adsabs/SciX_UAT_keywords huggingface dataset:
Updated Radiative Transfer Model for Titan in the Near-infrared Wavelength Range: Validation against Huygens Atmospheric and Surface Measurements and Application to the Cassini/VIMS Observations of the Dragonfly Landing Area

We present an analysis of Titan data acquired by the Cassini Visual and Infrared Mapping Spectrometer (VIMS) at the landing site of the Dragonfly mission, using a new version of our radiative transfer model for Titan, with significant updates for the spectroscopic parameters of atmospheric gases and photochemical aerosols. Our updated radiative transfer model is validated against the in situ spectroscopic measurements of the Huygens probe during its descent and once landed. We confirm that aerosols with a fractal dimension of 2.3-2.4 provide the best fit to the observations. We apply our radiative transfer model to four VIMS data cubes over the Selk crater region including the Dragonfly landing and exploration areas, further validating our model by producing consistent aerosol population and surface albedo maps. These infrared albedo maps, further corrected from the photometry, enable us to study the Selk crater region in terms of surface composition, landscape formation, and evolution. Our results suggest that the Selk crater is in an intermediate state of degradation and that the mountainous terrains of the area (including the crater rim and ejecta) are likely to be dominated by fine grains of tholin-like sediment. This organic sediment would be transported to the lowlands (crater floor and surrounding plains), possibly with water ice particles, by rivers, and further deposited and processed to form the sand particles that feed the neighboring dune fields. These results provide information for the operational and scientific preparation of the Dragonfly mission, paving the way for future exploration of Titan's surface composition and geology.

Keywords: titan; radiative transfer; near infrared astronomy; planetary atmospheres; planetary surfaces
Detection of a Disk Surrounding the Variably Accreting Young Star HBC722

We present new ALMA 233 GHz continuum observations of the FU Orionis Object HBC722. With these data we detect HBC722 at millimeter wavelengths for the first time, use this detection to calculate a circumstellar disk mass of 0.024 M⊙, and discuss implications for the burst triggering mechanism.

Keywords: star formation; fu orionis stars
Automated SpectroPhotometric Image REDuction (ASPIRED)

We provide a suite of public open-source spectral data-reduction software to rapidly obtain scientific products from all forms of long-slit-like spectroscopic observations. Automated SpectroPhotometric REDuction (ASPIRED) is a PYTHON-based spectral data-reduction toolkit. It is designed to be a general toolkit with high flexibility for users to refine and optimize their data-reduction routines for the individual characteristics of their instruments. The default configuration is suitable for low-resolution long-slit spectrometers and provides a quick-look quality output. However, for repeatable science-ready reduced spectral data, some moderate one-time effort is necessary to modify the configuration. Fine-tuning and additional (pre)processing may be required to extend the reduction to systems with more complex setups. It is important to emphasize that although only a few parameters need updating, ensuring their correctness and suitability for generalization to the instrument can take time due to factors such as instrument stability. We compare some example spectra reduced with ASPIRED to published data processed with IRAF-based and STARLINK-based pipelines, and find no loss in the quality of the final product. The PYTHON-based, IRAF-free ASPIRED can significantly ease the effort of an astronomer in constructing their own data-reduction workflow, enabling simpler solutions to data-reduction automation. This availability of near-real-time, science-ready data will allow adaptive observing strategies, particularly important in, but not limited to, time-domain astronomy.

Keywords: astronomy data reduction; spectroscopy; open source software; publicly available software; astronomy software; observational astronomy; astronomical techniques; astronomical methods
Boundary Layers of Circumplanetary Disks around Spinning Planets. I. Effects of Rossby Waves

Gas giant planets are believed to accrete from their circumplanetary disks (CPDs). The CPDs usually involve accretion through the boundary layer (BL) in the vicinity of planets. Prior studies have concentrated on the BL of nonspinning planets. We investigate the influence of planetary spin on the wave behaviors within the BL. The rotation profile in such BLs would show a sharp transition from the rigid rotation to the Keplerian rotation. We examine the angular momentum transport in these BLs in terms of linear perturbation analysis. We find that the global inertia-acoustic mode associated with spinning planets would give rise to the inflow of angular momentum and the accretion of gas. In this work, we identify a new kind of global mode, namely the Rossby mode. The Rossby mode can lead to the outflow of angular momentum and the decretion of gas from a spinning planet. The Rossby mode provides a negative feedback that regulates the planetary spin and mass. We compare the growth rate of the two modes as a function of the width of BL, the Mach number, and the spin rate of planets. Our results reveal the underlying hydrodynamic mechanism of terminal spins and asymptotic mass of the giant planets.

