Sazuna/UAT_keywords huggingface dataset:
Stellar Properties for a Comprehensive Collection of Star-forming Regions in the SDSS APOGEE-2 Survey. The Sloan Digital Sky Survey IV APOGEE-2 primary science goal was to observe red giant stars throughout the Galaxy to study its dynamics, morphology, and chemical evolution. The APOGEE instrument, a high-resolution 300-fiber H-band (1.55-1.71 μm) spectrograph, is also ideal to study other stellar populations in the Galaxy, among which are a number of star-forming regions and young open clusters. We present the results of the determination of six stellar properties (T eff, $\mathrm{log}\,g$ , [Fe/H], L/L ⊙, M/M ⊙, and age) for a sample that is composed of 3360 young stars, of subsolar to supersolar types, in 16 Galactic star formation and young open cluster regions. Those sources were selected by using a clustering method that removes most of the field contamination. Samples were also refined by removing targets affected by various systematic effects of the parameter determination. The final samples are presented in a comprehensive catalog that includes all six estimated parameters. This overview study also includes parameter spatial distribution maps for all regions and Hertzsprung-Russell ( $\mathrm{log}L/{L}_{\odot }$ vs. T eff) diagrams. This study serves as a guide for detailed studies on individual regions and paves the way for the future studies on the global properties of stars in the pre-main-sequence phase of stellar evolution using more robust samples. * Based on SDSS Data Releases 16 and 17.

Keywords: Fundamental parameters of stars, Star forming regions, Young star clusters, Pre-main sequence stars, Near infrared astronomy
Li-rich Giants Identified from LAMOST DR8 Low-resolution Survey. A small fraction of giants possess photospheric lithium (Li) abundance higher than the value predicted by the standard stellar evolution models, and the detailed mechanisms of Li enhancement are complicated and lack a definite conclusion. In order to better understand the Li enhancement behaviors, a large and homogeneous Li-rich giant sample is needed. In this study, we designed a modified convolutional neural network model called Coord-DenseNet to determine the A(Li) of Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) low-resolution survey (LRS) giant spectra. The precision is good on the test set: MAE = 0.15 dex, and σ = 0.21 dex. We used this model to predict the Li abundance of more than 900,000 LAMOST DR8 LRS giant spectra and identified 7768 Li-rich giants with Li abundances ranging from 2.0 to 5.4 dex, accounting for about 1.02% of all giants. We compared the Li abundance estimated by our work with those derived from high-resolution spectra. We found that the consistency was good if the overall deviation of 0.27 dex between them was not considered. The analysis shows that the difference is mainly due to the high A(Li) from the medium-resolution spectra in the training set. This sample of Li-rich giants dramatically expands the existing sample size of Li-rich giants and provides us with more samples to further study the formation and evolution of Li-rich giants.

Keywords: Chemically peculiar giant stars, Stellar abundances, Chemical abundances, Chemical enrichment, Stellar evolution
Photometry of the Four Anti-Galactocentric Old Open Clusters: Czernik 30, Berkeley 34, Berkeley 75, and Berkeley 76. We present a BVI photometric study of four old open clusters (OCs) in the the Milky Way, Czernik 30, Berkeley 34, Berkeley 75, and Berkeley 76 using the observation data obtained with the Small and Moderate Aperture Research Telescope System 1.0 m telescope at the Cerro Tololo Inter-American Observatory, Chile. These four OCs are located at the anti-Galactocentric direction and in the Galactic plane. We determine the fundamental physical parameters for the four OCs, such as age, metallicity, distance modulus, and color excess, using red clump and PARSEC isochrone fitting methods after finding center and size of the four OCs. These four old OCs are 2-3 Gyr old and 6-8 kpc away from the Sun. The metallicity ([Fe/H]) values of the four OCs are between -0.6 and 0.0 dex. We combine data for these four OCs with those for old OCs from five literatures resulting in 236 objects to investigate Galactic radial-metallicity distribution. The gradient of a single linear fit for this Galactocentric [Fe/H] distribution is -0.052 ± 0.004 dex kpc-1. If we assume the existence of a discontinuity in this radial-metallicity distribution, the gradient at Galactocentric radius &lt;12 kpc is -0.070 ± 0.006 dex kpc-1, while that at the outer part is -0.016 ± 0.010 which is flatter than that of the inner part. Although there are not many sample clusters at the outer part, the broken linear fit seems to better follow the observation data.

