Sazuna/UAT_keywords huggingface dataset:
Evolution of Coronal Mass Ejection Properties in the Inner Heliosphere: Prediction for the Solar Orbiter and Parker Solar Probe. The evolution of the magnetic field and plasma quantities inside a coronal mass ejection (CME) with distance are known from statistical studies using data from 1 au monitors, planetary missions, Helios, and Ulysses. This does not cover the innermost heliosphere, below 0.29 au, where no data are yet publicly available. Here, we describe the evolution of the properties of simulated CMEs in the inner heliosphere using two different initiation mechanisms. We compare the radial evolution of these properties with that found from statistical studies based on observations in the inner heliosphere by Helios and MESSENGER. We find that the evolution of the radial size and magnetic field strength is nearly indistinguishable for twisted flux rope from that of writhed CMEs. The evolution of these properties is also consistent with past studies, primarily with recent statistical studies using in situ measurements and with studies using remote observations of CMEs.

Keywords: Interplanetary magnetic fields, Ejecta, Interplanetary physics, Solar coronal mass ejections
The Magnetic Flux Rope Structure of a Triangulated Solar Filament. Solar magnetic flux ropes are core structures driving solar activities. We construct a magnetic flux rope for a filament/prominence observed at 01:11 UT on 2011 June 21 in AR 11236 with a combination of state-of-the-art methods, including triangulation from multiperspective observations, the flux rope embedding method, the regularized Biot-Savart laws, and the magnetofrictional method. First, the path of the filament is reconstructed via the triangulation with 304 Å images observed by the Atmospheric Imaging Assembly on board Solar Dynamics Observatory (SDO) and by the Extreme Ultraviolet Imager on board the twin Solar Terrestrial Relations Observatory. Then, a flux rope is constructed with the regularized Biot-Savart laws using the information of its axis. Next, it is embedded into a potential magnetic field computed from the photospheric radial magnetic field observed by the Helioseismic and Magnetic Imager on board SDO. The combined magnetic field is finally relaxed by the magnetofrictional method to reach a nonlinear force-free state. It is found that both models constructed by the regularized Biot-Savart laws and after the magnetofrictional relaxation coincide with the 304 Å images. The distribution of magnetic dips coincides with part of the filament/prominence material, and the quasi-separatrix layers wrap the magnetic flux ropes, displaying hyperbolic flux tube structures. These models have the advantages of constructing magnetic flux ropes in the higher atmosphere and weak magnetic field regions, which could be used as initial conditions for magnetohydrodynamic simulations of coronal mass ejections.

Keywords: Solar photosphere, Solar prominences, Solar filaments, Solar corona, Solar magnetic fields, Solar activity
Energy Budgets for Terrestrial Extrasolar Planets. The pathways through which incoming energy is distributed between the surface and atmosphere have been analyzed for the Earth. However, the effect of the spectral energy distribution of a host star on the energy budget of an orbiting planet may be significant given the wavelength-dependent absorption properties of atmospheric CO2, water vapor, surface ice, and snow. We have quantified the flow of energy on aqua planets orbiting M-, G-, and F-dwarf stars, using a 3D Global Climate Model with a static ocean. The atmosphere and surface of an M-dwarf planet receiving an instellation equal to 88% of the modern solar constant at the top of the atmosphere absorb 12% more incoming stellar radiation than those of a G-dwarf planet receiving 100% of the modern solar constant, and 17% more radiation than an F-dwarf planet receiving 108% of the modern solar constant, resulting in climates similar to that of modern-day Earth on all three planets, assuming a 24 hr rotation period and fixed CO2. At 100% instellation, a synchronously rotating M-dwarf planet exhibits smaller flux absorption in the atmosphere and on the surface of the dayside, and a dayside mean surface temperature that is 37 K colder than its rapidly rotating counterpart. Energy budget diagrams are included to illustrate the variations in global energy budgets as a function of host star spectral class, and can contribute to habitability assessments of planets as they are discovered.

