adsabs/SciX_UAT_keywords huggingface dataset:
Multispacecraft Remote Sensing and In Situ Observations of the 2020 November 29 Coronal Mass Ejection and Associated Shock: From Solar Source to Heliospheric Impacts

We investigate the source eruption, propagation and expansion characteristics, and heliospheric impacts of the 2020 November 29 coronal mass ejection (CME) and associated shock, using remote sensing and in situ observations from multiple spacecraft. A potential-field source-surface model is employed to examine the coronal magnetic fields surrounding the source region. The CME and associated shock are tracked from the early stage to the outer corona using extreme ultraviolet and white light observations. Forward models are applied to determine the structures and kinematics of the CME and the shock near the Sun. The shock shows an ellipsoidal structure, expands in all directions, and encloses the whole Sun as viewed from both SOHO and STEREO A, which results from the large expansion of the CME flux rope and its fast acceleration. The structure and potential impacts of the shock are mainly determined by its radial and lateral expansions. The CME and shock arrive at Parker Solar Probe and STEREO A. Only based on the remote sensing observations, it is difficult to predict whether and when the CME/shock would arrive at the Earth. Combining Wind in situ measurements and Wang-Sheeley-Arge-ENLIL simulation results, we confirm that the far flank of the CME (or the CME leg) arrives at the Earth with no shock signature. These results highlight the importance of multipoint remote sensing and in situ observations for determining the heliospheric impacts of CMEs.

Keywords: interplanetary shocks; solar wind; solar coronal mass ejections
Spatial Variations of Magnetic Field along Active Galactic Nuclei Jets on Sub-parsec to Megaparsec Scales

We report the systematic analysis of knots, hotspots, and lobes in 57 active galactic nuclei (AGNs) to investigate the variation of the magnetic field along the jet from the sub-parsec base to the terminus on kiloparsec-to-megaparsec scales. Expanding the number of radio/X-ray samples in the work of Kataoka & Stawarz, we analyzed the data in 12 FR I and 30 FR II radio galaxies, 12 quasars, and three BL Lac objects, which contained 76 knots, 42 hotspots, and 29 radio lobes. We first derived the equipartition magnetic fields in the cores and then estimated those in various jet components by assuming Best ∝ d-1, where d is the distance from the jet base. On the other hand, the magnetic field in large-scale jets (knots, hotspots, and lobes), Beq, can be estimated from the observed flux and spatial extent under the equipartition hypothesis. We show that the magnetic field decreases as the distance along the jet increases, but generally in a more gentle way than ∝d-1. The increase in Beq/Best at large d may suggest the deceleration of the jet downstream, but there is no difference between FR I and FR II jets. Moreover, the magnetic fields in the hotspots are systematically larger than those in knots and lobes. Finally, we applied the same analysis to knots and lobes in Centaurus A to check whether the above discussion will hold even in a single jet source.

Keywords: magnetic fields; radio jets; fanaroff-riley radio galaxies; quasars; jets
Redshift Evolution of Green Valley Galaxies in Different Environments from the Hyper Suprime-Cam Survey

Green valley galaxies represent the population that is likely to transition from star-forming to quiescent phases. To investigate the role of the environment in quenching star formation, we use the wide-field data from the Hyper Suprime-Cam Strategic Subaru Proposal survey to quantify the frequency of green valley galaxies in different environments and their redshift evolution. We find that the green valley fraction, in general, is less than 20% in any redshift and environment. The green valley fraction, when normalized to the total population, is higher in the field than that in groups or clusters and decreases with decreasing redshift and increasing mass. The lower fraction of transitional galaxies in denser environments could be a consequence of the lack of star-forming galaxies, which could be the progenitors of green valley galaxies. To assess the effect of the environment on star formation quenching, we define the effective green valley fraction as the ratio of the number of green valley galaxies to that of nonquiescent galaxies only. The effective green valley fraction for field galaxies is lower than that for group or cluster galaxies, which reveals a strong positive mass dependence and mild redshift evolution. Moreover, the specific star formation rate is reduced by 0.1-0.3 dex in groups or clusters. Our results thus imply that an ongoing slow quenching process has been acting in the dense environment since z ∼ 1.

