Table of contents

Located at Dome A, the highest point of the Antarctic plateau, the Chinese Kunlun station is considered to be one of the best ground-based photometric sites because of its extremely cold, dry, and stable atmosphere. A target can be monitored from there for over 40 days without diurnal interruption during a polar winter. This makes Kunlun station a perfect site to search for short-period transiting exoplanets. Since 2008, an observatory has existed at Kunlun station, and three telescopes are working there. Using these telescopes, the AST3 project has been carried out over the last 6 yr with a search for transiting exoplanets as one of its key programs (CHESPA). In the austral winters of 2016 and 2017, a set of target fields in the southern continuous viewing zone (CVZ) of TESS were monitored by the AST3-II telescope. In this paper, we introduce the CHESPA and present the first data release containing photometry of 26,578 bright stars (${{\boldsymbol{m}}}_{i}\leqslant 15$). The best photometric precision at the optimum magnitude for the survey is around 2 mmag. To demonstrate the data quality, we also present a catalog of 221 variables with a brightness variation greater than 5 mmag from the 2016 data. Among these variables, 179 are newly identified periodic variables not listed in the AAVSO database (https://www.aavso.org/), and 67 are listed in the Candidate Target List. These variables will require careful attention to avoid false-positive signals when searching for transiting exoplanets. Dozens of new transiting exoplanet candidates will be released in a subsequent paper.

We report first results from the CHinese Exoplanet Searching Program from Antarctica (CHESPA)—a wide-field high-resolution photometric survey for transiting exoplanets carried out using telescopes of the AST3 (Antarctic Survey Telescopes times 3) project. There are now three telescopes (AST3-I, AST3-II, and CSTAR-II) operating at Dome A—the highest point on the Antarctic Plateau—in a fully automatic and remote mode to exploit the superb observing conditions of the site, and its long and uninterrupted polar nights. The search for transiting exoplanets is one of the key projects for AST3. During the austral winters of 2016 and 2017 we used the AST3-II telescope to survey a set of target fields near the southern ecliptic pole, falling within the continuous viewing zone of the TESS mission. The first data release of the 2016 data, including images, catalogs, and light curves of 26,578 bright stars ($7.5\leqslant {{\boldsymbol{m}}}_{i}\leqslant 15$), was presented in Zhang et al. The best precision, as measured by the rms of the light curves at the optimum magnitude of the survey (${{\boldsymbol{m}}}_{i}=10$), is around 2 mmag. We detect 222 objects with plausible transit signals from these data, 116 of which are plausible transiting exoplanet candidates according to their stellar properties as given by the TESS Input Catalog, Gaia DR2, and TESS-HERMES spectroscopy. With the first data release from TESS expected in late 2018, this candidate list will be timely for improving the rejection of potential false-positives.

We present the results of a systematic search for molecular outflows in 68 Very Low Luminosity Objects (VeLLOs) from single-dish observations in CO isotopologues, finding 16 VeLLOs that show clear outflow signatures in the CO maps. Together with an additional three VeLLOs from the literature, we analyzed the outflow properties for these 19 VeLLOs, identifying 15 VeLLOs as proto-brown-dwarf (proto-BD) candidates and 4 VeLLOs as likely faint protostar candidates. The proto-BD candidates are found to have a mass accretion rate (∼10⁻⁸–10⁻⁷M_⊙ yr⁻¹) lower than that of the protostar candidates (≳10⁻⁶M_⊙ yr⁻¹). Their accretion luminosities are similar to or smaller than their internal luminosities, implying that many proto-BD candidates might have had either small accretion activity in a quiescent manner throughout their lifetimes, or be currently exhibiting relatively higher (or episodic) mass accretion than in the past. Outflows of many proto-BDs show strong trends of being less active if they are fainter or have less massive envelopes. The outflow forces and internal luminosities for more than half of the proto-BD candidates seem to follow the evolutionary track of a protostar with an initial envelope mass of ∼0.08 M_⊙, indicating that some BDs may form in less massive dense cores in a similar way to normal stars. But, because there also exists a significant fraction (about 40%) of proto-BDs with a much weaker outflow force than expected from the relations for protostars, we should not rule out the possibility of other formation mechanism for BDs.

