Sazuna/UAT_keywords huggingface dataset:
Search for Alignment of Disk Orientations in Nearby Star-forming Regions: Lupus, Taurus, Upper Scorpius, ρ Ophiuchi, and Orion. Spatial correlations among protoplanetary disk orientations carry unique information on physics of multiple-star formation processes. We select five nearby star-forming regions that comprise a number of protoplanetary disks with spatially resolved images with ALMA and Hubble Space Telescope, and we search for the mutual alignment of the disk axes. Specifically, we apply the Kuiper test to examine the statistical uniformity of the position angle (PA: the angle of the major axis of the projected disk ellipse measured counterclockwise from the north) distribution. The disks located in the star-forming regions, except the Lupus clouds, do not show any signature of the alignment, supporting the random orientation. Rotational axes of 16 disks with spectroscopic measurement of PA in the Lupus III cloud, a subregion of the Lupus field, however, exhibit a weak and possible departure from the random distribution at a 2σ level, and the inclination angles of the 16 disks are not uniform as well. Furthermore, the mean direction of the disk PAs in the Lupus III cloud is parallel to the direction of its filament structure and approximately perpendicular to the magnetic field direction. We also confirm the robustness of the estimated PAs in the Lupus clouds by comparing the different observations and estimators based on three different methods, including sparse modeling. The absence of the significant alignment of the disk orientation is consistent with the turbulent origin of the disk angular momentum. Further observations are required to confirm/falsify the possible disk alignment in the Lupus III cloud.

Keywords: Interferometers, Protoplanetary disks, Astrostatistics, Molecular clouds
A Systematic Study on the Rise Time-Peak Luminosity Relation for Bright Optical Transients Powered by Wind Shock Breakout. A number of astrophysical transients originating from stellar explosions are powered by the collision of the ejected material with the circumstellar medium, which efficiently produces thermal radiation via shock dissipation. We investigate how such interaction-powered transients are distributed in the peak bolometric luminosity versus the rise time phase space. Taking advantage of less time-consuming one-dimensional simulations with spherical symmetry, we calculated more than 500 models with different circumstellar mass and radius, ejecta mass and energy, and chemical compositions. The peak bolometric luminosity, the total radiated energy, and the rise time of the interaction-powered emission are measured for each simulated light curve. We consider how these characteristic quantities are determined as a function of the model parameters and discuss possible implications for the observed populations of (potential) interaction-powered transients, such as Type IIn supernovae and fast blue optical transients.

Keywords: Hydrodynamics, Stellar mass loss, Circumstellar matter, Shocks, Supernovae
Line Oscillator Strengths for the {{{c}}_{4}}({') 1}{{{\Sigma }}_{{u}}}(+}(4)-{{X}}({1)) {{{\Sigma }}_{{g}}}(+}(0\mbox{-) 7) Absorption Bands of N<SUB>2</SUB>. Theoretical absorption oscillator strengths for rotational lines of the ${{{\rm{c}}}_{4}}^{{\prime} 1}{{{\rm{\Sigma }}}_{{\rm{u}}}}^{+}(4)$ - ${{\rm{X}}}^{1}{{{\rm{\Sigma }}}_{{\rm{g}}}}^{+}$ (0-7) bands of N2, which are relevant to analyze the spectra of the atmospheres of the Earth, Titan, and Mars, are reported. The known interaction between the ${{{\rm{c}}}_{4}}^{{\prime} 1}{{{\rm{\Sigma }}}_{{\rm{u}}}}^{+}(4)$ and ${{{\rm{c}}}_{3}}^{1}{{{\rm{\Pi }}}_{{\rm{u}}}}^{+}(4)$ Rydberg states and the ${{\rm{b}}}^{{\prime} 1}{{{\rm{\Sigma }}}_{{\rm{u}}}}^{+}(13)$ valence state has been dealt with through an appropriate rovibronic energy matrix. Deviations in the intensity distribution of the rotational lines from considerations based on Hönl-London factors have been found for each of the studied bands. Emission branching ratios for the above bands and lifetimes of the rotational levels of the v = 4 level of the ${{{\rm{c}}}_{4}}^{{\prime} 1}{{{\rm{\Sigma }}}_{{\rm{u}}}}^{+}$ state are also reported.