Keywords: Red giant clump, Open star clusters, Galaxy disks
Eliminating Massive Martian Dust Storms from Images of Tianwen-1 via Deep Learning. Dust storms may remarkably degrade the imaging quality of Martian orbiters and delay the progress of mapping the global topography and geomorphology. To address this issue, this paper presents an approach that reuses the image dehazing knowledge obtained on Earth to resolve the dust-removal problem on Mars. In this approach, we collect remote-sensing images captured by Tianwen-1 and manually select hundreds of clean and dusty images. Inspired by the haze formation process on Earth, we formulate a similar visual degradation process on clean images and synthesize dusty images sharing a similar feature distribution with realistic dusty images. These realistic clean and synthetic dusty image pairs are used to train a deep model that inherently encodes the irrelevant features of dust and decodes them into dust-free images. Qualitative and quantitative results show that dust storms can be effectively eliminated by the proposed approach, leading to obviously improved topographical and geomorphological details of Mars.

Keywords: Mars, Martian satellites
Detailed Chemical Abundances of Stars in the Outskirts of the Tucana II Ultrafaint Dwarf Galaxy. We present chemical abundances and velocities of five stars between 0.3 and 1.1 kpc from the center of the Tucana II ultrafaint dwarf galaxy (UFD) from high-resolution Magellan/MIKE spectroscopy. We find that every star is deficient in metals (-3.6 &lt; [Fe/H] &lt; -1.9) and in neutron-capture elements as is characteristic of UFD stars, unambiguously confirming their association with Tucana II. Other chemical abundances (e.g., C, iron peak) largely follow UFD trends and suggest that faint core-collapse supernovae (SNe) dominated the early evolution of Tucana II. We see a downturn in [α/Fe] at [Fe/H] ≈ -2.8, indicating the onset of Type Ia SN enrichment and somewhat extended chemical evolution. The most metal-rich star has strikingly low [Sc/Fe] = -1.29 ± 0.48 and [Mn/Fe] = -1.33 ± 0.33, implying significant enrichment by a sub-Chandrasekhar mass Type Ia SN. We do not detect a radial velocity gradient in Tucana II ( ${{dv}}_{\mathrm{helio}}/d{\theta }_{1}=-{2.6}_{-2.9}^{+3.0}$ km s-1 kpc-1), reflecting a lack of evidence for tidal disruption, and derive a dynamical mass of ${M}_{1/2}\,({r}_{h})={1.6}_{-0.7}^{+1.1}\times {10}^{6}$ M ⊙. We revisit formation scenarios of the extended component of Tucana II in light of its stellar chemical abundances. We find no evidence that Tucana II had abnormally energetic SNe, suggesting that if SNe drove in situ stellar halo formation, then other UFDs should show similar such features. Although not a unique explanation, the decline in [α/Fe] is consistent with an early galactic merger triggering later star formation. Future observations may disentangle such formation channels of UFD outskirts. * This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Keywords: Local Group, Population II stars, Dwarf galaxies
MAVEN Observations of Whistler-mode Waves Within the Magnetic Dips in the Martian Ionopause/Ionosphere. Whistler-mode waves are natural and common electromagnetic emissions observed both surrounding planets and their moons with and without intrinsic magnetic field. Numerous observations have shown that the magnetic dip is a favorable region for the whistler-mode wave generation in the Earth's magnetosphere. However, up to now, seldom observations of these waves have been reported in such regions at Mars. Based on the measurements from Mars Atmosphere and Volatile EvolutioN mission, quasi-parallel propagating whistler-mode waves are observed within magnetic dip structures in the Martian ionopause and ionosphere. Correspondingly, significant electron beams in the antiparallel direction are observed, and a linear instability analysis shows that f pe/f ce becomes extremely large (~1500) inside the magnetic dip. Thus, the electron minimum resonant energy of whistler-mode waves decreases to several eV, which increases the number density of resonant beam electrons. Such beam electron distribution results in the necessary free energy for the whistler-mode wave growth. Our study indicates magnetic dips may be favorable regions for the whistler-mode wave excitation even in the Martian ionosphere, which has an extremely high f pe/f ce but does not have a global intrinsic magnetic field.

