Sazuna/UAT_keywords huggingface dataset:
Chemical abundances of neutron capture elements in the Milky Way. Understanding the formation, structure and evolution of the Milky Way is one of the main open questions in modern astronomy. The Galaxy is made up of chemical elements originated from Big Bang to stellar nucleosynthesis. Among them, there are some that stand out for their special nucleosynthesis: they are the so-called neutron-capture elements. Although they are the majority among the elements, they only represent a small amount of the global composition of the Universe. However, it is in this small percentage where the keys of the evolution of the Galaxy are found. Among these keys are the chemical abundances. Based on 506 stars of the Solar neighbourhood observed at the Molėtai Astronomical Observatory and 62 open clusters from the Gaia ESO Survey, this thesis tried to answer some of the main questions in this field. Through its 6 chapters, the thesis deals with extremely important topics such as the temporal and spatial abundance gradients of neutron-capture elements in the Galactic thin and thick discs, as well as their application to calculate the ages of stars. Among its most significant results, the thesis provides new insights on s-processes indicators and the astrophysical origin of the r-process. For the first time a comprehensive analysis of the use of chemical clocks in the thick disc is made and the radial variations of calibrated chemical clocks are investigated in depth using a reliable sample of open clusters, indeed the largest used for this purpose.

Keywords: Galaxy chemical evolution, Nucleosynthesis, Milky Way Galaxy, Chemical abundances
Testing Algorithms for Identifying Source Confusion in the H I-MaNGA Survey. Astronomical observations of neutral atomic hydrogen (H I) are an important tracer of several key processes of galaxy evolution, but face significant difficulties with terrestrial telescopes. Among these is source confusion, or the inability to distinguish between emission from multiple nearby sources separated by distances smaller than the telescope's spatial resolution. Confusion can compromise the data for the primary target if the flux from the secondary galaxy is sufficient. This paper presents an assessment of the confusion-flagging methods of the H I-MaNGA survey, using higher-resolution H I data from the Westorbork Synthesis Radio Telescope-Apertif survey. We find that removing potentially confused observations using a confusion probability metric-calculated from the relationship between galaxy color, surface brightness, and H I content-successfully eliminates all significantly confused observations in our sample, although roughly half of the eliminated observations are not significantly confused.

Keywords: Radio telescopes, H I line emission
Light Curve Test of GRB 200716C as a Gravitationally Lensed Echo. A gravitational lens can imprint distinct features on the light curve of a gamma-ray burst (GRB). Most prominently, when creating multiple images, the light curves for all images should be identical, within a scale factor in amplitude. For GRB images that are bright enough to have significant counts in multiple time bins, the similarity of the light curves can be assessed with a straightforward χ 2 test. In response to a recent claim that the two pulses in GRB 200716C are lensed images of the same pulse, such a χ 2 test was computed. The test indicated that the likelihood that the two pulses are images of the same parent pulse is less than 0.218%, differing at about the 3.1σ confidence level. Therefore, under the given assumptions, GRB 200716C is not a compelling example of gravitational lensing.

Keywords: Gamma-ray bursts, Gravitational lensing
Modifying the Free Energy in Skye. The Skye Equation of State (EOS) is built on top of automatic differentiation machinery. This makes it straightforward to modify, because all the requisite partial derivatives of the Helmholtz free energy are computed automatically via operator overloading. Here we demonstrate this advantage by implementing a new prescription for the anharmonic free energy of a crystalline one-component plasma. Apart from boilerplate and variable declarations, only 7 new lines of code were needed.

Keywords: Stellar physics, Plasma physics, Astronomy software, Stellar evolution
Time Evolution of the CMB Quadrupole. I show that the quadrupole of the Cosmic Microwave Background (CMB) evolves more rapidly than previously expected, as a result of the acceleration of the Sun toward the Galactic center. The acceleration, measured most recently by Gaia EDR3, implies a fractional change in the quadrupole of ~10-9 per year, an order of magnitude larger than expected from the evolution in the last scattering surface of the CMB.

