adsabs/SciX_UAT_keywords huggingface dataset:
Ninety-seven Eclipsing Quadruple Star Candidates Discovered in TESS Full-frame Images

We present a catalog of 97 uniformly vetted candidates for quadruple star systems. The candidates were identified in TESS full-frame image data from sectors 1-42 through a combination of machine-learning techniques and visual examination, with major contributions from a dedicated group of citizen scientists. All targets exhibit two sets of eclipses with two different periods, both of which pass photocenter tests confirming that the eclipses are on target. This catalog outlines the statistical properties of the sample, nearly doubles the number of known multiply eclipsing quadruple systems, and provides the basis for detailed future studies of individual systems. Several important discoveries have already resulted from this effort, including the first sextuply eclipsing sextuple stellar system and the first transiting circumbinary planet detected from one sector of TESS data.

Keywords: multiple stars; eclipsing binary stars
GASP XXIV. The History of Abruptly Quenched Galaxies in Clusters

The study of cluster post-starburst galaxies gives useful insights on the physical processes quenching the star formation in the most massive environments. Exploiting the Multi Unit Spectroscopic Explorer data of the GAs Stripping Phenomena in galaxies project, we characterize the quenching history of eight local cluster galaxies that were selected for not showing emission lines in their fiber spectra. We inspect the integrated colors, the Hβ rest-frame equivalent widths (EW), star-formation histories (SFHs), and luminosity-weighted age (LWA) maps finding no signs of current star formation throughout the disks of these early-spiral/S0 galaxies. All of them have been passive for at least 20 Myr, but their SF declined on different timescales. In most of them, the outskirts reached undetectable SFRs before the inner regions ("outside-in quenching"). Our sample includes three post-star-forming galaxies, two passive galaxies, and three galaxies with intermediate properties. The first population shows blue colors, deep Hβ in absorption (EW ≫ 2.8 Å), young ages (8.8 < log(LWA (yr)) < 9.2). Two of these galaxies show signs of a central SF enhancement before quenching. Passive galaxies have instead red colors, EW(Hβ) < 2.8 Å, ages in the range 9.2 < log(LWA (yr)) < 10. Finally, the other galaxies are most likely in transition between a post-star-forming and passive phase, as they quenched in an intermediate epoch and have not lost all of the star-forming features yet. The outside-in quenching, the morphology, and kinematics of the stellar component, along with the position of these galaxies within massive clusters (σcl = 550-950 km s-1) point to a scenario in which ram pressure stripping has removed the gas, leading to quenching. Only the three most massive galaxies might alternatively have entered the clusters already quenched. These galaxies are therefore at the final stage of the rapid evolution galaxies undergo when they enter the cluster environment.

Keywords: galaxy formation; galaxy clusters; galaxy evolution; e+a galaxies; galaxies; star formation
Effects of Orbital Eccentricity and IMF Cone Angle on the Dimensions of Mercury's Magnetosphere

We investigate the influence of orbital eccentricity and interplanetary magnetic field (IMF) direction on the dimensions of Mercury's magnetosphere using four Earth years of data collected by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft. The variations in magnetopause subsolar distance, flank distance, and tail radius are compared to determine the global dimensions and compressibility of the magnetosphere. As Mercury moves from perihelion (aphelion) to aphelion (perihelion) its magnetosphere expands (contracts) globally by ∼15% on average. After mapping all of the magnetopause crossings to a fixed radial distance from the Sun, we find that IMF cone angle changes lead to reconfigurations of the magnetosphere of comparable magnitude to radial solar distance effects. Furthermore, the magnetosphere is found to expand globally under the quasi-radial IMF, while contracting under the quasi-perpendicular conditions. A new Mercury magnetopause model parameterized by the heliocentric distance and IMF cone angle was constructed. Unlike Earth, the model gives a closed magnetopause for the nightside in most cases, and its flaring decreases with the contraction of the magnetosphere. The results demonstrate the highly variable reconfigurations of Mercury's magnetosphere under its extreme environmental conditions.

