adsabs/SciX_UAT_keywords huggingface dataset:
Numerical MHD Simulations of the 3D Morphology and Kinematics of the 2017 September 10 CME-driven Shock from the Sun to Earth

A global, three-dimensional (3D) numerical simulation model has been employed to study the 3D morphology and kinematics of the large shock driven by the 2017 September 10 coronal mass ejection (CME). Based on actual solar observations, which include the photospheric magnetic field and the CME's speed and source location, the simulation result is delicately tuned by matching with coronal polarized brightness observations and in situ solar-wind measurements at 1 au. The simulation reproduces well the shock's shape and position in coronagraphic images. The shock's physical parameters at 1 au are similar to those constrained from the observations, with the simulated transit time being nearly the same as the observed one. The simulation reveals that the shock around the backward direction keeps propagating away from the Sun, and despite its large extent, the shock cannot be seen as a spherical structure forming a 360° envelope around the Sun. Identified as a fast forward shock, the shock has a sharp velocity jump and a large density compression with a Mach number larger than one from the nose toward the lateral parts, consistent with a driven shock all across the front. Compared to the nose, the right flank of the shock has a weak compression ratio, but probably yields enhanced energetic particles for observers aligned with it. It follows that large CME-driven shocks have the potential to accelerate energetic particles over a wide longitudinal separation and are likely responsible for the production of these particles in the inner heliosphere.

Keywords: solar coronal mass ejection shocks; solar wind; magnetohydrodynamical simulations
OGLE-2019-BLG-1180Lb: Discovery of a Wide-orbit Jupiter-mass Planet around a Late-type Star

We report on the discovery and analysis of the planetary microlensing event OGLE-2019-BLG-1180 with a planet-to-star mass ratio q ~ 0.003. The event OGLE-2019-BLG-1180 has unambiguous cusp-passing and caustic-crossing anomalies, which were caused by a wide planetary caustic with s ≃ 2, where s is the star-planet separation in units of the angular Einstein radius θ E. Thanks to well-covered anomalies by the Korea Micorolensing Telescope Network (KMTNet), we measure both the angular Einstein radius and the microlens parallax in spite of a relatively short event timescale of t E = 28 days. However, because of a weak constraint on the parallax, we conduct a Bayesian analysis to estimate the physical lens parameters. We find that the lens system is a super-Jupiter-mass planet of ${M}_{{\rm{p}}}={1.75}_{-0.51}^{+0.53}\,{M}_{{\rm{J}}}$ orbiting a late-type star of ${M}_{{\rm{h}}}={0.55}_{-0.26}^{+0.27}\,{M}_{\odot }$ at a distance ${D}_{{\rm{L}}}={6.1}_{-1.3}^{+0.9}\,\mathrm{kpc}$ . The projected star-planet separation is ${a}_{\perp }={5.19}_{-1.23}^{+0.90}\,\mathrm{au}$ , which means that the planet orbits at about four times the snow line of the host star. Considering the relative lens-source proper motion of μ rel = 6 mas yr-1, the lens will be separated from the source by 60 mas in 2029. At that time one can measure the lens flux from adaptive optics imaging of Keck or a next-generation 30 m class telescope. OGLE-2019-BLG-1180Lb represents a growing population of wide-orbit planets detected by KMTNet, so we also present a general investigation into prospects for further expanding the sample of such planets.

Keywords: exoplanet detection methods; gravitational microlensing; gravitational microlensing exoplanet detection
Optical Variability of Eight FRII-type Quasars with 13 yr Photometric Light Curves

