Sazuna/UAT_keywords huggingface dataset:
Stellar Rotation and Structure of the α Persei Complex: When Does Gyrochronology Start to Work?. On the pre-main sequence, the rotation rates of Sun-like stars are dictated by the interplay between the protostellar disk and the star's contraction. At ages exceeding 100 Myr, magnetic spindown erases the initial stellar spin rate and enables rotation-based age dating (gyrochronology). The exact time at which the transition between these two regimes occurs depends on stellar mass, and has been challenging to empirically resolve due to a lack of viable calibration clusters. The α Persei open cluster (t ≈ 80 Myr, d ≈ 170 pc) may provide the needed calibrator, but recent analyses of the Gaia data have provided wildly varying views of its age and spatial extent. As such, we analyze a combination of TESS, Gaia, and LAMOST data to calibrate gyrochronology at the age of α Per and to uncover the cluster's true morphology. By assembling a list of rotationally confirmed α Per members, we provide strong evidence that α Per is part of a larger complex of similarly aged stars. Through kinematic back-integration, we show that the most diffuse components of α Per were five times closer together 50 Myr ago. Finally, we use our stellar rotation periods to derive a relative gyrochronology age for α Per of 67% ± 12% the age of the Pleiades, which yields 86 ± 16 Myr given current knowledge. We show that by this age, stars more massive than ≈0.8 M ⊙ have converged to form a well-defined slow sequence.

Keywords: Open star clusters, Stellar rotation, Clustering, Stellar ages
Detecting Exoplanets Closer to Stars with Moderate Spectral Resolution Integral-field Spectroscopy. While radial velocity surveys have demonstrated that the population of gas giants peaks around 3 au, the most recent high-contrast imaging surveys have only been sensitive to planets beyond ~10 au. Sensitivity at small angular separations from stars is currently limited by the variability of the point-spread function. We demonstrate how moderate-resolution integral-field spectrographs can detect planets at smaller separations (≲ 0.3") by detecting the distinct spectral signature of planets compared to the host star. Using OSIRIS (R ≈ 4000) at the W.M. Keck Observatory, we present the results of a planet search via this methodology around 20 young targets in the Ophiuchus and Taurus star-forming regions. We show that OSIRIS can outperform high-contrast coronagraphic instruments equipped with extreme adaptive optics and non-redundant masking in the 0.05"-0.3" regime. As a proof of concept, we present the 34σ detection of a high-contrast M dwarf companion at ≈0.1" with flux ratio of ≈ 0.92% around the field F2 star HD 148352. We developed an open-source Python package, breads, for the analysis of moderate-resolution integral-field spectroscopy data in which the planet and the host star signal are jointly modeled. The diffracted starlight continuum is forward-modeled using a spline model, which removes the need for prior high-pass filtering or continuum normalization. The code allows for analytic marginalization of linear hyperparameters, which simplifies the posterior sampling of other parameters (e.g., radial velocity, effective temperature). This technique could prove very powerful when applied to integral-field spectrographs such as NIRSpec on the JWST and other upcoming first-light instruments on the future Extremely Large Telescopes.

Keywords: High contrast techniques, Exoplanet detection methods, High resolution spectroscopy, Direct imaging
Active Stars in the Spectroscopic Survey of Mid-to-late M Dwarfs within 15 pc. We present results from the volume-complete spectroscopic survey of 0.1-0.3 M ⊙ M dwarfs within 15 pc. This work discusses the active sample without close binary companions, providing a comprehensive picture of these 123 stars with Hα emission stronger than -1 Å. Our analysis includes rotation periods (including 31 new measurements), Hα equivalent widths, rotational broadening, inclinations, and radial velocities, determined using high-resolution, multiepoch spectroscopic data from the TRES and CHIRON spectrographs supplemented by photometry from TESS and MEarth. Using this volume-complete sample, we establish that the majority of active, low-mass M dwarfs are very rapid rotators: specifically, 74% ± 4% have rotation periods shorter than 2 days, while 19% ± 4% have intermediate rotation periods of 2-20 days, and the remaining 8% ± 3% have periods longer than 20 days. Among the latter group, we identify a population of stars with very high Hα emission, which we suggest is indicative of dramatic spindown as these stars transition from the rapidly rotating mode to the slowly rotating one. We are unable to determine rotation periods for six stars and suggest that some of the stars without measured rotation periods may be viewed pole-on, as such stars are absent from the distribution of inclinations we measure; this lack notwithstanding, we recover the expected isotropic distribution of spin axes. Our spectroscopic and photometric data sets also allow us to investigate activity-induced radial-velocity variability, which we show can be estimated as the product of rotational broadening and the photometric amplitude of spot modulation.