Keywords: planetary magnetospheres; solar-planetary interactions; mercury (planet); solar wind; interplanetary magnetic fields; solar magnetic reconnection
Inferring the Solar Meridional Circulation Flow Profile by Applying Bayesian Methods to Time-Distance Helioseismology

Mapping the large-scale subsurface plasma flow profile within the Sun has been attempted using various methods for several decades. One such flow in particular is the meridional circulation, for which numerous studies have been published. However, such studies often show disagreement in structure. In an effort to constrain the flow profile from the data, a Bayesian Markov chain Monte Carlo framework has been developed to take advantage of the advances in computing power that allow for the efficient exploration of high-dimensional parameter spaces. This study utilizes helioseismic travel-time difference data covering a span of 21 years and a parameterized model of the meridional circulation to find the most likely flow profiles. Tests were carried out on artificial data to determine the ability of this method to recover expected solar-like flow profiles, as well as a few extreme cases. We find that this method is capable of recovering the input flows of both single- and double-cell flow structures. Some inversion results indicate potential differences in meridional circulation between the two solar cycles in terms of both magnitude and morphology, in particular in the mid-convection zone. Of these, the most likely solutions show that solar cycle 23 has a large single-celled profile, while cycle 24 shows weaker flows in general and hints toward a double-celled structure.

Keywords: solar meridional circulation; solar interior; the sun; solar physics; solar cycle; helioseismology
Exploring the "L-σ" Relation of H II Galaxies and Giant Extragalactic H II Regions Acting as Standard Candles

Cosmological applications of H II galaxies and giant extragalactic H II regions (GEHRs) to construct the Hubble diagram at high redshifts require knowledge of the "L-σ" relation of the standard candles used. In this paper, we study the properties of a large sample of 156 sources (25 high-z H II galaxies, 107 local H II galaxies, and 24 GEHRs) compiled by Terlevich et al. Using the cosmological distances reconstructed through two new cosmology-independent methods, we investigate the correlation between the Hβ emission-line luminosity L and the ionized gas velocity dispersion σ. The method is based on non-parametric reconstruction using the measurements of Hubble parameters from cosmic clocks, as well as the simulated data of gravitational waves from the third-generation gravitational wave detector (the Einstein Telescope, ET), which can be considered as standard sirens. Assuming the relation between emission-line luminosity and ionized gas velocity dispersion, $\mathrm{log}L({\rm{H}}\beta )=\alpha \mathrm{log}\sigma ({\rm{H}}\beta )+\kappa $ , we find that the full sample provides a tight constraint on the correlation parameters. However, similar analysis done on three different subsamples seems to support the scheme of treating H II galaxies and GEHRs with distinct strategies. Using the corrected "L-σ" relation for the H II observational sample beyond the current reach of Type Ia supernovae, we obtain values of the matter density parameter, Ωm = 0.314 ± 0.054 (calibrated with standard clocks) and Ωm = 0.311 ± 0.049 (calibrated with standard sirens), in the spatially flat ΛCDM cosmology.

Keywords: cosmological parameters; h ii regions; standard candles
Stellar Occultations in the Era of Data Mining and Modern Regression Models: Using Gaussian Processes to Analyze Light Curves and Improve Predictions

Gaussian process (GP) regression is a nonparametric Bayesian approach that has been used successfully in various astronomical domains, especially in time-domain astronomy. The most common applications are the smoothing of data for interpolation and the detection of periodicities. The ability to create unbiased data-driven models without a predefined physical model can be a major advantage over conventional regression methods. Prior knowledge can be included by setting boundary conditions or constraining hyperparameter values, while unknown hyperparameters are optimized during the conditioning of the model. We have adapted and transformed previous approaches of GP regression and introduce three new applications for this regression method, especially in the context of stellar occultations: the modeling of occultation light curves, the correction of public JPL ephemerides of minor planets based on publicly available image data of the Zwicky Transient Facility, and the detection of natural satellites. We used data from observations of stellar occultations to validate the models and achieved promising results in all cases, and thus we confirmed the flexibility of GP regression models. Considering various existing use cases in addition to our novel applications, GP regression can be used to model diverse data sets addressing a wide range of problems. The accuracy of the model depends on the input data and on the set boundary conditions. Generally, high-quality data allow the usage of loose boundary conditions, while low-quality data require more restrictive boundary conditions to avoid overfitting.

