adsabs/SciX_UAT_keywords huggingface dataset:
The Relation between Gas-phase Metallicity and Stellar Mass Surface Density in Post-starburst E+A and E+A+ Galaxies within the Coma Cluster Observed by the SDSS-IV MaNGA Survey

We present an analysis of the Mass-Metallicity Relation (MZR) in 29 post-starburst galaxies in the Coma Cluster. Outward from the central dominant galaxy, NGC 4889, we conducted a conical survey of all galaxies observed by the Sloan Digital Sky Survey Data Release 17 (SDSS DR17) Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey within a 5° radius and redshift constraints 0.013 < z < 0.033. We identified 21 E+A galaxies and 8 "E+A+ galaxies" whose spectra matched the criteria of an E+A galaxy, but contain Balmer emission lines, indicating star formation. We utilized the MaNGA data to calculate each galaxy's star formation rate densities, gas-phase metallicity and stellar mass. We then compared the MZR between E+A galaxies and E+A+ galaxies to observe how varying star formation rates alter this relation.

Keywords: galaxy evolution; post-starburst galaxies; e+a galaxies; early-type galaxies; galaxies
An Arecibo 327 MHz Search for Radio Pulsars and Bursts in the Dwarf Irregular Galaxies Leo A and T

We have conducted an Arecibo 327MHz search of two dwarf irregular galaxies in the Local Group, Leo A and T, for radio pulsars and single pulses from fast radio bursts and other giant pulse emitters. We detected no astrophysical signals in this search, and we estimate flux density limits on both periodic and burst emission. Our derived luminosity limits indicate that only the most luminous radio pulsars known in our Galaxy and in the Magellanic Clouds (MCs) would have been detectable in our search if they were at the distances of Leo A and T. Given the much smaller stellar mass content and star formation rates of Leo A and T compared to the Milky Way and the MCs, there are likely to be few (if any) extremely luminous pulsars in these galaxies. It is therefore not surprising that we detected no pulsars in our search.

Keywords: radio transient sources; pulsars; dwarf irregular galaxies
The Formation of Monosubstituted Cyclopropenylidene Derivatives in the Interstellar Medium via Neutral-Neutral Reaction Pathways

Five substituted cyclopropenylidene derivatives (c-C3HX, X=CN, OH, F, NH2), all currently undetected in the interstellar medium (ISM), are found herein to have mechanistically viable, gas-phase formation pathways through neutral-neutral additions of ·X onto c-C3H2. The detection and predicted formation mechanism of c-C3HC2H introduces a need for the chemistry of c-C3H2 and any possible derivatives to be more fully explored. Chemically accurate CCSD(T)-F12/cc-pVTZ-F12 calculations provide exothermicities of additions of various radical species to c-C3H2, alongside energies of submerged intermediates that are crossed to result in product formation. Of the novel reaction mechanisms proposed, the addition of the cyano radical is the most exothermic at -16.10 kcal mol-1. All five products are found to or are expected to have at least one means of associating barrierlessly to form a submerged intermediate, a requirement for the cold chemistry of the ISM. The energetically allowed additions arise as a result of the strong electrophilicity of the radical species as well as the product stability gained through substituent-ring conjugation.

Keywords: astrochemistry; interdisciplinary astronomy; neutral-neutral reactions; quantum-chemical calculations
Panchromatic Simulated Galaxy Observations from the NIHAO Project

We present simulated galaxy spectral energy distributions (SEDs) from the far-ultraviolet (FUV) through the far-infrared (FIR), created using hydrodynamic simulations and radiative transfer calculations, suitable for the validation of SED modeling techniques. SED modeling is an essential tool for inferring star formation histories from nearby galaxy observations, but it is fraught with difficulty due to our incomplete understanding of stellar populations, chemical enrichment processes, and the nonlinear, geometry-dependent effects of dust on our observations. Our simulated SEDs will allow us to assess the accuracy of these inferences against galaxies with known ground truth. To create the SEDs, we use simulated galaxies from the Numerical Investigation of Hundred Astrophysical Objects suite and the radiative transfer code Stellar Kinematics Including Radiative Transfer. We explore different subgrid post-processing recipes, using color distributions and their dependence on axis ratios of galaxies in the nearby Universe to tune and validate them. We find that subgrid post-processing recipes that mitigate limitations in the temporal and spatial resolution of the simulations are required for producing FUV to FIR photometry that statistically reproduce the colors of galaxies in the nearby Universe. With this paper, we release resolved photometry and spatially integrated spectra for our sample galaxies, each from a range of different viewing angles. Our simulations predict that there is a large variation in attenuation laws among galaxies, and that from any particular viewing angle that energy balance between dust attenuation and re-emission can be violated by up to a factor of 3. These features are likely to affect SED modeling accuracy.

