Sazuna/UAT_keywords huggingface dataset:
Searching for Extragalactic Exoplanetary Systems: The Curious Case of BD+20 2457. Planets and their host stars carry a long-term memory of their origin in their chemical compositions. Thus, identifying planets formed in different environments improves our understating of planetary formation. Although restricted to detecting exoplanets within the solar vicinity, we might be able to detect planetary systems that formed in small external galaxies and later merged with the Milky Way. In fact, Gaia data have unequivocally shown that the Galaxy underwent several significant minor mergers during its first billion years of formation. The stellar debris of one of these mergers, Gaia-Enceladus (GE), is thought to have built up most of the stellar halo in the solar neighborhood. In this Letter, we investigate the origin of known planet-host stars combining data from the NASA Exoplanet Archive with Gaia EDR3 and large-scale spectroscopic surveys. We adopt a kinematic criterion and identify 42 stars associated with the Milky Way's thick disk and one halo star. The only halo star identified, BD+20 2457, known to harbor two exoplanets, moves on a retrograde and highly eccentric orbit. Its chemical abundance pattern situates the star at the border between the thick disk, the old halo, and accreted populations. Given its orbital parameters and chemical properties, we suggest that BD+20 2457 is likely formed in the protodisk of the Galaxy, but we do not exclude the possibility of the star belonging to the debris of GE. Finally, we estimate a minimum age and mass limit for the star, which has implications for its planetary system and will be tested with future Transiting Exoplanet Survey Satellite observations.

Keywords: Milky Way stellar halo, Galaxy dynamics, Galaxy kinematics, Exoplanets
Tracking the Evolution of Lithium in Giants Using Asteroseismology: Super-Li-rich Stars Are Almost Exclusively Young Red-clump Stars. We report novel observational evidence on the evolutionary status of lithium-rich giant stars by combining asteroseismic and lithium abundance data. Comparing observations and models of the asteroseismic gravity-mode period spacing ΔΠ1, we find that super-Li-rich giants (SLRs, A(Li) &gt; 3.2 dex) are almost exclusively young red-clump (RC) stars. Depending on the exact phase of evolution, which requires more data to refine, SLR stars are either (i) less than ∼2 Myr or (ii) less than ∼40 Myr past the main core helium flash (CHeF). Our observations set a strong upper limit for the time of the inferred Li-enrichment phase of &lt;40 Myr post-CHeF, lending support to the idea that lithium is produced around the time of the CHeF. In contrast, the more evolved RC stars (&gt;40 Myr post-CHeF) generally have low lithium abundances (A(Li) &lt;1.0 dex). Between the young, super-Li-rich phase, and the mostly old, Li-poor RC phase, there is an average reduction of lithium by about 3 orders of magnitude. This Li destruction may occur rapidly. We find the situation to be less clear with stars having Li abundances between the two extremes of super-Li-rich and Li-poor. This group, the "Li-rich" stars (3.2 &gt; A(Li) &gt; 1.0 dex), shows a wide range of evolutionary states.

Keywords: Stellar abundances, Asteroseismology, Low mass stars, Stellar interiors
Probing Multiple Populations of Compact Binaries with Third-generation Gravitational-wave Detectors. Third-generation (3G) gravitational-wave detectors will be able to observe binary black hole mergers (BBHs) up to a redshift of ∼30. This gives unprecedented access to the formation and evolution of BBHs throughout cosmic history. In this paper, we consider three subpopulations of BBHs originating from the different evolutionary channels: isolated formation in galactic fields, dynamical formation in globular clusters, and mergers of black holes formed from Population III (Pop III) stars at very high redshift. Using input from population synthesis analyses, we create 2 months of simulated data of a network of 3G detectors made of two Cosmic Explorers and one Einstein Telescope consisting of ∼16,000 field and cluster BBHs, as well as ∼400 Pop III BBHs. First, we show how one can use a nonparametric model to infer the existence and characteristics of a primary and secondary peak in the merger rate distribution as a function of redshift. In particular, the location and height of the secondary peak around z ≈ 12, arising from the merger of Pop III remnants, can be constrained at the ${ \mathcal O }(10 \% )$ level (95% credible interval). Then we perform a modeled analysis using phenomenological templates for the merger rates of the three subpopulations and extract the branching ratios and characteristic parameters of the merger rate densities of the individual formation channels. With this modeled method, the uncertainty on the measurement of the fraction of Pop III BBHs can be improved to ≲10%, while the ratio between field and cluster BBHs can be measured with an uncertainty of ∼100%.