Keywords: Exoplanet atmospheric composition , Exoplanets, Exoplanet surface composition, Astrobiology, Interdisciplinary astronomy, Habitable planets
A Wind-disk Self-irradiation Model for Supercritical Accretion. Optical emission from actively accreting X-ray binaries is dominated by X-ray reprocessing on the outer disk. In the regime of supercritical accretion, strong radiation will power a massive wind that is optically thick and nearly spherical, and will occult the central hard X-rays from irradiating the outer disk. Instead, thermal emission from the wind will act as a new source of irradiation. Here, we construct a self-irradiation model in which the inner disk (within the wind photosphere) is completely blocked by the wind, the middle part (between the wind photosphere and scattersphere) is heated by the wind directly, and the outer disk (beyond the wind scattersphere) is heated by photons leaving the scattersphere. The model can adequately fit the UV/optical SED of NGC 247 X-1, a candidate source with supercritical accretion, while the standard irradiation model fails to produce a self-consistent result. The best-fit parameters suggest that the source contains a stellar-mass black hole with an accretion rate roughly 100 times the critical value. Remarkably, the UV/optical fitting predicts a wind photosphere that is consistent with X-ray measurements, although it is an extrapolation over three orders of magnitude in wavelength. This implies that supercritical accretion does power a massive wind and the UV/optical data are useful for constraining the wind structure.

Keywords: Accretion, X-ray binary stars, High energy astrophysics
Kelvin-Helmholtz Instability and Alfvénic Vortex Shedding in Solar Eruptions. We report on a three-dimensional MHD numerical experiment of a small-scale coronal mass ejection (CME)-like eruption propagating though a nonmagnetized solar atmosphere. We find that the Kelvin-Helmholtz instability (KHI) develops at various but specific locations at the boundary layer between the erupting field and the background atmosphere, depending on the relative angle between the velocity and magnetic field. KHI develops at the front and at two of the four sides of the eruption. KHI is suppressed at the other two sides of the eruption. We also find the development of Alfvénic vortex shedding flows at the wake of the developing CME due to the 3D geometry of the field. Forward modeling reveals that the observational detectability of the KHI in solar eruptions is confined to a narrow ≈10° range when observing off-limb, and therefore its occurrence could be underestimated due to projection effects. The new findings can have significant implications for observations, for heating, and for particle acceleration by turbulence from flow-driven instabilities associated with solar eruptions of all scales.

Keywords: Solar atmosphere, Magnetohydrodynamics, Solar magnetic flux emergence, Solar active regions, Solar corona, Solar coronal mass ejections, Solar magnetic fields, Solar activity, Solar atmospheric motions, Magnetohydrodynamical simulations
The DSHARP Rings: Evidence of Ongoing Planetesimal Formation?. Recent high-resolution interferometric observations of protoplanetary disks at (sub)millimeter wavelengths reveal omnipresent substructures, such as rings, spirals, and asymmetries. A detailed investigation of eight rings detected in five disks by the DSHARP survey came to the conclusion that all rings are just marginally optically thick with optical depths between 0.2 and 0.5 at a wavelength of 1.25 mm. This surprising result could either be coincidental or indicate that the optical depth in all of the rings is regulated by the same process. We investigated if ongoing planetesimal formation could explain the “fine-tuned” optical depths in the DSHARP rings by removing dust and transforming it into “invisible” planetesimals. We performed a one-dimensional simulation of dust evolution in the second dust ring of the protoplanetary disk around HD 163296, including radial transport of gas and dust, dust growth and fragmentation, and planetesimal formation via gravitational collapse of sufficiently dense pebble concentrations. We show that planetesimal formation can naturally explain the observed optical depths if streaming instability regulates the midplane dust-to-gas ratio to unity. Furthermore, our simple monodisperse analytical model supports the hypothesis that planetesimal formation in dust rings should universally limit their optical depth to the observed range.

Keywords: Gas-to-dust ratio, Planet formation, Dust continuum emission, Protoplanetary disks, Planetesimals, Circumstellar dust, Astronomical simulations
The Intrinsic Temperature and Radiative-Convective Boundary Depth in the Atmospheres of Hot Jupiters. In giant planet atmosphere modeling, the intrinsic temperature T int and radiative-convective boundary (RCB) are important lower boundary conditions. Often in one-dimensional radiative-convective models and in three-dimensional general circulation models it is assumed that T int is similar to that of Jupiter itself, around 100 K, which yields an RCB around 1 kbar for hot Jupiters. In this work, we show that the inflated radii, and hence high specific entropy interiors (8-11 k  b /baryon), of hot Jupiters suggest much higher T int. Assuming the effect is primarily due to current heating (rather than delayed cooling), we derive an equilibrium relation between T eq and T int, showing that the latter can take values as high as 700 K. In response, the RCB moves upward in the atmosphere. Using one-dimensional radiative-convective atmosphere models, we find RCBs of only a few bars, rather than the kilobar typically supposed. This much shallower RCB has important implications for the atmospheric structure, vertical and horizontal circulation, interpretation of atmospheric spectra, and the effect of deep cold traps on cloud formation.