Keywords: galaxy clusters; galaxy groups; large-scale structure of the universe; astronomy data analysis; green valley galaxies
Search for Neutrinos in Coincidence with Gravitational Wave Events from the LIGO-Virgo O3a Observing Run with the Super-Kamiokande Detector

The Super-Kamiokande detector can be used to search for neutrinos in time coincidence with gravitational waves detected by the LIGO-Virgo Collaboration (LVC). Both low-energy (7-100 MeV) and high-energy (0.1-105 GeV) samples were analyzed in order to cover a very wide neutrino spectrum. Follow-ups of 36 (out of 39) gravitational waves reported in the GWTC-2 catalog were examined; no significant excess above the background was observed, with 10 (24) observed neutrinos compared with 4.8 (25.0) expected events in the high-energy (low-energy) samples. A statistical approach was used to compute the significance of potential coincidences. For each observation, p-values were estimated using neutrino direction and LVC sky map; the most significant event (GW190602_175927) is associated with a post-trial p-value of 7.8% (1.4σ). Additionally, flux limits were computed independently for each sample and by combining the samples. The energy emitted as neutrinos by the identified gravitational wave sources was constrained, both for given flavors and for all flavors assuming equipartition between the different flavors, independently for each trigger and by combining sources of the same nature.

Keywords: neutrino astronomy; gravitational wave astronomy; high energy astrophysics; black holes; compact objects; neutron stars; transient sources
Rotation of Solar Analogs Crossmatching Kepler and Gaia DR2

A major obstacle to interpreting the rotation period distribution for main-sequence stars from Kepler mission data has been the lack of a precise evolutionary status for these objects. We address this by investigating the evolutionary status based on Gaia Data Release 2 parallaxes and photometry for more than 30,000 Kepler stars with rotation period measurements. Many of these are subgiants and should be excluded in future work on dwarfs. We particularly investigate a 193-star sample of solar analogs and report newly determined rotation periods for 125 of these. These include 54 stars from a prior sample, of which we can confirm the periods for 50. The remainder are new, and 10 of them longer than a solar rotation period, suggesting that Sun-like stars continue to spin down on the main sequence past solar age. Our sample of solar analogs could potentially serve as a benchmark for future missions, such as PLAnetary Transits and Oscillations of stars, and emphasizes the need for additional astrometric, photometric, and spectroscopic information before interpreting the stellar populations and results from time series surveys.

Keywords: fundamental parameters of stars; stellar rotation; stellar activity; stellar photometry; stellar evolution; starspots
A Clear View of a Cloudy Brown Dwarf Companion from High-resolution Spectroscopy

Direct imaging studies have mainly used low-resolution spectroscopy (R ~ 20-100) to study the atmospheres of giant exoplanets and brown dwarf companions, but the presence of clouds has often led to degeneracies in the retrieved atmospheric abundances (e.g., carbon-to-oxygen ratio, metallicity). This precludes clear insights into the formation mechanisms of these companions. The Keck Planet Imager and Characterizer (KPIC) uses adaptive optics and single-mode fibers to transport light into NIRSPEC (R ~ 35,000 in the K band), and aims to address these challenges with high-resolution spectroscopy. Using an atmospheric retrieval framework based on petitRADTRANS, we analyze the KPIC high-resolution spectrum (2.29-2.49 μm) and the archival low-resolution spectrum (1-2.2 μm) of the benchmark brown dwarf HD 4747 B (m = 67.2 ± 1.8 M Jup, a = 10.0 ± 0.2 au, T eff ≈ 1400 K). We find that our measured C/O and metallicity for the companion from the KPIC high-resolution spectrum agree with those of its host star within 1σ-2σ. The retrieved parameters from the K-band high-resolution spectrum are also independent of our choice of cloud model. In contrast, the retrieved parameters from the low-resolution spectrum are highly sensitive to our chosen cloud model. Finally, we detect CO, H2O, and CH4 (volume-mixing ratio of log(CH4) = -4.82 ± 0.23) in this L/T transition companion with the KPIC data. The relative molecular abundances allow us to constrain the degree of chemical disequilibrium in the atmosphere of HD 4747 B, and infer a vertical diffusion coefficient that is at the upper limit predicted from mixing length theory.