Keywords: Gravitational wave astronomy, Gravitational waves, Gravitational wave sources
Precovery Observations Confirm the Capture Time of Asteroid 2020 CD3 as Earth's Minimoon. Asteroid 2020 CD3 was discovered on 2020 February 15 by the Catalina Sky Survey while it was temporarily captured in a geocentric orbit before escaping Earth's Hill sphere on 2020 March 7. We searched archival images and found precoveries of 2020 CD3 from the Dark Energy Camera and Catalina Sky survey. The Dark Energy Camera images yielded three observations on 2019 January 17, while the Catalina Sky Survey images yielded four observations on 2019 January 24 from the Mt. Lemmon telescope and four observations on 2018 May 9 from the Mt. Bigelow telescope. These precovery observations allowed us to refine the orbit of 2020 CD3 and determine that it was captured in a geocentric orbit on 2017 September 15 after a close approach to the Moon at a distance of 11,974 ± 10 km. We analyzed the trajectory of 2020 CD3 to look for potential Earth impacts within the next 100 years and find a ≳1% probability of an impact between 2061 and 2120 depending on nongravitational force model assumptions. The small size of 2020 CD3, about 1 to 2 m, makes any potential impact harmless.

Keywords: Near-Earth objects, Asteroids
Population Properties of Compact Objects from the Second LIGO-Virgo Gravitational-Wave Transient Catalog. We report on the population of 47 compact binary mergers detected with a false-alarm rate of &lt; $1\,{\mathrm{yr}}^{-1}$ in the second LIGO-Virgo Gravitational-Wave Transient Catalog. We observe several characteristics of the merging binary black hole (BBH) population not discernible until now. First, the primary mass spectrum contains structure beyond a power law with a sharp high-mass cutoff; it is more consistent with a broken power law with a break at ${39.7}_{-9.1}^{+20.3}\,\,{M}_{\odot }$ or a power law with a Gaussian feature peaking at ${33.1}_{-5.6}^{+4.0}\,\,{M}_{\odot }$ (90% credible interval). While the primary mass distribution must extend to $\sim 65\,{M}_{\odot }$ or beyond, only ${2.9}_{-1.7}^{+3.5} \% $ of systems have primary masses greater than $45\,{M}_{\odot }$ . Second, we find that a fraction of BBH systems have component spins misaligned with the orbital angular momentum, giving rise to precession of the orbital plane. Moreover, $12$ %- $44$ % of BBH systems have spins tilted by more than 90°, giving rise to a negative effective inspiral spin parameter, ${\chi }_{\mathrm{eff}}$ . Under the assumption that such systems can only be formed by dynamical interactions, we infer that between 25% and 93% of BBHs with nonvanishing $| {\chi }_{\mathrm{eff}}| \gt 0.01$ are dynamically assembled. Third, we estimate merger rates, finding ${{ \mathcal R }}_{\mathrm{BBH}}={23.9}_{-8.6}^{+14.3}\,\,{\mathrm{Gpc}}^{-3}\,{\mathrm{yr}}^{-1}$ for BBHs and ${{ \mathcal R }}_{\mathrm{BNS}}={320}_{-240}^{+490}\,\,{\mathrm{Gpc}}^{-3}\,{\mathrm{yr}}^{-1}$ for binary neutron stars. We find that the BBH rate likely increases with redshift ( $85 \% $ credibility) but not faster than the star formation rate ( $86 \% $ credibility). Additionally, we examine recent exceptional events in the context of our population models, finding that the asymmetric masses of GW190412 and the high component masses of GW190521 are consistent with our models, but the low secondary mass of GW190814 makes it an outlier.

Keywords: Bayesian statistics, Massive stars, Stellar mass black holes, Gravitational waves, Compact objects, Astrophysical black holes
A Unified Model of Solar Prominence Formation. Several mechanisms have been proposed to account for the formation of solar prominences or filaments, among which direct injection and evaporation-condensation models are the two most popular ones. In the direct injection model, cold plasma is ejected from the chromosphere into the corona along magnetic field lines; in the evaporation-condensation model, the cold chromospheric plasma is heated to over a million degrees and is evaporated into the corona, where the accumulated plasma finally reaches thermal instability or nonequilibrium so as to condensate to cold prominences. In this paper, we try to unify the two mechanisms: The essence of filament formation is the localized heating in the chromosphere. If the heating happens in the lower chromosphere, the enhanced gas pressure pushes the cold plasma in the upper chromosphere to move up to the corona, such a process is manifested as the direct injection model. If the heating happens in the upper chromosphere, the local plasma is heated to 1-2 million degrees, and is evaporated into the corona. Later, the plasma condensates to form a prominence. Such a process is manifested as the evaporation-condensation model. With radiative hydrodynamic simulations we confirmed that the two widely accepted formation mechanisms of solar prominences can really be unified in such a single framework. A particular case is also found where both injection and evaporation-condensation processes occur together.

