Sazuna/UAT_keywords huggingface dataset:
Evolution of the Galaxy Merger Fraction in the CLAUDS+HSC-SSP Deep Fields. We estimate the evolution of the galaxy-galaxy merger fraction for M⋆ &gt; 1010.5M⊙ galaxies over 0.25 &lt; z &lt; 1 in the ∼18.6 deg2 deep CLAUDS+HSC-SSP surveys. We do this by training a Random Forest Classifier to identify merger candidates from a host of parametric morphological features, and then visually follow-up likely merger candidates to reach a high-purity, high-completeness merger sample. Correcting for redshift-dependent detection bias, we find that the merger fraction at z = 0 is 1.0% ± 0.2%, that the merger fraction evolves as (1 + z)2.3 ± 0.4, and that a typical massive galaxy has undergone ∼0.3 major mergers since z = 1. This pilot study illustrates the power of very deep ground-based imaging surveys combined with machine learning to detect and study mergers through the presence of faint, low surface brightness merger features out to at least z ∼ 1.

Keywords: Galaxy evolution, Galaxy interactions, Galaxy mergers
Explaining Neptune's Eccentricity. Early migration damped Neptune's eccentricity. Here, we assume that the damped value was much smaller than the value observed today, and show that the closest flyby of 0.1M star over 4.5Gyr in the field, at a distance of 103au would explain the value of Neptune's eccentricity observed today.

Keywords: Neptune
An Arecibo 327 MHz Search for Radio Pulsars and Bursts in the Dwarf Irregular Galaxies Leo A and T. We have conducted an Arecibo 327MHz search of two dwarf irregular galaxies in the Local Group, Leo A and T, for radio pulsars and single pulses from fast radio bursts and other giant pulse emitters. We detected no astrophysical signals in this search, and we estimate flux density limits on both periodic and burst emission. Our derived luminosity limits indicate that only the most luminous radio pulsars known in our Galaxy and in the Magellanic Clouds (MCs) would have been detectable in our search if they were at the distances of Leo A and T. Given the much smaller stellar mass content and star formation rates of Leo A and T compared to the Milky Way and the MCs, there are likely to be few (if any) extremely luminous pulsars in these galaxies. It is therefore not surprising that we detected no pulsars in our search.

Keywords: Dwarf irregular galaxies, Pulsars, Radio transient sources
ASASSN-21co: A Detached Eclipsing Binary with an 11.9 yr Period. We use ASAS V-band and ASAS-SN g-band observations to model the long-period detached eclipsing binary ASASSN-21co. ASAS observations show an eclipse of depth V0.6 mag in 2009 April. ASAS-SN g-band observations from 2021 March show an eclipse of similar duration and depth, suggesting an orbital period of 11.9 yr. We combine the g-band observations with additional BVRI photometry taken during the eclipse to model the eclipse using PHOEBE. We find that the system is best described by two M giants with a ratio of secondary radius to primary radius of 0.61. Optical spectra taken during the eclipse are consistent with at least one component of the binary being an M giant, and we find no temporal changes in the spectral features. The eclipse itself is asymmetric, showing an increase in brightness near mid-eclipse, likely due to rotational variability that is too low amplitude to be observed out-of-eclipse.

Keywords: Eclipsing binary stars, Sky surveys, Variable stars
The Fast Jitter in the OC Curves of Cataclysmic Variables Is Caused by Ordinary Flickering in the Light Curve that Randomly Shifts Each Eclipse Time. For Cataclysmic Variables (CVs), the record of many eclipse times (as presented in the traditional OC curves) often displays a small-amplitude fast jitter on timescales of under a few years, with these often being interpreted as physical effects such as from third bodies in the system (including planets), or from azimuthal movements of the Hot Spot around the edge of the accretion disk. Recently, with the new and excellent light curves from spacecraft missions TESS and Kepler, we can measure large numbers of eclipse times down to orbit-by-orbit timescales. For four representative CVs (DQ Her, U Sco, RW Tri, and UX UMa), I find that the OC jitter is constant from one-orbit-to-the-next out to eclipses separated by many years. This demonstrates that the jitter is not caused by physical effects on the orbit, nor by moving Hot Spots. This result was predicted for the expected jitter in eclipse times arising from the ubiquitous flickering in all CV light curves, where random flickers before/after eclipse minima will shift the measured eclipse times later/earlier than the true time of conjunction.

