adsabs/SciX_UAT_keywords huggingface dataset:
IC 5146 Dark Streamer: The First Reliable Candidate of Edge Collapse, Hub-filament Systems, and Intertwined Sub-filaments

The paper presents an analysis of multiwavelength data of a nearby star-forming site, the IC 5146 dark streamer (d ~ 600 pc), which has been treated as a single and long filament, fl. Two hub-filament systems (HFSs) are known to exist toward the eastern and the western ends of fl. Earlier published results favor simultaneous evidence of HFSs and end-dominated collapse (EDC) in fl. A Herschel column density map (resolution ~13.″5) reveals two intertwined sub-filaments (i.e., fl-A and fl-B) toward fl, displaying a nearly double helix-like structure. This picture is also supported by the C18O(3-2) emission. The fray and fragment scenario may explain the origin of intertwined sub-filaments. In the direction of fl, two cloud components around 2 and 4 km s-1 are depicted using 13CO(1-0) and C18O(1-0) emission and are connected in velocity space. The HFSs are spatially found at the overlapping areas of these cloud components and can be explained by the cloud-cloud collision scenario. Nonthermal gas motion in fl with a larger Mach number is found. The magnetic field position angle measured from the filament's long axis shows a linear trend along the filament. This signature is confirmed in the other nearby EDC filaments, presenting a more quantitative confirmation of the EDC scenario. Based on our observational outcomes, we witness multiple processes operational in the IC 5146 streamer. Overall, the streamer can be recognized as the first reliable candidate for edge collapse, HFSs, and intertwined sub-filaments.

Keywords: star forming regions; h ii regions; molecular clouds; interstellar emissions; young stellar objects
Minimum Mars Climate Sounder Retrieval Altitudes Reveal Cloud Altitudes at Aphelion and Stranded High-altitude Dust Following the MY34 Global Dust Storm on Mars

The Mars Climate Sounder (MCS) has been observing Mars' atmosphere since the Mars Reconnaissance Orbiter's arrival in 2006. While MCS can theoretically observe down to the surface, in practice the presence of aerosols such as dust and water ice can cut off retrievals at altitudes tens of kilometers above the surface. We examine the minimum cut-off altitudes of MCS temperature retrievals over the course of MCS's mission for the area around Gale Crater. We see a preference for cut-off altitudes above 20 km in the cloudy season and greater variation in preference in the dusty season. These cut-off altitudes can be used to infer cloud altitudes and to track the decay of significant dust storms as well as seeing the effects of stranded dust in the MY 34 global dust storm.

Keywords: mars; planetary atmospheres; atmospheric clouds; atmospheric variability; remote sensing
Coherent Stellar Motion in Galactic Spiral Arms by Swing Amplification

We perform local N-body simulations of disk galaxies and investigate the evolution of spiral arms. We calculate the time autocorrelation of the surface density of spiral arms and find that the typical evolution timescale is described by the epicycle period. We investigate the distribution of the orbital elements of stars and find that in spiral arms the epicycle motions of stars are in phase while the spatial distribution of the guiding center is nearly uniform. These facts clearly show that the phase synchronization of the epicycle motion takes place, which is theoretically predicted by the swing amplification.

Keywords: spiral arms; n-body simulations; galaxy dynamics
A Comprehensive Revisit of Select Galileo/NIMS Observations of Europa

The Galileo Near Infrared Mapping Spectrometer (NIMS) collected spectra of Europa in the 0.7-5.2 μm wavelength region, which have been critical to improving our understanding of the surface composition of this moon. However, most of the work done to get constraints on abundances of species like water ice, hydrated sulfuric acid, hydrated salts, and oxides has used proxy methods, such as absorption strength of spectral features or fitting a linear mixture of laboratory-generated spectra. Such techniques neglect the effect of parameters degenerate with the abundances, such as the average grain size of particles, or the porosity of the regolith. In this work we revisit three Galileo NIMS spectra, collected from observations of the trailing hemisphere of Europa, and use a Bayesian inference framework, with the Hapke reflectance model, to reassess Europa's surface composition. Our framework has several quantitative improvements relative to prior analyses: (1) simultaneous inclusion of amorphous and crystalline water ice, sulfuric-acid-octahydrate (SAO), CO2, and SO2; (2) physical parameters like regolith porosity and radiation-induced band-center shift; and (3) tools to quantify confidence in the presence of each species included in the model, constrain their parameters, and explore solution degeneracies. We find that SAO strongly dominates the composition in the spectra considered in this study, while both forms of water ice are detected at varying confidence levels. We find no evidence of either CO2 or SO2 in any of the spectra; we further show through a theoretical analysis that it is highly unlikely that these species are detectable in any 1-2.5 μm Galileo NIMS data.