Keywords: Hydrodynamical simulations, Solar chromosphere, Solar filaments, Solar prominences
The Tarda Meteorite: A Window into the Formation of D-type Asteroids. Dynamic models of solar system evolution suggest that D-type asteroids formed beyond Saturn's orbit and represent invaluable witnesses of the prevailing conditions in the outer solar system. Here, we report a comprehensive petrographic and isotopic characterization of the carbonaceous chondrite Tarda, a recent fall recovered in the Moroccan Sahara. We show that Tarda shares strong similarities with the D-type-derived chondrite Tagish Lake, implying that Tarda represents a rare sample of D-type asteroids. Both Tarda and Tagish Lake are characterized by the presence of rare 16O-rich chondrules and chondrule fragments, high C/H ratios, and enrichments in deuterium, 15N, and 13C. By combining our results with literature data on carbonaceous chondrites related to C-type asteroids, we show that the outer solar system 4.56 Gy ago was characterized by large-scale oxygen isotopic homogeneities in (i) the water-ice grains accreted by asteroids and (ii) the gas controlling the formation of FeO-poor chondrules. Conversely, the zone in which D-type asteroids accreted was significantly enriched in deuterium relative to the formation regions of C-type asteroids, features likely inherited from unprocessed, D-rich, molecular-cloud materials.

Keywords: Isotopic abundances, Carbonaceous chondrites, Asteroids, Trans-Neptunian objects
The Effect of Core Formation on Surface Composition and Planetary Habitability. The melt productivity of a differentiated planet's mantle is primarily controlled by its iron content, which is itself approximated by the planet's core mass fraction (CMF). Here we show that estimates of an exoplanet's CMF allows robust predictions of the thickness, composition, and mineralogy of the derivative crust. These predicted crustal compositions allow constraints to be placed on volatile cycling between surface and the deep planetary interior, with implications for the evolution of habitable planetary surfaces. Planets with large, terrestrial-like CMFs (≥0.32) will exhibit thin crusts that are inefficient at transporting surface water and other volatiles into the underlying mantle. By contrast, rocky planets with smaller CMFs (≤0.24) and higher, Mars-like, mantle iron contents will develop thick crusts capable of stabilizing hydrous minerals, which can effectively sequester volatiles into planetary interiors and act to remove surface water over timescales relevant to evolution. The extent of core formation has profound consequences for the subsequent planetary surface environment and may provide additional constraints in the hunt for habitable, Earth-like exoplanets.

Keywords: Extrasolar rocky planets, Planetary cores, Habitable planets
Identification of an [α/Fe]—Enhanced Thick Disk Component in an Edge-on Milky Way Analog. The Milky Way disk consists of two prominent components—a thick, alpha-rich, low-metallicity component and a thin, metal-rich, low-alpha component. External galaxies have been shown to contain thin- and thick-disk components, but whether distinct components in the [α/Fe]-[Z/H] plane exist in other Milky Way-like galaxies is not yet known. We present Very Large Telescope (VLT)—Multi Unit Spectroscopic Explorer (MUSE) observations of UGC 10738, a nearby, edge-on Milky Way-like galaxy. We demonstrate through stellar population synthesis model fitting that UGC 10738 contains alpha-rich and alpha-poor stellar populations with similar spatial distributions to the same components in the Milky Way. We discuss how the finding that external galaxies also contain chemically distinct disk components may act as a significant constraint on the formation of the Milky Way's own thin and thick disk.

