Sazuna/UAT_keywords huggingface dataset:
Identifying Periodic Variable Stars and Eclipsing Binary Systems with Long-term Las Cumbres Observatory Photometric Monitoring of ZTF J0139+5245. We present the results of our search for variable stars using the long-term Las Cumbres Observatory (LCO) monitoring of white dwarf ZTF J0139+5245 with the two 1.0 m telescope nodes located at McDonald Observatory using the Sinistro imaging instrument. In this search, we find 38 variable sources, of which 27 are newly discovered or newly classified (71%) based on comparisons with previously published catalogs, thereby increasing the number of detections in the field of view under consideration by a factor of ≈2.5. We find that the improved photometric precision per exposure due to longer exposure time for LCO images combined with the greater time sampling of LCO photometry enables us to increase the total number of detections in this field of view. Each LCO image covers a field of view of 26' × 26' and observes a region close to the Galactic plane (b = -9°4) abundant in stars with an average stellar density of ≈8 arcmin-2. We perform aperture photometry and Fourier analysis on over 2000 stars across 1560 LCO images spanning 537 days to find 28 candidate BY Draconis variables, three candidate eclipsing binaries of type EA, and seven candidate eclipsing binaries of type EW. In assigning preliminary classifications to our detections, we demonstrate the applicability of the Gaia color-magnitude diagram as a powerful classification tool for variable-star studies.

Keywords: Periodic variable stars, Surveys, Time domain astronomy, Eclipsing binary stars, BY Draconis stars
Analysis of Polarimetry Data with Angular Uncertainties. For a track based polarimeter, such as the Imaging X-ray Polarimetry Explorer (IXPE), the sensitivity to polarization depends on the modulation factor, which is a strong function of energy. In previous work, a likelihood method was developed that would account for this variation in order to estimate the minimum detectable polarization (MDP). That method essentially required that the position angles of individual events should be known precisely. In a separate work, however, it was shown that using a machine-learning method for measuring event tracks can generate track angle uncertainties, which can be used in the analysis. Here, the maximum likelihood method is used as a basis for revising the estimate of the MDP in a general way that can include uncertainties in event track position angles. The resultant MDP depends solely upon the distribution of track angle uncertainties present in the input data. Due to the physics of the IXPE detectors, it is possible to derive a simple relationship between these angular uncertainties and the energy-dependent modulation function as a step in the process.

Keywords: X-ray astronomy, Astronomical techniques, Polarimetry
TOI-532b: The Habitable-zone Planet Finder confirms a Large Super Neptune in the Neptune Desert orbiting a metal-rich M-dwarf host. We confirm the planetary nature of TOI-532b, using a combination of precise near-infrared radial velocities with the Habitable-zone Planet Finder, Transiting Exoplanet Survey Satellite (TESS) light curves, ground-based photometric follow up, and high-contrast imaging. TOI-532 is a faint (J ~ 11.5) metal-rich M dwarf with Teff = 3957 ± 69 K and [Fe/H] = 0.38 ± 0.04; it hosts a transiting gaseous planet with a period of ~2.3 days. Joint fitting of the radial velocities with the TESS and ground-based transits reveal a planet with radius of 5.82 ± 0.19 R⊕, and a mass of ${61.5}_{-9.3}^{+9.7}$ M⊕. TOI-532b is the largest and most massive super Neptune detected around an M dwarf with both mass and radius measurements, and it bridges the gap between the Neptune-sized planets and the heavier Jovian planets known to orbit M dwarfs. It also follows the previously noted trend between gas giants and host-star metallicity for M-dwarf planets. In addition, it is situated at the edge of the Neptune desert in the Radius-Insolation plane, helping place constraints on the mechanisms responsible for sculpting this region of planetary parameter space.

Keywords: Hot Neptunes, Radial velocity, Transit photometry, Extrasolar gaseous planets
K2, Spitzer, and TESS Transits of Four Sub-Neptune Exoplanets. We present new Spitzer transit observations of four K2 transiting sub-Neptunes: K2-36 c, K2-79b, K2-167b, and K2-212b. We derive updated orbital ephemerides and radii for these planets based on a joint analysis of the Spitzer, TESS, and K2 photometry. We use the EVEREST pipeline to provide improved K2 photometry, by detrending instrumental noise and K2's pointing jitter. We used a pixel-level decorrelation method on the Spitzer observations to reduce instrumental systematic effects. We modeled the effect of possible blended eclipsing binaries, seeking to validate these planets via the achromaticity of the transits (K2 versus Spitzer). However, we find that Spitzer's signal-to-noise ratio for these small planets is insufficient to validate them via achromaticity. Nevertheless, by jointly fitting radii between K2 and Spitzer observations, we were able to independently confirm the K2 radius measurements. Due to the long time baseline between the K2 and Spitzer observations, we were also able to increase the precision of the orbital periods compared to K2 observations alone. The improvement is a factor of 3 for K2-36 c, and more than an order of magnitude for the remaining planets. Considering possible JWST observations in 1/2023, previous 1σ uncertainties in transit times for these planets range from 74-434 minutes, but we have reduced them to the range of 8-23 minutes.

