Sazuna/UAT_keywords huggingface dataset:
Original Research by Young Twinkle Students (Orbyts): Ephemeris Refinement of Transiting Exoplanets II. We report follow-up observations of four transiting exoplanets, TRES-2 b, HAT-P-22 b, HAT-P-36 b and XO-2 b, as part of the Original Research By Young Twinkle Students (ORBYTS) program. These observations were taken using the Las Cumbres Observatory Global Telescope Network's (LCOGT) robotic 0.4 m telescopes and were analyzed using the HOlomon Photometric Software (HOPS). Such observations are key for ensuring accurate transit times for upcoming telescopes, such as the James Webb Space Telescope, Twinkle (Edwards et al. 2019b) and Ariel (Tinetti et al. 2018), which may seek to characterize the atmospheres of these planets. The data have been uploaded to ExoClock and a significant portion of this work has been completed by secondary school students in London.

Keywords: Transit photometry, Amateur astronomers, Exoplanets
The Far-ultraviolet Variations of 17 Com. All the archival International Ultraviolet Explorer spectra of 17 Com, the most massive member of the open cluster Coma Berenices, are used to show that the far-ultraviolet spectral energy distribution shows large variations at wavelengths shorter than 1800 Å. The large far-ultraviolet variations are most likely due to spots or belts of overabundant elements (chromium in particular) which come and go into the line of sight as the star rotates.

Keywords: Chemically peculiar stars
The Most Interesting Anomalies Discovered in ZTF DR3 from the SNAD-III Workshop. The search for objects with unusual astronomical properties, or anomalies, is one of the most anticipated results to be delivered by the next generation of large scale astronomical surveys. Moreover, given the volume and complexity of current data sets, machine learning algorithms will undoubtedly play an important role in this endeavor. The SNAD team is specialized in the development, adaptation and improvement of such techniques with the goal of constructing optimal anomaly detection strategies for astronomy. We present here the preliminary results from the third annual SNAD workshop (https://snad.space/2020/) that was held on-line in 2020 July.

Keywords: AGN host galaxies, Outlier detection, Transient detection, Supernovae
Newly Discovered Papers of S. Chandrasekhar and an Ethical Dilemma. Subrahmanyan Chandrasekhar (1910-1995) was one of the most important figures of 20th-Century astrophysics. The closing of Yerkes Observatory by the University of Chicago in 2018 led to discovery in Chandrasekhar's old Yerkes office of several boxes of items he had left. They included a sealed envelope, which when opened revealed an inner sealed envelope on which was written "Please do not examine contents. Thanks. S. Chandrasekhar." This paper discusses how the authors handled the ethical dilemma of balancing the wishes of a deceased scientific icon versus the obvious possibility that the envelope contained materials of historical importance.

Keywords: History of astronomy
The Explosion and Progenitor Properties of Type IIP Supernovae Inferred from MESA and STELLA Modeling. The progenitors of Type IIP supernovae (SNe) are known to be red supergiants, but their properties are not well determined. We employ hydrodynamical modeling to investigate the explosion characteristics of eight Type IIP SNe and the properties of their progenitor stars. We create evolutionary models using the MESA stellar evolution code, explode these models, and simulate the optical light curves using the STELLA code. We fit the optical light curves, Fe II 5169 Å velocity, and photospheric velocity to the observational data. Our fits give a progenitor ZAMS mass of &lt;19 M☉ for seven of the SNe. Where previous progenitor mass estimates exist from various sources, such as hydrodynamical modeling, multiwavelength observations, or semianalytic calculations, our modeling generally tends toward the lower-mass values. We are unable to fit one event, SN 2015ba well, but our best fit indicates a progenitor mass closer to 24 M☉.

