adsabs/SciX_UAT_keywords huggingface dataset:
Carbon Abundance of Stars in the LAMOST-Kepler Field

The correlation between host star iron abundance and the exoplanet occurrence rate is well established and arrived at in several studies. Similar correlations may be present for the most abundant elements, such as carbon and oxygen, which also control the dust chemistry of the protoplanetary disk. In this paper, using a large number of stars in the Kepler field observed by the LAMOST survey, it has been possible to estimate the planet occurrence rate with respect to the host star carbon abundance. Carbon abundances are derived using synthetic spectra fit of the CH- G-band region in the LAMOST spectra. The carbon abundance trend with metallicity is consistent with the previous studies and follows the Galactic chemical evolution (GCE). Similar to [Fe/H], we find that the [C/H] values are higher among giant-planet hosts. The trend between [C/Fe] and [Fe/H] in planet hosts and single stars is similar; however, there is a preference for giant planets around host stars with a subsolar [C/Fe] ratio and higher [Fe/H]. Higher metallicity and subsolar [C/Fe] values are found among younger stars as a result of GCE. Hence, based on the current sample, it is difficult to interpret the results as a consequence of GCE or due to planet formation.

Keywords: stellar abundances; exoplanet formation; spectroscopy; surveys; planet hosting stars; exoplanet catalogs
The Temperature and Density of a Solar Flare Kernel Measured from Extreme-ultraviolet Lines of O IV

Previously unexplored diagnostics of O IV in the extreme-ultraviolet region 260–280 Å are used to derive a temperature and density for a solar flare kernel observed on 2012 March 9 with the Extreme-ultraviolet Imaging Spectrometer on the Hinode satellite. Seven lines from the 2s2p 2–2s2p3s transition array between 271.99 and 272.31 Å are both temperature- and density-sensitive relative to the line at 279.93 Å. The temperature, T, is constrained with the λ268.02/λ279.93 ratio, giving a value of $\mathrm{log}(T/{\rm{K}})=5.10\pm 0.03$ . The ratio λ272.13/λ279.93 then yields an electron number density, N e, of $\mathrm{log}({N}_{{\rm{e}}}/{\mathrm{cm}}^{-3})=12.52$ with a lower limit of 11.90 and an upper limit of 14.40. The O IV emitting volume is estimated to be 0.″4 (300 km) across. Additional O IV lines at 196, 207, and 260 Å are consistent with the derived temperature and density but have larger uncertainties from the radiometric calibration and blending. Density diagnostics of O V and Mg VII from the same spectrum are consistent with a constant pressure of 1017.0 K cm‑3 through the transition region. The temperature derived from O IV supports recent results that O IV is formed around 0.10 dex lower at high densities compared to standard zero-density ionization balance calculations.

Keywords: ultraviolet spectroscopy; solar transition region; solar flares; atomic data; solar flare spectra
Recurrently Propagating Intensity Disturbances along Polar Plumes Observed in White Light and Extreme Ultraviolet

We study properties of intensity disturbances along polar coronal rays that are associated with plumes below. For this, we draw azimuth–time images of extreme ultraviolet (EUV) emission of 171 Å band observed by the SDO/AIA and white light (WL) observed by the SOHO/LASCO C2 in 2020 July. From the azimuth–time image, we define two tracks in which the EUV intensities were recurrently enhanced during two weeks. The two EUV tracks are rooted at 78.°8 and 81.°4 latitudes, but their projected azimuth angles are changed with time as the Sun rotates. Coherent WL tracks at different altitudes are determined by scaling the azimuth angles of the EUV tracks, accounting for the effect of inclination of coronal rays. From this, we construct time–distance images of WL intensities along WL tracks, whose projected azimuth angle changes along time and altitude, but the intensities are correlated with the EUV intensities measured below. The time–distance images of WL show repeated and inclined intensity features. The propagation speeds in the altitude range 2.3–6 solar radii are calculated to be 159 ± 8 km s‑1 and 300 ± 24 km s‑1. The EUV and WL intensities are found to be coherent at 1–2 day periods. It is also found that dynamic burst events along the EUV track are responsible for the enhanced emission. We conclude that the variation of the WL intensity along the polar coronal rays is related with the evolution of the EUV intensity below.

