adsabs/SciX_UAT_keywords huggingface dataset:
A New Comprehensive Data Set of Solar Filaments of 100 yr Interval. I.

Filaments are very common physical phenomena on the Sun and are often taken as important proxies of solar magnetic activities. The study of filaments has become a hot topic in the space weather research. For a more comprehensive understanding of filaments, especially for an understanding of solar activities of multiple solar cycles, it is necessary to perform a combined multifeature analysis by constructing a data set of multiple solar cycle data. To achieve this goal, we constructed a centennial data set that covers the Hα data from five observatories around the world. During the data set construction, we encountered varieties of problems, such as data fusion, accurate determination of the solar edge, classifying data by quality, dynamic threshold, and so on, which arose mainly due to multiple sources and a large time span of data. But fortunately, these problems were well solved. The data set includes seven types of data products and eight types of feature parameters with which we can implement the functions of data searching and statistical analyses. It has the characteristics of better continuity and highly complementary to space observation data, especially in the wavelengths not covered by space observations, and covers many solar cycles (including more than 60 yr of high-cadence data). We expect that this new comprehensive data set as well as the tools will help researchers to significantly speed up their search for features or events of interest, for either statistical or case study purposes, and possibly help them get a better and more comprehensive understanding of solar filament mechanisms.

Keywords: solar filaments; solar chromosphere; astronomy data analysis; astronomy databases; astronomy data visualization
The -12 mag Dip in the Galaxy Luminosity Function of Hickson Compact Groups

We present the galaxy luminosity functions (LFs) of four Hickson Compact Groups using image data from the Subaru Hyper Suprime-Cam. A distinct dip appeared in the faint ends of all the LFs at Mg ∼ -12. A similar dip was observed in the LFs of the galaxy clusters Coma and Centaurus. However, LFs in the Virgo, Hydra, and the field had flatter slopes and no dips. As the relative velocities among galaxies are lower in compact groups than in clusters, the effect of galaxy-galaxy interactions would be more significant in compact groups. The Mg ∼ -12 dip of compact groups may imply that frequent galaxy-galaxy interactions would affect the evolution of galaxies, and the dip in LF could become a boundary between different galaxy populations. * Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Keywords: hickson compact group; luminosity function; dwarf galaxies
The Nature of the Absorbed Soft X-Ray Variations in Compton-thin Type-II Active Galactic Nuclei

The absorbed soft X-ray (<1 keV) emission from Compton thin type-II active galactic nuclei (AGNs) with neutral absorption columns in the range NH = 1021-23 cm-2 may contain emission from star formation or scattered photons from the primary X-ray emission in Compton-thin circumnuclear gas extending out to ∼1 kpc, or leaky-absorbers along the line of sight allowing a part of the primary AGN emission to manifest in the soft X-rays. In a recent sample study of 20 Compton thin type-II AGN, Laha et al. detected variability in the soft X-ray spectra in 5 sources with timescales <20 years, indicating possibly that the primary AGN emission has leaked through the absorption column. I found that the sources with soft X-ray variability exhibit the lowest absorption column densities (NH ∼ 0.7-1.3 × 1022 cm-2) in the sample.

Keywords: active galactic nuclei
In Situ Evidence of a Magnetic Hole Downstream of the Magnetic Reconnection in the Magnetopause Reconnection

Recently, an electron-scale coherent structure known as a magnetic hole (MH) was observed in the Earth's magnetosheath. It has been found that the MH is characterized by decreasing magnetic field strength and increasing parameters such as electron density, temperature, and temperature anisotropy. Observations suggest that electron temperature anisotropy within an MH structure provides free energy to generate whistler waves. In this study, a small-scale MH formed in the downstream region of the magnetic reconnection, indicating that the region far away from the X-line may be another important electron heating channel. A strong energy-dissipating current layer is observed near the boundary within MH, implying that boundary may be the energy source for MH heating electrons. These characteristics indicate that the observed MH is still highly dynamic and has multiscale coupling processes.

