Sazuna/UAT_keywords huggingface dataset:
Search for TiO and Optical Nightside Emission from the Exoplanet WASP-33b. With a temperature akin to an M dwarf, WASP-33b is among the hottest Jupiters known, making it an ideal target for high-resolution optical spectroscopy. By analyzing both transmission and emission spectra, we aim to substantiate previous reports of atmospheric TiO and a thermal inversion within the planet's atmosphere. We observed two transits and six arcs of the phase curve with the Echelle SpectroPolarimetric Device for the Observation of Stars (ESPaDOnS) on the Canada-France-Hawaii Telescope and High Resolution Echelle Spectrometer (HIRES) on the Keck telescope, which provide high spectral resolution and ample wavelength coverage. We employ the Doppler cross-correlation technique to search for the molecular signatures of TiO and H2O in these spectra, using models based on the TiO line list of Plez. Though we cannot exclude line-list-dependent effects, our data do not corroborate previous indications of a thermal inversion. Instead we place a 3σ upper limit of 10-9 on the volume mixing ratio of TiO for the T-P profile we consider. While we are unable to constrain the volume mixing ratio of water, our strongest constraint on TiO comes from dayside emission spectra. This apparent absence of a stratosphere sits in stark contrast to previous observations of WASP-33b as well as theoretical predictions for the atmospheres of highly irradiated planets. The discrepancy could be due to variances between line lists, and we stress that detection limits are only as good as the line list employed, and are only valid for the specific T-P profile considered due to the strong degeneracy between lapse rate ( ${dT}/d\mathrm{log}P$ ) and molecular abundance.

Keywords: High resolution spectroscopy, Exoplanet atmospheric composition , Hot Jupiters, Exoplanets, Astronomy data analysis, Transmission spectroscopy, Extrasolar gaseous giant planets, Exoplanet atmospheres
Scaling K2. III. Comparable Planet Occurrence in the FGK Samples of Campaign 5 and Kepler. Using our K2 Campaign 5 fully automated planet-detection data set (43 planets), which has corresponding measures of completeness and reliability, we infer an underlying planet population model for the FGK dwarf sample (9257 stars). Implementing a broken power law for both the period and radius distributions, we find an overall planet occurrence of ${1.00}_{-0.51}^{+1.07}$ planets per star within a period range of 0.5-38 days. Making similar cuts and running a comparable analysis on the Kepler sample (2318 planets; 94,222 stars), we find an overall occurrence of 1.10 ± 0.05 planets per star. Since the Campaign 5 field is nearly 120 angular degrees away from the Kepler field, this occurrence similarity offers evidence that the Kepler sample may provide a good baseline for Galactic inferences. Furthermore, the Kepler stellar sample is metal-rich compared to the K2 Campaign 5 sample, so a finding of occurrence parity may reduce the role of metallicity in planet formation. However, a weak (1.5σ) difference, in agreement with metal-driven formation, is found when assuming the Kepler model power laws for the K2 Campaign 5 sample and optimizing only the planet occurrence factor. This weak trend indicates that further investigation of metallicity-dependent occurrence is warranted once a larger sample of uniformly vetted K2 planet candidates is made available.

Keywords: Exoplanet catalogs, Dwarf stars
The Structure of Stellar Disks in Isolated Lenticular Galaxies. We have obtained imaging data in two photometric bands, g and r, for a sample of 42 isolated lenticular galaxies with the Las Cumbres Observatory 1 m telescope network. We have analyzed the structure of their large-scale stellar disks. The parameters of surface-brightness distributions have been determined including the radial profile shapes and disk thicknesses. After inspecting the radial brightness profiles, all of the galaxies have been classified into pure exponential (Type I), truncated (Type II), and antitruncated (Type III) disks. By comparing the derived statistics of the radial profile shapes with our previous sample of cluster S0s, we noted a prominent difference between stellar disks of S0s galaxies in quite rarefied environments and in clusters: it is only in sparse environments that Type II disks, with profile truncations, can be found. This finding implies probable different dynamical history of S0 galaxies in different environments. ∗ Based on observations made with the Las Cumbres Observatory telescope network.

