adsabs/SciX_UAT_keywords huggingface dataset:
A Subsolar Metallicity on the Ultra-short-period Planet HIP 65Ab

Studying and understanding the physical and chemical processes that govern hot Jupiters gives us insights on the formation of these giant planets. Having a constraint on the molecular composition of their atmosphere can help us pinpoint their evolution timeline. Namely, the metal enrichment and carbon-to-oxygen ratio can give us information about where in the protoplanetary disk a giant planet may have accreted its envelope, and, subsequently, indicate if it went through migration. Here we present the first analysis of the atmosphere of the hot Jupiter HIP 65Ab. Using near-infrared high-resolution observations from the IGRINS spectrograph, we detect H2O and CO absorption in the dayside atmosphere of HIP 65Ab. Using a high-resolution retrieval framework, we find a CO abundance of log(CO) = $-{3.85}_{-0.36}^{+0.33}$ , which is slightly underabundant with expectation from solar composition models. We also recover a low-water abundance of log(H2O) = ‑4.42 ± 0.18, depleted by 1 order of magnitude relative to a solar-like composition. Upper limits on the abundance of all other relevant major carbon- and oxygen-bearing molecules are also obtained. Overall, our results are consistent with a sub-stellar metallicity but slightly elevated C/O. Such a composition may indicate that HIP 65Ab accreted its envelope from beyond the water snowline and underwent a disk-free migration to its current location. Alternatively, some of the oxygen on HIP 65Ab could be condensed out of the atmosphere, in which case the observed gas-phase abundances would not reflect the true bulk envelope composition.

Keywords: exoplanet atmospheres; exoplanet atmospheric composition; high resolution spectroscopy; exoplanets; hot jupiters; exoplanet astronomy; observational astronomy
Magnetic Reconnection in the Wakes of Cosmic Strings

The motion of cosmic strings in the universe leads to the generation of wakes behind them. We study magnetized wakes of cosmic strings moving in the postrecombination plasma. We show that magnetic reconnection can occur in the postshock region. Since the width of the cosmic-string wake is very small, the reconnection occurs over a very short length scale. The reconnection leads to a large amount of kinetic energy being released in the postshock region of the cosmic-string wake. This enhances the kinetic energy released during the reconnection. We make a rudimentary estimate of the kinetic energy released by the magnetic reconnection in cosmic-string wakes and show that it can account for low-energy gamma-ray bursts in the postrecombination era.

Keywords: cosmic magnetic fields theory; gamma-ray bursts
Modeling the Hα and He 10830 Transmission Spectrum of WASP-52b

Escaping atmosphere has been detected by the excess absorption of Lyα, Hα and He triplet (λ10830) lines. Simultaneously modeling the absorption of the Hα and He λ10830 lines can provide useful constraints about the exoplanetary atmosphere. In this paper, we use a hydrodynamic model combined with a non-local thermodynamic model and a new Monte Carlo simulation model to obtain the H(2) and He(23 S) populations. The Monte Carlo simulations of Lyα radiative transfer are performed with assumptions of a spherical stellar Lyα radiation and a spherical planetary atmosphere, for the first time, to calculate the Lyα mean intensity distribution inside the planetary atmosphere, necessary in estimating the H(2) population. We model the transmission spectra of the Hα and He λ10830 lines simultaneously in hot Jupiter WASP-52b. We find that models with many different H/He ratios can reproduce the Hα observations well if the host star has (1) a high X-ray and extreme-ultraviolet (XUV) flux (F XUV) and a relatively low X-ray fraction in XUV radiation (β m ) or (2) a low F XUV and a high β m . The simulations of the He λ10830 triplet suggest that a high H/He ratio (~98/2) is required to fit the observation. The models that fit both lines well confine F XUV to be about 0.5 times the fiducial value and β m to have a value around 0.3. The models also suggest that hydrogen and helium originate from the escaping atmosphere, and the mass-loss rate is about 2.8 × 1011 g s-1.

Keywords: exoplanet atmospheres; hydrodynamical simulations; radiative transfer simulations
A Linear Relation between the Color Stretch s BV and the Rising Color Slope {s}_{0}({*) }(B-V) of Type Ia Supernovae

Using data from the Complete Nearby (redshift z host < 0.02) sample of Type Ia Supernovae (CNIa0.02), we find a linear relation between two parameters derived from the B - V color curves of Type Ia supernovae: the color stretch s BV and the rising color slope ${s}_{0}^{* }(B-V)$ after the peak, and this relation applies to the full range of s BV . The s BV parameter is known to be tightly correlated with the peak luminosity, especially for fast decliners (dim Type Ia supernovae), and the luminosity correlation with s BV is markedly better than with the classic light-curve width parameters such as Δm 15(B). Thus, our new linear relation can be used to infer peak luminosity from ${s}_{0}^{* }$ . Unlike s BV (or Δm 15(B)), the measurement of ${s}_{0}^{* }(B-V)$ does not rely on a well-determined time of light-curve peak or color maximum, making it less demanding on the light-curve coverage than past approaches.

