Sazuna/UAT_keywords huggingface dataset:
Overview of the Fiber System for the Dark Energy Spectroscopic Instrument. The Dark Energy Spectroscopic Instrument (DESI) is a revolutionary instrument designed for precise measurements of cosmic distances and the investigation of dark energy. DESI utilizes 5000 optical fibers to simultaneously measure the spectra of distant objects and aims to measure 40 million galaxies and quasars in a 5 yr survey. One of the critical challenges to DESI's success was ensuring that the fiber system was not only highly efficient but also delivered a highly stable beam enabling more reliable sky subtraction for measurements of faint objects. We achieved this stability by minimizing the stress on the fiber system during the manufacture and operation of the telescope and fiber positioning robots. We installed the DESI fiber system on the 4 m Mayall telescope with ≥99% of fibers intact, and the instrument has delivered superb optical performance throughout the initial years of the DESI survey, including ≥90% average throughput when injected with a focal ratio of ∼f/3.9 as delivered by the primary focus corrector, excluding fiber absorption losses. The design of DESI required multiple innovations to achieve these requirements, such as cleaved fibers bonded with a UV-curing epoxy to glass ferrules in the focal plane and fusion splicing instead of physical connectors. In this paper, we describe the development, delivery, and installation of the fiber system, the innovations that made the state-of-the-art performance possible, and the key lessons learned that could benefit future projects.

Keywords: Cosmological evolution, Galaxy spectroscopy, Astronomical instrumentation
The ESO SupJup Survey. III. Confirmation of <SUP>13</SUP>CO in YSES 1 b and Atmospheric Detection of YSES 1 c with CRIRES<SUP>+</SUP>. High-resolution spectroscopic characterization of young super-Jovian planets enables precise constraints on elemental and isotopic abundances of their atmospheres. As part of the ESO SupJup Survey, we present high-resolution spectral observations of two wide-orbit super-Jupiters in YSES 1 (or TYC 8998-760-1) using the upgraded VLT/CRIRES+ ( ) in K-band. We carry out free atmospheric retrieval analyses to constrain chemical and isotopic abundances, temperature structures, rotation velocities ( ), and radial velocities. We confirm the previous detection of 13CO in YSES 1 b at a higher significance of 12.6σ, but point to a higher 12CO/13CO ratio of 88 ± 13 (1σ confidence interval), consistent with the primary's isotope ratio 66 ± 5. We retrieve a solar-like composition in YSES 1 b with a C/O = 0.57 ± 0.01, indicating a formation via gravitational instability or core accretion beyond the CO iceline. Additionally, the observations lead to detections of H2O and CO in the outer planet YSES 1 c at 7.3σ and 5.7σ, respectively. We constrain the atmospheric C/O ratio of YSES 1 c to be either solar or subsolar (C/O = 0.36 ± 0.15), indicating the accretion of oxygen-rich solids. The two companions have distinct  , 5.34 ± 0.14 km s−1 for YSES 1 b and 11.3 ± 2.1 km s−1 for YSES 1 c, despite their similar natal environments. This may indicate different spin axis inclinations or effective magnetic braking by the long-lived circumplanetary disk around YSES 1 b. YSES 1 represents an intriguing system for comparative studies of super-Jovian companions and linking present atmospheres to formation histories.

Keywords: High resolution spectroscopy, Substellar companion stars, Exoplanet atmospheres
Lunar Farside Samples Returned by Chang'E-6 Mission: Significance for Understanding the South Pole-Aitken Basin Stratigraphic History. The Chang'E-6 (CE-6) mission, launched by China on 2024 May 3, marks the first successful retrieval of samples from the farside of the Moon, specifically from the southern mare plain of the Apollo basin within the South Pole-Aitken (SPA) Basin. This study aims to provide a comprehensive geological analysis of the Apollo basin, focusing on the Apollo basin materials that CE-6 may have collected. By examining the regional geology, surface mineralogy, thorium (Th) abundance, and crustal thickness, we seek to understand the implications of these materials for the SPA basin's structure and stratigraphic history. We find that the Apollo basin exhibits significant lateral compositional variations, with Mg-rich noritic materials predominantly in the southwestern portion and more feldspathic materials in the northeast, probably due to the fact that the Apollo basin is situated on different structures of the underlying SPA basin. Those Mg-rich materials, likely representing deep lithologies from local lower crust, are associated with low Th abundance, suggesting a KREEP-poor origin. The inclusion of foreign materials in the CE-6 samples increases the complexity while also enhancing their research potential. In addition to the local mare basalts, Mg-rich noritic materials associated with the Apollo basin and Th-rich materials originating from the SPA basin may also have been collected by CE-6. Laboratory research of these diverse lithologies will contribute to unraveling the characteristics of the farside mantle, the geological history of the giant SPA basin, as well as the cause of the substantial asymmetry between the lunar nearside and farside.