Keywords: the sun; solar coronal plumes; solar wind
Broadening Astronomy Education through Professional Development

We report on the processes and findings related to the iterative design of the San Antonio Teacher Training Astronomy Academy (SATTAA). In particular, we show how the initial iteration in 2018, limited to only future (or preservice) secondary school STEM teachers, broadened to include current (or in-service) secondary school teachers in 2019, and then added primary school pre- and in-service teachers in 2020. The participants of all three years are now part of a community of practice that continues to engage in astronomy education in varied ways.

Keywords: astronomy education
Simulating the Solar Minimum Corona in UV Wavelengths with Forward Modeling II. Doppler Dimming and Microscopic Anisotropy Effect

In ultraviolet (UV) spectropolarimetric observations of the solar corona, the existence of a magnetic field, solar wind velocity, and temperature anisotropies modify the linear polarization associated with resonant scattering. Unlike previous empirical models or global models, which present blended results of the above physical effects, in this work, we forward-model expected signals in the H I Lyα line (121.6 nm) by adopting an analytic model that can be adjusted to test the roles of different effects separately. We find that the impact of all three effects is most evident in the rotation of the linear polarization direction. In particular, (1) for magnetic fields between ∼10 and ∼100 G, the Hanle effect modifies the linear polarization at low coronal heights, rotating the linear polarization direction clockwise (counterclockwise) when the angle between the magnetic field and the local vertical is greater (less) than the van Vleck angle, which is consistent with the result of Zhao et al.; (2) solar wind velocity, which increases with height, has a significant effect through the Doppler dimming effect at higher coronal heights, rotating the linear polarization direction in an opposite fashion to the Hanle effect; and (3) kinetic temperature anisotropies are most significant at lower heights in open nonradial magnetic field regions, producing tilt opposite to isotropic Doppler dimming. The fact that the three effects operate differently in distinct spatial regimes opens up the possibility for using linear polarization measurements in UV lines to diagnose these important physical characteristics of the solar corona.

Keywords: solar wind; coronagraphic imaging; solar ultraviolet emission
The EDGE-CALIFA Survey: Spatially Resolved 13CO(1-0) Observations and Variations in 12CO(1-0)/13CO(1-0) in Nearby Galaxies on Kiloparsec Scales

We present 13CO(J = 1 → 0) observations for the EDGE-CALIFA survey, which is a mapping survey of 126 nearby galaxies at a typical spatial resolution of 1.5 kpc. Using detected 12CO emission as a prior, we detect 13CO in 41 galaxies via integrated line flux over the entire galaxy and in 30 galaxies via integrated line intensity in resolved synthesized beams. Incorporating our CO observations and optical IFU spectroscopy, we perform a systematic comparison between the line ratio ${{ \mathcal R }}_{12/13}\equiv I{[}^{12}\mathrm{CO}(J=1\to 0)]/I{[}^{13}\mathrm{CO}(J=1\to 0)]$ and the properties of the stars and ionized gas. Higher ${{ \mathcal R }}_{12/13}$ values are found in interacting galaxies compared to those in noninteracting galaxies. The global ${{ \mathcal R }}_{12/13}$ slightly increases with infrared color F 60/F 100 but appears insensitive to other host-galaxy properties such as morphology, stellar mass, or galaxy size. We also present azimuthally averaged ${{ \mathcal R }}_{12/13}$ profiles for our sample up to a galactocentric radius of 0.4r 25 (~6 kpc), taking into account the 13CO nondetections by spectral stacking. The radial profiles of ${{ \mathcal R }}_{12/13}$ are quite flat across our sample. Within galactocentric distances of 0.2r 25, the azimuthally averaged ${{ \mathcal R }}_{12/13}$ increases with the star formation rate. However, Spearman rank correlation tests show the azimuthally averaged ${{ \mathcal R }}_{12/13}$ does not strongly correlate with any other gas or stellar properties in general, especially beyond 0.2r 25 from the galaxy centers. Our findings suggest that in the complex environments in galaxy disks, ${{ \mathcal R }}_{12/13}$ is not a sensitive tracer for ISM properties. Dynamical disturbances, like galaxy interactions or the presence of a bar, also have an overall impact on ${{ \mathcal R }}_{12/13}$ , which further complicates the interpretations of ${{ \mathcal R }}_{12/13}$ variations.

