Sazuna/UAT_keywords huggingface dataset:
Gravitational Instability of a Magnetic Rotating Disk with Ohmic Dissipation and Ambipolar Diffusion. We perform a linear analysis of the stability of isothermal, rotating, magnetic, self-gravitating sheets that are weakly ionized. We include a self-consistent treatment of thermal pressure, gravitational, rotational, and magnetic (pressure and tension) forces together with two nonideal magnetohydrodynamic (MHD) effects: Ohmic dissipation and ambipolar diffusion. Our results show that there is always a preferred lengthscale and associated minimum timescale for gravitational instability. The addition of rotation leads to a generalized Toomre criterion (that includes a magnetic dependence) and modified lengthscales and timescales for collapse. We show that both the nonideal MHD effects qualitatively behave in a similar way but have quantitative differences. We apply our results to protostellar disk properties in the early embedded phase and find that the preferred scale of instability can significantly exceed the thermal (Jeans) scale and the peak preferred fragmentation mass is likely to be ∼10-90MJup.

Keywords: Magnetohydrodynamics, Gravitational instability, Star forming regions, Interstellar magnetic fields, Interstellar clouds, Circumstellar disks
First Ultraviolet Outburst Detected from ASASSN-18eh Strengthens Its Interpretation as a Cataclysmic Variable. As part of the Transient UV Objects project, we have discovered a new outburst (at the beginning of 2020 October) of the candidate cataclysmic variable (CV) ASASSN-18eh using the UV/Optical Telescope aboard the Neil Gehrels Swift Observatory. During the outburst its brightness increased by about 6 mag in UV compared to its brightness in the quiescent state. The properties of this outburst are consistent with it being a dwarf nova, strongly supporting the CV nature of ASASSN-18eh.

Keywords: White dwarf stars, Dwarf novae, Ultraviolet photometry, Cataclysmic variable stars, Ultraviolet transient sources
Evidence for Twice-ionized Praseodymium and Neodymium in the Upper Atmosphere of HD 99803 A. Evidence is presented in this Note for the presence of twice ionized praseodymium and neodymium in the upper atmosphere of HD 99803 A, which turns out to be a newly discovered cool HgMn star in a binary system.

Keywords: Chemically peculiar stars, Chemical abundances
Six Years of Luminous X-Ray Emission from the Strongly Interacting Yype-Ib SN2014C Captured by Chandra and NuSTAR. We present the first coordinated soft and hard 0.3-80 keV X-ray campaign of the extragalactic supernova SN2014C in the first ∼2307 days of its evolution. SN2014C initially appeared to be an ordinary type Ib explosion but evolved into a strongly-interacting hydrogen-rich SN IIn over ∼1 yr. We observed signatures of interaction with a dense medium across the X-ray spectrum, which revealed the presence of a ∼1-2M⊙ shell of material at ∼6 × 1016 cm from the progenitor. This finding challenges current understanding of hydrogen-poor core-collapse progenitor evolution. Potential scenarios to interpret these observations include (i) the ejection of the hydrogen envelope by the progenitor star in the centuries prior to the explosion; (ii) interaction of the fast Wolf-Rayet (WR) star wind with the slow, dense wind of the Red Super Giant phase, with an anomalously short WR phase.

Keywords: Supernovae, Stellar mass loss
At Least One in Six Galaxies Is Always Dead. Via numerical experiments, we show that the ∼10%-20% passive fraction seen at z ≳ 3 is consistent with galaxy star formation histories being maximally correlated stochastic processes. If so, this fraction should reflect a time-independent baseline that holds at any epoch or mass regime where mean star formation rates are rising. Data at $\mathrm{log}{M}_{* }\leqslant 10$ and z ≲ 0.5 bear this out, as should future James Webb Space Telescope observations.

Keywords: Galaxy quenching, Star formation, Galaxy evolution
Detection of a Planet in 2M1938+4603 Revisited. The Observed-minus-Calculated diagram shows a stability of a period being analyzed. In case of binary system, any nonlinear O - C variation indicates an orbital period variation that can be caused by e.g., mass loss or mass transfer between components (physical change), additional component(s) to the system (apparent change only). Baran et al. reported a sinusoidal variation of the O - C of 2M 1938+4603 and interpreted it as a circumbinary planet. We analyzed the newest and most reliable release of the Kepler data of 2M 1938+4603 and by using our newest approach we removed two main sources that could cause the variation not to be intrinsic to 2M 1938+4603. We removed significant signal not associated with binarity and folded eclipses to increase their cadences. Consequently, we lowered rms of the O - C diagram by a factor of six confirming the sinusoidal variation reported by Baran et al. and making it even more convincing now.

