Sazuna/UAT_keywords huggingface dataset:
Staring at the Shadows of Archaic Galaxies: Damped Lyα and Metal Absorbers Toward a Young z ∼ 6 Weak-line Quasar. We characterize the Lyα halo and absorption systems toward PSO J083+11, a unique z = 6.3401 weak-line quasar, using Gemini Near-infrared Spectrograph, Magellan Folded-port Infrared Echellette, and Very Large Telescope Multi Unit Spectroscopic Explorer (MUSE) data. Strong absorptions by hydrogen and several metal lines (e.g., C II, Mg II, and O I) are discovered in the spectrum, which indicates the presence of: (i) a proximate subdamped Lyα (sub-DLA) system at z = 6.314 and (ii) a Mg II absorber at z = 2.2305. To describe the observed damping wing signal, we model the Lyα absorption with a combination of a sub-DLA with the neutral hydrogen column density of $\mathrm{log}{N}_{\mathrm{HI}}\,=\,20.03\pm 0.30\,{\mathrm{cm}}^{-2}$ and absorption from the intergalactic medium with a neutral fraction of around 10%. The sub-DLA toward PSO J083+11 has an abundance ratio of [C/O] = -0.04 ± 0.33 and metallicity of [O/H] = -2.19 ± 0.44, similar to those of low-redshift metal-poor DLAs. These measurements suggest that the sub-DLA might truncate PSO J083+11's proximity zone size and complicate the quasar lifetime measurement. However, this quasar shows no sign of a Lyα halo in the MUSE data cube, where the estimated 1σ limit of surface brightness is $2.76\times {10}^{-18}\,\mathrm{erg}\,{{\rm{s}}}^{-1}\,{\mathrm{cm}}^{-2}\,{\mathrm{arcsec}}^{-2}$ at an aperture size of 1″, or equivalent to a Lyα luminosity of ≤43.46 erg s-1. This nondetection, while being only weak independent evidence on its own, is at least consistent with a young quasar scenario, as expected for a quasar with a short accretion timescale.

Keywords: Early universe, Supermassive black holes, Metal line absorbers, Quasar absorption line spectroscopy, Quasars, Active galaxies, Damped Lyman-alpha systems, Active galactic nuclei, Reionization, High-redshift galaxies
The Chemical Composition of Extreme-velocity Stars. Little is known about the origin of the fastest stars in the Galaxy. Our understanding of the chemical evolution history of the Milky Way and surrounding dwarf galaxies allows us to use the chemical composition of a star to investigate its origin and to say whether it was formed in situ or was accreted. However, the fastest stars, the hypervelocity stars, are young and massive and their chemical composition has not yet been analyzed. Though it is difficult to analyze the chemical composition of a massive young star, we are well versed in the analysis of late-type stars. We have used high-resolution ARCES/3.5 m Apache Point Observatory, MIKE/Magellan spectra to study the chemical details of 15 late-type hypervelocity star candidates. With Gaia EDR3 astrometry and spectroscopically determined radial velocities we found total velocities with a range of 274-520 km s-1 and mean value of 381 km s-1. Therefore, our sample stars are not fast enough to be classified as hypervelocity stars, and are what is known as extreme-velocity stars. Our sample has a wide iron abundance range of -2.5 ≤ [Fe/H] ≤ -0.9. Their chemistry indicates that at least 50% of them are accreted extragalactic stars, with iron-peak elements consistent with prior enrichment by sub-Chandrasekhar mass Type Ia supernovae. Without indication of binary companions, their chemical abundances and orbital parameters indicate that they are the accelerated tidal debris of disrupted dwarf galaxies. * This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. † This paper includes data gathered with the 3.5 m Telescope at Apache Point Observatory.