Keywords: Exoplanet structure, Exoplanet evolution, Extrasolar gaseous giant planets, Exoplanet atmospheres
A New Luminous Blue Variable in the Outskirts of the Andromeda Galaxy. The hot massive luminous blue variables (LBVs) represent an important evolutionary phase of massive stars. Here, we report the discovery of a new LBV—LAMOST J0037+4016 in the distant outskirt of the Andromeda galaxy. It is located in the southwestern corner (a possible faint spiral arm) of M31 with an unexpectedly large projection distance of ∼22 kpc from the center. The optical light curve shows a 1.2 mag variation in V band and its outburst and quiescence phases both last over several years. The observed spectra indicate an A-type supergiant at an epoch close to the outburst phase and a hot B-type supergiant with weak [Fe II] emission lines at an epoch of much dimmer brightness. The near-infrared color-color diagram further shows that it follows the distribution of Galactic and M31 LBVs rather than B[e] supergiants. All the existing data strongly show that LAMOST J0037+4016 is an LBV. By spectral energy distribution fitting, we find it has a luminosity (4.42 ± 1.64) × 105 L ☉ and an initial mass ∼30 M ☉, indicating its nature of a less luminosity class of LBV.

Keywords: Andromeda Galaxy, Luminous blue variable stars, A supergiant stars
Observed Local Dispersion Relations for Magnetoacoustic-gravity Waves in the Sun’s Atmosphere: Mapping the Acoustic Cutoff Frequency. We present the observed local dispersion relations for magnetoacoustic-gravity waves in the Sun’s atmosphere for different levels of magnetic field strength. We model these data with a theoretical local dispersion relation to produce spatial maps of the acoustic cutoff frequency in the Sun’s photosphere. These maps have implications for the mechanical heating of the Sun’s upper atmosphere, by magnetoacoustic-gravity waves, at different phases of the solar magnetic activity cycle.

Keywords: Solar oscillations, Solar atmosphere, Solar magnetic fields
Evidence of Nonluminous Matter in the Center of M62. Theoretical models suggest that intermediate-mass black holes (IMBHs) may form and reside in the centers of globular clusters. IMBHs are still elusive to observations, but the accelerations of pulsars may bring along a unique fingerprint of their presence. In this work, we focus on the pulsars in the globular cluster M62. Using the new distance of M62 obtained from Gaia observations, we find that the measured pulsars’ accelerations suggest a central excess of mass in the range [1200, 6000] M ⊙, corresponding to [0.2, 1]% of the current total mass of the cluster. Our analysis cannot unambiguously discriminate between an IMBH or a system of stellar mass dark remnants of comparable total mass.

Keywords: Globular star clusters, Intermediate-mass black holes, Millisecond pulsars
Torus Constraints in ANEPD-CXO245: A Compton-thick AGN with Double-peaked Narrow Lines. We report on the torus constraints of the Compton-thick active galactic nucleus (AGN) with double-peaked optical narrow-line region emission lines, ANEPD-CXO245, at z = 0.449 in the AKARI NEP Deep Field. The unique infrared data on this field, including those from the nine-band photometry over 2-24 μm with the AKARI Infrared Camera, and the X-ray spectrum from Chandra allow us to constrain torus parameters such as the torus optical depth, X-ray absorbing column, torus angular width (σ), and viewing angle (i). We analyze the X-ray spectrum as well as the UV-optical-infrared spectral energy distribution (UOI-SED) with clumpy torus models in X-ray (XCLUMPY) and infrared (CLUMPY), respectively. From our current data, the constraints on σ-i from both X-rays and UOI show that the line of sight crosses the torus as expected for a type 2 AGN. We obtain a small X-ray scattering fraction (&lt;0.1%), which suggests narrow torus openings, giving preference to the bipolar outflow picture of the double-peaked profile. Comparing the optical depth of the torus from the UOI-SED and the absorbing column density N H from the X-ray spectrum, we find that the gas-to-dust ratio is ≳4 times larger than the Galactic value.

