Sazuna/UAT_keywords huggingface dataset:
Do Metal-rich Stars Make Metal-rich Planets? New Insights on Giant Planet Formation from Host Star Abundances. The relationship between the compositions of giant planets and their host stars is of fundamental interest in understanding planet formation. The solar system giant planets are enhanced above solar composition in metals, both in their visible atmospheres and bulk compositions. A key question is whether the metal enrichment of giant exoplanets is correlated with that of their host stars. Thorngren et al. showed that in cool (T eq &lt; 1000 K) giant exoplanets, the total heavy-element mass increases with total M  p  and the heavy-element enrichment relative to the parent star decreases with total M  p . In their work, the host star metallicity was derived from literature [Fe/H] measurements. Here we conduct a more detailed and uniform study to determine whether different host star metals (C, O, Mg, Si, Fe, and Ni) correlate with the bulk metallicity of their planets, using correlation tests and Bayesian linear fits. We present new host star abundances of 19 cool giant planet systems, and combine these with existing host star data for a total of 22 cool giant planet systems (24 planets). Surprisingly, we find no clear correlation between stellar metallicity and planetary residual metallicity (the relative amount of metal versus that expected from the planet mass alone), which is in conflict with common predictions from formation models. We also find a potential correlation between residual planet metals and stellar volatile-to-refractory element ratios. These results provide intriguing new relationships between giant planet and host star compositions for future modeling studies of planet formation.

Keywords: High resolution spectroscopy, Exoplanet formation
Gaia 19ajj: A Young Star Brightening Due to Enhanced Accretion and Reduced Extinction. We report on the source Gaia 19ajj, identifying it as a young star associated with a little-studied star-forming region seen along a complex line of sight through the Gum Nebula. The optical lightcurve recently recorded by Gaia exhibits a slow and unsteady 5.5 mag rise over about 3 yr, while the mid-infrared lightcurve from NEOWISE over the same time period shows a 1.2 mag rise having similar structure. Available color information is inconsistent with pure extinction reduction as the cause for the photometric brightening. Optical spectroscopic characteristics in the current bright phase include: little in the way of absorption except for the hallmark Li I 6707 Å signature of youth plus weak, e.g., Ca I and notably Ba II; strong wind/outflow in Ca II, Mg I b, Na I D, Hα, K I, and O I; jet signatures in [O I], [S II], [Ca II], [Fe II], and [Ni II]; and narrow rest-velocity emission in neutral species such as Fe I, Ni I, and Mg I. The infrared spectrum is also characterized by outflow and emission, including: a hot He I wind, jet lines such as [Fe II] and H2; and weak narrow rest-velocity atomic line emission. The {}12{CO} bandheads are weakly in emission, but there is also broad H2O absorption. Gaia 19ajj exhibited a previous bright state in the 2010-2012 time frame. The body of photometric and spectroscopic evidence suggests that the source bears resemblance to V2492 Cyg (PTF 10nvg) and PV Cep, both of which similarly experience bright phases that recur on long timescales, with large-amplitude photometric variations and emission-dominated spectra. We interpret the behavior of Gaia 19ajj as caused by cycles of enhanced disk accretion accompanied by reduced extinction.