Keywords: Cosmic microwave background radiation
A Brightness Classification Boundary in the Kuiper Belt Population. The Kuiper Belt contains a large number of minor bodies that collectively constrain the dynamical history of the solar system. These bodies are often classified into distinct populations. This note identifies a well-defined boundary (at H-magnitude = 5.65) that separates bright (large) objects from dimmer (smaller) objects. The probability that the two sub-samples are drawn from the same underlying distribution is p ~ 10-15. The larger bodies (estimated radius R ≳ 125 km) are dynamically hot, as measured by their locations in the e- $\sin i$ plane, and likely represent an implanted population. The smaller bodies (R ≲ 125 km) are dynamically colder and are likely to be primordial. The bright/large/hot population currently contains ~200 members, including all ~50 dwarf planet candidates in the Kuiper Belt.

Keywords: Small Solar System bodies, Solar system, Kuiper belt
Demonstrating the Concept of Parallax with James Webb Space Telescope. We measured the parallax of the James Webb Space Telescope based on near simultaneous observations using the Lulin One-meter Telescope and the GROWTH India Telescope, separated at a distance of ~4214 km. This serves a great demonstration for the concept of parallax commonly taught in introductory astronomy courses.

Keywords: Parallax, Ground telescopes
The Line Variability of 78 Vir (A2p SrCrEu) in the Far-ultraviolet. Line variations are studied in the far-ultraviolet spectra of 78 Vir collected with International Ultraviolet Explorer at phases of far-UV maximum and at phases of far-UV minimum. The far-UV spectrum of 78 Vir is populated with low-excitation transitions of light elements and iron-peak elements. The low excitation C I and N I lines are stronger at phases of far-UV minimum. Carbon appears to be underabundant and aluminum very underabundant in the atmosphere of 78 Vir. The lines of Si I and Si II are stronger at phases of far-UV minimum. Many lines which strengthen at phases of far-UV minimum are due to low-excitation lines of Fe II and Cr II which suggests that both iron and chromium are unevenly distributed over the surface of 78 Vir.

Keywords: Ap stars, Chemically peculiar stars
Quasi-periodic Dimming of the  130 Myr-old Debris-Disk Hosting Star HD 240779 is not Persistent. Quasi-periodic (1.5 days) dimming (by circumstellar dust) of the 135 Myr-old AB Doradus moving group member HD 240779 was detected in photometry by TESS in late 2018. Similar observations two years later show no such signal, and ground-based photometry indicate that the signal was absent in late 2019. This suggests that the source of the dust did not survive long after 2018, e.g., it was a disrupted planetesimal, or that dust production by the body is episodic, analogous to the "evaporating" planets detected by Kepler.

Keywords: Circumstellar dust, Young stellar objects, Debris disks, Planetesimals
The Search for a Counterpart to NuSTAR J053449+2126.0. (ATel #15171) have recently reported the discovery of an X-ray source, NuSTAR J053449+2126.0, during a calibration observation which took place on 2020 April 25. We scan the Zwicky Transient Facility alerts and archival photometry to determine the nature of the source. Palomar Gattini-IR is searched as well. We identify no obvious counterpart candidate. Follow-up X-ray and optical studies are needed to determine the true counterpart.

Keywords: X-ray astronomy, X-ray identification, Time domain astronomy
Yonder: A Python Package for Data Denoising and Reconstruction. We present a standalone implementation of a data-deconvolution method based on singular value decomposition. The tool is written in python and packaged in the open-source yonder package. yonder receives as input two matrices, one for the data and another for the errors, and outputs a denoised version of the original dataset. In this Research Note, we briefly describe the methodology and show a demonstration of the yonder on a simulated dataset.

Keywords: Astrostatistics techniques, Astronomy data analysis, Astronomy software
The Far UV Variability of τ Her (HD 147394) Recorded by IUE. Evidence is presented that the far-ultraviolet flux of τ Her recorded by the International Ultraviolet Explorer is variable in a series of six spectra taken consecutively over 4 hr and 45 minutes The centroids of the resonance lines of O I, C II and Si II are blueshifted in several spectra and resume their original positions over a timescale of 3 hr 5 minutes. The FUV flux also varies over the same timescale. The far-ultraviolet variability is discussed in light of the recent TESS lightcurve observed for τ Her.

Keywords: B stars
Low-resolution Optical Spectroscopy of Recently Discovered Accreting-only Symbiotic Star THA 15-31. Recently, the discovery and characterization of a new accreting-only symbiotic star THA 15-31 was presented. Motivated by the suggestion that the optical spectrum of the star might show the emission lines with higher ionization potential in comparison with previously studied epochs, we have obtained a low-resolution spectrum of this target. The spectrum does not reveal the presence of suggested He II emission lines. Moreover, the near-UV excess seems to be even less prominent now in comparison with the previous observations, suggesting a decrease in mass transfer and accretion rate. The search for He II emission lines should be repeated when the accretion rate is higher.