Keywords: brown dwarfs; atmospheric composition; high resolution spectroscopy; high angular resolution; atmospheric clouds; exoplanet atmospheric composition
The Population of Compact Radio Sources in M17

We present a catalog of radio sources of the M17 region based on deep X-band radio observations centered at 10 GHz obtained with the Jansky Very Large Array in the A configuration. We detect a total of 194 radio sources, 12 of them extended and 182 compact. We find that a significant fraction (at least 40% in our catalog) have suspected gyrosynchrotron emission associated with stellar coronal emission. By comparing the radio luminosities of our sources with their X-ray counterparts, when available, we find that they are underluminous in X-rays with respect to the Güdel-Benz relation, but a correlation with a similar slope is obtained provided that only sources with evident nonthermal nature are selected from the sample compiled for the Orion Nebula Cluster (ONC) and M17. The comparison of M17 with the ONC and NGC 6334D-F leads to a similar luminosity function for the three regions, at least for the more luminous sources. However, the radio sources in M17 are three times more numerous compared to the other regions at a given luminosity and their spatial distribution differs from that of Orion. Moreover, an arc-shaped structure of 40″ in extent is observed in our map, identified previously as an ionizing front, with the cometary hypercompact source UC1 at its focus. Archival 1 mm ALMA data reveals compact emission coincident with the radio wavelength peak, possibly associated with a protostellar disk of the massive star exciting UC1.

Keywords: star forming regions; young stellar objects; radio source catalogs
Parallax Systematics and Photocenter Motions of Benchmark Eclipsing Binaries in Gaia EDR3

Previous analyses of various standard candles observed by the Gaia satellite have reported statistically significant systematics in the parallaxes that have improved from ∼250 μas in the first data release (DR1) to 50-80 μas in the second data release (DR2). Here we examine the parallaxes newly reported in the Gaia early third data release (EDR3) using the same sample of benchmark eclipsing binaries (EBs) we used to assess the DR1 and DR2 parallaxes. We find a mean offset of -37 ± 20 μas (Gaia - EB), which decreases to -15 ± 18 μas after applying the corrections recommended by the Gaia Mission team; global systematics in the Gaia parallaxes have clearly improved and are no longer statistically significant for the EB sample, which spans 5 ≲ G ≲ 12 in brightness and 0.03-3 kpc in distance. We also find that the Renormalized Unit Weight Error (RUWE) goodness-of-fit statistic reported in Gaia DR3 is highly sensitive to unresolved companions (tertiaries in the case of our EB sample) as well as to photocenter motion of the binaries themselves. RUWE is nearly perfectly correlated (r2 = 0.82) with photocenter motions down to ≲0.1 mas, and surprisingly this correlation exists entirely within the nominal "good" RUWE range of 1.0-1.4. This suggests that RUWE values even slightly greater than 1.0 may signify unresolved binaries in Gaia, and that the RUWE value can serve as a quantitative predictor of the photocenter motion.

Keywords: eclipsing binary stars; stellar parallax; stellar distance
Three-dimensional Geometry of the Electron-scale Magnetic Hole in the Solar Wind

Electron-scale magnetic holes filled with high-energy electrons can provide a seed population of electrons in the magnetosphere and might play an important role in the interaction between the magnetosphere and solar wind. Theoretical studies have investigated their generation mechanisms based on the 1D or 2D geometry of the structure. However, the generation mechanism is still unclear. Here we report on the 3D geometry of the electron-scale magnetic hole in the solar wind based on the Magnetospheric Multiscale mission. We find that the cross section of the magnetic hole with a size of ∼0.2-0.6 ρi (ion gyroradius) is either circular or 2D sheet-like. Electron vortices exist in both kinds of cross sections. The ellipse is a possible candidate for the geometry of the magnetic hole in the plane including its axis. Surprisingly, such an elliptical geometry suggests that the axial lengths of all our selected magnetic holes are ∼1-2 ρi. This 3D geometry might shed some light on the generation mechanism and role of the electron-scale magnetic hole in the astrophysical plasma.

Keywords: solar wind; planetary magnetospheres
Jovian Electrons in the Inner Heliosphere: Opportunities for Multi-spacecraft Observations and Modeling

In this paper we explore the idea of using multi-spacecraft observations of Jovian electrons to measure the 3D distribution of these particles in the inner heliosphere. We present simulations of Jovian electron intensities along selected spacecraft trajectories for 2021 and compare these, admittedly qualitatively, to these measurements. Using the data-model comparison we emphasize how such a study can be used to constrain the transport parameters in the inner heliosphere, and how this can lead to additional insight into energetic particle transport. Model results are also shown along the expected trajectories of selected spacecraft, including the off-ecliptic phase of the Solar Orbiter mission from 2025 onward. Lastly, we revisit the use of historical data and discuss upcoming missions that may contribute to Jovian electron measurements.