Keywords: Exoplanet astronomy, Photometry
The Youngest Planet to Have a Spin-Orbit Alignment Measurement AU Mic b. We report measurements of the sky-projected spin-orbit angle for AU Mic b, a Neptune-size planet orbiting a very young (~20 Myr) nearby pre-main-sequence M-dwarf star, which also hosts a bright, edge-on, debris disk. The planet was recently discovered from preliminary analysis of radial-velocity observations and confirmed to be transiting its host star from photometric data from the NASA's TESS mission. We obtained radial-velocity measurements of AU Mic over the course of two partially observable transits and one full transit of planet b from high-resolution spectroscopic observations made with the MINERVA-Australis telescope array. Only a marginal detection of the Rossiter-McLaughlin effect signal was obtained from the radial velocities, in part due to AU Mic being an extremely active star and the lack of full transit coverage plus sufficient out-of-transit baseline. As such, a precise determination of the obliquity for AU Mic b is not possible in this study and we find a sky-projected spin-orbit angle of $\lambda ={47}_{-54}^{{+26}^{\circ}} $ . This result is consistent with both the planet's orbit being aligned or highly misaligned with the spin axis of its host star. Our measurement independently agrees with, but is far less precise than observations carried out on other instruments around the same time that measure a low-obliquity orbit for the planet. AU Mic is the youngest exoplanetary system for which the projected spin-orbit angle has been measured, making it a key data point in the study of the formation and migration of exoplanets-particularly given that the system is also host to a bright debris disk.

Keywords: Exoplanets, Hot Neptunes, Radial velocity, Exoplanet astronomy, Exoplanet detection methods, Dynamical evolution
HST PanCET Program: A Complete Near-UV to Infrared Transmission Spectrum for the Hot Jupiter WASP-79b. We present a new optical transmission spectrum of the hot Jupiter WASP-79b. We observed three transits with the STIS instrument mounted on the Hubble Space Telescope (HST), spanning 0.3-1.0 μm. Combining these transits with previous observations, we construct a complete 0.3-5.0 μm transmission spectrum of WASP-79b. Both HST and ground-based observations show decreasing transit depths toward blue wavelengths, contrary to expectations from Rayleigh scattering or hazes. We infer atmospheric and stellar properties from the full near-UV to infrared transmission spectrum of WASP-79b using three independent retrieval codes, all of which yield consistent results. Our retrievals confirm previous detections of H2O (at 4.0σ confidence) while providing moderate evidence of H- bound-free opacity (3.3σ) and strong evidence of stellar contamination from unocculted faculae (4.7σ). The retrieved H2O abundance (~1%) suggests a superstellar atmospheric metallicity, though stellar or substellar abundances remain consistent with present observations (O/H = 0.3-34× stellar). All three retrieval codes obtain a precise H- abundance constraint: log( ${X}_{{{\rm{H}}}^{-}}$ ) ≍ -8.0 ± 0.7. The potential presence of H- suggests that James Webb Space Telescope observations may be sensitive to ionic chemistry in the atmosphere of WASP-79b. The inferred faculae are ~500 K hotter than the stellar photosphere, covering ~15% of the stellar surface. Our analysis underscores the importance of observing UV-optical transmission spectra in order to disentangle the influence of unocculted stellar heterogeneities from planetary transmission spectra.