Keywords: Cataclysmic variable stars
Cloudy in the Microcalorimeter Era: Improved Energies for Si and S K Fluorescence Lines. The upcoming X-ray missions based on the microcalorimeter technology require exquisite precision in spectral simulation codes in order to match the unprecedented spectral resolution. In this work, we improve the fluorescence K energies for Si IIXI and S IIXIII in the code Cloudy. In particular, we provide here a patch to update the Cloudy fluorescence energy table, originally based on Kaastra &amp; Mewe, with the laboratory energies measured by Hell et al. The new Cloudy simulations were used to model the Chandra/HETG spectra of the High Mass X-ray Binary Vela X-1, showing a remarkable agreement and a dramatic improvement with respect to the current release version of Cloudy (C17.02).

Keywords: X-ray astronomy, X-ray binary stars, High energy astrophysics
Discovery of 13 New Orbital Periods for Classical Novae. I report new orbital periods (P) for 13 classical novae, based on light curves from TESS, AAVSO, and other public archives. These new nova periods now constitute nearly one-seventh of all known nova periods. Five of my systems have P&gt;1day, which doubles the number of such systems that must have evolved companion stars. (This is simply because ground-based time series have neither the coverage nor the stability required to discover these small-amplitude long periods.) V1016 Sgr has a rare P below the period gap, and suddenly becomes useful for current debates on evolution of novae. Five of the novae (FM Cir, V399 Del, V407 Lup, YZ Ret, and V549 Vel) have the orbital modulations in the tail of the eruption after the transition phase. Soon after the transition, YZ Ret shows a unique set of aperiodic diminishing oscillations, plus YZ Ret shows two highly significant transient periods, 1.1 and 4.5 longer than the orbital period, much like for the superhump phenomenon. I also report an optical 591.27465 s periodicity for V407 Lup, which is coherent and must be tied to the white dwarf spin period.

Keywords: Novae
Unveiling an Automated Modeling Method for S0 Galaxies. The objective of this study is to unveil an optimum and precise automated method to model S0 galaxies. Preliminary results of the study confirm that GALFIT-a two-dimensional image decomposition program-with a Sérsic profile can be used to model S0 galaxies. Since the input parameters affect the accuracy of the model, different combinations of parameters were tested to obtain the best-fit model. An automated GALFIT fitting process was developed using Python and Astropy module to increase the efficiency of the process. A sample of S0 galaxy images observed at the Kitt Peak National Observatory was used to test the precision of the implemented method. The accuracy of the created models was tested both visually and statistically. The new method will allow us to model a large sample of S0 galaxies accurately and determine their structure and properties.

Keywords: Lenticular galaxies
Analytical Solution of the Tidal Evolution of Eccentricity and Semimajor Axis for Close-in Planets. Tides can have significant effects on the orbital evolution of close-in planets. The evolution of eccentricity and semimajor axis is usually obtained by numerical integration of a set of coupled differential equations. We present here closed-form solutions to the evolution equations and derive from them an expression of the circularization time.

Keywords: Exoplanet dynamics, Exoplanet tides
Probable Detection of Water Ice in the Coma of the Inbound Long-period Comet C/2017 K2 (PanSTARRS). We present near-infrared reflectance spectra from 0.7 to 2.5 μm taken 2021 April 30 at the NASA Infrared Telescope Facility that show strong evidence for water ice within the coma of comet C/2017 K2 (PanSTARRS) at a heliocentric distance of RH = 6.488 au. This object has likely been active since ~35 au inbound and this provides a key piece of information to interpreting these early observations, understanding its dust properties, and assessing its overall volatile inventory and release mechanisms. A preliminary spectral model is best-fit with a volume fraction of ice of ~14% assuming that the refractory and volatile materials are mixed intimately. More sophisticated modeling and a deeper analysis of these data will be presented in a manuscript to be submitted later this year.

Keywords: Comets
The History and Origins of Directed Panspermia. Nobel laureate Frances Crick and renowned chemist Leslie Orgel are often credited with introducing the idea of "directed panspermia" in 1973. While they coined the term, the idea itself appeared in the scientific literature almost two decades earlier, and the first allusions can be traced back to 1930.