Keywords: magnetic fields; space plasmas; plasma jets
The Next Generation Deep Extragalactic Exploratory Public (NGDEEP) Survey

We present the Next Generation Deep Extragalactic Exploratory Public (NGDEEP) Survey, a deep slitless spectroscopic and imaging Cycle 1 JWST treasury survey designed to constrain feedback mechanisms in low-mass galaxies across cosmic time. NGDEEP targets the Hubble Ultra Deep Field (HUDF) with NIRISS slitless spectroscopy ( ${f}_{\mathrm{lim},\mathrm{line},5\sigma }\approx 1.2\,\times \,$ 10‑18 erg s‑1 cm‑2) to measure metallicities and star formation rates (SFRs) for low-mass galaxies through the peak of the cosmic SFR density (0.5 < z < 4). In parallel, NGDEEP targets the HUDF-Par2 parallel field with NIRCam ( ${m}_{\mathrm{lim},5\sigma }=30.6-30.9$ ) to discover galaxies to z > 12, constraining the slope of the faint end of the rest-ultraviolet luminosity function. NGDEEP overlaps with the deepest HST Advanced Camera for Surveys optical imaging in the sky, F435W in the HUDF ( ${m}_{\mathrm{lim},{\rm{F}}435{\rm{W}}}=29.6$ ) and F814W in HUDF-Par2 ( ${m}_{\mathrm{lim},{\rm{F}}814{\rm{W}}}=30$ ), making this a premier HST+JWST deep field. As a treasury survey, NGDEEP data are public immediately, and we will rapidly release data products and catalogs in the spirit of previous deep-field initiatives. In this paper we present the NGDEEP survey design, summarize the science goals, and detail plans for the public release of NGDEEP reduced data products.

Keywords: early universe; galaxy formation; galaxy evolution; galaxy chemical evolution
In Situ Heating of the Nightside Martian Upper Atmosphere and Ionosphere: The Role of Solar Wind Electron Precipitation

In the absence of solar radiation, precipitating electrons from the solar wind (SW) are generally thought to be the dominant source of energy deposition in the nightside Martian upper atmosphere, creating a patchy ionosphere and possibly also affecting the nightside thermal budget of various neutral and ionized species. Previous model calculations have not taken into account in situ heating via SW electron impact. In the present study, we utilize extensive measurements made by several instruments on board the Mars Atmosphere and Volatile Evolution spacecraft, in order to perform data-driven computations of the nightside neutral, ion, and electron heating rates. Considering the large range of energetic electron intensity observed on the nightside of Mars, we divide the entire data set into two subsamples, either with or without energetic electron depletion, a notable feature of the nightside Martian ionosphere. Our calculations indicate that in situ nightside neutral heating is dominated by exothermic chemistry and Maxwell interaction with thermal ions for regions with depletion, and by direct SW impact for regions without. Collisional quenching of excited state species produced from a variety of channels, such as electron impact excitation, dissociation, and ionization, as well as ${{\rm{O}}}_{2}^{+}$ dissociative recombination, makes a substantial contribution to neutral heating, except during depletion. For comparison, nightside ion heating is mainly driven by energetic ion production under all circumstances, which occurs mainly via ion-neutral reaction O+ + CO2 and CO2+ predissociation.

Keywords: planetary atmospheres; mars
Evidence of a Tidal-disruption Event in GSN 069 from the Abnormal Carbon and Nitrogen Abundance Ratio

GSN 069 is an ultra-soft X-ray active galactic nucleus that previously exhibited a huge X-ray outburst and a subsequent long-term decay. It has recently presented X-ray quasi-periodic eruptions (QPEs). We report the detection of strong nitrogen lines but weak or undetectable carbon lines in its far-ultraviolet spectrum. With a detailed photoionization model, we use the C IV/N IV] ratio and other ratios between nitrogen lines to constrain the [C/N] abundance of GSN 069 to be from -3.33 to -1.91. We argue that a partially disrupted red giant star can naturally explain the abnormal C/N abundance in the UV spectrum, while the surviving core orbiting the black hole might produce the QPEs.

