Sazuna/UAT_keywords huggingface dataset:
First Detection of Submillimeter-wave [<SUP>13</SUP>C I] <SUP>3</SUP> P <SUB>1</SUB>-<SUP>3</SUP> P <SUB>0</SUB> Emission in a Gaseous Debris Disk of 49 Ceti with ALMA. We have detected the submillimeter-wave fine-structure transition (3 P 1-3 P 0) of 13C, [13C I], in the gaseous debris disk of 49 Ceti with the Atacama Large Millimeter/submillimeter Array (ALMA). Recently, the [C I] 3 P 1-3 P 0 emission has been spatially resolved in this source with ALMA. In this data set, the F = 3/2-1/2 hyperfine component of [13C I], which is blueshifted by 2.2 km s-1 from the normal species line, [C I], has been identified in the outer part of the 49 Ceti disk, thanks to the narrow velocity widths of the gas components. The [C I]/[13C I] line intensity ratio is found to be 12 ± 3, which is significantly lower than the 12C/13C abundance ratio of 77 in the interstellar medium. This result clearly reveals that the [C I] emission is optically thick in 49 Ceti at least partly, as speculated by the previous work. As far as we know, this is the first detection of [13C I] 3 P 1-3 P 0 emission at 492 GHz not only in debris disks but also in the interstellar medium.

Keywords: Observational astronomy, Circumstellar matter, Debris disks, Submillimeter astronomy
Organosulfur Compounds Formed by Sulfur Ion Bombardment of Astrophysical Ice Analogs: Implications for Moons, Comets, and Kuiper Belt Objects. Carbon, hydrogen, nitrogen, oxygen, and sulfur are the main elements involved in the solid-phase chemistry of various astrophysical environments. Among these elements, sulfur chemistry is probably the least well understood. We investigated whether sulfur ion bombardment within simple astrophysical ice analogs (originating from H2O:CH3OH:NH3, 2:1:1) could trigger the formation of complex organosulfur molecules. Over 1100 organosulfur (CHNOS) molecular formulas (12% of all assigned signals) were detected in resulting refractory residues within a broad mass range (from 100 to 900 amu, atomic mass unit). This finding indicates a diverse, rich and active sulfur chemistry that could be relevant for Kuiper Belt objects (KBO) ices, triggered by high-energy ion implantation. The putative presence of organosulfur compounds within KBO ices or on other icy bodies might influence our view on the search of habitability and biosignatures.

Keywords: Classical Kuiper belt objects, Laboratory astrophysics, Experimental techniques, Astrochemistry, Astrobiology, Trans-Neptunian objects, Comets
The Interstellar Object ’Oumuamua as a Fractal Dust Aggregate. The first known interstellar object ’Oumuamua exhibited a nongravitational acceleration that appeared inconsistent with cometary outgassing, leaving radiation pressure as the most likely force. Barring the alien lightsail hypothesis, an ultra-low density due to a fractal structure might also explain the acceleration of ’Oumuamua by radiation pressure. In this Letter we report a decrease in ’Oumuamua’s rotation period based on ground-based observations, and show that this spin-down can be explained by the YORP effect if ’Oumuamua is indeed a fractal body with the ultra-low density of 10-2 kg m-3. We also investigate the mechanical consequences of ’Oumuamua as a fractal body subjected to rotational and tidal forces, and show that a fractal structure can survive these mechanical forces.

Keywords: Two-body problem, Solid matter physics, Astrophysical dust processes, Protoplanetary disks, Interstellar dust processes, Apollo group
Determination of Transport Coefficients by Coronal Seismology of Flare-induced Slow-mode Waves: Numerical Parametric Study of a 1D Loop Model. Recent studies of a flaring loop oscillation event on 2013 December 28 observed by the Atmospheric Imaging Assembly of the Solar Dynamics Observatory have revealed the suppression of thermal conduction and significant enhancement of compressive viscosity in hot (∼10 MK) plasma. In this study we aim at developing a new coronal seismology method for determining the transport coefficients based on a parametric study of wave properties using a 1D nonlinear magnetohydrodynamics (MHD) loop model in combination with the linear theory. The simulations suggest a two-step scheme: we first determine the effective thermal conduction coefficient from the observed phase shift between temperature and density perturbations as this physical parameter is insensitive to the unknown viscosity; then from the loop model with the obtained thermal conduction coefficient, we determine the effective viscosity coefficient from the observed decay time using the parametric modeling. With this new seismology technique we are able to quantify the suppression of thermal conductivity by a factor of about 3 and the enhancement of viscosity coefficient by a factor of 10 in the studied flaring loop. Using the loop model with these refined transport coefficients, we study the excitation of slow magnetoacoustic waves by launching a flow pulse from one footpoint. The simulation can self-consistently produce the fundamental standing wave on a timescale in agreement with the observation.