Keywords: exoplanet formation; planet formation; planetary-disk interactions; exoplanet atmospheric dynamics; exoplanet dynamics; accretion
Unfolding Drift Effects for Cosmic Rays over the Period of the Sun's Magnetic Field Reversal

A well-established, comprehensive 3D numerical modulation model is applied to simulate galactic protons, electrons, and positrons from 2011 May to 2015 May, including the solar magnetic polarity reversal of Solar Cycle 24. The objective is to evaluate how simulations compare with corresponding Alpha Magnetic Spectrometer observations for 1.0-3.0 GV and what underlying physics follows from this comparison to improve our understanding of how the major physical modulation processes change, especially particle drift, from a negative to a positive magnetic polarity cycle. Apart from their local interstellar spectra, electrons and positrons differ only in their drift patterns, but they differ with protons in other ways such as adiabatic energy changes at lower rigidity. In order to complete the simulations for oppositely charged particles, antiproton modeling results are also obtained. Together, observations and corresponding modeling indicate the difference in the drift pattern before and after the recent polarity reversal and clarify to a large extent the phenomenon of charge-sign dependence during this period. The effect of global particle drift became negligible during this period of no well-defined magnetic polarity. The resulting low values of particles' mean free paths (MFPs) during the polarity reversal contrast their large values during solar minimum activity and as such expose the relative contributions and effects of the different modulation processes from solar minimum to maximum activity. We find that the drift scale starts recovering just after the polarity reversal, but the MFPs keep decreasing or remain unchanged for some time after the polarity reversal.

Keywords: galactic cosmic rays; heliosphere
A Chandra X-Ray Survey of Optically Selected AGN Pairs

We present a Chandra archival study of optically selected active galactic nucleus (AGN) pairs at a median redshift $\bar{z}\sim 0.1$ . Out of 1286 AGN pairs (with projected separations rp < 100 kpc and velocity offsets Δv < 600 km s-1) optically identified from the Sloan Digital Sky Survey Seventh Data Release, we find 67 systems with archival Chandra observations, which represents the largest sample of optically selected AGN pairs studied in the X-ray. Among the 67 AGN pairs, 21 systems have both nuclei detected in the X-ray, 36 have one nucleus detected in the X-ray, and 10 have no X-ray detection. The X-ray detection rate, 78/134 = 58% (±7% 1σ Poisson errors), is significantly higher than that (23/134 = 17% ± 4%) of a comparison sample of star-forming galaxy pairs, lending support to the optical AGN classification. In the conservative case where X-ray contamination from star formation is removed, the X-ray detection rate becomes 27% ± 4%, consistent with predictions from the latest galaxy merger simulations. The 2-10 keV X-ray luminosity L2-10 keV increases with decreasing projected separation in AGN pairs for rp ≳ 15 kpc, suggesting an enhancement of black hole accretion even in early-stage mergers. On the other hand, L2-10 keV appears to decrease with decreasing projected separation at rp ≲15 kpc, which is contradictory to predictions from merger simulations. The apparent decrease in L2-10 keV of AGN pairs at rp ≲ 15 kpc may be caused by (i) enhanced absorbing columns from merger-induced gas inflows, (ii) feedback effects from early-stage mergers, and/or (iii) small number statistics. Future X-ray studies with larger samples are needed to put our results on firmer statistical ground.