Keywords: Lunar craters, Lunar composition, Lunar interior, The Moon, Lunar mineralogy
Modeling Spitzer 3.6 and 4.5 μm Eclipse Depths for the Inflated Hot Jupiter in the Evolved Binary System HD 202772. As an inflated hot Jupiter orbiting an early-type primary star in the evolved binary HD 202772 system, HD 202772 A b's presence invites a study of how such a planet forms and evolves. As a prelude to potential atmospheric characterization with the latest generation of observatories, we present a reduction and analysis of eclipse light-curve observations of HD 202772 A b acquired with the Spitzer Space Telescope using the 3.6 and 4.5 μm channels. We find eclipse depths of 680 ± 68 and   ppm, respectively, corresponding to dayside effective temperatures of   and   K. The corresponding Bond albedos are consistent with the distribution of albedos for hot Jupiters observed with both Spitzer and Transiting Exoplanet Survey Satellite. The heat redistribution efficiencies consistent with the Bond albedo range predicted by one-dimensional atmospheric models in radiative-convective equilibrium are 0.71 ± 0.10 and  , respectively, indicating a weak day–night contrast for the former and a strong contrast for the latter. Given this, and the unique environment in which this planet resides, we recommend follow-up observations with JWST to more precisely constrain its atmospheric composition and structure, as well as its host stellar environment, to elucidate if and how the atmospheres of these close-in giants evolve with host stars in binaries past the main sequence.

Keywords: Hot Jupiters, Exoplanets, Infrared photometry, Planetary atmospheres, Exoplanet systems, Exoplanet astronomy, Extrasolar gaseous giant planets, Exoplanet atmospheres
Discovery of a Bow-shock Nebula Around the Z Cam-type Cataclysmic Variable SY Cancri. We report the serendipitous discovery of a bow-shock nebula around the cataclysmic variable (CV) SY Cancri. In addition, SY Cnc lies near the edge of a faint Hα-emitting nebula with a diameter of about  . The orientation of the bow shock is consistent with the direction of SY Cnc's proper motion. Nebulae are extremely rare around CVs, apart from those known to have undergone classical-nova (CN) outbursts; bow shocks and off-center nebulae are even more unusual. Nevertheless, the properties of SY Cnc and its nebulosity are strikingly similar to those of V341 Ara, another CV that is also associated with a bow shock and is likewise off-center with respect to its faint Hα nebula. Both stars are binaries with optically thick accretion disks, belonging to the classes of Z Cam CVs or nova-like variables. We discuss three scenarios to explain their properties. They may have resulted from chance encounters with interstellar gas clouds, with the stars leaving in their wakes material that is recombining after being photoionized by ultraviolet radiation from the CVs. Alternatively, the large nebulae could be ejecta from unobserved CN outbursts in the recent past, which have been decelerated through collisions with the interstellar medium (ISM), while the stars continue to snowplow through the gas. Or the faint Hα nebulae may be ambient ISM that was flash-ionized by a CN outburst in the past and is now recombining.

