Sazuna/UAT_keywords huggingface dataset:
ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP). I. Detection of New Hot Corinos with the ACA. We report the detection of four new hot corino sources, G211.47-19.27S, G208.68-19.20N1, G210.49-19.79W, and G192.12-11.10, from a survey study of Planck Galactic Cold Clumps in the Orion Molecular Cloud Complex with the Atacama Compact Array. Three sources had been identified as low-mass Class 0 protostars in the Herschel Orion Protostar Survey. One source in the λ Orionis region is first reported as a protostellar core. We have observed abundant complex organic molecules (COMs), primarily methanol but also other oxygen-bearing COMs (in G211.47-19.27S and G208.68-19.20N1) and the molecule of prebiotic interest NH2CHO (in G211.47-19.27S), signifying the presence of hot corinos. While our spatial resolution is not sufficient to resolve most of the molecular emission structure, the large line width and high rotational temperature of COMs suggest that they likely reside in the hotter and innermost region immediately surrounding the protostar. In G211.47-19.27S, the D/H ratio of methanol ([CH2DOH]/[CH3OH]) and the 12C/13C ratio of methanol ([CH3OH]/[13CH3OH]) are comparable to those of other hot corinos. Hydrocarbons and long-carbon-chain molecules such as c-C3H2 and HCCCN are also detected in the four sources, likely tracing the outer and cooler molecular envelopes.

Keywords: Interstellar molecules, Star forming regions, Astrochemistry, Low mass stars, Protostars
How Flow Isolation May Set the Mass Scale for Super-Earth Planets. Much recent work on planet formation has focused on the growth of planets by accretion of grains whose aerodynamic properties make them marginally coupled to the nebular gas, a theory commonly referred to as "pebble accretion." While the rapid growth rates of pebble accretion can ameliorate some problems in planet formation theory, they raise new concerns as well. A particular issue is the preponderance of observed planets that end their growth as "super-Earths" or "sub-Neptunes," with masses in the range 2-10 M⊕. Once planets reach this mass scale, growth by pebble accretion is so rapid that ubiquitously ending growth at super-Earth masses is difficult unless growth rates drop at this mass scale. In this work, we highlight this issue in detail using our previously published model of pebble accretion, and also propose a reason for this change in growth rate: feedback between the growing planet's atmosphere and the gas disk inhibits accretion of smaller particle sizes by forcing them to flow around the growing planet instead of being accreted. For reasonable fiducial disk parameters, this "flow isolation" will inhibit accretion of all available particle sizes once the planet reaches super-Earth masses. We also demonstrate that the characteristics of this "flow isolation mass" agree with previously published trends identified in the Kepler planets.

Keywords: Planetary system formation, Super Earths, Protoplanetary disks, Exoplanets
Is T Tauri North a "Classical" T Tauri Star?. We present high-resolution H- and K-band spectroscopic observations of the archetypal T Tauri star T Tau North. Synthetic spectral modeling is used to derive the K-band temperature, surface gravity, magnetic field strength, and rotational velocity for this star. The K-band spectroscopic temperature measured is ${T}_{K \mbox{-} \mathrm{band}}=3976\pm 90\,{\rm{K}}$ , which is $\sim 1000\,{\rm{K}}$ cooler than the temperature measured from optical observations. Our K-band temperature measurement for T Tau N is confirmed using equivalent-width line ratio versus temperature relations in the H band, from which a ${T}_{H \mbox{-} \mathrm{band}}=4085\pm 155\,{\rm{K}}$ is derived. This optical versus IR temperature difference is interpreted as cool or hot spots, or both, covering a significant part of the surface of T Tau N. The gravity derived for T Tau N, $\mathrm{log}g=3.45\pm 0.14$ , is lower than the gravity of nearly every other star in a sample of 24 classical T Tauri stars in Taurus. Combining these temperature and gravity results with magnetic stellar evolutionary models, we find the age of T Tau N to be less than 1 Myr old. These results suggest that T Tau N is in an earlier evolutionary stage than most classical T Tauri stars in Taurus, arguing that it is a protostar ejected from the embedded southern binary system shortly after its formation.