Keywords: Pulsating variable stars, B subdwarf stars, Space observatories, Exoplanet detection methods, Eclipsing binary minima timing method
Rise of the Phoenix Giants: A Rich History of Dusty Post-merger Stellar Remnants. Hoadley et al. present an exceptional star system hosting orbiting dust and gas and a detached shell of material presumably generated in a stellar merger event. While they claim it to be "the only known merger system not enshrouded by dust," the reality is that this system is a new addition to a remarkable collection of stars first recognized decades ago as likely post-merger stellar remnants. In this note we give an abridged history of evidence for dusty stellar merger remnants in the the Milky Way.

Keywords: Circumstellar matter, Stellar evolution
List of the Close Asteroid Pairs Strongly Perturbed by Three-body Resonances. The two and three body mean motion resonances with Jupiter and Mars (and possible with Earth) may have a significant effect on the dynamics of very young close asteroid pairs and families. The best known example is the influence 9:16 resonance with Mars to some members of Datura family. It is evident, that the evolution of this family can be properly reconstructed only when this fact has been taken into account. One of the results of resonance perturbation may be the temporary compensation of the Yarkovsky drift in the semimajor axis. Studying this relationship may greatly improve the age estimation of asteroid pairs and families. In this note we give a list of some close asteroid pairs in the vicinity of mean motion resonances.

Keywords: Celestial mechanics
K2 Targets Observed in TESS Cycles 1-3. Kepler, K2, and Transiting Exoplanet Survey Satellite (TESS) have demonstrated the power of high-precision uninterrupted photometry. Combining data sets from these two observatories can extend the baseline of high precision photometry on a target. In addition, for some investigations, the differing passbands of the two telescopes may provide additional information about the causes of the observed variability. In order to facilitate studies combining these unique data sets, we present a list of all the 55,641 targets observed by K2 which fell within the TESS field of view during its first three years of observations.

Keywords: Exoplanet astronomy, Stellar astronomy, Catalogs
The Impact of Rotation Velocity on Measuring Magnetic Fields of K and M Stars. Magnetic fields are a critical component of interior and atmospheric models of low-mass stars. Additionally, stellar activity associated with magnetic fields may make exoplanets around K and M stars uninhabitable. Here we describe the measurement of the magnetic fields of K and M dwarfs from high-resolution spectra, and discuss the impact of projected rotational velocity (v sin i) on these measurements. We determine the magnetic fields by measuring the Zeeman effect on Na, Ti, and Ca spectral lines. Observed spectra in our analysis come from the Immersion GRating INfrared Spectrometer (IGRINS), while synthetic spectra were created using the MoogStokes software along with MARCS atmosphere models. We found that measuring Zeeman splitting in R ∼ 45,000 spectra is limited primarily by the projected rotational velocity of the star, but also by spectral resolution, line strength, and spectral signal-to-noise.

Keywords: Infrared astronomy, Low mass stars, Brown dwarfs, Stellar magnetic fields
Appearance of a New Nebula in the Constellation Puppis after an Outburst in 2015 around WISEA J075915.26-310844.6. Here I report the appearance of a new nebula in the constellation Puppis. The nebula was discovered in archived DECam images from 2017 January. Additionally the central source shows an outburst between 2015 February and 2015 April in archived unWISE images. The outburst reached the current brightness in 2016 November (W1 ∼ 3.6 mag, W2 ∼ 1.5 mag). The pre-outburst images from the VST (2012 March) and PanSTARRS (2015 February) do not show any nebulosity around this source. The appearance of reflection nebulae overlapping with the outburst of the central source is known for pre-main sequence stars, such as FU Orionis variables. Follow-up spectroscopy is desired for the central source.