Keywords: Dwarf novae, Stellar bow shocks, Emission nebulae, Z Camelopardalis stars, Nova-like variable stars, Cataclysmic variable stars, Classical novae
Oxygen Abundance Throughout the Dwarf Starburst Galaxy IC 10. Measurements of oxygen abundance throughout galaxies provide insight to the formation histories and ongoing processes. Here we present a study of the gas-phase oxygen abundance in the H II regions and diffuse gas of the nearby starburst dwarf galaxy, IC 10. Using the Keck Cosmic Web Imager at W. M. Keck Observatory, we map the central region of IC 10 from 3500 to 5500 Å. The auroral [O III] 4363 Å line is detected with a high signal-to-noise ratio in 12 of 46 H II regions observed, allowing for direct measurement of the oxygen abundance, yielding a median and standard deviation of  . We investigate trends between these directly measured oxygen abundances and other H II region properties, finding weak negative correlations with the radius, velocity dispersion, and luminosity. We also find weak negative correlations between the oxygen abundance and the derived quantities of turbulent pressure and ionized gas mass, and a moderate correlation with the derived dynamical mass. Strong line, R 23 abundance estimates are used in the remainder of the H II regions and on a resolved spaxel-by-spaxel basis. There is a large offset between the abundances measured with R 23 and the auroral line method. We find that the R 23 method is unable to capture the large range of abundances observed via the auroral line measurements. The extent of this variation in the measured abundances further indicates a poorly mixed interstellar medium in IC 10, which is not typical of dwarf galaxies and may be partly due to the ongoing starburst, accretion of pristine gas, or a late stage merger.

Keywords: Starburst galaxies, Dwarf irregular galaxies, Compact H II region, Dwarf galaxies, Chemical abundances, Spectroscopy, H II regions
Walking the Line: Young Stars on the Boundary of the Epsilon Cha and Lower Centaurus Crux Associations. Gaia Data Release 3 (DR3) has provided the largest and most astrometrically precise catalog of nearby stars to date, allowing for a more complete membership census of nearby, young stellar moving groups. These loose associations of young (age &lt;100 Myr) stars within ∼100 pc are vital laboratories for the study of the early evolution of low-mass stars and planetary systems. We have exploited DR3 data to examine the boundary region between two of the youngest nearby moving groups, the ∼3–8 Myr-old ϵ Cha Association (ECA) and an ∼8 Myr-old subpopulation of the sprawling Lower Centaurus Crux (LCC) young star complex. Using spatiokinematic and color–magnitude criteria designed to select stars in the ECA, we identify ∼54 new young-star candidates that extend from the ECA core to the southern edge of the LCC. Included among our new candidates are six previously unidentified ultra-low-mass, mid- to late-M stars, lying near the future hydrogen-burning limit, which display significant infrared excesses. Our spatial, kinematic, and CMD analysis of these new candidates and previously established LCC and ECA members blurs the boundary between these groups and provides evidence for a wave of continuous star formation extending from north (LCC) to south (ECA). We discuss the factors which studies of nearby young moving groups must consider when constraining the ages of stars in these groups.

Keywords: Pre-main sequence stars, Young star clusters, Low mass stars, Stellar associations
Measuring Sub-Kelvin Variations in Stellar Temperature with High-resolution Spectroscopy. The detection of stellar variability often relies on the measurement of selected activity indicators, such as coronal emission lines and nonthermal emissions. On the flip side, the effective stellar temperature is normally seen as one of the key fundamental parameters (with mass and radius) to understanding the basic physical nature of a star and its relation with its environment (e.g., planetary instellation). We present a novel approach for measuring disk-averaged temperature variations to sub-Kelvin accuracy inspired by algorithms developed for precision radial velocity (pRV). This framework uses the entire content of the spectrum, not just preidentified lines, and can be applied to existing data obtained with high-resolution spectrographs. We demonstrate the framework by recovering the known rotation periods and temperature modulation of Barnard star and AU Mic in data sets obtained in the infrared with SPIRou at CHFT and at optical wavelengths on ϵ Eridani with HARPS at ESO 3.6 m telescope. We use observations of the transiting hot Jupiter HD189733b, obtained with SPIRou, to show that this method can unveil the minute temperature variation signature expected during the transit event, an effect analogous to the Rossiter─McLaughlin effect but in temperature space. This method is a powerful new tool for characterizing stellar activity, and in particular temperature and magnetic features at the surfaces of cool stars, affecting both pRV and transit spectroscopic observations. We demonstrate this method in the context of high-resolution spectroscopy but it could be used at lower resolution.