Keywords: Stellar populations, Population II stars, Hypervelocity stars, Stellar abundances
OGLE-2016-BLG-1093Lb: A Sub-Jupiter-mass Spitzer Planet Located in the Galactic Bulge. OGLE-2016-BLG-1093 is a planetary microlensing event that is part of the statistical Spitzer microlens parallax sample. The precise measurement of the microlens parallax effect for this event, combined with the measurement of finite-source effects, leads to a direct measurement of the lens masses and system distance, M host =0.38-0.57 M ⊙ and m  p  = 0.59-0.87 M Jup, and the system is located at the Galactic bulge (D  L  ~ 8.1 kpc). Because this was a high-magnification event, we are also able to empirically show that the "cheap-space parallax" concept produces well-constrained (and consistent) results for ∣π E∣. This demonstrates that this concept can be extended to many two-body lenses. Finally, we briefly explore systematics in the Spitzer light curve in this event and show that their potential impact is strongly mitigated by the color constraint.

Keywords: Gravitational microlensing exoplanet detection, Satellite microlensing parallax
Assessing the Transiting Exoplanet Survey Satellite's Yield of Rocky Planets Around Nearby M Dwarfs. Terrestrial planets are easier to detect around M dwarfs than other types of stars, making them promising for next-generation atmospheric characterization studies. The Transiting Exoplanet Survey Satellite (TESS) mission has greatly increased the number of known M-dwarf planets that we can use to perform population studies, allowing us to explore how the rocky planet occurrence rate varies with host radius, following in the footsteps of past work with Kepler data. In this paper, we use simulations to assess TESS's yield of small (0.5 R ⊕ &lt; R  p  &lt; 2 R ⊕) planet candidates around nearby (d &lt; 30 pc) M dwarfs. We highlight the underappreciated fact that, while TESS was indeed expected to find a large number of planets around M dwarfs overall, it was not expected to have a high planetary yield for the latest M dwarfs. Furthermore, we find that TESS has detected fewer planets around stars with R ⋆ &lt; 0.3 R ⊙ than even was expected (11 observed versus 24 ± 5 expected). We find evidence that the photometric noise of stars in the TESS bandpass increases with decreasing radius for M dwarfs. However, this trend cannot explain the observed distribution of planets. Our main conclusions are (1) the planet occurrence rate likely does not increase, and may decrease for the latest M dwarfs; and (2) there are at least 17, and potentially three times that number, transiting planets around nearby late-M dwarfs that still will not be detected by the end of TESS's fourth year.

Keywords: Extrasolar rocky planets, Late-type dwarf stars, Exoplanet catalogs, M dwarf stars
A New Analysis of Eight Spitzer Phase Curves and Hot Jupiter Population Trends: Qatar-1b, Qatar-2b, WASP-52b, WASP-34b, and WASP-140b. With over 30 phase curves observed during the warm Spitzer mission, the complete data set provides a wealth of information relating to trends and three-dimensional properties of hot Jupiter atmospheres. In this work we present a comparative study of seven new Spitzer phase curves for four planets with equilibrium temperatures T eq ~ 1300K: Qatar-2b, WASP-52b, WASP-34b, and WASP-140b, as well as a reanalysis of the 4.5 μm Qatar-1b phase curve due to the similar equilibrium temperature. In total, five 4.5 μm phase curves and three 3.6 μm phase curves are analyzed here with a uniform approach. Using these new results, in combination with literature values for the entire population of published Spitzer phase curves of hot Jupiters, we present evidence for a linear trend of increasing hotspot offset with increasing orbital period, as well as observational evidence for two classes of planets in apparent redistribution versus equilibrium temperature parameter space, and tentative evidence for a dependence of hotspot offset on planetary surface gravity in our ~1300 K sample. We do not find trends in apparent heat redistribution with orbital period or gravity. Nonuniformity in literature Spitzer data analysis techniques precludes a definitive determination of the sources or lack of trends.

