adsabs/SciX_UAT_keywords huggingface dataset:
The Occurrence of Small, Short-period Planets Younger than 200 Myr with TESS

Within the first few hundreds of millions of years, many physical processes sculpt the eventual properties of young planets. NASA's Transiting Exoplanet Survey Satellite (TESS) mission has surveyed young stellar associations across the entire sky for transiting planets, providing glimpses into the various stages of planetary evolution. Using our own detection pipeline, we search a magnitude-limited sample of 7219 young stars (≲200 Myr) observed in the first 4 yr of TESS for small (2–8 R ⊕), short period (1.6–20 days) transiting planets. The completeness of our survey is characterized by a series of injection and recovery simulations. Our analysis of TESS 2 minute cadence and Full Frame Image (FFI) light curves recover all known TESS Objects of Interest (TOIs), as well as four new planet candidates not previously identified as TOIs. We derive an occurrence rate of ${35}_{-10}^{+13} \% $ for mini-Neptunes and ${27}_{-8}^{+10} \% $ for super-Neptunes from the 2 minute cadence data, and ${22}_{-6.8}^{+8.6}$ % for mini-Neptunes and ${13}_{-4.9}^{+3.9}$ % for super-Neptunes from the FFI data. To independently validate our results, we compare our survey yield with the predicted planet yield assuming Kepler planet statistics. We consistently find a mild increase in the occurrence of super-Neptunes and a significant increase in the occurrence of Neptune-sized planets with orbital periods of 6.2–12 days when compared to their mature counterparts. The young planet distribution from our study is most consistent with evolution models describing the early contraction of hydrogen-dominated atmospheres undergoing atmospheric escape and inconsistent with heavier atmosphere models offering only mild radial contraction early on.

Keywords: exoplanets; mini neptunes; transit photometry; exoplanet evolution; planetary system evolution; young star clusters; exoplanet astronomy
Toroidal Magnetic Flux Budget in Mean-field Dynamo Model of Solar Cycles 23 and 24

We study the toroidal magnetic flux budget of the axisymmetric part of a data-driven 3D mean-field dynamo model of Solar Cycles 23 and 24. The model simulates the global solar dynamo that includes the effects of the formation and evolution of bipolar magnetic regions (BMRs) emerging on the solar surface. By applying Stokes's theorem to the dynamo induction equation, we show that the hemispheric magnitude of the net axisymmetric toroidal magnetic field generation rate in the bulk of the convection zone can only partially be estimated from the surface parameters of the differential rotation and the axisymmetric radial magnetic field. The contribution of the radial integral along the equator, which is mostly due to the rotational radial shear at the bottom of the convection zone, has the same magnitude and is nearly in phase with the effect of the surface latitudinal differential rotation. Also, the toroidal field generation rate estimate strongly depends on the latitudinal profile of the surface radial magnetic field near the poles. This profile in our dynamo models significantly deviates from the polar magnetic field distribution observed during the minima of Solar Cycles 22, 23, and 24. The cause of this discrepancy requires further observational and theoretical studies. Comparing the 2D axisymmetric and the 3D nonaxisymmetric dynamo models, we find an increase in the toroidal field generation rate in the 3D model due to the surface effects of BMRs, resulting in an increase in the axisymmetric poloidal magnetic field magnitude.

Keywords: solar cycle; the sun; solar dynamo
Halo-model Analysis of the Clustering of Photometric Luminous Red Galaxies at 0.10 ≤ z ≤1.05 from the Subaru Hyper Suprime-Cam Survey