Keywords: Space plasmas, Planetary magnetospheres, Magnetospheric radio emissions
The Giant Accreting Protoplanet Survey (GAPlanetS): Optimization Techniques for Robust Detections of Protoplanets. High-contrast imaging has afforded astronomers the opportunity to study light directly emitted by adolescent (tens of megayears) and "proto" (&lt;10 Myr) planets still undergoing formation. Direct detection of these planets is enabled by empirical point-spread function (PSF) modeling and removal algorithms. The computational intensity of such algorithms, as well as their multiplicity of tunable input parameters, has led to the prevalence of ad hoc optimization approaches to high-contrast imaging results. In this work, we present a new, systematic approach to optimization vetted using data of the high-contrast stellar companion HD 142527 B from the Magellan Adaptive Optics Giant Accreting Protoplanet Survey (GAPlanetS). More specifically, we present a grid search technique designed to explore three influential parameters of the PSF subtraction algorithm pyKLIP: annuli, movement, and KL modes. We consider multiple metrics for postprocessed image quality in order to optimally recover at Hα (656 nm) synthetic planets injected into contemporaneous continuum (643 nm) images. These metrics include peak (single-pixel) signal-to-noise ratio (S/N), average (multipixel average) S/N, 5σ contrast, and false-positive fraction. We apply continuum-optimized KLIP reduction parameters to six Hα direct detections of the low-mass stellar companion HD 142527 B and recover the companion at a range of separations. Relative to a single-informed, nonoptimized set of KLIP parameters applied to all data sets uniformly, our multimetric grid search optimization led to improvements in companion S/N of up to 1.2σ, with an average improvement of 0.6σ. Since many direct imaging detections lie close to the canonical 5σ threshold, even such modest improvements may result in higher yields in future imaging surveys.

Keywords: Principal component analysis, Exoplanet detection methods, Direct imaging, Astronomy data analysis
Target Selection and Validation of DESI Luminous Red Galaxies. The Dark Energy Spectroscopic Instrument (DESI) is carrying out a five-year survey that aims to measure the redshifts of tens of millions of galaxies and quasars, including 8 million luminous red galaxies (LRGs) in the redshift range 0.4 &lt; z ≲ 1.0. Here we present the selection of the DESI LRG sample and assess its spectroscopic performance using data from Survey Validation (SV) and the first two months of the Main Survey. The DESI LRG sample, selected using g, r, z, and W1 photometry from the DESI Legacy Imaging Surveys, is highly robust against imaging systematics. The sample has a target density of 605 deg-2 and a comoving number density of 5 × 10-4 h 3 Mpc-3 in 0.4 &lt; z &lt; 0.8; this is a significantly higher density than previous LRG surveys (such as SDSS, BOSS, and eBOSS) while also extending to z ~ 1. After applying a bright star veto mask developed for the sample, 98.9% of the observed LRG targets yield confident redshifts (with a catastrophic failure rate of 0.2% in the confident redshifts), and only 0.5% of the LRG targets are stellar contamination. The LRG redshift efficiency varies with source brightness and effective exposure time, and we present a simple model that accurately characterizes this dependence. In the appendices, we describe the extended LRG samples observed during SV.

Keywords: Cosmology, Redshift surveys
Speckle Space-Time Covariance in High-contrast Imaging. We introduce a new framework for point-spread function subtraction based on the spatiotemporal variation of speckle noise in high-contrast imaging data where the sampling timescale is faster than the speckle evolution timescale. One way that space-time covariance arises in the pupil is as atmospheric layers translate across the telescope aperture and create small, time-varying perturbations in the phase of the incoming wavefront. The propagation of this field to the focal plane preserves some of that space-time covariance. To utilize this covariance, our new approach uses a Karhunen-Loève transform on an image sequence, as opposed to a set of single reference images as in previous applications of Karhunen-Loève Image Processing (KLIP) for high-contrast imaging. With the recent development of photon-counting detectors, such as microwave kinetic inductance detectors, this technique now has the potential to improve contrast when used as a post-processing step. Preliminary testing on simulated data shows this technique can improve contrast by at least 10%-20% from the original image, with significant potential for further improvement. For certain choices of parameters, this algorithm may provide larger contrast gains than spatial-only KLIP.

