Sazuna/UAT_keywords huggingface dataset:
A Photometric and Spectroscopic Study of the Short-period Algol EW Boötis with a δ Sct Pulsator. In this paper, we present Transiting Exoplanet Survey Satellite (TESS) photometry and high-resolution spectra of the short-period Algol EW Boo. We obtained double-lined radial velocities (RVs) from the time-series spectra and measured the effective temperature of the primary star as T eff,1 = 8560 ± 118 K. For the orbital period study, we collected all times of minima available for over the last 30 yr. It was found that the eclipse timing variation of the system could be represented by a periodic oscillation of 17.6 ± 0.3 yr with a semiamplitude of 0.0041 ± 0.0001 day. The orbital and physical parameters were derived by simultaneously analyzing the TESS light and RV curves using the Wilson-Devinney (WD) binary star modeling code. The component masses and radii were showed over 3% precision: M 1 = 2.67 ± 0.08 M ⊙, M 2 = 0.43 ± 0.01 M ⊙, R 1 = 2.01 ± 0.02 R ⊙, and R 2 = 1.35 ± 0.01 R ⊙. Furthermore, multiple frequency analyses were performed for the light-curve residuals from the WD model. As a result, we detected 17 pressure-mode pulsations in the region of 40.15-52.37 day-1. The absolute dimensions and pulsation characteristics showed that the δ Sct pulsator was the more massive and hotter primary star of the EW Boo.

Keywords: Eclipsing binary stars, Algol variable stars, Pulsating variable stars
Adaptive Optics Imaging Can Break the Central Caustic Cusp Approach Degeneracy in High-magnification Microlensing Events. We report new results for the gravitational microlensing target OGLE-2011-BLG-0950 from adaptive optics images using the Keck Observatory. The original analysis by Choi et al. and reanalysis by Suzuki et al. report degenerate solutions between planetary and stellar binary lens systems. This particular case is the most important type of degeneracy for exoplanet demographics because the distinction between a planetary mass or stellar binary companion has direct consequences for microlensing exoplanet statistics. The 8 and 10 yr baselines allow us to directly measure a relative proper motion of 4.20 ± 0.21 mas yr-1, confirming the detection of the lens star system and ruling out the planetary companion models that predict a ~4× smaller relative proper motion. The Keck data also rule out the wide stellar binary solution unless one of the components is a stellar remnant. The combination of the lens brightness and close stellar binary light-curve parameters yields primary and secondary star masses of ${M}_{{\rm{A}}}={1.12}_{-0.09}^{+0.11}$ and ${M}_{{\rm{B}}}={0.47}_{-0.10}^{+0.13}\,{M}_{\odot }$ at a distance of ${D}_{L}={6.70}_{-0.30}^{+0.55}\,$ kpc and a projected separation of ${0.39}_{-0.04}^{+0.05}\,$ au. Assuming that the predicted proper motions are measurably different, the high-resolution imaging method described here can be used to disentangle this degeneracy for events observed by the Roman exoplanet microlensing survey using Roman images taken near the beginning or end of the survey.

Keywords: Binary stars, High-resolution microlensing event imaging, Galactic bulge, Binary lens microlensing, Gravitational microlensing
Asteroseismology of a Double-mode High-amplitude δ Scuti Star TIC 448892817. We propose that TIC 448892817 is a double-mode high-amplitude δ Scuti star. The radial modes detected in this star provide a unique opportunity to exploit asteroseismic techniques up to their limits. 30 significant frequencies are detected by frequency analysis, while two of them are independent frequencies, i.e., F0 = 13.43538(2) day-1 and F1 = 17.27007(4) day-1. The ratio of f 1/f 2 is measured to be 0.777957(2), suggesting that this target is a double-mode δ Scuti star. Nearly all the light variation is due to these two modes and their combination frequencies, but several other frequencies of very low amplitude are also present. The stellar evolutionary models were constructed with different mass M and metallicity Z using Modules for Experiments in Stellar Astrophysics (MESA). The frequency ratio f 1/f 2 obtained by the model is smaller than those obtained by observation. This might be caused by the rotation of the star pointing that rotational effects are more important than previously thought in HADS stars. This is something that deserves to be investigated in future works with models including rotational effects for moderate to intermediate rotators such as FILOU. On the other hand, the parameters obtained from MESA agree well with previous results as well as by observational spectra. The best-fitting model shows that TIC 448892817 is close to entering the first turnoff of the main sequence. In order to accurately determine the effective temperature and metallicities, thus further narrowing the parameter space of this star, we suggest high-resolution spectra is highly desired in the future.