Keywords: stellar occultation; gaussian processes regression; astronomy data modeling; ephemerides
TESS Data for Asteroseismology: Timing Verification

The Transiting Exoplanet Survey Satellite (TESS) is NASA's latest space telescope dedicated to the discovery of transiting exoplanets around nearby stars. Besides the main goal of the mission, asteroseismology is an important secondary goal and very relevant for the high-quality time series that TESS will make during its two-year all-sky survey. Using TESS for asteroseismology introduces strong timing requirements, especially for coherent oscillators. Although the internal clock on board TESS is precise in its own time, it might have a constant drift. Thus, it will need calibration, or else offsets might inadvertently be introduced. Here, we present simultaneous ground- and space-based observations of primary eclipses of several binary systems in the Southern ecliptic hemisphere, used to verify the reliability of the TESS timestamps. From 12 contemporaneous TESS/ground observations, we determined a time offset equal to 5.8 ± 2.5 s, in the sense that the barycentric time measured by TESS is ahead of real time. The offset is consistent with zero at the 2.3σ level. In addition, we used 405 individually measured mid-eclipse times of 26 eclipsing binary stars observed solely by TESS in order to test the existence of a potential drift with a monotonic growth (or decay) affecting the observations of all stars. We find a drift corresponding to σdrift = 0.009 ± 0.015 s day-1. We find that the measured offset is of a size that will not become an issue for comparing ground-based and space data for coherent oscillations for most of the targets observed with TESS. * Based on observations made at the Argentinian Complejo Astronómico El Leoncito (CASLEO).

Keywords: eclipsing binary minima timing method; eclipsing binary stars; asteroseismology; observational astronomy
The Galaxy Starburst/Main-sequence Bimodality over Five Decades in Stellar Mass at z ≈ 3-6.5

We study the relation between stellar mass (M *) and star formation rate (SFR) for star-forming galaxies over approximately five decades in stellar mass ( $5.5\ \lesssim \ {\mathrm{log}}_{10}({M}_{* }/{M}_{\odot })\lesssim 10.5$ ) at z ≈ 3-6.5. This unprecedented coverage has been possible thanks to the joint analysis of blank non-lensed fields (COSMOS/SMUVS) and cluster lensing fields (Hubble Frontier Fields) that allow us to reach very low stellar masses. Previous works have revealed the existence of a clear bimodality in the SFR-M * plane with a star formation Main Sequence and a starburst cloud at z ≈ 4-5. Here we show that this bimodality extends to all star-forming galaxies and is valid in the whole redshift range z ≈ 3-6.5. We find that starbursts constitute at least ≈20% of all star-forming galaxies with M * ≳ 109 M ⊙ at these redshifts and reach a peak of 40% at z = 4-5. More importantly, 60%-90% of the total SFR budget at these redshifts is contained in starburst galaxies, indicating that the starburst mode of star formation is dominant at high redshifts. Almost all the low stellar mass starbursts with ${\mathrm{log}}_{10}({M}_{* }/{M}_{\odot })\lesssim 8.5$ have ages comparable to the typical timescales of a starburst event, suggesting that these galaxies are being caught in the process of formation. Interestingly, galaxy formation models fail to predict the starburst/main-sequence bimodality and starbursts overall, suggesting that the starburst phenomenon may be driven by physical processes occurring at smaller scales than those probed by these models.

Keywords: galaxy evolution; galaxy formation; starburst galaxies; high-redshift galaxies
Jet Structure and Burst Environment of GRB 221009A

We conducted a comprehensive investigation of the brightest-of-all-time GRB 221009A, using new insights from very high-energy (VHE) observations from LHAASO and a complete multiwavelength afterglow data set. Through data fitting, we imposed constraints on the jet structure, radiation mechanisms, and burst environment of GRB 221009A. Our findings reveal a structured jet morphology characterized by a core+wing configuration. A smooth transition of energy within the jet takes place between the core and wing, but with a discontinuity in the bulk Lorentz factor. The jet structure differs from both the case of the short GRB 170817A and the results of numerical simulations for long-duration bursts. The VHE emission can be explained by the forward shock synchrotron self-Compton radiation of the core component, but requiring a distinctive transition of the burst environment from uniform to wind-like, suggesting the presence of complex pre-burst mass ejection processes. The low-energy multiwavelength afterglow is mainly governed by the synchrotron radiation from the forward and reverse shocks of the wing component. Our analysis indicates a magnetization factor of 5 for the wing component. Additionally, by comparing the forward shock parameters of the core and wing components, we find a potential correlation between the electron acceleration efficiency and both the Lorentz factor of the shock and the magnetic field equipartition factor. We discuss the significance of our findings, potential interpretations, and remaining issues.