Keywords: M dwarf stars, Inclination, Stellar activity, Variable stars, Radial velocity, Stellar rotation
Imaging the Milky Way with Millihertz Gravitational Waves. Modern astronomers enjoy access to all-sky images across a wide range of the electromagnetic spectrum from long-wavelength radio to high-energy gamma rays. The most prominent feature in many of these images is our own Galaxy, with different features revealed in each wave band. Gravitational waves (GWs) have recently been added to the astronomers' toolkit as a nonelectromagnetic messenger. To date, all identified GW sources have been extra-Galactic and transient. However, the Milky Way hosts a population of ultracompact binaries (UCBs), which radiate persistent GWs in the milliHertz band that is not observable with today's terrestrial gravitational-wave detectors. Space-based detectors such as the Laser Interferometer Space Antenna will measure this population and provide a census of their location, masses, and orbital properties. In this work, we will show how this data can be used to form a false-color image of the Galaxy that represents the intensity and frequency of the gravitational waves produced by the UCB population. Such images can be used to study the morphology of the Galaxy, identify interesting multimessenger sources through cross-matching, and for educational and outreach purposes.

Keywords: White dwarf stars, Compact binary stars, Gravitational wave astronomy, Gravitational waves, Astronomy image processing
The Absolute Age of M92. The absolute age of a simple stellar population is of fundamental interest for a wide range of applications but is difficult to measure in practice, as it requires an understanding of the uncertainties in a variety of stellar evolution processes as well as the uncertainty in the distance, reddening, and composition. As a result, most studies focus only on the relative age by assuming that stellar evolution calculations are accurate and using age determinations techniques that are relatively independent of distance and reddening. Here, we construct 20,000 sets of theoretical isochrones through Monte Carlo simulation using the Dartmouth Stellar Evolution Program to measure the absolute age of the globular cluster M92. For each model, we vary a range of input physics used in the stellar evolution models, including opacities, nuclear reaction rates, diffusion coefficients, atmospheric boundary conditions, helium abundance, and treatment of convection. We also explore variations in the distance and reddening as well as its overall metallicity and α enhancement. We generate simulated Hess diagrams around the main-sequence turn-off region from each set of isochrones and use a Voronoi binning method to fit the diagrams to Hubble Space Telescope Advanced Camera for Surveys data. We find the age of M92 to be 13.80 ± 0.75 Gyr. The 5.4% error in the absolute age is dominated by the uncertainty in the distance to M92 (~80% of the error budget); of the remaining parameters, only the total metallicity, α element abundance, and treatment of helium diffusion contribute significantly to the total error.

Keywords: Globular star clusters, Stellar physics, Computational astronomy, Stellar evolutionary models
Serverless Architecture for Data Processing and Detecting Anomalies with the Mars Express MARSIS Instrument. The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on board Mars Express has been sampling the topside ionosphere of Mars since mid-2005. The analysis of the main reflection (nadir) of the ionosphere through the ionograms provided by the MARSIS instrument is typically performed manually due to the high noise level in the lower frequencies. This task, which involves pattern recognition, turns out to be unfeasible for the &gt;2 million ionograms available at the European Planetary Science Archive. In the present contribution, we propose a modular architecture based on serverless computing (a paradigm that stands on the cloud) for optimal processing of these ionograms. In particular, we apply serverless computing to detect oblique echoes in the ionosphere, which are nonnadir reflections produced when MARSIS is sounding regions above or nearby crustal magnetic fields, where the ionosphere loses the spherical symmetry. Oblique echoes are typically observed at similar frequencies to the nadir reflections but at different times delays, sometimes even overlaying the nadir reflection. Oblique echoes are difficult to analyze with the standard technique due to their nonconstant and highly variable appearance, but they harbor essential information on the state of the ionosphere over magnetized regions. In this work we compare the proposed serverless architecture with two local alternatives while processing a representative data subset and finally provide a study by means of cost and performance.

