adsabs/SciX_UAT_keywords huggingface dataset:
The Roasting Marshmallows Program with IGRINS on Gemini South I: Composition and Climate of the Ultrahot Jupiter WASP-18 b

We present high-resolution dayside thermal emission observations of the exoplanet WASP-18 b using IGRINS on Gemini South. We remove stellar and telluric signatures using standard algorithms, and we extract the planet signal via cross-correlation with model spectra. We detect the atmosphere of WASP-18 b at a signal-to-noise ratio (S/N) of 5.9 using a full chemistry model, measure H2O (S/N = 3.3), CO (S/N = 4.0), and OH (S/N = 4.8) individually, and confirm previous claims of a thermal inversion layer. The three species are confidently detected (>4σ) with a Bayesian inference framework, which we also use to retrieve abundance, temperature, and velocity information. For this ultrahot Jupiter (UHJ), thermal dissociation processes likely play an important role. Retrieving abundances constant with altitude and allowing the temperature-pressure profile to adjust freely results in a moderately super-stellar carbon-to-oxygen ratio (C/O = ${0.75}_{-0.17}^{+0.14}$ ) and metallicity ([M/H] = ${1.03}_{-1.01}^{+0.65}$ ). Accounting for undetectable oxygen produced by thermal dissociation leads to C/O = ${0.45}_{-0.10}^{+0.08}$ and [M/H] = ${1.17}_{-1.01}^{+0.66}$ . A retrieval that assumes radiative-convective-thermochemical equilibrium and naturally accounts for thermal dissociation constrains C/O < 0.34 (2σ) and [M/H] = ${0.48}_{-0.29}^{+0.33}$ , in line with the chemistry of the parent star. Looking at the velocity information, we see a tantalizing signature of different Doppler shifts at the level of a few kilometers per second for different molecules, which might probe dynamics as a function of altitude and/or location on the planet disk. Our results demonstrate that ground-based, high-resolution spectroscopy at infrared wavelengths can provide meaningful constraints on the compositions and climate of highly irradiated planets. This work also elucidates potential pitfalls with commonly employed retrieval assumptions when applied to the spectra of UHJs.

Keywords: exoplanet atmospheres; exoplanet atmospheric composition; exoplanet atmospheric dynamics; exoplanet atmospheric structure; high resolution spectroscopy; infrared spectroscopy
Jupiter's Metastable Companions

Jovian co-orbitals share Jupiter's orbit and exhibit 1:1 mean-motion resonance with the planet. This includes >10,000 so-called Trojan asteroids surrounding the leading (L4) and trailing (L5) Lagrange points, viewed as stable groups dating back to planet formation. A small number of extremely transient horseshoe and quasi-satellite co-orbitals have been identified, which only briefly (<1,000 yr) exhibit co-orbital motions. Via an extensive numerical study, we identify for the first time some Trojans that are certainly only "metastable"; instead of being primordial, they are recent captures from heliocentric orbits into moderately long-lived (10 kyr–100 Myr) metastable states that will escape back to the scattering regime. We have also identified (1) the first two Jovian horseshoe co-orbitals that exist for many resonant libration periods and (2) eight Jovian quasi-satellites with metastable lifetimes of 4–130 kyr. Our perspective on the Trojan population is thus now more complex as Jupiter joins the other giant planets in having known metastable co-orbitals that are in steady-state equilibrium with the planet-crossing Centaur and asteroid populations; the 27 identified here are in agreement with theoretical estimates.

Keywords: jupiter trojans; celestial mechanics; n-body simulations
Relativistic MR-MP Energy Levels for K-like Fe

Relativistic Multi-Reference Møller-Plesset (MR-MP) many-body perturbation theory calculations are reported for the ground and excited states of Fe VIII. Energies are provided for states coming from the configurations 3sm3pn3dp4lq (l = s, p, d, and f) with m+n+p+q=9, p ≤ 3, and q ≤ 1. The MR-MP results were compared with the recommended observed values in the CHIANTI-v8 database and with previous ab-initio calculations. The MR-MP calculations reproduce 90% of the available observed values within 3500 cm-1. The previous accurate ab-initio calculations reproduce only 50% of the observed values within 3500 cm-1. The electronic structure of Fe VIII is very complex and our MR-MP results show that accurate calculations require the inclusion of not only 3s2-3d2, 3p2-3d2, and 3s3p-3d2 promotions but also of all electron correlations via perturbation theory.

