Sazuna/UAT_keywords huggingface dataset:
Creating the Radius Gap without Mass Loss. The observed exoplanet population features a gap in the radius distribution that separates the smaller super-Earths (≲1.7 Earth radii) from the larger sub-Neptunes (~1.7-4 Earth radii). While mass-loss theories can explain many of the observed features of this radius valley, it is difficult to reconcile them with the potentially rising population of terrestrials beyond orbital periods of ~30 days. We investigate the ability of gas accretion during the gas-poor phase of disk evolution to reproduce both the location of the observed radius gap and the existence of long-period terrestrial planets. Updating the analytic scaling relations of gas accretion rate accounting for the shrinking of the bound radius by hydrodynamic effects and deriving a more realistic disk temperature profile, we find that the late-stage gas accretion alone is able to carve out the observed radius gap, with slopes R gap ∝ P -0.096 and ${R}_{\mathrm{gap}}\propto {M}_{\star }^{0.15}$ for top-heavy; and R gap ∝ P -0.089 and ${R}_{\mathrm{gap}}\propto {M}_{\star }^{0.22}$ for bottom-heavy core mass distributions, in good agreement with observations. The general morphology of the primordial radius gap is stable against a range of disk gas density and disk accretion rate with the latter affecting mostly the population of large planets (≳3-4 R ⊕). The peaks and valleys in the radius distribution were likely set in place primordially while post-formation mass loss further tunes the exoplanetary population. We provide potential observational tests that may be possible with TESS, PLATO, and Roman Space Telescope.

Keywords: Exoplanet astronomy, Exoplanet evolution, Exoplanet formation
Testing the Retrieval of Inner Disk Water Enrichment with Spitzer/IRS and JWST/MIRI. Planet formation by pebble accretion requires an efficient inward flux of icy pebbles to explain the many mini-Neptunes and super-Earths discovered by Kepler within 1 au. Recently, hints of large-scale pebble migration have been found in the anticorrelation between the line ratio of water-to-other volatiles detected in medium-resolution (R ~ 700) Spitzer/IRS spectra and the dust disk radius measured at millimeter wavelengths with the Atacama Large Millimeter Array. Here, we select three disks in Taurus that span the range of measured line flux ratios (a factor of ~5) and dust disk radii (1 order of magnitude) and model their Spitzer/IRS spectra assuming gas in local thermodynamic equilibrium to retrieve the water column density in their inner disks. We find that, at the Spitzer/IRS resolution and sensitivity, large uncertainties in the retrieved column densities preclude resolving the expected difference of a factor of ~5 in water abundance. Next, we simulate higher-resolution (~3000) JWST/MIRI spectra at the signal-to-noise ratio of ~100, which will be obtained via the Guaranteed Time and General Observation programs and apply the same retrieval approach used with Spitzer/IRS spectra. We show that the improved resolution and sensitivity of JWST/MIRI significantly reduce the uncertainties in the retrieved water column densities and will enable quantifying the difference in the inner water column of small versus large dust disks.

Keywords: Molecular gas, Molecular spectroscopy, Infrared astronomy, Pre-main sequence stars, Protoplanetary disks, Circumstellar disks
X-Ray Photoabsorption of Density-sensitive Metastable States in Ne VII, Fe XXII, and Fe XXIII. Metastable states of ions can be sufficiently populated in absorbing and emitting astrophysical media, enabling spectroscopic plasma-density diagnostics. Long-lived states appear in many isoelectronic sequences with an even number of electrons, and can be fed at large rates by various photonic and electronic mechanisms. Here, we experimentally investigate beryllium-like and carbon-like ions of neon and iron that have been predicted to exhibit detectable features in astrophysical soft X-ray absorption spectra. An ion population generated and excited by electron impact is subjected to highly monochromatic X-rays from a synchrotron beamline, allowing us to identify Kα transitions from metastable states. We compare their energies and natural line widths with state-of-the-art theory and benchmark level population calculations at electron densities of 1010.5 cm-3.