Keywords: Molecular spectroscopy, Line intensities, Radiative processes
The VLA-COSMOS 3 GHz Large Project: Evolution of Specific Star Formation Rates out to z ∼ 5. We provide a coherent, uniform measurement of the evolution of the logarithmic star formation rate (SFR)-stellar mass (M*) relation, called the main sequence (MS) of star-forming galaxies , for star-forming and all galaxies out to $z\sim 5$ . We measure the MS using mean stacks of 3 GHz radio-continuum images to derive average SFRs for ∼ 200,000 mass-selected galaxies at z &gt; 0.3 in the COSMOS field. We describe the MS relation by adopting a new model that incorporates a linear relation at low stellar mass (log(M*/M☉) &lt; 10) and a flattening at high stellar mass that becomes more prominent at low redshift (z &lt; 1.5). We find that the SFR density peaks at 1.5 &lt; z &lt; 2, and at each epoch there is a characteristic stellar mass (M* = 1-4 × 1010M☉) that contributes the most to the overall SFR density. This characteristic mass increases with redshift, at least to z ∼ 2.5. We find no significant evidence for variations in the MS relation for galaxies in different environments traced by the galaxy number density at 0.3 &lt; z &lt; 3, nor for galaxies in X-ray groups at z ∼ 0.75. We confirm that massive bulge-dominated galaxies have lower SFRs than disk-dominated galaxies at a fixed stellar mass at z &lt; 1.2. As a consequence, the increase in bulge-dominated galaxies in the local star-forming population leads to a flattening of the MS at high stellar masses. This indicates that "mass quenching" is linked with changes in the morphological composition of galaxies at a fixed stellar mass.

Keywords: Galaxy environments, Extragalactic radio sources, Galaxy bulges, Galaxy evolution, Radio continuum emission, Galaxy quenching
Magnetohydrodynamics with Post-Newtonian Corrections. Using the fully nonlinear and exact perturbation formulation with magnetohydrodynamics (MHD) in the Minkowski background, we derive first-order, post-Newtonian (1PN) equations without imposing the slicing (temporal gauge) condition. The 1PN-MHD formulation is complementary to our recently presented fully relativistic MHD combined with 0PN gravity available only in the maximal slicing. We present the 1PN-MHD equations in two gauge conditions previously used in the literature and provide gauge transformation relations between different gauges. We derive the PN effects on MHD waves in a static homogeneous medium.

Keywords: Relativity, Magnetohydrodynamics, Astrophysical fluid dynamics, Plasma astrophysics
Physical Implications of the Subthreshold GRB GBM-190816 and Its Associated Subthreshold Gravitational-wave Event. The LIGO/Virgo and Fermi collaborations recently reported a possible joint detection of a subthreshold gravitational-wave (GW) event and a subthreshold gamma-ray burst (GRB), GBM-190816, that occurred 1.57 s after the merger. We perform an independent analysis of the publicly available data and investigate the physical implications of this potential association. By carefully studying the following properties of GBM-190816 using Fermi/GBM data, including signal-to-noise ratio, duration, f-parameter, spectral properties, energetic properties, and its compliance with some GRB statistical correlations, we confirm that this event is likely a typical short GRB. Assuming its association with the subthreshold GW event, the inferred luminosity is ${1.47}_{-1.04}^{+3.40}\times {10}^{49}$ erg s-1. Based on the available information of the subthreshold GW event, we infer the mass ratio q of the compact binary as $q={2.26}_{-1.43}^{+2.75}$ (90% confidence interval) according to the reported range of luminosity distance. If the heavier compact object has a mass &gt;3 solar masses, q can be further constrained to $q={2.26}_{-0.12}^{+2.75}$ . The leading physical scenario invokes an NS-BH merger system with the NS tidally disrupted. Within this scenario, we constrain the physical properties of such a system (including mass ratio q, the spin parameters, and the observer's viewing angle) to produce a GRB. The GW data may also allow an NS-BH system with no tidal disruption of the NS (the plunge events) or a BH-BH merger. We apply the charged compact binary coalescence theory (for both a constant charge and an increasing charge for the merging members) to derive the model parameters to account for GBM-190816 and found that the required parameters are extreme. Finally, we argue that the fact that the observed GW-GRB delay timescale is comparable to that of GW170817/GRB 170817A suggests that the GW-GRB time delay of these two cases is mainly defined by the timescale for the jet to propagate to the energy dissipation/GRB emission site.