Keywords: Galaxy stellar content, Milky Way evolution, Galaxy evolution, Disk galaxies
The Life Cycle of Magnetars: A Novel Approach to Estimate Their Ages. Anomalous X-ray pulsars and soft gamma repeaters are slowly rotating, young, and isolated neutron stars exhibiting sporadic outbursts and high X-ray quiescent luminosities. They are believed to be powered by ultrastrong magnetic fields, B ∼ 1014-1015 G, associated with "magnetars." In the peculiar case of SGR 0418+5729, timing parameters imply a dipolar B-field of 6.1 × 1012 G. This discovery has challenged the traditional picture of magnetars in terms of B-field strengths, evolutionary stages, and ages. Here we provide a novel approach to estimate a magnetar's age by considering the self-consistent time evolution of a plasma-filled oblique pulsar with the state-of-the-art magnetospheric particle acceleration gaps. The rotational period of magnetars increases over time due to angular momentum extraction by gravitational-wave radiations, magnetic dipole radiations, and particle winds. These torques also change the obliquity angle between the magnetic and rotation axes. For SGR 0418+5729, we obtain a dipolar B-field of 1.0 × 1014 G, and a realistic age of ∼18 kyr, consistent within the magnetar paradigm.

Keywords: Neutron stars, Magnetars, Pulsars
The Imprint of Large-scale Structure on the Ultrahigh-energy Cosmic-Ray Sky. Ultrahigh-energy cosmic rays (UHECRs) are atomic nuclei from space with vastly higher energies than any other particles ever observed. Their origin and chemical composition remain a mystery. As we show here, the large and intermediate angular scale anisotropies observed by the Pierre Auger Observatory are a powerful tool for understanding the origin of UHECRs. Without specifying any particular production mechanism but only postulating that the source distribution follows the matter distribution of the local universe, a good accounting of the magnitude, direction, and energy dependence of the dipole anisotropy at energies above 8 × 1018 eV is obtained after taking into account the impact of energy losses during propagation (the "GZK horizon"), diffusion in the extragalactic magnetic field, and deflections in the Galactic magnetic field (GMF). This is a major step toward the long-standing hope of using UHECR anisotropies to constrain UHECR composition and magnetic fields. The observed dipole anisotropy is incompatible with a pure proton composition in this scenario. With a more accurate treatment of energy losses, it should be possible to further constrain the cosmic-ray composition and properties of the extragalactic magnetic field, self-consistently improve the GMF model, and potentially expose individual UHECR sources.

Keywords: Milky Way magnetic fields, Cosmic rays, Large-scale structure of the universe, Cosmic ray astronomy, Cosmic anisotropy, Cosmic ray sources, Ultra-high-energy cosmic radiation, Extragalactic magnetic fields
Solar Origin of Compressive Alfvénic Spikes/Kinks as Observed by Parker Solar Probe. The solar wind is found by the Parker Solar Probe to be abundant with Alfvénic velocity spikes and magnetic field kinks. Temperature enhancement is another remarkable feature associated with the Alfvénic spikes. How the prototype of these coincident phenomena is generated intermittently in the source region is an important and wide-ranging subject. Here we propose a new model introducing guide-field discontinuity into the interchange magnetic reconnection between open funnels and closed loops with different magnetic helicities. The modified interchange reconnection model not only can accelerate jet flows from the newly opening closed loop but also can excite and launch Alfvénic wave pulses along the newly reconnected and post-reconnected open flux tubes. We find that the modeling results can reproduce the following observational features: (1) Alfvén disturbance is pulsive in time and asymmetric in space; (2) Alfvénic pulse is compressive with temperature enhancement and density variation inside the pulse. We point out that three physical processes co-happening with Alfvén wave propagation can be responsible for the temperature enhancement: (a) convection of heated jet flow plasmas (decrease in density), (b) propagation of compressive slow-mode waves (increase in density), and (c) conduction of heat flux (weak change in density). We also suggest that the radial nonlinear evolution of the Alfvénic pulses should be taken into account to explain the formation of magnetic switchback geometry.

Keywords: Solar atmosphere, Solar wind, Alfven waves, Solar magnetic reconnection
The Atomic Gas Mass of Green Pea Galaxies. We have used the Arecibo Telescope and the Green Bank Telescope (GBT) to carry out a deep search for HI 21 cm emission from a large sample of "Green Pea" galaxies, yielding 19 detections, and 21 upper limits on the HI mass. We obtain HI masses of MHI ≈ (4-300) × 108 M⊙ for the detections, with a median HI mass of ≈ 2.6 × 109 M⊙; for the non-detections, the median 3σ upper limit on the HI mass is ≈ 5.5 × 108 M⊙. These are the first estimates of the atomic gas content of Green Pea galaxies. We find that the HI-to-stellar mass ratio in Green Peas is consistent with trends identified in star-forming galaxies in the local universe. However, the median HI depletion timescale in Green Peas is ≈0.6 Gyr, an order of magnitude lower than that obtained in local star-forming galaxies. This implies that Green Peas consume their atomic gas on very short timescales. A significant fraction of the Green Peas of our sample lie ≳0.6 dex (2σ) above the local MHI-MB relation, suggesting recent gas accretion. Further, ≈30% of the Green Peas are more than ±2σ deviant from this relation, suggesting possible bimodality in the Green Pea population. We obtain a low HI 21 cm detection rate in the Green Peas with the highest O32 ≡ [O III]λ5007/[O II]λ3727 luminosity ratios, O32 &gt; 10, consistent with the high expected Lyman-continuum leakage from these galaxies.