Keywords: Line positions, Atomic physics, Laboratory astrophysics, Plasma astrophysics, Ionization, Spectroscopy, Atomic data benchmarking, Line intensities
Multiwavelength Observations of MWC 297: Constraints on Disk Inclination and Mass Outflow. MWC 297 is a young, early-type star driving an ionized outflow and surrounded by warm, entrained dust. Previous analyses of near- and mid-IR interferometric images suggest that the emission at these wavelengths arises from a compact accretion disk with a moderate (i &lt; 40°) inclination. We have obtained 5-40 μm images of MWC 297 with FORCAST on SOFIA, as well as near-infrared spectra acquired with SpeX on the IRTF and radio data obtained with the VLA and BIMA, and supplemented these with archival data from Herschel/PACS and SPIRE. The FORCAST images, combined with the VLA data, indicate that the outflow lobes are aligned nearly north-south and are well separated. Simple geometrical modeling of the FORCAST images suggests that the disk driving the outflow has an inclination of 55° ± 5°, in disagreement with the results of the interferometric analyses. Analysis of the SpeX data, with a wind model, suggests the mass-loss rate is on the order of $6.0{\pm }_{1.7}^{3.7}\times {10}^{-7}{M}_{\odot }\,{\mathrm{yr}}^{-1}$ and the extinction to the source is ${A}_{V}\sim 8.1{\pm }_{1.5}^{2.5}$ mag. We have combined our data with values from the literature to generate the spectral energy distribution of the source from 0.35 μm to 6 cm and estimate the total luminosity. We find the total luminosity to be about 7900 L ☉, if we include emission from an extended region around the star, only slightly below that expected for a B1.5V star. The reddening must be produced by dust along the line of sight, but distant from the star.

Keywords: Stellar accretion disks, Herbig Ae/Be stars, Young stellar objects, Pre-main sequence stars
Near-infrared Spectroscopy of a Massive Young Stellar Object in the Direction toward the Galactic Center: XCN and Aromatic C-D Features. We report near-infrared (2.5-5 μm) long-slit (~30″) spectroscopy of a young stellar object in the direction toward the Galactic center with the Infrared Camera on board the AKARI satellite. The present target is suggested to be AFGL 2006 based on its very red color and close location. The spectra show strong absorption features of H2O and CO2 ices, and emission of H I Brα recombination line and the 3.3 μm band, the latter of which originates from polycyclic aromatic hydrocarbons (PAHs) or materials containing PAHs. The spectra show a broad, complex absorption feature at 4.65 μm, which is well explained by a combination of absorption features of CO ice, CO gas, and XCN, and H I Pfβ emission. The spectra also indicate excess emission at 4.4 μm. The characteristics of the spectra suggest that the object is a massive young stellar object. The XCN feature shows a good correlation with the Brα emission, suggesting that the photolysis by ultraviolet photons plays an important role in the formation of the XCN carriers, part of which are attributed to OCN-. The 4.4 μm emission shows a good correlation with the 3.3 μm PAH emission, providing supporting evidence that it comes from the aromatic C-D stretching vibration. The formation of OCN- is of importance for the formation process of prebiotic matter in the interstellar medium (ISM), while the detection of aromatic C-D emission provides valuable information on the deuteration process of PAHs in the ISM and implications on the hiding site of the missing deuterium in the ISM.

Keywords: Interstellar dust, Polycyclic aromatic hydrocarbons, Ice formation, Young stellar objects, Interstellar medium
AGN Selection and Demographics in GOODS-S/HUDF from X-Ray to Radio. We present a comprehensive census of the active galactic nuclei (AGNs) in the GOODS-S/HUDF region from the X-ray to the radio, covering both the obscured and unobscured populations. This work includes a robust analysis of the source optical to mid-IR spectral energy distributions (SEDs) featuring (semi)empirical AGN and galaxy dust emission models and Bayesian fitting techniques, ultra-deep Very Large Array 3 and 6 GHz observations, and an integrated analysis of various AGN selection techniques, including X-ray properties, UV to mid-IR SED analysis, optical spectral features, mid-IR colors, radio-loudness and spectral slope, and AGN variability. In total, we report ~900 AGNs over the ~170 arcmin2 3D-HST GOODS-S footprint, which has doubled the AGN number identified in the previous X-ray sample, with ~26% of our sample undetected in the deepest Chandra image. With a summary of AGN demographics from different selection methods, we find that no one single band or technique comes close to selecting a complete AGN sample despite the great depth of the data in GOODS-S/HUDF. We estimate the yields of various approaches and explore the reasons for incompleteness. We characterize the statistical properties, such as source number density, obscuration fraction, and luminosity function of the AGN sample in this field, and discuss their immediate implications. We also provide some qualitative predictions of the AGN sample that might be discovered by the upcoming JWST surveys.