We characterize the optical variability properties of eight lobe-dominated radio quasars (QSOs): B2 0709+37, FBQS J095206.3+235245, PG 1004+130, [HB89] 1156+631, [HB89] 1425+267, [HB89] 1503+691, [HB89] 1721+343, and 4C +74.26, systematically monitored for a duration of 13 yr since 2009. The quasars are radio-loud objects with extended radio lobes that indicate their orientation close to the sky plane. Five of the eight QSOs are classified as giant radio quasars. All quasars showed variability during our monitoring, with magnitude variations between 0.3 and 1 mag for the least variable and the most variable QSOs, respectively. We performed both structure function (SF) analysis and power spectral density (PSD) analysis for the variability characterization and search for characteristic timescales and periodicities. As a result of our analysis, we obtained relatively steep SF slopes (α ranging from 0.49 to 0.75) that are consistent with the derived PSD slopes (~2-3). All the PSDs show a good fit to single power-law forms, indicating a red-noise character of variability between timescales of ~13 yr and weeks. We did not measure reliable characteristic timescales of variability from the SF analysis, which indicates that the duration of the gathered data is too short to reveal them. The absence of bends in the PSDs (change of slope from ≥1 to ~0) on longer timescales indicates that optical variations are most likely caused by thermal instabilities in the accretion disk.

Keywords: quasars; galaxy photometry; active galaxies; radio loud quasars
Resolving Structure in the Debris Disk around HD 206893 with ALMA

Debris disks are tenuous, dusty belts surrounding main-sequence stars generated by collisions between planetesimals. HD 206893 is one of only two stars known to host a directly imaged brown dwarf orbiting interior to its debris ring, in this case at a projected separation of 10.4 au. Here we resolve structure in the debris disk around HD 206893 at an angular resolution of 0"6 (24 au) and wavelength of 1.3 mm with the Atacama Large Millimeter/submillimeter Array (ALMA). We observe a broad disk extending from a radius of <51 au to ${194}_{-2}^{+13}$ au. We model the disk with a continuous, gapped, and double power-law model of the surface density profile and find strong evidence for a local minimum in the surface density distribution near a radius of 70 au, consistent with a gap in the disk with an inner radius of ${63}_{-16}^{+8}$ au and width ${31}_{-7}^{+11}$ au. Gapped structure has been observed in four other debris disks-essentially every other radially resolved debris disk observed with sufficient angular resolution and sensitivity with ALMA-and could be suggestive of the presence of an additional planetary-mass companion.

Keywords: debris disks; submillimeter astronomy; exoplanet dynamics; brown dwarfs; interferometry
SPYGLASS. II. The Multigenerational and Multiorigin Star Formation History of Cepheus Far North

Young stellar populations provide a record of past star formation, and by establishing their members' dynamics and ages, it is possible to reconstruct the full history of star formation events. Gaia has greatly expanded the number of accessible stellar populations, with one of the most notable recently discovered associations being Cepheus Far North (CFN), a population containing hundreds of members spanning over 100 pc. With its proximity (d ≲ 200 pc), apparent substructure, and relatively small population, CFN represents a manageable population to study in depth, with enough evidence of internal complexity to produce a compelling star formation story. Using Gaia astrometry and photometry combined with additional spectroscopic observations, we identify over 500 candidate CFN members spread across seven subgroups. Combining ages from isochrones, asteroseismology, dynamics, and lithium depletion, we produce well-constrained ages for all seven subgroups, revealing a largely continuous 10 Myr star formation history in the association. By tracing back the present-day populations to the time of their formation, we identify two spatially and dynamically distinct nodes in which stars form, one associated with β Cephei, which shows mostly co-spatial formation, and one associated with EE Draconis with a more dispersed star formation history. This detailed view of star formation demonstrates the complexity of the star formation process, even in the smallest of regions.

Keywords: stellar associations; stellar ages; star formation; pre-main sequence stars
Effects of Partial Ionization on Magnetic Flux Emergence in the Sun

We have performed 3D numerical simulations to investigate the effect of partial ionization on the process of magnetic flux emergence. In our study, we have modified the single-fluid MHD equations to include the presence of neutrals and have performed two basic experiments: one that assumes a fully ionized plasma (FI case) and one that assumes a partially ionized plasma (PI case). We find that the PI case brings less dense plasma to and above the solar surface. Furthermore, we find that partial ionization alters the emerging magnetic field structure, leading to a different shape of the polarities in the emerged bipolar regions compared to the FI case. The amount of emerging flux into the solar atmosphere is larger in the PI case, which has the same initial plasma beta as the FI case, but a larger initial magnetic field strength. The expansion of the field above the photosphere occurs relatively earlier in the PI case, and we confirm that the inclusion of partial ionization reduces cooling due to adiabatic expansion. However, it does not appear to work as a heating mechanism for the atmospheric plasma. The performance of these experiments in three dimensions shows that PI does not prevent the formation of unstable magnetic structures, which erupt into the outer solar atmosphere.