Keywords: gamma-ray bursts
Radial Segregation between Red Giant Populations in the Globular Cluster NGC 3201: Tentative Role of Varying Mass among the Progenitors

In the globular cluster NGC 3201, we study subpopulations (SPs) of red giants (RGs) distinguished by their characteristics. In its central part, we make use of multicolor Hubble Space Telescope (HST) photometry coupled with spectroscopy of RGs spread out over a larger cluster face. In the color index CI $=\,({m}_{{\rm{F}}275{\rm{W}}}-{m}_{{\rm{F}}336{\rm{W}}})\,-({m}_{{\rm{F}}336{\rm{W}}}-{m}_{{\rm{F}}439{\rm{W}}})$ , RGs commonly referred to as first generation, SPI, are separated from the counterparts of the second generation, SPII. The latter are more concentrated than the former at a confidence level of P = 93%, within the field covered by the HST photometry. Their minor portion (∼28%, SPIIm) located in the middle of the δCI range spanned across the split RG branch relative to the splitting edge is more centrally concentrated at a higher confidence level of 96%. We found, from the [Na/Fe]-δCI plot for RGs in common between the photometry and spectroscopy, that SPI and SPII are mostly overlapped within 0.0 < [Na/Fe] < 0.3. RGs with [Na/Fe] < 0.0 (mostly SPI) keep their lower concentration to the cluster center over larger radial distance as compared to SPII RGs with [Na/Fe] > 0.3 at a confidence level of P = 88%. It is increased up to 95% if a restriction on [O/Fe] is imposed. The obtained result, particularly in the central part, is a clue that SPIIm RGs are the descendants of more massive progenitors. Of these RGs approximately one-third probably originate from recent (within the past 1.5 Gyr) blue stragglers with MBS > 1.1M⊙, and the other two-thirds could be accounted for by older collision products of primordial MS stars.

Keywords: stellar populations; population ii stars; star clusters; globular star clusters; stellar mergers; stellar evolution; blue straggler stars; red giant stars
RR Lyrae Stars in Stellar Streams with Gaia: The Escapers

We attempt to identify RR Lyrae (RRL) stars in stellar streams that might have escaped from seven globular clusters (GCs) based on proper motions, distances, color-magnitude diagrams, and other properties extracted from the Gaia Early Data Release 3 (EDR3) database. Specifically, we cross-match two large RRL stars catalogs (from Gaia DR2 and Catalina Sky Survey) with each other and with the EDR3 database, and we end up with a sample of ~150,000 unique RRL stars. We calculate distances to RRL stars using the MG-[Fe/H] and MV-[Fe/H] absolute magnitude-metallicity relations and adopt [Fe/H] values for the GCs from different spectroscopic studies. We also constrain our search to areas where stellar streams associated with GCs were previously suggested or identified in other studies. We identify 24 RRL stars that might have escaped from the following seven GCs: Palomar 13 (Pal 13), NGC 6341 (M92), NGC 5904 (M5), NGC 5466, NGC 1261, NGC 288, and NGC 1851. We list our findings in Table 2.

Keywords: galaxy accretion; galaxy evolution; galaxy structure; galaxy tails; galaxy tides; milky way evolution; milky way formation; milky way dynamics; globular star clusters; beta lyrae stars; rr lyrae variable stars
The Extended [C II] under Construction? Observation of the Brightest High-z Lensed Star-forming Galaxy at z = 6.2