Keywords: Mars, Planetary ionospheres
Measuring the Cosmic X-Ray Background in 3-20 KeV with Stray Light from NuSTAR. By characterizing the contribution of stray light to large data sets from the CXB Measurement X-ray observatory collected over 2012-2017, we report a measurement of the cosmic X-ray background (CXB) in the 3-20 keV energy range. These data represent ~20% sky coverage while avoiding Galactic ridge X-ray emission and are less weighted by deep survey fields than previous measurements with CXB Measurement. Images in narrow energy bands are stacked in detector space and spatially fit with a model representing the stray light and uniform pattern expected from the CXB and the instrumental background, respectively. We establish baseline flux values from Earth-occulted data and validate the fitting method on stray-light observations of the Crab, which further serve to calibrate the resulting spectra. We present independent spectra of the CXB with the focal plane module FPMA and FPMB detector arrays, which are in excellent agreement with the canonical characterization by HEAO 1 and are 10% lower than most subsequent measurements: ${F}_{3-20\,\mathrm{keV}}^{\mathrm{FPMA}}=2.63\times {10}^{-11}\,\mathrm{erg}\,{{\rm{s}}}^{-1}\,{\mathrm{cm}}^{-2}\,{\deg }^{-2}$ and ${F}_{3\mbox{--}20\,\mathrm{keV}}^{\mathrm{FPMB}}\,=2.58\times {10}^{-11}\,\mathrm{erg}\,{{\rm{s}}}^{-1}\,{\mathrm{cm}}^{-2}\,{\deg }^{-2}$ . We discuss these results in light of previous measurements of the CXB and consider the impact of systematic uncertainties on our spectra.

Keywords: Astronomy data analysis, Active galactic nuclei, X-ray surveys, Diffuse x-ray background, Cosmic background radiation
Luminosity Outburst Energized by the Collision between the Infalling Streamer and Disk in W51 North. We report the detection of the disk/torus, outflow, and inflow structures traced by H2O masers toward a high-mass young stellar object W51 North during its H2O maser outburst stage using the Karl G. Jansky Very Large Array (VLA). It is found that the disk has a radius of ~4000 au and an inclination angle with respect to the sky plane of ~60° by combining the VLA and the Atacama Large Millimeter/submillimeter Array data. Additionally, a peculiar flow perpendicular to the SiO bipolar outflow is detected in the H2O maser, SiO, and HC3N lines, which is newly-identified as an infalling streamer rather than an old outflow from this source, as reported in previous studies. Combining the VLA map and the Tianma radio telescope monitoring of the H2O masers suggests that the origin of the luminosity outburst of H2O masers during 2020 January-April is likely related to the energy release from the collision between the infalling streamer and the disk. This may provide an additional mechanism to account for the luminosity outburst or episodic accretion beyond disk fragmentation caused by gravitational instability.

Keywords: Young stellar objects, Star formation, Astrophysical masers, Interstellar masers, Stellar accretion disks, Protostars
The Hitchhiker's Guide to the Galaxy Catalog Approach for Dark Siren Gravitational-wave Cosmology. We outline the "dark siren" galaxy catalog method for cosmological inference using gravitational wave (GW) standard sirens, clarifying some common misconceptions in the implementation of this method. When a confident transient electromagnetic counterpart to a GW event is unavailable, the identification of a unique host galaxy is in general challenging. Instead, as originally proposed by Schutz, one can consult a galaxy catalog and implement a dark siren statistical approach incorporating all potential host galaxies within the localization volume. Trott &amp; Huterer recently claimed that this approach results in a biased estimate of the Hubble constant, H 0, when implemented on mock data, even if optimistic assumptions are made. We demonstrate explicitly that, as previously shown by multiple independent groups, the dark siren statistical method leads to an unbiased posterior when the method is applied to the data correctly. We highlight common sources of error possible to make in the generation of mock data and implementation of the statistical framework, including the mismodeling of selection effects and inconsistent implementations of the Bayesian framework, which can lead to a spurious bias.

