foreground stars using the Optical System for Imaging and Low-Intermediate-Resolution Integrated Spectroscopy/Multi-Object Spectra mode at the Gran Telescopio Canarias. Age, metallicity, and extinction values were determined using both spectroscopic and photometric data, independently. We find three of the 17 candidates are old (age &gt; 10 Gyr), metal-poor ([Fe/H] &lt; ‑1.0 dex), and massive (mass &gt; 105 M ⊙) GCs with characteristics similar to the classical GCs in the Milky Way. The rest are intermediate-age clusters (IACs) with typical ages of 3–4 Gyr and in general metal-rich clusters. The radial velocities of both populations are within 100 km s‑1 of the recessional velocity of the host galaxy. A relatively large population of IACs and low value of GC specific frequency (S N = 0.7) suggest that the preinteraction galaxy was actively forming stars and star clusters, and is unlikely to be a dwarf elliptical as suggested in some previous works.

Keywords: Globular star clusters, Amorphous irregular galaxies, Star clusters
Single Transit Detection in Kepler with Machine Learning and Onboard Spacecraft Diagnostics. Exoplanet discovery at long orbital periods requires reliably detecting individual transits without additional information about the system. Common techniques, like phase folding of light curves and periodogram analysis of radial velocity data, are more sensitive to planets with shorter orbital periods, leaving a dearth of planet discoveries at long periods. We present a novel technique using an ensemble of convolutional neural networks incorporating the onboard spacecraft diagnostics of Kepler to classify transits within a light curve. We create a pipeline to recover the location of individual transits, and the period of the orbiting planet, which possesses an accuracy of &gt;80% in the long orbital period regime (50 ≤ P ≤ 800 days). Our neural network pipeline has the potential to discover additional planets in the Kepler data set, and crucially, within the η-Earth regime. We report our first candidate from this pipeline, KOI-1271.02. KOI-1271.01 is known to exhibit strong transit timing variations (TTVs), and so we jointly model the TTVs and transits of both transiting planets to constrain the orbital configuration and planetary parameters and conclude with a series of potential parameters for KOI-1271.02, as there are not enough data currently to uniquely constrain the system. We conclude that KOI-1271.02 has a radius of 5.32 ± 0.20 R ⊕ and most likely a mass of   M ⊕. Future constraints on the nature of KOI-1271.02 require measuring additional TTVs of KOI-1271.01 or observing a second transit of KOI-1271.02.

Keywords: Detection, Exoplanet detection methods, Convolutional neural networks
The Detectability of CH<SUB>4</SUB>/CO<SUB>2</SUB>/CO and N<SUB>2</SUB>O Biosignatures Through Reflection Spectroscopy of Terrestrial Exoplanets. The chemical makeup of Earth's atmosphere during the Archean (4–2.5 Ga) and Proterozoic eon (2.5–0.5 Ga) contrast considerably with the present-day: the Archean was rich in carbon dioxide and methane, and the Proterozoic had potentially higher amounts of nitrous oxide. CO2 and CH4 in an Archean Earth analog may be a compelling biosignature because their coexistence implies methane replenishment at rates unlikely to be abiotic. However, CH4 can also be produced through geological processes, and setting constraints on volcanic molecules such as CO may help address this ambiguity. N2O in a Proterozoic Earth analog may be evidence of life because N2O production on Earth is mostly biological. Motivated by these ideas, we use the code   to generate forward models and simulate spectral retrievals of an Archean and Proterozoic Earth-like planet to determine the detectability of CH4, CO2, CO, and N2O in their reflected light spectrum for wavelength range 0.25–1.8 μm. We show that it is challenging to detect CO in an Archean atmosphere for volume mixing ratio (VMR) ≤ 10%, but CH4 is readily detectable for both the full wavelength span and truncated ranges cut at 1.7 μm and 1.6 μm, although for the latter two cases the dominant gas of the atmosphere is misidentified. Meanwhile, N2O in a Proterozoic atmosphere is detectable for VMR = 10‑3 and long wavelength cutoff ≥1.4 μm, but undetectable for VMR ≤ 10‑4 . The results presented here will be useful for the strategic design of the future Habitable Worlds Observatory and the components needed to potentially distinguish between inhabited and lifeless planets.