Keywords: heliosphere; interplanetary turbulence; cosmic rays
The Atacama Cosmology Telescope: Cosmology from Cross-correlations of unWISE Galaxies and ACT DR6 CMB Lensing

We present tomographic measurements of structure growth using cross-correlations of Atacama Cosmology Telescope (ACT) DR6 and Planck cosmic microwave background (CMB) lensing maps with the unWISE Blue and Green galaxy samples, which span the redshift ranges 0.2 ≲ z ≲ 1.1 and 0.3 ≲ z ≲ 1.8, respectively. We improve on prior unWISE cross-correlations not just by making use of the new, high-precision ACT DR6 lensing maps, but also by including additional spectroscopic data for redshift calibration and by analyzing our measurements with a more flexible theoretical model. We determine the amplitude of matter fluctuations at low redshifts (z ≃ 0.2–1.6), finding ${S}_{8}\equiv {\sigma }_{8}{({{\rm{\Omega }}}_{m}/0.3)}^{0.5}=0.813\pm 0.021$ using the ACT cross-correlation alone and S 8 = 0.810 ± 0.015 with a combination of Planck and ACT cross-correlations; these measurements are fully consistent with the predictions from primary CMB measurements assuming standard structure growth. The addition of baryon acoustic oscillation data breaks the degeneracy between σ 8 and Ω m , allowing us to measure σ 8 = 0.813 ± 0.020 from the cross-correlation of unWISE with ACT and σ 8 = 0.813 ± 0.015 from the combination of cross-correlations with ACT and Planck. These results also agree with the expectations from primary CMB extrapolations in ΛCDM cosmology; the consistency of σ 8 derived from our two redshift samples at z ∼ 0.6 and 1.1 provides a further check of our cosmological model. Our results suggest that structure formation on linear scales is well described by ΛCDM even down to low redshifts z ≲ 1.

Keywords: observational cosmology; sigma8; cosmological parameters from large-scale structure; cosmic microwave background radiation; weak gravitational lensing; large-scale structure of the universe; cosmology; cosmological parameters
Arcminute MicroKelvin Imager observations at 15 GHz of the 2020 February Outburst of Cygnus X-3

Here we report observations of a recent giant radio flare from Cygnus X-3 in 2020 February, made with the Arcminute MicroKelvin Imager.

Keywords: high mass x-ray binary stars; galactic radio sources; radio continuum emission; variable radiation sources
High-altitude Spider-type Prominence above the Magnetic Null Point

Rather unique observations of a high-altitude spider-type prominence in 2023 February are presented. The prominence or corresponding filament on the disk was not visible all the time but could appear and disappear in the course of a particular day. However, it persisted during the whole half of a solar rotation, being observable from day to day starting from the east limb of the Sun to the west limb. We show that the prominence was located in sagged coronal field lines just above a coronal magnetic null point. The presence of the null point and magnetic dips above it is confirmed by calculations of the potential magnetic field. The mass of the prominence apparently was appearing due to the condensation of hot coronal plasma after several eruptions that occurred in an active-region complex where the prominence was located. The prominence material flowed down along widely spread large coronal loops as coronal rain and was sometimes swept away by subsequent eruptions.

Keywords: solar activity; solar filaments; solar prominences; solar coronal loops
HST/COS Observations of Quasar Outflows in the 500-1050 Å Rest Frame. III. Four Similar Outflows in 2MASS J1051+1247 with Enough Energy to Be Major Contributors to AGN Feedback