Keywords: black hole physics; galaxy pairs; galaxy nuclei; x-ray active galactic nuclei
Deep Attention-based Supernovae Classification of Multiband Light Curves

In astronomical surveys, such as the Zwicky Transient Facility, supernovae (SNe) are relatively uncommon objects compared to other classes of variable events. Along with this scarcity, the processing of multiband light curves is a challenging task due to the highly irregular cadence, long time gaps, missing values, few observations, etc. These issues are particularly detrimental to the analysis of transient events: SN-like light curves. We offer three main contributions: (1) Based on temporal modulation and attention mechanisms, we propose a deep attention model (TimeModAttn) to classify multiband light curves of different SN types, avoiding photometric or hand-crafted feature computations, missing-value assumptions, and explicit imputation/interpolation methods. (2) We propose a model for the synthetic generation of SN multiband light curves based on the Supernova Parametric Model, allowing us to increase the number of samples and the diversity of cadence. Thus, the TimeModAttn model is first pretrained using synthetic light curves. Then, a fine-tuning process is performed. The TimeModAttn model outperformed other deep learning models, based on recurrent neural networks, in two scenarios: late-classification and early-classification. Also, the TimeModAttn model outperformed a Balanced Random Forest (BRF) classifier (trained with real data), increasing the balanced-F 1score from ≈.525 to ≈.596. When training the BRF with synthetic data, this model achieved a similar performance to the TimeModAttn model proposed while still maintaining extra advantages. (3) We conducted interpretability experiments. High attention scores were obtained for observations earlier than and close to the SN brightness peaks. This also correlated with an early highly variability of the learned temporal modulation.

Keywords: astroinformatics; astrostatistics; neural networks; supernovae; time series analysis; light curve classification; surveys; type ia supernovae; random forests
On the Mass Ratio Distribution of Black Hole Mergers in Triple Systems

Observations have shown that the majority of massive stars, the progenitors of black holes (BHs), have on average more than one stellar companion. In triple systems, wide inner binaries can be driven to a merger by a third body due to long-term secular interactions, most notably by the eccentric Lidov-Kozai effect. In this study, we explore the properties of BH mergers in triple systems and compare their population properties to those of binaries produced in isolation and assembled in dense star clusters. Using the same stellar physics and identical assumptions for the initial populations of binaries and triples, we show that stellar triples yield a significantly flatter mass ratio distribution from q = 1 down to q ~ 0.3 than either binary stars or dense stellar clusters, similar to the population properties inferred from the most recent catalog of gravitational-wave events, though we do not claim that all the observed events can be accounted for with triples. While hierarchical mergers in clusters can also produce asymmetric mass ratios, the unique spins of such mergers can be used to distinguish them from those produced from stellar triples. All three channels occupy distinct regions in the total mass-mass ratio space, which may allow them to be disentangled as more BH mergers are detected by LIGO, Virgo, and KAGRA.

Keywords: black holes; gravitational waves; trinary stars
Comparisons of Type Ia Supernova Light Curves in the UV and Optical with the Swift Ultra-violet/Optical Telescope

We examine the light-curve parameters of 97 nearby Type Ia supernovae (SN Ia) in the ultraviolet and optical using observations from the Swift Ultra-violet/Optical Telescope. Our light-curve models used linear combinations of templates, which were based on functional principal component analysis of the optical photometry of SN Ia. The weights for each principal component used in the fit capture certain aspects of the light-curve properties. We find that there is little difference in the overall variability of principal component scores across filters. We also find correlations between certain filters and PC components, indicating that the UV and optical properties seem to be tied together. This is a promising step in UV SN Ia analysis and suggests that UV light curves may be used to infer optical properties, paving the way for future cosmological studies.

Keywords: type ia supernovae; ultraviolet astronomy; ultraviolet photometry; optical astronomy
Comparing Plasma Anisotropy Associated with Solar Wind Discontinuities and Alfvénic Fluctuations

