Sazuna/UAT_keywords huggingface dataset:
Blue Coma and Red Surface of 174P/Echeclus: Two Sides of the Same Coin?. Seccull et al. (2019) report a dramatic difference in the color of the coma and surface of Centaur 174P/Echeclus. While the coma was blue in appearance, the surface was red. A similar phenomenon was found in laboratory optical measurements of single-scattering feldspar particles and of a surface comprised of these same particles. Thus, the observations do not necessarily suggest different chemical composition and size distribution of dust in the coma and surface of 174P/Echeclus. Instead, the observed difference could arise from multiple-scattering phenomena that makes a significant contribution to light scattering by a regolith, but does not appear in an optically thin coma.

Keywords: Multi-color photometry, Centaur group, Comae, Comet surfaces, Coma dust
Recurring Outbursts of P/2019 LM<SUB>4</SUB> (Palomar). We present a preliminary analysis of comet P/2019 LM4 (Palomar) as observed by the Zwicky Transient Facility (ZTF) survey in 2019 and 2020. We find that the discovery of the comet in 2019 and the recovery in 2020 is largely attributed to two separate outbursts that are ≳2 and ≳3.9 mag in strength. The two outbursts occurred between the end of April and early May in 2019, and between 2020 May 8.31 and 9.52 UTC.

Keywords: Comets, Short period comets
Population Analysis of Supernova Remnants in the Galaxy Using Evolutionary Models. One aim of supernova remnant (SNR) evolution models is to deduce fundamental properties of a supernova (SN) explosion from the current state of its SNR. The SNR hot plasma is characterized by its observed X-ray spectrum: electron temperature, emission measure and abundances. This plasma is heated by the SNR forward shock and reverse shocks. The state of the plasma is also predicted by SNR models. We have developed spherically symmetric models (Leahy &amp; Williams 2017; Leahy et al. 2019) and have applied these to observations, e.g., for LMC SNRs (Leahy 2017) and for inner Galaxy SNRs (Leahy &amp; Ranasinghe 2018). The models allow inference of SNR explosion energy, circumstellar medium density, age, ejecta mass and ejecta density profile. We obtain new results by including Galactic SNRs that have adequate observations.

Keywords: Supernova remnants
Maunder's Work on Planetary Habitability in 1913: Early Use of the term "Habitable Zone" and a "Drake Equation" Calculation. E. W. Maunder's popular book "Are the Planets Inhabited?" has a strikingly modern perspective on the question, and may be the first use in this context of the phrase "habitable zone."

Keywords: Habitable zone
Hα Luminosity of ATLAS18qtd Does Not Plateau in the Nebular Phase. We present new spectroscopic and photometric observations of ATLAS18qtd/SN 2018cqj, a fast-declining SN Ia with variable Hα emission in previously published nebular phase spectra. ATLAS18qtd is undetected in both spectroscopic and photometric observations which occurred at ∼540 days after maximum light and ∼230 days after the last Hα detection. With these new non-detections, we place an upper limit on the Hα luminosity of $\lesssim 1.1\times {10}^{36}\,\mathrm{erg}\,{{\rm{s}}}^{-1}$ indicating the Hα flux decreased by a factor of $\gtrsim 4$ since the previous detection. This upper limit excludes Hα emission that plateaus or increases since the previous detection but cannot confirm that the Hα emission decay rate is equivalent to the supernova decay rate.

Keywords: Circumstellar matter, Type Ia supernovae
Deconfusing the Confusogram: Getting New Insights from Zeeman Doppler Imaging. Zeeman Doppler Imaging (ZDI) is a powerful tool for characterizing the strength and topology of stellar magnetic fields. In this research note, we present a new way to visualize the typical results from ZDI for an ensemble of stars, addressing some of the concerns with the standard "confusogram" approach to illustrating the data. Our publicly available plotting methods further enable an accessible means to consider variability in the inferred magnetic field topologies from repeated observations, as we demonstrate with the literature ZDI data on M dwarfs.