Keywords: X-ray active galactic nuclei, Active galactic nuclei, Infrared galaxies, Radio active galactic nuclei, High-redshift galaxies
Locating Hidden Exoplanets in ALMA Data Using Machine Learning. Exoplanets in protoplanetary disks cause localized deviations from Keplerian velocity in channel maps of molecular line emission. Current methods of characterizing these deviations are time consuming,and there is no unified standard approach. We demonstrate that machine learning can quickly and accurately detect the presence of planets. We train our model on synthetic images generated from simulations and apply it to real observations to identify forming planets in real systems. Machine-learning methods, based on computer vision, are not only capable of correctly identifying the presence of one or more planets, but they can also correctly constrain the location of those planets.

Keywords: Exoplanet astronomy, Exoplanet detection methods, Protoplanetary disks, Hydrodynamical simulations
Observed Rate Variations in Superflaring G-type Stars. Flare occurrence on the Sun is highly variable, exhibiting both short-term variation due to the emergence and evolution of active regions, and long-term variation from the solar cycle. On solar-like stars, more energetic stellar flares (superflares) have been observed, and it is of interest to determine whether the observed rates of superflare occurrence exhibit similar variability to solar flares. We analyze 274 G-type stars using data from the Transiting Exoplanet Survey Satellite and identify seven stars which exhibit statistically significant changes in the rate of superflare occurrence by fitting a piecewise constant-rate model with the Bayesian blocks algorithm. We investigate the properties of these stars and their flaring rates, and discuss the possible reasons for the low number of stars with detectable rate variation.

Keywords: Stellar rotation, Stellar flares, G dwarf stars, Stellar activity
Detection of the Extended γ-Ray Emission from the High Galactic Latitude Calvera's SNR Candidate. We report the extended GeV γ-ray emission that is spatially associated with the high Galactic latitude supernova remnant (SNR) candidate-Calvera's SNR with the Pass 8 data recorded by the Fermi Large Area Telescope. The γ-ray spectrum of Calvera's SNR between 100 MeV and 1 TeV shows an evident (~3.4σ) spectral curvature at several tens of GeV. The multiwavelength data can be fitted with either a leptonic model or a hadronic one. However, the leptonic model exhibits inconsistency between the flat radio spectrum and the hard GeV γ-ray spectrum of Calvera's SNR. For the hadronic model, the spectral index of protons should be harder than 1.6 and the total energy of protons is fitted to be more than one order of magnitude higher than the explosion energy of a typical supernova, which also challenges the hadronic model. The evident spectral curvature and the absence of nonthermal X-ray emission from Calvera's SNR makes it to be an interesting source bridging young-aged SNRs with bright nonthermal X-ray emission and old-aged SNRs interacting with molecular clouds.

Keywords: Supernova remnants, Gamma-ray astronomy, Gamma-ray sources
Extreme Nature of Four Blue-excess Dust-obscured Galaxies Revealed by Optical Spectroscopy. We report optical spectroscopic observations of four blue-excess dust-obscured galaxies (BluDOGs) identified by the Subaru Hyper Suprime-Cam. BluDOGs are a subclass of dust-obscured galaxies (DOGs; defined with the extremely red color (i - [22])AB ≥ 7.0; Toba et al., showing a significant flux excess in the optical g and r bands over the power-law fits to the fluxes at the longer wavelengths. Noboriguchi et al. have suggested that BluDOGs may correspond to the blowing-out phase involved in a gas-rich major-merger scenario. However, the detailed properties of BluDOGs are not understood because of the lack of spectroscopic information. In this work, we carry out deep optical spectroscopic observations of four BluDOGs using Subaru/FOCAS and VLT/FORS2. The obtained spectra show broad emission lines with extremely large equivalent widths, and a blue wing in the C IV line profile. The redshifts are between 2.2 and 3.3. The averaged rest-frame equivalent widths of the C IV lines are 160 ± 33 Å, ~7 times higher than the average of a typical type 1 quasar. The FWHMs of their velocity profiles are between 1990 and 4470 km s-1, and their asymmetric parameters are 0.05 and 0.25. Such strong C IV lines significantly affect the broadband magnitudes, which are partly the origin of the blue excess seen in the spectral energy distribution of BluDOGs. Their estimated supermassive black hole masses are 1.1 × 108 &lt; M BH/M ☉ &lt;5.5 × 108. The inferred Eddington ratios of the BluDOGs are higher than 1 (1.1 &lt; λ Edd &lt; 3.8), suggesting that the BluDOGs are in a rapidly evolving phase of supermassive black holes.