Solar wind magnetic field fluctuations exhibit a complex multiscale nature, often encompassing ion-scale discontinuities and MHD-scale Alfvénic fluctuations. Both of these types of structures are thought to play a critical role in plasma heating and turbulence dissipation. Here we comparatively analyze the plasma pressure anisotropies within discontinuities and adjacent Alfvénic fluctuations, leveraging unique solar wind observations from orbit conjunctions between the ARTEMIS and WIND missions, along the same flow streamline, though about 150 Earth radii apart. Based on 11 cases of such observations, we compare direct measurements of plasma anisotropy from particle instruments with its estimates from anisotropic MHD theory using the ratios of correlated ion velocity and Alfvén speed variations Δ v i /Δ v A. We find that (1) sporadically observed discontinuities associated with bifurcated reconnection current sheets harbor significant parallel electron anisotropies of >0.2; (2) direct electron measurements in all events reveal a median anisotropy of ~0.07 for Alfvénic fluctuations and ~0.17 for discontinuities; (3) anisotropic MHD predicts even more disparate total anisotropies within Alfvénic fluctuations and discontinuities, with a median value of ~0.15 for the former and ~0.57 for the latter; (4) the differences between theory-predicted and directly measured anisotropies imply that the ion contribution to anisotropy is significant and likely dominant within both types of structures, an assertion which we partly verify using simultaneous ion measurements from WIND. Our observations confirm that such discontinuities play a uniquely important role in producing solar wind plasma heating and anisotropy.

Keywords: solar wind; interplanetary turbulence; heliosphere; alfven waves; space plasmas; interplanetary discontinuities; interplanetary particle acceleration; solar magnetic reconnection; solar magnetic fields
Collision between Radiative and Adiabatic Supersonic Flows

The self-similar dynamics of the collision between radiative and adiabatic supersonic planar flows are performed assuming homogeneous radiation cooling. New self-similar solutions relevant to both astrophysical objects and laboratory experiments are derived. Numerical simulations investigate the formation of the radiative cooling shock in the interstellar medium and laboratory Xenon plasma to demonstrate the self-similarity of the interaction in the special case of balanced ram pressure. When the radiation cooling is inhomogeneous, the flow can become thermally unstable and deviate from the self-similar solution.

Keywords: shocks; cooling flows; laboratory astrophysics
Constraining Primordial Black Holes with Dwarf Galaxy Heating

Black holes formed in the early universe, prior to the formation of stars, can exist as dark matter and also contribute to the black hole merger events observed in gravitational waves. We set a new limit on the abundance of primordial black holes (PBHs) by considering interactions of PBHs with the interstellar medium, which result in the heating of gas. We examine generic heating mechanisms, including emission from the accretion disk, dynamical friction, and disk outflows. Using the data from the Leo T dwarf galaxy, we set a new cosmology-independent limit on the abundance of PBHs in the mass range ${ \mathcal O }(1){M}_{\odot }\mbox{--}{10}^{7}{M}_{\odot }$ , relevant for the recently detected gravitational-wave signals from intermediate-mass BHs.

Keywords: primordial black holes; dark matter; astrophysical processes
Detection of a High-velocity Prominence Eruption Leading to a CME Associated with a Superflare on the RS CVn-type Star V1355 Orionis

Stellar coronal mass ejections (CMEs) have recently received much attention for their impacts on exoplanets and stellar evolution. Detecting prominence eruptions, the initial phase of CMEs, as the blueshifted excess component of Balmer lines is a technique to capture stellar CMEs. However, most of prominence eruptions identified thus far have been slow and less than the surface escape velocity. Therefore, whether these eruptions were developing into CMEs remained unknown. In this study, we conducted simultaneous optical photometric observations with Transiting Exoplanet Survey Satellite and optical spectroscopic observations with the 3.8 m Seimei Telescope for the RS CVn-type star V1355 Orionis that frequently produces large-scale superflares. We detected a superflare releasing 7.0 × 1035 erg. In the early stage of this flare, a blueshifted excess component of Hα extending its velocity up to 760-1690 km s-1 was observed and thought to originate from prominence eruptions. The velocity greatly exceeds the escape velocity (i.e., ~350 km s-1), which provides important evidence that stellar prominence eruptions can develop into CMEs. Furthermore, we found that the prominence is very massive (9.5 × 1018 g < M < 1.4 × 1021 g). These data will clarify whether such events follow existing theories and scaling laws on solar flares and CMEs even when the energy scale far exceeds solar cases.