Keywords: Exoplanet dynamics, Exoplanets, Hot Jupiters, Exoplanet astronomy, Extrasolar gaseous planets, Exoplanet atmospheres
Activity and Rotation of Nearby Field M Dwarfs in the TESS Southern Continuous Viewing Zone. The evolution of magnetism in late-type dwarfs remains murky, as we can only weakly predict levels of activity for M dwarfs of a given mass and age. We report results from our spectroscopic survey of M dwarfs in the Southern Continuous Viewing Zone (CVZ) of the Transiting Exoplanet Survey Satellite (TESS). As the TESS CVZs overlap with those of the James Webb Space Telescope, our targets constitute a legacy sample for studies of nearby M dwarfs. For 122 stars, we obtained at least one R ≍ 2000 optical spectrum with which we measure chromospheric Hα emission, a proxy for magnetic field strength. The fraction of active stars is consistent with what is expected for field M dwarfs; as in previous studies, we find that late-type M dwarfs remain active for longer than their early-type counterparts. While the TESS light curves for ≍20% of our targets show modulations consistent with rotation, TESS systematics are not well enough understood for confident measurements of rotation periods (P rot) longer than half the length of an observing sector. We report periods for 12 stars for which we measure P rot ≲ 15 days or find confirmation for the TESS-derived P rot in the literature. Our sample of 21 P rot, which includes periods from the literature, is consistent with our targets being spun-down field stars. Finally, we examine the Hα-to-bolometric luminosity distribution for our sample. Two stars are rotating fast enough to be magnetically saturated, but are not, hinting at the possibility that fast rotators may appear inactive in Hα.

Keywords: Stellar rotation, Low mass stars, Stellar activity
Comparisons of Type Ia Supernova Light Curves in the UV and Optical with the Swift Ultra-violet/Optical Telescope. We examine the light-curve parameters of 97 nearby Type Ia supernovae (SN Ia) in the ultraviolet and optical using observations from the Swift Ultra-violet/Optical Telescope. Our light-curve models used linear combinations of templates, which were based on functional principal component analysis of the optical photometry of SN Ia. The weights for each principal component used in the fit capture certain aspects of the light-curve properties. We find that there is little difference in the overall variability of principal component scores across filters. We also find correlations between certain filters and PC components, indicating that the UV and optical properties seem to be tied together. This is a promising step in UV SN Ia analysis and suggests that UV light curves may be used to infer optical properties, paving the way for future cosmological studies.

Keywords: Ultraviolet astronomy, Type Ia supernovae, Optical astronomy, Ultraviolet photometry
Multiresolution HEALPix Maps for Multiwavelength and Multimessenger Astronomy. HEALPix-the Hierarchical Equal Area isoLatitude Pixelization-has become a standard in high-energy and gravitational wave astronomy. Originally developed to improve the efficiency of all-sky Fourier analyses, it is now also utilized to share sky localization information. When used for this purpose the need for a homogeneous all-sky grid represents a limitation that hinders a broader community adoption. This work presents mhealpy, a Python library able to create, handle and analyze multiresolution maps, a solution to this problem. It supports efficient pixel querying, arithmetic operations between maps, adaptive mesh refinement, plotting, and serialization into FITS-Flexible Image Transport System-files. This HEALPix extension makes it suitable to represent highly resolved region, resulting in a convenient common format to share spatial information for joint multiwavelength and multimessenger analyses.

Keywords: Open source software, Astronomy software
Into the Depths: A New Activity Metric for High-precision Radial Velocity Measurements Based on Line Depth Variations. The discovery and characterization of extrasolar planets using radial velocity (RV) measurements is limited by noise sources from the surfaces of host stars. Current techniques to suppress stellar magnetic activity rely on decorrelation using an activity indicator (e.g., strength of the Ca II lines, width of the cross-correlation function, broadband photometry) or measurement of the RVs using only a subset of spectral lines that have been shown to be insensitive to activity. Here, we combine the above techniques by constructing a high-signal-to-noise activity indicator, the depth metric ${ \mathcal D }(t)$ , from the most activity-sensitive spectral lines using the "line-by-line" method of Dumusque (2018). Analogous to photometric decorrelation of RVs or Gaussian progress regression modeling of activity indices, time series modeling of ${ \mathcal D }(t)$ reduces the amplitude of magnetic activity in RV measurements; in an αCenB RV time series from HARPS, the RV rms was reduced from 2.67 to 1.02 m s-1. ${ \mathcal D }(t)$ modeling enabled us to characterize injected planetary signals as small as 1 m s-1. In terms of noise reduction and injected signal recovery, ${ \mathcal D }(t)$ modeling outperforms activity mitigation via the selection of activity-insensitive spectral lines. For Sun-like stars with activity signals on the m s-1 level, the depth metric independently tracks rotationally modulated and multiyear stellar activity with a level of quality similar to that of the FWHM of the CCF and log ${R}_{\mathrm{HK}}^{{\prime} }$ . The depth metric and its elaborations will be a powerful tool in the mitigation of stellar magnetic activity, particularly as a means of connecting stellar activity to physical processes within host stars.