Keywords: Symbiotic binary stars, Emission line stars, Spectroscopy, Red giant stars
Gravitational Redshift for Wide Binaries in Gaia eDR3. The Doppler effect is commonly used to infer the velocity difference between stars based on the relative shifts in the rest-frame wavelengths of their spectral features. In wide binaries, the difference in gravitational redshift from the surfaces of the constituent stars with distinct compactness dominates at separations ≳10-2 pc. I suggest that this effect became apparent for wide pairs in the Gaia eDR3 catalog but was incorrectly interpreted as a possible modification of Newtonian gravity in the internal kinematics of very wide binaries.

Keywords: Binary stars
The Equilibrium Temperature of Planets on Eccentric Orbits: Time Scales and Averages. From estimates of the near-surface heat capacity of planets it is shown that the thermal timescale is larger than the orbital period in the presence of a global ocean that is well-mixed to a depth of 100 m, or of an atmosphere with a pressure of several tens of bars. As a consequence, the temperature fluctuations of such planets on eccentric orbits are damped. The average temperature should be calculated by taking the temporal mean of the irradiation over an orbit, which increases with $1/\sqrt{1-{e}^{2}}$ . This conclusion is independent of the orbital distance and valid for Sun-like stars; the damping is even stronger for low-mass main sequence hosts.

Keywords: Exoplanet dynamics, Exoplanet atmospheric variability, Planetary climates
Approximating Stellar Metallicity Using Photometric Machine Learning. Stellar metallicity is an important metric in analyzing stellar evolution. Measuring metallicity (e.g., [Fe/H]) usually requires spectroscopic data, but difficulties associated with gathering spectra for distant objects severely reduces the number of stars for which metallicity can be calculated. The Sloan Expedition for Galactic Understanding and Exploration (SEGUE) spectroscopic surveys are one of the most abundant public-sources of objects with spectra. Despite cataloging over 106 objects, the SEGUE data makes up only 0.4% of the data in SDSS photometric surveys. To overcome the limited spectra, this machine-learning method can approximate [Fe/H] from the 5 SDSS photometric filters with a root-mean-square-error (RMSE) of 0.277 dex. The RMSE from this method is similar to the scatter expected in [Fe/H] measurements from low-resolution spectra. Therefore, this method achieves similar accuracy to low-resolution spectra but can be applied to a few orders of magnitude more stars than what the current spectroscopic surveys allow.

Keywords: Photometric systems, Astronomy software, Random Forests, Metallicity, Stellar evolution
NGC 1605 is not a Binary Cluster. The open star cluster NGC 1605 has recently been reported to in fact consist of two clusters (one intermediate-aged and one old) that merged via a flyby capture. Here we show that Gaia data do not support this scenario. We also report the serendipitous discovery of a new open cluster, Can Batlló 1, with a similar age and distance.

Keywords: Astrostatistics, Clustering, Astrometry, Open star clusters, Milky Way evolution
Report on Three Stellar Occultations by the Excited Kuiper Belt Object 2002 MS4.. We report on three stellar occultation events by the Kuiper Belt object 2002 MS4, observed using a 300 mm telescope on Anarchist Mountain, BC, Canada. Using the three events we have determined chord diameters of (810 ± 70) km, (630 ± 140) km, and (780 ± 70) km. All of these diameters are consistent with those reported from previous occultation events. Based on these data we estimate that 2002 MS4 is at least 810 ± 70 km in diameter These events also provide high-precision sky positions for 2002 MS4 at the exact time of the occultation, which can be used to refine the orbital ephemeris of this target, improving predictions of future events. All data and processing outputs described in this Research Note can be retrieved from: 10.11570/22.0001

Keywords: Stellar occultation, Occultation, Classical Kuiper belt objects, Trans-Neptunian objects
A Parameterized Model for Differential Galaxy Counts at Any Wavelength. Certain astronomy problems, such as the probabilistic cross-matching algorithms of Wilson &amp; Naylor, require descriptions of galaxy counts as a function of brightness in many different filter sets, for which we often lack dedicated observations. With this motivation in mind, I present a simple model for calculating differential galaxy counts for an arbitrary bandpass or wavelength. The model uses a double Schechter function to describe the number density of galaxies as a function of absolute magnitude, including redshift-driven galaxy evolution, for both "blue" and "red" galaxy types. Collating previously derived values for the parameterization of the evolving Schechter function- ${M}_{0}^{* }$ , ${\phi }_{0}^{* }$ , P, Q, and α-I fit the dependencies of these parameters as a function of wavelength, allowing for the tabulation of differential galaxy counts in a new filter for which observations are unavailable. Finally, I briefly compare the model with some differential galaxy counts obtained from the literature.