Keywords: Herbig Ae/Be stars, Stellar activity, Circumstellar matter, T Tauri stars, Star formation, Stellar accretion, Stellar accretion disks
The New EXor Outburst of ESO-Hα 99 Observed by Gaia ATLAS and TESS. We report photometry and spectroscopy of the outburst of the young stellar object ESO-Hα99. The outburst was first noticed in Gaia alert Gaia18dvc and later by the Asteroid Terrestrial-impact Last Alert System (ATLAS). We have established the outburst light curve with archival ATLAS orange filter photometry, Gaia data, new V-band photometry, and J, H, and K  s  photometry from the Infrared Imaging System (IRIS) and the United Kingdom Infrared Telescope (UKIRT). The brightness has fluctuated several times near the light curve maximum. The Transiting Exoplanet Survey Satellite (TESS) satellite observed ESO-Hα 99 with high cadence during one of these minor minima and found brightness fluctuations on timescales of days and hours. Imaging with UKIRT shows the outline of an outflow cavity, and we find one knot of {{{H}}}2 1-0 S(1) emission, now named MHO 1520, on the symmetry axis of this nebula, indicating recent collimated outflow activity from ESO-Hα 99. Its pre-outburst SED shows a flat far-infrared spectrum, confirming its early evolutionary state and its similarity to other deeply embedded objects in the broader EXor class. The pre-outburst luminosity is 34 L ⊙, a much higher luminosity than typical EXors, indicating that ESO-Hα 99 may be a star of intermediate mass. Infrared and optical spectroscopy show a rich emission-line spectrum, including H I lines, strong red Ca II emission, as well as infrared CO bandhead emission, all characteristic EXors in the broadest sense. Comparison of the present spectra with an optical spectrum obtained in 1993, presumably in the quiescent state of the object, shows that during the present outburst the continuum component of the spectrum has increased notably more than the emission lines. The Hα equivalent width during the outburst is down to one-half of its 1993 level, and shock-excited emission lines are much less prominent.

Keywords: Eruptive variable stars, Stellar jets, Flash spectra, T Tauri stars, Young stellar objects, Infrared photometry
Compositions of Planetary Debris around Dusty White Dwarfs. The photospheres of some white dwarfs (WDs) are “polluted” by accretion of material from their surrounding planetary debris. WDs with dust disks are often heavily polluted and high-resolution spectroscopic observations of these systems can be used to infer the chemical compositions of extrasolar planetary material. Here, we report spectroscopic observation and analysis of 19 WDs with dust disks or candidate disks. The overall abundance pattern very much resembles that of bulk Earth and we are starting to build a large enough sample to probe a wide range of planetary compositions. We found evidence for accretion of Fe-rich material onto two WDs as well as O-rich but H-poor planetary debris onto one WD. In addition, there is a spread in Mg/Ca and Si/Ca ratios and it cannot be explained by differential settling or igneous differentiation. The ratios appear to follow an evaporation sequence. In this scenario, we can constrain the mass and number of evaporating bodies surrounding polluted WDs.

Keywords: White dwarf stars, Chemical abundances, Circumstellar disks
A Search for Multiplanet Systems with TESS Using a Bayesian N-body Retrieval and Machine Learning. Transiting exoplanets in multiplanet systems exhibit non-Keplerian orbits as a result of the gravitational influence from companions, which can cause the times and durations of transits to vary. The amplitude and periodicity of the transit time variations are characteristic of the perturbing planet’s mass and orbit. The objects of interest from the Transiting Exoplanet Survey Satellite (TESS) are analyzed in a uniform way to search for transit timing variations (TTVs) with sectors 1-3 of data. Due to the volume of targets in the TESS candidate list, artificial intelligence is used to expedite the search for planets by vetting nontransit signals prior to characterizing the light-curve time series. The residuals of fitting a linear orbit ephemeris are used to search for TTVs. The significance of a perturbing planet is assessed by comparing the Bayesian evidence between a linear and nonlinear ephemeris, which is based on an N-body simulation. Nested sampling is used to derive posterior distributions for the N-body ephemeris and in order to expedite convergence, custom priors are designed using machine learning. A dual-input, multi-output convolutional neural network is designed to predict the parameters of a perturbing body given the known parameters and measured perturbation (O - C). There is evidence for three new multiplanet candidates (WASP-18, WASP-126, TOI 193) with nontransiting companions using the two-minute cadence observations from TESS. This approach can be used to identify stars in need of longer radial velocity and photometric follow-up than those already performed.