Keywords: Interdisciplinary astronomy, Astrobiology
Looking for Astrometric Signals below 20 m s<SUP>-1</SUP>: A Jupiter-mass Planet Signature in ɛ Eri. The USNO ground-based astrometric program URAT-Bright in combination with the Hipparcos mission epoch astrometry provides precise proper motions of a thousand bright stars in the southern hemisphere on a time basis of about 25 yr. Small but statistically significant differences between these proper motions and Gaia EDR3 data can reveal long-period exoplanets similar to Jupiter in the nearest star systems. The presence of such a planet orbiting the magnetically active dwarf ɛ Eri is confirmed from both URAT-Hipparcos-EDR3 data and Hipparcos-EDR3 data with a corresponding projected velocity of (+5, +8) and (+6, +13) m s-1, respectively. These signals are formally significant at a 0.989 and 1.0 confidence. We conclude that the newest astrometric results confirm the existence of a long-period exoplanet orbiting ɛ Eri, which was marginally detected from precision radial velocity measurements some 20 yr ago.

Keywords: Astrometric exoplanet detection, Proper motions
OW Hydrae: A Newly Discovered SB2 Algol in a Triple Star, from DAO Spectrograms. Evidence is presented that the detached Algol system OW Hya is a double-lined spectroscopic binary (SB2). The components appear to be closely similar to each other, which is contradicted by the failure so far to detect the secondary eclipse. A sizeable asymmetry in the Mg II λ4481 Å line is discussed. The interstellar line of Ca II-K line is present, and the primary star appears to be a late-B giant. OW Hya is the short-period pair of the interferometric triple star, CHR 175, which appears to be hierarchical.

Keywords: Binary stars, Interferometric binary stars, Spectroscopic binary stars, Detached binary stars, Eclipsing binary stars, Trinary stars
TESS as a Low-surface-brightness Observatory: Cutouts from Wide-area Coadded Images. We present a mosaic of those co-added Full Frame Images acquired by the TESS satellite that had been released in 2020 April. The mosaic shows substantial stray light over the sky. Yet over spatial scales of a few degrees, the background appears uniform. This result indicates that TESS has considerable potential as a Low Surface Brightness Observatory. The co-added images are freely available as a High Level Science Product (HLSP) at MAST and accessible through a Jupyter Notebook.

Keywords: Computational astronomy, Astronomy software, Diffuse radiation, Cloud computing, Computational methods, Low surface brightness galaxies
YMCA-1: A New Remote Star Cluster of the Milky Way?. We report the possible discovery of a new stellar system (YMCA-1), identified during a search for small scale overdensities in the photometric data of the YMCA survey. The object's projected position lies on the periphery of the Large Magellanic Cloud about 13° apart from its center. The most likely interpretation of its color-magnitude diagram, as well as of its integrated properties, is that YMCA-1 may be an old and remote star cluster of the Milky Way at a distance of 100 kpc from the Galactic center. If this scenario could be confirmed, then the cluster would be significantly fainter and more compact than most of the known star clusters residing in the extreme outskirts of the Galactic halo, but quite similar to Laevens 3. However, much deeper photometry is needed to firmly establish the actual nature of the cluster, and the distance to the system. * This work is based on INAF-VST guaranteed observing time under ESO program: 0104.D-0427(A).

Keywords: Surveys, Milky Way stellar halo, Hertzsprung Russell diagram, Magellanic Clouds, Star clusters
The Detailed Light-curve Evolution of V1674 Her (Nova Her 2021). We report high-cadence photometry of the ultra-fast (t2 ~ 1.2 days) nova V1674 Her during its rise to maximum light (V ~ 6.3) and the beginning of its subsequent decline. These observations from Evryscope and the Mount Laguna Observatory All-Sky Camera reveal a plateau in the pre-maximum light curve at g ~ 14 (~8 mag below peak) that lasted for at least three hours. Similar features (so-called pre-maximum halts) have been observed in some novae near maximum light, but to our knowledge the detection of a plateau in the light curve ~8 mag below peak is unprecedented.

Keywords: Light curves, Time domain astronomy, Classical novae
No Rotational Variability in C/2014 UN271 (Bernardinelli-Bernstein) at 23.8 au and 21.1 au as Seen by TESS. The recent discovery of a hundred-kilometer-scale comet, C/2014 UN271 (Bernardinelli-Bernstein), has provoked interest in the activity displayed by such a large body inbound from the Oort cloud. We examine the serendipitous observation of UN271 in long-cadence imaging by the TESS satellite in 2018 and 2020, while Bernardinelli-Bernstein was at 23.8 and 21.3 au, for any notable periodicity. Bernardinelli-Bernstein does not display detectable rotational variability above the noise level in these data.

