adsabs/SciX_UAT_keywords huggingface dataset:
The All-sky Spectrometer of Hot Cosmic Plasma

The main instruments for analyzing the processes occurring in cosmic plasma are energy and mass analyzers of charged particle beams. The analyzers' operation is based on the separation of charged particles according to the energies of their motion or their masses in electric or magnetic fields. Currently, the top-hat analyzer is considered the main instrument for obtaining information about the state of cosmic plasma. However, it has a number of disadvantages: a significant time cycle for registering angular dependences in a total solid angle of 4π sr and low accuracy of determining the polar angles, which are associated with the need to rotate the analyzer during measurements. Over the past 20 years, plasma analyzers with a large viewing angle have been developed as an alternative to the top-hat analyzer. The design of the analyzer proposed in this work is capable of measuring plasma characteristics in a solid angle of 2π sr in one act of data registration. The all-sky spectrometer of hot cosmic plasma consists of two stages: the first stage is a conical lens of an original design, which serves to transform an extremely wide entrance flow of particles into a narrow cone-shaped beam; the second hexapole-cylindrical stage plays the role of an energy analyzer of a narrow cone-shaped flow. The paper describes the calculations and modeling of the proposed analyzer on the basis of original numerical and approximate analytical methods for designing systems of electron and ion optics. The main parameters of the device are calculated.

Keywords: spectrometers; space plasmas
The Chemical Inventory of the Planet-hosting Disk PDS 70

As host to two accreting planets, PDS 70 provides a unique opportunity to probe the chemical complexity of atmosphere-forming material. We present ALMA Band 6 observations of the PDS 70 disk and report the first chemical inventory of the system. With a spatial resolution of 0"4-0"5 (~50 au), 12 species are detected, including CO isotopologs and formaldehyde, small hydrocarbons, HCN and HCO+ isotopologs, and S-bearing molecules. SO and CH3OH are not detected. All lines show a large cavity at the center of the disk, indicative of the deep gap carved by the massive planets. The radial profiles of the line emission are compared to the (sub)millimeter continuum and infrared scattered light intensity profiles. Different molecular transitions peak at different radii, revealing the complex interplay between density, temperature, and chemistry in setting molecular abundances. Column densities and optical depth profiles are derived for all detected molecules, and upper limits obtained for the nondetections. Excitation temperature is obtained for H2CO. Deuteration and nitrogen fractionation profiles from the hydrocyanide lines show radially increasing fractionation levels. Comparison of the disk chemical inventory to grids of chemical models from the literature strongly suggests a disk molecular layer hosting a carbon-to-oxygen ratio C/O > 1, thus providing for the first time compelling evidence of planets actively accreting high C/O ratio gas at present time.

Keywords: astrochemistry; protoplanetary disks; exoplanet formation; interferometry; chemical abundances; circumstellar gas
The Formation of Star-forming Disks in the TNG50 Simulation

We investigate the disk formation process in the TNG50 simulation, examining the profiles of SFR surface density (ΣSFR), gas inflow and outflow, and the evolution of the angular momentum of inflowing gas particles. The TNG50 galaxies tend to have larger star-forming disks, and they also show larger deviations from exponential profiles in ΣSFR when compared to real galaxies in the Mapping Nearby Galaxies at APO survey. The stellar surface density of TNG50 galaxies show good exponential profiles, which is found to be the result of strong radial migration of stars over time. However, this strong radial migration of stars in the simulation produces flatter age profiles in TNG50 disks compared to observed galaxies. The star formation in the simulated galaxies is sustained by a net gas inflow, and this gas inflow is the primary driver for the cosmic evolution of star formation, as expected from simple gas-regulator models of galaxies. There is no evidence for any significant loss of angular momentum for the gas particles after they are accreted on to the galaxy, which may account for the large disk sizes in the TNG50 simulation. Adding viscous processes to the disks, such as the magnetic stresses from magnetorotational instability proposed by Wang & Lilly, will likely reduce the sizes of the simulated disks and the tension with the sizes of real galaxies, and this may produce more realistic exponential profiles.