We present the clustering analysis of photometric luminous red galaxies (LRGs) at a redshift range of 0.1 ≤ z ≤ 1.05 using 615,317 photometric LRGs selected from the Hyper Suprime-Cam Subaru Strategic Program, covering ~124 deg2. Our sample covers a broad range of stellar masses and photometric redshifts and enables a halo occupation distribution analysis to study the redshift and stellar-mass dependence of dark halo properties of LRGs. We find a tight correlation between the characteristic dark halo mass to host central LRGs, ${M}_{\min }$ , and the number density of LRGs, independently of redshifts, indicating that the formation of LRGs is associated with the global environment. The ${M}_{\min }$ of LRGs depends only weakly on the stellar mass M⋆ at M⋆ ≲ 1010.75h-2M⊙ at 0.3 < z < 1.05, in contrast to the case for all photometrically selected galaxies, for which ${M}_{\min }$ shows significant dependence on M⋆ even at low M⋆. The weak stellar-mass dependence is indicative of the dark halo mass being the key parameter for the formation of LRGs, rather than the stellar mass. Our result suggests that the halo mass of ~1012.5±0.2h-1M⊙ is the critical mass for an efficient halo quenching due to the halo environment. We compare our result with the result of the hydrodynamical simulation to find that low-mass LRGs at z ~ 1 will increase their stellar masses by an order of magnitude from z = 1 to 0 through mergers and satellite accretions, and that a large fraction of massive LRGs at z < 0.9 consist of LRGs that recently migrated from massive green valley galaxies or those that evolved from less massive LRGs through mergers and satellite accretions.

Keywords: galaxy evolution; observational cosmology; galaxy formation; galaxy dark matter halos; clustering; large-scale structure of the universe
Near-infrared Photometry of the Moon's Surface with Passive Radiometry from the Lunar Orbiter Laser Altimeter (LOLA)

Examining the reflectance of the Moon's surface across a broad range of viewing geometries through photometric analysis can reveal physical and geological properties of its regolith. Since 2013 December, the Lunar Orbiter Laser Altimeter (LOLA) on board the Lunar Reconnaissance Orbiter (LRO) has been operating as a near-infrared (1064 nm) passive radiometer when its laser is turned off. We present a new analysis of this data set spanning roughly 8 yr and covering the surface up to high latitudes in both hemispheres. We apply semiempirical phase functions to find a lower photometric slope and a narrower opposition effect for the highlands than the maria, consistent with theoretical expectations given the higher albedo of the highlands. Examining various geological properties at global scales shows that, in the highlands, iron abundance (FeO) and optical maturity (OMAT) are the dominant factors affecting the phase function, with a smaller influence from surface slope. In the maria, FeO is the dominant factor, with smaller influences from OMAT, surface slope, and TiO2. Submicroscopic iron abundance (SMFe) has a similar effect to OMAT in both highlands and maria. Analysis at specific sites, including the Reiner Gamma swirl and several silicic anomalies, indicates that the phase functions are consistent with the global data for similar FeO and OMAT. Thermophysical properties inferred from surface temperature observations by the Diviner Lunar Radiometer Experiment on board LRO do not affect the 1064 nm phase function, possibly due to a difference between their depth scale and LOLA's sensing depth.

Keywords: the moon; lunar regolith; lunar science; lunar features; remote sensing
On the Root Cause of the Host "Mass Step" in the Hubble Residuals of Type Ia Supernovae

It is well established that the Hubble residuals of Type Ia supernovae (SNe Ia) show the luminosity step with respect to their host galaxy stellar masses. This "mass step" is taken as an additional correction factor for the SN Ia luminosity standardization. Here we investigate the root cause of the mass step and propose that the bimodal nature of the host age distribution is responsible for the step. In particular, by using the empirical nonlinear mass-to-age relation of local galaxies, we convert the mass function of SN Ia hosts to their age distribution. We find that the age distribution shows clear bimodality: a younger (<6 Gyr) group with lower mass (~109.5 M Sun) and an older (> 6 Gyr) group with higher mass (~1010.5 M Sun). On the Hubble residual versus host-mass plane, the two groups create the mass step at ~1010 M Sun. This leads us to conclude that the host galaxy mass step can be attributed to the bimodal age distribution in relation to a nonlinear relation between galaxy mass and age. We suggest that the mass step is another manifestation of the old "red sequence" and the young "blue cloud" observed in the galactic color-magnitude diagram.

