adsabs/SciX_UAT_keywords huggingface dataset:
The Origin of Systems of Tightly Packed Inner Planets with Misaligned, Ultra-short-period Companions

Ultra-short-period planets provide a window into the inner edge of the parameter space occupied by planetary orbits. In one particularly intriguing class of multiplanet systems, the ultra-short-period planet is flanked by short-period companions, and the outer planets occupy a discernibly distinct dynamical state. In the observational database, this phenomenon is represented by a small number of stars hosting systems of tightly packed coplanar planets as well as an ultra-short-period planet, whose orbit is misaligned relative to the mutual plane of the former. In this work, we explore two different mechanisms that can produce an ultra-short-period planet that is misaligned with the rest of its compact planetary system: natural decoupling between the inner and outer system via the stellar quadrupole moment, and decoupling forced by an external companion with finely tuned orbital parameters. These two processes operate with different timescales, and can thus occur simultaneously. In this work, we use the K2-266 system as an illustrative example to elucidate the dynamics of these two processes, and highlight the types of constraints that may arise regarding the dynamical histories of systems hosting ultra-short-period planets.

Keywords: exoplanet dynamics; exoplanet evolution
Reduced Water Loss due to Photochemistry on Terrestrial Planets in the Runaway Greenhouse Phase around Pre-main-sequence M Dwarfs

Terrestrial planets currently in the habitable zone around M dwarfs are estimated to have been in runaway greenhouse conditions for up to ∼1 Gyr due to the long-term pre-main-sequence phase of M dwarfs. These planets likely lose a significant portion of water during the pre-main-sequence phase owing to H2O photolysis followed by hydrogen and oxygen loss to space. However, the effects of H2O reproduction reactions and UV shielding by chemical products that reduce photolysis-induced water loss have yet to be estimated. Here, we apply a 1D photochemical model to a H2O-dominated atmosphere of an Earth-like planet around a pre-main-sequence M dwarf to estimate these effects. We find that water loss is suppressed by efficient H2O reproduction reactions and by UV shielding due to O2. The water loss rate decreases by several to several hundred times compared to that in previous studies, with the assumption that the water loss rate is limited by stellar X-ray and extreme-ultraviolet flux or hydrogen diffusion through the atmosphere. Our results imply that terrestrial planets currently in the habitable zone around M dwarfs are more likely to retain surface water than previously estimated.

Keywords: exoplanet atmospheric evolution; exoplanet atmospheres; exoplanet evolution; habitable planets; planetary atmospheres; planetary science; astrobiology; water vapor; atmospheric evolution; m dwarf stars; solar-terrestrial interactions
Explanation of Heliospheric Energetic Neutral Atom Fluxes Observed by the Interstellar Boundary Explorer

Interstellar neutral atoms propagating into the heliosphere experience charge exchange with the supersonic solar wind (SW) plasma, generating ions that are picked up by the SW. These pickup ions (PUIs) constitute ~25% of the proton number density by the time they reach the heliospheric termination shock (HTS). Preferential acceleration of PUIs at the HTS leads to a suprathermal, kappa-like PUI distribution in the heliosheath, which may be further heated in the heliosheath by traveling shocks or pressure waves. In this study, we utilize a dynamic, 3D magnetohydrodynamic model of the heliosphere to show that dynamic heating of PUIs at the HTS and in the inner heliosheath (IHS), as well as a background source of energetic neutral atoms (ENAs) from outside the heliopause, can explain the heliospheric ENA signal observed by the Interstellar Boundary Explorer (IBEX) in the Voyager 2 direction. We show that the PUI heating process at the HTS is characterized by a polytropic index larger than 5/3, likely ranging between γ ~ 2.3 and 2.7, depending on the time in solar cycle 24 and SW conditions. The ENA fluxes at energies >1.5 keV show large-scale behavior in time with the solar cycle and SW dynamic pressure, whereas ENAs < 1.5 keV primarily exhibit random-like fluctuations associated with SW transients affecting the IHS. We find that ≲20% of the ENAs observed at ~0.5-6 keV come from other sources, likely from outside the heliopause as secondary ENAs. This study offers the first model replication of the intensity and evolution of IBEX-Hi ENA observations from the outer heliosphere.