Keywords: galaxy evolution; molecular gas
Jetted and Turbulent Stellar Deaths: New LVK-detectable Gravitational-wave Sources

Upcoming LIGO-Virgo-KAGRA (LVK) observing runs are expected to detect a variety of inspiralling gravitational-wave (GW) events that come from black hole and neutron star binary mergers. Detection of noninspiral GW sources is also anticipated. We report the discovery of a new class of noninspiral GW sources-the end states of massive stars-that can produce the brightest simulated stochastic GW burst signal in the LVK bands known to date, and could be detectable in LVK run A+. Some dying massive stars launch bipolar relativistic jets, which inflate a turbulent energetic bubble-cocoon-inside of the star. We simulate such a system using state-of-the-art 3D general relativistic magnetohydrodynamic simulations and show that these cocoons emit quasi-isotropic GW emission in the LVK band, ~10-100 Hz, over a characteristic jet activity timescale ~10-100 s. Our first-principles simulations show that jets exhibit a wobbling behavior, in which case cocoon-powered GWs might be detected already in LVK run A+, but it is more likely that these GWs will be detected by the third-generation GW detectors with an estimated rate of ~10 events yr-1. The detection rate drops to ~1% of that value if all jets were to feature a traditional axisymmetric structure instead of a wobble. Accompanied by electromagnetic emission from the energetic core-collapse supernova and the cocoon, we predict that collapsars are powerful multimessenger events.

Keywords: gravitational waves; relativistic jets; stellar jets; gamma-ray bursts; gravitational wave sources; ligo; gravitational wave astronomy; core-collapse supernovae; magnetohydrodynamical simulations
Dwarf Galaxies with the Highest Concentration Are Not Thicker than Ordinary Dwarf Galaxies

The formation mechanism of high-concentration dwarf galaxies is still a mystery. We perform a comparative study of the intrinsic shape of nearby low-mass galaxies with different stellar concentration. The intrinsic shape is parameterized by the intermediate-to-major axis ratios B/A and the minor-to-major axis ratios C/A of triaxial ellipsoidal models. Our galaxies (107.5 M ⊙ < M ⋆ < 1010.0 M ⊙) are selected to have spectroscopic redshift from SDSS or GAMA and have broadband optical images from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) wide-layer survey. The deep HSC-SSP images allow to measure the apparent axis ratios q at galactic radii beyond the central star-forming area of our galaxies. We infer the intrinsic axis ratios based on the q distributions. We find that (1) our galaxies have typical intrinsic shape similarly close to be oblate (μ B/A ~ 0.9-1), regardless of the concentration, stellar mass, star formation activity, and local environment (being central or satellite); (2) galaxies with the highest concentration tend to have intrinsic thickness similar to or (in virtually all cases) slightly thinner (i.e., smaller mean μ C/A or equivalently lower triaxiality) than ordinary galaxies, regardless of other properties explored here. This appears to be in contrast with the expectation of the classic merger scenario for high-concentration galaxies. Given the lack of a complete understanding of dwarf-dwarf merger, we cannot draw a definite conclusion about the relevance of mergers in the formation of high-concentration dwarfs. Other mechanisms such as halo spin may also play important roles in the formation of high-concentration dwarf galaxies.

Keywords: dwarf galaxies
DIAmante TESS AutoRegressive Planet Search (DTARPS). II. Hundreds of New TESS Candidate Exoplanets

The DIAmante TESS AutoRegressive Planet Search for the southern ecliptic hemisphere (DTARPS-S) project seeks to identify photometric transiting planets from 976,814 southern hemisphere stars observed in Year 1 of the TESS mission. This paper follows the methodology developed by Melton et al. (Paper I) using light curves extracted and preprocessed by the DIAmante project. Paper I emerged with a list of 7377 light curves with statistical properties characteristic of transiting planets but dominated by false alarms and false positives. Here a multistage vetting procedure is applied including: centroid motion and crowding metrics, false alarm and false positive reduction, photometric binary elimination, and ephemeris match removal. The vetting produces a catalog of 462 DTARPS-S candidates across the southern ecliptic hemisphere and 310 objects in a spatially incomplete Galactic plane list. 58% were not previously identified as transiting systems. Candidates are flagged for possible blending from nearby stars based on Zwicky Transient Facility data and for possible radial velocity variations based on Gaia satellite data. Orbital periods and planetary radii are refined using astrophysical modeling; the resulting parameters closely match published values for confirmed planets. The DTARPS-S population and astrophysical properties are discussed in Paper III.