Keywords: X-ray active galactic nuclei, Active galactic nuclei, Infrared galaxies, Spectroscopy, Infrared photometry
A Break in Spiral Galaxy Scaling Relations at the Upper Limit of Galaxy Mass. Super spirals are the most massive star-forming disk galaxies in the universe. We measured rotation curves for 23 massive spirals with the Southern African Large Telescope (SALT) and found a wide range of fast rotation speeds (240-570 km s-1), indicating enclosed dynamical masses of (0.6-4) × 1012 M ⊙. Super spirals with mass in stars {log}{M}stars}/{M}⊙ &gt; 11.5 break from the baryonic Tully-Fisher relation (BTFR) established for lower-mass galaxies. The BTFR power-law index breaks from 3.75 ± 0.11 to 0.25 ± 0.41 above a rotation speed of ∼340 km s-1. Super spirals also have very high specific angular momenta that break from the Fall relation. These results indicate that super spirals are undermassive for their dark matter halos, limited to a mass in stars of {log}{M}stars}/{M}⊙ &lt; 11.8. Most giant elliptical galaxies also obey this fundamental limit, which corresponds to a critical dark halo mass of {log}{M}halo}/{M}⊙ ≃ 12.7. Once a halo reaches this mass, its gas can no longer cool and collapse in a dynamical time. Super spirals survive today in halos as massive as {log}{M}halo}/{M}⊙ ≃ 13.6, continuing to form stars from the cold baryons they captured before their halos reached critical mass. The observed high-mass break in the BTFR is inconsistent with the Modified Newtonian Dynamics theory.

Keywords: Galaxy evolution, Galaxy rotation curves, Dark matter, Spiral galaxies
Where Are the Electromagnetic-wave Counterparts of Stellar-mass Binary Black Hole Mergers?. Multimessenger astronomy, combining gravitational-wave (GW) and electromagnetic-wave (EM) observations, has a huge impact on physics, astrophysics, and cosmology. However, the majority of sources detected with currently running ground-based GW observatories are binary black hole (BBH) mergers, which disappointingly were expected to have no EM counterparts. In this Letter, we propose that if a BBH merger happens in a gaseous disk around a supermassive black hole, the merger can be accompanied by a transient radio flare like a fast radio burst (FRB). We argue that the total mass and the effective spin derived from GW detection can be used to distinguish such a source from other channels of BBH mergers. If this prediction is confirmed with future observations, multimessenger astronomy can be greatly improved. The mystery of the origin of FRBs could also be revealed partially.

Keywords: Gravitational waves, Astrophysical black holes, Radio transient sources
Coronal Response to Magnetically Suppressed CME Events in M-dwarf Stars. We report the results of the first state-of-the-art numerical simulations of coronal mass ejections (CMEs) taking place in realistic magnetic field configurations of moderately active M-dwarf stars. Our analysis indicates that a clear, novel, and observable, coronal response is generated due to the collapse of the eruption and its eventual release into the stellar wind. Escaping CME events, weakly suppressed by the large-scale field, induce a flare-like signature in the emission from coronal material at different temperatures due to compression and associated heating. Such flare-like profiles display a distinctive temporal evolution in their Doppler shift signal (from red to blue), as the eruption first collapses toward the star and then perturbs the ambient magnetized plasma on its way outwards. For stellar fields providing partial confinement, CME fragmentation takes place, leading to rise and fall flow patterns which resemble the solar coronal rain cycle. In strongly suppressed events, the response is better described as a gradual brightening, in which the failed CME is deposited in the form of a coronal rain cloud leading to a much slower rise in the ambient high-energy flux by relatively small factors (∼2-3). In all the considered cases (escaping/confined) a fractional decrease in the emission from midrange coronal temperature plasma occurs, similar to the coronal dimming events observed on the Sun. Detection of the observational signatures of these CME-induced features requires a sensitive next generation X-ray space telescope.