Keywords: type ia supernovae; supernovae; time series analysis; light curves
The Effect of a Strong Pressure Bump in the Sun's Natal Disk: Terrestrial Planet Formation via Planetesimal Accretion Rather than Pebble Accretion

Mass-independent isotopic anomalies of carbonaceous and noncarbonaceous meteorites show a clear dichotomy suggesting an efficient separation of the inner and outer solar system. Observations show that ring-like structures in the distribution of millimeter-sized pebbles in protoplanetary disks are common. These structures are often associated with drifting pebbles being trapped by local pressure maxima in the gas disk. Similar structures may also have existed in the Sun's natal disk, which could naturally explain the meteorite/planetary isotopic dichotomy. Here, we test the effects of a strong pressure bump in the outer disk (e.g., ~5 au) on the formation of the inner solar system. We model dust coagulation and evolution, planetesimal formation, as well as embryo growth via planetesimal and pebble accretion. Our results show that terrestrial embryos formed via planetesimal accretion rather than pebble accretion. In our model, the radial drift of pebbles fosters planetesimal formation. However, once a pressure bump forms, pebbles in the inner disk are lost via drift before they can be efficiently accreted by embryos growing at ⪆1 au. Embryos inside ~0.5-1.0 au grow relatively faster and can accrete pebbles more efficiently. However, these same embryos grow to larger masses so they should migrate inwards substantially, which is inconsistent with the current solar system. Therefore, terrestrial planets most likely accreted from giant impacts of Moon to roughly Mars-mass planetary embryos formed around ⪆1.0 au. Finally, our simulations produce a steep radial mass distribution of planetesimals in the terrestrial region, which is qualitatively aligned with formation models suggesting that the asteroid belt was born low mass.

Keywords: solar system terrestrial planets; protoplanetary disks; planetesimals
Measurement of n- and l-resolved State-selective Charge Exchange in Ar8+ Collision with He

The state-resolved capture cross sections for principal n and orbital angular momentum l play an important role in modeling soft X-ray emissions induced by charge exchange for many astrophysical environments. However, the empirical and semiclassical theories used to produce these data of n- and l-resolved state-selective capture have not been well tested. Using the cold target recoil ion momentum spectroscopy apparatus at Fudan University, we perform a series of measurements of Ar8+ ion charge exchange with He in the collision energy range from 1.4 to 20 keV u-1. We find that electrons are mainly captured in the n = 4 state of Ar7+ ions. This agrees with the prediction of the scaling law for n capture. Moreover, the relative cross sections are reported for 4s-, 4p-, 4d-, and 4f-resolved state-selective capture. The often used analytical l distributions in the astrophysical literature are evaluated by comparing to the measurements.

Keywords: atomic data benchmarking; atomic physics; collision physics; charge exchange recombination
Sunspot Simulations: Penumbra Formation and the Fluting Instability

The fluting instability has been suggested as the driver of the subsurface structure of sunspot flux tubes. We conducted a series of numerical experiments where we used flux tubes with different initial curvatures to study the effect of the fluting instability on the subsurface structure of spots. We used the MURaM code, which has previously been used to simulate complete sunspots, to first compute four sunspots in the slab geometry and then two complete circular spots of opposite polarities. We find that the curvature of a flux tube indeed determines the degree of fluting the flux tube will undergo—the more curved a flux tube is, the more fluted it becomes. In addition, sunspots with strong curvature have strong horizontal fields at the surface and therefore readily form penumbral filaments. The fluted sunspots eventually break up from below, with lightbridges appearing at the surface several hours after fluting commences.