Keywords: pickup ions; termination shock; heliosphere; heliosheath; ion-neutral reactions; interstellar medium; interplanetary particle acceleration
Thermophysical Modeling of 20 Themis Family Asteroids with WISE/NEOWISE Observations

Themis family is one of the largest and oldest asteroid populations in the main belt. Water ice may widely exist on the parent body (24) Themis. In this work, we employ the Advanced Thermophysical Model as well as midinfrared measurements from NASA's Wide-field Infrared Survey Explorer to explore thermal parameters of 20 Themis family members. Here we show that the average thermal inertia and geometric albedo are 39.5 ± 26.0 J m-2 s-1/2 K-1 and 0.067 ± 0.018, respectively. The family members have a relatively moderate roughness fraction on their surfaces. We find that the relatively low albedos of Themis members are consistent with the typical values of B-type and C-type asteroids. As mentioned, the Themis family bears a very low thermal inertia, which indicates a fine and mature regolith on their surfaces. The resemblance of thermal inertia and geometric albedo of Themis members may reveal their close connection in origin and evolution. In addition, we present the compared results of thermal parameters for several prominent families.

Keywords: asteroid belt; main belt asteroids
Catch Me if You Can: Biased Distribution of Lyα-emitting Galaxies according to the Viewing Direction

We report that Lyα-emitting galaxies (LAEs) may not faithfully trace the cosmic web of neutral hydrogen (H I), but their distribution is likely biased depending on the viewing direction. We calculate the cross-correlation function (CCF) between galaxies and Lyα forest transmission fluctuations on the near and far sides of the galaxies separately, for three galaxy samples at z ∼ 2: LAEs, [O III] emitters (O3Es), and continuum-selected galaxies. We find that only LAEs have anisotropic CCFs, with the near side one showing lower signals up to r = 3-4 h-1 comoving Mpc. This means that the average H I density on the near side of LAEs is lower than that on the far side by a factor of 2.1 under the fluctuating Gunn-Peterson approximation. Mock LAEs created by assigning Lyα equivalent width ( ${{EW}}_{{\rm{Ly}}\alpha }^{{\rm{obs}}}$ ) values to O3Es with an empirical relation also show similar, anisotropic CCFs if we use only objects with higher ${{EW}}_{{\rm{Ly}}\alpha }^{{\rm{obs}}}$ than a certain threshold. These results indicate that galaxies on the far side of a dense region are more difficult to be detected ("hidden") in Lyα because Lyα emission toward us is absorbed by dense neutral hydrogen. If the same region is viewed from a different direction, a different set of LAEs will be selected as if galaxies are playing hide-and-seek using H I gas. Care is needed when using LAEs to search for overdensities.

Keywords: intergalactic medium; galaxy evolution; large-scale structure of the universe; lyman alpha forest; lyman-alpha galaxies
HIPPI-2 Commissioned at MIRA

We have commissioned the High Precision Polarimetric Instrument 2 on the Monterey Institute for Research in Astronomy's 36 inch telescope at its Bernard M. Oliver Observing Station. The night-to-night precision on bright stars is measured as σ p = 7.1 ppm and e p = 1.7 ppm in $g^{\prime} ;$ its accuracy on high polarization standard stars is 1.2%, despite the instrument not being actively guided. This matches the best performance achieved on much larger telescopes, which we attribute to the excellent site conditions.

Keywords: polarimetry; astronomical instrumentation; polarimeters
Investigating Cold Dust Properties of 12 Nearby Dwarf Irregular Galaxies by Hierarchical Bayesian Spectral Energy Distribution Fitting

Combining infrared and submillimeter observations and applying a two-temperature modified blackbody (TMBB) model with a hierarchical Bayesian technique, we model the spectral energy distribution of 12 nearby dwarf irregular (dIrr) galaxies. We aim to probe potential submillimeter excess emission at 350, 500, and 850 μm and investigate the properties of cold dust parameters. Based on the TMBB model with cold dust emissivity index (βc) fixed to 2, one galaxy shows 500 μm excess emission and nine galaxies show excess at 850 μm (five of them still show 850 μm excess in the case of free βc). We find that the 850 μm excess emission is easily detected in the dIrr galaxies with low star formation activity. The 850 μm excess is more frequent and more prominent in dIrr galaxies with low molecular hydrogen gas mass fraction or low ratios between cold dust mass and gas mass. As galaxies evolve, the ratios between atomic hydrogen gas mass and stellar mass decrease and the 850 μm excess emission tends to decrease or even disappear. Our results suggest that the cold dust temperature may increase, as the dIrr galaxies have more intense star formation or richer metallicity. There is a weak anticorrelation between the cold dust-to-stellar mass ratio and the specific star formation rate for our galaxies.