Keywords: magnetohydrodynamical simulations; galaxy disks; star formation
Exploration of the Origin of Galactic and Extragalactic Star Clusters through Simulated H-R Diagrams

The present work explores the origin of the formation of star clusters in our Galaxy and in the Small Magellanic Cloud (SMC) through simulated H-R diagrams and compare those with observed star clusters. The simulation study produces synthetic H-R diagrams through the Markov Chain Monte Carlo (MCMC) technique using the star formation history (SFH), luminosity function (LF), abundance of heavy metal (Z), and a big library of isochrones as basic inputs and compares them with observed H-R diagrams of various star clusters. The distance-based comparison between those two diagrams is carried out through two-dimensional matching of points in the color-magnitude diagram (CMD) after the optimal choice of bin size and appropriate distance function. It is found that in a poor medium of heavy elements (Z = 0.0004), the Gaia LF along with a mixture of multiple Gaussian distributions of the SFH may be the origin of formation of globular clusters (GCs). On the contrary, an enriched medium (Z = 0.019) is generally favored with the Gaia LF along with a double power law or Beta-type (i.e., unimodal) SFH, for the formation of globular clusters. For SMC clusters, the choice of an exponential LF and exponential SFH is the proper combination for a poor medium, whereas the Gaia LF with a Beta-type SFH is preferred for the formation of star clusters in an enriched medium.

Keywords: hertzsprung russell diagram; galaxy evolution; globular star clusters; luminosity function
Assessing the Transiting Exoplanet Survey Satellite's Yield of Rocky Planets Around Nearby M Dwarfs

Terrestrial planets are easier to detect around M dwarfs than other types of stars, making them promising for next-generation atmospheric characterization studies. The Transiting Exoplanet Survey Satellite (TESS) mission has greatly increased the number of known M-dwarf planets that we can use to perform population studies, allowing us to explore how the rocky planet occurrence rate varies with host radius, following in the footsteps of past work with Kepler data. In this paper, we use simulations to assess TESS's yield of small (0.5 R ⊕ < R p < 2 R ⊕) planet candidates around nearby (d < 30 pc) M dwarfs. We highlight the underappreciated fact that, while TESS was indeed expected to find a large number of planets around M dwarfs overall, it was not expected to have a high planetary yield for the latest M dwarfs. Furthermore, we find that TESS has detected fewer planets around stars with R ⋆ < 0.3 R ⊙ than even was expected (11 observed versus 24 ± 5 expected). We find evidence that the photometric noise of stars in the TESS bandpass increases with decreasing radius for M dwarfs. However, this trend cannot explain the observed distribution of planets. Our main conclusions are (1) the planet occurrence rate likely does not increase, and may decrease for the latest M dwarfs; and (2) there are at least 17, and potentially three times that number, transiting planets around nearby late-M dwarfs that still will not be detected by the end of TESS's fourth year.

Keywords: exoplanet catalogs; extrasolar rocky planets; late-type dwarf stars; m dwarf stars
Directly Determined Properties of HD 97658 from Interferometric Observations

We conducted interferometric observations with the CHARA Array of transiting super-Earth host HD 97658 and measured its limb-darkened angular diameter to be θLD = 0.314 ± 0.004 mas. The combination of the angular diameter with the Gaia EDR3 parallax value with zero-point correction (π = 46.412 ± 0.022 mas, d =21.546 ± 0.011 pc) yields a physical radius of R⋆ = 0.728 ± 0.008 R⊙. We also measured the bolometric flux of the star to be Fbol = 2.42 ± 0.05 × 10-8 erg s-1 cm-2, which, together with angular size, allows a measurement of the effective temperature Teff = 5212 ± 43 K. Our directly determined physical stellar properties are in good agreement with previous estimates derived from spectroscopy. We used our measurements in combination with stellar evolutionary models and properties of the transit of HD 97658 b to determine the mass and age of HD 97658 as well as constrain the properties of the planet. Our results and our analysis of the TESS light curve on the planet (TOI-1821) corroborate previous studies of this system with tighter uncertainties.

Keywords: fundamental parameters of stars; interferometry; exoplanets; late-type stars
Minkowski Functionals of SDSS-III BOSS: Hints of Possible Anisotropy in the Density Field?