Keywords: High resolution spectroscopy, Starspots, Stellar magnetic fields, Pre-main sequence stars, Star formation, Radiative transfer, Spectroscopy, Protostars, Near infrared astronomy
A Large-scale, Regular Intergalactic Magnetic Field Associated with Stephan's Quintet?. Regular magnetic fields are frequently found within and in the outskirts of galaxies, but their presence, properties, and origin has not yet been established for galaxy groups. On the basis of broadband radio polarimetric imaging with the Westerbork Synthesis Radio Telescope, we made use of rotation measure synthesis to disentangle contributions from magnetic fields on various scales for several polarized radio sources inside, behind, or in the vicinity of Stephan's Quintet (HCG 92, SQ). We recognize the signature of a large-scale, genuinely regular, magnetized screen, seemingly constrained to the Quintet itself. Although we cannot exclude a contribution from the Milky Way, our analysis favors a magnetic structure within the SQ system. If indeed associated with the galaxy group in question, it would span a volume of at least 60 × 40 × 20 kpc and have a strength at least as high as that previously detected within large spiral galaxies. This field would then surpass the extent of any other known galactic, regular magnetic fields; have a considerable strength of a few microgauss; and would be the first known example of such a structure in a galaxy system other than a galaxy pair. Several other explanations are also presented and evaluated.

Keywords: Hickson compact group, Spectropolarimetry, Galaxy groups, Polarimetry, Extragalactic magnetic fields
Revisiting the Sun's Strong Differential Rotation along Radial Lines. Current state-of-the-art models of the solar convection zone consist of solutions to the Navier-Stokes equations in rotating, 3D spherical shells. Such models are highly sensitive to the choice of boundary conditions. Here we present two suites of simulations differing only in their outer thermal boundary condition, which is either one of fixed entropy (FE) or fixed flux (FF; corresponding to a fixed gradient in the entropy). We find that the resulting differential rotation is markedly different between the two sets. The FF simulations have strong differential rotation contrast and isocontours tilted along radial lines (in good agreement with the Sun's interior rotation revealed by helioseismology), whereas the FE simulations have weaker contrast and contours tilted in the opposite sense. We examine in detail the force balances in our models and find that the poleward transport of heat by Busse columns drives a thermal wind responsible for the different rotation profiles. We conclude that the Sun's strong differential rotation along radial lines may result from the solar emissivity being invariant with latitude (which is similar to the FF condition in our models) and the poleward transport of heat by Busse columns. In future work on convection in the solar context, we strongly advise modelers to use an FF outer boundary condition.

Keywords: Hydrodynamical simulations, Stellar convective zones, Solar differential rotation, Solar convective zone, von Zeipel theorem, Stellar rotation, Astrophysical fluid dynamics
Negative Magnetic Diffusivity β Replacing the α Effect in the Helical Dynamo. In the Sun, the converting process of a poloidal magnetic field (Bpol) from a toroidal field (Btor) is essential to sustaining the solar magnetic fields. However, the converting process, dominated by α and β effects, is not yet clearly understood. Conventional theories expect that the α effect should be quenched as the magnetic field grows. Also, plasma kinetic energy is thought to diffuse magnetic energy (positive β effect). Then, Bpol is supposed to decay resulting in the dissipation of Btor, followed by the diminishing dynamo process. But the solar magnetic field evolves periodically, as is observed. To solve this inconsistency between the theory and real nature, we first need to check if the α and β effects indeed evolve as the conventional theories expect. However, these effects are theoretically or conceptually inferred quantities, and their exact expressions are not yet known. So, instead of their incomplete formulas, we used more practical representations composed of large-scale magnetic helicity ${\overline{H}}_{M}\,(\equiv \overline{{\boldsymbol{A}}}\cdot \overline{{\boldsymbol{B}}})$ and energy ${\overline{E}}_{M}\,(\equiv {\overline{B}}^{2}/2)$ . We verified that the α effect quenches as the conventional theory expects. However, we also found that the β effect can be negative. This negative β apparently looks inconsistent with the conventional conclusion, but it can be a promising substitution for the decaying α effect. We discuss their physical bases and mechanisms using a field structure model supported by an analytic method. The model shows that the interaction between the poloidal velocity component (Upol) and nonlocally transferred magnetic field (B · ∇ U) induces a current density jind along with the magnetic field. Their combined structure yields magnetic helicity to the system, which is the α effect. However, Upol can also interact with the locally transferred magnetic field, i.e., Upol × (- U · ∇ B) inducing a current density jdiff. This current density can produce additional magnetic helicity (negative β effect) to the system. Simultaneously, the toroidal component Utor with - U · ∇ B leads to the usual positive β effect, which diffuses the magnetic field. Finally, using the negative β effect, we show how the plasma motion is suppressed in a helically forced dynamo system where Lorentz force (J × B) apparently looks negligible.