Keywords: galaxy evolution; radiative transfer; hydrodynamics; interstellar dust; stellar populations
Updated Spectral Characteristics for the Ultracool Dwarf TRAPPIST-1

A comprehensive infrared spectroscopic study of star TRAPPIST-1 is a crucial step toward the detailed examination of its planets. While the presence of Earth's atmosphere has limited the spectral extent of such a study up to now, the Near Infrared Imager and Slitless Spectrograph (NIRISS) and the Near Infrared Spectrograph instruments aboard the James Webb Space Telescope (JWST) can now yield the 0.6–5 μm spectral energy distribution (SED) of the star. Here we translate TRAPPIST-1's SED into tight constraints on its luminosity (L bol = 0.000566 ± 0.000022 L ⊙), effective temperature (T eff = 2569 ± 28 K), and metallicity ([Fe/H] = 0.052 ± 0.073) and investigate the behavior of its gravity-sensitive indices. Through band-by-band comparisons of the NIRISS and ground-based spectra, TRAPPIST-1 exhibits a blend of both field source and intermediate-gravity spectral characteristics, suggesting that the star is likely a field-age source with spectral features reminiscent of young objects. We also employ photospheric modeling incorporating theoretical and JWST spectra to constrain stellar surface heterogeneities, finding that the limited fidelity of current stellar spectral models precludes definitive constraints on the physical parameters of the distinct spectral components giving rise to TRAPPIST-1's photospheric heterogeneity and variability. In addition, we find intermodel differences in the inferences of properties (e.g., the effective temperature) over one order of magnitude larger than the instrument-driven uncertainties (∼100 K vs. ∼4 K), pointing toward a model-driven accuracy wall. Our findings call for a new generation of stellar models to support the optimal mining of JWST data and further constraining stellar—and ultimately planetary—properties.

Keywords: exoplanets; m dwarf stars; exoplanet systems
The K2 Galactic Archaeology Program Data Release 2: Asteroseismic Results from Campaigns 4, 6, and 7

Studies of Galactic structure and evolution have benefited enormously from Gaia kinematic information, though additional, intrinsic stellar parameters like age are required to best constrain Galactic models. Asteroseismology is the most precise method of providing such information for field star populations en masse, but existing samples for the most part have been limited to a few narrow fields of view by the CoRoT and Kepler missions. In an effort to provide well-characterized stellar parameters across a wide range in Galactic position, we present the second data release of red giant asteroseismic parameters for the K2 Galactic Archaeology Program (GAP). We provide ${\nu }_{\max }$ and ${\rm{\Delta }}\nu $ based on six independent pipeline analyses; first-ascent red giant branch (RGB) and red clump (RC) evolutionary state classifications from machine learning; and ready-to-use radius and mass coefficients, κR and κM, which, when appropriately multiplied by a solar-scaled effective temperature factor, yield physical stellar radii and masses. In total, we report 4395 radius and mass coefficients, with typical uncertainties of 3.3% (stat.) ± 1% (syst.) for κR and 7.7% (stat.) ± 2% (syst.) for κM among RGB stars, and 5.0% (stat.) ± 1% (syst.) for κR and 10.5% (stat.) ± 2% (syst.) for κM among RC stars. We verify that the sample is nearly complete—except for a dearth of stars with ${\nu }_{\max }\lesssim 10\mbox{--}20\,\mu \mathrm{Hz}$ —by comparing to Galactic models and visual inspection. Our asteroseismic radii agree with radii derived from Gaia Data Release 2 parallaxes to within 2.2% ± 0.3% for RGB stars and 2.0% ± 0.6% for RC stars.