Keywords: Extrasolar rocky planets, Bayesian statistics, Posterior distribution, Spectroscopy, Biosignatures, Exoplanet atmospheres
The Roasting Marshmallows Program with IGRINS on Gemini South. II. WASP-121 b has Superstellar C/O and Refractory-to-volatile Ratios. A primary goal of exoplanet science is to measure the atmospheric composition of gas giants in order to infer their formation and migration histories. Common diagnostics for planet formation are the atmospheric metallicity ([M/H]) and the carbon-to-oxygen (C/O) ratio as measured through transit or emission spectroscopy. The C/O ratio in particular can be used to approximately place a planet's initial formation radius from the stellar host, but a given C/O ratio may not be unique to formation location. This degeneracy can be broken by combining measurements of both the C/O ratio and the atmospheric refractory-to-volatile ratio. We report the measurement of both quantities for the atmosphere of the canonical ultrahot Jupiter WASP-121 b using the high-resolution (R = 45,000) IGRINS instrument on Gemini South. Probing the planet's direct thermal emission in both pre- and post-secondary eclipse orbital phases, we infer that WASP-121 b has a significantly superstellar C/O ratio of   and a moderately superstellar refractory-to-volatile ratio at   stellar. This combination is most consistent with formation between the soot line and H2O snow line, but we cannot rule out formation between the H2O and CO snow lines or beyond the CO snow line. We also measure velocity offsets between H2O, CO, and OH, potentially an effect of chemical inhomogeneity on the planet dayside. This study highlights the ability to measure both C/O and refractory-to-volatile ratios via high-resolution spectroscopy in the near-IR H and K bands.

Keywords: Atmospheric composition, Exoplanet formation, High resolution spectroscopy, Exoplanet atmospheres
A Fourth Planet in the Kepler-51 System Revealed by Transit Timing Variations. Kepler-51 is a ≲1 Gyr old Sun-like star hosting three transiting planets with radii ≈6–9 R ⊕ and orbital periods ≈45–130 days. Transit timing variations (TTVs) measured with past Kepler and Hubble Space Telescope (HST) observations have been successfully modeled by considering gravitational interactions between the three transiting planets, yielding low masses and low mean densities (≲0.1 g cm‑3) for all three planets. However, the transit time of the outermost transiting planet Kepler-51d recently measured by the James Webb Space Telescope 10 yr after the Kepler observations is significantly discrepant from the prediction made by the three-planet TTV model, which we confirmed with ground-based and follow-up HST observations. We show that the departure from the three-planet model is explained by including a fourth outer planet, Kepler-51e, in the TTV model. A wide range of masses (≲M Jup) and orbital periods (≲10 yr) are possible for Kepler-51e. Nevertheless, all the coplanar solutions found from our brute-force search imply masses ≲10 M ⊕ for the inner transiting planets. Thus, their densities remain low, though with larger uncertainties than previously estimated. Unlike other possible solutions, the one in which Kepler-51e is around the 2:1 mean motion resonance with Kepler-51d implies low orbital eccentricities (≲0.05) and comparable masses (∼5 M ⊕) for all four planets, as is seen in other compact multiplanet systems. This work demonstrates the importance of long-term follow-up of TTV systems for probing longer-period planets in a system.

Keywords: Transits, Hubble Space Telescope, Exoplanet astronomy, James Webb Space Telescope, Transit timing variation method, Transit photometry
A Testbed for Tidal Migration: The 3D Architecture of an Eccentric Hot Jupiter HD 118203 b Accompanied by a Possibly Aligned Outer Giant Planet. Characterizing outer companions to hot Jupiters plays a crucial role in deciphering their origins. We present the discovery of a long-period giant planet, HD 118203 c ( ,   au) exterior to a close-in eccentric hot Jupiter HD 118203 b (P  b  = 6.135 days, m  b  = 2.14 ± 0.12 M J, r  b  = 1.14 ± 0.029 R J, e  b  = 0.31 ± 0.007) based on 20 yr radial velocities (RVs). Using Rossiter–McLaughlin (RM) observations from the Keck Planet Finder, we measured a low sky-projected spin–orbit angle   for HD 118203 b and detected stellar oscillations in the host star, confirming its evolved status. Combining the RM observation with the stellar inclination measurement, we constrained the true spin–orbit angle of HD 118203 b as Ψ b  &lt; 33.°5 (2σ), indicating the orbit normal of the hot Jupiter nearly aligned with the stellar spin axis. Furthermore, by combining RVs and Hipparcos-Gaia astrometric acceleration, we constrained the line-of-sight mutual inclination between the hot Jupiter and the outer planet to be   at the 2σ level. HD 118203 is one of first hot Jupiter systems where both the true spin–orbit angle of the hot Jupiter and the mutual inclination between inner and outer planets have been determined. Our results are consistent with a system-wide alignment, with low mutual inclinations between the outer giant planet, the inner hot Jupiter, and the host star. This alignment, along with the moderate eccentricity of HD 118203 c, implies that the system may have undergone coplanar high-eccentricity tidal migration. Under this framework, our dynamical analysis suggests an initial semimajor axis of 0.3–3.2 au for the proto–hot Jupiter.