Keywords: active galactic nuclei; active galaxies
GRB 200826A: A Precursor of a Long Gamma-Ray Burst with Missing Main Emission

The recently discovered peculiar gamma-ray burst GRB 200826A poses a dilemma for the collapsar model. Although all other characteristics of the burst are consistent with it being a Type II (i.e., collapse of a massive star) event, the observed duration of the event is only approximately 1 s, which is at odds with the predicted allowable timescale range for a collapsar event. To resolve this dilemma, this Letter proposes that the original burst could be an intrinsically long GRB comprising a precursor and a main emission phase. However, the main emission phase is missed due to either precession of the jet or the obstruction by a companion star, leaving only the precursor observed as a short-duration GRB 200826A. Interestingly, we found that the temporal and spectral properties of GRB 200826A broadly resembled those of the bright precursor observed in GRB 160625B. Furthermore, assuming the prototype burst of GRB 200826A is similar to that of GRB 160625B, we found that the observer may indeed miss its main emission because of geometric effects caused either by jet precession or companion-obstruction models. Our approach provides a natural explanation for the GRB 200826A-like bursts and agrees with the rarity of those events.

Keywords: gamma-ray bursts
Detecting Isolated Stellar-mass Black Holes with the Roman Telescope

Isolated stellar-mass black holes (ISMBHs) are potentially discernible through microlensing observations, because they are expected to be long-duration microlensing events. In this work, we study the detection and characterization of ISMBHs using Roman observations. We simulate a large ensemble of such events, as they will be seen by Roman, and estimate the errors in the physical parameters of the lens objects, including their masses, distances, and proper motions, by calculating Fisher and covariance matrices. Since the ~2.3 yr time gap between Roman's first three observing seasons and its latter three seasons may lower the efficiency of its realization of microlensing events and characterization of ISMBHs, we additionally consider a scenario where we add a small number of additional observations-1 hr of observations, every 10 days, when the Bulge is observable during the large time gap-which is equivalent to a total of an additional day of observations with the Roman telescope. These extra observations increase Roman's efficiency in terms of characterizing ISMBHs by ~1%-2%, and, more importantly, they improve the robustness of the results, by avoiding possible degenerate solutions. By considering uniform and power-law mass functions ( ${dN}/{dM}\propto {M}^{-\alpha }$ , α = 2, 1, 0.5) for ISMBHs in the range of [2, 50]M ⊙, we conclude that the Roman telescope will determine the physical parameters of the lenses (the mass, distance, and relative lens-source angular velocity) within <5% uncertainty, with efficiencies of 21% and 16%-18%, respectively. By considering these mass functions, we expect that during its mission the Roman telescope will detect and characterize 3-4, 15-17, and 22-24 ISMBHs through astrometric microlensing, with the relative errors for all physical parameters being less than 1%, 5%, and 10%, respectively. Microlensing events due to ISMBHs with masses ≃10-25M ⊙ that are located close to the observer, with D l ≲ 0.5D s, while the source is inside the Galactic disk, can be characterized with the fewest errors.

Keywords: gravitational microlensing; stellar mass black holes; space telescopes; computational methods
Role of Planetary Radius on Atmospheric Escape of Rocky Exoplanets

Large-scale characterization of exoplanetary atmospheres is on the horizon, thereby making it possible in the future to extract their statistical properties. In this context, by using a well-validated model in the solar system, we carry out 3D magnetohydrodynamic simulations to compute nonthermal atmospheric ion escape rates of unmagnetized rocky exoplanets as a function of their radius based on fixed stellar radiation and wind conditions. We find that the atmospheric escape rate is, unexpectedly and strikingly, a nonmonotonic function of the planetary radius R and that it evinces a maximum at R ∼ 0.7 R ⊕. This novel nonmonotonic behavior may arise from an intricate trade-off between the cross-sectional area of a planet (which increases with size, boosting escape rates) and its associated escape velocity (which also increases with size but diminishes escape rates). Our results could guide forthcoming observations because worlds with certain values of R (such as R ∼ 0.7 R ⊕) might exhibit comparatively higher escape rates when all other factors are constant.