Keywords: Lenticular galaxies, Disk galaxies
TESS Reveals a Short-period Sub-Neptune Sibling (HD 86226c) to a Known Long-period Giant Planet. The Transiting Exoplanet Survey Satellite mission was designed to find transiting planets around bright, nearby stars. Here, we present the detection and mass measurement of a small, short-period (≈4 days) transiting planet around the bright (V = 7.9), solar-type star HD 86226 (TOI-652, TIC 22221375), previously known to host a long-period (∼1600 days) giant planet. HD 86226c (TOI-652.01) has a radius of 2.16 ± 0.08 R⊕ and a mass of ${7.25}_{-1.12}^{+1.19}$ M⊕, based on archival and new radial velocity data. We also update the parameters of the longer-period, not-known-to-transit planet, and find it to be less eccentric and less massive than previously reported. The density of the transiting planet is 3.97 g cm-3, which is low enough to suggest that the planet has at least a small volatile envelope, but the mass fractions of rock, iron, and water are not well-constrained. Given the host star brightness, planet period, and location of the planet near both the "radius gap" and the "hot Neptune desert," HD 86226c is an interesting candidate for transmission spectroscopy to further refine its composition. * This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Keywords: Exoplanet astronomy, Exoplanet systems
An Astrometric Planetary Companion Candidate to the M9 Dwarf TVLM 513-46546. Astrometric observations of the M9 dwarf TVLM 513-46546 taken with the VLBA reveal an astrometric signature consistent with a period of 221 ± 5 days. The orbital fit implies that the companion has a mass mp = 0.35-0.42 MJ, a circular orbit (e ≃ 0), a semimajor axis a = 0.28-0.31 au, and an inclination angle i = 71°-88°. The detected companion, TVLM 513b, is one of the few giant-mass planets found associated with ultracool dwarfs. The presence of a Saturn-like planet on a circular orbit 0.3 au from a 0.06-0.08 M⊙ star represents a challenge to planet formation theory. This is the first astrometric detection of a planet at radio wavelengths.

Keywords: Extrasolar gaseous giant planets, Exoplanets
Dynamical Instabilities in Systems of Multiple Short-period Planets Are Likely Driven by Secular Chaos: A Case Study of Kepler-102. We investigated the dynamical stability of high-multiplicity Kepler and K2 planetary systems. Our numerical simulations find instabilities in ∼20% of the cases on a wide range of timescales (up to 5 × 109 orbits) and over an unexpectedly wide range of initial dynamical spacings. To identify the triggers of long-term instability in multiplanet systems, we investigated in detail the five-planet Kepler-102 system. Despite having several near-resonant period ratios, we find that mean-motion resonances are unlikely to directly cause instability for plausible planet masses in this system. Instead, we find strong evidence that slow inward transfer of angular momentum deficit (AMD) via secular chaos excites the eccentricity of the innermost planet, Kepler-102 b, eventually leading to planet-planet collisions in ∼80% of Kepler-102 simulations. Kepler-102 b likely needs a mass ≳0.1 M⊕, hence a bulk density exceeding about half Earth's, in order to avoid dynamical instability. To investigate the role of secular chaos in our wider set of simulations, we characterize each planetary system's AMD evolution with a "spectral fraction" calculated from the power spectrum of short integrations (∼5 × 106 orbits). We find that small spectral fractions (≲0.01) are strongly associated with dynamical stability on long timescales (5 × 109 orbits) and that the median time to instability decreases with increasing spectral fraction. Our results support the hypothesis that secular chaos is the driver of instabilities in many nonresonant multiplanet systems and also demonstrate that the spectral analysis method is an efficient numerical tool to diagnose long-term (in)stability of multiplanet systems from short simulations.