Keywords: Comets
Algorithmic Speedups and Posterior Biases from Orbit Fitting of Directly Imaged Exoplanets in Cartesian Coordinates. A planet's orbit encodes information about its formation and history. However, exoplanets detected via direct-imaging are often only observed over a small fraction of their periods. Several problems arise from such unconstraining data, like slow convergence of standard orbit-fitting algorithms and significant biases in the estimation of orbital parameters. One possible way of overcoming some of these problems is performing orbit-fits in orbital bases distinct from the usual Keplerian elements. We explore this approach by fitting orbits in Cartesian coordinates, that is, estimating the position and velocity vectors for a planet at a given epoch. We saw a significant improvement in the MCMC convergence time compared to the Keplerian elements, and different posterior shapes were observed with different priors. In particular, setting Gaussian priors in the line-of-sight components (z and $\dot{z}$ ) produced posteriors more similar to the ones obtained via the Keplerian basis compared to uniform priors on them.

Keywords: Bayesian statistics, Exoplanets, Posterior distribution, Exoplanet astronomy, Affine invariant, Direct imaging, Markov chain Monte Carlo, Exoplanet detection methods
Absence of Rapid Line Variations in Consecutive FEROS and NARVAL Spectra of Maia. The comparison of four consecutive high signal-to-noise FEROS spectra of Maia, the fourth brightest member of the Pleiades open cluster, taken over 10 minutes, reveals no real line variations. The analysis of four consecutive I NARVAL profiles of Maia taken over 18 minutes does not show variations either. In particular, the five lines of He I at 4471.48 Å are constant over this timescale in both sets of data. The He I line at 3926.54 Å is very broad and diffuse compared to other photospheric lines of Maia.

Keywords: Chemically peculiar stars
Stellar Multiplicity in an RMHD Simulation with Stellar Feedback. Unlike the Sun, most observed stars are part of a multiple star system, but the formation of such systems is still not well understood. To study this problem, we utilize a run from the STARFORGE simulation suite that simulates the evolution of star-forming Giant Molecular Clouds (GMCs). The run starts with a GMC of an initial mass of 2 × 104 M⊙ and takes gravity, magneto-hydrodynamics and non-isothermal thermodynamics into account. The simulation also includes stellar feedback in the forms of radiation and protostellar jets, where the radiation field is explicitly evolved. In this note, we discuss the orbital period, semimajor axis, multiplicity fraction, and multiplicity frequency distributions, and compare these with observations. We find good agreement with the observed multiplicity fractions but also find a deficit of mass ratios close to unity and close companions, which we attribute to the lack of resolved disks in our simulation.

Keywords: Star formation, Multiple stars, Computational astronomy, Binary stars
Middle Corona Magnetic Field Strength Determined by Spacecraft Radio Faraday Rotation. Faraday rotation (FR) of MESSENGER spacecraft X-band transcoronal radio transmissions were studied to evaluate the mid-coronal magnetic field strength, with the line-of-sight closest solar approach at heliocentric altitudes ranging 1.647-1.817 R⊙. A Community Coordinated Modeling Center (CCMC) CORHEL-MAS 3D coronal field map revealed this region to contain closed magnetic fields. By FR analysis we found a field strength of 118,000 nT at r = 1.647 R⊙, with fall-off to 40,000 nT by r = 1.817 R⊙. These values straddle estimates provided by the CCMC model. The mean value of 79,000 nT at r = 1.732 R⊙ is comparable to the value provided by an established empirical model for average coronal magnetic field strength. FR can be used to evaluate middle coronal magnetic fields, but improved methods to constrain concurrent electron column density will be needed to produce the most accurate results.

Keywords: Solar magnetic fields, Solar corona
Absence of Bursts between 4 and 8 GHz from FRB 20200120E Located in an M81 Globular Cluster. We report the non-detection of dispersed bursts between 4 and 8 GHz from 2.5 hr of observations of FRB 20200120E at 6 GHz using the Robert C. Byrd Green Bank Telescope. Our fluence limits are several times lower than the average burst fluences reported at 600 and 1400 MHz. We conclude that these non-detections are either due to high-frequency bursts being weaker and/or scintillation-induced modulated. It is also likely that our observations were non-concurrent with any activity window of FRB 20200120E.