Keywords: Observational astronomy, Exoplanet dynamics, Exoplanet catalogs, Neural networks, Nested sampling, Convolutional neural networks, Exoplanet astronomy, N-body problem, N-body simulations
A Hubble PanCET Study of HAT-P-11b: A Cloudy Neptune with a Low Atmospheric Metallicity. We present the first comprehensive look at the 0.35-5 μm transmission spectrum of the warm (∼800 K) Neptune HAT-P-11b derived from 13 individual transits observed using the Hubble and Spitzer Space Telescopes. Along with the previously published molecular absorption feature in the 1.1-1.7 μm bandpass, we detect a distinct absorption feature at 1.15 μm and a weak feature at 0.95 μm, indicating the presence of water and/or methane with a combined significance of 4.4σ. We find that this planet’s nearly flat optical transmission spectrum and attenuated near-infrared molecular absorption features are best matched by models incorporating a high-altitude cloud layer. Atmospheric retrievals using the combined 0.35-1.7 μm Hubble Space Telescope (HST) transmission spectrum yield strong constraints on atmospheric cloud-top pressure and metallicity, but we are unable to match the relatively shallow Spitzer transit depths without underpredicting the strength of the near-infrared molecular absorption bands. HAT-P-11b’s HST transmission spectrum is well matched by predictions from our microphysical cloud models. Both forward models and retrievals indicate that HAT-P-11b most likely has a relatively low atmospheric metallicity (&lt;4.6 Z ⊙ and &lt;86 Z ⊙ at the 2σ and 3σ levels respectively), in contrast to the expected trend based on the solar system planets. Our work also demonstrates that the wide wavelength coverage provided by the addition of the HST STIS data is critical for making these inferences.

Keywords: Exoplanet atmospheric composition , Exoplanet atmospheres
Accretion Kinematics in the T Tauri Binary TWA 3A: Evidence for Preferential Accretion onto the TWA 3A Primary. We present time-series, high-resolution optical spectroscopy of the eccentric T Tauri binary TWA 3A. Our analysis focuses on variability in the strength and structure of the accretion-tracing emission lines Hα and He I 5876 Å. We find emission line strengths to display the same orbital phase-dependent behavior found with time-series photometry, namely, bursts of accretion near periastron passages. Such bursts are in good agreement with numerical simulations of young eccentric binaries. During accretion bursts, the emission of He I 5876 Å consistently traces the velocity of the primary star. After removing a model for the system’s chromospheric emission, we find the primary star typically emits ∼70% of the He I accretion flux. We interpret this result as evidence for circumbinary accretion streams that preferentially feed the TWA 3A primary. This finding is in contrast to most numerical simulations, which predict the secondary should be the dominant accretor in a binary system. Our results may be consistent with a model in which the precession of an eccentric circumbinary disk gap alternates between preferentially supplying mass to the primary and secondary.

Keywords: Binary stars, Close binary stars, Circumstellar disks, Stellar astronomy, T Tauri stars, Young stellar objects, Star formation, Protoplanetary disks, Stellar accretion, Low mass stars, Stellar accretion disks, Trinary stars
Solar Neighborhood Kinematics from Gaia -LAMOST Dwarf Stars. We use high-precision kinematic data from Gaia data release 2 (DR2) and spectroscopic data from Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) data release 5 (DR5) to explore the kinematics of solar neighborhood dwarf stars in the northern and southern sides of the Galactic plane. The metallicity range of the sampled stars is -0.5 &lt; [Fe/H] &lt; 0.5. Systematic north-south asymmetries in stellar radial motion and rotation are detected: stars in the north disk are moving toward the outer disk, while stars in the south disk have inward-streaming motion toward the Galactic center; stars in the north disk rotate slower than stars in the south disk in general. The tilt angle is antisymmetric about the Galactic plane: for an assumed Galactocentric distance of the Sun, R 0 = 8.122 kpc, the increase in the tilt angle α  Rz  with the vertical distance z is well described by the relation {α }{Rz}=(1.11+/- 0.11)\arctan (z/{R}0)-(0.0069+/- 0.0034). The variation of stellar kinematics with the vertical distance to the Galactic plane has no essential dependence on the metallicity.

Keywords: Stellar kinematics, Solar neighborhood, Milky Way Galaxy physics, Milky Way disk, Galaxy kinematics
Asteroseismology of the Multiplanet System K2-93. We revisit the analysis of the bright multiplanet system K2-93, discovered with data taken by the K2 mission. This system contains five identified planets ranging in size from sub-Neptune to Jupiter size. The K2 data available at the discovery of the system only showed single transits for the three outer planets, which allowed weak constraints to be put on their periods. As these planets are interesting candidates for future atmospheric studies, a better characterization of the host star and tighter constraints on their orbital periods are essential. Using new data from the K2 mission taken after the discovery of the system, we perform an asteroseismic characterization of the host star. We are able to place strong constraints on the stellar parameters and obtain a value for the stellar mass of {1.22}-0.02+0.03 {M}⊙ , a stellar radius of 1.30 ± 0.01 R ⊙, and an age of {2.07}-0.27+0.36 Gyr. Put together with the additional transits identified for two of the three outer planets, we constrain the orbital periods of the outer planets and provide updated estimates for the stellar reflex velocities induced by the planets.