Keywords: Exoplanet dynamics, Exoplanet systems, Exoplanets, Orbital evolution
Random Forests Applied to High-precision Photometry Analysis with Spitzer IRAC. We present a new method employing machine-learning techniques for measuring astrophysical features by correcting systematics in IRAC high-precision photometry using random forests. The main systematic in IRAC light-curve data is position changes due to unavoidable telescope motions coupled with an intrapixel response function. We aim to use the large amount of publicly available calibration data for the single pixel used for this type of work (the sweet-spot pixel) to make a fast, easy-to-use, accurate correction to science data. This correction on calibration data has the advantage of using an independent data set instead of the science data themselves, which has the disadvantage of including astrophysical variations. After focusing on feature engineering and hyperparameter optimization, we show that a boosted random forest model can reduce the data such that we measure the median of 10 archival eclipse observations of XO-3b to be 1459 ± 200 ppm. This is a comparable depth to the average of those in the literature done by seven different methods; however, the spread in measurements is 30%-100% larger than those literature values, depending on the reduction method. We also caution others attempting similar methods to check their results with the fiducial data set of XO-3b, as we were also able to find models providing initially great scores on their internal test data sets but whose results significantly underestimated the eclipse depth of that planet.

Keywords: Astronomy software, Exoplanets, Infrared astronomy, Infrared telescopes, Space telescopes, Random Forests, Astronomy data reduction
The Hubble Space Telescope's Near-UV and Optical Transmission Spectrum of Earth as an Exoplanet. We observed the 2019 January total lunar eclipse with the Hubble Space Telescope's STIS spectrograph to obtain the first near-UV (1700-3200 Å) observation of Earth as a transiting exoplanet. The observatories and instruments that will be able to perform transmission spectroscopy of exo-Earths are beginning to be planned, and characterizing the transmission spectrum of Earth is vital to ensuring that key spectral features (e.g., ozone, or O3) are appropriately captured in mission concept studies. O3 is photochemically produced from O2, a product of the dominant metabolism on Earth today, and it will be sought in future observations as critical evidence for life on exoplanets. Ground-based observations of lunar eclipses have provided the Earth's transmission spectrum at optical and near-IR wavelengths, but the strongest O3 signatures are in the near-UV. We describe the observations and methods used to extract a transmission spectrum from Hubble lunar eclipse spectra, and identify spectral features of O3 and Rayleigh scattering in the 3000-5500 Šregion in Earth's transmission spectrum by comparing to Earth models that include refraction effects in the terrestrial atmosphere during a lunar eclipse. Our near-UV spectra are featureless, a consequence of missing the narrow time span during the eclipse when near-UV sunlight is not completely attenuated through Earth's atmosphere due to extremely strong O3 absorption and when sunlight is transmitted to the lunar surface at altitudes where it passes through the O3 layer rather than above it.

Keywords: Lunar eclipses, Earth atmosphere, The Moon, Earth (planet), Exoplanet atmospheres
Characterization of the Atmosphere of Super-Earth 55 Cancri e Using High-resolution Ground-based Spectroscopy. The nearby super-Earth 55 Cnc e orbits a bright (V = 5.95 mag) star with a period of ∼18 hr and a mass of ∼8M⊕. Its atmosphere may be water-rich and have a large-scale height; though, attempts to characterize it have yielded ambiguous results. Here we present a sensitive search for water and TiO in its atmosphere at high spectral resolution using the Gemini North telescope and the GRACES spectrograph. We combine observations with previous observations from Subaru and CFHT, improving the constraints on the presence of water vapor. We adopt parametric models with an updated planet radius based on recent measurements, and use a cross-correlation technique to maximize sensitivity. Our results are consistent with atmospheres that are cloudy or contain minimal amounts of water and TiO. Using these parametric models, we rule out a water-rich atmosphere (VMR $\geqslant $ 0.1%) with a mean molecular weight of $\leqslant $ 15 g mol-1 at a 3σ confidence level, improving on the previous limit by a significant margin. For TiO, we rule out a mean molecular weight of $\leqslant $ 5 g mol-1 with a 3σ confidence level for a VMR greater than 10-8; for a VMR of greater than 10-7, the limit rises to a mean molecular weight of $\leqslant $ 10 g mol-1. We can rule out low mean-molecular-weight chemical equilibrium models both including and excluding TiO/VO at very high confidence levels (&gt;10σ). Overall, our results are consistent with an atmosphere with a high mean molecular weight and/or clouds, or no atmosphere.