Keywords: M dwarf stars, Stellar magnetic fields
Transit Analysis of Exoplanets TrES-5 b and WASP-43 b with the EXOplanet Transit Interpretation Code. In this study, we analyze light curves and corresponding transit attributes of the exoplanets TrES-5b and WASP-43b. The mid-transit time of an exoplanet is the time in which the planet is in the middle of its transit. Over time, due to variations that arise after many periods, the error in the mid-transit time of the exoplanet increases. Because of this, constant observations of exoplanet mid-transit times through light curves are necessary to update the transit timing predictions. We made light curves with the EXOplanet Transit Interpretation Code (EXOTIC). To run with EXOTIC, we were given raw, uncalibrated TrES-5b images taken by the SRO telescope, managed by the Boyce-Astro project. Additionally, we requested and obtained images of WASP-43b using the Las Cumbres Observatory 0.4 m robotic telescopes. Within this work, we will explore the newly calculated mid-transit times and other transit properties to gain a better understanding of TrES-5b and WASP-43b.

Keywords: Exoplanet astronomy, Exoplanet detection methods, Exoplanet systems, Exoplanets
Comparing Approximate Bayesian Computation with the Poisson-Likelihood Method for Exoplanet Occurrence Rates. We present Kepler exoplanet occurrence rates inferred with approximate Bayesian computation (ABC). By using the same planet catalog, stellar sample, and characterization of completeness and reliability as Bryson et al. (2020), we are able to provide the first direct comparison of results from ABC to those derived with the popular Poisson-likelihood method. For planets with orbital periods between 50 and 400 days and radii between 0.75 and 2.5 R⊕, we find an integrated occurrence rate ${F}_{0}={0.596}_{-0.099}^{+0.092}$ planets per GK dwarf star. After correcting for reliability against astrophysical false positives and false alarms, we find ${F}_{0}={0.421}_{-0.072}^{+0.086}$ . Our findings agree within 1σ of Bryson et al. (2020), indicating that the results are robust and not method-dependent.

Keywords: Exoplanet catalogs, Bayesian statistics, Astrostatistics, Exoplanet astronomy, Exoplanet detection methods, Transit photometry, Astrostatistics strategies
A Variable X-Ray Source Close to the Magnetar SGR 1935+2154. The recent discovery of a millisecond radio burst from the Galactic magnetar SGR 1935+2154 has initiated an intense discussion about the connection between magnetars and fast radio bursts (FRBs). Although some properties of the radio burst from SGR 1935+2154are not the same as cosmological FRBs, there are theoretical models which propose a connection between magnetars and FRBs (see review by Margalit et al. 2020). In particular, the role of a magnetar wind nebula is included in some models, and therefore it is worthwhile to investigate the X-ray environment of SGR 1935+2154 in more detail. Here, we report on the discovery of an X-ray transient feature near SGR 1935+2154 using archival Chandra data and discuss its possible origin.

Keywords: Neutron stars, Magnetars, X-ray transient sources, Radio bursts
A Pair of Tidally Disrupted Galaxies from The Hubble Legacy Archive. We describe archival, serendipitously obtained Hubble Space Telescope (HST) observations of a tidally disturbed galaxy pair (AM 0436-472 NED01/LEDA 503707) located at z = 0.058 (240 Mpc). The system likely belongs to peculiar ring galaxies of Solitaire type. We also analyze an archival optical spectrum of AM 0436-472 NED01 and report an upper limit in X-rays (0.2-10 keV).

Keywords: Galaxy interactions, Galaxies
Non-detection of M60-UCD1 in Quasi-simultaneous X-Ray and Radio Observations. Simultaneous detection in X-rays and radio, following the proportionality implied by the "fundamental plane of black hole activity," can indicate the presence of an accreting black hole (BH), allowing a rough estimate of its mass. We used the XMM-Newton satellite and the Karl G. Jansky Very Large Array to perform quasi-simultaneous observations (within 24 hr) of the ultra-compact dwarf galaxy M60-UCD1, where the presence of a supermassive BH was inferred from stellar dynamics. The galaxy was not detected in either the X-ray or the radio band. We used the fundamental plane of BH activity to set constraints on the mass of any BH that might reside in its nucleus.

Keywords: Ultracompact dwarf galaxies, Galaxies, Astrophysical black holes
The Distance to B335. Reflection nebulosity surrounds HD 184982. The medium responsible is apparently related to the nearby Bok globule B335. Thus the star and the globule must lie at similar distances, which according to the Gaia DR2 parallax of HD 184982 is 164.5 pc.