Keywords: Observational astronomy, Infrared astronomy, Astronomical techniques, Coronagraphic imaging, Direct imaging, Ground-based astronomy, Exoplanet detection methods, Astronomical methods, Astronomy data reduction
TESS-Keck Survey. XIV. Two Giant Exoplanets from the Distant Giants Survey. We present the Distant Giants Survey, a three-year radial velocity campaign to measure P(DG∣CS), the conditional occurrence of distant giant planets (DG; M  p  ~ 0.3-13 M J, P &gt; 1 yr) in systems hosting a close-in small planet (CS; R  p  &lt; 10 R ⊕). For the past two years, we have monitored 47 Sun-like stars hosting small transiting planets detected by TESS. We present the selection criteria used to assemble our sample and report the discovery of two distant giant planets, TOI-1669 b and TOI-1694 c. For TOI-1669 b we find that $M\sin i=0.573\pm 0.074\,\,{M}_{{\rm{J}}}$ , P = 502 ± 16 days, and e &lt; 0.27, while for TOI-1694 c, $M\sin i=1.05\pm 0.05\,\,{M}_{{\rm{J}}}$ , P = 389.2 ± 3.9 days, and e = 0.18 ± 0.05. We also confirmed the 3.8 days transiting planet TOI-1694 b by measuring a true mass of M = 26.1 ± 2.2 M ⊕. At the end of the Distant Giants Survey, we will incorporate TOI-1669 b and TOI-1694 c into our calculation of P(DG∣CS), a crucial statistic for understanding the relationship between outer giants and small inner companions.

Keywords: Radial velocity, Exoplanet detection methods, Transits, Extrasolar gaseous giant planets
A Green Bank Telescope Search for Narrowband Technosignatures between 1.1 and 1.9 GHz During 12 Kepler Planetary Transits. Agrowing avenue for determining the prevalence of life beyond Earth is to search for "technosignatures" from extraterrestrial intelligences/agents. Technosignatures require significant energy to be visible across interstellar space and thus intentional signals might be concentrated in frequency, in time, or in space, to be found in mutually obvious places. Therefore, it could be advantageous to search for technosignatures in parts of parameter space that are mutually derivable to an observer on Earth and a distant transmitter. In this work, we used the L-band (1.1-1.9 GHz) receiver on the Robert C. Byrd Green Bank Telescope to perform the first technosignature search presynchronized with exoplanet transits, covering 12 Kepler systems. We used the Breakthrough Listen turboSETI pipeline to flag narrowband hits (~3 Hz) using a maximum drift rate of ±614.4 Hz s-1 and a signal-to-noise threshold of 5-the pipeline returned ~3.4 × 105 apparently-localized features. Visual inspection by a team of citizen scientists ruled out 99.6% of them. Further analysis found two signals of interest that warrant follow up, but no technosignatures. If the signals of interest are not redetected in future work, it will imply that the 12 targets in the search are not producing transit-aligned signals from 1.1 to 1.9 GHz with transmitter powers &gt;60 times that of the former Arecibo radar. This search debuts a range of innovative technosignature techniques: citizen science vetting of potential signals of interest, a sensitivity-aware search out to extremely high drift rates, a more flexible method of analyzing on-off cadences, and an extremely low signal-to-noise threshold.

Keywords: Transits, Exoplanets, Technosignatures, Astrobiology, Search for extraterrestrial intelligence, Biosignatures, Radio astronomy
Detection of Atmospheric Escape from Four Young Mini-Neptunes. We use Keck/NIRSPEC to survey a sample of of young (&lt;1 Gyr), short-period mini-Neptunes orbiting nearby K dwarfs to measure their mass loss via the metastable helium line. We detect helium absorption from all four of the targets in our initial sample. The first detection, around TOI 560b, was announced in a previous paper. We now announce three additional detections around TOI 1430.01, 2076b, and 1683.01. All four planets show an average in-transit excess absorption of 0.7%-1.0%. However, the outflows differ in their kinematic properties. Object TOI 1430b exhibits preingress absorption, while TOI 2076b's outflow is exceptionally optically thick and shows significant postegress absorption. For all four planets, the width of the measured helium absorption signal is consistent with expectations for a photoevaporative outflow (10-30 km s-1, 5000-10,000 K). Unless broadening mechanisms other than thermal velocity and the bulk outflow velocity are significant, our observations disfavor core-powered mass-loss models, which predict much slower (1-3 km s-1) outflows. We utilize both an isothermal Parker wind model and an order-of-magnitude method to estimate the mass-loss timescale and obtain ~a few hundred megayears for each planet. We conclude that many, if not all, of these planets will lose their hydrogen-rich envelopes and become super-Earths. Our results demonstrate that most mini-Neptunes orbiting Sun-like stars have primordial atmospheres, and that photoevaporation is an efficient mechanism for stripping these atmospheres and transforming these planets into super-Earths.