Keywords: High resolution spectroscopy, Exoplanet atmospheric composition , Transits, Optical astronomy, Super Earths, Ground-based astronomy
Fine Structures in the Main Sequence Revealed by Gaia Data Release 2. The Hertzsprung-Russell diagram (HRD) is fully examined using the Fourier analysis. This work shows more stars are above the gap in the lower main sequence than below it, and this implies that stars spend more time above the gap while they undergo variability associated with the 3He instability. The enhanced HRD also shows the width of the gap is not linear and depends on the ${G}_{\mathrm{BP}}-{G}_{\mathrm{RP}}$ color up until ${G}_{\mathrm{BP}}-{G}_{\mathrm{RP}}=2.7$ . Beyond this color limit, the gap is hardly seen. Besides, a new low density region is revealed for the first time centered at MG ≈ 10.7 and GBP - GRP ≈ 2.8, which is below the lower right corner of the gap. This work also shows that the main sequence appears to have fine stripes where stellar densities are relatively low or high compared to their adjacent regions on the main sequence. These stripes can be seen throughout the main sequence of stars redder than GBP - GRP = 0.8 and are not limited to any specific color or spectral type. Slopes of these features are different from the main sequence, but are pretty consistent throughout the main sequence, with a few exceptions. We are perplexed by these new features, but the complexities of stellar atmospheric features and opacities of dwarfs may have caused these patterns.

Keywords: Main sequence stars, Hertzsprung Russell diagram, Parallax
A Multiwavelength Study of the Cool Core Cluster MACS J1447.4+0827. Clusters of galaxies are outstanding laboratories for understanding the physics of supermassive black hole (SMBH) feedback. Here we present the first Chandra, Karl G. Jansky Very Large Array, and Hubble Space Telescope analysis of MACS J1447.4+0827 (z = 0.3755), one of the strongest cool core clusters known, in which extreme feedback from its central SMBH is needed to prevent the hot intracluster gas from cooling. Using this multiwavelength approach, including 70 ks of Chandra X-ray observations, we detect the presence of collimated jetted outflows that coincide with a southern and a northern X-ray cavity. The total mechanical power associated with these outflows (Pcav ≈ 6 × 1044 erg s-1) is roughly consistent with the energy required to prevent catastrophic cooling of the hot intracluster gas (Lcool = 1.71 ± 0.01 × 1045 erg s-1 for tcool = 7.7 Gyr), implying that powerful SMBH feedback was in place several Gyr ago in MACS J1447.7+0827. In addition, we detect the presence of a radio minihalo that extends over 300 kpc in diameter (P1.4GHz = 3.0 ± 0.3 × 1024 W Hz-1). The X-ray observations also reveal an ∼20 kpc plumelike structure that coincides with optical dusty filaments that surround the central galaxy. Overall, this study demonstrates that the various physical phenomena occurring in the most nearby clusters of galaxies are also occurring in their more distant analogs.

Keywords: Galaxy clusters, Black hole physics, X-ray astronomy, Radio jets, High energy astrophysics, Hubble Space Telescope, Relativistic jets, Active galactic nuclei, Optical observatories
Time-sequence Spectroscopy of Epsilon CrA: The 518 nm Mg I Triplet Region Analyzed with Broadening Functions. High-resolution spectroscopic observations of the W UMa-type binary ɛ CrA obtained as a time-monitoring sequence on four full and four partial nights within two weeks have been used to derive orbital elements of the system and discuss the validity of the Lucy model for description of the radial-velocity data. The observations had more extensive temporal coverage and better quality than similar time-sequence observations of the contact binary AW UMa. The two binaries share several physical properties and show very similar deviations from the Lucy model: the primary component is a rapidly rotating star almost unaffected by the presence of the secondary component, while the latter is embedded in a complex gas flow and appears to have its own rotation-velocity field, in contradiction to the model. The spectroscopic mass ratio is found to be larger than the one derived from the light-curve analysis, as in many other W UMa-type binaries, but the discrepancy for ɛ CrA is relatively minor, much smaller than for AW UMa. The presence of the complex velocity flows contradicting the assumption of solid-body rotation suggests a necessity of modification to the Lucy model, possibly along the lines outlined by Stȩpień in his concept of energy transfer between the binary components.