Keywords: Quasars, Active galaxies, Galaxy evolution, Infrared galaxies, Spectroscopy
Quantum Chemical Computations of Gas-phase Glycolaldehyde Deuteration and Constraints on Its Formation Route. Despite the detection of numerous interstellar complex organic molecules (iCOMs) for decades, it is still a matter of debate whether they are synthesized in the gas phase or on the icy surface of interstellar grains. In the past, molecular deuteration has been used to constrain the formation paths of small and abundant hydrogenated interstellar species. More recently, the deuteration degree of formamide, one of the most interesting iCOMs, has also been explained with the hypothesis that it is formed by the gas-phase reaction NH2 + H2CO. In this paper, we aim at using molecular deuteration to constrain the formation of another iCOM, glycolaldehyde, which is an important prebiotic species. More specifically, we have performed dedicated electronic structure and kinetic calculations to establish the glycolaldehyde deuteration degree in relation to that of ethanol, which is its possible parent species according to the suggestion of Skouteris et al. We found that the abundance ratio of the species containing one D atom over the all-protium counterpart depends on the produced D isotopomer and varies from 0.9 to 0.5. These theoretical predictions compare extremely well with the monodeuterated isotopomers of glycolaldehyde and that of ethanol measured toward the solar-like protostar IRAS 16293-2422, supporting the hypothesis that glycolaldehyde could be produced in the gas phase for this source. In addition, the present work confirms that the deuterium fractionation of iCOMs cannot be simply anticipated based on the deuterium fractionation of the parent species but necessitates a specific study, as already shown for the case of formamide.

Keywords: Astrochemistry
Inferring Maps of the Sun's Far-side Unsigned Magnetic Flux from Far-side Helioseismic Images Using Machine Learning Techniques. Accurate modeling of the Sun's coronal magnetic field and solar wind structures requires inputs of the solar global magnetic field, including both the near and far sides, but the Sun's far-side magnetic field cannot be directly observed. However, the Sun's far-side active regions are routinely monitored by helioseismic imaging methods, which only require continuous near-side observations. It is therefore both feasible and useful to estimate the far-side magnetic-flux maps using the far-side helioseismic images despite their relatively low spatial resolution and large uncertainties. In this work, we train two machine-learning models to achieve this goal. The first machine-learning training pairs simultaneous Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager-observed magnetic-flux maps and SDO/Atmospheric Imaging Assembly-observed extreme ultraviolet (EUV) 304 Å images, and the resulting model can convert 304 Å images into magnetic-flux maps. This model is then applied to the STEREO-observed far-side 304 Å images, available for about 4.3 yr, for the far-side magnetic-flux maps. These EUV-converted magnetic-flux maps are then paired with simultaneous far-side helioseismic images for a second machine-learning training, and the resulting model can convert far-side helioseismic images into magnetic-flux maps. These helioseismically derived far-side magnetic-flux maps, despite their limitations in spatial resolution and accuracy, can be routinely available on a daily basis, providing useful magnetic information on the Sun's far side using only the near-side observations.

Keywords: Helioseismology, Space weather, Solar active regions, Solar magnetic fields
Deflection of O<SUB>2</SUB> <SUP>+</SUP> Ion Flow by Magnetic Fields in the Martian Ionosphere. The effect of the Martian crustal magnetic field on ion escape is the focus of considerable interest. Directions of magnetic fields near Mars determined by the interaction between Mars' crustal and interplanetary magnetic fields have been suggested to play a significant role on ion transport around Mars. In this study we investigate the physical mechanism of deflection of ${{\rm{O}}}_{2}^{+}$ ion flow in two typical magnetic field orientations at the horizontal plane in the Martian ionosphere by performing 3D multifluid Hall magnetohydrodynamic simulations. Cross validation of the simulation results from two cases with the G110 crustal field model and equivalent source dipole model reveals that due to the Hall electric force, ${{\rm{O}}}_{2}^{+}$ ion flow tends to be accelerated eastwards in the region occupied by outward magnetic fields, and westwards in the region with inward magnetic fields. These results are helpful for understanding the impact of magnetic fields on the deflection of ionospheric ions in the Martian space environment.