Keywords: Solar magnetic fields, Magnetohydrodynamics, Plasma astrophysics, Solar dynamo
Spectral Features in Field-aligned Solar Wind Turbulence from Parker Solar Probe Observations. Parker Solar Probe (PSP) observed a large variety of Alfvénic fluctuations in the fast and slow solar wind flow during its two perihelia. The properties of Alfvénic solar wind turbulence have been studied for decades in the near-Earth environment. A spectral index of -5/3 or -2 for magnetic field fluctuations has been observed using spacecraft measurements, which can be explained by turbulence theories of nearly incompressible magnetohydrodynamics (NI MHD) or critical balance. In this study, a rigorous search of field-aligned solar wind is applied to PSP measurements for the first time, which yields two events in the apparently slow solar wind. The parallel spectra of the magnetic fluctuations in the inertial range show a ${k}_{\parallel }^{-5/3}$ power law. Probability distributions of the magnetic field show that these events are not contaminated by intermittent structures, which, according to previous studies, are known to modify spectral properties. The results presented here are consistent with spectral predictions from NI MHD theory and further deepen our understanding of the Alfvénic solar wind turbulence near the Sun.

Keywords: Interplanetary turbulence, Spectral index, Solar wind
Deep Learning Prediction of the Broad Lyα Emission Line of Quasars. We have employed a deep neural network, or deep learning, to predict the flux and the shape of the broad Lyα emission lines in the spectra of quasars. We use 17,870 high signal-to-noise ratio (S/N &gt; 15) quasar spectra from the Sloan Digital Sky Survey Data Release 14 to train the model and evaluate its performance. The Si IV, C IV, and C III] broad emission lines are used as the input to the neural network, and the model returns the predicted Lyα emission line as the output. We found that our neural-network model predicts quasars' continua around the Lyα spectral region with ∼6%-12% precision and ≲1% bias. Our model can be used to estimate the H I column density of eclipsing and ghostly damped Lyα (DLA) absorbers, as the presence of the DLA absorption in these systems strongly contaminates the flux and the shape of the quasar continuum around the Lyα spectral region. The model could also be used to study the state of the intergalactic medium during the epoch of reionization.

Keywords: Neural networks, Astronomy data analysis, Quasar absorption line spectroscopy, Intergalactic medium
Hurricane Genesis is Favorable on Terrestrial Exoplanets Orbiting Late-type M Dwarf Stars. Hurricanes are one of the most extreme storm systems that occur on Earth, characterized by strong rainfall and fast winds. The terrestrial exoplanets that will be characterized with future infrared space telescopes orbit M dwarf stars. As a result, the best observable terrestrial exoplanets have vastly different climates from Earth, with a large dayside-to-nightside irradiation contrast and relatively slow rotation. Hurricanes may affect future observations of terrestrial exoplanets because they enhance the vertical transport of water vapor and could influence ocean heat transport. In this work, we explore how the environment of terrestrial exoplanets orbiting M dwarf stars affects the favorability of hurricane genesis (formation). To do so, we apply metrics developed to understand hurricane genesis on Earth to three-dimensional climate models of ocean-covered exoplanets orbiting M dwarf stars. We find that hurricane genesis is most favorable on intermediate-rotating tidally locked terrestrial exoplanets with rotation periods of ∼8-10 days. As a result, hurricane genesis is most favorable for terrestrial exoplanets in the habitable zones of late-type M dwarf stars. The peak in the favorability of hurricane genesis at intermediate rotation occurs because sufficient spin is required for hurricane genesis, but the vertical wind shear on fast-rotating terrestrial exoplanets disrupts hurricane genesis. We find that hurricane genesis is less favorable on slowly rotating terrestrial exoplanets, which agrees with previous work. Future work using simulations that resolve hurricane genesis and evolution can test our expectations for how the environment affects the favorability of hurricane genesis on tidally locked terrestrial exoplanets.