Keywords: galaxy ages; observational cosmology; type ia supernovae; galaxy evolution
Late-phase Spectropolarimetric Observations of Superluminous Supernova SN 2017egm to Probe the Geometry of the Inner Ejecta

We present our spectropolarimetric observations of SN 2017egm, a Type I superluminous supernova (SLSN-I) in a nearby galaxy NGC 3191, with the Subaru telescope at +185.0 days after the g-band maximum light. This is the first spectropolarimetric observation for SLSNe at late phases. We find that the degree of the polarization in the late phase significantly changes from that measured at the earlier phase. The spectrum at the late phase shows a strong Ca emission line and therefore we reliably estimate the interstellar polarization (ISP) component assuming that the emission line is intrinsically unpolarized. By subtracting the estimated ISP, we find that the intrinsic polarization at the early phase is only ∼0.2%, which indicates an almost spherical photosphere, with an axial ratio ∼1.05. The intrinsic polarization at the late phase increases to ∼0.8%, which corresponds to the photosphere with an axial ratio ∼1.2. A nearly constant position angle of the polarization suggests the inner ejecta are almost axisymmetric. By these observations, we conclude that the inner ejecta are more aspherical than the outer ejecta. This may suggest the presence of a central energy source producing aspherical inner ejecta.

Keywords: supernovae; spectropolarimetry
Hot Plasma Effects on the Pitch-angle Scattering Rates of Radiation Belt Electrons Due to Plasmaspheric Hiss

Plasmaspheric hiss is known to be a major contributor to the dynamic losses of Earth's radiation belt electrons. While previous computation attempts of hiss-driven electron losses are limited to the cold plasma approximation, in this study we find that hot plasma effects will modify the hiss dispersion relation and result in changes in the electron bounce-averaged electron pitch angle diffusion coefficients. Cold plasma approximation tends to overestimate the diffusion coefficients of ≲100 keV electrons by orders of magnitude, while the scattering efficiency of higher energy electrons is not greatly affected. As the L-shell decreases or the parameter $\alpha * \,=\,{{\rm{\Omega }}}_{e}^{2}/{\omega }_{\mathrm{pe}}^{2}$ decreases (where ${{\rm{\Omega }}}_{e}$ is the electron gyrofrequency and ${\omega }_{\mathrm{pe}}$ is the plasma frequency), the decrease of diffusion coefficients of low energy electrons caused by hot plasma effects become more pronounced. It is also shown that both the increase of hot electron abundance and temperature anisotropy can weaken the scattering efficiency of ≲100 keV electrons at almost all pitch angles, while the diffusion coefficients of higher energy electrons decrease at large pitch angles. Our study confirms the importance of including hot plasma effects in evaluations of hiss-driven scattering loss of radiation belt electrons.

Keywords: van allen radiation belts; planetary magnetospheres; space plasmas
The Influence of Stellar Phosphorus on Our Understanding of Exoplanets and Astrobiology

When searching for exoplanets and ultimately considering their habitability, it is necessary to consider the planet's composition, geophysical processes, and geochemical cycles in order to constrain the bioessential elements available to life. Determining the elemental ratios for exoplanetary ecosystems is not yet possible, but we generally assume that planets have compositions similar to those of their host stars. Therefore, using the Hypatia Catalog of high-resolution stellar abundances for nearby stars, we compare the C, N, Si, and P abundance ratios of main-sequence stars with those in average marine plankton, Earth's crust, as well as bulk silicate Earth and Mars. We find that, in general, plankton, Earth, and Mars are N-poor and P-rich compared with nearby stars. However, the dearth of P abundance data, which exists for only ∼1% of all stars and 1% of exoplanet hosts, makes it difficult to deduce clear trends in the stellar data, let alone the role of P in the evolution of an exoplanet. Our Sun has relatively high P and Earth biology requires a small, but finite, amount of P. On rocky planets that form around host stars with substantially less P, the strong partitioning of P into the core could rule out the potential for surface P and, consequently, for life on that planet's surface. Therefore, we urge the stellar abundance community to make P observations a priority in future studies and telescope designs.