Keywords: Galaxy masses, Galaxies, H I line emission
Evidence for TiO in the Atmosphere of the Hot Jupiter HAT-P-65 b. We present the low-resolution transmission spectra of the puffy hot Jupiter HAT-P-65b (0.53 MJup, 1.89 RJup, Teq = 1930 K), based on two transits observed using the OSIRIS spectrograph on the 10.4 m Gran Telescopio CANARIAS. The transmission spectra of the two nights are consistent, covering the wavelength range 517-938 nm and consisting of mostly 5 nm spectral bins. We perform equilibrium-chemistry spectral retrieval analyses on the jointly fitted transmission spectrum and obtain an equilibrium temperature of ${1645}_{-244}^{+255}$ K and a cloud coverage of ${36}_{-17}^{+23}$ %, revealing a relatively clear planetary atmosphere. Based on free-chemistry retrieval, we report strong evidence for titanium oxide (TiO). Additional individual analyses in each night reveal weak-to-moderate evidence for TiO in both nights, but moderate evidence for Na or VO only in one of the nights. Future high-resolution Doppler spectroscopy as well as emission observations will help confirm the presence of TiO and constrain its role in shaping the vertical thermal structure of HAT-P-65b's atmosphere.

Keywords: Exoplanet atmospheric composition , Exoplanets, Hot Jupiters, Transmission spectroscopy, Exoplanet atmospheres
Discovery of the Pure Polycyclic Aromatic Hydrocarbon Indene (c-C9H8) with GOTHAM Observations of TMC-1. Polycyclic aromatic hydrocarbons (PAHs) have long been invoked in the study of interstellar and protostellar sources, but the unambiguous identification of any individual PAH has proven elusive until very recently. As a result, the formation mechanisms for this important class of molecules remain poorly constrained. Here we report the first interstellar detection of a pure hydrocarbon PAH, indene (C9H8), as part of the GBT Observations of TMC-1: Hunting for Aromatic Molecules (GOTHAM) survey. This detection provides a new avenue for chemical inquiry, complementing the existing detections of CN-functionalized aromatic molecules. From fitting the GOTHAM observations, indene is found to be the most abundant organic ring detected in TMC-1 to date. And from astrochemical modeling with nautilus, the observed abundance is greater than the model's prediction by several orders of magnitude, suggesting that current formation pathways in astrochemical models are incomplete. The detection of indene in relatively high abundance implies related species such as cyanoindene, cyclopentadiene, toluene, and styrene may be detectable in dark clouds.

Keywords: Interstellar molecules, Polycyclic aromatic hydrocarbons, Dark interstellar clouds, Astrochemistry
The Emergence of Structure in the Binary Black Hole Mass Distribution. We use the gravitational wave signals from binary black hole merger events observed by LIGO and Virgo to reconstruct the underlying mass and spin distributions of the population of merging black holes. We reconstruct the population using the mixture model framework VAMANA using observations in GWTC-2 occurring during the first two observing runs and the first half of the third run (O1, O2, and O3a). Our analysis identifies a structure in the chirp mass distribution of the observed population. Specifically, we identify peaks in the chirp mass distribution at 8, 14, 26, and 45 M⊙ and a complementary structure in the component mass distribution with an excess of black holes at masses of 9, 16, 45, and 57 M⊙. Intriguingly, for both the distributions, the location of subsequent peaks are separated by a factor of around two and there is a lack of mergers with chirp masses of 10-12 M⊙. The appearance of multiple peaks is a feature of a hierarchical merger scenario when, due to a gap in the black hole mass spectrum, a pile-up occurs at the first peak followed by mergers of lower mass black holes to hierarchically produce higher mass black holes. However, cross-generation merger peaks and observations with high spins are also predicted to occur in such a scenario that we are not currently observing. The results presented are limited in measurement accuracy due to small numbers of observations but if corroborated by future gravitational wave observations these features have far-reaching implications.

Keywords: Gravitational wave astronomy, Gravitational waves, Gravitational wave sources