Keywords: Solar coronal seismology, Solar flares, Solar extreme ultraviolet emission, Solar coronal loops, Solar coronal waves, Active solar corona
Rankine-Hugoniot Shock Conditions for Space and Astrophysical Plasmas Described by Kappa Distributions. This paper provides the set of Rankine-Hugoniot (R-H) jump conditions for shocks in space and astrophysical plasmas described by kappa, distributions. The characteristic result is the development of a new R-H condition that transforms the values of kappa upstream and downstream the shock. The kappa index parameterizes and labels kappa distributions, and it is necessary for characterizing the thermodynamics of space plasmas. This first approach is restricted to non-magnetized plasmas, and the whole achievement is derived by following first principles of statistical mechanics and thermodynamics. The results show that, depending on the shock strength, the kappa indices across the shock may decrease or increase, indicating cases of shock acceleration or deceleration, respectively.

Keywords: Space plasmas, Shocks, Plasma astrophysics, Heliosphere
Can Neutron-star Mergers Explain the r-process Enrichment in Globular Clusters?. Star-to-star dispersion of r-process elements has been observed in a significant number of old, metal-poor globular clusters (GCs). We investigate early-time neutron-star mergers as the mechanism for this enrichment. Through both numerical modeling and analytical arguments, we show that neutron-star mergers cannot be induced through dynamical interactions early in the history of the cluster, even when the most liberal assumptions about neutron-star segregation are assumed. Therefore, if neutron-star mergers are the primary mechanism for r-process dispersion in GCs, they likely result from the evolution of isolated, primordial binaries in the clusters. Through population modeling of double neutron-star progenitors, we find that most enrichment candidates are fast-merging systems that undergo a phase of mass transfer involving a naked He-star donor. Only models where a significant number of double neutron-star progenitors proceed through this evolutionary phase give rise to moderate fractions of GCs with enrichment; under various assumptions for the initial properties of GCs, a neutron-star merger with the potential for enrichment will occur in ∼15%-60% (∼30%-90%) of GCs if this phase of mass transfer proceeds stably (unstably). The strong anti-correlation between the pre-supernova orbital separation and post-supernova systemic velocity due to mass loss in the supernova leads to efficient ejection of most enrichment candidates from their host clusters. Thus, most enrichment events occur shortly after the double neutron stars are born. This Requires star-forming gas that can absorb the r-process ejecta to be present in the globular cluster 30-50 Myr after the initial burst of star formation. If scenarios for redistributing gas in GCs cannot act on these timescales, the number of neutron-star merger enrichment candidates drops severely, and it is likely that another mechanism, such as r-process enrichment from collapsars, is at play.

Keywords: Neutron stars, Globular star clusters, Binary stars, R-process, Stellar dynamics, Stellar evolution
The First Day in the Life of a Magnetar: Evolution of the Inclination Angle, Magnetic Dipole Moment, and Braking Index of Millisecond Magnetars during Gamma-Ray Burst Afterglows. The afterglow emission of some gamma-ray bursts (GRBs) shows a shallow decay (plateau) phase implying continuous injection of energy. The source of this energy is very commonly attributed to the spin-down power of a nascent millisecond magnetar. The magnetic dipole radiation torque is considered to be the mechanism causing the spin-down of the neutron star. This torque has a component working for the alignment of the angle between rotation and the magnetic axis, i.e., the inclination angle, which has been neglected in modeling GRB afterglow light curves. Here, we demonstrate the evolution of the inclination angle and magnetic dipole moment of nascent magnetars associated with GRBs. We constrain the initial inclination angle, magnetic dipole moment, and rotation period of seven magnetars by modeling the seven long-GRB afterglow light curves. We find that, in its first day, the inclination angle of a magnetar decreases rapidly. The rapid alignment of the magnetic and rotation axis may address the lack of persistent radio emission from mature magnetars. We also find that in three cases the magnetic dipole moments of magnetars decrease exponentially to a value a few times smaller than the initial value. The braking index of nascent magnetars, as a result of the alignment and magnetic dipole moment decline, is variable during the afterglow phase and always greater than three.