Keywords: solar magnetic flux emergence; solar magnetic fields
Integrating Light Curve and Atmospheric Modeling of Transiting Exoplanets

Spectral retrieval techniques are currently our best tool to interpret the observed exoplanet atmospheric data. Said techniques retrieve the optimal atmospheric components and parameters by identifying the best fit to an observed transmission/emission spectrum. Over the past decade, our understanding of remote worlds in our galaxy has flourished thanks to the use of increasingly sophisticated spectral retrieval techniques and the collective effort of the community working on exoplanet atmospheric models. A new generation of instruments in space and from the ground is expected to deliver higher quality data in the next decade; it is therefore paramount to upgrade current models and improve their reliability, their completeness, and the numerical speed with which they can be run. In this paper, we address the issue of reliability of the results provided by retrieval models in the presence of systematics of unknown origin. More specifically, we demonstrate that if we fit directly individual light curves at different wavelengths (L-retrieval), instead of fitting transit or eclipse depths, as it is currently done (S-retrieval), the said methodology is more sensitive against astrophysical and instrumental noise. This new approach is tested, in particular, when discrepant simulated observations from Hubble Space Telescope/Wide Field Camera 3 and Spitzer/IRAC are combined. We find that while S-retrievals converge to an incorrect solution without any warning, L-retrievals are able to flag potential discrepancies between the data sets.

Keywords: astronomy data modeling; astronomy data analysis; exoplanet atmospheres; bayesian statistics; transit instruments
The JCMT BISTRO-2 Survey: The Magnetic Field in the Center of the Rosette Molecular Cloud

We present the first 850 μm polarization observations in the most active star-forming site of the Rosette Molecular Cloud (d ∼ 1.6 kpc) in the wall of the Rosette Nebula, imaged with the SCUBA-2/POL-2 instruments of the James Clerk Maxwell telescope, as part of the B-Fields In Star-forming Region Observations 2 (BISTRO-2) survey. From the POL-2 data we find that the polarization fraction decreases with the 850 μm continuum intensity with α = 0.49 ± 0.08 in the p ∝ I-α relation, which suggests that some fraction of the dust grains remain aligned at high densities. The north of our 850 μm image reveals a "gemstone ring" morphology, which is a ∼1 pc diameter ring-like structure with extended emission in the "head" to the southwest. We hypothesize that it might have been blown by feedback in its interior, while the B-field is parallel to its circumference in most places. In the south of our SCUBA-2 field the clumps are apparently connected with filaments that follow infrared dark clouds. Here, the POL-2 magnetic field orientations appear bimodal with respect to the large-scale Planck field. The mass of our effective mapped area is ∼174 M⊙, which we calculate from 850 μm flux densities. We compare our results with masses from large-scale emission-subtracted Herschel 250 μm data and find agreement within 30%. We estimate the plane-of-sky B-field strength in one typical subregion using the Davis-Chandrasekhar-Fermi technique and find 80 ± 30 μG toward a clump and its outskirts. The estimated mass-to-flux ratio of λ = 2.3 ± 1.0 suggests that the B-field is not sufficiently strong to prevent gravitational collapse in this subregion.

Keywords: interstellar magnetic fields; polarimetry; submillimeter astronomy; interstellar dust processes
Physical Conditions and Kinematics of the Filamentary Structure in Orion Molecular Cloud 1