We present measurements of the Minkowski functionals extracted from the SDSS-III BOSS catalogs. After defining the Minkowski functionals, we describe how an unbiased reconstruction of these statistics can be obtained from a field with masked regions and survey boundaries, validating our methodology with Gaussian random fields and mock galaxy snapshot data. From the BOSS galaxy data, we generate a set of four density fields in three dimensions corresponding to the northern and southern skies of LOWZ and CMASS catalogs, smoothing over large scales (Gaussian smoothing scale of 35 Mpc) such that the field is perturbatively non-Gaussian. We extract the Minkowski functionals from each data set separately, and measure their shapes and amplitudes by fitting a Hermite polynomial expansion. For the shape parameter of the Minkowski functional curves a 0, that is related to the bispectrum of the field, we find that the LOWZ-South data presents a systematically lower value of a 0 = -0.080 ± 0.040 than its northern sky counterpart a 0 = 0.032 ± 0.024. Although the significance of this discrepancy is not very high, it potentially indicates some systematics in the data or that the matter density field exhibits anisotropy at low redshift. By assuming a standard isotropic flat ΛCDM cosmology, the amplitudes of the Minkowski functionals from the combination of northern and southern sky data give the constraints Ωc h 2 n s = 0.110 ± 0.006 and 0.111 ± 0.008 for CMASS and LOWZ, respectively, which is in agreement with the Planck ΛCDM best-fit Ωc h 2 n s = 0.116 ± 0.001.

Keywords: observational cosmology; large-scale structure of the universe; cosmic web
Developing Data-driven Artificial Neural Network for a High Throughput Retrieval of Aerosol Optical Depth and Surface Temperature of Mars

In this work, we aim to develop artificial neural network (ANN) techniques to reproduce the retrieval results of physical quantities from spacecraft observations of solar system bodies using radiative transfer methods. The particular application here is the retrieval of dust optical depth, water ice optical depth, and surface temperature on Mars using daytime observations obtained by the Thermal Emission Spectrometer on board the Mars Global Surveyor. Compared against the results obtained from traditional radiative transfer retrieval techniques, our ANN successfully recovered the three quantities using daytime observations. The principal advantage of these machine-learning algorithms is their complete automation and high throughput. Therefore, the algorithms presented here would be useful for very large data sets and would make practical the sampling of many different approximations or boundary conditions related to a given observation data set and retrieval problem.

Keywords: mars; neural networks; remote sensing
Simulating Jets from a Neutron Star Companion Hours after a Core-collapse Supernova

We conduct three-dimensional hydrodynamical simulations to explore the interaction of the jets that a neutron star (NS) companion to a type Ic or type Ib core-collapse supernova (CCSN) launches a few hours after explosion with the ejecta of the CCSN. We assume that an NS companion at 5 R⊙ from the exploding star accretes mass from the slower inner ejecta through an accretion disk, and that the disk launches two opposite jets. Although the energy of the jets is only about one percent of the total energy of the ejecta, it is comparable to the energy of the slower inner part of the ejecta. We find that the jets inflate one low-density hot bubble to one side of the ejecta, and that this bubble expands to influence ejecta gas up to expansion velocities of ${v}_{\mathrm{ej}}\simeq 3500\,\mathrm{km}\,{{\rm{s}}}^{-1}$ . The postshock jets' material develops a large meridional flow and small vortexes. The boundary between the ejecta and jets' postshock gases is unstable. The instabilities and vortexes mix jets' gas with the ejecta. We expect such a hot bubble to contribute to the light curve of CCSNe that are progenitors of binary NS systems, in particular to observers on the side of the bubble.