Keywords: Exoplanet dynamics, Exoplanet migration, Hot Jupiters, Astrometry, Radial velocity, Gaia
A Global Perspective with Updated Constraints on the Ultra-hot Jupiter WASP-19b: Atmospheric Properties and Stellar Activity. We present a detailed reanalysis of the atmospheric properties of WASP-19b, an ultra-hot Jupiter (1.14 M Jup, 1.41 R Jup) orbiting an active Sun-like star every 0.79 day. We reanalyze a transit and secondary eclipse of WASP-19b observed by the Hubble Space Telescope's Wide Field Camera 3 spectrograph (1.1–1.7 μm). When combined with Spitzer photometry at longer wavelengths, our analyses indicate the presence of water absorption features in both the planet's transmission and emission spectra, consistent with results from previously published studies. We jointly fit WASP-19b's dayside emission and transmission spectra with a retrieval model in order to constrain its atmospheric composition, and explore the effect of stellar activity on its transmission spectrum in greater depth. We also compare our dayside emission spectrum to predictions from a general circulation model, and conclude that magnetic drag appears to be relatively unimportant in shaping WASP-19b's atmospheric circulation. Lastly, we compare the size of WASP-19b's dayside water absorption feature to the population of hot Jupiters with similar measurements, and show that it is located in the transitional irradiation regime where temperature inversions first begin to emerge. As in previous studies, we find that the current observations provide relatively weak constraints on this planet's atmospheric properties. These constraints could be significantly improved by the addition of spectroscopically resolved observations at longer wavelengths with JWST/NIRSpec PRISM.

Keywords: Exoplanet atmospheric composition , Hubble Space Telescope, Light curves, Transmission spectroscopy, Exoplanet atmospheres
The Featherweight Giant: Unraveling the Atmosphere of a 17 Myr Planet with JWST. The characterization of young planets (&lt;300 Myr) is pivotal for understanding planet formation and evolution. We present the 3–5 μm transmission spectrum of the 17 Myr, Jupiter-size (R ∼10R ⊕) planet, HIP 67522b, observed with JWST NIRSpec/G395H. To check for spot contamination, we obtain a simultaneous g-band transit with the Southern Astrophysical Research Telescope. The spectrum exhibits absorption features 30%–50% deeper than the overall depth, far larger than expected from an equivalent mature planet, and suggests that HIP 67522b's mass is &lt;20 M ⊕ irrespective of cloud cover and stellar contamination. A Bayesian retrieval analysis returns a mass constraint of 13.8 ± 1.0 M ⊕. This challenges the previous classification of HIP 67522b as a hot Jupiter and instead, positions it as a precursor to the more common sub-Neptunes. With a density of &lt;0.10 g cm‑3, HIP 67522 b is one of the lowest-density planets known. We find strong absorption from H2O and CO2 (≥7σ), a modest detection of CO (3.5σ), and weak detections of H2S and SO2 (≃2σ). Comparisons with radiative-convective equilibrium models suggest supersolar atmospheric metallicities and solar-to-subsolar C/O ratios, with photochemistry further constraining the inferred atmospheric metallicity to 3 × 10 solar due to the amplitude of the SO2 feature. These results point to the formation of HIP 67522b beyond the water snowline, where its envelope was polluted by icy pebbles and planetesimals. The planet is likely experiencing substantial mass loss (0.01–0.03 M ⊕ Myr‑1), sufficient for envelope destruction within a gigayear. This highlights the dramatic evolution occurring within the first 100 Myr of its existence.

Keywords: Exoplanet atmospheric composition , Starspots, Transmission spectroscopy, Exoplanet evolution, James Webb Space Telescope
Simulating Self-lensing and Eclipsing Signals due to Detached Compact Objects in the TESS Light Curves. A fraction of Galactic stars have compact companions that could be white dwarfs (WDs), neutron stars (NSs), or stellar-mass black holes (SBHs). In a detached and edge-on binary system including a main-sequence star and a compact object (denoted by WD main-sequence (WDMS), NS main-sequence (NSMS), and SBH main-sequence (BHMS) systems), the stellar brightness can change periodically due to self-lensing or eclipsing features. The shape of a self-lensing signal is a degenerate function of stellar radius and the compact object's mass because the self-lensing peak strongly depends on the projected source radius normalized to the Einstein radius. Increasing the inclination angle i changes the self-lensing shape from a strict top-hat model to one with slowly increasing edges. We simulate stellar light curves due to these binary systems that are observed by NASA's Transiting Exoplanet Survey Satellite (TESS) telescope and evaluate the efficiencies to detect their periodic signatures using two sets of criteria: (i) signal-to-noise ratio (SNR) &gt;3 and N tran &gt; 1 (low confidence, LC), and (ii) SNR &gt;5 and N tran &gt; 2 (high confidence, HC). The HC efficiencies for detecting WDMS, NSMS, and BHMS systems with the inclination angle i &lt; 20° during different time spans are 5%–7%, 4.5%–6%, and 4%–5%, respectively. Detecting lensing-induced features is possible in only ≲3% and ≲33% of detectable WDMS and NSMS events. The detection efficiencies for closer source stars with higher priorities are higher and drop to zero for b ≳ R ⋆, where   is the impact parameter (a is the semimajor axis). We predict the numbers of WDs, NSs, and SBHs that are discovered from the TESS Candidate Target List stars are 15–18, 6–7, and &lt;1.