Keywords: Neutron stars, Gamma-ray bursts, Black holes, Relativistic jets, Gravitational waves, Compact objects, Gamma-ray transient sources
Effects of Electron Temperature Anisotropy on Proton-beam Instability in the Solar Wind. Solar wind observations often show that the drift velocity of a proton beam relative to a background proton decreases with the heliocentric distance. Proton-beam instability has been suggested to play an important role in the deceleration of the proton-beam velocity; the effects of electron temperature anisotropy on the proton-beam instability have not been examined. Based on a general kinetic dispersion relation solver for magnetized plasma (PDRK), we investigate the effects of electron temperature anisotropy on the oblique Alfvén/ion-cyclotron (A/IC) and parallel magnetosonic/whistler (M/W) instabilities driven by proton beams in the solar wind. The results show that the growth rates, real frequencies, and threshold conditions for both instabilities are sensitive to the electron temperature anisotropy Te⊥/Te∣∣ and the parallel electron beta βe∣∣. In the low-beta regime with ${\beta }_{e| | }\lt {\beta }_{e| | }^{c}\simeq 0.5$ , where ${\beta }_{e| | }^{c}$ is a critical plasma beta for which the threshold velocities of both instabilities are equal, the growth rate of the oblique A/IC instability is weakly dependent on the electron temperature anisotropy. In the high-beta regime with ${\beta }_{e| | }\gt {\beta }_{e| | }^{c}$ , the growth rate of the parallel M/W instability increases with decreasing Te⊥/Te∣∣. Moreover, the threshold velocities of both instabilities are shifted to lower values as Te⊥/Te∣∣ decreases, especially for the parallel M/W instability in the regime with βe∣∣ ≥ 1. The theoretical results for the threshold velocity together with the observed parallel electron beta and/or electron temperature anisotropy are used to explain the observed proton-beam drift velocity in the solar wind.

Keywords: Space plasmas, Solar wind
Stellar Parameters for the First Release of the MaSTar Library: An Empirical Approach. We report the stellar atmospheric parameters for 7503 spectra contained in the first release of the Mapping Nearby Galaxies at Apache Point Observatory survey (MaNGA) stellar library (MaStar) in Sloan Digital Sky Survey DR15. The first release of MaStar contains 8646 spectra measured from 3321 unique stars, each covering the wavelength range 3622-10354 Å with a resolving power of R ∼ 1800. In this work, we first determined the basic stellar parameters: effective temperature (Teff), surface gravity (log g), and metallicity ([Fe/H]), which best fit the data using an empirical interpolator based on the Medium-resolution Isaac Newton Telescope library of empirical spectra (MILES), as implemented by the University of Lyon Spectroscopic analysis Software package. While we analyzed all 8646 spectra from the first release of MaStar, since MaStar has a wider parameter-space coverage than MILES, not all of these fits are robust. In addition, not all parameter regions covered by MILES yield robust results, likely due to the nonuniform coverage of the parameter space by MILES. We tested the robustness of the method using the MILES spectra itself and identified a proxy based on the local density of the training set. With this proxy, we identified 7503 MaStar spectra with robust fitting results. They cover the range from 3179 to 20,517 K in effective temperature (Teff), from 0.40 to 5.0 in surface gravity (log g), and from -2.49 to +0.73 in metallicity ([Fe/H]).

Keywords: Surveys, Chemical abundances, Astronomical reference materials, Astronomical techniques, Spectroscopy, Radial velocity, Stellar atmospheres
Direct Measurement of the Solar-wind Taylor Microscale Using MMS Turbulence Campaign Data. Using the novel Magnetospheric Multiscale (MMS) mission data accumulated during the 2019 MMS Solar Wind Turbulence Campaign, we calculate the Taylor microscale (λT) of the turbulent magnetic field in the solar wind. The Taylor microscale represents the onset of dissipative processes in classical turbulence theory. However, an accurate estimation of the Taylor scale from spacecraft data is usually difficult due to low time cadence, the effect of time decorrelation, and other factors. Previous reports were based either entirely on the Taylor frozen-in approximation, which conflates time dependence, or were obtained using multiple data sets, which introduces sample-to-sample variation of plasma parameters, or had interspacecraft distances that were larger than the present study. The unique configuration of linear formation with logarithmic spacing of the four MMS spacecraft, during the campaign, enables a direct evaluation of the λT from a single data set, independent of the Taylor frozen-in approximation. A value of λT ≈ 7000 km is obtained, which is about three times larger than the previous estimates.