We have studied the structure and kinematics of the dense molecular gas in the Orion Molecular Cloud 1 (OMC1) region with the N2H+ 3-2 line. The 6' × 9' (∼0.7 × 1.1 pc) region surrounding the Orion Kleinmann-Low (KL) core has been mapped with the Submillimeter Array (SMA) and the Submillimeter Telescope (SMT). The combined SMA and SMT image, with a resolution of ∼5"4 (∼2300 au), reveals multiple filaments with a typical width of 0.02-0.03 pc. On the basis of the non-local thermodynamic equilibrium analysis using the N2H+ 3-2 and 1-0 data, the density and temperature of the filaments are estimated to be ∼107 cm-3 and ∼15 K-20 K, respectively. The core fragmentation is observed in three massive filaments, one of which shows the oscillations in the velocity and intensity that could be the signature of core-forming gas motions. The gas kinetic temperature is significantly enhanced in the eastern part of OMC1, likely due to the external heating from the high-mass stars in M42 and M43. In addition, the filaments are colder than their surrounding regions, suggesting shielding from the external heating due to the dense gas in the filaments. The OMC1 region consists of three subregions, I.e., north, west, and south of Orion KL, having different radial velocities with sharp velocity transitions. There is a north-to-south velocity gradient from the western to the southern regions. The observed velocity pattern suggests that dense gas in OMC1 is collapsing globally toward the high-mass star-forming region, Orion Nebula Cluster.

Keywords: molecular clouds; interstellar filaments; star formation
Excited Hydroxyl Outflow in the High-mass Star-forming Region G34.26 + 0.15

G34.26 + 0.15 is a region of high-mass star formation that contains a broad range of young stellar objects in different stages of evolution, including a hot molecular core, hypercompact H II regions, and a prototypical cometary ultracompact H II region. Previous high-sensitivity single-dish observations by our group resulted in the detection of broad 6035 MHz OH absorption in this region; the line showed a significant blueshifted asymmetry indicative of molecular gas expansion. We present high-sensitivity Karl G. Jansky Very Large Array (VLA) observations of the 6035 MHz OH line conducted to image the absorption and investigate its origin with respect to the different star formation sites in the region. In addition, we report detection of 6030 MHz OH absorption with the VLA and further observations of 4.7 GHz and 6.0 GHz OH lines obtained with the Arecibo Telescope. The 6030 MHz OH line shows a very similar absorption profile as the 6035 MHz OH line. We found that the 6035 MHz OH line absorption region is spatially unresolved at ~2″ scales, and it is coincident with one of the bright ionized cores of the cometary H II region that shows broad radio recombination line emission. We discuss a scenario where the OH absorption is tracing the remnants of a pole-on molecular outflow that is being ionized inside-out by the ultracompact H II region.

Keywords: h ii regions; interstellar medium
Magnetic and Rotational Evolution of ρ CrB from Asteroseismology with TESS

During the first half of main-sequence lifetimes, the evolution of rotation and magnetic activity in solar-type stars appears to be strongly coupled. Recent observations suggest that rotation rates evolve much more slowly beyond middle age, while stellar activity continues to decline. We aim to characterize this midlife transition by combining archival stellar activity data from the Mount Wilson Observatory with asteroseismology from the Transiting Exoplanet Survey Satellite (TESS). For two stars on opposite sides of the transition (88 Leo and ρ CrB), we independently assess the mean activity levels and rotation periods previously reported in the literature. For the less active star (ρ CrB), we detect solar-like oscillations from TESS photometry, and we obtain precise stellar properties from asteroseismic modeling. We derive updated X-ray luminosities for both stars to estimate their mass-loss rates, and we use previously published constraints on magnetic morphology to model the evolutionary change in magnetic braking torque. We then attempt to match the observations with rotational evolution models, assuming either standard spin-down or weakened magnetic braking. We conclude that the asteroseismic age of ρ CrB is consistent with the expected evolution of its mean activity level and that weakened braking models can more readily explain its relatively fast rotation rate. Future spectropolarimetric observations across a range of spectral types promise to further characterize the shift in magnetic morphology that apparently drives this midlife transition in solar-type stars.