Keywords: sunspots; starspots; solar physics; radiative magnetohydrodynamics; solar interior; stellar interiors
Galactopause Formation and Gas Precipitation during Strong Galactic Outflows

Using X-ray constrained β-models for the radial distribution of gas in the outskirts of galaxies, we analyze the termination of galactic winds and the formation and evolution of halo clouds by thermal instability. At low mass-loss rates ( ${\dot{M}}_{w}$ ) galactic winds are trapped within the halo, but they burst into the intergalactic medium during intermittent strong outflows with ${\dot{M}}_{w}\gt 10\,{M}_{\odot }\,{{\rm{yr}}}^{-1}$ . We develop analytic models of halo clouds as they cool radiatively over condensation timescales ${t}_{{\rm{c}}}\approx {(390\mathrm{Myr})({T}_{6}/{n}_{-4})(Z/{Z}_{\odot })}^{-1}$ for hydrogen number densities ${n}_{{\rm{H}}}\approx ({10}^{-4}\,{\mathrm{cm}}^{-3}){n}_{-4}$ , gas temperatures T ≈ (106 K)T6, and metallicities (Z/Z⊙). Halo gas can form kiloparsec-scale clouds out to galactocentric distances r ≈ 30-65 kpc, where efficient radiative cooling from 106 K down to T ≈ 104-5 K occurs at Z ≥ 0.3 Z⊙ on timescales less than 1 Gyr. After condensing to column densities NH ≥ 4 × 1016 cm-2, these clouds lose hydrostatic pressure support and fall inward on dynamical timescales of ∼200 Myr. Our baseline analysis will be followed by numerical calculations to understand the governing principles of halo cloud formation and transport of gas to the galactic disk.

Keywords: galactic winds; high-velocity clouds; interstellar medium
Rings, Shells, and Arc Structures Around B[e] Supergiants. I. Classical Tools of Nonlinear Hydrodynamics

Structures in circumstellar matter reflect both fast processes and quasi-equilibrium states. A geometrical diversity of emitting circumstellar matter is observed around evolved massive stars, in particular around B[e] supergiants. We recapitulate classical analytical tools of linear and nonlinear potential theory, such as Cole–Hopf transformation and Grad–Shafranov theory, and develop them further to explain the occurrence of the circumstellar matter structures and their dynamics. We use potential theory to formulate the nonlinear hydrodynamical equations and test dilatations of the quasi-equilibrium initial conditions. We find that a wide range of flow patterns can basically be generated and the timescales can switch, based on initial conditions, and lead to eruptive processes, reinforcing that the nonlinear fluid environment includes both quasi-stationary structures and fast processes like finite-time singularities. Some constraints and imposed symmetries can lead to Keplerian orbits, while other constraints can deliver quasi-Keplerian ones. The threshold is given by a characteristic density at the stellar surface.

Keywords: hydrodynamics; analytical mathematics; stellar winds; circumstellar matter
Three-dimensional Magnetohydrodynamic Simulations of Periodic Variations of Ganymede's Footprint

Alfvénic power is generated through the interaction between the mini-magnetosphere of Ganymede and the corotating flow of the Jovian plasma, contributing to the formation of the Ganymede auroral footprint at Jupiter's ionosphere. Using a three-dimensional, high-resolution global magnetohydrodynamic model of the Ganymede magnetosphere, we investigate the temporal variations of the Alfvénic power generated in the mini-magnetosphere of the moon under steady-state upstream conditions. Results show that (1) the Alfvénic power caused by the intermittent magnetic reconnections and the Kelvin–Helmholtz instabilities is quasiperiodic, varying over time with the periods about 71–333 s, which are consistent with the 100 s timescale periodicities of the Ganymede footprint's emitted power; and (2) the magnitude of the Alfvénic power is smaller when Ganymede is inside the Jovian plasma sheet where the B y component is smaller, and larger when the moon is outside the plasma sheet where the B y component is larger.

Keywords: alfven waves; ganymede; magnetohydrodynamical simulations; magnetohydrodynamics
Superposed Epoch Analysis of Galactic Cosmic Rays and Solar Wind based on ACE Observations During Two Recent Solar Minima

Based on galactic cosmic ray (GCR) and plasma observations from the ACE spacecraft, in this work, we analyze the relation between the GCR counts and the solar wind parameters during two recent two solar minima (for the years 2007.0-2009.0, and 2016.5-2018.5) by means of the superposed epoch analysis (SEA) method. The results indicate that GCRs are strongly modulated by the co-rotating interaction regions (CIRs) in the solar wind, and that the occurrences of stream interfaces (SIs) between fast and slow solar wind are correlated with a depression in GCR counts. The so-called "snow plow" effect of GCR variation prior to SI crossing appears during the first solar minimum, and the GCR counts decrease after the crossing, corresponding to a sudden drop in the diffusion coefficient at the SIs. The gradient of GCR counts shows that the transport efficiency of GCRs is low (high), relative to slow (fast) solar wind. However, during the second solar minimum, we see a completely opposite scenario; the "snow plow" effect is not observed, and GCR transport becomes faster in slow solar wind, and slower in fast solar wind. In addition, heliospheric current-sheet crossings also correlate with GCR counts. Particles drift along the current sheet, then accumulate in a pileup structure, where diffusion and drift effects may be balanced. It is found that the drift effect rivals the diffusion and convection on the GCR transport at 1 au during the two solar minima.