Keywords: asteroseismology; catalogs; stellar radii; stellar masses; red giant clump; red giant branch
Validating AU Microscopii d with Transit Timing Variations

AU Mic is a young (22 Myr), nearby exoplanetary system that exhibits excess transit timing variations (TTVs) that cannot be accounted for by the two known transiting planets nor stellar activity. We present the statistical "validation" of the tentative planet AU Mic d (even though there are examples of "confirmed" planets with ambiguous orbital periods). We add 18 new transits and nine midpoint times in an updated TTV analysis to prior work. We perform the joint modeling of transit light curves using EXOFASTv2 and extract the transit midpoint times. Next, we construct an O-C diagram and use Exo-Striker to model the TTVs. We generate TTV log-likelihood periodograms to explore possible solutions for d's period, then follow those up with detailed TTV and radial velocity Markov Chain Monte Carlo modeling and stability tests. We find several candidate periods for AU Mic d, all of which are near resonances with AU Mic b and c of varying order. Based on our model comparisons, the most-favored orbital period of AU Mic d is 12.73596 ± 0.00793 days (T C,d = 2458340.55781 ± 0.11641 BJD), which puts the three planets near 4:6:9 mean-motion resonance. The mass for d is 1.053 ± 0.511 M ⊕, making this planet Earth-like in mass. If confirmed, AU Mic d would be the first known Earth-mass planet orbiting a young star and would provide a valuable opportunity in probing a young terrestrial planet's atmosphere. Additional TTV observations of the AU Mic system are needed to further constrain the planetary masses, search for possible transits of AU Mic d, and detect possible additional planets beyond AU Mic c.

Keywords: exoplanet astronomy; exoplanet dynamics; exoplanet systems; exoplanets
The First Dynamical Mass Determination of a Nitrogen-rich Wolf-Rayet Star Using a Combined Visual and Spectroscopic Orbit

We present the first visual orbit for the nitrogen-rich Wolf-Rayet binary, WR 133 (WN5o + O9I), based on observations made with the CHARA Array and the MIRC-X combiner. This orbit represents the first visual orbit for a WN star and only the third Wolf-Rayet star with a visual orbit. The orbit has a period of 112.8 days, a moderate eccentricity of 0.36, and a separation of a = 0.79 mas on the sky. We combine the visual orbit with an SB2 orbit and Gaia parallax to find that the derived masses of the component stars are ${M}_{{\rm{WR}}}=9.3\pm 1.6{M}_{\odot }$ and ${M}_{{\rm{O}}}=22.6\pm 3.2{M}_{\odot }$ , with the large errors owing to the nearly face-on geometry of the system combined with errors in the spectroscopic parameters. We also derive an orbital parallax that is identical to the Gaia-determined distance. We present a preliminary spectral analysis and atmosphere models of the component stars, and find the mass-loss rate in agreement with polarization variability and our orbit. However, the derived masses are low compared to the spectral types and spectral model. Given the close binary nature, we suspect that WR 133 should have formed through binary interactions, and represents an ideal target for testing evolutionary models given its membership in the cluster NGC 6871.

Keywords: interferometric binary stars; wolf-rayet stars; spectroscopic binary stars; wn stars; o supergiant stars; massive stars; stellar masses
An Analysis of the Eclipsing Binaries HD 71636, V1022 Cassiopeiae, and OT Andromedae

We have obtained high-dispersion spectroscopy and BV photometry of two F-type eclipsing binaries, HD 71636 and V1022 Cas, plus the A-type system OT And. Transiting Exoplanet Survey Satellite measurements for each system have also been incorporated. The photometry of HD 71636 enables a more consistent picture of this 5.01331 days, circular-orbit system to emerge. The F2 V primary has a mass of 1.506 ± 0.002 M ⊙ and a radius of 1.583 ± 0.024 R ⊙. The mass of the F5 V secondary is 1.282 ± 0.002 M ⊙, and its radius is 1.314 ± 0.030 R ⊙. Comparison with evolutionary models of the Modules for Experiments in Stellar Astrophysics (MESA) series results in a good fit for a composition of [Fe/H] = 0.12 and an age of 0.9 Gyr. For the F6 V stars of V1022 Cas, our analysis produces a period of 12.15616 days and an eccentricity of 0.312. The two components have nearly equal masses of 1.626 ± 0.001 M ⊙ and 1.607 ± 0.001 M ⊙. The radii of the primary and secondary are 2.570 ± 0.021 R ⊙ and 2.445 ± 0.022 R ⊙, respectively. Comparison with the MESA evolutionary models results in [Fe/H] = 0.08 and an age of 1.87 Gyr. OT And consists of a pair of similar mid-A stars that have an orbital period of 20.85292 days and an eccentricity of 0.215. The primary has a mass of 2.253 ± 0.014 M ⊙ and a radius of 3.167 ± 0.013 R ⊙. The corresponding parameters for the secondary are 2.147 ± 0.011 M ⊙ and 2.649 ± 0.015 R ⊙, respectively. The MESA series models produce a best fit for this system with [Fe/H] = 0.10 and an age of 0.675 Gyr. The total apsidal motion in both eccentric systems is less than 1.°5 century-1.