Keywords: europa; jovian satellites; bayesian statistics; near infrared astronomy; surface ices; planetary surfaces; chemical abundances; radiative transfer simulations; spectroscopy
COol Companions ON Ultrawide orbiTS (COCONUTS). III. A Very Red L6 Benchmark Brown Dwarf around a Young M5 Dwarf

We present the third discovery from the COol Companions ON Ultrawide orbiTS (COCONUTS) program, the COCONUTS-3 system, composed of the young M5 primary star UCAC4 374-046899 and the very red L6 dwarf WISEA J081322.19-152203.2. These two objects have a projected separation of $61^{\prime\prime} $ (1891 au) and are physically associated given their common proper motions and estimated distances. The primary star, COCONUTS-3A, has a mass of 0.123 ± 0.006 M ⊙, and we estimate its age as 100 Myr to 1 Gyr based on its stellar activity (via Hα and X-ray emission), kinematics, and spectrophotometric properties. We derive its bulk metallicity as 0.21 ± 0.07 dex using empirical calibrations established by older and higher-gravity M dwarfs and find that this [Fe/H] could be slightly underestimated according to PHOENIX models given COCONUTS-3A's younger age. The companion, COCONUTS-3B, has a near-infrared spectral type of L6 ± 1 INT-G, and we infer physical properties of T eff = ${1362}_{-73}^{+48}$ K, $\mathrm{log}(g)$ = ${4.96}_{-0.34}^{+0.15}$ dex, $R\,=\,{1.03}_{-0.06}^{+0.12}$ R Jup, and $M\,=\,{39}_{-18}^{+11}$ M Jup using its bolometric luminosity, its host star's age, and hot-start evolution models. We construct cloudy atmospheric model spectra at the evolution-based physical parameters and compare them to COCONUTS-3B's spectrophotometry. We find that this companion possesses ample condensate clouds in its photosphere (f sed = 1) with the data-model discrepancies likely due to the models using an older version of the opacity database. Compared to field-age L6 dwarfs, COCONUTS-3B has fainter absolute magnitudes and a 120 K cooler T eff. Also, the J - K color of this companion is among the reddest for ultracool benchmarks with ages older than a few hundred megayears. COCONUTS-3 likely formed in the same fashion as stellar binaries given the companion-to-host mass ratio of 0.3 and represents a valuable benchmark to quantify the systematics of substellar model atmospheres.

Keywords: relativistic fluid dynamics; l dwarfs; substellar companion stars; m stars
3 μm Spectroscopic Survey of Near-Earth Asteroids

Near-Earth Asteroids (NEAs) are excellent laboratories for processes that affect airless body surfaces. S-complex (including V-type) NEAs were not expected to contain OH/H2O on their surfaces because they formed in the anhydrous regions of the solar system and their surface temperatures are high enough to remove these volatiles. However, a 3 μm feature typically indicative of OH/H2O was identified on other seemingly dry bodies in the inner solar system, raising the question of how widespread volatiles may be on NEAs. We observed 29 NEAs using both prism (0.7-2.52 μm) and LXD_short (1.67-4.2 μm) modes on SpeX on NASA's IRTF in order to accurately characterize asteroid spectral type and the 3 μm region. Eight of the observed NEAs have a 3 μm absorption feature at >1σ (three of which are present to >2σ), and they exhibit four identified band shape types. Possible sources for OH/H2O on these bodies include carbonaceous chondrite impacts and/or interactions with protons implanted by solar wind. Characteristics such as composition and aphelion appear to play an important role in the delivery and/or retention of OH/H2O, as all eight NEAs with an absorption feature are S-complex asteroids and six enter the main asteroid belt. Additionally, perihelion, size, albedo, and orbital period may play a minor role. Our observations determined that nominally anhydrous, inner solar system bodies, and therefore near-Earth space in general, contain more OH/H2O than previously expected. The identified trends should help predict which NEAs that have not yet been observed might contain OH/H2O on their surfaces.