Keywords: FU Orionis stars, Infrared astronomy, Pre-main sequence stars, Star formation, Reflection nebulae
Mid-Infrared Detections of SNe II with NEOWISE. Here I describe 184 mid-infrared detections of supernovae (SNe) in co-added images of the NEOWISE mission. 15 of the SNe had previously unknown long-lasting mid-IR detections with durations of more than a year. I find 7 SNe which have previously unknown SN 2010jl-like mid-infrared evolution. There are also long detections around one type IIb (SN 2016gkg), type IIP (SN 2016X) and type IIL (SN 2016iot). An unusual supernova is SN 2018hna, which shows a drastic color-change in mid-infrared. SN 2018hna begins as a transient with no IR-excess 31 days after the discovery, but changes 158 days later into a transient with strong IR-excess.

Keywords: Type II supernovae, Tidal disruption, Massive stars, Infrared astronomy, Circumstellar matter, Infrared sources
Kalman Filtering for Tip-tilt Correction in Adaptive Optics. Correcting the tip and tilt modes of optical aberrations can mitigate a large proportion of distortions in adaptive optics (AO) systems. We describe a method to greatly improve tip/tilt correction for the Keck telescopes, using a Kalman filter with a physics model conditioned by the expected tip/tilt power spectrum and vibration peaks. The model builds on similar implementations, such as that of the Gemini Planet Imager, by considering the effects of loop delays, the response of the control hardware, and systematics specific to Keck. We demonstrate improved correction in simulation, and discuss how this model could be tuned to a specific telescope and otherwise improved.

Keywords: Astronomical optics
Ephemeris Refinement of the Exoplanet Candidate around the White Dwarf WD1856+534. The exoplanet candidate around the white dwarf WD 1856+534 is of special interest for exoplanet atmosphere characterization because of its very cool temperature and potentially large spectral signal in transmission spectroscopy. Here we present ground-based transit follow-up to verify the transit depth and refine the orbital ephemeris allowing for a more accurate scheduling of future transit observations. Our new ephemeris provides transit time predictions with an uncertainty of less than 30 s until the year 2030.

Keywords: Exoplanet systems
Bright Stars from the Ancient Merger Gaia-Enceladus Visible with Binoculars. We present here a list of 25 bright stars (G &lt; 8) that are possible members of Gaia-Enceladus, a system that merged with the Milky Way approximately 10 Gyr ago, and whose debris dominates the halo near the Sun. These stars were therefore born beyond the edges of the Milky Way and are visible with binoculars. We expect the list to be of interest for public outreach and amateur astronomers. These bright stars are also useful as standard stars for calibration and validation of analysis since very high-quality spectra can be obtained with reasonable amount of telescope time.

Keywords: Amateur astronomy, Stellar kinematics, Chemical abundances, Milky Way stellar halo, Galaxy accretion
GN-z11-flash in the Context of Gamma-Ray Burst Afterglows. The recently discovered rapid transient GN-z11-flash has been suggested to be the prompt-emission ultraviolet (UV) flash associated with a gamma-ray burst (GRB) serendipitously exploding in the ultra-high-z galaxy GN-z11. We here place the flash into the context of the early UV emission of GRBs, and find it is in agreement with the luminosity distribution of these events.

Keywords: Gamma-ray bursts, High-redshift galaxies
Dependence of the Old Star Clusters' Dynamical Clock on the Host Galaxy Gravitational Field. I report outcomes of the analysis of the A+ parameter, which measures the level of radial segregation of blue straggler stars in old star clusters, commonly known as the dynamical clock for the long-term internal dynamical evolution. I used A+ values available in the literature for 48 Milky Way globular clusters. I found that the relationship of A+ and the number of central relaxation times which have elapsed (Nrelax) shows a non negligible dependence on the strength of the host galaxy gravitational potential, in addition to depending on the two-body relaxation mechanism. Indeed, a measured A+ value corresponds to relatively smaller or larger Nrelax values for star clusters located farther or closer to the galaxy center. From an observational point of view, this finding reveals the possibility of disentangling for the first time the dynamical evolutionary stage due to two-body relaxation and tidal effect, that affect the whole star clusters' body concurrently.