We present preliminary trigonometric parallaxes of 184 late-T and Y dwarfs using observations from Spitzer (143), the U.S. Naval Observatory (18), the New Technology Telescope (14), and the United Kingdom Infrared Telescope (9). To complete the 20 pc census of ≥T6 dwarfs, we combine these measurements with previously published trigonometric parallaxes for an additional 44 objects and spectrophotometric distance estimates for another 7. For these 235 objects, we estimate temperatures, sift into five 150 K wide T_eff bins covering the range 300–1050 K, determine the completeness limit for each, and compute space densities. To anchor the high-mass end of the brown dwarf mass spectrum, we compile a list of early- to mid-L dwarfs within 20 pc. We run simulations using various functional forms of the mass function passed through two different sets of evolutionary code to compute predicted distributions in T_eff. The best fit of these predictions to our L, T, and Y observations is a simple power-law model with α ≈ 0.6 (where ${dN}/{dM}\propto {M}^{-\alpha }$), meaning that the slope of the field substellar mass function is in rough agreement with that found for brown dwarfs in nearby star-forming regions and young clusters. Furthermore, we find that published versions of the log-normal form do not predict the steady rise seen in the space densities from 1050 to 350 K. We also find that the low-mass cutoff to formation, if one exists, is lower than ∼5 M_Jup, which corroborates findings in young, nearby moving groups and implies that extremely low-mass objects have been forming over the lifetime of the Milky Way.

The role played by the large-scale environment in the nuclear activity of radio galaxies (RGs) is still not completely understood. Accretion mode, jet power, and galaxy evolution are connected with their large-scale environment on scales from tens to hundreds of kiloparsecs. Here we present a detailed statistical analysis of the large-scale environment for two samples of RGs up to redshifts z_src = 0.15. The main advantages of our study over studies in the literature are the extremely homogeneous selection criteria of the catalogs adopted to perform our investigation. This is also coupled with the use of several clustering algorithms. We performed a direct search of galaxy-rich environments around RGs by using them as beacons. To perform this study we also developed a new method that does not appear to suffer from a strong z_src dependence as other algorithms do. We conclude that, despite their radio morphological classification (FR I versus FR II) and/or their optical classification (high- or low-excitation radio galaxy (HERG or LERG)), RGs in the local universe tend to live in galaxy-rich large-scale environments that have similar characteristics and richness. We highlight that the fraction of FR I LERGs inhabiting galaxy-rich environments appears to be larger than that of FR II LERGs. We also found that five out of seven FR II HERGs, with z_src ≤ 0.11, lie in groups/clusters of galaxies. However, we recognize that, despite the high level of completeness of our catalogs, when restricting to the local universe, the low number of HERGs (∼10% of the total FR IIs investigated) prevents us drawing a strong statistical conclusion about this source class.

We present a new census of Galactic and extragalactic symbiotic stars (SySts). This compilation contains 323 known and 87 candidate SySts. Of the confirmed SySts, 257 are Galactic and 66 extragalactic. The spectral energy distributions (SEDs) of 348 sources have been constructed using 2MASS and AllWISE data. Regarding the Galactic SySts, 74% are S types, 13% D, and 3.5% D'. S types show an SED peak between 0.8 and 1.7 μm, whereas D types show a peak at longer wavelengths between 2 and 4 μm. D' types, on the other hand, display a nearly flat profile. Gaia distances and effective temperatures are also presented. According to their Gaia distances, S types are found to be members of both thin and thick Galactic disk populations, while S+IR and D types are mainly thin disk sources. Gaia temperatures show a reasonable agreement with the temperatures derived from SEDs within their uncertainties. A new census of the O viλ6830 Raman-scattered line in SySts is also presented. From a sample of 298 SySts with available optical spectra, 55% are found to emit the line. No significant preference is found among the different types. The report of the O viλ6830 Raman-scattered line in non-SySts is also discussed as well as the correlation between the Raman-scattered O vi line and X-ray emission. We conclude that the presence of the O vi Raman-scattered line still provides a strong criterion for identifying a source as a SySt.

This paper defines and discusses a set of rectangular all-sky projections that have no singular points, notably the Tesselated Octahedral Adaptive Spherical Transformation (or TOAST) developed initially for the WorldWide Telescope. These have proven to be useful as intermediate representations for imaging data where the application transforms dynamically from a standardized internal format to a specific format (projection, scaling, orientation, etc.) requested by the user. TOAST is strongly related to the Hierarchical Triangular Mesh pixelization and is particularly well adapted to situations where one wishes to traverse a hierarchy of images increasing in resolution. Because it can be recursively computed using a very simple algorithm it is particularly adaptable to use with graphical processing units.