Keywords: astrobiology; magnetohydrodynamical simulations; habitable planets; exoplanet atmospheres; stellar winds
Absolute Calibration of Diffuse Radio Surveys at 45 and 150 MHz

We use measurements from the Experiment to Detect the Global EoR Signature (EDGES) to determine scale and zero-level corrections to the diffuse radio surveys by Guzmán et al. at 45 MHz and by Landecker & Wielebinski at 150 MHz. We find that the map of Guzmán et al. requires a scale correction of 1.076 ± 0.034 (2σ) and a zero-level correction of -160 ± 78 K (2σ) to best-fit the EDGES data. For the map of Landecker & Wielebinski, the scale correction is 1.112 ± 0.023 (2σ) and the zero-level correction is 0.7 ± 6.0 K (2σ). The correction uncertainties are dominated by systematic effects, of which the most significant are uncertainty in the calibration of the EDGES receivers, antenna pointing, and tropospheric and ionospheric effects. We propagate the correction uncertainties to estimate the uncertainties in the corrected maps themselves and find that the 2σ uncertainty in the map brightness temperature is in the range 3.2%-7.5% for the map of Guzmán et al. and 2.1%-9.0% for the map of Landecker & Wielebinski, with the largest percentage uncertainties occurring at high Galactic latitudes. The corrected maps could be used to improve existing diffuse low-frequency radio sky models, which are essential tools in analyses of cosmological 21 cm observations, as well as to investigate the existence of a radio monopole excess above the cosmic microwave background and known Galactic and extragalactic contributions.

Keywords: observational cosmology; brightness temperature; astronomical instrumentation
Origin of Galactic Sub-PeV Diffuse Gamma-Ray Emission: Constraints from High-energy Neutrino Observations

Very recently, diffuse gamma-rays with 0.1 PeV < Eγ < 1 PeV have been discovered from the Galactic disk by the Tibet air shower array and muon detector array (Tibet AS+MD array). While the measured sub-PeV flux may be compatible with the hadronic origin in the conventional Galactic cosmic-ray propagation model, we find that it is in possible tension with the nondetection of Galactic neutrino emissions by the IceCube neutrino telescope. We further find that the presence of an extra cosmic-ray component of relatively hard spectrum, which is probably related to the Cygnus Cocoon region and other PeV cosmic-ray sources in the Galactic disk, would alleviate the tension. This scenario implies the existence of an extreme accelerator of either protons or electrons beyond PeV in the Cygnus region, and predicts the continuation of the gamma-ray spectrum of Cygnus Cocoon up to 1 PeV with a possible hardening beyond ∼30-100 TeV.

Keywords: galactic cosmic rays; gamma-ray sources; diffuse radiation
Pickup Ion-Mediated Magnetic Reconnection in the Outer Heliosphere

Pickup ions (PUIs) play a crucial role in the heliosphere, contributing to the mediation of large-scale structures such as the distant solar wind, the heliospheric termination shock, and the heliopause. While magnetic reconnection is thought to be a common process in the heliosphere due to the presence of heliospheric current sheets, it is poorly understood how PUIs might affect the evolution of magnetic reconnection. Although it is reasonable to suppose that PUIs decrease the reconnection rate since the plasma beta becomes much larger than 1 when PUIs are included, we show for the first time that such a supposition is invalid and that PUI-induced turbulence, heat conduction, and viscosity can preferentially boost magnetic reconnection in heliospheric current sheets in the distant solar wind. This suggests that it is critical to include the effect of the turbulence, heat conduction, and viscosity caused by PUIs to understand the dynamics of magnetic reconnection in the outer heliosphere.

Keywords: heliosphere; solar magnetic reconnection; pickup ions
Mapping out the Stellar Populations of IC 2602 and IC 2391

IC 2391 and IC 2602 are important benchmarks for testing early star and planet evolution theories, both structural and dynamical, because they are the nearest open clusters with ages of ~50 Myr. We refine membership lists for these clusters by identifying candidate members using Gaia DR2 kinematic and distance information. We identify 451 candidate members of IC 2602 and 350 candidate members of IC 2391. If confirmed, this would increase the known populations of these clusters by 275% and 130%, respectively. We use CHIRON on the CTIO/SMARTS 1.5 m telescope via fiber mode which yields a resolution of 27,400 to acquire high-resolution spectra of 26 new candidate cluster members brighter than G = 13 magnitude, as well as an additional 12 previously known members. Measures of lithium, Hα, stellar properties (T eff, log(g), [Fe/H]), radial velocities, and $v\sin i$ values from these spectra are used to confirm cluster membership. We find that 37 of 38 stars we observe are bona fide cluster members, of which four are new candidate photometric binaries and 10 are new candidate spectroscopic binaries.