Keywords: Galaxy photometry, Galaxy luminosities, Galaxy counts
A Murchison Widefield Array Search for Transmissions from the 4M Spacecraft, On Board the Chang'e 5-T1 Booster, Prior to its Predicted Collision with the Moon. Using the Murchison Widefield Array we searched for, and did not detect, 145.980 MHz transmissions from the 4M spacecraft attached to the Chang'e 5-T1 rocket booster. This object was predicted to collide with the Moon on 2022 March 4. We observed for a ten minutes period on 2022 March 1, achieving noise levels of ~4 Jy in a 10 kHz bandwidth. The expected signal level of a nominally operational transmitter would be ~7500 Jy. Thus, we conclude that the transmitter was inactive (or operating at less than 5 mW) in the days before the predicted impact with the Moon, which is reasonable given that the nominal mission life of 4M was approximately 8 days in late 2014. A detection would have allowed 4M and its host booster to be tracked to near the point of collision, which was not possible using optical telescopes due to the event occurring in daytime.

Keywords: The Moon
Eight-year Full-depth unWISE Coadds. We present deep, full-sky maps built from Wide-field Infrared Survey Explorer and NEOWISE exposures spanning the 2010 January-2020 December time period. These coadds, which incorporate roughly 8 yr of W1 (3.4 μm) and W2 (4.6 μm) imaging, are the deepest ever full-sky maps at wavelengths of 3-5 μm. Photometry based on these coadds will be a component of DESI Legacy Imaging Surveys DR10.

Keywords: Infrared astronomy, Astronomy data reduction
Seeing-Sorted Large Binocular Camera U-band Imaging of the Extended Groth Strip. We present the results of deep ground-based U-band imaging of the Extended Groth Strip (EGS) field, and the creation of a best resolution mosaic and a best depth mosaic following the seeing-sorted stacking method of Ashcraft et al. The analysis uses 324 images taken from 2012 March to 2021 June using the Large Binocular Camera. The best resolution mosaic includes the 16.4% of images with FWHM ≤ 0.″9, while the best depth mosaic includes the 73.5% of images with FWHM ≤ 1.″6. Each image's zero-point was matched to SDSS u, to account for transparency variations. Images with stellar ellipticity (1 - b/a) ≥ 0.08 were omitted. We find that the galaxy counts turn over at U AB ~ 25.75 mag in the best resolution mosaic and at ~26 mag in the best depth mosaic. The EGS field is the final UVCANDELS field analyzed using the seeing-sorted stacking method.

Keywords: Astronomical seeing, Ground telescopes, Astronomy data analysis, Ultraviolet surveys
The Young Binary DQ Tau Produces Another X-Ray Flare Near Periastron. This work is part of a multi-wavelength program to study the effects of X-ray/UV/optical stellar radiation on the chemistry of the circumbinary disk around the young high-eccentricity binary DQ Tau. ALMA observations for near/around 2021 December 5 periastron were postponed due to bad weather, but supporting Swift-XRT-UVOT TOO observations were successful. These Swift observations along with previous X-ray-optical-mm data show that DQ Tau keeps exhibiting powerful flares near periastron, offering a unique laboratory for studies of flare effects on the gas-phase ion chemistry in protoplanetary disks.

Keywords: Stellar x-ray flares, Spectroscopic binary stars, Pre-main sequence stars, Protoplanetary disks, Optical flares, X-ray stars
The White Dwarf Mass versus X-Ray Temperature Relationship of Dwarf Novae, Revisited. Most methods used to determine the white dwarf mass in non-magnetic cataclysmic variables are subject to large systematic errors. X-ray spectroscopy has the potential to enable mass estimation with a good accuracy, when calibrated against accurate and reliable values. This is now possible thanks to the work of Pala et al., who estimated the white dwarf masses for 43 cataclysmic variables relying in part on Gaia distances. In this research note we provide a brief update on the X-ray temperature versus white dwarf mass relationship using the X-ray spectroscopy results of Byckling et al. compared against the results of Pala et al., thereby putting the X-ray spectroscopy method on a securer footing.