Twenty years have passed since first light for the Sloan Digital Sky Survey (SDSS). Here, we release data taken by the fourth phase of SDSS (SDSS-IV) across its first three years of operation (2014 July–2017 July). This is the third data release for SDSS-IV, and the 15th from SDSS (Data Release Fifteen; DR15). New data come from MaNGA—we release 4824 data cubes, as well as the first stellar spectra in the MaNGA Stellar Library (MaStar), the first set of survey-supported analysis products (e.g., stellar and gas kinematics, emission-line and other maps) from the MaNGA Data Analysis Pipeline, and a new data visualization and access tool we call "Marvin." The next data release, DR16, will include new data from both APOGEE-2 and eBOSS; those surveys release no new data here, but we document updates and corrections to their data processing pipelines. The release is cumulative; it also includes the most recent reductions and calibrations of all data taken by SDSS since first light. In this paper, we describe the location and format of the data and tools and cite technical references describing how it was obtained and processed. The SDSS website (www.sdss.org) has also been updated, providing links to data downloads, tutorials, and examples of data use. Although SDSS-IV will continue to collect astronomical data until 2020, and will be followed by SDSS-V (2020–2025), we end this paper by describing plans to ensure the sustainability of the SDSS data archive for many years beyond the collection of data.

The census of Galactic H ii regions is vastly incomplete in the southern sky. We use the Australia Telescope Compact Array to observe 4–10 $\mathrm{GHz}$ radio continuum and hydrogen radio recombination line (RRL) emission from candidate H ii regions in the Galactic zone $259^\circ \lt {\ell }\lt 344^\circ ,| b| \lt 4^\circ$. In this first data release, we target the brightest H ii region candidates and observe 282 fields in the direction of at least one previously known or candidate H ii region. We detect radio continuum emission and RRL emission in 275 (97.5%) and 258 (91.5%) of these fields, respectively. We catalog the ∼7 GHz radio continuum peak flux densities and positions of 80 previously known and 298 candidate H ii regions. After averaging ∼18 RRL transitions, we detect 77 RRL velocity components toward 76 previously known H ii regions and 267 RRL velocity components toward 256 H ii region candidates. The discovery of RRL emission from these nebulae increases the number of known Galactic H ii regions in the surveyed zone by 82% to 568 nebulae. In the fourth quadrant, we discover 50 RRLs with positive velocities, placing those sources outside the solar circle. Including the pilot survey, the Southern H ɪɪ Region Discovery Survey has now discovered 295 Galactic H ii regions. In the next data release, we expect to add ∼200 fainter and more distant nebulae.

Radiative lifetimes for 104 levels of Erbium (Er) i in the energy range between 31,926.003 and 44,525.705 cm⁻¹ and 51 levels of Er ii from 31,381.779 to 47,840.962 cm⁻¹ were measured by a time-resolved laser-induced fluorescence method. Branching fraction (BF) determinations for 356 lines from 47 out of 104 Er i levels and 122 lines related to 19 out of 51 Er ii levels were completed based on the emission spectra of hollow cathode lamps recorded using the 1.0 m Fourier transform spectrometer and are available from the digital library of National Solar Observatory on Kitt Peak, USA (http://diglib.nso.edu/). By combining these BFs and the lifetime results measured in this work, absolute transition probabilities and oscillator strengths were determined for 352 lines of Er i and 92 lines of Er ii for the first time, increasing the total number of lines with experimental transition probabilities to over 910 for Er i and over 540 for Er ii.