Keywords: High resolution spectroscopy, Stellar effective temperatures, Time series analysis
Starspot Coverage on Two New K-type Low-mass Eclipsing Binaries with Radius Inflation. Utilizing data from the Transiting Exoplanet Survey Satellite (TESS) and LAMOST, we present a photometric and spectroscopic investigation of two new K-type low-mass eclipsing binaries, TIC 56913729 and TIC 97729372. Our analysis yields masses and radii for TIC 56913729, M 1 = 0.7822 ± 0.0054M ⊙, R 1 = 0.7891 ± 0.0021R ⊙, and M 2 = 0.7532 ± 0.0052M ⊙, R 2 = 0.7648 ± 0.0021R ⊙. For TIC 97729372, the results are M 1 = 0.6410 ± 0.0058M ⊙, R 1 = 0.6537 ± 0.0069R ⊙ and M 2 = 0.6480 ± 0.0058M ⊙, R 2 = 0.6418 ± 0.0062R ⊙. In addition, by analyzing the out-of-eclipse starspot light variations, the lower limit of starspot coverage varies in different TESS sectors from 2% to 12%. We observed a clear radius inflation in the mass–radius diagram for both stars, when plotted against PARSEC and SPOT isochrones with 1 Gyr. Yet, this apparent discrepancy disappears when the comparison is made with either an older PARSEC isochrone (12 Gyr) or a SPOT isochrone (250 Myr) with high starspot coverage (F spot ∼ 85%), which is significantly higher than the typical starspot coverage deduced from light curves. Due to the lack of strong age constraints, we cannot firmly exclude that the observed radius inflation may be the result of a post-main-sequence evolutionary effect, although the spectral and kinematic properties of these stars are hardly compatible with 10–12 Myr old (Pop II) stars. It is more likely that the radius inflation is produced by the strong magnetic activity in these rapidly rotating stars, even if it is impossible to infer the actual total spot coverage, due to the age uncertainties.

Keywords: Eclipsing binary stars, Starspots, Low mass stars
Multisegment Overlap–Save Method for Coherent Dedispersion. Dispersion occurs due to the interstellar medium, which functions as a prism and causes different time delays in radio waves of varying frequencies. The coherent dedispersion technique is often used in pulsar and fast radio burst observations to mitigate this phenomenon. The widely recognized Overlap–Save approach enables this dedispersion algorithm to efficiently perform long linear convolution. However, with the present implementation, the necessary filter length for dedispersion can reach 100 million points or more. The corresponding fast Fourier transform (FFT) points should be larger than this value and a GPU cluster can be used to tackle this demanding process. This study presents the Multisegment Overlap–Save Method (MS-OSM) to effectively address this problem. Our algorithm divides signal bands into separate short segments based on frequency component delays during dedispersion. By using the short segments shuffling technique with the Overlap-Save structure, MS-OSM can greatly reduce the FFT and inverse FFT points required down to fewer than 65,536 points. To evaluate the performance of MS-OSM, a synthetic pulsar signal is created and verified using standard software tools like DSPSR and PRESTO. The results show that MS-OSM maintains the same resolution while reducing execution time and resource usage. The validation of MS-OSM is taken by processing real pulsar observation data.

Keywords: Computational methods, Computational astronomy, Pulsars
UVIT Study of the MAgellanic Clouds (U-SMAC). II. A Far-UV Catalog of the Small Magellanic Cloud: Morphology and Kinematics of Young Stellar Population. The Small Magellanic Cloud (SMC) is an irregular dwarf galaxy that has recently undergone an interaction with the Large Magellanic Cloud. The young massive stars in the SMC formed in the disturbed low-metallicity environment are important targets in astrophysics. We present a catalog of ∼76,800 far-ultraviolet (FUV) sources toward the SMC detected using the Ultra Violet Imaging Telescope onboard AstroSat. We created an FUV catalog with ∼62,900 probable SMC members which predominantly comprise main-sequence, giant, and subgiant stars. We selected four young populations (Young 1, Young 2, Young 3, and Blue Loop (BL) stars) identified from the Gaia optical color─magnitude diagram to study the morphology and kinematics of the young SMC using this catalog. We detect a clumpy morphology with a broken bar, a shell-like structure, and the inner SMC Wing for the four stellar populations. The eastern region and the northeastern regions are mainly populated by Young 1, 2, and 3 stars. The central region predominantly has the Young 2 and 3 populations, whereas the SW has BL stars, and Young 2 and 3 stars. The 2D kinematic study using proper motion (PM) reveals that Young 2 and 3 populations show two kinematically distinct subpopulations with low and high PM dispersion, whereas the Young 1 and BL stars show two kinematically distinct populations with low dispersion. Our analysis points to a kinematic disturbance along the R.A. direction for stars younger than ∼150 Myr located in the eastern region, with no significant disturbance along the decl.