We detect four very energetic outflows in the Hubble Space Telescope/Cosmic Origins Spectrograph spectra of quasar 2MASS J1051+1247 with a combined kinetic luminosity (\dot{E}_{K}) of 1046 erg s-1. Remarkable similarities are seen in these outflows: velocity centroids between 4900 and 5700 km s-1, distances from the central source (R) of a few hundred parsecs that are all consistent within the errors, and an \dot{E}_{K} within a factor of two for all outflows. Hence, a common origin for the outflows is probable. Most of the outflowing mass resides in a very high-ionization phase evident by troughs from Ne VIII, Na IX, Mg X, and Si XII, which connect the physical conditions of these ultraviolet outflows to the X-ray warm absorber outflows seen in nearby Seyfert galaxies. Three of the outflows have two or three independent diagnostics for the electron number density, yielding consistent values for each outflow, which increase the robustness of the R determinations. Troughs from never-before-seen ionic transitions of Ar VI, O IV*, Ne VI*, and Ne V* are identified. With a combined \dot{E}_{K} that is 7.0-2.3+6.5% of the quasar's Eddington luminosity, these outflows are prime candidates to be major agents for various active galactic nuclei feedback effects.

Keywords: active galactic nuclei; quasars; active galaxies; agn host galaxies; broad-absorption line quasar; quasar absorption line spectroscopy
Turbulence in the Very Local Interstellar Medium (VLISM)

The Voyager 1 spacecraft has been observing interstellar magnetic turbulence since it crossed the heliopause in 2012. Burlaga et al. reported that the turbulence appears to be compressible close to the heliopause and becomes incompressible farther away. In this paper, we undertake a more detailed analysis of the magnetic fluctuations measured by Voyager 1 from 2013 to 2019. We apply the techniques of wavelet analysis and Hilbert spectral analysis. These methods reveal temporal or spatial variations of the fluctuations that are not easily apparent using standard Fourier techniques. Our results suggest that the compressible fluctuations are confined to a smaller region than previously thought.

Keywords: interplanetary turbulence; interstellar medium; interstellar magnetic fields
Production of 44Ti and Iron-group Nuclei in the Ejecta of 3D Neutrino-driven Supernovae

The radioactive isotopes 44Ti and 56Ni are important products of explosive nucleosynthesis, which play a key role in supernova (SN) diagnostics and have been detected in several nearby young SN remnants. However, most SN models based on nonrotating single stars predict yields of 44Ti that are much lower than the values inferred from observations. We present, for the first time, the nucleosynthesis yields from a self-consistent three-dimensional SN simulation of a ~19 M ⊙ progenitor star that reaches an explosion energy comparable to that of SN 1987A and that covers the evolution of the neutrino-driven explosion until more than 7 s after core bounce. We find a significant enhancement of the Ti/Fe yield compared to recent spherically symmetric (1D) models and demonstrate that the long-time evolution is crucial to understanding the efficient production of 44Ti due to the nonmonotonic temperature and density history of the ejected material. Additionally, we identify characteristic signatures of the nucleosynthesis in proton-rich ejecta, in particular high yields of 45Sc and 64Zn.

Keywords: core-collapse supernovae; supernova remnants; gamma-ray sources; explosive nucleosynthesis; nucleosynthesis
Magnetic Activity and Physical Parameters of Exoplanet Host Stars Based on LAMOST DR7, TESS, Kepler, and K2 Surveys

Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) low- and medium-resolution spectroscopic surveys are important for determination of the orbital parameters and chromospheric activity of extrasolar planet systems. We crossmatched the exoplanet catalog confirmed before 2021 March 11 with the LAMOST DR7 survey to study their properties. There are 1026 targets with exoplanets observed in the LAMOST DR7 low-resolution spectroscopic survey and 158 targets in the medium-resolution spectroscopic survey. We have calculated the equivalent width of the Hα line and determined their stellar activity. The Hα and flare intensities are almost constant for the Rossby number Ro ≤ 0.12 in the saturated regime and decrease with increasing Ro in the unsaturated regime. In addition, we searched the flare events of all stars with exoplanets in the Transiting Exoplanet Survey Satellite (TESS), Kepler, and K2 surveys. Among the 733 extrasolar planetary systems observed by TESS, we found 481 flares from 57 stars. For Kepler data, we obtained the light curve of 1699 stars and found 1886 flares from 417 stars. For K2 data, we obtained the light curves of 347 stars and found 467 flares from 89 stars. There were light curves of 361 objects with obvious eclipse observed from the TESS survey. We have fitted their light curves with a high signal-to-noise ratio using the JKTEBOP program, and we reobtained the orbital parameters, such as inclination, radius, and period. In the end, we made a judgment on the habitability of exoplanets of stars with flares.

Keywords: stellar chromospheres; stellar flares; exoplanet catalogs