We study a very young star-forming region in the outer Galaxy that is the most concentrated source of outflows in the Spitzer Space Telescope GLIMPSE360 survey. This region, dubbed CMa–l224, is located in the Canis Major OB1 association. CMa–l224 is relatively faint in the mid-infrared, but it shines brightly at the far-infrared wavelengths as revealed by the Herschel Space Observatory data from the Hi-GAL survey. Using the 3.6 and 4.5 μm data from the Spitzer/GLIMPSE360 survey, combined with the JHK_s Two Micron All Sky Survey (2MASS) and the 70–500 μm Herschel/Hi-GAL data, we develop young stellar object (YSO) selection criteria based on color–color cuts and fitting of the YSO candidates' spectral energy distributions with YSO 2D radiative transfer models. We identify 293 YSO candidates and estimate physical parameters for 210 sources well fit with YSO models. We select an additional 47 sources with GLIMPSE360-only photometry as "possible YSO candidates." The vast majority of these sources are associated with high H₂ column density regions and are good targets for follow-up studies. The distribution of YSO candidates at different evolutionary stages with respect to Herschel filaments supports the idea that stars are formed in the filaments and become more dispersed with time. Both the supernova-induced and spontaneous star formation scenarios are plausible in the environmental context of CMa–l224. However, our results indicate that a spontaneous gravitational collapse of filaments is a more likely scenario. The methods developed for CMa–l224 can be used for larger regions in the Galactic plane where the same set of photometry is available.

Spectra of a holmium hollow cathode discharge lamp with neon or argon as buffer gases have been measured with a Fourier Transform spectrometer. In the visible spectral range from 14,280 up to 25,000 cm⁻¹, or 400 to 700 nm, more than 4000 spectral lines were detected. Based on different signal-to-noise ratios in two spectra measured with different discharge conditions, we could distinguish between different elements and between different degrees of ionization of Ho. Altogether 2862 lines could be assigned to atomic Ho, 2417 of which had not been listed in literature up to now. Based on the known energy levels of atomic holmium, 987 lines have been classified, 627 of which have been classified for the first time.

Fourier Transform spectra of Holmium (Ho) in the visible spectral range from 14,280 up to 25,000 cm⁻¹, or 400 to 700 nm have been investigated, with a focus on the ionic lines. More than 500 spectral lines were assigned to singly ionized Ho (Ho ii), of which more than 400 were previously unknown. A further 21 lines were assigned to doubly ionized Ho (Ho iii), 1 of which was not reported previously. From among these lines, 60 Ho ii lines and 20 Ho iii lines were classified. A complete list of more than 4000 Ho lines observed in the recorded spectrum is supplied, even if they remain unclassified.

The coalescence of a binary neutron star gives rise to electromagnetic emission, known as a kilonova, that is powered by radioactive decays of r-process nuclei. Observations of a kilonova associated with GW170817 provide a unique opportunity to study heavy element synthesis in the universe. However, the atomic data of r-process elements are not yet complete enough to decipher the light curves and spectral features of kilonovae. In this paper, we perform extended atomic calculations of neodymium (Nd, Z = 60) to study the impact of the accuracy in atomic calculations on astrophysical opacities. By employing multiconfiguration Dirac–Hartree–Fock and relativistic configuration interaction methods, we calculate the energy levels and transition data of electric dipole transitions for Nd ii, Nd iii, and Nd iv ions. Compared with previous calculations, our new results provide better agreement with the experimental data. The energy level accuracies achieved in the present work are 10%, 3%, and 11% for Nd ii, Nd iii, and Nd iv, respectively, compared to the NIST database. We confirm that the overall properties of the opacity are not significantly affected by the accuracies of the atomic calculations. The impact on the Planck mean opacity is up to a factor of 1.5, which affects the timescale of kilonovae by at most 20%. However, we find that the wavelength-dependent features in the opacity are affected by the accuracies of the calculations. We emphasize that accurate atomic calculations, in particular for low-lying energy levels, are important to provide predictions of kilonova light curves and spectra.

We present the unWISE Catalog, containing the positions and fluxes of roughly 2 billion objects observed by the Wide-field Infrared Survey Explorer (WISE) over the full sky. The unWISE Catalog has two advantages over the existing WISE catalog (AllWISE): first, it is based on significantly deeper imaging, and second, it features improved modeling of crowded regions. The deeper imaging used in the unWISE Catalog comes from the coaddition of all publicly available 3–5 μm WISE imaging, including that from the ongoing NEOWISE-reactivation mission, thereby increasing the total exposure time by a factor of 5 relative to AllWISE. At these depths, even at high Galactic latitudes, many sources are blended with their neighbors; accordingly, the unWISE analysis simultaneously fits thousands of sources to obtain accurate photometry. Our new catalog detects sources roughly 0.7 magnitudes fainter than the AllWISE catalog at 5σ, and more accurately models millions of faint sources in the Galactic plane, enabling a wealth of Galactic and extragalactic science. In particular, relative to AllWISE, unWISE doubles the number of galaxies detected between redshifts 0 and 1 and triples the number between redshifts 1 and 2, cataloging more than half a billion galaxies over the whole sky.