Keywords: atomic data benchmarking; atomic spectroscopy; atomic physics; line positions
Search for sub-TeV Neutrino Emission from Novae with IceCube-DeepCore

The understanding of novae, the thermonuclear eruptions on the surfaces of white dwarf stars in binaries, has recently undergone a major paradigm shift. Though the bolometric luminosity of novae was long thought to arise directly from photons supplied by the thermonuclear runaway, recent gigaelectronvolt (GeV) gamma-ray observations have supported the notion that a significant portion of the luminosity could come from radiative shocks. More recently, observations of novae have lent evidence that these shocks are acceleration sites for hadrons for at least some types of novae. In this scenario, a flux of neutrinos may accompany the observed gamma rays. As the gamma rays from most novae have only been observed up to a few GeV, novae have previously not been considered as targets for neutrino telescopes, which are most sensitive at and above teraelectronvolt (TeV) energies. Here, we present the first search for neutrinos from novae with energies between a few GeV and 10 TeV using IceCube-DeepCore, a densely instrumented region of the IceCube Neutrino Observatory with a reduced energy threshold. We search both for a correlation between gamma-ray and neutrino emission as well as between optical and neutrino emission from novae. We find no evidence for neutrino emission from the novae considered in this analysis and set upper limits for all gamma-ray detected novae.

Keywords: novae; high energy astrophysics; neutrino astronomy; neutrino telescopes
Formation of Vitreous Salt Hydrates Under Conditions Relevant to Europa

Technologies are being developed to enable a robotic spacecraft to directly access Europa's ocean by penetrating its kilometers-thick ice crust. Until such time comes, however, our ability to characterize it will be limited to observations of its expression on the surface. Further, the ability to place meaningful constraints on the composition of the source brines will depend on our understanding of the chemistry associated with their freezing and emplacement. Among the body of research focused on improving this understanding, recent laboratory studies have shown that Mg-bearing salts, previously proposed as constituents of Europa's surface, have a propensity to form vitreous hydrates when flash frozen from their parent brines. The possibility that such vitreous species could form on Europa is important as their presence will be a confounding factor in their detection and identification of the underlying salt hydrates. Further, since glass formation can protect biological molecules and even microorganisms from damage caused by crystallization, they may prove to be important targets of astrobiological interest. This work explores the conditions under which vitreous salt hydrates form in order to better assess their potential for forming on Europa. Specifically, solutions of Mg- and Na-bearing salts were frozen over a range of freezing rates and interrogated with Raman spectroscopy to determine whether vitreous or crystalline species (including hydration state) formed. These results show that vitreous salt hydrates can form at freezing rates as low as ~10 K minute-1, thus expanding their potential for occurrence on Europa beyond extreme flash-freezing scenarios such as plume deposition.

Keywords: europa; astrochemistry; experimental techniques; high resolution spectroscopy; planetary science; surface processes
Evidence for Spatially Distinct Galactic Dust Populations

We present an implementation of a Bayesian mixture model using Hamiltonian Monte Carlo techniques to search for the spatial separation of Galactic dust populations. Utilizing intensity measurements from the Planck High Frequency Instrument, we apply this model to high-latitude Galactic dust emission. Our analysis reveals a strong preference for a spatially varying two-population dust model over a one-population dust model, when the latter must capture the total variance in the sky. Each dust population is well characterized by a single-component spectral energy distribution (SED) and accommodates small variations. These populations could signify two distinct components or may originate from a one-component model with different temperatures resulting in different SED scalings. While no spatial information is built into the likelihood, our investigation unveils large-scale spatially coherent structures with high significance, pointing to a physical origin for the observed spatial variation. These results are robust to our choice of likelihood and input data. Furthermore, this spatially varying two-population model is the most favored from Bayesian evidence calculations. Incorporating IRAS 100 μm to constrain the Wein side of the blackbody function, we find the dust populations differ at the 2.5σ level in the spectral index (β d ) versus temperature (T d ) plane. The presence of multiple dust populations has implications for component separation techniques frequently employed in the recovery of the cosmic microwave background.