Keywords: Stellar oscillations, Asteroseismology, Delta Scuti variable stars
High-resolution Linear Spectropolarimetry of Red Supergiant VY CMa: Identification of Atomic and Molecular Features. We present a high-resolution optical spectropolarimetric observation of the red supergiant VY CMa. The optical spectrum of VY CMa contains numerous emission features that are mainly due to molecular bands of TiO, ScO, and VO. In addition, emission lines of Ba II, Ca I, Na I, K I, and Rb I are identified in the spectrum. Our observation shows that all the molecular bands exhibit a very large and abrupt linear polarization reduction, i.e., depolarization, across the band heads of up to 10% or higher with respect to the continuum polarization level. The high-resolution observations demonstrate clearly that the molecular band heads are associated with the largest depolarization. Using this property together with a simulated emission spectrum of TiO we are able to identify most of the broad emission features in the optical spectrum of VY CMa as the TiO band heads in emission. Our observations also reveal a previously unknown phenomenon that the atomic lines either in emission or absoprtion also exhibit large depolarization across the line profile, with the K I doublet showing almost complete depolarization. The observed polarization pattern is very similar among either absoprtion or emission lines, even though the spectral lines belong to different atomic species. Together with recent high spectral resolution observations, we discuss the origin of this phenomenon and suggest that the observed large depolarization across molecular bands and atomic lines is due to absorption and scattering in the complex circumstellar environment of VY CMa, especially in the dense dusty clumps located almost on the plane of the sky.

Keywords: Starlight polarization, A supergiant stars
Evidence of Long-term Period Variations in the Exoplanet Transit Database (ETD). We analyze a large number of citizen science data and identify eight hot Jupiter systems that show evidence for deviations from a constant orbital period: HAT-P-19 b, HAT-P-32 b, TrES-1 b, TrES-2 b, TrES-5 b, WASP-4 b, WASP-10 b, and WASP-12 b. The latter system is already well known to exhibit strong evidence for tidal orbital decay and serves as an important control for this study. Several other systems we identify have disputed period drifts in the literature, allowing the results here to serve as an independent analysis. The citizen science data are from the Exoplanet Transit Database (ETD), which is a global project established in 2008 by the Variable Star and Exoplanet Section of the Czech Astronomical Society. With over 400 planets and 12,000 contributed observations spanning 15 yr, the ETD is brimming with potential for studying the long-term orbital evolution of close-in hot Jupiters. We use our results to discuss prioritization of targets for follow-up investigations, which will be necessary to confirm the period drifts and their causes.

Keywords: Exoplanet dynamics, Transit timing variation method, Exoplanets
Search for an Alien Message to a Nearby Star. If alien probes have colonized the whole galaxy, they could have formed an efficient galactic-scale communication network by establishing direct gravitationally lensed links between neighboring systems. Under this scenario, observing the positions opposite the nearest ecliptic stars represents a promising artifact SETI strategy that could make it possible to "eavesdrop" on the emission of local probes to one of these stars. In this context, we present here a first attempt to detect optical messages emitted from the solar system to the ecliptic star Wolf 359, the third-nearest stellar system, based on observations gathered by the TRAPPIST-South and SPECULOOS-South robotic telescopes. While sensitive enough to detect constant emission with emitting power as small as a few watts, this search led to a null result. We note that the putative alien probes could be emitting "off-axis" and be located much closer to the Sun than the start of the "solar gravitational line" at 550 au. We performed a search for such an off-axis emitter in our data, whose result turned out negative too.