Keywords: Magnetars, Gamma-ray bursts
The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. I. Identifying and Characterizing the Protostellar Content of the OMC-2 FIR4 and OMC-2 FIR3 Regions. We present Atacama Large Millimeter/submillimeter Array (0.87 mm) and Very Large Array (9 mm) observations toward OMC-2 FIR4 and OMC-2 FIR3 within the Orion integral-shaped filament, thought to be two of the nearest regions of intermediate-mass star formation. We characterize the continuum sources within these regions on ∼40 au (0.″1) scales and associated molecular line emission at a factor of ∼30 better resolution than previous observations at similar wavelengths. We identify six compact continuum sources within OMC-2 FIR4, four in OMC-2 FIR3, and one additional source just outside OMC-2 FIR4. This continuum emission is tracing the inner envelope and/or disk emission on less than 100 au scales. HOPS-108 is the only protostar in OMC-2 FIR4 that exhibits emission from high-excitation transitions of complex organic molecules (e.g., methanol and other lines) coincident with the continuum emission. HOPS-370 in OMC-2 FIR3, with L ∼ 360 L ☉, also exhibits emission from high-excitation methanol and other lines. The methanol emission toward these two protostars is indicative of temperatures high enough to thermally evaporate it from icy dust grains; overall, these protostars have characteristics similar to hot corinos. We do not identify a clear outflow from HOPS-108 in 12CO, but we find evidence of interaction between the outflow/jet from HOPS-370 and the OMC-2 FIR4 region. A multitude of observational constraints indicate that HOPS-108 is likely a low- to intermediate-mass protostar in its main mass accretion phase and is the most luminous protostar in OMC-2 FIR4. The high-resolution data presented here are essential for disentangling the embedded protostars from their surrounding dusty environments and characterizing them.

Keywords: Star forming regions, Young stellar objects, Star formation, Interstellar medium, Protostars, Radio interferometry
Uncertainty Quantification in Sunspot Counts. Observing and counting sunspots constitutes one of the longest-running scientific experiments, with first observations dating back to Galileo (around 1610). Today the sunspot number (SN) time series acts as a benchmark of solar activity in a large range of physical models. An appropriate statistical modeling, adapted to the time series’ complex nature, is, however, still lacking. In this work, we provide the first comprehensive uncertainty quantification analysis of sunspot counts. We study three components: the number of sunspots (N  s ), the number of sunspot groups (N  g ), and the composite N  c , defined as {N}c:= {N}s+10{N}g. Those are reported by a network of observatories around the world and are corrupted by errors of various types. We use a multiplicative framework to provide, for these three components, an estimation of their error distribution in various regimes (short-term, long-term, minima of solar activity). We also propose a robust estimator for the underlying solar signal and fit density distributions that take into account intrinsic characteristics such as overdispersion, excess of zeros, and multiple modes. The estimation of the solar signal underlying the composite N  c  may be seen as a robust version of the International Sunspot Number (ISN), widely used as a proxy of solar activity. Therefore, our results on N  c  may help characterize the uncertainty on ISN as well. Our results pave the way for a future monitoring of the observatories in quasi-real time, with the aim of alerting the observers when they start deviating from the network and preventing large drifts from occurring.