Keywords: Exoplanet detection methods, Radial velocity
Confirmation of Water Absorption in the Thermal Emission Spectrum of the Hot Jupiter WASP-77Ab with HST/WFC3. Secondary eclipse observations of hot Jupiters can reveal both their compositions and thermal structures. Previous observations have shown a diversity of hot Jupiter eclipse spectra, including absorption features, emission features, and featureless blackbody-like spectra. We present a secondary eclipse spectrum of the hot Jupiter WASP-77Ab observed between 1 and 5 μm with the Hubble Space Telescope (HST) and the Spitzer Space Telescope. The HST observations show signs of water absorption indicative of a noninverted thermal structure. We fit the data with both a one-dimensional free retrieval and a grid of one-dimensional self-consistent forward models to confirm this noninverted structure. The free retrieval places a 3σ lower limit on the atmospheric water abundance of $\mathrm{log}({n}_{{{\rm{H}}}_{2}{\rm{O}}})\gt -4.78$ and cannot constrain the CO abundance. The grid fit produces a slightly superstellar metallicity and constrains the carbon-to-oxygen ratio to less than or equal to the solar value. We also compare our data to recent high-resolution observations of WASP-77Ab taken with the IGRINS/IGRINS spectrograph. We find that the best-fit model to the IGRINS data gives a reduced chi squared of χ2 ν = 1.32 when compared to the WFC3 data. However, the metallicity derived from the IGRINS data is significantly lower than that derived from our self-consistent model fit. We find that this difference may be due to disequilibrium chemistry, and the varying results between the models applied here demonstrate the model dependence of derived metallicities when comparing to low-resolution, low-wavelength coverage data alone. Future work to combine observations from IGRINS, HST, and the James Webb Space Telescope will improve our estimate of the atmospheric composition of WASP-77Ab.

Keywords: Exoplanet atmospheric composition , Extrasolar gaseous giant planets, Hot Jupiters
Near-infrared Spectra of the Inflated Post-common Envelope Brown Dwarf NLTT 5306 B. NLTT 5306 is a post-common envelope binary made up of a white dwarf host and brown dwarf companion that has shown evidence of inflation and active mass donation despite not filling its Roche lobe. Two proposed mechanisms for the brown dwarf's inflation are magnetic interactions and a high-metallicity, cloudy atmosphere. We present moderate-resolution (R ≲ 2000) J-band Keck/NIRSPEC observations of this system. These phase-resolved data allow us to constrain differences between atmospheric parameters of the day- and nightside of the brown dwarf. Our day- and nightside effective temperature measurements are consistent, in agreement with the brightness temperatures measurements from Casewell et al. The dayside favors a slightly lower surface gravity, perhaps stemming from the material streaming between the two objects. Finally, our data show a preference for low-metallicity models. This would be expected from the system's old age, but provides direct evidence that a high-metallicity, cloudy brown dwarf atmosphere is not responsible for the witnessed inflation. These results strengthen the case for magnetic interactions leading to inflation of NLTT 5306 B.

Keywords: Brown dwarfs, Roche lobe, White dwarf stars, Spectroscopy, Common envelope evolution
A Zwicky Transient Facility Look at Optical Variability of Young Stellar Objects in the North America and Pelican Nebulae Complex. We present a study of 323 photometrically variable young stellar objects that are likely members of the North America and Pelican nebulae star-forming region. To do so, we utilize over two years of data in the g and r photometric bands from the Zwicky Transient Facility. We first investigate periodic variability, finding 46 objects (~15% of the sample) with significant periods that phase well and can be attributed to stellar rotation. We then use the quasiperiodicity (Q) and flux asymmetry (M) variability metrics to assign morphological classifications to the remaining aperiodic light curves. Another ~39% of the variable star sample beyond the periodic (low Q) sources are also flux-symmetric, but with a quasiperiodic (moderate Q) or stochastic (high Q) nature. Concerning flux-asymmetric sources, our analysis reveals ~14% bursters (high negative M) and ~29% dippers (high positive M). We also investigate the relationship between variability slopes in the g versus g - r color-magnitude diagram, and the light-curve morphological classes. Burster-type objects have shallow slopes, while dipper-type variables tend to have higher slopes that are consistent with extinction-driven variability. Our work is one of the earliest applications of the Q and M metrics to ground-based data. We therefore contrast the Q values of high-cadence and high-precision space-based data, for which these metrics were designed, with Q determinations resulting from degraded space-based light curves that have the cadence and photometric precision characteristic of ground-based data.