Keywords: Search for extraterrestrial intelligence, Technosignatures, Astrobiology
The Space Density of Intermediate-redshift, Extremely Compact, Massive Starburst Galaxies. We present a measurement of the intrinsic space density of intermediate-redshift (z ~ 0.5), massive (M * ~ 1011 M ⊙), compact (R  e  ~ 100 pc) starburst (ΣSFR ~ 1000 M ⊙ yr-1 kpc-1) galaxies with tidal features indicative of them having undergone recent major mergers. A subset of them host kiloparsec-scale, &gt; 1000 km s-1 outflows and have little indication of AGN activity, suggesting that extreme star formation can be a primary driver of large-scale feedback. The aim for this paper is to calculate their space density so we can place them in a better cosmological context. We do this by empirically modeling the stellar populations of massive, compact starburst galaxies. We determine the average timescale on which galaxies that have recently undergone an extreme nuclear starburst would be targeted and included in our spectroscopically selected sample. We find that massive, compact starburst galaxies targeted by our criteria would be selectable for $\sim {148}_{-24}^{+27}$ Myr and have an intrinsic space density ${n}_{\mathrm{CS}}\sim ({1.1}_{-0.3}^{+0.5})\times {10}^{-6}\,{\mathrm{Mpc}}^{-3}$ . This space density is broadly consistent with our z ~ 0.5 compact starbursts being the most extremely compact and star-forming low-redshift analogs of the compact star-forming galaxies in the early universe, as well as them being the progenitors to a fraction of intermediate-redshift, post-starburst, and compact quiescent galaxies.

Keywords: Starburst galaxies, Galaxy evolution, Post-starburst galaxies, Compact galaxies
Blackbody Temperature of 200+ Stellar Flares Observed with the CoRoT Satellite. We estimated blackbody temperature for 209 flares observed at 69 F-K stars, significantly increasing the number of flare temperature determinations. We used the Blue and Red channels obtained by the 27 cm telescope of the CoRoT satellite at high cadence and long duration. The wavelength limits of the channels were estimated using spectra from the Pickles library for the spectral type and luminosity class of each star, provided by the Exodat Database. The temperatures were obtained from the flare energy Blue-to-Red ratio, using the flare equivalent duration and stellar flux in both channels. The expected value of the analyzed flares is equal to 6400 K with a standard deviation of 2800 K, where the mean stellar spectral type, weighted by the number of flares in each spectral subclass, is equal to G6. Contrary to our results, a stellar white-light flare is often assumed to emit as a blackbody with a temperature of 9000 or 10,000 K. Our estimates agree, however, with values obtained for solar flares. The GAIA G-band transmissivity is comparable to that of the CoRoT White channel, which allows us to calibrate the flares to the Gaia photometric system. The energy in the G band of the analyzed flares varies between 1032 and 1037 erg, and the flare area ranges from 30 μsh to 3 sh (solar hemisphere). The energy release per area in a flare is proportional to ${T}_{\mathrm{flare}}^{2.6}$ , at least up to 10,000 K.

Keywords: Stellar properties, Astrostatistics, Artificial satellites, Stellar flares, Optical flares, Stellar rotation
An Analysis of the Eclipsing Binaries HD 71636, V1022 Cassiopeiae, and OT Andromedae. We have obtained high-dispersion spectroscopy and BV photometry of two F-type eclipsing binaries, HD 71636 and V1022 Cas, plus the A-type system OT And. Transiting Exoplanet Survey Satellite measurements for each system have also been incorporated. The photometry of HD 71636 enables a more consistent picture of this 5.01331 days, circular-orbit system to emerge. The F2 V primary has a mass of 1.506 ± 0.002 M ⊙ and a radius of 1.583 ± 0.024 R ⊙. The mass of the F5 V secondary is 1.282 ± 0.002 M ⊙, and its radius is 1.314 ± 0.030 R ⊙. Comparison with evolutionary models of the Modules for Experiments in Stellar Astrophysics (MESA) series results in a good fit for a composition of [Fe/H] = 0.12 and an age of 0.9 Gyr. For the F6 V stars of V1022 Cas, our analysis produces a period of 12.15616 days and an eccentricity of 0.312. The two components have nearly equal masses of 1.626 ± 0.001 M ⊙ and 1.607 ± 0.001 M ⊙. The radii of the primary and secondary are 2.570 ± 0.021 R ⊙ and 2.445 ± 0.022 R ⊙, respectively. Comparison with the MESA evolutionary models results in [Fe/H] = 0.08 and an age of 1.87 Gyr. OT And consists of a pair of similar mid-A stars that have an orbital period of 20.85292 days and an eccentricity of 0.215. The primary has a mass of 2.253 ± 0.014 M ⊙ and a radius of 3.167 ± 0.013 R ⊙. The corresponding parameters for the secondary are 2.147 ± 0.011 M ⊙ and 2.649 ± 0.015 R ⊙, respectively. The MESA series models produce a best fit for this system with [Fe/H] = 0.10 and an age of 0.675 Gyr. The total apsidal motion in both eccentric systems is less than 1.°5 century-1.