Keywords: Globular star clusters, Astronomical methods, Dynamical evolution
Updated Measurements of Proton, Electron, and Oxygen Temperatures in the Fast Solar Wind. The high-speed solar wind is typically the simplest and least stochastic type of large-scale plasma flow in the heliosphere. For much of the solar cycle, it is connected magnetically to large polar coronal holes on the Sun's surface. Because these features are relatively well-known (and less complex than the multiple source-regions of the slow wind), the fast wind is often a useful testing-ground for theoretical models of coronal heating. In order to provide global empirical constraints to these models, here we collect together some older and more recent measurements of the temperatures of protons, electrons, and oxygen ions as a function of radial distance.

Keywords: Solar coronal holes, Solar wind, Solar corona, Space plasmas
A Comparison of Stellar Kinematics Derived from Two Gemini NIFS Reduction Pipelines. The Gemini Near-infrared Integral Field Spectrograph (NIFS) reduction pipeline is widely used to reduce NIFS data. However, there are critical known limitations. A new NIFS reduction pipeline has recently been developed and solves several of these problems. We present a comparison of stellar kinematics derived from the new and old data reduction pipelines, as well as recommendations for optimal NIFS data reduction.

Keywords: Stellar kinematics, Astronomy data reduction, AGN host galaxies
Calibrated Full-frame Images for the TESS Quick Look Pipeline. We describe calibrated TESS images that serve as the input to the MIT Quick Look Pipeline, which we are releasing as a High Level Science Product (HLSP). We also outline the python package tica, which we use to fully calibrate the raw pixels and apply astrometric registration in the form of World Coordinate Solutions. This HLSP could serve as a means for delivering calibrated Full Frame Images to the public promptly after downlink from the spacecraft, which occurs every two weeks. This capability would potentially enable new science investigations with TESS data such as fast follow-up of transient sources and determination of new solar system object ephemerides.

Keywords: Astronomy data analysis, Astronomy data reduction
Differential Chromatic Refraction in the Context of the Legacy Survey of Space and Time. We investigate how measurements of differential chromatic refraction might influence choices for survey strategy in the Legacy Survey of Space and Time.

Keywords: Astronomical methods, Astrometry, Sky surveys, Redshift surveys
OSIRIS-REx Mt. Bigelow Ground Based Bennu Observations Bundle V1.0. This data set includes the ECAS system (Eight Color Asteroid Survey) photometry and light curve observations of the asteroid 101955 Bennu as well as the derived light curves. At the time of the observations, September 2005, the asteroid carried the provisional designation 1999 RQ36. Observations were made as a part of the OSIRIS-REx asteroid sample return mission ground observing campaign to characterize potential mission targets. 101955 Bennu was subsequently chosen as the mission target. This particular data set contains observations of 101955 Bennu and a series of 5 standard stars taken at the University of Arizona Observatories Kuiper 1.54-m reflector.

Keywords: Near-Earth objects, Asteroids
Eight Color Asteroid Survey Bundle V1.0. This data set contains the reflectance spectra and associated data of the Eight Color Asteroid Survey (ECAS), including results for 589 asteroids.

Keywords: Asteroids
Nesvorny HCM Asteroid Families Bundle V1.0. This data set contains asteroid dynamical family memberships for 122 families calculated from synthetic proper elements, including high-inclination families. These families were calculated by David Nesvorny (Nesvorny et al. 2015) using his code based on the Hierarchical Clustering Method (HCM) described in Zappala et al. (1990, 1994). The input synthetic proper elements for 384,337 numbered asteroids were calculated by Knezevic and Milani.

Keywords: Asteroids
A Significant Increase in Detection of High-resolution Emission Spectra Using a Three-dimensional Atmospheric Model of a Hot Jupiter. High-resolution spectroscopy has opened the way for new, detailed study of exoplanet atmospheres. There is evidence that this technique can be sensitive to the complex, three-dimensional (3D) atmospheric structure of these planets. In this work, we perform cross-correlation analysis of high-resolution (R ∼ 100,000) CRIRES/VLT emission spectra of the hot Jupiter HD 209458b. We generate template emission spectra from a 3D atmospheric circulation model of the planet, accounting for temperature structure and atmospheric motions—winds and planetary rotation—missed by spectra calculated from one-dimensional models. In this first-of-its-kind analysis, we find that using template spectra generated from a 3D model produces a more significant detection (6.9σ) of the planet's signal than any of the hundreds of one-dimensional models we tested (maximum of 5.1σ). We recover the planet's thermal emission, its orbital motion, and the presence of CO in its atmosphere at high significance. Additionally, we analyzed the relative influences of 3D temperature and chemical structures in this improved detection, including the contributions from CO and H2O, as well as the role of atmospheric Doppler signatures from winds and rotation. This work shows that the hot Jupiter's 3D atmospheric structure has a first-order influence on its emission spectra at high resolution and motivates the use of multidimensional atmospheric models in high-resolution spectral analysis.