Keywords: Radio transient sources
Evidence for Multiple Pulse-shape Changes during the Third Chromatic Timing Event of PSR J1713 + 0747. Millisecond pulsar J1713 + 0747 recently underwent a drastic change in its pulse shape. The pulsar has undergone two previous "chromatic timing events," frequency-dependent changes in pulse arrival times, with some evidence for low-amplitude achromatic changes in the pulse shape. Ongoing monitoring efforts of the pulsar show that the latest significant shape change has persisted for several months, longer than the recovery of the behavior in previous events. I examine profiles from the Nançay Radio Telescope presented in Astronomer's Telegram #14642 and find evidence for multiple profile shapes after the start of the third event, hinting at the possibility of several new mode changes to consider.

Keywords: Millisecond pulsars
Six-year Static Sky unWISE Coadds. We present and publicly release a set of deep, full-sky Wide-field Infrared Survey Explorer (WISE) coadds built from WISE and NEOWISE images spanning from early 2010 through late 2018. This data release uniformly incorporates six years of WISE and NEOWISE exposures at 3.4 μm (W1) and 4.6 μm (W2). These inertial "unWISE" stacks allow for detection of roughly a billion stars and galaxies fainter than the AllWISE catalogs sensitivity limit. Importantly, our six-year unWISE coadds, in combination with the crowdsource cataloging software, were used to perform deep source detection/deblending for CatWISE2020.

Keywords: Infrared astronomy, Sky surveys, Astronomy data analysis
Which Milky Way Globular Clusters Might Have Favored an Extraterrestrial Civilization?. Suggestions are offered as to which globular clusters of the Milky Way presented the most favorable conditions for development of an extraterrestrial civilization. Of these NGC 6553 is emphasized.

Keywords: Globular star clusters, Astrobiology
Identification of a White Dwarf Companion in the V* HP Dra System. We present Gaia DR2 2144465183642117888, a previously unknown, wide white dwarf companion to the HP Dra eclipsing binary system. This companion was discovered through the Backyard Worlds: Planet 9 citizen science collaboration. It has separation of 14"4 on the sky from the central eclipsing pair, translating to a projected separation of ~1140 au. We present a review of the orbit and physical parameters of all the components in this now triple system.

Keywords: Eclipsing binary stars, Multiple stars, White dwarf stars
Introducing a Real-time Interactive GUI Tool for Visualization of Galaxy Spectra. To aid the understanding of the nonlinear relationship between galaxy properties and predicted spectral energy distributions (SED), we present a new interactive graphical user interface tool pipes_vis based on BAGPIPES. It allows for real-time manipulation of a model galaxy's star formation history, dust and other relevant properties through sliders and text boxes, with each change's effect on the predicted SED reflected instantaneously. We hope the tool will assist in building intuition about what affects the SED of galaxies, potentially helping to speed up fitting stages such as prior construction, and aid in undergraduate and graduate teaching. pipes_vis is available online (pipes_vis is maintained and documented online at https://github.com/HinLeung622/pipes_vis, or version 0.4.1 is archived in Zenodo (Leung 2021) and also available for installation through pip install pipes_vis).

Keywords: Spectral energy distribution, Galaxy evolution, Astronomy data visualization
Evidence of Early-stage Tidal Structures of Open Clusters Revealed by Kinematics with Gaia EDR3. Blanco 1, a 100 Myr open cluster in the solar neighborhood, is well known for its two 50 pc long tidal tails. Taking Blanco 1 as a reference, we find evidence of early-stage tidal disruption in two other open clusters of ~120 Myr: the Pleiades and NGC 2516, via Gaia EDR3 data. These two clusters have a total mass of 2-6 times that of Blanco 1. Despite having a similar age as Blanco 1, the Pleiades and NGC 2516 have a larger fraction of their members bound: 86% of their mass is inside the tidal radius, versus 63% for Blanco 1. However, a correlation between Blanco 1's 50 pc long tidal tails and the "kinematic tails" in velocity space is also found for the Pleiades and NGC 2516. This evidence supports the idea that the modest elongation seen in the spatial distribution for the Pleiades and NGC 2516 is a result of early-stage tidal disruption.

Keywords: Stellar kinematics, Open star clusters, Tidal distortion