Keywords: Spectroscopic binary stars, Eclipsing binary stars, Fundamental parameters of stars, Detached binary stars
A Transmission Spectrum of the Sub-Earth Planet L98-59 b in 1.1-1.7 μm. With the increasing number of planets discovered by the Transit Exoplanet Survey Satellite, the atmospheric characterization of small exoplanets is accelerating. L98-59 is an M-dwarf hosting a multiplanet system, and so far, four small planets have been confirmed. The innermost planet b is ~15% smaller and ~60% lighter than Earth, and should thus have a predominantly rocky composition. The Hubble Space Telescope observed five primary transits of L98-59 b in 1.1-1.7 μm, and here we report the data analysis and the resulting transmission spectrum of the planet. We measure the transit depths for each of the five transits and, by combination, we obtain a transmission spectrum with an overall precision of ~20 ppm in for each of the 18 spectrophotometric channels. With this level of precision, the transmission spectrum does not show significant modulation, and is thus consistent with a planet without any atmosphere or a planet having an atmosphere and high-altitude clouds or haze. The scenarios involving an aerosol-free, H2-dominated atmosphere with H2O or CH4 are inconsistent with the data. The transmission spectrum also disfavors, but does not rule out, an H2O-dominated atmosphere without clouds. A spectral retrieval process suggests that an H2-dominated atmosphere with HCN and clouds or haze may be the preferred solution, but this indication is nonconclusive. Future James Webb Space Telescope observations may find out the nature of the planet among the remaining viable scenarios.

Keywords: Extrasolar rocky planets, Exoplanet atmospheric composition , Astronomy data analysis, Transmission spectroscopy, Exoplanet atmospheres
The Emptiness Inside: Finding Gaps, Valleys, and Lacunae with Geometric Data Analysis. Discoveries of gaps in data have been important in astrophysics. For example, there are kinematic gaps opened by resonances in dynamical systems, or exoplanets of a certain radius that are empirically rare. A gap in a data set is a kind of anomaly, but in an unusual sense: instead of being a single outlier data point, situated far from other data points, it is a region of the space, or a set of points, that is anomalous compared to its surroundings. Gaps are both interesting and hard to find and characterize, especially when they have nontrivial shapes. We present in this paper a statistic that can be used to estimate the (local) "gappiness" of a point in the data space. It uses the gradient and Hessian of the density estimate (and thus requires a twice-differentiable density estimator). This statistic can be computed at (almost) any point in the space and does not rely on optimization; it allows us to highlight underdense regions of any dimensionality and shape in a general and efficient way. We illustrate our method on the velocity distribution of nearby stars in the Milky Way disk plane, which exhibits gaps that could originate from different processes. Identifying and characterizing those gaps could help determine their origins. We provide in an appendix implementation notes and additional considerations for finding underdensities in data, using critical points and the properties of the Hessian of the density. 7 7 A Python implementation of t methods presented here is available at https://github.com/contardog/FindTheGap.

Keywords: Astrostatistics techniques, Computational astronomy, Milky Way dynamics, Astronomy data analysis
Investigating 2M1155-79B: A Nearby, Young, Low-mass Star Actively Accreting from a Nearly Edge-on, Dusty Disk. We investigate the nature of an unusually faint member of the ϵ Cha association (D ~ 100 pc, age ~5 Myr), the nearest region of star formation of age &lt;8 Myr. This object, 2MASS J11550336-7919147 (2M1155-79B), is a wide-separation (~580 au), comoving companion to low-mass (M3) ϵ Cha association member 2MASS J11550485-7919108 (2M1155-79A). We present near-infrared (NIR) spectra of both components, along with analysis of photometry from Gaia Early Data Release 3, the Two Micron All Sky Survey, the Vista Hemisphere Survey, and the Wide-field Infrared Survey Explorer (WISE). The NIR spectrum of 2M1155-79B displays strong He I 1.083 emission, a sign of active accretion and/or accretion-driven winds from a circumstellar disk. Analysis of WISE archival data reveals that the mid-infrared excess previously associated with 2M1155-79A instead originates from the disk surrounding 2M1155-79B. Based on these results, as well as radiative transfer modeling of its optical/IR spectral energy distribution, we conclude that 2M1155-79B is most likely a young, late M star that is partially obscured by, and actively accreting from, a nearly edge-on circumstellar disk. This would place 2M1155-79B among the rare group of nearby (D ≲ 100 pc), young (age &lt;10 Myr) mid-M stars that are orbited by and accreting from highly inclined protoplanetary disks. Like these systems, the 2M1155-79B system is a particularly promising subject for studies of star and planet formation around low-mass stars.