Keywords: exoplanet catalogs; exoplanet detection methods; light curve classification; period search; time domain astronomy; transits
Diffuse Bands 9577 and 9633: Relations to Other Interstellar Features

We study, for the first time, the relations of two strong diffuse bands (DIBs) at 9633 and 9577 Å, commonly attributed to ${{\rm{C}}}_{60}^{+}$ , to other interstellar features seen in optical and UV spectra including H I, Ca I, Fe II, Na I, Ti II, CN, CH, CH+, and C2 and DIBs 5780, 5797, 6196, 6269, 6284, and 6614. We analyzed 62 lines of sight where the stellar contamination by Mg II was corrected or found negligible for DIB 9633. Equivalent widths of DIB 9577 were measured in 62 lines of sight. Poor mutual correlation between the strengths of the above features and the major diffuse bands (5780 and 5797) as well as with other DIBs (with some exceptions) were revealed. The considered DIBs are also poorly correlated with the features of neutral hydrogen, molecular carbon, and those of simple interstellar radicals. Perhaps this phenomenon can be explained if the diffuse band 9577 is an unresolved blend of two or more interstellar features. There are indications that 9633 and 9577 diffuse bands are stronger in σ-type clouds, i.e., these features resemble the behavior of reasonably broad DIBs, which are strong in the lines of sight where the UV flux from the very hot nearby stars plays an important role.

Keywords: interstellar medium; diffuse interstellar bands; interstellar line absorption; interstellar absorption
On the Origin of Metal-poor Stars in the Solar Neighborhood

We determined the ages, kinematic parameters, and Galactic orbital parameters of six metal-poor (-2.4 < [Fe/H] < -1.0 dex), F-type, high-proper-motion (HPM) stars to investigate their HPM nature and origin. For the kinematical procedure, the astrometric data from the Gaia DR2 were used. High-resolution ELODIE spectra of the six dwarfs were also used to obtain accurate [Fe/H] abundances and up-to-date [α/Fe] abundances. The calculations for stellar ages were based on Bayesian statistics, with the computed ages falling in the range 9.5-10.1 Gyr. On the basis of the metallicities and ages, six HMP stars are either members of the halo (HD 6755, HD 84937, BD +42 3607) or members of the low-metallicity tail of the thick disk (HD 3567, HD 194598, HD 201891). However, Galactic orbital parameters suggest thin disk (HD 84937, HD 194598), thick disk (HD 3567, HD 201891), and halo (HD 6755, BD +42 3607) populations. The dynamical analysis was also performed for the escape scenario from the candidate GCs. The tidal disruption of a dwarf galaxy was also considered as an alternative origin. HD 6755, HD 194598, and HD 3567, with their retrograde orbital motions, are likely candidate stars for a tidally disrupted dwarf galaxy origin. However, the relationship of HD 194598 with NGC 6284 presents an interesting case. Its encounter velocity is low (16 ± 28 km s-1), and their ages and metallicities are very nearly consistent with each other at the 1σ level. The rest of the HPM sample stars have a 4%-18% probability of encountering with selected GCs for 1.5 tidal radii. This indicates that a globular cluster origin for the program stars is unlikely.

Keywords: stellar abundances; chemical abundances; halo stars; high-velocity stars; stellar kinematics; stellar associations; solar neighborhood
COMAP Early Science. IV. Power Spectrum Methodology and Results

We present the power spectrum methodology used for the first-season COMAP analysis, and assess the quality of the current data set. The main results are derived through the Feed-Feed Pseudo-Cross-Spectrum (FPXS) method, which is a robust estimator with respect to both noise modeling errors and experimental systematics. We use effective transfer functions to take into account the effects of instrumental beam smoothing and various filter operations applied during the low-level data processing. The power spectra estimated in this way have allowed us to identify a systematic error associated with one of our two scanning strategies, believed to be due to residual ground or atmospheric contamination. We omit these data from our analysis and no longer use this scanning technique for observations. We present the power spectra from our first season of observing, and demonstrate that the uncertainties are integrating as expected for uncorrelated noise, with any residual systematics suppressed to a level below the noise. Using the FPXS method, and combining data on scales k = 0.051-0.62 Mpc-1, we estimate P CO(k) = -2. 7 ± 1.7 × 104 μK2 Mpc3, the first direct 3D constraint on the clustering component of the CO(1-0) power spectrum in the literature.