Keywords: diffuse interstellar clouds; interstellar dust; interstellar medium
Damping of Oscillations in Red Giants by Resonant Mode Coupling

Asteroseismic studies of red giants generally assume that the oscillation modes can be treated as linear perturbations to the background star. However, observations by the Kepler mission show that the oscillation amplitudes increase dramatically as stars ascend the red giant branch. The importance of nonlinear effects should therefore be assessed. In previous work, we found that mixed modes in red giants are unstable to nonlinear three-wave interactions over a broad range of stellar mass and evolutionary state. Here we solve the amplitude equations that describe the mode dynamics for large networks of nonlinearly coupled modes. The networks consist of stochastically driven parent modes coupled to resonant secondary modes (daughters, granddaughters, etc.). We find that nonlinear interactions can lower the energy of gravity-dominated mixed modes by ≳80% compared to linear theory. However, they have only a mild influence on the energy of pressure-dominated mixed modes. Expressed in terms of the dipole-mode visibility V2, i.e., the summed amplitudes of dipole modes relative to radial modes, we find that V2 can be suppressed by 50%-80% relative to the linear value for highly evolved red giants whose frequency of maximum power ${\nu }_{\max }\lesssim 100\,\mu \mathrm{Hz}$ . However, for less evolved red giants with $150\lesssim {\nu }_{\max }\lesssim 200\,\mu \mathrm{Hz}$ , V2 is suppressed by only 10%-20%. We conclude that resonant mode coupling can have a potentially detectable effect on oscillations at ${\nu }_{\max }\lesssim 100\,\mu \mathrm{Hz}$ but it cannot account for the population of red giants that exhibit dipole modes with unusually small amplitudes at high ${\nu }_{\max }$ .

Keywords: asteroseismology; stellar oscillations; internal waves; astrophysical fluid dynamics
Exploring Neutral Hydrogen in Radio MOlecular Hydrogen Emission Galaxies (MOHEGs) and Prospects with the SKA

Empirical studies of cold gas content are essential for comprehending the star formation activities and evolution in galaxies. However, it is not straightforward to understand these processes because they depend on various physical properties of the interstellar medium. Massive Faranoff–Riley I/II type radio galaxies rich in molecular hydrogen with lower star formation activities are known as radio molecular hydrogen emission galaxies (MOHEGs). We present a study of neutral hydrogen-gas-associated radio MOHEGs at redshifts <0.2 probed via the H I 21 cm absorption line. Neutral hydrogen is detected in 70% of these galaxies, which are located at a distance of 8–120 kpc from the neighboring galaxies. These galaxies show a scarcity of H I gas as compared to merging galaxies at similar redshifts. We found no strong correlation between N(H I), NH, and the galaxy properties, regardless of whether the H I is assumed to be cold or warm, indicating that the atomic gas probably plays no important role in star formation. The relation between the total hydrogen gas surface density and the star formation surface density deviates from the standard Kennicutt–Schmidt law. Our study highlights the importance of H I studies and offers insights into the role of atomic and molecular hydrogen gas in explaining the properties of these galaxies. In the upcoming H I 21 cm absorption surveys with next-generation radio telescopes such as the Square Kilometre Array and pathfinder instruments, it may be possible to provide better constraints for these correlations.

Keywords: star formation; fanaroff-riley radio galaxies
VeSPA: The SuperWASP Variable Star Photometry Archive

We present the first results from the SuperWASP Variable Stars (SVS) citizen science project. The photometry archive of the Wide Angle Search for Planets has previously been searched for periodic variations and the results of this search formed the basis of the SVS project on the Zooniverse. The SVS project asks volunteers to visually inspect light curve plots and categorize each one according to a broad classification scheme. Results from the first two years of SVS have now been published online as the SuperWASP Variable Star Photometry Archive (VeSPA). The archive can be browsed online, downloaded in full, or queried, filtered, and sorted to export a refined set of results. An interactive light curve viewer also allows any light curve to be folded at a user-defined period. Analysis of citizen science results and development of VeSPA features are both ongoing. Updated results will be published every six months.