Keywords: high energy astrophysics; neutron stars; jets; compact binary stars; interacting binary stars; supernova dynamics; type ib supernovae; type ic supernovae; massive stars
A Scintillation Arc Survey of 22 Pulsars with Low to Moderate Dispersion Measures

Context. By providing information about the location of scattering material along the line of sight (LoS) to pulsars, scintillation arcs are a powerful tool for exploring the distribution of ionized material in the interstellar medium (ISM). Here, we present observations that probe the ionized ISM on scales of ~0.001-30 au. Aims. We have surveyed pulsars for scintillation arcs in a relatively unbiased sample with DM < 100 pc cm-3. We present multifrequency observations of 22 low to moderate DM pulsars. Many of the 54 observations were also observed at another frequency within a few days. Methods. For all observations, we present dynamic spectra, autocorrelation functions, and secondary spectra. We analyze these data products to obtain scintillation bandwidths, pulse broadening times, and arc curvatures. Results. We detect definite or probable scintillation arcs in 19 of the 22 pulsars and 34 of the 54 observations, showing that scintillation arcs are a prevalent phenomenon. The arcs are better defined in low DM pulsars. We show that well-defined arcs do not directly imply anisotropy of scattering. Only the presence of reverse arclets and a deep valley along the delay axis, which occurs in about 20% of the pulsars in the sample, indicates substantial anisotropy of scattering. Conclusions. The survey demonstrates substantial patchiness of the ionized ISM on both astronomical-unit-size scales transverse to the LoS and on ~100 pc scales along it. We see little evidence for distributed scattering along most lines of sight in the survey.

Keywords: radio pulsars; interstellar medium; interstellar scattering; radio astronomy; radio spectroscopy; warm ionized medium; stellar wind bubbles
A newly discovered southern HgMn star: HD 4065A

Evidence is presented that HD 4065A is a newly discovered HgMn star. The Hg II line at 3983.93 Å is present in two spectra acquired with the High Resolution Spectrograph mounted behind the South African Large Telescope and separated by about 2 months and 25 days. The lines on the second spectrum are redshifted reflecting the orbital motion of HD 4065A around the center of mass of a binary system. The far-ultraviolet spectrum, SWP 20399 collected with IUE, shows a strong resonance line of Ga II usually conspicuous in the far-ultraviolet spectra of HgMn star. A first spectrum synthesis of the spectral range from 3900 up to 4000 Å yields estimates of the abundances of calcium (0.10 solar), zirconium (25 solar) and mercury (50,000 solar).

Keywords: chemically peculiar stars
Formation of Interstellar Complex Polycyclic Aromatic Hydrocarbons: Insights from Molecular Dynamics Simulations of Dehydrogenated Benzene

Small organic molecules are thought to provide building blocks for the formation of complex interstellar polycyclic aromatic hydrocarbons (PAHs). However, the underlying chemical mechanisms remain unclear, particularly concerning the role of interstellar dust. Using molecular dynamics, we simulate the chemical reaction between dehydrogenated benzene molecules in the gas phase or on the surface of an onion-like carbon nanoparticle (NP). The reaction leads to the formation of PAHs of complex structures. The size of the formed molecules is found to roughly increase with increasing temperature up to 800 K, and to be correlated with the level of dehydrogenation. Morphology analysis features the formation of large rings that contain up to 32 carbon atom at high temperature. Density functional theory (DFT) calculations are performed to search the fundamental energetic reaction pathways. The DFT results quantitatively confirm the correlation between the reactivity and the dehydrogenation level, and the formation of stable C-8 rings. Moreover, the nanostructures formed on the NP surface point to a possible layer-by-layer formation mechanism for interstellar fullerene and carbon onions.

Keywords: astrochemistry; polycyclic aromatic hydrocarbons; interstellar molecules; molecule formation; interstellar medium
Dippers from the TESS Full-frame Images. I. Results of the First One Year Data and Discovery of a Runaway Dipper

We present a comprehensive catalog of the dippers—young stellar objects that exhibit episodic dimming—derived from one year's worth of data of the Transiting Exoplanet Survey Satellite (TESS) full-frame images. In the survey, we found 35 dippers using the convolutional neural network, most of them newly discovered. Although these dippers are widely distributed over the first half-hemisphere that TESS surveyed, we identified the majority's membership with the nearest association Scorpius-Centaurus, Velorum OB2, and the nearby Orion molecular cloud complex. However, several dippers are likely to be located in the field. We also found three old dippers whose age exceeds 10 million years, which is considered to be the disk dissipation time. The color-color diagram indicates that these old dippers are likely to have an extreme debris disk. In particular, we found a runaway old dipper having a large three-dimensional velocity of 72 km s-1. The dippers in the field, which were probably escaping from their birth molecular clouds or were born outside the current area of star-forming regions, are more common than previously considered.