Keywords: Gravitational wave astronomy, Cosmology, Hubble constant
Estimation of the Flux at 1450 MHz of OB Stars for FAST and SKA. Radio observation is crucial to understanding the wind mechanism of OB stars but very scarce. This work estimates the flux at 1450 MHz (S 1.4GHz) of about 5000 OB stars identified by the LAMOST spectroscopic survey and confirmed by the Gaia astrometric as well as astrophysical measurements. The calculation is performed under the free-free emission mechanism for wind with the mass-loss rate derived from stellar parameters. The estimated S 1.4GHz distributes from 10-11 to 10-3 Jy with the peak at about 10-8 Jy. This implies that the complete SKA-II can detect more than half of them, and some tens of objects are detectable by FAST without considering source confusion. An array of FAST would increase the detectable sample by 2 orders of magnitude.

Keywords: Radio continuum emission, OB stars, Stellar winds, Radio telescopes
Wavelength-dependent Extinction and Grain Sizes in "Dippers". We have examined internight variability of K2-discovered "dippers" that are not close to being viewed edge-on, as determined from previously reported ALMA images, using the SpeX spectrograph on NASA's Infrared Telescope Facility. The three objects observed were EPIC 203850058, EPIC 205151387, and EPIC 204638512 (=2MASS J16042165-2130284). Using the ratio of the fluxes between two successive nights, we find that for EPIC 204638512 and EPIC 205151387, we find that the properties of the dust differ from that seen in the diffuse interstellar medium and denser molecular clouds. However, the grain properties needed to explain the extinction does resemble those used to model the disks of many young stellar objects. The wavelength-dependent extinction models of both EPIC 204638512 and EPIC 205151387 includes grains at least 500 μm in size, but lacks grains smaller than 0.25 μm. The change in extinction during the dips, and the timescale for these variations to occur, imply obscuration by the surface layers of the inner disks. The recent discovery of a highly misinclined inner disk in EPIC 204638512 is suggests that the variations in this disk system may point to due to rapid changes in obscuration by the surface layers of its inner disk, and that other "face-on" dippers might have similar geometries. The He I line at 1.083 μm in EPIC 205151387 and EPIC 20463851 were seen to change from night to night, suggesting that we are seeing He I gas mixed in with the surface dust.

Keywords: Protostars, Circumstellar dust, Protoplanetary disks
The Spitzer Coverage of HSC-Deep with IRAC for Z studies (SHIRAZ). I. IRAC Mosaics. We present new Spitzer Infrared Array Camera (IRAC) 3.6 and 4.5 μm mosaics of three fields, E-COSMOS, DEEP2-F3, and ELAIS-N1. Our mosaics include both new IRAC observations as well as reprocessed archival data in these fields. These fields are part of the HSC-Deep grizy survey and have a wealth of additional ancillary data. The addition of these new IRAC mosaics is critical in allowing for improved photometric redshifts and stellar population parameters at cosmic noon and earlier epochs. The total area mapped by this work is ~17 deg2 with a mean integration time of ≈1200s, providing a median 5σ depth of 23.7(23.3) at 3.6(4.5) μm in AB. We perform SExtractor photometry both on the combined mosaics as well as the single-epoch mosaics taken ≈6 months apart. The resultant IRAC number counts show good agreement with previous studies. In combination with the wealth of existing and upcoming spectrophotometric data in these fields, our IRAC mosaics will enable a wide range of galactic evolution and AGN studies. With that goal in mind, we make the combined IRAC mosaics and coverage maps of these three fields publicly available.

Keywords: Astronomy data analysis, Astronomy data acquisition
Point Source C-band Mueller Matrices for the Green Bank Telescope. C-band Mueller matrices for the Green Bank Telescope are presented here which enable on-sky Stokes parameters for point sources at the beam center to be determined. Standard calibrators, 3C 138 and 3C 286, were observed using the Spider program to steer the telescope across a broad range of R.A. on both sides of the zenith transit. For this analysis, only the observations at the peak of the Spider pattern were used rather than the full sweep of the runs. Therefore, the results presented here only apply to point sources at the beam center. The Mueller matrices are shown to vary with frequency and with use of the Hi-Cal or Lo-Cal noise diodes, due to the relative calibration gain between the X and Y components of the feed. However, the relative calibration gain can be determined from observations of a source with known polarization. Correcting the data for the relative calibration gain prior to data analysis allows for use of a frequency-independent Mueller matrix. This generic Mueller matrix is shown to provide reliable C-band polarization measurements.