Keywords: dwarf irregular galaxies; interstellar medium; interstellar dust; submillimeter astronomy
Insights into the Galactic Bulge Chemodynamical Properties from Gaia Data Release 3

We explore the chemodynamical properties of the Galaxy in the azimuthal velocity V ϕ and metallicity [Fe/H] space using red giant stars from Gaia Data Release 3. The row-normalized V ϕ –[Fe/H] maps form a coherent sequence from the bulge to the outer disk, clearly revealing the thin/thick disk and the Splash. The metal-rich stars display bar-like kinematics, while the metal-poor stars show dispersion-dominated kinematics. The intermediate-metallicity population (‑1 < [Fe/H]< ‑ 0.4) can be separated into two populations, one that is bar-like, i.e., dynamically cold ( ${\sigma }_{{V}_{R}}\sim 80$ km s‑1) and fast-rotating (V ϕ ≳ 100 km s‑1), and the Splash, which is dynamically hot ( ${\sigma }_{{V}_{R}}\sim 110$ km s‑1) and slow-rotating (V ϕ ≲ 100 km s‑1). We compare the observations in the bulge region with an Auriga simulation where the last major merger event occurred ∼10 Gyr ago: only stars born around the time of the merger reveal a Splash-like feature in the V ϕ –[Fe/H] space, suggesting that the Splash is likely merger-induced, predominantly made up of heated disk stars and the starburst associated with the last major merger. Since the Splash formed from the proto-disk, its lower metallicity limit coincides with that of the thick disk. The bar formed later from the dynamically hot disk with [Fe/H] > ‑ 1 dex, with the Splash not participating in the bar formation and growth. Moreover, with a set of isolated evolving N-body disk simulations, we confirm that a nonrotating classical bulge can be spun up by the bar and develop cylindrical rotation, consistent with the observations for the metal-poor stars.

Keywords: galactic bulge; galaxy bulges; milky way evolution
Measuring Elemental Abundances of JWST Target Stars for Exoplanet Characterization. I. FGK Stars

With the launch of the JWST, we will obtain more precise data for exoplanets than ever before. However, these data can only inform and revolutionize our understanding of exoplanets when placed in the larger context of planet-star formation. Therefore, gaining a deeper understanding of their host stars is equally important and synergistic with the upcoming JWST data. We present detailed chemical abundance profiles of 17 FGK stars that will be observed in exoplanet-focused Cycle 1 JWST observer programs. The elements analyzed (C, N, O, Na, Mg, Si, S, K, and Fe) were specifically chosen as being informative to the composition and formation of planets. Using archival high-resolution spectra from a variety of sources, we perform an LTE equivalent width analysis to derive these abundances. We look to literature sources to correct the abundances for non-LTE effects, especially for O, S, and K, where the corrections are large (often >0.2 dex). With these abundances and the ratios thereof, we will begin to paint clearer pictures of the planetary systems analyzed by this work. With our analysis, we can gain insight into the composition and extent of migration of Hot Jupiters, as well as the possibility of carbon-rich terrestrial worlds.

Keywords: exoplanets; planet hosting stars; stellar abundances; abundance ratios
The Gamma-Ray Pulsar Phenomenology in View of 3D Kinetic Global Magnetosphere Models

We develop kinetic plasma models of pulsar magnetospheres with magnetic-field-line-dependent plasma injection that reveal the importance of various magnetosphere regions in regulating the γ-ray emission. We set different particle injection rates for the so-called open, closed, and separatrix zones. Moderate particle injection rates in open and closed zones ensure a global field structure close to the force-free structure, while the dissipation occurs mainly in and around the equatorial current sheet. The particles that are injected into the separatrix zone affect the particle populations that enter the equatorial current sheet region, and therefore the corresponding accelerating electric fields, particle energies, the spectral cutoff energy, and γ-ray efficiency. The separatrix zone models reproduce the recently discovered fundamental plane of γ-ray pulsars consistent with curvature radiation emission, the γ-ray light-curve shapes, and the radio-lag versus peak-separation correlation reported in the Fermi second pulsar catalog. The model beaming factors indicate that the pulsar total γ-ray luminosities listed in the Fermi catalogs are overestimations of the actual ones. We find that the radiation reaction limited regime starts ceasing to govern the high-energy emission for $\dot{{ \mathcal E }}\lesssim {10}^{34}\,\mathrm{erg}\,\,{{\rm{s}}}^{-1}$ . Our results also indicate that toward high magnetic inclination angles, the Y point around the rotational equator migrates well inside the light cylinder, sparking additional peaks in the γ-ray pulse profiles. We find that an equivalent enhanced particle injection beyond the Y point strengthens these features, making the model γ-ray light curves inconsistent with those observed.