Keywords: Space telescopes, Compact binary stars, Gravitational lensing, Transient detection, Compact objects, Eclipsing binary stars, Stellar remnants, Astronomical simulations
A Centiparsec-scale Compact Radio Core in the Nearby Galaxy M60. M60, an elliptical galaxy located 16.5 Mpc away, has an active nucleus with a very low luminosity and an extremely low accretion rate. Its central supermassive black hole (SMBH) has a mass of M BH ~ 4.5 × 109 M ⊙ and a Schwarzschild radius corresponding to R S ~ 5.4 μas. To investigate the nature of its innermost radio nucleus, data from the Very Long Baseline Array (VLBA) at 4.4 and 7.6 GHz were reduced. The VLBA images reveal a compact component with total flux densities of ~20 mJy at both frequencies, a size of ≤0.27 mas (99.7% confidence level), about 0.022 pc (50 R S) at 7.6 GHz, and a brightness temperature of ≥6 × 109 K. This suggests that the observed centiparsec-scale compact core could be attributed to a nonthermal jet base or an advection-dominated accretion flow (ADAF) with nonthermal electrons. The extremely compact structure also supports the presence of an SMBH in the center. Our results indicate that M60 is a promising target for broadband very long baseline interferometry observations at millimeter wavelengths to probe ADAF scenarios and tightly constrain the potential photon ring (about 28 μas) around its SMBH.

Keywords: Supermassive black holes, Radio cores, Jets, Very long baseline interferometry, Galaxy accretion disks, Schwarzschild radius, Low-luminosity active galactic nuclei
Red Giant Rotational Inversion Kernels Need Nonlinear Surface Corrections. Asteroseismology is our only means of measuring the rotations of stars in their interiors, rather than at their surfaces. Some techniques for measurements of this kind-"rotational inversions"-require the shapes of linear response kernels computed from reference stellar models to be representative of those in the stars they are intended to match. This is not the case in evolved stars exhibiting gravitoacoustic mixed modes: we show that the action of the asteroseismic surface term-systematic errors in the modeling of near-surface layers-changes the shapes of their inversion kernels. Corrections for the surface term are not ordinarily considered necessary for rotational inversions. We show how this may have caused previous estimates of red-giant envelope rotation rates from mixed-mode asteroseismic inversions to have been unintentionally contaminated by core rotation as a result, with errors comparable to the entire reported estimates. We derive a mitigation procedure for this hitherto unaccounted systematic error, and demonstrate its viability and effectiveness. We recommend this mitigation be applied when revising existing rotational inversions. Finally, we discuss both the prospects for applying such mitigation to the harder problem of inversions for stellar structure (rather than rotation), as well as the broader implications of this systematic error with regard to the longstanding problem of internal angular momentum transport.

Keywords: Asteroseismology, Red giant stars, Stellar oscillations, Stellar rotation, Perturbation methods
First X-Ray Polarization Measurement Confirms the Low Black Hole Spin in LMC X-3. X-ray polarization is a powerful tool to investigate the geometry of accreting material around black holes, allowing independent measurements of the black hole spin and orientation of the innermost parts of the accretion disk. We perform X-ray spectropolarimetric analysis of an X-ray binary system in the Large Magellanic Cloud, LMC X-3, that hosts a stellar-mass black hole, known to be persistently accreting since its discovery. We report the first detection of the X-ray polarization in LMC X-3 with the Imaging X-ray Polarimetry Explorer, and find the average polarization degree (PD) of 3.2% ± 0.6% and a constant polarization angle of -42° ± 6° over the 2-8 keV range. Using accompanying spectroscopic observations by NICER, NuSTAR, and the Neil Gehrels Swift observatories, we confirm previous measurements of the black hole spin via the X-ray continuum method, a ≈ 0.2. From polarization analysis only, we found consistent results with low black hole spin, with an upper limit of a &lt; 0.7 at a 90% confidence level. A slight increase in the PD with energy, similar to other black hole X-ray binaries in the soft state, is suggested from the data but with a low statistical significance.

Keywords: Accretion, Black hole physics, X-ray astronomy, X-ray binary stars, Spectropolarimetry, X-ray detectors, High mass x-ray binary stars, X-ray observatories, Astrophysical black holes