Keywords: Exoplanets, Fundamental parameters of stars, Planet hosting stars, Stellar oscillations, Asteroseismology
Super Metal-rich Stars in the LAMOST Survey: A Test on Radial Migration. Super metal-rich stars with [Fe/H] &gt; 0.4 are selected from LAMOST DR6, and two groups, the blue and the red, are found in the T eff versus logg diagram with a temperature gap between them. In combination with Gaia DR2, stellar positions, velocities, and orbits are calculated, and spatial distributions, kinematical properties, and orbital parameters are compared between the two groups. The blue group shows mainly thin-disk kinematics and spans a wide R range of 6-12 kpc, while the red group has both the thin-disk and the thick-disk kinematics with a narrower range of R = 6-10 kpc. The kinematical and orbital parameters of stars in the blue group indicate that they could belong to the young population with age less than 1 Gyr, rather than blue stragglers of the old population. The orbital parameters, R  p , R  a , and R  g , of the red group with the thick-disk kinematics are smaller than those with the thin-disk kinematics. The distributions of birth radius and migration distance indicate that radial migration is a favorable origin for the red group, especially those with the thick-disk kinematics, but not for the blue group. The relative magnitude of radial migration is of 51% for the whole sample and of 64% for the red group only. The corotation radial migration caused by the bars and spiral arms at resonances is the most likely mechanism for explaining these properties of SMR stars in this work.

Keywords: Milky Way evolution, Milky Way disk, Milky Way dynamics
Compact Survey Telescope with a Diameter of 3.6 m. An optical layout of a corrected Cassegrain telescope with an aperture of 3.6 m (f/3.0) and a 2.°5 field of view is proposed. The primary and secondary mirrors are standard hyperboloids; all five corrector lenses are made of fused silica and have spherical surfaces. The total length of the optical system is 4.36 m. The rms spot diameter in the “g,” “r,” “i” integral waveband of 0.40-0.82 μm is about 0.″3 across the flat focal surface; the D 80 star diameter is about 0.″4. Due to the low light vignetting, the effective aperture diameter reaches 3.3 m. The comparative simplicity and compactness of the optical layout allow us to consider this system promising for conducting deep sky surveys.

Keywords: Optical telescopes, Catadioptric telescopes, Wide-field telescopes
A Reanalysis of the UVES M Dwarf Planet Search Program. The UVES (Ultraviolet and Visible Spectrometer) M Dwarf Planet Search program surveyed 40 M dwarfs and 1 M giant from 2000 through 2007 March. Two of the M dwarfs were double-lined spectroscopic binaries. The 38 single-lined M dwarfs in this survey are among the nearest and brightest M dwarfs. Starting with the reduced 1D spectra provided by the UVES team, we reanalyzed the UVES velocities of Proxima Cen as part of the “Pale Red Dot” program. The velocity rms decreased from 3.6 to 2.3 m s-1. Motivated by this result, we have harvested all of the raw data from the UVES M Dwarf Planet Search from the European Southern Observatory (ESO) archives and have written custom packages to generate 1D spectra from the raw data, and velocities from the 1D spectra. The median improvement in the velocity rms from the new analysis is 1.8 m s-1. Six of the 38 M dwarfs from the original study had a velocity rms &lt; 4 m s-1. In the reanalysis presented here, 22 of these stars have a velocity rms &lt; 4 m s-1. We improve the upper limits on possible planets orbiting these stars by a factor of typically two to three. For many of these M dwarfs, these observations represent the first epoch of high-precision velocity measurements. Based on observations collected at the European Southern Observatory, Paranal Chile, ESO programs 65.L-0428, 66.C-0446, 267.C-5700, 68.C-0415, 69.C-0722, 70.C-0044,71.C-0498, 072.C-0495, 173.C-0606, 078.C-0829.