Keywords: pulsars; gamma-rays; gamma-ray telescopes; computational methods; neutron stars
The Core Population and Kinematics of a Massive Clump at Early Stages: An Atacama Large Millimeter/submillimeter Array View

High-mass star formation theories make distinct predictions on the properties of the prestellar seeds of high-mass stars. Observations of the early stages of high-mass star formation can provide crucial constraints, but they are challenging and scarce. We investigate the properties of the prestellar core population embedded in the high-mass clump AGAL014.492-00.139, and we study the kinematics at the clump and clump-to-core scales. We have analyzed an extensive data set acquired with the Atacama Large Millimeter/submillimeter Array interferometer. Applying a dendrogram analysis to the Band 7 o‑H2D+ data, we identified 22 cores. We fitted their average spectra in local thermodinamic equilibrium conditions, and we analyzed their continuum emission at 0.8 mm. The cores have transonic to mildly supersonic turbulence levels and appear to be mostly low-mass, with ${M}_{\mathrm{core}}\lt 30\,{\text{}}{M}_{\odot }$ . Furthermore, we have analyzed Band 3 observations of the N2H+ (1-0) transition, which traces the large-scale gas kinematics. Using a friend-of-friend algorithm, we identify four main velocity coherent structures, all of which are associated with prestellar and protostellar cores. One of them presents a filament-like structure, and our observations could be consistent with mass accretion toward one of the protostars. In this case, we estimate a mass accretion rate of ${\dot{M}}_{\mathrm{acc}}\approx 2\times {10}^{-4}\,{\text{}}{M}_{\odot }\,{\mathrm{yr}}^{-1}$ . Our results support a clump-fed accretion scenario in the target source. The cores in the prestellar stage are essentially low-mass, and they appear to be subvirial and gravitationally bound, unless further support is available, for instance, due to magnetic fields.

Keywords: star formation; massive stars; interferometry; astrochemistry; star forming regions; interstellar line emission
Multiline Stokes Synthesis of Ellerman Bombs: Obtaining Seamless Information from Photosphere to Chromosphere

Magnetic reconnection in the lower atmosphere is a critical process in determining the chromospheric dynamics, such as Ellerman bombs and UV bursts. Because the heating of the atmosphere significantly depends on the ionization degree and plasma β, which varies with height, it is essential to diagnose the height at which the magnetic reconnection takes place. Multiwavelength spectropolarimetry is a powerful solution to fulfill this requirement. We verify the diagnostic capabilities and usefulness of near-infrared multiwavelength spectropolarimetric observations for understanding magnetic reconnection phenomena by synthesizing the Stokes vector from a realistic magnetohydrodynamic simulation. The analysis considers two magnetic reconnection regions occurring at different heights. In the case of magnetic reconnection at low altitude, both red- and blueshifted components originating from reconnection bidirectional flow are identified in the photospheric lines, Fe I 8468 Å, K I 7664 Å, and K I 7698 Å. In the case of magnetic reconnection at high altitudes, chromospheric lines, Ca II 8498 Å and 8542 Å, show emission due to the heating that occurs at the upper part of the formation layer. These results suggest that multiwavelength spectropolarimetric observations are capable of distinguishing the height where magnetic reconnection occurs.

Keywords: solar physics; spectropolarimetry; high altitude balloons; solar magnetic fields; solar magnetic reconnection; radiative transfer; radiative magnetohydrodynamics; near infrared astronomy; solar chromosphere; solar photosphere
Radio Pulse Profiles and Polarization of the Terzan 5 Pulsars