Keywords: near-earth objects; spectroscopy; near infrared astronomy; asteroids; surveys; ground-based astronomy
The Global Magneto-ionic Medium Survey: A Faraday Depth Survey of the Northern Sky Covering 1280-1750 MHz

The Galactic interstellar medium hosts a significant magnetic field, which can be probed through the synchrotron emission produced from its interaction with relativistic electrons. Linearly polarized synchrotron emission is generated throughout the Galaxy and, at longer wavelengths, modified along nearly every path by Faraday rotation in the intervening magneto-ionic medium. Full characterization of the polarized emission requires wideband observations with many frequency channels. We have surveyed polarized radio emission from the Northern sky over the range 1280-1750 MHz, with channel width 236.8 kHz, using the John A. Galt Telescope (diameter 25.6 m) at the Dominion Radio Astrophysical Observatory, as part of the Global Magneto-Ionic Medium Survey. The survey covered 72% of the sky, decl. -30° to +87° at all R.A. The intensity scale was absolutely calibrated, based on the flux density and spectral index of Cygnus A. Polarization angle was calibrated using the extended polarized emission of the Fan Region. Data are presented as brightness temperatures with angular resolution 40'. Sensitivity in Stokes Q and U is 45 mK rms in a 1.18 MHz band. We have applied rotation measure synthesis to the data to obtain a Faraday depth cube of resolution 150 rad m-2 and sensitivity 3 mK rms of polarized intensity. Features in Faraday depth up to a width of 110 rad m-2 are represented. The maximum detectable Faraday depth is ±2 × 104 rad m-2. The survey data are available at the Canadian Astronomy Data Centre.

Keywords: polarimetry; polarimeters; spectropolarimetry; radio telescopes; calibration; interstellar magnetic fields; milky way magnetic fields
On the H I Content of MaNGA Major Merger Pairs

The role of H I content in galaxy interactions is still under debate. To study the H I content of galaxy pairs at different merging stages, we compile a sample of 66 major-merger galaxy pairs and 433 control galaxies from the Sloan Digital Sky Survey IV (SDSS-IV) MaNGA IFU survey. In this study, we adopt kinematic asymmetry as a new effective indicator to describe the merging stage of galaxy pairs. With archival data from the HI-MaNGA survey and new observations from the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we investigate the differences in H I gas fraction (f H I), star formation rate (SFR), and H I star formation efficiency (SFEH I) between the pair and control samples. Our results suggest that the H I gas fraction of major-merger pairs on average is marginally decreased by ~15% relative to isolated galaxies, implying mild H I depletion during galaxy interactions. Compared to isolated galaxies, pre-passage paired galaxies have similar f H I, SFR, and SFEH I, while pairs during the pericentric passage have weakly decreased f H I (-0.10 ± 0.05 dex), significantly enhanced SFR (0.42 ± 0.11 dex), and SFEH I (0.48 ± 0.12 dex). When approaching the apocenter, paired galaxies show marginally decreased f H I (-0.05 ± 0.04 dex), comparable SFR (0.04 ± 0.06 dex), and SFEH I (0.08 ± 0.08 dex). We propose that the marginally detected H I depletion may originate from the gas consumption in fueling the enhanced H2 reservoir of galaxy pairs. In addition, new FAST observations also reveal a H I absorber (N H I ~ 4.7 × 1021 cm-2), which may suggest gas infalling and the triggering of active galactic nuclei activity.

Keywords: galaxy interactions; galaxy pairs; galaxy mergers; interstellar atomic gas; star formation
Predicting the Spectroscopic Features of Galaxies by Applying Manifold Learning on Their Broadband Colors: Proof of Concept and Potential Applications for Euclid, Roman, and Rubin LSST

Entering the era of large-scale galaxy surveys, which will deliver unprecedented amounts of photometric and spectroscopic data, there is a growing need for more efficient, data-driven, and less model-dependent techniques to analyze the spectral energy distribution of galaxies. In this work, we demonstrate that by taking advantage of manifold learning approaches, we can estimate spectroscopic features of large samples of galaxies from their broadband photometry when spectroscopy is available only for a fraction of the sample. This will be done by applying the self-organizing map algorithm on broadband colors of galaxies and mapping partially available spectroscopic information into the trained maps. In this pilot study, we focus on estimating the 4000 Å break in a magnitude-limited sample of galaxies in the Cosmic Evolution Survey (COSMOS) field. We also examine this method to predict the Hδ A index given our available spectroscopic measurements. We use observed galaxy colors (u,g,r,i,z,Y,J,H), as well as spectroscopic measurements for a fraction of the sample from the LEGA-C and zCOSMOS spectroscopic surveys to estimate this feature for our parent photometric sample. We recover the D4000 feature for galaxies that only have broadband colors with uncertainties about twice the uncertainty of the employed spectroscopic surveys. Using these measurements, we observe a positive correlation between D4000 and the stellar mass of the galaxies in our sample with weaker D4000 features for higher-redshift galaxies at fixed stellar masses. These can be explained by the downsizing scenario for the formation of galaxies and the decrease in their specific star formation rate as well as the aging of their stellar populations over this time period.