Keywords: Radial velocity, Exoplanets
Upper Limits for Emissions in the Coma of Comet 67P/Churyumov-Gerasimenko near Perihelion as Measured by Rosetta’s Alice Far-UV Spectrograph. The Alice far-UV imaging spectrograph (700-2050 Å) acquired over 70,000 spectral images during Rosetta’s 2 yr escort mission, including over 20,000 in the months surrounding perihelion when the comet activity level was highest. We have developed automated software to fit and remove ubiquitous H, O, C, S, and CO emissions from Alice spectra, along with reflected solar continuum and absorption from gaseous H2O in the comet’s coma, which we apply to a grand sum of integrations taken near perihelion. We present upper limits on the presence of 1 ion and 17 neutral atomic species for this time period. These limits are compared to results obtained by other Rosetta instruments where possible, as well as to CI carbonaceous chondrites and solar photospheric abundances.

Keywords: Ultraviolet astronomy, Short period comets
Low-frequency Radio Absorption in Tycho’s Supernova Remnant. Tycho’s supernova remnant (SNR) is the remnant of the SN Ia explosion SN1572. In this work we present new low-frequency radio observations with the LOw Frequency ARray (LOFAR) Low-band and High-band Antennae, centered at 58 MHz and 143 MHz, and with an angular resolution of 41″ and 6″, respectively. We compare these maps to Very Large Array maps at 327 MHz and 1420 MHz, and detect the effect of low-frequency absorption in some regions of the remnant due to the presence of free electrons along the line of sight. We investigate two origins for the low-frequency free-free absorption that we observe: external absorption from the foreground and internal absorption from Tycho’s unshocked ejecta. The external absorption could be due to an ionized thin, diffuse cavity surrounding the SNR (although this cavity would need to be very thin to comply with the neutral fraction required to explain the remnant’s optical lines), or it could be due to an over-ionized molecular shell in the vicinity of the remnant. We note that possible ionizing sources are the X-ray emission from Tycho, its cosmic rays, or radiation from Tycho’s progenitor. For the internal absorption, we are limited by our understanding of the spectral behavior of the region at unabsorbed radio frequencies. However, the observations are suggestive of free-free absorption from unshocked ejecta inside Tycho’s reverse shock.

Keywords: Supernova remnants, Interstellar absorption, Molecular clouds, Interstellar plasma
Quantifying the Evolution of Molecular Production Rates of Comet 21P/Giacobini-Zinner with iSHELL/NASA-IRTF. This paper presents results from our molecular characterization of comet 21P/Giacobini-Zinner during its 2018 apparition. We followed the comet during four observing runs, for a total of eight nights. The high-resolution spectra of 21P were acquired using iSHELL—the near-infrared high-resolution immersion echelle spectrograph on NASA/IRTF (Maunakea, Hawaii). We detected many cometary emission lines across four customized iSHELL settings in the (2.9-5.2) μm range. CO abundances relative to water displayed a relatively constant behavior during the observing campaign, suggesting a possible correlation between the outgassing of water and CO. While CO mixing ratios in 21P are consistent with the reference median value for Jupiter family comets (JFCs), ethane was depleted relative to the reference median value for JFCs, except for one observing run (August 8 and 9) in which ethane appeared overabundant. We consider several possible causes: an ethane outburst, decreasing outgassing of water, or a seasonal effect owing to nucleus rotation. In the pre-perihelion runs, methanol was overabundant compared with the reference median value for JFCs, however it decreased steadily to a depleted value during 21P’s post-perihelion phase, suggesting a possible seasonal effect. We report 3σ upper limits for acetylene, formaldehyde, ammonia, and methane. The ratios of our measured 3σ upper limits for acetylene and detections of hydrogen cyanide are consistent with the depletion of C2 relative to CN in 21P observed at optical wavelengths. This result confirms that 21P is depleted in the carbon-chain primary volatile responsible for C2 production.

Keywords: High resolution spectroscopy, Small Solar System bodies, Comae, Molecular spectroscopy, Short period comets, Spectroscopy, Comets