Keywords: exoplanet structure; stellar abundances; astrobiology; interdisciplinary astronomy
LOTUS: A (Non-) LTE Optimization Tool for Uniform Derivation of Stellar Atmospheric Parameters

Precise fundamental atmospheric stellar parameters and abundance determination of individual elements in stars are important for all stellar population studies. Non-local thermodynamic equilibrium (non-LTE; hereafter NLTE) models are often important for such high precision, however, can be computationally complex and expensive, which renders the models less utilized in spectroscopic analyses. To alleviate the computational burden of such models, we developed a robust 1D, NLTE fundamental atmospheric stellar parameter derivation tool, LOTUS, to determine the effective temperature T eff, surface gravity $\mathrm{log}g$ , metallicity [Fe/H], and microturbulent velocity v mic for FGK-type stars, from equivalent width (EW) measurements of Fe I and Fe II lines. We utilize a generalized curve of growth method to take into account the EW dependencies of each Fe I and Fe II line on the corresponding atmospheric stellar parameters. A global differential evolution optimization algorithm is then used to derive the fundamental parameters. Additionally, LOTUS can determine precise uncertainties for each stellar parameter using a Markov Chain Monte Carlo algorithm. We test and apply LOTUS on a sample of benchmark stars, as well as stars with available asteroseismic surface gravities from the K2 survey, and metal-poor stars from the Gaia-ESO and R-Process Alliance surveys. We find very good agreement between our NLTE-derived parameters in LOTUS to nonspectroscopic values on average within T eff = ±30 K, and $\mathrm{log}g$ = ±0.10 dex for benchmark stars. We provide open access of our code, as well as of the interpolated precomputed NLTE EW grids available on Github (the software is available on GitHub 3 3 https://github.com/Li-Yangyang/LOTUS under an MIT License, and version 0.1.1 (as the persistent version) is archived in Zenodo) and documentation with working examples on the Readthedocs book.

Keywords: stellar physics; stellar atmospheres; astronomical techniques; spectroscopy; stellar abundances; effective temperature; surface gravity; metallicity; fundamental parameters of stars; stellar photospheres
Synchrotron Radiation Dominates the Extremely Bright GRB 221009A

The brightest gamma-ray burst, GRB 221009A, has spurred numerous theoretical investigations, with particular attention paid to the origins of ultrahigh-energy TeV photons during the prompt phase. However, analyzing the mechanism of radiation of photons in the ~MeV range has been difficult because the high flux causes pileup and saturation effects in most GRB detectors. In this Letter, we present systematic modeling of the time-resolved spectra of the GRB using unsaturated data obtained from the Fermi Gamma-ray Burst Monitor (precursor) and SATech-01/GECAM-C (main emission and flare). Our approach incorporates the synchrotron radiation model, which assumes an expanding emission region with relativistic speed and a global magnetic field that decays with radius, and successfully fits such a model to the observational data. Our results indicate that the spectra of the burst are fully in accordance with a synchrotron origin from relativistic electrons accelerated at a large emission radius. The lack of thermal emission in the prompt emission spectra supports a Poynting flux-dominated jet composition.

Keywords: gamma-ray bursts
The Reddening and [O II] Emissions of the Quasar Mg II Absorption-line Systems