Keywords: Observational astronomy, Exoplanet atmospheric composition , Hot Jupiters, Transmission spectroscopy, Exoplanet atmospheres
Cleaning Images with Gaussian Process Regression. Many approaches to astronomical data reduction and analysis cannot tolerate missing data: corrupted pixels must first have their values imputed. This paper presents astrofix, a robust and flexible image imputation algorithm based on Gaussian process regression. Through an optimization process, astrofix chooses and applies a different interpolation kernel to each image, using a training set extracted automatically from that image. It naturally handles clusters of bad pixels and image edges and adapts to various instruments and image types. For bright pixels, the mean absolute error of astrofix is several times smaller than that of median replacement and interpolation by a Gaussian kernel. We demonstrate good performance on both imaging and spectroscopic data, including the SBIG 6303 0.4 m telescope and the FLOYDS spectrograph of Las Cumbres Observatory and the CHARIS integral-field spectrograph on the Subaru Telescope.

Keywords: Astronomical detectors, Gaussian Processes regression
The Sejong Open Cluster Survey (SOS). VII. A Photometric Study of the Young Open Cluster IC 1590. Young open clusters are ideal laboratories to understand the star formation process. We present deep UBVI and Hα photometry for the young open cluster IC 1590 in the center of the H II region NGC 281. Early-type members are selected from UBV photometric diagrams, and low-mass pre-main-sequence (PMS) members are identified by using Hα photometry. In addition, the published X-ray source list and Gaia astrometric data are also used to isolate probable members. A total of 408 stars are selected as members. The mean reddening obtained from early-type members is ⟨E(B - V)⟩ = 0.40 ± 0.06 (s.d.). We confirm the abnormal extinction law for the intracluster medium. The distance modulus to the cluster determined from the zero-age main-sequence fitting method is 12.3 ± 0.2 mag (d = 2.88 ± 0.28 kpc), which is consistent with the distance $d={2.70}_{-0.20}^{+0.24}$ kpc from the recent Gaia parallaxes. We also estimate the ages and masses of individual members by means of stellar evolutionary models. The mode of the age of PMS stars is about 0.8 Myr. The initial mass function of IC 1590 is derived. It appears to be a steeper shape (Γ = -1.49 ± 0.14) than that of the Salpeter/Kroupa initial mass function for the high-mass regime (m &gt; 1 M⊙). The signature of mass segregation is detected from the difference in the slopes of the initial mass functions for the inner ( $r\lt 2\buildrel{\,\prime}\over{.} 5$ ) and outer regions of this cluster. We finally discuss the star formation history in NGC 281.

Keywords: Initial mass function, Star forming regions, Pre-main sequence stars, Star formation, Open star clusters
VLBI Data Processing on Coronal Radio-sounding Experiments of Mars Express. The ESA's Mars Express solar corona experiments were performed at two solar conjunctions in the years 2015 and 2017 by a number of radio telescopes in the European VLBI Network. This paper presents the methods to measure the frequency and phase fluctuations of the spacecraft radio signal, and the applications to study the characteristics of the plasma turbulence effects on the signal at a single station and at multiple stations via cross correlation. The power spectra of the frequency fluctuations observed between 4.9 and 76.3 Rs have a power-law shape close to a Kolmogorov spectrum over the frequency interval νlo &lt; ν &lt; νup, where the nominal value of νlo is set to 3 mHz and νup is in the range of 0.03-0.15 Hz. The rms of the frequency fluctuations is presented as a function of the heliocentric distance. Furthermore, we analyze the variations of the electron column density fluctuations at solar offsets 4.9 Rs and 9.9 Rs and the cross-correlation products between the VLBI stations. The power density of the differential fluctuations between different stations decreases at ν &lt; 0.01 Hz. Finally, the fast flow speeds of solar wind &gt;700 km s-1 are derived from the cross correlation of frequency fluctuations at ν &lt; 0.01 Hz. The fast flow speeds of solar wind correspond to the high heliolatitude of the coronal region that the radio rays passed. The VLBI observations and analysis methods can be used to study the electron column density fluctuations and the turbulence at multiple spatial points in the inner solar wind by providing multiple lines of sight between the Earth and the spacecraft.