We present results of [C II] 158 μm emission line observations, and report the spectroscopic redshift confirmation of a strongly lensed (μ ~ 20) star-forming galaxy, MACS0308-zD1 at z = 6.2078 ± 0.0002. The [C II] emission line is detected with a signal-to-noise ratio >6 within the rest-frame UV-bright clump of the lensed galaxy (zD1.1) and exhibits multiple velocity components; the narrow [C II] has a velocity full width half maximum (FWHM) of 110 ± 20 km s-1, while broader [C II] is seen with an FWHM of 230 ± 50 km s-1. The broader [C II] component is blueshifted (-80 ± 20 km s-1) with respect to the narrow [C II] component, and has a morphology that extends beyond the UV-bright clump. We find that, while the narrow [C II] emission is most likely associated with zD1.1, the broader component is possibly associated with a physically distinct gas component from zD1.1 (e.g., outflowing or inflowing gas). Based on the nondetection of λ 158μm dust continuum, we find that MACS0308-zD1's star formation activity occurs in a dust-free environment indicated by a strong upper limit of infrared luminosity ≲9 × 108 L ⊙. Targeting this strongly lensed faint galaxy for follow-up Atacama Large Millimeter/submillimeter Array and JWST observations will be crucial to characterize the details of typical galaxy growth in the early Universe.

Keywords: high-redshift galaxies; galaxy evolution; galaxy formation; gravitational lensing
Afterglow Light Curves of Nonrelativistic Ejecta Mass in a Stratified Circumstellar Medium

We present the afterglow light curves produced by the deceleration of a nonrelativistic ejecta mass in a stratified circumstellar medium with a density profile n(r) ∝ r-k with k = 0, 1, 1.5, 2, and 2.5. Once the ejecta mass is launched with equivalent kinetic energy parameterized by E(>β) ∝ β-α (where β is the ejecta velocity) and propagates into the surrounding circumstellar medium, it first moves with constant velocity (the free-coasting phase), and later it decelerates (the Sedov-Taylor expansion). We present the predicted synchrotron and synchrotron self-Compton light curves during the free-coasting phase and the subsequent Sedov-Taylor expansion. In particular cases, we show the corresponding light curves generated by the deceleration of several ejecta masses with different velocities launched during the coalescence of binary compact objects and the core collapse of dying massive stars, which will contribute at distinct timescales, frequencies, and intensities. Finally, using the multiwavelength observations and upper limits collected by a large campaign of orbiting satellites and ground telescopes, we constrain the parameter space of both the kilonova (KN) afterglow in GW170817 and the possibly generated KN afterglow in S190814bv. Further observations on timescales of years post-merger are needed to derive tighter constraints.

Keywords: gamma-ray bursts; gravitational wave astronomy; non-thermal radiation sources; compact binary stars
Reduced Atmospheres of Post-impact Worlds: The Early Earth

Impacts may have had a significant effect on the atmospheric chemistry of the early Earth. Reduced phases in the impactor (e.g., metallic iron) can reduce the planet's H2O inventory to produce massive atmospheres rich in H2. While previous studies have focused on the interactions between the impactor and atmosphere in such scenarios, we investigate two further effects: (1) the distribution of the impactor's iron inventory during impact between the target interior, target atmosphere, and escaping the target; and (2) interactions between the post-impact atmosphere and the impact-generated melt phase. We find that these two effects can potentially counterbalance each other, with the melt-atmosphere interactions acting to restore reducing power to the atmosphere that was initially accreted by the melt phase. For a ~1022 kg impactor, when the iron accreted by the melt phase is fully available to reduce this melt, we find an equilibrium atmosphere with H2 column density ~104 moles cm-2 (pH2 ~ 120 bars, X H2 ~ 0.77), consistent with previous estimates. However, when the iron is not available to reduce the melt (e.g., sinking out in large diameter blobs), we find significantly less H2 (7 × 102 - 5 × 103 moles cm-2, pH2 ≲ 60 bars, X H2 ≲ 0.41). These lower H2 abundances are sufficiently high that species important to prebiotic chemistry can form (e.g., NH3, HCN), but sufficiently low that the greenhouse heating effects associated with highly reducing atmospheres, which are problematic to such chemistry, are suppressed. The manner in which iron is accreted by the impact-generated melt phase is critical in determining the reducing power of the atmosphere and resolidified melt pool in the aftermath of impact.

Keywords: planetary science; pre-biotic astrochemistry; planetary atmospheres; impact phenomena