Keywords: Sunspot groups, Sunspot number, Model selection, Sunspots, Mixture model
Multiwavelength Stereoscopic Observation of the 2013 May 1 Solar Flare and CME. A M-class behind-the-limb solar flare on 2013 May 1 (SOL2013-05-01T02:32), accompanied by a (∼400 km s-1) coronal mass ejection (CME), was observed by several space-based observatories with different viewing angles. We investigated the RHESSI-observed occulted hard X-ray (HXR) emissions that originated at least 0.1 {R}{{S}} above the flare site. Emissions below ∼10 keV revealed a hot, extended (11 MK, &gt;60″) thermal source from the escaping CME core, with densities around 109 cm-3. In such a tenuous hot plasma, ionization times scales are several minutes, consistent with the nondetection of the hot CME core in SDO/AIA’s 131 Å filter. The nonthermal RHESSI source originated from an even larger area (∼100″) at lower densities (108 cm-3) located above the hot core, but still behind the CME front. This indicates that the observed part of the nonthermal electrons are not responsible for heating the CME core. Possibly the hot core was heated by nonthermal electrons before it became visible from Earth, meaning that the unocculted part of the nonthermal emission likely originates from a more tenuous part of the CME core, where nonthermal electrons survive long enough to became visible from Earth. Simultaneous HXR spectra from the Mars Odyssey mission, which viewed the flare on disk, indicated that the number of nonthermal electrons &gt;20 keV within the high coronal source is ∼0.1%-0.5% compared with the number within the chromospheric flare ribbons. The detection of high coronal HXR sources in this moderate size event suggests that such sources are likely a common feature within solar eruptive events.

Keywords: Active solar corona, Solar flares, Solar coronal mass ejections, X-ray sources
Dwarfs or Giants? Stellar Metallicities and Distances from ugrizG Multiband Photometry. We present a new fully data-driven algorithm that uses photometric data from the Canada-France Imaging Survey (CFIS; u), Pan-STARRS 1 (PS1; griz), and Gaia (G) to discriminate between dwarf and giant stars and to estimate their distances and metallicities. The algorithm is trained and tested using the Sloan Digital Sky Survey (SDSS)/SEGUE spectroscopic data set and Gaia photometric/astrometric data set. At [Fe/H] &lt; -1.2, the algorithm succeeds in identifying more than 70% of the giants in the training/test set, with a dwarf contamination fraction below 30% (with respect to the SDSS/SEGUE data set). The photometric metallicity estimates have uncertainties better than 0.2 dex when compared with the spectroscopic measurements. The distances estimated by the algorithm are valid out to a distance of at least ∼80 kpc without requiring any prior on the stellar distribution and have fully independent uncertainties that take into account both random and systematic errors. These advances allow us to estimate these stellar parameters for approximately 12 million stars in the photometric data set. This will enable studies involving the chemical mapping of the distant outer disk and the stellar halo, including their kinematics using the Gaia proper motions. This type of algorithm can be applied in the southern hemisphere to the first release of LSST data, thus providing an almost complete view of the external components of our Galaxy out to at least ∼80 kpc. Critical to the success of these efforts will be ensuring well-defined spectroscopic training sets that sample a broad range of stellar parameters with minimal biases. A catalog containing the training/test set and all relevant parameters within the public footprint of CFIS is available online.

Keywords: Stellar photometry, Distance measure, Milky Way stellar halo, Red giant stars, Metallicity, Milky Way Galaxy
Search for Sources of Astrophysical Neutrinos Using Seven Years of IceCube Cascade Events. Low-background searches for astrophysical neutrino sources anywhere in the sky can be performed using cascade events induced by neutrinos of all flavors interacting in IceCube with energies as low as ∼1 TeV. Previously we showed that, even with just two years of data, the resulting sensitivity to sources in the southern sky is competitive with IceCube and ANTARES analyses using muon tracks induced by charge current muon neutrino interactions—especially if the neutrino emission follows a soft energy spectrum or originates from an extended angular region. Here, we extend that work by adding five more years of data, significantly improving the cascade angular resolution, and including tests for point-like or diffuse Galactic emission to which this data set is particularly well suited. For many of the signal candidates considered, this analysis is the most sensitive of any experiment to date. No significant clustering was observed, and thus many of the resulting constraints are the most stringent to date. In this paper we will describe the improvements introduced in this analysis and discuss our results in the context of other recent work in neutrino astronomy.