Keywords: galactic cosmic rays; solar wind; interplanetary turbulence
Astromers in the Radioactive Decay of r-process Nuclei

Certain nuclear isomers are well known to affect nucleosynthesis with important observable consequences (e.g., 26Al and 180Ta). We study the impact of nuclear isomers in the context of rapid neutron capture process (r-process) nucleosynthesis. We demonstrate that nuclear isomers are dynamically populated in the r process and that some are populated far from thermal equilibrium; this makes them astrophysical isomers, or "astromers." We compute thermally mediated transition rates between long-lived isomers and the corresponding ground states in neutron-rich nuclei. We calculate the temperature-dependent β-decay feeding factors, which represent the fraction of material going to each of the isomer and ground state daughter species from the β-decay parent species. We simulate nucleosynthesis following the decay of a solar-like r-process composition and include as separate species nuclear excited states with measured terrestrial half-lives greater than 100 μs. We introduce a new metric to identify those astromers most likely to be influential and summarize them in a table. Notable entries include many second peak nuclei (e.g., the Te isotopic chain) and previously overlooked isomers in stable nuclei (e.g., 119Sn, 131Xe, and 195Pt). Finally, we comment on the capacity of isomer production to alter radioactive heating in an r-process environment.

Keywords: nuclear astrophysics; r-process; nuclear physics
Evidence of Extended Dust and Feedback around z ≈ 1 Quiescent Galaxies via Millimeter Observations

We use public data from the South Pole Telescope (SPT) and Atacama Cosmology Telescope (ACT) to measure the radial profiles of the thermal Sunyaev-Zel'dovich (tSZ) effect and dust emission around massive quiescent galaxies at z ≈ 1. Using survey data from the Dark Energy Survey and Wide-Field Infrared Survey Explorer, we selected 387,627 quiescent galaxies within the ACT field, with a mean stellar ${\mathrm{log}}_{10}({M}_{\star }/{M}_{\odot })$ of 11.40. A subset of 94,452 galaxies, with a mean stellar ${\mathrm{log}}_{10}({M}_{\star }/{M}_{\odot })$ of 11.36, are also covered by SPT. In $0\buildrel{\,\prime}\over{.} \,5$ bins around these galaxies, we detect the tSZ profile at levels up to 11σ, and dust profile up to 20σ. Both profiles are extended, and the dust profile slope at large radii is consistent with galaxy clustering. We analyze the thermal energy and dust mass versus stellar mass via integration within $R=2\buildrel{\,\prime}\over{.} \,0$ circular apertures and fit them with a forward-modeled power law to correct for our photometric stellar mass uncertainties. At the mean log stellar mass of our Overlap and Wide-Area Samples, respectively, we extract thermal energies from the tSZ of ${E}_{\mathrm{pk}}={6.45}_{-1.52}^{+1.67}\times {10}^{60}\,\mathrm{erg}$ and ${8.20}_{-0.52}^{+0.52}\times {10}^{60}\,\mathrm{erg},$ most consistent with moderate to high levels of active galactic nucleus feedback acting upon the circumgalactic medium. Dust masses at the mean log stellar mass are ${M}_{{\rm{d}},\mathrm{pk}}={6.23}_{-0.67}^{+0.67}\times {10}^{8}\,{M}_{\odot }$ and ${6.76}_{-0.56}^{+0.56}\times {10}^{8}\,{M}_{\odot },$ respectively, and we find a greater than linear dust-to-stellar mass relation, which indicates that the more-massive galaxies in our study retain more dust. Our work highlights the current capabilities of stacking millimeter data around individual galaxies and their potential for future use.

Keywords: cosmic background radiation; galaxy evolution; intergalactic medium; large-scale structure of the universe; sunyaev-zeldovich effect; quasars; interstellar dust
Vertical Distribution of Cyclopropenylidene and Propadiene in the Atmosphere of Titan

Titan's atmosphere is a natural laboratory for exploring the photochemical synthesis of organic molecules. Significant recent advances in the study of the atmosphere of Titan include: (a) detection of C3 molecules: C3H6, CH2CCH2, c-C3H2, and (b) retrieval of C6H6, which is formed primarily via C3 chemistry, from Cassini Ultraviolet Imaging Spectrograph data. The detection of c-C3H2 is of particular significance as ring molecules are of great astrobiological importance. Using the Caltech/JPL KINETICS code, along with the best available photochemical rate coefficients and parameterized vertical transport, we are able to account for the recent observations. It is significant that ion chemistry, reminiscent of that in the interstellar medium, plays a major role in the production of c-C3H2 above 1000 km.