Keywords: open star clusters; young star clusters
Topography of the Young Galactic Disk: Spatial and Kinematic Patterns of Clustered Star Formation in the Solar Neighborhood

The accuracy in determining the spatial-kinematical parameters of open clusters makes them ideal tracers of the Galactic structure. Young open clusters (YOCs) are the main representatives of the clustered star formation mode, which identifies how most of the stars in the Galaxy form. We apply the Kriging technique to a sample of Gaia YOCs within a 3.5 kpc radius around the Sun and log(age) ≤ 7.5, as the age in years, to obtain Z(X, Y) and V Z (X, Y) maps. Previous work by Alfaro et al. has shown that Kriging can provide reliable results even with small data samples (N ~ 100). We approach the 3D spatial and vertical velocity field structure of the Galactic disk defined by YOCs and analyze the hierarchy of the stellar cluster formation, which shows a rich hierarchical structure, displaying complexes embedded within each other. We discuss the fundamental characteristics of the methodology used to perform the mapping and point out the main results obtained in phenomenological terms. Both the 3D spatial distribution and the vertical velocity field reveal a complex disk structure with a high degree of substructures. Their analysis provides clues about the main physical mechanisms that shape the phase space of the clustered star formation in this Galactic area. Warp, corrugations, and high local deviations in Z and V Z appear to be intimately connected, in a single but intricate scenario.

Keywords: open star clusters; star formation; catalogs; surveys; milky way disk; milky way dynamics
Doppler Beaming of M Dwarfs in TESS, Kepler/K2, and Gaia Photometry

The Doppler beaming amplitude of a M dwarf is amplified relative to a blackbody of the same temperature because of deep TiO absorption features in M dwarf spectra. A strong Na feature at 5890 Å coincides with the short wavelength cutoff of the Transiting Exoplanet Survey Satellite response function, which also increases the beaming amplitude. As a result, the Doppler beaming effect for a 3000 K object is a factor of 1.4-2.0 times greater than predicted for a blackbody. Underestimating the Doppler beaming coefficient could result in mass overestimates when using the photometric beaming amplitude to determine stellar properties. This is especially important for M dwarfs in short period binary systems with massive white dwarf, neutron star or black hole companions.

Keywords: doppler shift; white dwarf stars; m dwarf stars; photometry; binary stars
SN 2022oqm–A Ca-rich Explosion of a Compact Progenitor Embedded in C/O Circumstellar Material

We present the discovery and analysis of SN 2022oqm, a Type Ic supernova (SN) detected <1 day after the explosion. The SN rises to a blue and short-lived (2 days) initial peak. Early-time spectral observations of SN 2022oqm show a hot (40,000 K) continuum with high ionization C and O absorption features at velocities of 4000 km s‑1, while its photospheric radius expands at 20,000 km s‑1, indicating a pre-existing distribution of expanding C/O material. After ∼2.5 days, both the spectrum and light curves evolve into those of a typical SN Ic, with line velocities of ∼10,000 km s‑1, in agreement with the evolution of the photospheric radius. The optical light curves reach a second peak at t ≈ 15 days. By t = 60 days, the spectrum of SN 2022oqm becomes nearly nebular, displaying strong Ca II and [Ca II] emission with no detectable [O I], marking this event as Ca-rich. The early behavior can be explained by 10‑3 M ⊙ of optically thin circumstellar material (CSM) surrounding either (1) a massive compact progenitor such as a Wolf–Rayet star, (2) a massive stripped progenitor with an extended envelope, or (3) a binary system with a white dwarf. We propose that the early-time light curve is powered by both the interaction of the ejecta with the optically thin CSM and shock cooling (in the massive star scenario). The observations can be explained by CSM that is optically thick to X-ray photons, is optically thick in the lines as seen in the spectra, and is optically thin to visible-light continuum photons that come either from downscattered X-rays or from the shock-heated ejecta. Calculations show that this scenario is self-consistent.

Keywords: type ic supernovae; core-collapse supernovae; circumstellar matter; ultraviolet astronomy