Keywords: spectroscopic binary stars; fundamental parameters of stars; eclipsing binary stars; detached binary stars
Empirically Constraining the Spectra of Stellar Surface Features Using Time-resolved Spectroscopy

Transmission spectroscopy is currently the technique best suited to study a wide range of planetary atmospheres, leveraging the filtering of a star's light by a planet's atmosphere rather than its own emission. However, as both a planet and its star contribute to the information encoded in a transmission spectrum, an accurate accounting of the stellar contribution is pivotal to enabling robust atmospheric studies. As current stellar models lack the required fidelity for such accounting, we investigate here the capability of time-resolved spectroscopy to yield high-fidelity, empirical constraints on the emission spectra of stellar surface heterogeneities (i.e., spots and faculae). Using TRAPPIST-1 as a test case, we simulate time-resolved JWST/NIRISS spectra and demonstrate that with a blind approach incorporating no physical priors, it is possible to constrain the photospheric spectrum to ≤0.5% and the spectra of stellar heterogeneities to within ≲10%, a precision that enables photon-limited (rather than model-limited) science. Now confident that time-resolved spectroscopy can propel the field in an era of robust high-precision transmission spectroscopy, we introduce a list of areas for future exploration to harness its full potential, including wavelength dependency of limb darkening and hybrid priors from stellar models as a means to further break the degeneracy between the position, size, and spectra of heterogeneities.

Keywords: exoplanets; stellar surfaces; transmission spectroscopy; astronomical techniques
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic Star Formation Rate Density 300 Myr after the Big Bang

We characterize the earliest galaxy population in the JADES Origins Field, the deepest imaging field observed with JWST. We make use of ancillary Hubble Space Telescope optical images (five filters spanning 0.4–0.9 μm) and novel JWST images with 14 filters spanning 0.8‑5 μm, including seven medium-band filters, and reaching total exposure times of up to 46 hr per filter. We combine all our data at >2.3 μm to construct an ultradeep image, reaching as deep as ≈31.4 AB mag in the stack and 30.3–31.0 AB mag (5σ, r = 0.″1 circular aperture) in individual filters. We measure photometric redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts z = 11.5‑15. These objects show compact half-light radii of R 1/2 ∼ 50‑200 pc, stellar masses of M ⋆ ∼ 107‑108 M ☉, and star formation rates ∼ 0.1‑1 M ☉ yr‑1. Our search finds no candidates at 15 < z < 20, placing upper limits at these redshifts. We develop a forward-modeling approach to infer the properties of the evolving luminosity function without binning in redshift or luminosity that marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the impact of nondetections. We find a z = 12 luminosity function in good agreement with prior results, and that the luminosity function normalization and UV luminosity density decline by a factor of ∼2.5 from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical models for evolution of the dark matter halo mass function.

Keywords: early universe; galaxy formation; galaxy evolution; high-redshift galaxies; reionization
Evolution of Switchbacks in the Inner Heliosphere

We analyze magnetic field data from the first six encounters of Parker Solar Probe, three Helios fast streams and two Ulysses south polar passes covering heliocentric distances 0.1 ≲ R ≲ 3 au. We use this data set to statistically determine the evolution of switchbacks of different periods and amplitudes with distance from the Sun. We compare the radial evolution of magnetic field variances with that of the mean square amplitudes of switchbacks, and quantify the radial evolution of the cumulative counts of switchbacks per kilometer. We find that the amplitudes of switchbacks decrease faster than the overall turbulent fluctuations, in a way consistent with the radial decrease of the mean magnetic field. This could be the result of a saturation of amplitudes and may be a signature of decay processes of large amplitude Alfvénic fluctuations in the solar wind. We find that the evolution of switchback occurrence in the solar wind is scale dependent: the fraction of longer-duration switchbacks increases with radial distance, whereas it decreases for shorter switchbacks. This implies that switchback dynamics is a complex process involving both decay and in situ generation in the inner heliosphere. We confirm that switchbacks can be generated by the expansion, although other types of switchbacks generated closer to the Sun cannot be ruled out.