Keywords: broad band photometry; spectroscopy; galaxy colors
Laboratory and Astronomical Detection of the SiP Radical (X2Π i ): More Circumstellar Phosphorus

The millimeter-wave spectrum of the SiP radical (X2Πi) has been measured in the laboratory for the first time using direct-absorption methods. SiP was created by the reaction of phosphorus vapor and SiH4 in argon in an AC discharge. Fifteen rotational transitions (J + 1 ← J) were measured for SiP in the Ω = 3/2 ladder in the frequency range 151-533 GHz, and rotational, lambda doubling, and phosphorus hyperfine constants determined. Based on the laboratory measurements, SiP was detected in the circumstellar shell of IRC+10216, using the Submillimeter Telescope and the 12 m antenna of the Arizona Radio Observatory at 1 mm and 2 mm, respectively. Eight transitions of SiP were searched: four were completely obscured by stronger features, two were uncontaminated (J = 13.5 → 12.5 and 16.5 → 15.5), and two were partially blended with other lines (J = 8.5 → 7.5 and 17.5 → 16.5). The SiP line profiles were broader than expected for IRC+10216, consistent with the hyperfine splitting. From non-LTE radiative transfer modeling, SiP was found to have a shell distribution with a radius ~300 R *, and an abundance, relative to H2, of f ~ 2 × 10-9. From additional modeling, abundances of 7 × 10-9 and 9 × 10-10 were determined for CP and PN, respectively, both located in shells at 550-650 R *. SiP may be formed from grain destruction, which liberates both phosphorus and silicon into the gas phase, and then is channeled into other P-bearing molecules such as PN and CP.

Keywords: astrochemistry; circumstellar envelopes; molecular spectroscopy; evolved stars; chemical abundances; interstellar molecules; asymptotic giant branch stars
Energetics of Solar Coronal Bright Points

The several-million-degree, low-density quiet solar corona requires a total energy-loss flux of about 3 × 105 erg cm-2 s-1. Solar coronal bright points (CBPs) are ubiquitous in the quiet Sun. They may release magnetic energy to heat the solar corona, but their contribution to the energy flux has not been determined yet. We used an automatic identification and tracking method for CBPs, which was developed based on the support vector machine classifier and Zernike moments of extreme ultraviolet (EUV) observations from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. We applied a spatial synthesis differential emission measure method and a Vertical-Current Approximation Nonlinear Force-Free Field technique to extract the thermal and magnetic energetics of the CBPs, respectively. By analyzing 7.5 yr (within the solar cycle 24) of AIA observations, we show that the average thermal energy and magnetic free energy of 140,000 CBPs are positively correlated with sunspots. However, the number of CBPs and sunspots are highly anti-correlated. We calculate a total energy-loss flux (sum of the radiative and conductive loss flux) of about (4.84 ± 1.60) × 103 erg cm-2 s-1 for the system of CBPs. Therefore, it is about 1.61% ± 0.53% of the total energy-loss flux of quiet corona. By extending the distribution of the magnetic Poynting flux and energy-loss flux for CBPs to nanoflares, the total magnetic Poynting flux and total energy-loss flux are obtained to be in the range of 1.48 × 105 to 1.57 × 106 and 3.86 × 104 to 2.35 × 105 erg cm-2 s-1, respectively.

Keywords: solar corona; solar coronal heating; solar coronal lines; quiet solar corona; solar magnetic fields; solar magnetic reconnection
E+A Galaxy Candidates in and around the Leo Cluster

E+A galaxies are post-starburst galaxies that have undergone a recent, complete quenching of star formation. We have analyzed a color-constrained sample of galaxies from the Sloan Digital Sky Survey within a 77'5 radius of the center of the Leo cluster of galaxies (A1367; J2000 11:44:36.5 + 19:45:32) within 3000 km s-1 of Leo's redshift of z = 0.022 to identify and survey the E+A galaxy candidates in the cluster. Within this sample, we classified 52 of these galaxies as E+A galaxy candidates based on their spectral shapes, u-r color, lack of Hα emission, and higher-order hydrogen Balmer absorption. We further subdivide this group into "blue" and "green" E+A candidates. Our results show that the E+A galaxy candidates are distributed across the northwest and southeast subclusters of Leo, possibly as a result of merging between the two subclusters.