Keywords: Magnetic anomalies, Mars, Solar-planetary interactions, Magnetohydrodynamics
A New Flaring Black Widow Candidate and Demographics of Black Widow Millisecond Pulsars in the Galactic Field. We present the discovery of a new optical/X-ray source likely associated with the Fermi γ-ray source 4FGL J1408.6-2917. Its high-amplitude periodic optical variability, large spectroscopic radial-velocity semiamplitude, evidence for optical emission lines and flaring, and X-ray properties together imply the source is probably a new black widow millisecond pulsar binary. We compile the properties of the 41 confirmed and suspected field black widows, finding a median secondary mass of 0.027 ± 0.003 M ☉. Considered jointly with the more massive redback millisecond pulsar binaries, we find that the "spider" companion mass distribution remains strongly bimodal, with essentially zero systems having companion masses of between ~0.07 and 0.1 M ☉. X-ray emission from black widows is typically softer and less luminous than in redbacks, consistent with less efficient particle acceleration in the intrabinary shock in black widows, excepting a few systems that appear to have more efficient "redback-like" shocks. Together black widows and redbacks dominate the census of the fastest spinning field millisecond pulsars in binaries with known companion types, making up ≳80% of systems with P spin &lt; 2 ms. Similar to redbacks, the neutron star masses in black widows appear on average significantly larger than the canonical 1.4 M ☉, and many of the highest-mass neutron stars claimed to date are black widows with M NS ≳ 2.1 M ☉. Both of these observations are consistent with an evolutionary picture where spider millisecond pulsars emerge from short orbital period progenitors that had a lengthy period of mass transfer initiated while the companion was on the main sequence, leading to fast spins and high masses.

Keywords: Millisecond pulsars
An Interpretable Machine-learning Framework for Modeling High-resolution Spectroscopic Data. Comparison of échelle spectra to synthetic models has become a computational statistics challenge, with over 10,000 individual spectral lines affecting a typical cool star échelle spectrum. Telluric artifacts, imperfect line lists, inexact continuum placement, and inflexible models frustrate the scientific promise of these information-rich data sets. Here we debut an interpretable machine-learning framework blasé that addresses these and other challenges. The semiempirical approach can be viewed as "transfer learning"-first pretraining models on noise-free precomputed synthetic spectral models, then learning the corrections to line depths and widths from whole-spectrum fitting to an observed spectrum. The auto-differentiable model employs back-propagation, the fundamental algorithm empowering modern deep learning and neural networks. Here, however, the 40,000+ parameters symbolize physically interpretable line profile properties such as amplitude, width, location, and shape, plus radial velocity and rotational broadening. This hybrid data-/model-driven framework allows joint modeling of stellar and telluric lines simultaneously, a potentially transformative step forward for mitigating the deleterious telluric contamination in the near-infrared. The blasé approach acts as both a deconvolution tool and semiempirical model. The general-purpose scaffolding may be extensible to many scientific applications, including precision radial velocities, Doppler imaging, chemical abundances for Galactic archeology, line veiling, magnetic fields, and remote sensing. Its sparse-matrix architecture and GPU acceleration make blasé fast. The open-source PyTorch-based code blase includes tutorials, Application Programming Interface documentation, and more. We show how the tool fits into the existing Python spectroscopy ecosystem, demonstrate a range of astrophysical applications, and discuss limitations and future extensions. * Open-source code at https://github.com/gully/blase.

Keywords: High resolution spectroscopy, Astronomy data modeling, Brown dwarfs, Earth atmosphere, Radial velocity, Deconvolution, Calibration, Atomic spectroscopy, GPU computing, Stellar photospheres, Maximum likelihood estimation, Stellar spectral lines