We propose a revision of the system developed by Lépine et al. for spectroscopic M-subdwarf classification. Based on an analysis of subdwarf spectra and templates from Savcheva et al., we show that the CaH1 feature originally proposed by Gizis is important in selecting reliable cool subdwarf spectra. This index should be used in combination with the [TiO5, CaH2+CaH3] relation provided by Lépine et al. to avoid misclassification results. In the new system, the dwarf–subdwarf separators are first derived from a sample of more than 80,000 M dwarfs and a "labeled" subdwarf subsample, and these objects are all visually identified from their optical spectra. Based on these two samples, we refit the initial [TiO5, CaH1] relation and propose a new [CaOH, CaH1] relation supplementing the [TiO5, CaH1] relation to reduce the impact of uncertainty in flux calibration on classification accuracy. In addition, we recalibrate the ζ_TiO/CaH parameter defined in Lépine et al. to enable its successful application to Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectra. Using this new system, we select candidates from LAMOST Data Release 4 and finally identify a set of 2791 new M-subdwarf stars, covering the spectral sequence from type M0 to M7. This sample contains a large number of objects located at low Galactic latitudes, especially in the Galactic anti-center direction, expanding beyond previously published halo- and thick disk-dominated samples. Besides, we detect magnetic activity in 141 objects. We present a catalog for this M-subdwarf sample, including radial velocities, spectral indices and errors, and activity flags, with a compilation of external data (photometric and Gaia Data Release 2 astrometric parameters). The catalog is provided online, and the spectra can be retrieved from the LAMOST Data Release web portal.

Simulating and analyzing detailed observations of astrophysical sources for very high energy experiments, like the Cherenkov Telescope Array (CTA), can be a demanding task especially in terms of CPU consumption and required storage. In this context we propose an innovative cloud computing architecture based on Amazon Web Services (AWS) aiming to decrease the amount of time required to simulate and analyze a given field by distributing the workload and by exploiting the large computational power offered by AWS. We detail how the various services offered by the Amazon online platform are jointly used in our architecture, and we report a comparison of the execution times required for simulating observations of a test source with CTA, by a single machine and the cloud-based approach. We find that, using AWS, we can run our simulations more than 2 orders of magnitude faster than using a general purpose workstation for the same cost. We suggest considering this method when observations need to be simulated, analyzed, and concluded within short timescales.

We present the Massive and Distant Clusters of WISE Survey (MaDCoWS), a search for galaxy clusters at 0.7 ≲ z ≲ 1.5 based upon data from the Wide-field Infrared Survey Explorer (WISE) mission. MaDCoWS is the first cluster survey capable of discovering massive clusters at these redshifts over the full extragalactic sky. The search is divided into two regions—the region of the extragalactic sky covered by Pan-STARRS (δ > −30°) and the remainder of the southern extragalactic sky at δ < −30° for which shallower optical data from the SuperCOSMOS Sky Survey is available. In this paper, we describe the search algorithm, characterize the sample, and present the first MaDCoWS data release—catalogs of the 2433 highest amplitude detections in the WISE–Pan-STARRS region and the 250 highest amplitude detections in the WISE–SuperCOSMOS region. A total of 1723 of the detections from the WISE–Pan-STARRS sample have also been observed with the Spitzer Space Telescope, providing photometric redshifts and richnesses, and an additional 64 detections within the WISE–SuperCOSMOS region also have photometric redshifts and richnesses. Spectroscopic redshifts for 38 MaDCoWS clusters with IRAC photometry demonstrate that the photometric redshifts have an uncertainty of σ_z/(1 + z) ≃ 0.036. Combining the richness measurements with Sunyaev–Zel'dovich observations of MaDCoWS clusters, we also present a preliminary mass–richness relation that can be used to infer the approximate mass distribution of the full sample. The estimated median mass for the WISE–Pan-STARRS catalog is ${M}_{500}={1.6}_{-0.8}^{+0.7}\times {10}^{14}\,{M}_{\odot }$, with the Sunyaev–Zel'dovich data confirming that we detect clusters with masses up to M₅₀₀ ∼ 5 × 10¹⁴M_⊙ (M₂₀₀ ∼ 10¹⁵M_⊙).