Keywords: protoplanetary disks; variable stars; t tauri stars
Achievement of the Planetary Defense Investigations of the Double Asteroid Redirection Test (DART) Mission

NASA's Double Asteroid Redirection Test (DART) mission was the first to demonstrate asteroid deflection, and the mission's Level 1 requirements guided its planetary defense investigations. Here, we summarize DART's achievement of those requirements. On 2022 September 26, the DART spacecraft impacted Dimorphos, the secondary member of the Didymos near-Earth asteroid binary system, demonstrating an autonomously navigated kinetic impact into an asteroid with limited prior knowledge for planetary defense. Months of subsequent Earth-based observations showed that the binary orbital period was changed by –33.24 minutes, with two independent analysis methods each reporting a 1σ uncertainty of 1.4 s. Dynamical models determined that the momentum enhancement factor, β, resulting from DART's kinetic impact test is between 2.4 and 4.9, depending on the mass of Dimorphos, which remains the largest source of uncertainty. Over five dozen telescopes across the globe and in space, along with the Light Italian CubeSat for Imaging of Asteroids, have contributed to DART's investigations. These combined investigations have addressed topics related to the ejecta, dynamics, impact event, and properties of both asteroids in the binary system. A year following DART's successful impact into Dimorphos, the mission has achieved its planetary defense requirements, although work to further understand DART's kinetic impact test and the Didymos system will continue. In particular, ESA's Hera mission is planned to perform extensive measurements in 2027 during its rendezvous with the Didymos–Dimorphos system, building on DART to advance our knowledge and continue the ongoing international collaboration for planetary defense.

Keywords: asteroids; small solar system bodies; near-earth objects; asteroid satellites; planetary science; solar system astronomy; asteroid dynamics; asteroid surfaces; impact phenomena
deepCR: Cosmic Ray Rejection with Deep Learning

Cosmic ray (CR) identification and replacement are critical components of imaging and spectroscopic reduction pipelines involving solid-state detectors. We present deepCR, a deep-learning-based framework for CR identification and subsequent image inpainting based on the predicted CR mask. To demonstrate the effectiveness of this framework, we train and evaluate models on Hubble Space Telescope (HST) ACS/WFC images of sparse extragalactic fields, globular clusters, and resolved galaxies. We demonstrate that at a false-positive rate of 0.5%, deepCR achieves close to 100% detection rates in both extragalactic and globular cluster fields, and 91% in resolved galaxy fields, which is a significant improvement over the current state-of-the-art method LACosmic. Compared with a multicore CPU implementation of LACosmic, deepCR CR mask predictions run up to 6.5 times faster on a CPU and 90 times faster on a single GPU. For image inpainting, the mean squared errors of deepCR predictions are 20 times lower in globular cluster fields, 5 times lower in resolved galaxy fields, and 2.5 times lower in extragalactic fields, compared with the best performing nonneural technique tested. We present our framework and the trained models as an open-source Python project , with a simple-to-use API. To facilitate reproducibility of the results we also provide a benchmarking codebase .

Keywords: astronomy data reduction; convolutional neural networks; classification; neural networks; cosmic rays; hubble space telescope; astronomical detectors
Zwicky Transient Facility and Globular Clusters: Calibration of the gr-band Absolute Magnitudes for the Yellow Post-asymptotic-giant-branch Stars

We present the first absolute calibration for the yellow post-asymptotic-giant-branch (PAGB) stars in the g and r band based on time-series observations from the Zwicky Transient Facility. These absolute magnitudes were calibrated using four yellow PAGB stars (one nonvarying star and three Type II Cepheids) located in the globular clusters. We provide two calibrations of the gr-band absolute magnitudes for the yellow PAGB stars, by using an arithmetic mean and a linear regression. We demonstrate that the linear regression provides a better fit to the g-band absolute magnitudes for the yellow PAGB stars. These calibrated gr-band absolute magnitudes have a potential to be used as Population II distance indicators in the era of time-domain synoptic sky surveys.

Keywords: globular star clusters; post-asymptotic giant branch stars; wide-field telescopes; sky surveys; distance indicators