Keywords: stellar activity; stellar evolution; stellar oscillations; stellar rotation; stellar winds
Direct Collapse to Precursors of Supermassive Black Hole Seeds: Radiation-feedback-generated Outflows

We use high-resolution zoom-in cosmological simulations to model outflow triggered by radiation and thermal drivers around the central mass accumulation during direct collapse within the dark matter (DM) halo. The maximal resolution is 1.3 × 10-5 pc, and no restrictions are put on the geometry of the inflow/outflow. The central mass is considered prior to the formation of the supermassive black hole seed at a redshift of z ~ 15.9 and can constitute either a supermassive star (SMS) of ~105 M ⊙ surrounded by a growing accretion disk or a self-gravitating disk. The radiation transfer is modeled using the ray-tracing algorithm. Due to the high accretion rate of ~1 M ⊙ yr-1 determined by the DM halo, accretion is mildly supercritical, resulting in mildly supercritical luminosity that has only a limited effect on the accretion rate, with a duty cycle of ~0.9. We observe a fast development of hot cavities, which quickly extend into polar funnels and expand dense shells. Within the funnels, fast winds, ~103 km s-1, are mass-loaded by the accreting gas. We follow the expanding shells to ~1 pc, when the shell velocity remains substantially (~5 times) above the escape speed. The ionization cones formed by the central UV/X-ray completely ionize the cavities. Extrapolating the outflow properties shows that the halo material outside the shell will have difficulty stopping it. We therefore conclude that the expanding wind-driven shell will break out of the central parsec and will reach the halo virial radius. Finally, the anisotropic accretion flow on subparsec scales will attenuate the UV/soft X-rays on the H2. Hence, the formation of funnels and powerful outflows around, e.g., SMSs can have interesting observational corollaries.

Keywords: galaxies; active galactic nuclei; quasars; supermassive black holes; plasma astrophysics; early universe; high energy astrophysics; radiative transfer
The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. I. Detection of a Rich Population of Dusty Objects in the IRS 13 Cluster

A detailed analysis of the nuclear star cluster not only concedes the existence of the S cluster, with its fast-moving stars and the supermassive black hole Sgr A*. It also reveals an embedded region of gas and dust with an exceptionally high stellar density called IRS 13. The IRS 13 cluster can be divided into the northern and eastern counterparts, called IRS 13N and IRS 13E, respectively. This work will focus on both regions and study their most prominent members using rich infrared and radio/submillimeter data baselines. Applying a multiwavelength analysis enables us to determine a comprehensive photometric footprint of the investigated cluster sample. Using the ray-tracing-based radiative transfer model HYPERION, the spectral energy distribution of the IRS 13 members suggests a stellar nature of the dusty sources. These putative young stellar objects (YSOs) have a comparable spectroscopic identification to the D and G sources in or near the S cluster. Furthermore, we report the existence of a population of dusty sources in IRS 13 that can be mostly identified in the H, K, and L band. We propose that, together with the objects reported in the literature, this population is the outcome of a recent star formation process. Furthermore, we report that these presumably young objects are arranged in a disk structure. Although it cannot be excluded that the intrinsic arrangement of IRS 13 does show a disk structure, we find indications that the investigated cluster sample might be related to the counterclockwise disk.

Keywords: supermassive black holes; galactic center; young stellar objects; young massive clusters; intermediate-mass black holes
Velocity Dispersion of the GD-1 Stellar Stream

Tidally dissolved globular clusters form thin stellar streams that preserve a historical record of their past evolution. We report a radial velocity dispersion of 2.1 ± 0.3 km s-1 in the GD-1 stellar stream using a sample of 43 spectroscopically confirmed members. The GD-1 velocity dispersion is constant over the surveyed ≈15° span of the stream. We also measured velocity dispersion in the spur adjacent to the main GD-1 stream, and found a similar value at the tip of the spur. Surprisingly, the region of the spur closer to the stream appears dynamically colder than the main stream. An unperturbed model of the GD-1 stream has a velocity dispersion of ≈0.5 km s-1, indicating that GD-1 has undergone dynamical heating. Stellar streams arising from globular clusters, which prior to their arrival in the Milky Way, orbited a dwarf galaxy with a cored density profile are expected to have experienced the amount of heating required to match the velocity dispersion observed in GD-1. This suggests that GD-1 has been accreted and that imprints of its original host galaxy, including the inner slope of its dark matter halo, remain observable in the stream today.

Keywords: galaxy dynamics; stellar dynamics; milky way dynamics; cold dark matter