Keywords: e+a galaxies; post-starburst galaxies; galaxy quenching; galaxy evolution; abell clusters
JWST Near-infrared Spectroscopy of the Lucy Jupiter Trojan Flyby Targets: Evidence for OH Absorption, Aliphatic Organics, and CO2

We present observations obtained with the Near Infrared Spectrograph on JWST of the five Jupiter Trojans that will be visited by the Lucy spacecraft—the Patroclus–Menoetius binary, Eurybates, Orus, Leucus, and Polymele. The measured 1.7–5.3 μm reflectance spectra, which provide increased wavelength coverage, spatial resolution, and signal-to-noise ratio over previous ground-based spectroscopy, reveal several distinct absorption features. We detect a broad OH band centered at 3 μm that is most prominent on the less-red objects Eurybates, Patroclus–Menoetius, and Polymele. An additional absorption feature at 3.3–3.6 μm, indicative of aliphatic organics, is systematically deeper on the red objects Orus and Leucus. The collisional fragment Eurybates is unique in displaying an absorption band at 4.25 μm that we attribute to bound or trapped CO2. Comparisons with other solar system small bodies reveal broad similarities in the 2.7–3.6 μm bands with analogous features on Centaurs, Kuiper Belt objects (KBOs), and the active asteroid 238P. In the context of recent solar system evolution models, which posit that the Trojans initially formed in the outer solar system, the significant attenuation of the 2.7–3.6 μm absorption features on Trojans relative to KBOs may be the result of secondary thermal processing of the Trojans' surfaces at the higher temperatures of the Jupiter region. The CO2 band manifested on the surface of Eurybates suggests that CO2 may be a major constituent in the bulk composition of Trojans, but resides in the subsurface or deeper interior and is largely obscured by refractory material that formed from the thermophysical processes that were activated during their inward migration.

Keywords: jupiter trojans; surface composition; james webb space telescope
On the Cosmic Evolution of AGN Obscuration and the X-Ray Luminosity Function: XMM-Newton and Chandra Spectral Analysis of the 31.3 deg2 Stripe 82X

We present X-ray spectral analysis of XMM-Newton and Chandra observations in the 31.3 deg2 Stripe-82X (S82X) field. Of the 6181 unique X-ray sources in this field, we analyze a sample of 2937 candidate active galactic nuclei (AGNs) with solid redshifts and sufficient counts determined by simulations. Our results show an observed population with median values of spectral index ${\rm{\Gamma }}={1.94}_{-0.39}^{+0.31}$ , column density log $\,{N}_{{\rm{H}}}/{\mathrm{cm}}^{-2}={20.7}_{-0.5}^{+1.2}$ and intrinsic, de-absorbed, 2-10 keV luminosity log $\,{L}_{{\rm{X}}}/\mathrm{erg}\,\ {{\rm{s}}}^{-1}={44.0}_{-1.0}^{+0.7}$ , in the redshift range 0-4. We derive the intrinsic, model-independent, fraction of AGNs that are obscured ( $22\leqslant \mathrm{log}\,{N}_{{\rm{H}}}/{\mathrm{cm}}^{-2}\lt 24$ ), finding a significant increase in the obscured AGN fraction with redshift and a decline with increasing luminosity. The average obscured AGN fraction is 57% ± 4% for log L X/erg s-1 > 43. This work constrains the AGN obscuration and spectral shape of the still uncertain high-luminosity and high-redshift regimes (log L X/erg s-1 > 45.5, z > 3), where the obscured AGN fraction rises to 64% ± 12%. We report a luminosity and density evolution of the X-ray luminosity function, with obscured AGNs dominating at all luminosities at z > 2, and unobscured sources prevailing at log L X/erg s-1 > 45 at lower redshifts. Our results agree with the evolutionary models in which the bulk of AGN activity is triggered by gas-rich environments and in a downsizing scenario. Moreover, the black hole accretion density (BHAD) is found to evolve similarly to the star formation rate density, confirming the coevolution between AGN and host galaxy, but suggesting different timescales in their growing history. The derived BHAD evolution shows that Compton-thick AGNs contribute to the accretion history of AGNs as much as all other AGN populations combined.

Keywords: x-ray surveys; active galactic nuclei; galaxy evolution; x-ray active galactic nuclei; cosmology; cosmological evolution; cosmological models; active galaxies