Keywords: Dark interstellar clouds, Protostars, Bok globules
Nanoflare Theory and Stochastic Reconnection. Local magnetic reversals are an inseparable part of magnetohydrodynamic turbulence whose collective outcome may lead to a global reconnection with a rate independent of the small scale physics—stochastic reconnection. We show that this picture is related to the nanoflare theory, which is one of the most plausible models to solve the coronal heating problem. The magnetic field follows the turbulent flow in a statistical sense by means of stochastic flux freezing. Hence the turbulence, which bends and stretches the initially smooth field, will tend to increase the field's spatial complexity. Strong magnetic shears associated with such a highly tangled field can trigger local reversals and field annihilations on a wide range of inertial scales, which convert magnetic energy into kinetic and thermal energy respectively. The former enhances the turbulence while the latter enhances heat generation on any inertial scale. These theoretical predictions are supported by scaling laws and simulations.

Keywords: Solar coronal heating, Solar corona, Solar magnetic reconnection
Fast Generation of Large-scale Structure Density Maps via Generative Adversarial Networks. Generative Adversarial Networks (GANs) are a recent advancement in unsupervised machine learning. They are a cat-and-mouse game between two neural networks: (1) a discriminator network which learns to validate whether a sample is real or fake compared to a training set and (2) a generator network which learns to generate data that appear to belong to the training set. Both networks learn from each other until training is complete and the generator network is able to produce samples that are indistinguishable from the training set. We find that GANs are well-suited for fast generation of novel 3D density maps that are indistinguishable from those obtained from N-body simulations. In a matter of seconds, a fully trained GAN can generate thousands of density maps at different epochs in the history of the universe. These GAN-generated maps can then be used to study the evolution of large-scale structure over time.

Keywords: Neural networks, Large-scale structure of the universe, Convolutional neural networks, Voids, Cosmic web
The Curious Case of the Chromospherically (and Isochronally) Candescent K Stars. A significant fraction of apparently isochronally young, chromospherically active (UV-luminous) K and early-M stars appear to have anomalous kinematics and display weak X-ray emission. We demonstrate that the combination of UV excesses, X-ray fluxes, and newly available rotation rates from the TESS mission can potentially serve to assess the youth (or lack thereof) of these candidate pre-main sequence field stars. This approach holds promise for purposes of distinguishing between "bona fide" young, low-mass stars and "imposters"—overluminous, UV-bright ZAMS or evolved main sequence stars—and could shed light on why the latter might masquerade as the former.

Keywords: Stellar evolution
The Low-mass Members of the Ursa Major Association. We present a set of over-densities in spatial-kinematic space previously identified by Kounkel &amp; Covey (2019) that may constitute extended tidal tails associated with the nearby, 400 Myr old Ursa Major association. This sample of 1599 stars has a main-sequence turnoff point consistent with the age of Ursa Major, and might contain its missing low-mass members. It includes four candidate white dwarfs with properties that seem consistent with a total age of about 400 Myr, but we estimate from older white dwarf interlopers that about 33% of the sample may be contaminated by random field stars.

Keywords: Stellar kinematics, Astronomy data analysis, Proper motions
Halo Environment for Population III Star Formation. We analyze the environmental features and growth history of high-redshift halos from cosmological simulation data to determine the conditions that lead to Population III star formation. We use support-vector classification (SVC) to determine the separation in feature-space between Population III halos and halos that form no stars. We perform hyperparameter tuning but are unable to produce an SVC model that reliably classifies Population III halos. We perform feature selection and determine that among our included features, Lyman-Werner radiation and halo mass have the most significant impact on an SVC model's effectiveness.

Keywords: Galaxy formation, Population III stars
VLA/Realfast Detection of a Burst from FRB 180916.J0158+65 and Tests for Periodic Activity. We report on the detection of a burst from FRB 180916 by realfast/Very Large Array and present software for interpreting fast radio bursts (FRB) periodicity. We demonstrate a range of periodicity analyses with bursts from FRB 180916, FRB 121102 and FRB 180814. Our results for FRB 180916 and FRB 121102 are consistent with published results. For FRB 180814, we did not detect any significant periodic episodes. The realfast-detected and other high-frequency bursts for FRB 180916 tend to lie at the beginning of the activity window, indicating a possible phase-frequency relation. The python package frbpa can be used to reproduce and expand on this analysis to test models for repeating FRBs.