Using quasar Mg II narrow absorption lines (NALs) with velocity offset ( $\beta \equiv \tfrac{{\upsilon }_{r}}{c}=\tfrac{{\left(1+{z}_{\mathrm{em}}\right)}^{2}-({1+{z}_{\mathrm{abs}})}^{2}}{{\left(1+{z}_{\mathrm{em}}\right)}^{2}+{\left(1+{z}_{\mathrm{abs}}\right)}^{2}}$ , where c is the speed of light) ${\upsilon }_{r}\lt {\rm{10,000}}$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ , this paper investigates the $[{\rm{O}}\,{\rm{II}}]$ emissions and reddening associated with Mg II NALs by constructing composite spectra. Dust extinctions of all the inflow ( ${\upsilon }_{r}\lt -750$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ ), environment (-750 ≤ $\upsilon $ r < 600 $\mathrm{km}\,{{\rm{s}}}^{-1}$ ), outflow ( $600\leqslant {\upsilon }_{r}\lt 2000$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ ), and strong intervening-like (2000 ≤ $\upsilon $ r < 6000 $\mathrm{km}\,{{\rm{s}}}^{-1}$ ) Mg II NALs can be described by the SMC extinction curve, which suggest that all four types of Mg II NALs have similar dust properties. The colors of quasars hosting intervening-like Mg II NALs with ${W}_{r}^{\lambda \leqslant 1.5}$ Å and intervening Mg II NALs ( ${\upsilon }_{r}\geqslant 6000$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ ) are similar to those of control quasars (without Mg II NALs with ${\upsilon }_{r}\lt {\rm{10,000}}$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ ), which suggests that these two types of Mg II NALs are mainly formed within media unconnected with background quasars. The other three types of Mg II NALs have much more obvious reddening to background quasars, and the stronger absorptions or the absorptions detected in radio detected quasars produce larger reddening than the weaker absorptions or the absorptions in radio undetected quasars. In addition, the dust-to-gas ratios within inflow Mg II NALs are possibly lower than those within environment ones. We find that flux ratios $[{\rm{O}}\,{\rm{II}}]$ / $[\mathrm{Ne}\,{\rm{V}}]$ of quasars hosting inflow, outflow, intervening-like, and intervening Mg II NALs are similar to those of control quasars. For quasars hosting environment Mg II NALs, (1) the flux ratio $[{\rm{O}}\,{\rm{II}}]$ / $[\mathrm{Ne}\,{\rm{V}}]$ is much higher than that of control quasars, which suggests that there is a high star formation rate within the host galaxies of environment Mg II NALs; (2) the flux ratio $[{\rm{O}}\,{\rm{II}}]$ / $[\mathrm{Ne}\,{\rm{V}}]$ is positively correlated with absorption strengths; and (3) radio detected quasars have a slightly higher flux ratio $[{\rm{O}}\,{\rm{II}}]$ / $[\mathrm{Ne}\,{\rm{V}}]$ when compared to radio undetected quasars, which suggests that the quasar feedback enhances the star formation rate within host galaxies of environment absorbers. For quasars hosting outflow Mg II NALs, we find that $[{\rm{O}}\,{\rm{II}}]$ emission lines display excesses at blue wings with respect to the line profiles of control quasars, and the excesses are positively correlated with absorption strengths.

Keywords: interstellar dust extinction; active galactic nuclei; quasar absorption line spectroscopy; interstellar medium; emission nebulae
The TESS View of LOFAR Radio-emitting Stars

The recent detection of the M dwarf GJ 1151 at 144 MHz low radio frequencies using LOFAR has been interpreted as evidence of an exoplanet magnetically interacting with its host star. This would be the first exoplanet detected around a main-sequence star by a radio telescope. Radial velocity confirmation of such a planet has proven inconclusive and it remains possible that the radio emission could be generated by a stellar coronal process. Using data from TESS, we shed light on this question by probing the stellar activity and flares of GJ 1151 as well as 14 other M dwarfs detected by LOFAR. GJ 1151 and three other star-planet interaction candidates are found to be inactive, with no rotational modulation and few, if any, flares. The remainder of the LOFAR-detected M dwarfs flare frequently. We consider it unlikely that stellar activity is responsible for the bright, circularly polarized emission from GJ 1151 and its three analogs and support the star-planet magnetic interaction interpretation.

Keywords: exoplanet astronomy; habitable zone; star-planet interactions; m dwarf stars
A Simple Method for Predicting N H Variability in Active Galactic Nuclei

The unified model of active galactic nuclei (AGNs) includes a geometrically thick obscuring medium to explain the differences between type I and type II AGNs as an effect of inclination angle. This medium is often referred to as the torus and is thought to be "clumpy" as the line-of-sight column density, N H, has been observed to vary in time for many sources. We present a method which uses a variation in the hardness ratio to predict whether an AGN has experienced N H variability across different observations. We define two sets of hard and soft bands that are chosen to be sensitive to the energies most affected by changes in N H. We calculate hardness ratios for Chandra and XMM-Newton observations of a sample of 12 sources with multiple observations, and compare the predictions of this method to the N H values obtained from spectral fitting with physically motivated torus models (borus02, MYTorus, and UXCLUMPY). We also provide a calibrated correction factor that allows comparison between Chandra and XMM-Newton observations which is otherwise not possible due to differences in the instrument response functions. The sensitivity of this method can be easily adjusted. As we decrease the sensitivity, we find that the false positive rate becomes small while the true positive rate remains above 0.5. We also test the method on simulated data and show that it remains reliable for observations with as few as 100 counts. Therefore, we conclude that the method proposed in this work is effective in preselecting sources for variability studies.

Keywords: x-ray active galactic nuclei; seyfert galaxies; active galactic nuclei; high energy astrophysics; x-ray astronomy