Keywords: Close binary stars, W Ursae Majoris variable stars, Spectroscopic binary stars, Astronomical techniques, Eclipsing binary stars
Stellar Oblateness versus Distant Giants in Exciting Kepler Planet Mutual Inclinations. An overabundance of single-transiting Kepler planets suggests the existence of a subpopulation of intrinsically multiplanet systems possessing large mutual inclinations. However, the origin of these mutual inclinations remains unknown. Recent work has demonstrated that mutual inclinations can be excited soon after protoplanetary disk dispersal owing to the oblateness of the rapidly rotating host star, provided that the star is tilted. Alternatively, distant giant planets, which are common in systems of close-in Kepler planets, could drive up mutual inclinations. The relative importance of each of these mechanisms has not been investigated. Here, we show that the influence of the stellar oblateness typically exceeds that of an exterior giant soon after planet formation. However, the magnitude of the resulting mutual inclinations depends critically on the timescale over which the natal disk disperses. Specifically, we find that if the disk vanishes over a timescale shorter than ∼103-4 yr, comparable to the viscous timescale of the inner ∼0.2 au, the inner planets impulsively acquire misalignments that scale with the stellar obliquity. In contrast, if the disk disperses slowly, the inner planets remain coplanar. They first align with the stellar equator but subsequently realign with the distant giant's plane as the star spins down. Our findings are consistent with recent observations that giants tend to be aligned with close-in multiplanet systems but misaligned with single-transiting planets. Stellar obliquity measurements offer a promising test of our proposed framework.

Keywords: Exoplanet dynamics, Exoplanets, Protoplanetary disks, Stellar rotation, Exoplanet formation
Modeling Radial Velocity Data of Resonant Planets to Infer Migration Histories. A number of giant-planet pairs with period ratios ≲2 discovered by the radial velocity (RV) method may reside in mean motion resonances. Convergent orbital migration and resonant capture at the time of formation would naturally explain the present-day resonant orbital configurations of these systems. Planets that experience smooth migration and eccentricity-damping forces due to a protoplanetary disk should not only be captured into mean motion resonances but also end up in a specific dynamical configuration within the resonance, sometimes referred to as apsidal corotation resonance (ACR). Here we develop a method for testing the hypothesis that a planet pair resides in an ACR by directly fitting RV data. The ACR hypothesis strongly restricts the number of free parameters describing the RV signal, and we compare fits using this highly restricted model to fits using a more conventional two-planet RV model by using nested sampling simulations. We apply our method to HD 45364 and HD 33844, two systems hosting giant-planet pairs in 3:2 and 5:3 resonances, respectively. The observations of both systems are consistent with ACR configurations, which are formally preferred based on the Bayes factors computed from nested sampling simulations. We use the results of our ACR model fits to constrain the possible migration histories of these systems.

Keywords: Exoplanet dynamics, Radial velocity, Orbital resonances
Hidden Worlds: Dynamical Architecture Predictions of Undetected Planets in Multi-planet Systems and Applications to TESS Systems. Multi-planet systems produce a wealth of information for exoplanet science, but our understanding of planetary architectures is incomplete. Probing these systems further will provide insight into orbital architectures and formation pathways. Here we present a model to predict previously undetected planets in these systems via population statistics. The model considers both transiting and non-transiting planets, and can test the addition of more than one planet. Our tests show the model's orbital period predictions are robust to perturbations in system architectures on the order of a few percent, much larger than current uncertainties. Applying it to the multi-planet systems from the Transiting Exoplanet Survey Satellite (TESS) provides a prioritized list of targets, based on predicted transit depth and probability, for archival searches and for guiding ground-based follow-up observations hunting for hidden planets.

Keywords: Exoplanets, Astrostatistics