Keywords: Solar flares, Stellar coronal dimming, Stellar magnetic fields, Stellar mass loss, Stellar activity, Stellar winds, Stellar flares, Stellar coronal mass ejections, Magnetohydrodynamical simulations
Long-standing Small-scale Reconnection Processes at Saturn Revealed by Cassini. The internal mass source from the icy moon Enceladus in Saturn’s rapidly rotating magnetosphere drives electromagnetic dynamics in multiple spatial and temporal scales. The distribution and circulation of the internal plasma and associated energy are thus crucial in understanding Saturn’s magnetospheric environment. Magnetic reconnection is one of the key processes in driving plasma and energy transport in the magnetosphere, and also a fundamental plasma process in energizing charged particles. Recent works suggested that reconnection driven by Saturn’s rapid rotation might appear as a chain of microscale structures, named drizzle-like reconnection. The drizzle-like reconnection could exist not only in the nightside magnetodisk, but also in the dayside magnetodisk. Here, using in situ measurements from the Cassini spacecraft, we report multiple reconnection sites that were successively detected during a time interval longer than one rotation period. The time separation between two adjacently detected reconnection sites can be much less than one rotation period, implying that the reconnection processes are likely small-scale, or frequently repetitive. The spatial distribution of the identified long-standing multiple small reconnection site sequences shows no significant preference on local times. We propose that the small reconnection sites discussed in this Letter are rotationally driven and rotate with the magnetosphere. Since the reconnection process on Saturn can be long-durational, the rotational regime can cause these small-scale reconnection sites to spread to all local times, resulting in global release of energy and mass from the magnetosphere.

Keywords: Planetary magnetospheres, Interplanetary particle acceleration, Solar magnetic reconnection
New Candidate Planetary Nebulae in Galactic Globular Clusters from the VVV Survey. Only four globular cluster planetary nebulae (GCPN) are known so far in the Milky Way. About 50 new globular clusters have been recently discovered toward the Galactic bulge. We present a search for planetary nebulae within 3′ of the new globular clusters, revealing the identification of new candidate GCPN. These possible associations are PN SB 2 with the GC Minni 06, PN G354.9-02.8 with the GC Minni 11, PN G356.8-03.6 with the GC Minni 28, and PN Pe 2-11 with the GC Minni 31. We discard PN H 2-14 located well within the projected tidal radius of the new globular cluster FSR1758 because they have different measured radial velocities. These are interesting objects that need follow-up observations (especially radial velocities) in order to confirm membership and to measure their physical properties in detail. If confirmed, this would double the total number of Galactic GCPN. Based on observations taken within the ESO programmes 179.B-2002 and 298.D-5048.

Keywords: Globular star clusters, Planetary nebulae, Milky Way Galaxy, Galactic bulge
Searching for Hypermassive Neutron Stars with Short Gamma-Ray Bursts. Neutron star mergers can form a hypermassive neutron star (HMNS) remnant, which may be the engine of a short gamma-ray burst (SGRB) before it collapses to a black hole, possibly several hundred milliseconds after the merger. During the lifetime of an HMNS, numerical relativity simulations indicate that it will undergo strong oscillations and emit gravitational waves with frequencies of a few kilohertz, which are unfortunately too high for detection to be probable with the Advanced Laser Interferometer Gravitational-Wave Observatory. Here we discuss the current and future prospects for detecting these frequencies as modulation of the SGRB. The understanding of the physical mechanism responsible for the HMNS oscillations will provide information on the equation of state of the hot HMNS, and the observation of these frequencies in the SGRB data would give us insight into the emission mechanism of the SGRB.

Keywords: Neutron stars, Gamma-ray bursts, Gravitational waves, Stellar pulsations
Multi-TeV Flaring from High-energy Blazars: An Evidence of the Photohadronic Process. High-energy peaked blazars are known to undergo episodes of flaring in GeV-TeV gamma-rays involving different timescales. This flaring mechanism is not well understood, despite long-term simultaneous multiwavelength observations. These gamma-rays en route to Earth undergo attenuation by the extragalactic background light. Using the photohadronic model, where the seed photons follow a power-law spectrum and a template extragalactic background light model, we derive a simple relation between the observed multi-TeV gamma-ray flux and the intrinsic flux with a single parameter. We study 42 flaring epochs of 23 blazars and excellent fits to most of the observed spectra are obtained, strengthening the photohadronic origin of multi-TeV gamma-rays. We can also constrain the power spectrum of the seed photons during the flaring period. Stringent bounds on the blazars of unknown redshifts, whose multi-TeV flaring spectra are known, can be placed using the photohadronic model.

Keywords: BL Lacertae objects, High energy astrophysics, Blazars, Relativistic jets, Gamma-rays