Keywords: Young star clusters, T Tauri stars, Pre-main sequence stars, Time domain astronomy, Slow irregular variable stars, Stellar rotation
The Hosts of X-Ray Absorption Lines Toward AGNs. Most baryonic matter in the universe exists in gaseous form and can be found in structures such as galactic halos and the low-density intergalactic medium. Proposed X-ray spectroscopy missions such as Athena, Arcus, and Lynx will have the capability to identify absorption lines in spectra toward bright active galactic nuclei (AGNs), which can be used as tools to probe this missing matter. In this study, we examine the optical fields surrounding 15 primary observing targets and identify the foreground galaxies and galaxy groups that are potential hosts of absorption. We record the basic properties of the potential host and their angular and physical separation from the AGN line of sight. This process is done by marking the location of various galaxies and groups in optical images of the field surrounding the target and plotting their angular separation versus redshift to gauge the physical proximity to the background source. We identify the surrounding objects according to those with measured redshifts and those that require accurate redshift measurements.

Keywords: Hot intergalactic medium, Intergalactic gas, Intergalactic medium phases
The Long-term Spectroscopic and Photometric Behavior of the Carbon Star RS Cygni. RS Cygni is a semiregular variable carbon star that has a distinctive light curve. Twenty-one years of optical spectroscopic and photometric observations of this star made at Grinnell College have been used not only to produce a comprehensive survey of the behavior of this star but also to compare these two sets of data. A number of spectral features vary in strength with the cycle of the star and some, but not all, of this variation is correlated with the dips that often occur near the maxima of the light curve. In particular, the strengths of the Balmer emission lines often have two peaks per cycle. Such correlation might be consistent with a mechanism for producing the dips, such as dust formation, that reduces the brightness in a way that does not involve rapid changes in photospheric characteristics. The large amount of data and the precision of the photometry presented give an unusually detailed view of how the light of RS Cyg varies over time.

Keywords: BV photometry, Carbon stars, Semi-regular variable stars, Spectroscopy, Circumstellar dust
A Gaia View on the Star Formation in the Monoceros OB1 and R1 Associations. Stellar kinematics provides the key to understanding the star formation process. In this respect, we present a kinematic study of the Monoceros OB1 (Mon OB1) and R1 (Mon R1) associations using the recent Gaia data and radial velocities of stars derived from high-resolution spectroscopy and the literature. A total of 728 members are selected using the criteria based on the intrinsic properties of young stars, parallaxes, and proper motions. The spatial distribution and kinematic properties of members show that these associations have distinct substructures. In Mon OB1, we find one northern group and two southern groups. Mon R1 is composed of three small stellar groups that are spatially and kinematically distinct. Some stars are found in a halo around these two associations. We detect patterns of expansion for most stellar groups in the associations. In addition, two stellar groups in Mon OB1 show the signature of rotation, which provides an important constraint on cluster formation. The star formation history of Mon OB1 is slightly revised. Star formation first occurred in the southern region and subsequently in the northern region. Recent star-forming events ignited deeper into the southern region, while some stars are escaping from Mon OB1, forming a halo. Mon R1 might have formed at the same epoch as the formation of the northern group in Mon OB1. Given that star formation is taking place on different scales along a large arc-like structure, Mon OB1 and Mon R1 may be the results of hierarchical star formation.

Keywords: Stellar kinematics, Stellar dynamics, Star formation, Open star clusters, Stellar associations