We present a morphological classification of 14,245 radio active galactic nuclei (AGNs) into six types, i.e., typical Fanaroff–Riley Class I/II (FRI/II), FRI/II-like bent-tailed, X-shaped radio galaxy, and ringlike radio galaxy, by designing a convolutional neural network based autoencoder, namely MCRGNet, and applying it to a labeled radio galaxy (LRG) sample containing 1442 AGNs and an unlabeled radio galaxy (unLRG) sample containing 14,245 unlabeled AGNs selected from the Best–Heckman sample. We train MCRGNet and implement the classification task by a three-step strategy, i.e., pre-training, fine-tuning, and classification, which combines both unsupervised and supervised learnings. A four-layer dichotomous tree is designed to classify the radio AGNs, which leads to a significantly better performance than the direct six-type classification. On the LRG sample, our MCRGNet achieves a total precision of ∼93% and an averaged sensitivity of ∼87%, which are better than those obtained in previous works. On the unLRG sample, whose labels have been human-inspected, the neural network achieves a total precision of ∼80%. Also, using Sloan Digital Sky Survey Data Release 7 to calculate the r-band absolute magnitude (M_opt) and using the flux densities to calculate the radio luminosity (L_radio), we find that the distributions of the unLRG sources on the L_radio–M_opt plane do not show an apparent redshift evolution and could confirm with a sufficiently large sample that there could not exist an abrupt separation between FRIs and FRIIs as reported in some previous works.

The ambient solar wind conditions in interplanetary space and in the near-Earth environment are determined by activity on the Sun. Steady solar wind streams modulate the propagation behavior of interplanetary coronal mass ejections and are themselves an important driver of recurrent geomagnetic storm activity. The knowledge of the ambient solar wind flows and fields is thus an essential component of successful space weather forecasting. Here, we present an implementation of an operational framework for operating, validating, and optimizing models of the ambient solar wind flow on the example of Carrington Rotation 2077. We reconstruct the global topology of the coronal magnetic field using the potential field source surface model (PFSS) and the Schatten current sheet model (SCS) and discuss three empirical relationships for specifying the solar wind conditions near the Sun, namely the Wang–Sheeley (WS) model, the distance from the coronal hole boundary model (DCHB), and the Wang–Sheeley–Arge (WSA) model. By adding uncertainty in the latitude about the sub-Earth point, we select an ensemble of initial conditions and map the solutions to Earth by the Heliospheric Upwind eXtrapolation (HUX) model. We assess the forecasting performance from a continuous variable validation and find that the WSA model most accurately predicts the solar wind speed time series (RMSE ≈ 83 km s⁻¹). We note that the process of ensemble forecasting slightly improves the forecasting performance of all solar wind models investigated. We conclude that the implemented framework is well suited for studying the relationship between coronal magnetic fields and the properties of the ambient solar wind flow in the near-Earth environment.

A general framework for dealing with irradiation effects in the bolometric sense—specifically, reflection with heat absorption and the consequent redistribution of the absorbed heat—for systems of astrophysical bodies where the boundaries are used as support for the description of the processes, is presented. Discussed are its mathematical and physical properties, as well as its implementation approximations, with a focus on three plausible redistribution processes (uniform, latitudinal, and local redistribution). These are tested by extending PHOEBE 2.1 (http://phoebe-project.org/), the open-source package for modeling eclipsing binaries, and applied to a toy model of the known two-body eclipsing systems.