Keywords: Astronomy data modeling, Red supergiant stars, Core-collapse supernovae, Type II supernovae, Light curves, Stellar evolutionary models
Would SN1993J Have Been Detected by Next-generation Cerenkov Instruments?. Already in the first days after the explosion of a supernova, the strong shock expanding forward into the dense wind of the progenitor star can theoretically accelerate particles up to the ∼PeV (=1015 eV) range. These accelerated particles, interacting with the dense wind material, should lead to the production of gamma-rays in the 1-100 TeV range, through pion production. However, no supernova has yet been detected by current Cerenkov instruments, and the question of the detectability of extragalactic supernovae in nearby galaxies (within a few Mpc) by next generation instruments is still open. The detection in the TeV range is especially hindered by the two-photon annihilation process, in which high-energy gamma-rays interact with soft photons from the photosphere to produce electron/positron pairs, thereby degrading the gamma-ray signal from the system. We calculate the temporal evolution of the expected gamma-ray attenuation in the well-studied type IIb SN 1993J, accounting for both temporal and geometrical effects.

Keywords: Gamma-ray astronomy, Type II supernovae
A Recipe for Transforming ICRS Coordinates to a Cartesian Coordinate System Centered on a Cluster. For the purpose of studying internal kinematics of a star cluster it is often convenient to convert the astrometric parameters of its members into cluster-centered Cartesian coordinates. I provide a detailed and rigorous derivation of such a coordinate transformation and briefly compare it with a selection of published procedures from literature.

Keywords: Astronomical location
Historical Perspectives on the Concept of Galaxy Size. A brief narrative on how the effective radius and isophotal diameters were accepted as galaxy size measures is presented. Evidence suggests that these parameters were defined only based on observational premises, independent of any astrophysical theories. An alternative, new physically motivated size definition based on the expected gas density threshold required for star formation in galaxies is proposed. The intrinsic scatter of the size-stellar mass relation using the new size measure is 0.06 dex, three times smaller than that of the relation with the effective radius as size. The new physically motivated size measure can be adopted in upcoming deep, wide imaging surveys.

Keywords: Galaxy formation, Galaxy evolution, Galaxy properties, History of astronomy
Teaching with Code: Globular Cluster Distance Lab. Modern astronomy increasingly depends on computational thinking. Although some astronomy courses for undergraduates use computing, high school astronomy courses often have little computing. Created as a part of a research experience for teachers in astronomy and another in computer science, this project leverages robotic telescope images and astronomical algorithms to determine the distance to a star cluster using variable stellar photometry. Students investigate Python and Jupyter Notebook to analyze astronomical images to calculate the interstellar distance to a star cluster across the Milky Way. Students will learn how to write Python code that runs in a Jupyter Notebook such that the brightness of stars in an astronomical image can be determined. The real astronomical image data will be directly manipulated and analyzed by code the students create. Student project files and teacher solution files are provided. Code is open source, and materials are available for classroom use.

Keywords: Computational astronomy, Educational software, Astronomy software, Astronomy data analysis, Photometry, Photographic photometry
When "Boring" Stars Flare: The Ultraviolet Activity of GJ 887, a Bright M Star Hosting Newly Discovered Planets. GJ 887 has been spotlighted for the apparently gentle space environment it provides to its recently discovered planets. In 27 days of optical monitoring by the Transiting Exoplanet Survey Satellite (TESS), the star exhibited no detectable flares. Ultraviolet observations reveal a different story. Two high-contrast flares occurred in just 2.8 hr of far-ultraviolet monitoring by the Hubble Space Telescope. Solar scalings indicate these flares were X-class or larger events, generally associated with coronal mass ejections on the Sun. Hundreds of events of equal or greater energy likely occurred during the TESS monitoring, but produced optical contrasts too small to be detected. Strong yet optically undetectable ultraviolet flares like these could dominate the high energy emission of all M stars throughout their lives, impacting the photochemistry and erosion of atmospheres on orbiting planets. * Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.