Keywords: Space plasmas, Magnetohydrodynamics, Interplanetary turbulence, Solar wind, Plasma astrophysics
Environmental Impact on Star-forming Galaxies in a z ∼ 0.9 Cluster during the Course of Galaxy Accretion. Galaxies change their properties as they assemble into clusters. In order to understand the physics behind that, we need to go back in time and observe directly what is occurring in galaxies as they fall into a cluster. We have conducted a narrowband and J-band imaging survey on a cluster CL1604-D at z = 0.923 using a new infrared instrument SWIMS installed at the Subaru Telescope. The narrowband filter, NB1261, matches to Hα emission from the cluster at z = 0.923. Combined with a wide range of existing data from various surveys, we have investigated galaxy properties in and around this cluster in great detail. We have identified 27 Hα emitters associated with the cluster. They have significant overlap with MIPS $24\,\mu {\rm{m}}$ sources and are located exclusively in the star-forming regime on the rest-frame UVJ diagram. We have identified two groups of galaxies near the cluster in the 2D spatial distribution and the phase-space diagram, which are likely to be in-falling to the cluster main body. We have compared various physical properties of star-forming galaxies, such as specific star formation rates (burstiness) and morphologies (merger) as a function of environment, cluster center, older group, younger group, and the field. As a result, a global picture has emerged on how the galaxy properties are altered as they assemble into a denser region. This includes the occurrence of mergers, enhancement of star formation activity, excursion to the dusty starburst phase, and eventual quenching to a passive phase.

Keywords: Galaxy clusters, Galaxy evolution, Galactic and extragalactic astronomy
Constraints of the Formation and Abundances of Methyl Carbamate, a Glycine Isomer, in Hot Corinos. Methyl carbamate CH3OC(O)NH2 is an isomer of glycine. Quantum chemical analyses show that methyl carbamate is a more stable isomer than glycine. Because of this, there could be a higher chance for methyl carbamate to exist in the interstellar medium (ISM) as compared to glycine. Despite immense searches, until now glycine has not been detected in the ISM; therefore, it is worthwhile to search its isomer methyl carbamate. In this paper, we present the constraints of methyl carbamate formation under the interstellar conditions. Large complex organic molecules are favorably produced in hot-corino environments of low-mass protostars. We for the first time carried out astrochemical modeling focusing on the formation of methyl carbamate in physical conditions similar to hot-corino objects. Consequently, we examined ALMA archival data for existing spectral line observations toward hot corinos NGC 1333 IRAS 4A2 and IRAS 16293B. Within the common spectral range toward these sources, we found three features are possibly related to the spectral transitions of methyl carbamate and consequently estimate the upper limit of column densities. Results of chemical modeling are consistent with the observational upper limit of estimated column density/abundance toward the sources. This may hint the validation of the proposed formation mechanism. Future observations using a telescope like ngVLA may confirm the presence of MC toward the hot corinos.

Keywords: Chemical abundances, Astrochemistry, Star formation, Low mass stars, Interstellar medium, Protostars, Interdisciplinary astronomy
Astrophysical Distance Scale: The AGB J-band Method. I. Calibration and a First Application. A near-infrared, color-selected subset of carbon-rich asymptotic giant branch (C-AGB) stars is found to have tightly constrained luminosities in the near-infrared J band. Based on JK photometry of some 3300 C-AGB stars in the bar of the Large Magellanic Cloud (LMC) we find that these stars have a constant absolute magnitude of $\langle {M}_{J}\rangle =-6.22$ mag, adopting the detached eclipsing binary (DEB) distance to the LMC of 18.477 ± 0.004 (stat) ± 0.026 (sys). Undertaking a second, independent calibration in the Small Magellanic Cloud, which also has a DEB geometric distance, we find $\langle {M}_{J}\rangle =-6.18\pm $ 0.01 (stat) ± 0.05 (sys) mag. For the LMC the scatter is ± 0.27 mag for single-epoch observations, (falling to ± 0.15 mag for multiple observations averaged over a window of more than one year). We provisionally adopt $\langle {M}_{J}\rangle =-6.20$ mag ± 0.01 (stat) ± 0.04 (sys) mag for the mean absolute magnitude of these stars. Applying this calibration to stars recently observed in the galaxy NGC 253, we determine a distance modulus of 27.66 ± 0.01(stat) ± 0.04 mag (syst), corresponding to a distance of 3.40 ± 0.06 Mpc (stat). This is in excellent agreement with the average tip of the red giant branch (TRGB) distance modulus of 27.68 ± 0.05 mag, assuming MI = -4.05 mag for the TRGB zero-point.