Keywords: High energy astrophysics, Neutrino astronomy, Cosmic ray sources
UVIT Open Cluster Study. II. Detection of Extremely Low Mass White Dwarfs and Post-Mass Transfer Binaries in M67. A detailed study of the UV-bright stars in the old open star cluster M67 is presented based on the far-UV observations using the Ultra Violet Imaging Telescope (UVIT) on ASTROSAT. The UV and UV-optical color-magnitude diagrams (CMDs), along with overlaid isochrones, are presented for the member stars, which include blue straggler stars (BSSs), triple systems, white dwarfs (WDs), and spectroscopic binaries. The CMDs suggest the presence of excess UV flux in many members, which could be extrinsic or intrinsic to them. We construct multiwavelength spectral energy distributions (SEDs) using photometric data from the UVIT, Gaia DR2, Two Micron All Sky Survey, and Wide-Field Infrared Survey Explorer surveys, along with optical photometry. We fitted model SEDs to seven WDs and find that four of them have mass &gt;0.5 M ⊙ and cooling age of less than 200 Myr, thus demanding BSS progenitors. SED fits to 23 stars detect extremely low mass (ELM) WD companions to WOCS2007, WOCS6006, and WOCS2002 and a low-mass WD to WOCS3001, which suggest these to be post-mass transfer (MT) systems. Twelve sources with possible WD companions need further confirmation. Nine sources have X-ray and excess UV flux, possibly arising out of stellar activity. This study demonstrates that UV observations are key to detecting and characterizing the ELM WDs in nondegenerate systems, which are ideal test beds to explore the formation pathways of these peculiar WDs. The increasing detection of post-MT systems among BSSs and main-sequence stars suggests a strong MT pathway and stellar interactions in M67.

Keywords: Hertzsprung Russell diagram, White dwarf stars, Open star clusters, Ultraviolet astronomy, Blue straggler stars
Habitability and Spectroscopic Observability of Warm M-dwarf Exoplanets Evaluated with a 3D Chemistry-Climate Model. Planets residing in circumstellar habitable zones offer us the best opportunities to test hypotheses of life’s potential pervasiveness and complexity. Constraining the precise boundaries of habitability and its observational discriminants is critical to maximizing our chances at remote life detection with future instruments. Conventionally, calculations of the inner edge of the habitable zone (IHZ) have been performed using both 1D radiative-convective and 3D general circulation models. However, these models lack interactive 3D chemistry and do not resolve the mesosphere and lower thermosphere region of the upper atmosphere. Here, we employ a 3D high-top chemistry-climate model (CCM) to simulate the atmospheres of synchronously rotating planets orbiting at the inner edge of habitable zones of K- and M-dwarf stars (between T eff = 2600 and 4000 K). While our IHZ climate predictions are in good agreement with general circulation model studies, we find noteworthy departures in simulated ozone and HOx photochemistry. For instance, climates around inactive stars do not typically enter the classical moist greenhouse regime even with high (≳10-3 mol mol-1) stratospheric water vapor mixing ratios, which suggests that planets around inactive M-stars may only experience minor water-loss over geologically significant timescales. In addition, we find much thinner ozone layers on potentially habitable moist greenhouse atmospheres, as ozone experiences rapid destruction via reaction with hydrogen oxide radicals. Using our CCM results as inputs, our simulated transmission spectra show that both water vapor and ozone features could be detectable by instruments NIRSpec and MIRI LRS on board the James Webb Space Telescope.

Keywords: Extrasolar rocky planets, Astrobiology, Exoplanet atmospheres, Stellar activity
Intensity Gradients Technique: Synergy with Velocity Gradients and Polarization Studies. Magnetic fields are ubiquitous in the interstellar medium but notoriously difficult to study through observation. Making use of the advances in our understanding of MHD turbulence and turbulent reconnection, the velocity gradients technique (VGT) was suggested and successfully applied to study magnetic fields utilizing spectroscopic data. Applying the tools developed for the VGT to intensity statistics, we introduce the intensity gradients technique (IGT) as a complementary tool that can be used synergistically with the VGT. In this paper, we apply the IGT to a diffuse H I region selected from the GALFA-H I survey and compare the intensity gradient (IG) maps with those obtained using velocity gradients, as well as Planck polarization measurements. We demonstrate the possibility of using the IGT and VGT for both studying the magnetic field and identifying shocks in the diffuse interstellar medium. We also explore the ability of the IGT in locating self-gravitating regions and calculating Alfvénic Mach numbers, both alone and in combination with the VGT and polarimetry. We compare the IGT with the histogram of relative orientation, which utilizes IGs to characterize the relative orientation of column density structures and local magnetic fields.

Keywords: Interstellar magnetic fields, Interstellar dynamics, Interstellar medium