Keywords: Ultraviolet astronomy, Stellar flares, Exoplanets, M stars
Are Centaurs Comet Nuclei?. Centaurs are an interesting class of small bodies orbiting between Jupiter and Neptune. Several show some sort of activity and are classified as comets, in addition to minor planets. However, is activity a sufficient criterion for comet classification? The ancient definition of a comet as a small body orbiting the Sun that shows activity needs to be revisited in light of detailed knowledge gathered by spacecraft missions and modern telescopes. A new definition should take into account physico-chemical properties, dynamics, time and place of origin, activity mechanisms, and other important aspects. In this paper, the ability of Centaurs to bind an atmospheres is discussed from a cometary perspective. Large Centaurs may represent transition objects between comets with extensive exospheres and bodies with thin, tightly bound atmospheres, typical of some planets and large satellites. In this regard, large Centaurs are more like comets, sharing the characteristic of unbound gaseous atmospheres.

Keywords: Comet nuclei, Comets, Centaur group
Rotational Variability in the TESS Light Curve of 21 Com. We present an analysis of the TESS-based light curve of the chemically peculiar A-type (Ap) star 21 Com (HD 108945). We used the simple aperture photometry light curve with a time span of 27 days. A least-squares fit to the data with 10 harmonics yields a frequency of 0.48726 day-1, which corresponds to a rotational period of 2.05229 days. Furthermore, we find no evidence of any short-term variability beyond the pure rotational signature.

Keywords: Stellar rotation, Chemically peculiar stars
Lopsided Satellite Distributions around Isolated Host Galaxies. We summarize preliminary results from a new analysis of the spatial distributions of the satellites of isolated host galaxies. We identify 789 host-satellite systems in the NASA-Sloan Atlas, each with 5 or more satellites. Consistent with previous studies, we find that, on average, the satellites of red hosts are located preferentially close to their hosts' major axes, while the satellites of blue hosts are distributed isotropically. The pairwise clustering of the satellites reveals a strong tendency for pairs of satellites to be located on the same side of their host, resulting in lopsided satellite distributions. The signal is most pronounced for the satellites of blue hosts, where we find ∼50% more satellite pairs on the same side of their host than on opposite sides. For red hosts, we find ∼6% more satellite pairs on the same side of their host than on opposite sides.

Keywords: Galaxies
Near the Edge of the Atira Orbital Realm: Short-term Dynamical Evolution of 2020 HA<SUB>10</SUB> and 2020 OV<SUB>1</SUB>. Atiras or Interior Earth Objects (IEOs) have their orbits contained entirely within the orbit of Earth. The first IEO, 1998 DK36, was found in 1998; out of the 23 known Atiras, 15 have been discovered during the last decade. Here, we provide a preliminary assessment of the current dynamical status and short-term orbital evolution of 2020 HA10 and 2020 OV1, two recently discovered Atiras. Our calculations indicate that 2020 HA10 periodically switches between the Aten and Atira orbital realms, and although it is almost certainly a present-day Atira, it spends most of the time following Aten-type orbits. In contrast, 2020 OV1 is well entrenched within the Atira orbital realm, but it might have arrived there relatively recently.

Keywords: Solar system, Asteroids
Extended Point-spread Functions for Deep Astronomical Imaging Surveys. The low surface brightness (LSB) universe is one of the last frontiers in observational astronomy. However, uncovering the information contained in ultra-deep imaging is technically challenging. In this contribution, we present one of the fundamental tools of LSB astronomers: correcting for the extended Point-Spread Function (PSF), which is critical to characterize the LSB properties of astronomical images. We show how to build the extended PSF (approximately 5' in radius), in 5 bands (grizY), of one of the most important modern deep surveys: the Hyper-Suprime Camera (HSC) one on the 8.2 m Subaru telescope. These PSFs have been obtained by sampling individual point-like sources at different brightness. The techniques used here can be applied to the next generation of deep astronomical imaging surveys as the LSST.

Keywords: Surveys, Galaxy formation, Galaxy evolution, Catalogs
Red Satellite Galaxies: The Best Tracers of Host-mass Distribution in the Illustris-TNG100 Simulation. We use the IllustrisTNG100-1 simulation to investigate the degree to which satellite galaxies trace the mass density of large, isolated host galaxies. As expected, the mass density profiles of the host galaxies are well fitted by Navarro, Frenk &amp; White profiles. The degree to which the satellite number density profiles trace the hosts' mass density profiles is a strong function of host and satellite color. For red hosts, the number density profile of blue satellites is significantly less than the host mass density profile for all host-satellite separations r ≲ 0.8r200. For blue hosts, the number density profile of blue satellites agrees fairly well with the host mass density profile for all host-satellite separations r ≲ 0.8r200. For both red and blue hosts, we find that red satellites are the best tracers of the mass density profiles within the hosts' virial radii.