Keywords: variable stars; catalogs; surveys; eclipsing binary stars; pulsating variable stars
Exploring the Origin of Moving Groups and Diagonal Ridges by Simulations of Stellar Orbits and Birthplaces

The present paper is the culmination of a series aimed at contributing to the understanding of the kinematic structures of the solar neighborhood (SN), explaining the origin of the Local Arm, and relating the moving groups with the spiral-arms resonances in the disk. With a model for the Galactic potential, with the Sun inside the spiral corotation resonance (CR), we integrate the 2D orbits of test particles distributed in birthplaces along the main spiral arms, the Local Arm, and in the axisymmetric disk. A comparison of the resulting U-V plane of the SN with that provided by Gaia DR2 confirms our previous conclusion that the moving groups of Coma Berenices, Pleiades, and Hyades are associated with the CR, and that the Hercules stream is formed by the bulk of high-order inner Lindblad resonances. The kinematic structures result from stellar orbits trapped by the spiral resonances in a timespan of ∼1 Gyr, indicating the long-lived nature of the spiral structure and challenging recent arguments in favor of short-lived structures originated from incomplete phase mixing in the Galactic disk. As a byproduct, our simulations give some insight into the birthplaces of the stars presently located in the SN; the majority of stars of the main moving groups and the Hercules stream were likely born in the Local Arm, while stars of the Sirius group possibly originated from the outer segment of the Sagittarius-Carina arm. We also propose the spiral resonances as the dynamical origin for the diagonal ridges in the Galactic distribution of rotation velocities.

Keywords: milky way disk; milky way dynamics; milky way evolution; stellar kinematics; spiral arms; solar neighborhood
Spitzer Variability Properties of Low-gravity L Dwarfs

We present Spitzer Space Telescope variability monitoring observations of three low-gravity L dwarfs with previous detections of variability in the near-IR: 2MASS J0045+16, 2MASS J0501-00, and 2MASS J1425-36. We detect significant periodic variability in two of our targets, 2MASS J0045+16 and 2MASS J0501-00. We do not detect variability in 2MASS J1425-36. Combining our new rotation periods with rotational velocities, we calculate inclination angles of 22° ± 1°, ${60}_{-8}^{+{13}^{^\circ }}$ , and ${52}_{-13}^{+{19}^{^\circ }}$ for 2MASS J0045+16, 2MASS J0501-00, and 2MASS J1425-36, respectively. Our three new objects are consistent with the tentative relations between inclination, amplitude, and color anomaly previously reported. Objects with the highest variability amplitudes are inclined equator on, while the maximum observed amplitude decreases as the inclination angle decreases. We also find a correlation between the inclination angle and ${(J-K)}_{2\mathrm{MASS}}$ color anomaly for the sample of objects with measured inclinations. Compiling the entire sample of brown dwarfs with Spitzer variability detections, we find no enhancement in amplitude for young, early-L dwarfs compared to the field dwarf population. We find a possible enhancement in amplitude of low-gravity late-L dwarfs at 4.5 μm. We do not find a correlation between amplitude ratio and spectral type for field dwarfs or for the young population. Finally, we compile the rotation periods of a large sample of brown dwarfs with ages 1 Myr-1 Gyr and compare the rotation rates predicted by evolutionary models assuming angular momentum conservation. We find that the rotation rates of the current sample of brown dwarfs fall within the expected range set by evolutionary models and breakup limits.

Keywords: brown dwarfs; atmospheric variability; l dwarfs
Seeking Self-regulating Simulations of Idealized Milky Way-like Galaxies

Precipitation is potentially a mechanism through which the circumgalactic medium (CGM) can regulate a galaxy's star formation. Here, we present idealized simulations of isolated Milky Way-like galaxies intended to examine the ability of galaxies to self-regulate their star formation, in particular via precipitation. We also examine the impact of rotation in the CGM. Using six simulations, we explore variations in the initial CGM t cool/t ff ratio and rotation profile. Those variations affect the amount of gas accretion and star formation within the galactic disk. To encourage this accretion and better study its dependence on CGM structure, we gradually increase the efficiency of stellar feedback during the first half of our simulations. Yet despite this gradual increase, the resulting outflows quickly evacuate large, hot cavities within the CGM and even beyond r 200. Some of the CGM gas avoids interacting with the cavities and is able to feed the disk along its midplane, but the cooling of feedback-heated gas far from the midplane is too slow to supply the disk with additional gas. Our simulations illustrate the importance of physical mechanisms in the outer CGM and IGM for star formation regulation in Milky Way-scale halos.