Keywords: Pre-main sequence stars, Protoplanetary disks
Visual Orbits of Spectroscopic Binaries with the CHARA Array. IV. HD 61859, HD 89822, HD 109510, and HD 191692. We present the visual orbits of four spectroscopic binary stars, HD 61859, HD 89822, HD 109510, and HD 191692, using long baseline interferometry with the CHARA Array. We also obtained new radial velocities from echelle spectra using the APO 3.5 m, CTIO 1.5 m, and Fairborn Observatory 2.0 m telescopes. By combining the astrometric and spectroscopic observations, we solve for the full, three-dimensional orbits and determine the stellar masses to 1%-12% uncertainty and distances to 0.4%-6% uncertainty. We then estimate the effective temperature and radius of each component star through Doppler tomography and spectral energy distribution analyses. We found masses of 1.4-3.5 M ⊙, radii of 1.5-4.7 R ⊙, and temperatures of 6400-10,300 K. We then compare the observed stellar parameters to the predictions of the stellar evolution models, but found that only one of our systems fits well with the evolutionary models.

Keywords: Binary stars, Fundamental parameters of stars, Spectroscopic binary stars, Long baseline interferometry, Visual binary stars
Magnetic Interactions in Orbital Dynamics. The magnetic field of a host star can impact the orbit of a stellar partner, planet, or asteroid if the orbiting body is itself magnetic or electrically conducting. Here, we focus on the instantaneous magnetic forces on an orbiting body in the limit where the dipole approximation describes its magnetic properties as well as those of its stellar host. A permanent magnet in orbit about a star will be inexorably drawn toward the stellar host if the magnetic force is comparable to gravity due to the steep radial dependence of the dipole-dipole interaction. While magnetic fields in observed systems are much too weak to drive a merger event, we confirm that they may be high enough in some close compact binaries to cause measurable orbital precession. When the orbiting body is a conductor, the stellar field induces a time-varying magnetic dipole moment that leads to the possibility of eccentricity pumping and resonance trapping. The challenge is that the orbiter must be close to the stellar host, so that magnetic interactions must compete with tidal forces and the effects of intense stellar radiation.

Keywords: Exoplanet dynamics, Star-planet interactions, Magnetic stars, Stellar magnetic fields
The Arizona Radio Observatory 1 mm Spectral Survey of the Hypergiant Star NML Cygni (215-285 GHz). A sensitive (1σ rms ≤ 3 mK; 2 MHz resolution) 1 mm spectral survey (214.5-285.5 GHz) of the envelope of the oxygen-rich supergiant star NML Cygni (NML Cyg) has been conducted using the 10 m Submillimeter Telescope of the Arizona Radio Observatory. These data represent the first spectral line survey of NML Cyg and are complementary to a previous 1 mm survey of the envelope of a similar hypergiant, VY Canis Majoris (VY CMa). The complete NML Cyg data set is presented here. In the survey, 104 emission lines were observed, arising from 17 different molecules and 4 unidentified features. Many of the observed features have complex line profiles, arising from asymmetric outflows characteristic of hypergiant stars. While most of the lines in the survey arise from SiO, SO, SO2, and SiS, CO had the strongest emission. Five other C-bearing species are identified in the survey (HCN, CN, HCO+, CS, and HNC), demonstrating an active carbon chemistry despite the O-rich environment. Moreover, NS was observed, but not NO, although favorable transitions of both molecules lie in the surveyed region. Sulfur chemistry appears to be prominent in NML Cyg and plays an important role in the collimated outflows. The refractory species observed, NaCl and AlO, have narrow emission lines, indicating that these molecules do not reach the terminal expansion velocity. NaCl and AlO likely condense into dust grains at r &lt; 50 R *. From NaCl, the chlorine isotope ratio was determined to be 35Cl/37Cl = 3.85 ± 0.30.

Keywords: Circumstellar envelopes, Isotopic abundances, Millimeter astronomy, Molecular spectroscopy, Astrochemistry, Stellar mass loss, Stellar winds, Hypergiant stars, Stellar evolution