Keywords: Deep space probes, Very long baseline interferometry, Solar wind
Selection Functions in Astronomical Data Modeling, with the Space Density of White Dwarfs as a Worked Example. Statistical studies of cataloged object properties are central to astrophysics. But one cannot model those objects' population properties without the sample's selection function, the quantitative understanding of which objects could have ended up in such a catalog. As didactic introductions to this topic are scarce in the astrophysical literature, we provide one here, addressing the following questions: What is a selection function? On what arguments q should it depend? Over what domain must a selection function be defined? What simplifying approximations can be made? And, how is a selection function used in "modeling"? We argue that volume-complete samples, limited by the faintest objects, reflect a highly suboptimal selection function, needlessly reducing the number of bright and usually rare sample members. We illustrate these points by a worked example: github.com/gaia-unlimited/WD-selection-function, deriving the space density of white dwarfs (WDs) in the Galactic neighborhood as a function of their luminosity and color, Φ0(MG, (B - R)) in [mag-2 pc-3]. We construct a sample ${ \mathcal C }$ of 105 presumed WDs through straightforward selection cuts on the Gaia EDR3 catalog in magnitude, color, and parallax, q = (G, (B - R), ϖ). We then combine a simple model for Φ0 with this selection function's ${S}_{{ \mathcal C }}({\boldsymbol{q}})$ effective survey volume to estimate Φ0(MG, (B - R)) precisely and robustly against the detailed choices for ${S}_{{ \mathcal C }}({\boldsymbol{q}})$ . This resulting WD luminosity-color function Φ0(MG, (B - R)) differs dramatically from the initial number density distribution in the luminosity-color plane: by orders of magnitude in density and by four magnitudes in density peak location.

Keywords: Astronomy data analysis
THOR: An Algorithm for Cadence-independent Asteroid Discovery. We present "Tracklet-less Heliocentric Orbit Recovery" (THOR), an algorithm for linking of observations of Solar System objects across multiple epochs that does not require intranight tracklets or a predefined cadence of observations within a search window. By sparsely covering regions of interest in the phase space with "test orbits," transforming nearby observations over a few nights into the corotating frame of the test orbit at each epoch, and then performing a generalized Hough transform on the transformed detections followed by orbit determination filtering, candidate clusters of observations belonging to the same objects can be recovered at moderate computational cost and with little to no constraint on cadence. We validate the effectiveness of this approach by running on simulations as well as on real data from the Zwicky Transient Facility (ZTF). Applied to a short, two-week slice of ZTF observations, we demonstrate THOR can recover 97.4% of all previously known and discoverable objects in the targeted (a &gt; 1.7 au) population with five or more observations and with purity between 97.7% and 100%. This includes 10 likely new discoveries, and a recovery of an e ~ 1 comet C/2018 U1 (the comet would have been a ZTF discovery had THOR been running in 2018 when the data were taken). The THOR package and demo Jupyter notebooks are open source and available at https://github.com/moeyensj/thor.

Keywords: Sky surveys, Asteroids, Astronomy software, Trans-Neptunian objects, Comets
Chemical Composition of Outbursting Comet C/2015 ER61 (PanSTARRS). Comet C/2015 ER61 (PanSTARRS) is a long-period Oort cloud comet whose favorable approach to the inner parts of the solar system in 2017 April-May enabled us to characterize its primary volatile composition using the iSHELL spectrograph mounted on the 3 m NASA Infrared Telescope Facility (IRTF) on Maunakea, Hawaii. We used three iSHELL settings (covering ~2.8-5.2 μm) to sample fluorescent emissions from ${{\rm{H}}}_{2}$ O, OH, ${\mathrm{CH}}_{3}$ OH, HCN, ${{\rm{C}}}_{2}$ ${{\rm{H}}}_{2}$, ${\mathrm{NH}}_{3}$, CO, ${\mathrm{CH}}_{4}$, ${{\rm{C}}}_{2}$ ${{\rm{H}}}_{6}$, ${{\rm{H}}}_{2}$ CO, and OCS on multiple dates ranging from UT 2017 April 15 (shortly after its April 4 outburst) to May 13, nearly 30 days before the detection of its double nucleus. Our observations also offered the opportunity to obtain sensitive $3\sigma $ upper limits for cyanoacetylene (${\mathrm{HC}}_{3}$ N). We report rotational temperatures (${T}_{\mathrm{rot}}$ ), production rates (Qs), abundance (mixing) ratios (relative to ${{\rm{H}}}_{2}{\rm{O}}$ and ${{\rm{C}}}_{2}$ ${{\rm{H}}}_{6}$ ), and spatial distributions in the coma. ER61 exhibits variability in production rates of many species on short (day-to-day) and long (pre- versus post-perihelion) timescales. The relative abundances of these volatile species remained consistent within uncertainties during our pre-perihelion observations but tended to decrease during our post-perihelion observations (with the exception of ${\mathrm{CH}}_{3}$ OH and HCN). The short-timescale variability in the production rates of these volatiles could be due to diurnal effects (over the course of the rotation of the nucleus) and/or the effect of its outburst. The decrease in the production rates and hence the mixing ratios in some volatiles in post-perihelion dates could be due to the presence of seasonal effects in ER61.