Keywords: High resolution spectroscopy, Hydrodynamical simulations, Hot Jupiters, Radiative transfer simulations, Exoplanet atmospheres
Two Young Planetary Systems around Field Stars with Ages between 20 and 320 Myr from TESS. Planets around young stars trace the early evolution of planetary systems. We report the discovery and validation of two planetary systems with ages ≲300 Myr from observations by the Transiting Exoplanet Survey Satellite (TESS). The $40\mbox{--}320$ Myr old G star TOI-251 hosts a ${2.74}_{-0.18}^{+0.18}\,{R}_{\oplus }$ mini-Neptune with a $4.94$ day period. The $20\mbox{--}160$ Myr old K star TOI-942 hosts a system of inflated Neptune-sized planets, with TOI-942b orbiting in a period of $4.32$ days with a radius of ${4.81}_{-0.20}^{+0.20}\,{R}_{\oplus }$ and TOI-942c orbiting in a period of $10.16$ days with a radius of ${5.79}_{-0.18}^{+0.19}\,{R}_{\oplus }$ . Though we cannot place either host star into a known stellar association or cluster, we can estimate their ages via their photometric and spectroscopic properties. Both stars exhibit significant photometric variability due to spot modulation, with measured rotation periods of ∼3.5 days. These stars also exhibit significant chromospheric activity, with age estimates from the chromospheric calcium emission lines and X-ray fluxes matching that estimated from gyrochronology. Both stars also exhibit significant lithium absorption, similar in equivalent width to well-characterized young cluster members. TESS has the potential to deliver a population of young planet-bearing field stars, contributing significantly to tracing the properties of planets as a function of their age.

Keywords: Exoplanet evolution, Exoplanets
Center for Astrophysics Optical Infrared Science Archive. I. FAST Spectrograph. We announce the public release of 141,531 moderate-dispersion optical spectra of 72,247 objects acquired over the past 25 yr with the FAST Spectrograph on the Fred L. Whipple Observatory 1.5 m Tillinghast telescope. We describe the data acquisition and processing so that scientists can understand the spectra. We highlight some of the largest FAst Spectrograph for the Tillinghast Telescope (FAST) survey programs, and make recommendations for use. The spectra have been placed in a Virtual Observatory-accessible archive and ready for download.

Keywords: Astronomy databases, Optical astronomy, Astronomy data analysis, Galaxy radial velocities, Spectroscopy, Radial velocity, Astronomy data reduction
On the Compatibility of Ground-based and Space-based Data: WASP-96 b, an Example. The study of exoplanetary atmospheres relies on detecting minute changes in the transit depth at different wavelengths. To date, a number of ground- and space-based instruments have been used to obtain transmission spectra of exoplanets in different spectral bands. One common practice is to combine observations from different instruments in order to achieve a broader wavelength coverage. We present here two inconsistent observations of WASP-96 b, one by the Hubble Space Telescope (HST) and the other by the Very Large Telescope (VLT). We present two key findings in our investigation: (1) a strong water signature is detected via the HST WFC3 observations and (2) a notable offset in transit depth (&gt;1100 ppm) can be seen when the ground-based and space-based observations are combined. The discrepancy raises the question of whether observations from different instruments could indeed be combined. We attempt to align the observations by including an additional parameter in our retrieval studies but are unable to definitively ascertain that the aligned observations are indeed compatible. The case of WASP-96 b signals that compatibility of instruments should not be assumed. While wavelength overlaps between instruments can help, it should be noted that combining data sets remains risky business. The difficulty of combining observations also strengthens the need for next-generation instruments that possess broader spectral coverage. * These authors contributed equally to this work.

Keywords: Observational astronomy, Exoplanet atmospheric composition , Bayesian statistics, Exoplanet atmospheres