Keywords: Galaxy dark matter halos, Dwarf galaxies, Dark matter, Galaxies
Elemental Abundances in Supernova Remnant W49B as Clues to Its Progenitor. We apply the Smoothed Particle Inference (SPI) technique to analyze the X-ray emission from SNR W49B. In X-rays, it is visible as a centrally filled supernova remnant, and was recently recognized as one of the first remnants to have plasma that is overionized. Using SPI we infer the density structure and derive the mass of individual elements in the plasma over the entire remnant. We have compared the abundances inferred with SPI to those obtained from a wide range of supernova explosion models, including both Type Ia and core-collapse, as well as energetic and off-center variants. Type Ia models that incorporate some form of detonation are found to be the most compatible, while pure deflagration models, and all core-collapse models, are found to be incompatible.

Keywords: Supernova remnants, Isotopic abundances, Interstellar medium, X-ray sources
White Dwarfs in Close Binaries: A Systematic Search for Mass-transfer Systems and Supernova Ia Progenitors in the APOGEE Survey. We have created a new and unique database, the APOGEE-Galaxy Evolution Explorer (GALEX)-Gaia catalog, to study white dwarfs in close binaries, and, in particular, to: (1) create a minimally biased sample of white dwarf-main sequence (WDMS) systems derived from the combination of GALEX, Gaia, and the dual hemisphere, multi-epoch, high-resolution, infrared APOGEE-1 and -2 spectroscopic surveys, and (2) exploit this catalog to vastly increase the number of well-characterized WDMS systems having derived dynamical parameters (e.g., masses, separation, orbital periods, etc.) as well as precision multi-element chemical compositions by exploiting the high resolution, multi-epoch data from APOGEE. This catalog will significantly further our understanding of compact binary evolution.

Keywords: Surveys, White dwarf stars, Compact binary stars, Common envelope evolution
The Mass Function of Supermassive Black Holes in the Direct Collapse Scenario. One of the ideas to explain the existence of supermassive black holes (SMBH) in place by z ∼ 7 is a phase of rapid accretion onto direct collapse black holes (DCBH) that started their lives with masses ∼104-5 ${M}_{\odot }$ . Considering the DCBH scenario, we show that the SMBH mass function has two characteristic features: 1. a power-law at intermediate masses whose index is the dimensionless ratio α ≡ λ/γ, where λ is the growth rate of the number of DCBH and γ is the growth rate of DCBH masses, both during the DCBH growth era; 2. a break in the power law profile set by β ≡ γ T, where T is the duration of the DCBH growth era. The observed quasar luminosity function can be described with this tapered power-law function.

Keywords: Supermassive black holes, Quasars
Techniques for Constraining the Abundance of Nonplanetary Substellar Objects. An interesting problem of relativistic astrophysics is the possible existence of non planetary Compact SubStellar Objects (CSSOs), such as black holes, but also non-standard objects such as boson stars. The challenge is to detect and distinguish them from ordinary planets. Here we present a new approach to this problem, which consists in detecting directly these CSSOs using exoplanet searches by transits, radial velocity measurements and astrometry and comparing the results to standard planet models.

Keywords: Black holes
The Importance of Having an Extended Point-spread Function in Low Surface-brightness Science. Obtaining and characterizing the extended point-spread function (PSF) is essential to extract accurate photometric information from deep imaging surveys. In this contribution, we present the extended PSFs of the Sloan Digital Sky Survey (SDSS). By stacking images of individual stars with different brightness, two-dimensional SDSS PSFs extending over 8 arcmin in radius for all the SDSS filters have been obtained. We demonstrate how to use the PSF models for correcting the scattered light field produced by the brightest stars in the Coma cluster central region field. This example shows the enormous importance of extended PSFs in the study of the low-surface brightness Universe, especially with the upcoming of ultra-deep surveys such as the Large Synoptic Survey Telescope (LSST). All PSF models and the scripts used to obtain them are publicly available and further details can be found in Infante-Sainz et al. (2020).