Keywords: High resolution spectroscopy, Long period comets, Comet volatiles , Near infrared astronomy
A Gaia-based Photometric and Kinematic Analysis of the Old Open Cluster King 11. This paper presents an investigation of an old age open cluster King 11 using Gaia's Early Data Release 3 data. Considering the stars with membership probability (Pμ) &gt; 90%, we identified 676 most probable cluster members within the cluster's limiting radius. The mean proper motion for King 11 is determined as: μx = - 3.391 ± 0.006 and μy = - 0.660 ± 0.004 mas yr-1. The blue straggler stars of King 11 show a centrally concentrated radial distribution. The values of limiting radius, age, and distance are determined as 18'51, 3.63 ± 0.42 Gyr, and 3.33 ± 0.15 kpc, respectively. The cluster's apex coordinates (A = 267°84 ± 1°01, D = - 27°48 ± 1°03) are determined using the apex diagram method and verified using the (μU, μT) diagram. We also obtained the orbit that the cluster follows in the Galaxy and estimated its tentative birthplace in the disk. The resulting spatial velocity of King 11 is 60.2 ± 2.16 km s-1. A significant oscillation along the Z coordinate up to 0.556 ± 0.022 kpc is determined.

Keywords: Stellar kinematics, Orbits, Open star clusters, Apex, Astrometry, Hertzsprung Russell diagram
Rotation Periods of TESS Objects of Interest from the Magellan-TESS Survey with Multiband Photometry from Evryscope and TESS. Stellar radial-velocity (RV) jitter due to surface activity may bias the RV semiamplitude and mass of rocky planets. The amplitude of the jitter may be estimated from the uncertainty in the rotation period, allowing the mass to be more accurately obtained. We find candidate rotation periods for 17 out of 35 TESS Objects of Interest (TOI) hosting &lt;3 R⊕ planets as part of the Magellan-TESS survey, which is the first-ever statistically robust study of exoplanet masses and radii across the photoevaporation gap. Seven periods are ≥3σ detections, two are ≥1.5σ, and eight show plausible variability, but the periods remain unconfirmed. The other 18 TOIs are nondetections. Candidate rotators include the host stars of the confirmed planets L 168-9 b, the HD 21749 system, LTT 1445 A b, TOI 1062 b, and the L 98-59 system. Thirteen candidates have no counterpart in the 1000 TOI rotation catalog of Canto Martins et al. We find periods for G3-M3 dwarfs using combined light curves from TESS and the Evryscope all-sky array of small telescopes, sometimes with longer periods than would be possible with TESS alone. Secure periods range from 1.4 to 26 days with Evryscope-measured photometric amplitudes as small as 2.1 mmag in $g^{\prime} $ . We also apply Monte Carlo sampling and a Gaussian process stellar activity model from exoplanet to the TESS light curves of six TOIs to confirm the Evryscope periods.

Keywords: Starspots, Sky surveys, Stellar activity, Exoplanet astronomy, Radial velocity
Detection and Bulk Properties of the HR 8799 Planets with High-resolution Spectroscopy. Using the Keck Planet Imager and Characterizer, we obtained high-resolution (R ~ 35,000) K-band spectra of the four planets orbiting HR 8799. We clearly detected H2O and CO in the atmospheres of HR 8799 c, d, and e, and tentatively detected a combination of CO and H2O in b. These are the most challenging directly imaged exoplanets that have been observed at high spectral resolution to date when considering both their angular separations and flux ratios. We developed a forward-modeling framework that allows us to jointly fit the spectra of the planets and the diffracted starlight simultaneously in a likelihood-based approach and obtained posterior probabilities on their effective temperatures, surface gravities, radial velocities, and spins. We measured $v\sin (i)$ values of ${10.1}_{-2.7}^{+2.8}\,\mathrm{km}\,{{\rm{s}}}^{-1}$ for HR 8799 d and ${15.0}_{-2.6}^{+2.3}\,\mathrm{km}\,{{\rm{s}}}^{-1}$ for HR 8799 e, and placed an upper limit of &lt;14 km s-1 of HR 8799 c. Under two different assumptions of their obliquities, we found tentative evidence that rotation velocity is anticorrelated with companion mass, which could indicate that magnetic braking with a circumplanetary disk at early times is less efficient at spinning down lower-mass planets.

Keywords: High resolution spectroscopy, Exoplanet formation, High angular resolution, Exoplanet atmospheres