Keywords: Radio bursts, High energy astrophysics, Radio transient sources
Spectral Variability of a Soft-intermediate State QPO from MAXI J1820+070. Black Hole X-ray binaries are known to exhibit variability in their light curves on timescales as short as milliseconds and as long as months. The short-timescale variability can be in the form of quasi-periodic oscillations (QPOs), which may be produced by general relativistic effects. In this work, we looked at low-frequency QPOs from an exciting recent black hole transient, MAXI J1820+070, which first went into outburst in 2018. This source was observed in a multi-wavelength campaign that included the NICER mission, a soft X-ray telescope attached to the International Space Station. In our analysis, we applied X-ray timing and spectral-timing techniques to help place constraints on the QPO emission mechanism in the extreme environment surrounding the black hole. Although the QPO amplitude was too low to carry out phase-resolved spectroscopy, our work indicates that weak QPOs such as this one may be present in the light curves of many sources.

Keywords: Low-mass x-ray binary stars, High time resolution astrophysics, Black holes
Stratospheric Transparency and Color of the Total Lunar Eclipse of 1794 February 14 Observed by Jovellanos from Gijón (Spain). Gaspar Melchor de Jovellanos is the major figure of the Age of Enlightenment in Spain. He observed the total lunar eclipse of 1794 February 14 from Gijón (north of Spain). Jovellanos described the moon color as "glowing iron." It indicates that the stratosphere around 1794 seems to have been undisturbed volcanically as previous estimates indicate.

Keywords: Lunar eclipses, Atmospheric effects, History of astronomy
Breakthrough Listen Search for Technosignatures toward the Kepler-160 System. We have conducted a search for artificial radio emission associated with the Kepler-160 system following the report of the discovery of the Earth-like planet candidate KOI-456.04 on 2020 June 4 (Heller et al. 2020). Our search targeted both narrowband (2.97 Hz) drifting (±4 Hz s-1) and wideband pulsed (5 ms at all bandwidths) artificially dispersed technosignatures using the turboSETI (Enriquez et al. 2017) and SPANDAK (V. Gajjar et al. 2020, in preparation) pipelines, respectively, from 1 to 8 GHz. No candidates were identified above an upper limit Equivalent Isotropic Radiated Power of 5.9 × 1014 W for narrowband emission and 7.3 × 1012 W for wideband emission. Here we briefly describe our observations and data reduction procedure.

Keywords: Search for extraterrestrial intelligence, Technosignatures
Origin of Sources of Repeating Fast Radio Bursts with Periodicity in Close Binary Systems. It is proposed that sources of repeating fast radio bursts with detected periodicity are magnetars with extremely short initial spin periods at the protoneutron star stage, formed in binaries after tidal synchronization of their progenitor cores during late stages of thermonuclear burning in very close systems with orbital periods about a few days. This formation channel is in several respects different from evolution of progenitors of normal magnetars, and thus, it explains some differences between repeating and non-repeating sources of fast radio bursts.

Keywords: Neutron stars, Magnetars, Compact objects
A Search for Bursts from FRB 191228 in Breakthrough Listen Archival Data. We describe archival Breakthrough Listen (BL) observations of Fomalhaut which is within the 90% confidence localization region of FRB 191228. We report non-detection of any radio bursts in a total of 6.4 hr of BL data.

Keywords: Radio bursts, Transient sources, Radio transient sources
Dynamical Masses of Young Stars Inferred from Two Transitions of CO with ALMA. Stellar masses are fundamental but often difficult to measure. Thanks to the Atacama Large Millimeter Array (ALMA) and Gaia, dynamical masses of pre-main sequence stars can be precisely measured using the Keplerian rotation of protoplanetary disks. We used ALMA CO(2-1) and CO(3-2) observations of CT Cha and DS Tau to determine their masses by modeling the geometry, kinematics, and physical properties of their disks with a Bayesian-based radiative transfer modeling code (pdspy). We found that the posterior distributions of the masses from the two transitions are inconsistent at the 2-4σ level. These systematic errors may originate from assumptions in the disk model, or perhaps the modest spatial or spectral resolutions used in this study. Regardless, this indicates that dynamical mass measurements using disk kinematics should be treated with caution when using only a single transition line because of these systematic errors.

Keywords: Radio interferometry, Protoplanetary disks, CO line emission
Recovery of Returning Halley-type Comet 12P/Pons-Brooks with the Lowell Discovery Telescope. We report the recovery of returning Halley-type comet 12P/Pons-Brooks using the 4.3 m Lowell Discovery Telescope, at a heliocentric distance of 11.89 au. Comparative analysis with a dust model suggests that the comet may have been active since ∼30 au from the Sun. We derive a nuclear radius of 17 ± 6 km from the nucleus photometry, though this number is likely an overestimate due to the contamination from dust and gas. Continuing monitoring is encouraged in anticipation of the comet's forthcoming perihelion in 2024 April.