A new nonhydrostatic and cloud-resolving atmospheric model is developed for studying moist convection and cloud formation in planetary atmospheres. It is built on top of the Athena++ framework, utilizing its static/adaptive mesh-refinement, parallelization, curvilinear geometry, and dynamic task scheduling. We extend the original hydrodynamic solver to vapors, clouds, and precipitation. Microphysics is formulated generically so that it can be applied to both Earth and Jovian planets. We implemented the Low Mach number Approximate Riemann Solver for simulating low-speed atmospheric flows in addition to the usual Roe and Harten–Lax–van Leer-Contact (HLLC) Riemann solvers. Coupled with a fifth-order weighted essentially nonoscillatory subgrid-reconstruction method, the sharpness of critical fields such as clouds is well-preserved, and no extra hyperviscosity or spatial filter is needed to stabilize the model. Unlike many atmospheric models, total energy is used as the prognostic variable of the thermodynamic equation. One significant advantage of using total energy as a prognostic variable is that the entropy production due to irreversible mixing processes can be properly captured. The model is designed to provide a unified framework for exploring planetary atmospheres across various conditions, both terrestrial and Jovian. First, a series of standard numerical tests for Earth's atmosphere is performed to demonstrate the performance and robustness of the new model. Second, simulation of an idealized Jovian atmosphere in radiative-convective equilibrium shows that (1) the temperature gradient is superadiabatic near the water condensation level because of the changing of the mean molecular weight, and (2) the mean profile of ammonia gas shows a depletion in the subcloud layer down to nearly 10 bars. Relevance to the recent Juno observations is discussed.

We perform an extensive study of the influence of nuclear weak interactions on core-collapse supernovae, paying particular attention to consistency between nuclear abundances in the equation of state (EOS) and nuclear weak interactions. We compute properties of uniform matter based on the variational method. For inhomogeneous nuclear matter, we take a full ensemble of nuclei into account with various finite-density and thermal effects and directly use the nuclear abundances to compute nuclear weak interaction rates. To quantify the impact of a consistent treatment of nuclear abundances on CCSN dynamics, we carry out spherically symmetric CCSN simulations with full Boltzmann neutrino transport, systematically changing the treatment of weak interactions, EOSs, and progenitor models. We find that the inconsistent treatment of nuclear abundances between the EOS and weak interaction rates weakens the EOS dependence of both the dynamics and neutrino signals. We also test the validity of two artificial prescriptions for weak interactions of light nuclei and find that both prescriptions affect the dynamics. Furthermore, there are differences in neutrino luminosities by ∼10% and in average neutrino energies by 0.25–1 MeV from those of the fiducial model. We also find that the neutronization burst neutrino signal depends on the progenitor more strongly than on the EOS, preventing a detection of this signal from constraining the EOS.

Multi-band photometric and multi-object spectroscopic surveys of merging galaxy clusters allow for the characterization of the distributions of constituent DM and galaxy populations, constraints on the dynamics of the merging subclusters, and an understanding of galaxy evolution of member galaxies. We present deep photometric observations from Subaru/SuprimeCam and a catalog of 4431 spectroscopic galaxies from Keck/DEIMOS observations of 29 merging galaxy clusters ranging in redshift from z = 0.07 to 0.55. The ensemble is compiled based on the presence of radio relics, which highlight cluster-scale collisionless shocks in the intracluster medium. Together with the spectroscopic and photometric information, the velocities, timescales, and geometries of the respective merging events may be tightly constrained. In this preliminary analysis, the velocity distributions of 28 of the 29 clusters are shown to be well fit by single Gaussians. This indicates that radio-relic mergers largely occur transverse to the line of sight and/or near-apocenter. In this paper, we present our optical and spectroscopic surveys, preliminary results, and a discussion of the value of radio-relic mergers for developing accurate dynamical models of each system.

Observations of compact objects, in the form of radiation spectra, gravitational waves by LIGO/Virgo, and direct imaging with the Event Horizon Telescope, are currently the main information sources on plasma physics in extreme gravity. Modeling such physical phenomena Requires numerical methods that allow for the simulation of microscopic plasma dynamics in the presence of both strong gravity and electromagnetic fields. In Bacchini et al. (2018), we presented a detailed study of numerical techniques for the integration of free geodesic motion. Here, we extend the study by introducing electromagnetic forces in the simulation of charged particles in curved spacetimes. We extend the Hamiltonian energy-conserving method presented in Bacchini et al. (2018) to include the Lorentz force, and we test its performance compared to that of standard explicit Runge–Kutta and implicit midpoint rule schemes against analytic solutions. Then, we show the application of the numerical schemes to the integration of test particle trajectories in general relativistic magnetohydrodynamic (GRMHD) simulations by modifying the algorithms to handle grid-based electromagnetic fields. We test this approach by simulating ensembles of charged particles in a static GRMHD configuration obtained with the black hole accretion code (BHAC).