Keywords: Ultraviolet astronomy, Galaxy photometry, Magellanic Clouds, Galaxy evolution
Extinction of Taurus, Orion, Perseus and California Molecular Clouds Based on the LAMOST, 2MASS, and Gaia Surveys. II. The Extinction Law. The extinction law from ultraviolet (UV) to infrared (IR; 0.2–24 μm) is determined by relying on the blue-edge method and color-excess ratios for some nearby molecular clouds, from the low-mass star-forming region to the massive star-forming region. The observational data are collected from nine photometric surveys, along with stellar parameters from the Apache Point Observatory Galaxy Evolution Experiment and LAMOST spectroscopic surveys. Within the uncertainties, the optical ratio of selective to total extinction ( ) does not vary substantially across the clouds, irrespective of the density, specifically  , where  . The IR extinction law is consistent with Wang &amp; Chen. The extinction law in the UV band is compromised by the shallow depth with A V ≤ 2 mag and is hard to describe by one parameter R. In addition, the extinction in the WISE/W1 band is significantly larger than in the Spitzer/IRAC1 band in the dense regions, which is attributed to the ice water absorption.

Keywords: Interstellar dust, Molecular clouds, Interstellar dust extinction, Reddening law, Extinction
The Discovery and Evolution of a Radio Continuum and Excited-OH Spectral-line Outburst in the Nearby Galaxy NGC 660. Arecibo 305 m Telescope observations between 2008 and 2018 detected a radio continuum and spectral-line outburst in the nearby galaxy, NGC 660. Excited-OH maser emission/absorption lines near 4.7 GHz, and H2CO absorption at 4.83 GHz varied on timescales of months. Simultaneously, a continuum outburst occurred in which a new compact component appeared, with a GHz-peaked spectrum and a 5 GHz flux density that rose to a peak value of about 500 mJy from 2008.0 to 2012.0. Follow-up interferometric continuum images from the Very Large Array at 10 GHz of this new continuum component determined it to be located at the nucleus of NGC 660. Subsequent High Sensitivity Array line and continuum very long baseline interferometry observations of the NGC 660 nucleus revealed a morphology that appears to be consistent with rapidly precessing, mildly relativistic jets from the central black hole. While requiring detailed modeling, this strongly suggests that the outburst is due to nuclear activity. From its timescale, the shape of the continuum light curve, and the milliarcsec radio structure, the most likely cause of the outburst is active galactic nuclei-type activity of accretion of a gas cloud onto the central black hole.

Keywords: Galaxies
New Moons of Uranus and Neptune from Ultradeep Pencil-beam Surveys. We have conducted extremely ultradeep pencil-beam observations for new satellites around both Uranus and Neptune. Tens of images on several different nights in 2021, 2022, and 2023 were obtained, shifted, and added together to reach as faint as 26.9 and 27.2 mag in the r band around Uranus and Neptune, respectively. One new moon of Uranus, S/2023 U1, and two new moons of Neptune, S/2021 N1 and S/2002 N5, were found. S/2023 U1 was 26.6 mag, is about 7 km in diameter, and has a distant, eccentric, and inclined retrograde orbit similar to Caliban and Stephano, implying these satellites are fragments from a once larger parent satellite. S/2021 N1 was 26.9 mag, about 14 km in size, and has a retrograde orbit similar to Neso and Psamathe, indicating they are a dynamical family. We find S/2021 N1 is in Kozai─Lidov orbital resonance. S/2002 N5 was 25.9 mag, is about 23 km in size, and it makes a family of distant prograde satellites with Sao and Laomedeia. This survey mostly completes the outer satellites of Uranus to about 8 km and Neptune to about 14 km in diameter. The size distributions of satellite dynamical families around the giant planets shows a strong steepening in the power-law size distribution smaller than 5 km in diameter. The satellites of a family become much more common at diameters smaller than 5 km and their size distribution is consistent with a collisional breakup of a once larger parent satellite.

Keywords: Irregular satellites, Neptunian satellites, Natural satellites (Solar system), Uranian satellites