Keywords: titan; planetary atmospheres; atmospheric composition
Solar Active Region Coronal Jets. III. Hidden-onset Jets

Solar quiet- and coronal-hole region coronal jets frequently clearly originate from erupting minifilaments, but active-region jets often lack an obvious erupting-minifilament source. We observe a coronal-jet-productive active region (AR), AR 12824, over 2021 May 22 0-8 UT, primarily using Solar Dynamics Observatory (SDO) Atmospheric Imaging Array (AIA) EUV images and SDO/Helioseismic and Magnetic Imager magnetograms. Jets were concentrated in two locations in the AR: on the south side and on the northwest side of the AR's lone large sunspot. The south-location jets are oriented so that we have a clear view of the jets' origin low in the atmosphere: their source is clearly minifilaments erupting from locations showing magnetic flux changes/cancelations. After erupting a projected distance ≲5″ away from their origin site, the minifilaments erupt outward onto far-reaching field as part of the jet's spire, quickly losing their minifilament character. In contrast, the northwest-location jets show no clear erupting minifilament, but the source site of those jets are obscured along our line of sight by absorbing chromospheric material. EUV and magnetic data indicate that the likely source sites were ≳15″ from where the we first see the jet spire; thus, an erupting minifilament would likely lose its minifilament character before we first see the spire. We conclude that such AR jets could work like non-AR jets, but the erupting-minifilament jet source is often hidden by obscuring material. Another factor is that magnetic eruptions making some AR jets carry only a harder-to-detect comparatively thin (~1″-2″) minifilament "strand."

Keywords: solar filament eruptions; solar extreme ultraviolet emission; solar active regions; solar active region magnetic fields
Validation of Elemental and Isotopic Abundances in Late-M Spectral Types with the Benchmark HIP 55507 AB System

M dwarfs are common host stars to exoplanets but often lack atmospheric abundance measurements. Late-M dwarfs are also good analogs to the youngest substellar companions, which share similar T eff ∼ 2300–2800 K. We present atmospheric analyses for the M7.5 companion HIP 55507 B and its K6V primary star with Keck/KPIC high-resolution (R ∼ 35,000) K-band spectroscopy. First, by including KPIC relative radial velocities between the primary and secondary in the orbit fit, we improve the dynamical mass precision by 60% and find ${M}_{B}={88.0}_{-3.2}^{+3.4}\,{M}_{\mathrm{Jup}}$ , putting HIP 55507 B above the stellar–substellar boundary. We also find that HIP 55507 B orbits its K6V primary star with $a={38}_{-3}^{+4}$ au and e = 0.40 ± 0.04. From atmospheric retrievals of HIP 55507 B, we measure [C/H] = 0.24 ± 0.13, [O/H] = 0.15 ± 0.13, and C/O = 0.67 ± 0.04. Moreover, we strongly detect 13CO (7.8σ significance) and tentatively detect ${{\rm{H}}}_{2}^{18}{\rm{O}}$ (3.7σ significance) in the companion's atmosphere and measure ${}^{12}\mathrm{CO}{/}^{13}\mathrm{CO}={98}_{-22}^{+28}$ and ${{\rm{H}}}_{2}^{16}{\rm{O}}/{{\rm{H}}}_{2}^{18}{\rm{O}}={240}_{-80}^{+145}$ after accounting for systematic errors. From a simplified retrieval analysis of HIP 55507 A, we measure ${}^{12}\mathrm{CO}{/}^{13}\mathrm{CO}={79}_{-16}^{+21}$ and ${{\rm{C}}}^{16}{\rm{O}}/{{\rm{C}}}^{18}{\rm{O}}={288}_{-70}^{+125}$ for the primary star. These results demonstrate that HIP 55507 A and B have consistent 12C/13C and 16O/18O to the <1σ level, as expected for a chemically homogeneous binary system. Given the similar flux ratios and separations between HIP 55507 AB and systems with young substellar companions, our results open the door to systematically measuring 13CO and ${{\rm{H}}}_{2}^{18}{\rm{O}}$ abundances in the atmospheres of substellar or even planetary-mass companions with similar spectral types.

Keywords: atmospheric composition; stellar atmospheres; isotopic abundances; radial velocity