Keywords: Exoplanet atmospheric composition , Mini Neptunes, Exoplanet atmospheres, Exoplanet atmospheric evolution
The Colorado Ultraviolet Transit Experiment Mission Overview. Atmospheric escape is a fundamental process that affects the structure, composition, and evolution of many planets. The signatures of escape are detectable on close-in, gaseous exoplanets orbiting bright stars, owing to the high levels of extreme-ultraviolet irradiation from their parent stars. The Colorado Ultraviolet Transit Experiment (CUTE) is a CubeSat mission designed to take advantage of the near-ultraviolet stellar brightness distribution to conduct a survey of the extended atmospheres of nearby close-in planets. The CUTE payload is a magnifying near-ultraviolet (2479-3306 Å) spectrograph fed by a rectangular Cassegrain telescope (206 mm × 84 mm); the spectrogram is recorded on a back-illuminated, UV-enhanced CCD. The science payload is integrated into a 6U Blue Canyon Technology XB1 bus. CUTE was launched into a polar, low-Earth orbit on 2021 September 27 and has been conducting this transit spectroscopy survey following an on-orbit commissioning period. This paper presents the mission motivation, development path, and demonstrates the potential for small satellites to conduct this type of science by presenting initial on-orbit science observations. The primary science mission is being conducted in 2022-2023, with a publicly available data archive coming online in 2023.

Keywords: Exoplanet atmospheres, Transits, Near ultraviolet astronomy
The On-orbit Performance of the Colorado Ultraviolet Transit Experiment Mission. We present the on-orbit performance of the Colorado Ultraviolet Transit Experiment (CUTE). CUTE is a 6U CubeSat that launched on 2021 September 27 and is obtaining near-ultraviolet (NUV; 2480 Å-3306 Å) transit spectroscopy of short-period exoplanets. The instrument comprises a 20 cm × 8 cm rectangular Cassegrain telescope, an NUV spectrograph with a holographically ruled aberration-correcting diffraction grating, and an NUV-optimized CCD detector. The telescope feeds the spectrograph through an 18' × 60″ slit. The detector is a passively cooled, back-illuminated NUV-enhanced CCD. The spacecraft bus is a Blue Canyon Technologies XB1, which has demonstrated ≤ 6″ jitter in 56% of CUTE science exposures. Following spacecraft commissioning, an on-orbit calibration program was executed to characterize the CUTE instrument's on-orbit performance. The results of this calibration indicate that the effective area of CUTE is ≈19.0-27.5 cm2 and that the average intrinsic resolution element is 2.9 Å across the bandpass. This paper describes the measurement of the science instrument performance parameters as well as the thermal and pointing characteristics of the observatory.

Keywords: Exoplanet atmospheric composition , CCD observation, Hot Jupiters, Near ultraviolet astronomy, Ultraviolet telescopes, Transmission spectroscopy, Calibration, Spectrometers, Astronomical instrumentation, Space telescopes, Exoplanet atmospheres
The Orbital Architecture of Qatar-6: A Fully Aligned Three-body System?. The evolutionary history of an extrasolar system is, in part, fossilized through its planets' orbital orientations relative to the host star's spin axis. However, spin-orbit constraints for warm Jupiters-particularly in binary star systems, which are amenable to a wide range of dynamical processes-are relatively scarce. We report a measurement of the Rossiter-McLaughlin effect, observed with the Keck/HIRES spectrograph, across the transit of Qatar-6 A b-a warm Jupiter orbiting one star within a binary system. From this measurement, we obtain a sky-projected spin-orbit angle λ = 0.°1 ± 2.°6. Combining this new constraint with the stellar rotational velocity of Qatar-6 A that we measure from TESS photometry, we derive a true obliquity $\psi ={21.82}_{-18.36}^{+8.86\circ} $ -consistent with near-exact alignment. We also leverage astrometric data from Gaia DR3 to show that the Qatar-6 binary star system is edge-on ( ${i}_{B}={90.17}_{-1.06}^{+1.07\circ} $ ), such that the stellar binary and the transiting exoplanet orbit exhibit line-of-sight orbit-orbit alignment. Ultimately, we demonstrate that all current constraints for the three-body Qatar-6 system are consistent with both spin-orbit and orbit-orbit alignment. High-precision measurements of the projected stellar spin rate of the host star and the sky-plane geometry of the transit relative to the binary plane are required to conclusively verify the full 3D configuration of the system.

Keywords: Exoplanet dynamics, Planetary theory, Exoplanet migration, Exoplanets, Planetary alignment, Hot Jupiters, Exoplanet astronomy, Exoplanet evolution, Exoplanet tides, Star-planet interactions