Keywords: Software documentation, Calibration, Radio telescopes, Astronomical instrumentation, Polarimetry
The 14 Her Planetary System: Companion Masses and Architecture from Radial Velocities and Astrometry. We combine Hubble Space Telescope (HST) Fine Guidance Sensor, Hipparcos, and Gaia DR3 astrometric observations of the K0 V star 14 Her with the results of an analysis of extensive ground-based radial velocity data to determine perturbation orbits and masses for two previously known companions, 14 Her b and c. Radial velocities obtained with the Hobby-Eberly Telescope and from the literature now span over 25 years. With these data we obtain improved radial velocity (RV) orbital elements for both the inner companion, 14 Her b and the long-period outer companion, 14 Her c. We also find evidence of an additional RV signal with P ~ 3789d. We then model astrometry from Hipparcos, HST, and Gaia with RV results to obtain system parallax and proper motion, perturbation periods, inclinations, and sizes due to 14 Her b and c. We find P b = 1767.6 ± 0.2 days, perturbation semimajor axis α b = 1.3 ± 0.1 mas, and inclination i b = 36° ± 3°, P c = 52160 ± 1028 days, perturbation semimajor axis α c = 10.3 ± 0.7 mas, and inclination i c = 82° ± 14°. In agreement with a past investigation, the 14 Her b, c orbits exhibit significant mutual inclination. Assuming a primary mass M * = 0.98 ± 0.04M ⊙, we obtain companion masses ${{ \mathcal M }}_{{\rm{b}}}={8.5}_{-0.8}^{+1.0}$ ${{ \mathcal M }}_{\mathrm{Jup}}\,$ and ${{ \mathcal M }}_{{\rm{c}}}={7.1}_{-0.6}^{+1.0}$ ${{ \mathcal M }}_{\mathrm{Jup}}$ .

Keywords: Exoplanets
Multiplicity Boost of Transit Signal Classifiers: Validation of 69 New Exoplanets using the Multiplicity Boost of ExoMiner. Most existing exoplanets are discovered using validation techniques rather than being confirmed by complementary observations. These techniques generate a score that is typically the probability of the transit signal being an exoplanet (y(x) = exoplanet) given some information related to that signal (represented by x). Except for the validation technique in Rowe et al. (2014), which uses multiplicity information to generate these probability scores, the existing validation techniques ignore the multiplicity boost information. In this work, we introduce a framework with the following premise: given an existing transit-signal vetter (classifier), improve its performance using multiplicity information. We apply this framework to several existing classifiers, which include vespa, Robovetter, AstroNet, ExoNet, GPC and RFC, and ExoMiner, to support our claim that this framework is able to improve the performance of a given classifier. We then use the proposed multiplicity boost framework for ExoMiner V1.2, which addresses some of the shortcomings of the original ExoMiner classifier, and validate 69 new exoplanets for systems with multiple Kepler Objects of Interests from the Kepler catalog.

Keywords: Exoplanet catalogs, Exoplanets, Neural networks, Convolutional neural networks, Exoplanet systems, Exoplanet astronomy, Exoplanet detection methods
Precise Age for the Binary Star System 12 Com in the Coma Berenices Cluster. We present measurements of the interferometrically resolved binary star system 12 Com and the single giant star 31 Com in the cluster Coma Berenices. 12 Com is a double-lined spectroscopic binary system consisting of a G7 giant and an A3 dwarf at the cluster turnoff. Using an extensive radial velocity data set and interferometric measurements from the Palomar Testbed Interferometer and the Center for High Angular Resolution Astronomy array, we measured masses M 1 = 2.64 ± 0.07M ⊙ and M 2 = 2.10 ± 0.03M ⊙. Interferometry also allows us to resolve the giant and measure its size as R 1 = 9.12 ± 0.12 ± 0.01R ⊙. With the measured masses and radii, we find an age of 533 ± 41 ± 42 Myr. For comparison, we measure the radius of 31 Com to be 8.36 ± 0.15 R ⊙. Based on the photometry and radius measurements, 12 Com A is likely the most evolved bright star in the cluster, large enough to be in the red giant phase, but too small to have core helium burning. Simultaneous knowledge of 12 Com A's mass and photometry puts strong constraints on convective core overshooting during the main-sequence phase, which in turn reduces systematic uncertainties in the age. Increased precision in measuring this system also improves our knowledge of the progenitor of the cluster white dwarf WD1216+260.

Keywords: Stellar ages, White dwarf stars, Open star clusters, Spectroscopic binary stars, Interferometric binary stars, Stellar evolution