Keywords: stellar flares; stellar coronal mass ejections; stellar mass loss
GRB 190829A-A Showcase of Binary Late Evolution

GRB 190829A is the fourth-closest gamma-ray burst to date (z = 0.0785). Owing to its wide range of radio, optical, X-ray, and very-high-energy observations by HESS, it has become an essential new source that has been examined by various models with complementary approaches. Here, we show in GRB 190829A that the double prompt pulses and the three multiwavelength afterglows are consistent with the type II binary-driven hypernova model. The progenitor is a binary composed of a carbon-oxygen (CO) star and a neutron star (NS) companion. The gravitational collapse of the iron core of the CO star produces a supernova (SN) explosion and leaves behind a new NS (νNS) at its center. The accretion of the SN ejecta onto the NS companion and onto the νNS via matter fallback spins up the NSs and produces the double-peak prompt emission. The synchrotron emission from the expanding SN ejecta, with energy injection from the rapidly spinning νNS and its subsequent spindown, leads to the afterglow in the radio, optical, and X-ray bands. We model the sequence of physical and related radiation processes in BdHNe, and focus on individuating the binary properties that play the relevant roles.

Keywords: gamma-ray bursts; black hole physics; neutron stars; supernovae; type ic supernovae
A Perfect Tidal Storm: HD 104067 Planetary Architecture Creating an Incandescent World

The discovery of planetary systems beyond the solar system has revealed a diversity of architectures, most of which differ significantly from our system. The initial detection of an exoplanet is often followed by subsequent discoveries within the same system as observations continue, measurement precision is improved, or additional techniques are employed. The HD 104067 system is known to consist of a bright K-dwarf host star and a giant planet in a ∼55 days period eccentric orbit. Here we report the discovery of an additional planet within the HD 104067 system, detected through the combined analysis of radial velocity (RV) data from the High Resolution Echelle Spectrometer and High Accuracy Radial velocity Planet Searcher instruments. The new planet has a mass similar to Uranus and is in an eccentric ∼14 days orbit. Our injection-recovery analysis of the RV data exclude Saturn-mass and Jupiter-mass planets out to 3 au and 8 au, respectively. We further present Transiting Exoplanet Survey Satellite observations that reveal a terrestrial planet candidate (R p = 1.30 ± 0.12 R ⊕) in a ∼2.2 days period orbit. Our dynamical analysis of the three planet model shows that the two outer planets produce significant eccentricity excitation of the inner planet, resulting in tidally induced surface temperatures as high as ∼2600 K for an emissivity of unity. The terrestrial planet candidate may therefore be caught in a tidal storm, potentially resulting in its surface radiating at optical wavelengths.

Keywords: exoplanets; exoplanet systems; exoplanet tides; exoplanet dynamics; orbits; planetary dynamics; radial velocity; photometry
PEARLS: Near-infrared Photometry in the JWST North Ecliptic Pole Time Domain Field

We present near-infrared (NIR) ground-based Y, J, H, and K imaging obtained in the James Webb Space Telescope (JWST) North Ecliptic Pole Time Domain Field (NEP TDF) using the MMT-Magellan Infrared Imager and Spectrometer on the MMT. These new observations cover a field of approximately 230 arcmin2 in Y, H, and K, and 313 arcmin2 in J. Using Monte Carlo simulations, we estimate a 1σ depth relative to the background sky of (Y, J, H, K) = (23.80, 23.53, 23.13, 23.28) in AB magnitudes for point sources at a 95% completeness level. These observations are part of the ground-based effort to characterize this region of the sky, supplementing space-based data obtained with Chandra, NuSTAR, XMM, AstroSat, Hubble Space Telescope, and JWST. This paper describes the observations and reduction of the NIR imaging and combines these NIR data with archival imaging in the visible, obtained with the Subaru Hyper-Suprime-Cam, to produce a merged catalog of 57,501 sources. The new observations reported here, plus the corresponding multiwavelength catalog, will provide a baseline for time-domain studies of bright sources in the NEP TDF. * Partly based on observations taken with the MMT, a joint facility operated by the University of Arizona and the Smithsonian Institution.

Keywords: galaxy evolution; galaxy photometry; galaxy counts; catalogs; surveys