Keywords: Extrasolar rocky planets, Habitable planets, Exoplanet atmospheres, Atmospheric circulation
The Effect of Bars on the Ionized ISM: Optical Emission Lines from Milky Way Analogs. Gas interior to the bar of the Milky Way has recently been shown to be the closest example of a low-ionization (nuclear) emission region (LI(N)ER) in the universe. To better understand the nature of this gas, a sample of face-on galaxies with integral field spectroscopy is used to study the ionized gas conditions of 240 barred and 250 nonbarred galaxies, focusing on those that are most similar to the Milky Way. Strong optical line emission of [N II] λ6584, Hα, [O III] λ5007, and Hβ are used to diagnose the dominant ionization mechanisms of gas across galaxies and the Galaxy via Baldwin-Phillips-Terlevich diagrams. Barred galaxies show a strong suppression of star formation and an increase in composite and LI(N)ER-like spectra in their inner regions when compared with similar nonbarred counterparts. This effect is lessened in galaxies of very low ( ${\mathrm{log}}_{10}({M}_{\star }/{M}_{\odot })\lesssim 10.4$ ) or very high ( ${\mathrm{log}}_{10}({M}_{\star }/{M}_{\odot })\gtrsim 11.1$ ) total stellar mass. Bar masks from Galaxy Zoo:3D show the bar's nonaxisymmetric effect on the ionized gas and help predict the face-on distribution of ionized gas conditions near the bar of the Milky Way.

Keywords: Interstellar line emission, Interstellar atomic gas, Interstellar radiation field, LINER galaxies, Interstellar medium, Barred spiral galaxies, Milky Way Galaxy
IceCube Search for High-energy Neutrino Emission from TeV Pulsar Wind Nebulae. Pulsar wind nebulae (PWNe) are the main gamma-ray emitters in the Galactic plane. They are diffuse nebulae that emit nonthermal radiation. Pulsar winds, relativistic magnetized outflows from the central star, shocked in the ambient medium produce a multiwavelength emission from the radio through gamma-rays. Although the leptonic scenario is able to explain most PWNe emission, a hadronic contribution cannot be excluded. A possible hadronic contribution to the high-energy gamma-ray emission inevitably leads to the production of neutrinos. Using 9.5 yr of all-sky IceCube data, we report results from a stacking analysis to search for neutrino emission from 35 PWNe that are high-energy gamma-ray emitters. In the absence of any significant correlation, we set upper limits on the total neutrino emission from those PWNe and constraints on hadronic spectral components.

Keywords: Neutrino astronomy, High energy astrophysics
The Effect of Misalignment between the Rotation Axis and Magnetic Field on the Circumstellar Disk. The formation of circumstellar disks is investigated using three-dimensional resistive magnetohydrodynamic simulations in which the initial prestellar cloud has a misaligned rotation axis with respect to the magnetic field. We examine the effects of (i) the initial angle difference between the global magnetic field and the cloud rotation axis (θ0) and (ii) the ratio of the thermal to gravitational energy (α0). We study 16 models in total and calculate the cloud evolution until ∼5000 yr after protostar formation. Our simulation results indicate that an initial nonzero θ0 (&gt;0) promotes disk formation but tends to suppress outflow driving for models that are moderately gravitationally unstable, α0 ≲ 1. In these models, a large-sized rotationally supported disk forms and a weak outflow appears, in contrast to a smaller disk and strong outflow in the aligned case (θ0 = 0). Furthermore, we find that when the initial cloud is highly unstable with small α0, the initial angle difference θ0 does not significantly affect the disk formation and outflow driving.

Keywords: Magnetohydrodynamics, Stellar jets, Star formation, Protoplanetary disks, Protostars, Magnetic fields
Stellar Characterization of Keck HIRES Spectra with The Cannon. To accurately interpret the observed properties of exoplanets, it is necessary to first obtain a detailed understanding of host star properties. However, physical models that analyze stellar properties on a per-star basis can become computationally intractable for sufficiently large samples. Furthermore, these models are limited by the wavelength coverage of available spectra. We combine previously derived spectral properties from the Spectroscopic Properties of Cool Stars (SPOCS) catalog with generative modeling using The Cannon to produce a model capable of deriving stellar parameters ( $\mathrm{log}g$ , Teff, and $v\sin i$ ) and 15 elemental abundances (C, N, O, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, and Y) for stellar spectra observed with Keck Observatory's High Resolution Echelle Spectrometer (HIRES). We demonstrate the high accuracy and precision of our model, which takes just ∼3 s to classify each star, through cross-validation with pre-labeled spectra from the SPOCS sample. Our trained model, which takes continuum-normalized template spectra as its inputs, is publicly available at https://github.com/malenarice/keckspec. Finally, we interpolate our spectra and employ the same modeling scheme to recover labels for 477 stars using archival stellar spectra obtained prior to Keck's 2004 detector upgrade, demonstrating that our interpolated model can successfully predict stellar labels for different spectrographs that have (1) sufficiently similar systematics and (2) a wavelength range that substantially overlaps with that of the post-2004 HIRES spectra.