Keywords: stellar feedback; galaxy processes; galaxy evolution; circumgalactic medium; hydrodynamical simulations
A Wave-corrected Assessment of the Local Midplane

As the number of known Galactic structures mounts thanks to the Gaia Space Telescope, it is now pertinent to study methods for disentangling structures occupying the same regions of the Milky Way. Indeed, understanding the precise form of each individual structure and the interactions between structures may aid in understanding their origins and chronology. Moreover, accounting for known structures allows one to probe still finer Galactic structure. In order to demonstrate this, we have developed an odd low-pass filter (OLPF), which removes smaller, odd-parity structures like the vertical waves, and use the filtered data to examine the location of the Galaxy's midplane. We find that the radial wave identified by Xu et al. continues inward to at least the Sun's location, with an amplitude that decreases toward the inner, denser parts of the disk, consistent with a simple, qualitative simulation. Additionally, we employ the OLPF results to determine the solar offset, z ⊙, with smaller structures filtered out. We find that z ⊙ = 34.2 ± 0.3 pc.

Keywords: galactic archaeology; milky way galaxy physics; milky way disk
MIDIS: JWST NIRCam and MIRI Unveil the Stellar Population Properties of Lyα Emitters and Lyman-break Galaxies at z ≃ 3–7

We study the stellar population properties of 182 spectroscopically confirmed (MUSE/VLT) Lyα emitters (LAEs) and 450 photometrically selected Lyman-break galaxies (LBGs) at z = 2.8–6.7 in the Hubble Extreme Deep Field. Leveraging the combined power of Hubble Space Telescope and JWST NIRCam and MIRI observations, we analyze their rest-frame UV-through-near-IR spectral energy distributions, with MIRI playing a crucial role in robustly assessing the LAEs' stellar masses and ages. Our LAEs are low-mass objects $({{\rm{log}}}_{10}({M}_{\star }/{M}_{\odot })\simeq 7.5)$ with little or no dust extinction (E(B ‑ V) ≃ 0.1) and a blue UV continuum slope (β ≃ ‑2.2). While 75% of our LAEs are young (<100 Myr), the remaining 25% have significantly older stellar populations (≥100 Myr). These old LAEs are statistically more massive, less extinct, and have lower specific star formation rate than young LAEs. Besides, they populate the plane of M ⋆ versus star formation rate along the main sequence of star-forming galaxies, while young LAEs populate the starburst region. The comparison between the LAEs' properties and those of a stellar-mass-matched sample of LBGs shows no statistical difference between these objects, except for the LBGs' redder UV continuum slope and marginally larger E(B ‑ V) values. Interestingly, 48% of the LBGs have ages <10 Myr and are classified as starbursts, but lack detectable Lyα emission. This is likely due to H I resonant scattering and/or dust-selective extinction. Overall, we find that JWST observations are crucial in determining the properties of LAEs and shedding light on their comparison with LBGs.

Keywords: lyman-alpha galaxies; lyman-break galaxies; galaxy evolution; infrared telescopes
Assessment of Astronomical Images Using Combined Machine-learning Models

We present a two-component machine-learning-based approach for classifying astronomical images by data quality via an examination of sources detected in the images and image pixel values from representative sources within those images. The first component, which uses a clustering algorithm, creates a proper and small fraction of the image pixels to determine the quality of the observation. The representative images (and associated tables) are ∼800 times smaller than the original images, significantly reducing the time required to train our algorithm. The useful information in the images is preserved, permitting them to be classified into different categories, but the required storage is reduced. The second component, which is a deep neural network model, classifies the representative images. Using ground-based telescope imaging data, we demonstrate that the method can be used to separate "usable" images from those that present some problems for scientific projects -- such as images that were taken in suboptimal conditions. This method uses two different data sets as input to a deep model and provides better performance than if we only used the images' pixel information. The method may be used in cases where large and complex data sets should be examined using deep models. Our automated classification approach achieves 97% agreement when compared to classification generated via manual image inspection. We compare our method with traditional results and show that the method improves the results by about 10%, and also presents more comprehensive outcomes.

Keywords: astronomy data analysis; convolutional neural networks; neural networks; astronomy data modeling; astronomy data visualization