Keywords: heliosphere; solar wind; interplanetary turbulence; alfven waves; space plasmas
Planetary Line-to-accretion Luminosity Scaling Relations: Extrapolating to Higher-order Hydrogen Lines

Aoyama et al. provided scaling relations between hydrogen-line luminosities and the accretion luminosity for planetary-mass objects. These fits should be an improvement over blind extrapolations of stellar relations. The fits go up only to the n = 8 electron energy level, but higher-n Balmer lines have been observed in the near-UV with UVES. We extend the scaling relations to higher-n levels for the Balmer and other series by fitting the fit coefficients (a, b) themselves and extrapolating them. Within the assumption of an accretion shock as the source of line emission, these fits should be robust for accreting planetary-mass objects.

Keywords: accretion; scaling relations; extrasolar gaseous giant planets; h i line emission; exoplanet formation; classical t tauri stars
The Role of Environment in Galaxy Evolution in the SERVS Survey. I. Density Maps and Cluster Candidates

We use photometric redshifts derived from new u-band through 4.5 μm Spitzer IRAC photometry in the 4.8 deg2 of the XMM-LSS field to construct surface density maps in the redshift range of 0.1-1.5. Our density maps show evidence for large-scale structure in the form of filaments spanning several tens of megaparsecs. Using these maps, we identify 339 overdensities that our simulated light-cone analysis suggests are likely associated with dark matter halos with masses, Mhalo, log(Mhalo/M⊙) > 13.7. From this list of overdensities we recover 43 of 70 known X-ray-detected and spectroscopically confirmed clusters. The missing X-ray clusters are largely at lower redshifts and lower masses than our target log(Mhalo/M⊙) > 13.7. The bulk of the overdensities are compact, but a quarter show extended morphologies that include likely projection effects, clusters embedded in apparent filaments, and at least one potential cluster merger (at z ∼ 1.28). The strongest overdensity in our highest-redshift slice (at z ∼ 1.5) shows a compact red galaxy core, potentially implying a massive evolved cluster.

Keywords: galaxy clusters; redshift surveys; large-scale structure of the universe; galaxy cluster counts
Bits Missing: Finding Exotic Pulsars Using bfloat16 on NVIDIA GPUs

The Fourier domain acceleration search (FDAS) is an effective technique for detecting faint binary pulsars in large radio astronomy data sets. This paper quantifies the sensitivity impact of reducing numerical precision in the graphics processing unit (GPU)-accelerated FDAS pipeline of the AstroAccelerate (AA) software package. The prior implementation used IEEE-754 single-precision in the entire binary pulsar detection pipeline, spending a large fraction of the runtime computing GPU-accelerated fast Fourier transforms. AA has been modified to use bfloat16 (and IEEE-754 double-precision to provide a "gold standard" comparison) within the Fourier domain convolution section of the FDAS routine. Approximately 20,000 synthetic pulsar filterbank files representing binary pulsars were generated using SIGPROC with a range of physical parameters. They have been processed using bfloat16, single-precision, and double-precision convolutions. All bfloat16 peaks are within 3% of the predicted signal-to-noise ratio of their corresponding single-precision peaks. Of 14,971 "bright" single-precision fundamental peaks above a power of 44.982 (our experimentally measured highest noise value), 14,602 (97.53%) have a peak in the same acceleration and frequency bin in the bfloat16 output plane, while in the remaining 369 the nearest peak is located in the adjacent acceleration bin. There is no bin drift measured between the single- and double-precision results. The bfloat16 version of FDAS achieves a speedup of approximately 1.6× compared to single-precision. A comparison between AA and the PRESTO software package is presented using observations collected with the GMRT of PSR J1544+4937, a 2.16 ms black widow pulsar in a 2.8 hr compact orbit.

Keywords: computational astronomy; astronomical methods; astronomy data analysis; astronomy software; computational methods; gpu computing; binary pulsars