Keywords: co line emission; cosmological evolution; high-redshift galaxies; molecular gas; radio astronomy
Statistics for Galaxy Outflows at z ∼ 6–9 with Imaging and Spectroscopic Signatures Identified with JWST/NIRCam and NIRSpec Data

We present statistics of z ∼ 6–9 galaxy outflows indicated by spatially extended gas emission and broad lines. With a total of 61 spectroscopically confirmed galaxies at z ∼ 6–9 in the JWST CEERS, GLASS, and ERO data, we find four galaxies with [O III] + Hβ ionized gas emission significantly extended beyond the kiloparsec-scale stellar components on the basis of the emission line images constructed by the subtraction of NIRCam broadband (line on/off-band) images. By comparison with low-z galaxies, the fraction of galaxies with spatially extended gas, 4/18, at z ∼ 6–9 is an order of magnitude higher than that at z ∼ 0–1, which can be explained by events triggered by frequent major mergers at high redshift. We also investigate medium- and high-resolution NIRSpec spectra of 30 galaxies at z ∼ 6–9, and identify five galaxies with broad (140‑800 km s‑1) lines in the [O III] forbidden line emission, suggestive of galaxy outflows. One galaxy at z = 6.38 shows both spatially extended gas emission and the broad lines, while none of the galaxies with spatially extended gas emission or broad lines present a clear signature of active galactic nuclei (AGN) in either the line diagnostics or type 1 AGN line broadening (>1000 km s‑1), which suggests that outflows are mainly driven by stellar feedback. The existence of galaxies with/without spatially extended gas emission or broad lines may be explained by different viewing angles toward outflows or the fact that these are galaxies in the early, late, or post phases of galaxy outflows at high redshift, where relatively large fractions of such galaxies indicate longer-duration and/or more frequent outflows at early cosmic epochs.

Keywords: galaxy evolution; galaxy formation; circumgalactic medium
Evidence for a Rotational Component in the Circumgalactic Medium of Nearby Galaxies

We present results of a study comparing the relative velocity of Lyα absorbers to the rotation velocity of nearby galaxy disks in the local universe (z ≤ 0.03). We have obtained rotation curves via long-slit spectroscopy of eight galaxies with the Southern African Large Telescope, and combine this data set with an additional 16 galaxies with data from the literature. Each galaxy appears within 3Rvir of a QSO sightline with archival Cosmic Origin Spectrograph spectra. We study the velocity orientation of absorbers with respect to nearby galaxy's rotation, and compare with results from both the Steidel et al. monolithic halo model and a new cylindrical Navarro-Frenk-White galaxy halo model to interpret these data in the context of probing 3D galaxy halos via 1D QSO absorption-line spectroscopy. Relative to these models, we find that up to 59% ± 5% of Lyα absorbers have velocities consistent with corotation. We find the Lyα corotation fraction to decrease with galaxy luminosity (L*) and impact parameter in a model-independent fashion. We report that both anti-rotating absorbers and those found near luminous galaxies (L ≳ 0.5L*) mostly have low Doppler b-parameters (b ≲ 50 km s-1). Absorbers consistent with corotation show a wide range of Doppler b-parameters. Finally, we find a strong anticorrelation between corotation fraction and galaxy inclination, which is at odds with recent metal-line kinematic studies and suggests the kinematic and geometric distribution of the circumgalactic medium is complex and multiphase. * Based on observations made with the Southern African Large Telescope (SALT).

Keywords: galaxy evolution; extragalactic astronomy; galaxy accretion; intergalactic medium; circumgalactic medium; galaxy rotation curves; quasar absorption line spectroscopy; galaxy formation