Keywords: Galaxy distances, Red giant branch, Galactic and extragalactic astronomy, Distance indicators, Asymptotic giant branch stars
Astrophysical Distance Scale. II. Application of the JAGB Method: A Nearby Galaxy Sample. We apply the near-infrared J-region asymptotic giant branch (JAGB) method, recently introduced by Madore &amp; Freedman, to measure the distances to 14 nearby galaxies out to 4 Mpc. We use the geometric detached eclipsing binary (DEB) distances to the LMC and SMC as independent zero-point calibrators. We find excellent agreement with previously published distances based on the tip of the red giant branch (TRGB): the JAGB distance determinations (including the LMC and SMC) agree in the mean to within ${\rm{\Delta }}(\mathrm{JAGB}-\mathrm{TRGB})\,=+0.025\pm 0.013$ mag, just over 1%, where the TRGB I-band zero-point is MI = -4.05 mag. With further development and testing, the JAGB method has the potential to provide an independent calibration of Type Ia supernovae, especially with the James Webb Space Telescope. The JAGB stars (with MJ = -6.20 mag) can be detected farther than the fainter TRGB stars, allowing greater numbers of calibrating galaxies for the determination of H0. Along with the TRGB and Cepheids, JAGB stars are amenable to theoretical understanding and further refined empirical calibration. A preliminary test shows little dependence, if any, of the JAGB magnitude on metallicity of the parent galaxy. These early results suggest that the JAGB method has considerable promise for providing high-precision distances to galaxies in the local universe that are independent of distances derived from the Leavitt Law and/or the TRGB method, and it has numerous and demonstrable advantages over the possible use of Mira variables.

Keywords: Galaxy distances, Red giant branch, Galactic and extragalactic astronomy, Distance indicators, Asymptotic giant branch stars
Spatially Resolved Ultraviolet Spectroscopy of the Great Dimming of Betelgeuse. The bright supergiant Betelgeuse (Alpha Orionis, HD 39801) experienced a visual dimming during 2019 December and the first quarter of 2020, reaching an historic minimum 2020 February 7-13. During 2019 September-November, prior to the optical dimming event, the photosphere was expanding. At the same time, spatially resolved ultraviolet spectra using the Hubble Space Telescope/Space Telescope Imaging Spectrograph revealed a substantial increase in the ultraviolet spectrum and Mg II line emission from the chromosphere over the southern hemisphere of the star. Moreover, the temperature and electron density inferred from the spectrum and C II diagnostics also increased in this hemisphere. These changes happened prior to the Great Dimming Event. Variations in the Mg II k-line profiles suggest material moved outwards in response to the passage of a pulse or acoustic shock from 2019 September through November. It appears that this extraordinary outflow of material from the star, likely initiated by convective photospheric elements, was enhanced by the coincidence with the outward motions in this phase of the ∼400 day pulsation cycle. These ultraviolet observations appear to provide the connecting link between the known large convective cells in the photosphere and the mass ejection event that cooled to form the dust cloud in the southern hemisphere imaged in 2019 December, and led to the exceptional optical dimming of Betelgeuse in 2020 February.

Keywords: Stellar chromospheres, M supergiant stars, Stellar atmospheres, Stellar mass loss
The Next Generation Virgo Cluster Survey (NGVS). XXX. Ultra-diffuse Galaxies and Their Globular Cluster Systems. We present a study of ultra-diffuse galaxies (UDGs) in the Virgo Cluster based on deep imaging from the Next Generation Virgo Cluster Survey. Applying a new definition for the UDG class based on galaxy scaling relations, we define samples of 44 and 26 UDGs using expansive and restrictive selection criteria, respectively. Our UDG sample includes objects that are significantly fainter than previously known UDGs: i.e., more than half are fainter than $\langle \mu {\rangle }_{e}\sim 27.5$ mag arcsec-2. The UDGs in Virgo's core region show some evidence for being structurally distinct from "normal" dwarf galaxies, but this separation disappears when considering the full sample of galaxies throughout the cluster. UDGs are more centrally concentrated in their spatial distribution than other Virgo galaxies of similar luminosity, while their morphologies demonstrate that at least some UDGs owe their diffuse nature to physical processes—such as tidal interactions or low-mass mergers—that are at play within the cluster environment. The globular cluster (GC) systems of Virgo UDGs have a wide range in specific frequency (SN), with a higher mean SN than "normal" Virgo dwarfs, but a lower mean SN than Coma UDGs at fixed luminosity. Their GCs are predominantly blue, with a small contribution from red clusters in the more massive UDGs. The combined GC luminosity function is consistent with those observed in dwarf galaxies, showing no evidence of being anomalously luminous. The diversity in their morphologies and their GC properties suggests no single process has given rise to all objects within the UDG class. Based on the available evidence, we conclude that UDGs are simply those systems that occupy the extended tails of the galaxy size and surface brightness distributions.

Keywords: Globular star clusters, Nucleated dwarf galaxies, Dwarf galaxies, Early-type galaxies, Low surface brightness galaxies