Terzan 5 is a rich globular cluster within the galactic bulge containing 39 known millisecond pulsars, the largest known population of any globular cluster. These faint pulsars do not have sufficient signal-to-noise ratio (S/N) to measure reliable flux density or polarization information from individual observations in general. We combined over 5.2 days of archival data, at 1500 and 2000 MHz, taken with the Green Bank Telescope over the past 12 years. We created high-S/N profiles for 32 of the pulsars and determined precise rotation measures (RMs) for 28. We used the RMs, pulsar positions, and dispersion measures to map the projected parallel component of the Galactic magnetic field toward the cluster. The <B ∣∣> shows a rough gradient of ~6 nG arcsec-1 (~160 nG pc-1) or, fractionally, a change of ~20% in the R.A. direction across the cluster, implying Galactic magnetic field variability at sub-parsec scales. We also measured average flux densities S ν for the pulsars, ranging from ~10 μJy to ~2 mJy, and an average spectral index α = -1.35, where S ν ∝ ν α . This spectral index is flatter than most known pulsars, likely a selection effect due to the high frequencies used in pulsar searches to mitigate dispersion and scattering. We used flux densities from each observation to constrain the scintillation properties toward the cluster, finding strong refractive modulation on timescales of months. The inferred pulsar luminosity function is roughly power law, with slope $(d\mathrm{log}N)/(d\mathrm{log}L)=-1$ at the high-luminosity end. At the low-luminosity end, there are incompleteness effects, implying that Terzan 5 contains many more pulsars.

Keywords: millisecond pulsars; galaxy magnetic fields; globular star clusters
A Closer Look at Two of the Most Luminous Quasars in the Universe

Ultraluminous quasars (M1450 ≤ -29) provide us with a rare view into the nature of the most massive and most rapidly accreting supermassive black holes (SMBHs). Following the discovery of two of these extreme sources, J0341+1720 (M1450 = -29.56, z = 3.71) and J2125-1719 (M1450 = -29.39, z = 3.90), in the Extremely Luminous Quasar Survey (ELQS) and its extension to the Pan-STARRS 1 footprint (PS-ELQS), we herein present an analysis of their rest-frame UV to optical spectroscopy. Both quasars harbor very massive SMBHs with ${M}_{\mathrm{BH}}={6.73}_{-0.83}^{+0.75}\times {10}^{9}\,{M}_{\odot }$ and ${M}_{\mathrm{BH}}={5.45}_{-0.55}^{+0.60}\times {10}^{9}\,{M}_{\odot }$, respectively, showing evidence of accretion above the Eddington limit ( ${L}_{\mathrm{bol}}/{L}_{\mathrm{Edd}}={2.74}_{-0.27}^{+0.39}$ and ${L}_{\mathrm{bol}}/{L}_{\mathrm{Edd}}={3.01}_{-0.30}^{+0.34}$ ). NOEMA 3 millimeter observations of J0341+1720 reveal a highly star-forming (SFR ≈ 1500 M⊙ yr-1), ultraluminous infrared galaxy (LIR ≈ 1.0 × 1013 L⊙) host, which, based on an estimate of its dynamical mass, is only ∼30 times more massive than the SMBH it harbors at its center. As examples of luminous super-Eddington accretion, these two quasars provide support for theories that explain the existence of billion solar mass SMBHs ∼700 million years after the Big Bang by moderate super-Eddington growth from standard SMBH seeds.

Keywords: supermassive black holes; quasars; astrophysical black holes; active galactic nuclei; agn host galaxies; millimeter astronomy; spectroscopy; active galaxies; ultraluminous infrared galaxies
On Strong Correlation between Shifted Velocity and Line Width of Broad Blueshifted [O III] Components in Quasars

We report strong linear correlation between shifted velocity and line width of the broad blueshifted [O III] components in Sloan Digital Sky Survey (SDSS) quasars. Broad blueshifted [O III] components are commonly treated as indicators of outflows related to a central engine; however, it is still an open question whether the outflows are related to central accretion properties or related to local physical properties of narrow emission-line regions (NLRs). Here, the reported strong linear correlation with Spearman rank correlation coefficient 0.75 can be expected under the assumption of active galactic nuclei (AGNs) feedback-driven outflows, through a large sample of 535 SDSS quasars with reliable blueshifted broad [O III] components. Moreover, there are very different detection rates for broad blueshifted and broad redshifted [O III] components in quasars, and no positive correlation can be found between shifted velocity and line width of the broad redshifted [O III] components, which provides further and strong evidence to reject the possibility of local outflows in NLRs leading to the broad blueshifted [O III] components in quasars. Thus, the strong linear correlation can be treated as strong evidence for the broad blueshifted [O III] components being better indicators of outflows related to central engine in AGNs. Furthermore, rather than central black hole masses, Eddington ratios and continuum luminosities have key roles in the properties of the broad blueshifted [O III] components in quasars.

Keywords: active galactic nuclei; emission line galaxies; quasars; supermassive black holes