Keywords: High resolution spectroscopy, Stellar properties, Exoplanets, Stellar abundances, Astrostatistics techniques, Chemical abundances, Stellar physics, Spectroscopy, Radial velocity, Stellar spectral lines, Metallicity, Catalogs
Morphological Classification of the Convective Regimes in Rotating Stars. We present a set of numerical simulations that model the convection zones of solar-like stars. With this suite of numerical experiments, we explore how the nature of the convective structures transitions through a series of morphological regimes as the reduced Rayleigh number increases. Convection first manifests as a belt of rotationally aligned, convective, Taylor columns that circumscribes the equator. As the supercriticality increases, the poles begin to convect, initially in a cellular form, but eventually a plumy form emerges. Finally, at extremely high values of the Rayleigh number, a weakly rotating regime is achieved with antisolar differential rotation, i.e., the equator rotates more slowly than the poles. For all of these regimes, we provide theoretical and empirical scaling relations that summarize how global quantities—such as the bulk Rossby number and Reynolds number—scale with the Rayleigh and Ekman numbers. We demonstrate that a Rossby number based on the properties of the thermal boundary layer that clings to the outer surface of the convection zone works particularly well to predict the transition to antisolar differential rotation.

Keywords: Stellar interiors, Stellar convective zones, Solar rotation, Solar differential rotation, Solar interior, Stellar dynamics, Stellar physics, Solar physics, Stellar rotation
Ion-scale Current Structures in Short Large-amplitude Magnetic Structures. We investigate electric current structures in Short Large-Amplitude Magnetic Structures (SLAMS) in the terrestrial ion foreshock region observed by the Magnetospheric Multiscale mission. The structures with intense currents ( $| J| \sim 1\,\mu {\rm{A}}\,{{\rm{m}}}^{-2}$ ) have scale lengths comparable to the local ion inertial length (di). One current structure type is a current sheet due to the magnetic field rotation of the SLAMS, and a subset of these current sheets can exhibit reconnection features including the electron outflow jet and X-line-type magnetic topology. The di-scale current sheet near the edge of a SLAMS propagates much more slowly than the overall SLAMS, suggesting that it may result from compression. The current structures also exist as magnetosonic whistler waves with fci &lt; f &lt; flh, where fci and flh are the ion cyclotron frequency and the lower-hybrid frequency, respectively. The field rotations in the current sheets and whistler waves generate comparable $| J| $ and energy conversion rates. Electron heating is clearly observed in one whistler packet embedded in a larger-scale current sheet of the SLAMS, where the parallel electric field and the curvature drift opposite to the electric field energize electrons. The results give insight about the thin current structure generation and energy conversion at thin current structures in the shock transition region.

Keywords: Shocks, Solar magnetic reconnection
Rotation of Two Micron All Sky Survey Clumps in Molecular Clouds. We have analyzed the rotational properties of 12 clumps using 13CO (1-0) and C18O (1-0) maps of the Five College Radio Astronomy Observatory 13.7 m radio telescope. The clumps, located within molecular clouds, have radii (R) in the range of 0.06-0.27 pc. The direction of clump elongation is not correlated with the direction of the velocity gradient. We measured the specific angular momentum (J/M) to be between 0.0022-0.025 pc km s-1 based on 13CO images, and between 0.0025-0.021 pc km s-1 based on C18O images. The consistency of J/M based on different tracers indicates the 13CO and C18O in dense clumps trace essentially the same material despite significantly different opacities. We also found that J/M increases monotonically as a function of R in power-law form, $J/M\,\propto \,{R}^{1.58\pm 0.11}$ . The ratio between rotation energy and gravitational energy, β, ranges from 0.0012 to 0.018. The small values of β imply that rotation alone is not sufficient to support the clump against gravitational collapse.

Keywords: Interstellar molecules, Interstellar dynamics, Interstellar emissions, Interstellar medium, Intercloud medium