Keywords: Cataclysmic variable stars
N-body Interactions will be Detectable in the HR-8799 System within 5 yr with VLTI-GRAVITY. While Keplerian orbits account for the majority of the astrometric motion of directly-imaged planets, perturbations due to N-body interactions allow us to directly constrain exoplanet masses in multiplanet systems. This has the potential to improve our understanding of massive directly-imaged planets, which nearly all currently have only model-dependent masses. The VLTI-GRAVITY instrument has demonstrated that interferometry can achieve 100x better astrometric precision than existing methods, a level of precision that makes detection of planet-planet interactions possible. In this study, we show that in the HR-8799 system, planet-planet deviations from currently used Keplerian approximations are expected to be up to one-quarter of a milliarcsecond within five years, which will make them detectable with VLTI-GRAVITY. Modeling of this system to directly constrain exoplanet masses will be crucial in order to make precise predictions.

Keywords: Exoplanet dynamics, Astrometric exoplanet detection, Exoplanet systems
On the Detectability of Post-common-envelope Binary Central Stars of Planetary Nebulae. Common envelope evolution is widely accepted as the principal shaping agent in the formation of aspherical planetary nebulae. However, only some 20% of planetary nebulae are found to host post-common-envelope binary central stars. To probe the detectability of post-common-envelope binary central stars, and their potential to evade detection, we simulate the light curves of an array of these systems varying their stellar and orbital parameters. We find that while binaries with late-type companions and/or long orbital periods will likely go undetected, they are unlikely to represent a large fraction of the overall post-common-envelope central star population.

Keywords: Planetary nebulae, Common envelope binary stars
Introducing MEGASIM: Multitudinous Earth Greek/Trojan Asteroid SIMulation. We announce the completion of two new Earth Trojan Asteroid (ETA) simulations. ETAs co-orbit the Sun with Earth and remain loosely bound to the fourth or fifth Lagrange points. To date, two ETAs have been detected (2010 TK7 and 2020 XL5); however, based on their orbits, these are likely temporary captures rather than members of a primordial population. The motivation for our simulations is multi-faceted: (1) the lack of a detected population despite literature claims of stability over the age of the solar system, (2) ETAs are important for both solar system science and planetary defense, and (3) the proximity of ETAs makes them prime candidates for space exploration missions. These simulations are of extremely high fidelity, large in number and long in simulation time. We will be releasing a series of papers based upon these simulations. *There is no indication that L4 Earth co-orbitals are referred to as a "Greek Camp" as in the Jupiter Trojan population. We merely preferred MEGASIM to METASIM.

Keywords: Earth trojans, Asteroid dynamics, Lagrangian points, N-body problem, Trojan asteroids, N-body simulations, Astronomical simulations
The Absence of Far UV Variability in the IUE Spectra of ξ Oct (HD 215573). The analysis of high resolution SWP spectra obtained through the large aperture with the International Ultraviolet Explorer reveals that the far-ultraviolet flux of ξ Oct did not vary. In particular, the flux remained stable in a series of seven spectra taken consecutively over 3 hr and 24 minutes. This time interval is much shorter than the 1.78 days rotational period proposed for this star from its TESS lightcurve, which could explain for the absence of variability in the FUV. The comparison of the STIS spectrum of ξ Oct in the range 1300-1340 Å with synthetic spectra computed for the fundamental parameters of ξ Oct and a solar composition allows the identification of the strongest absorption features in the far-ultraviolet as due to resonance lines of O I, Si II and C II.

Keywords: Pulsating variable stars
Visible and Infrared Spectroscopy of the Planetary Nebula M4-18. 0.47-2.45 μm spectroscopy is reported for the compact planetary nebula Minkowski 4-18 (PK146+07), filling some spectral gaps and presenting uniform and simultaneous observation of this entire spectral range. While the strongest features are the H I lines, the most prevalent are those of carbon, principally of C II, commensurate with the carbon rich, Wolf-Rayet nature of the exciting star.

Keywords: Planetary nebulae