Keywords: Comets, Short period comets
Radio Propagation Studies of the Solar Wind in the Era of Parker Solar Probe. The NASA Parker Solar Probe mission is providing unprecedented measurements of solar wind plasma and plasma turbulence at heliocentric distances as small as 0.125 au, or 26.9 solar radii. Radioastronomical remote sensing measurements of the coronal and solar wind plasma have been made since the 1960s over a heliocentric distance range that overlaps with and extends that of Parker Solar Probe. This paper will compare radio scintillation and Parker Solar Probe results on the heliocentric-distance-dependence of the plasma density variance (where there may be an inconsistency between the two techniques), the speed at which turbulence density irregularities move radially with respect to the Sun, and other topics.

Keywords: Space plasmas, Solar wind, Solar corona
DDO Photometry for Some Late-type Stars. Extensive DDO photometric data are provided for selected subgiants and chromospherically active RS CVn binaries. A search for an improved DDO temperature-corrected luminosity calibration for late type stars is described.

Keywords: Late-type stars
The Evolutionary Status of 17 Com, The Hottest Member of Coma Berenices. The integrated flux, linear radius and effective temperature of 17 Com A (A0p CrEu), the hottest member of the Coma Berenices open cluster, are determined using the Infrared Flux Method. The surface gravity is derived by fitting the Hβ profile. The effective temperature and surface gravity are found to be smaller than most previous determinations. The evolutionary status of 17 Com A is discussed in light of these new parameters using stellar evolution modeling. 17 Com A appears to be finishing its lifetime on the Main Sequence.

Keywords: Open star clusters, Ap stars, Stellar evolution
Modeling of Galactic Foreground Polarization with Velocity Gradients. The detection of primordial B-mode polarization is still challenging due to the relatively low amplitude compared to the galactic foregrounds. To remove the contribution from the foreground, a comprehensive picture of the galactic magnetic field is indispensable. The Velocity Gradient Technique (VGT) is promising in tracing magnetic fields based on the modern understanding of the magneto-hydrodynamic turbulence. In this work, we apply VGT to an H I region containing an intermediate velocity cloud and a local velocity cloud, which are distinguishable in position-position-velocity space. We show that VGT gives an excellent agreement with the Planck polarization and stellar polarization. We confirm the advantages of VGT in constructing the 3D galactic magnetic field.

Keywords: Interstellar magnetic fields, Interstellar dynamics, Interstellar medium
Elemental Abundance Consequence of Adding Two Bulk Earths to the Solar Convection Zone. We calculate the abundance change if two bulk earths were added to the solar convection zone, which is assumed to be 5 × 1031 gm or 0.025 M⊙. The resulting differential abundance plot resembles those found in stellar precision differential abundance studies.

Keywords: Chemical abundances, G stars
Locating Red Supergiants in the Galaxy IC10. We use archival near-IR photometry to identify red supergiants (RSGs) in the starburst galaxy IC10. RSGs are the coolest of the evolved massive stars and have K and M spectral types and temperatures below 4100 K. Typically, they can be up to a thousand times the radius of the Sun, and are therefore highly luminous. Using archival 2MASS and UKIRT photometry we transformed J and K colors to effective temperatures and luminosities, which allowed us to identify the RSGs. After applying temperature and luminosity constraints and eliminating foreground stars using Gaia, we arrived at our finalized list of 138 RSGs. Of this list, 26 were confirmed RSGs based on Gaia parallaxes, with the remaining 112 being unconfirmed proposed IC10 RSGs.

Keywords: Starburst galaxies, Red supergiant stars, Active galaxies, Supergiant stars, Late-type supergiant stars
An Apparent Jump in the Radio Position of J1147+3501. The fundamental celestial reference frame is realized by observations of extragalactic radio sources using the technique of very long baseline interferometry (VLBI). Compact radio-emitting active galactic nuclei are regularly used as reference points for relative positioning of other radio sources. VLBI absolute astrometric data indicate that the nucleus of the nearby radio galaxy J1147+3501 apparently changed its position by about 0"02 some time between 1999 and 2017. We suggest that this unusually large displacement is a consequence of a drastic change in the source brightness distribution as revealed by archival high-resolution VLBI images.

Keywords: Active galaxies