Keywords: Surveys, Catalogs, Astronomy data analysis, Galaxy stellar halos, Photometry, Astronomical methods, Galaxies, Low surface brightness galaxies
The Break-by-one Gamma Distribution: A Proper and Tractable Alternative to the Schechter Function for Modeling Cosmic Populations. The break-by-one gamma distribution has a probability density function resembling the Schechter function, but with the small-argument behavior modified so it is normalizable in commonly arising cases where the Schechter function is not. Its connection to the gamma distribution makes it straightforward to sample from. These properties make it useful for cosmic demographics.

Keywords: Luminosity function, Astrostatistics distributions, Stellar mass functions, Star counts, Galaxy luminosities
Compositing Eclipse Images from the Ground and from Space. We present composite white-light images of the 2019 July 2, total solar eclipse, from the minimum of the solar-activity cycle. We exhibit high-resolution high dynamic range composites from three observation sites in Chile, including one made of 646 individual ground-based images and with such a wide field it exceeds the field of view of the Naval Research Laboratory's C2 and C3 coronagraphs aboard ESA's Solar and Heliospheric Observatory. We compare the resolution of the coronal streamers and other magnetic phenomena of the corona. We also show continuity of features on the solar surface as observed from NOAA's GOES-16 and GOES-17 Solar Ultraviolet Imager.

Keywords: Solar coronal streamers, Solar coronal plumes, Solar K corona, Quiet solar corona
The Visualization and Measurements of Mass Functions with LEGO. We promote the concept of mass functions for interdisciplinary science education and communication. A mass function characterizes the frequency distribution of the masses of objects in the universe. We present an experiment to demonstrate this concept to a diverse audience of science students, using popular LEGO toys. We discovered that the LEGO mass function is surprisingly similar compared to mass functions of astronomical objects such as stars and galaxies.

Keywords: Initial mass function, Pareto distribution, Stellar mass functions, Mass ratio, Interdisciplinary astronomy, Astronomy data visualization
The Large Flux Variations of 17 Com A as Recorded by FUSE. Inspection of archival FUSE spectra of the Ap star 17 Com A (HD 108662) reveals large flux variations from 905 to 1187 Å over the 5.0808 days rotational period. These variations are of larger amplitude than those observed in the ultraviolet range with IUE from 1200 to 2000 Å. At 1161 Å, where the flux reaches a maximum, the variation of flux with rotational phase shows a double-wave structure similar to that of the Transiting Exoplanet Survey Satellite lightcurve. These large flux variations are most likely caused by the passage of spots or belts of overabundant elements in the line of sight as the star rotates The FUSE spectrum of 17 Com A contains mostly blends of low-excitation lines of Mn II, Cr II and Fe II and interesting lines of C I, C III, P II, S II and Cl I.

Keywords: Chemically peculiar stars
Optimizing Numerical Simulations of Colliding Galaxies. I. Fitness Functions and Optimization Algorithms. Gravitational n-body models can be used to simulate the dynamical evolution of colliding galaxies. Given observational data in the form of images of the galaxies, we seek to estimate the true values of various dynamical parameters through the careful application of optimization methods. However, optimizing these models can be quite difficult due to (1) their expensive run-time, (2) the dimensionality and complexity of the parameter space which must be explored, (3) the presence of morphological symmetries which introduce many false extrema into the fitness landscape, and (4) the fact that the majority of orbital trajectories produce systems with little to no tidal features. To combat these issues, we have developed novel "two-factor" fitness functions for image similarity quantification and an adaptive genetic algorithm with crossover and mutation operators designed to handle parameter correlation. We test these methods by fitting to a synthetic target image.

Keywords: Computational astronomy, Computational methods