Sazuna/UAT_keywords huggingface dataset:
The Galactic Bulge Exploration. III. Calcium Triplet Metallicities for RR Lyrae Stars. RR Lyrae stars (RRLs) are excellent tracers of stellar populations for old, metal-poor components in the the Milky Way and the Local Group. Their luminosities have a metallicity dependence, but determining spectroscopic [Fe/H] metallicities for RRLs, especially at distances outside the solar neighborhood, is challenging. Using 40 RRLs with metallicities derived from both Fe(II) and Fe(I) abundances, we verify the calibration between the [Fe/H] of RRLs from the calcium triplet. Our calibration is applied to all RRLs with Gaia Radial Velocity Spectrometer (RVS) spectra in Gaia DR3 and to 80 stars in the inner Galaxy from the BRAVA-RR survey. The coadded Gaia RVS RRL spectra provide RRL metallicities with an uncertainty of 0.25 dex, which is a factor of two improvement over the Gaia photometric RRL metallicities. Within our Galactic bulge RRL sample, we find a dominant fraction with low energies without a prominent rotating component. Due to the large fraction of such stars, we interpret these stars as belonging to the in situ metal-poor Galactic bulge component, although we cannot rule out that a fraction of these belong to an ancient accretion event such as Kraken/Heracles.

Keywords: Infrared spectroscopy, Gaia, Stellar populations, Distance measure, Galactic bulge, Distance indicators, RR Lyrae variable stars, Spectroscopy, Metallicity, Milky Way Galaxy
Astrometry and Precise Radial Velocities Yield a Complete Orbital Solution for the Nearby Eccentric Brown Dwarf LHS 1610 b. The LHS 1610 system consists of a nearby (d = 9.7 pc) M5 dwarf hosting a candidate brown dwarf companion in a 10.6 days, eccentric (e ∼ 0.37) orbit. We confirm this brown dwarf designation and estimate its mass ( 49.5‑3.5+4.3  M Jup) and inclination (114.5° ‑10.0+7.4 ) by combining discovery radial velocities (RVs) from the Tillinghast Reflector Echelle Spectrograph and new RVs from the Habitable-zone Planet Finder with the available Gaia astrometric two-body solution. We highlight a discrepancy between the measurement of the eccentricity from the Gaia two-body solution (e = 0.52 ± 0.03) and the RV-only solution (e = 0.3702 ± 0.0003). We discuss possible reasons for this discrepancy, which can be further probed when the Gaia astrometric time series become available as part of Gaia Data Release 4. As a nearby mid-M star hosting a massive short-period companion with a well-characterized orbit, LHS 1610 b is a promising target to look for evidence of sub-Alfvénic interactions and/or auroral emission at optical and radio wavelengths. LHS 1610 has a flare rate (0.28 ± 0.07 flares per day) on the higher end for its rotation period (84 ± 8 days), similar to other mid-M dwarf systems such as Proxima Cen and YZ Ceti that have recent radio detections compatible with star–planet interactions. While available Transiting Exoplanet Survey Satellite photometry is insufficient to determine an orbital phase dependence of the flares, our complete orbital characterization of this system makes it attractive to probe star–companion interactions with additional photometric and radio observations.

Keywords: Radial velocity, Astrometry, Brown dwarfs, Low mass stars
Searching for Neutral Hydrogen Escape from the 120 Myr Old Sub-Neptune HIP94235b using HST. HIP94235 b, a 120 Myr old sub-Neptune, provides us the unique opportunity to study mass loss at a pivotal stage of the system's evolution: the end of a 100 Myr old phase of intense XUV irradiation. We present two observations of HIP94235 b using the Hubble Space Telescope's Space Telescope Imaging Spectrograph in the Lyα wavelength region. We do not observe discernible differences across either the blue and red wings of the Lyα line profile in and out of transit, and report no significant detection of outflowing neutral hydrogen around the planet. We constrain the rate of neutral hydrogen escaping HIP94235 b to an upper limit of 1013 gs‑1, which remains consistent with energy-limited model predictions of 1011 gs‑1. The Lyα nondetection is likely due to the extremely short photoionization timescale of the neutral hydrogen escaping the planet's atmosphere. This timescale, approximately 15 minutes, is significantly shorter than that of any other planets with STIS observations. Through energy-limited mass loss models, we anticipate that HIP94235 b will transition into a super-Earth within a timescale of 1 Gyr.

Keywords: Exoplanet atmospheres
Gemini Planet Imager Observations of a Resolved Low-inclination Debris Disk around HD 156623. The 16 Myr old A0V star HD 156623 in the Scorpius─Centaurus association hosts a high-fractional-luminosity debris disk, recently resolved in scattered light for the first time by the Gemini Planet Imager (GPI) in polarized intensity only. We present a new analysis of the GPI H-band polarimetric detection of the HD 156623 debris disk, with particular interest in its unique morphology. This debris disk lacks a visible inner clearing, unlike the majority of low-inclination disks in the GPI sample and in Sco-Cen, and it is known to contain CO gas, positioning it as a candidate "hybrid" or "shielded" disk. We use radiative transfer models to constrain the geometric parameters of the disk based on scattered light data and thermal models to constrain the unresolved inner radius based on the system's spectral energy distribution (SED). We also compute a measurement of the polarized scattering phase function, adding to the existing sample of empirical phase function measurements. We find that HD 156623's debris disk inner radius is constrained to less than 26.6 au from scattered light imagery and less than 13.4 au from SED modeling at a 99.7% confidence interval and suggest that gas drag may play a role in retaining sub-blowout-size dust grains so close to the star.

Keywords: High contrast techniques, Polarimetry, Planetary system formation, Coronagraphic imaging, Direct imaging, Circumstellar disks, Exoplanet formation, Debris disks, Planet formation
Haro 5-2: A New Pre-main-sequence Quadruple Stellar System. We have discovered that the Hα emission-line star Haro 5-2, located in the 3─6 Myr old Ori OB1b association, is a young quadruple system. The system has a 2+2 configuration, with an outer separation of 2.″6 and with resolved subarcsecond inner binary components. The brightest component, Aa, dominates the A-binary; it is a weak-line T Tauri star with spectral type M2.5±1. The two stars of the B component are equally bright at J, but the Bb star is much redder. Optical spectroscopy of the combined B pair indicates a rich emission-line spectrum with a M3±1 spectral type. The spectrum is highly variable and switches back and forth between a classical and a weak-line T Tauri star. In the near-IR, the spectrum shows Paschen β and Brackett γ in emission, indicative of active accretion. A significant mid-IR excess reveals the presence of circumstellar or circumbinary material in the system. Most multiple systems are likely formed during the protostellar phase, involving flybys of neighboring stars followed by an inspiraling phase driven by accretion from circumbinary material and leading to compact subsystems. However, Haro 5-2 stands out among young 2+2 quadruples, as the two inner binaries are unusually wide relative to the separation of the A and B pair, allowing future studies of the individual components. Assuming the components are coeval, the system could potentially allow stringent tests of pre-main-sequence evolutionary models.

Keywords: Multiple stars, Binary stars, T Tauri stars, Young stellar objects, Pre-main sequence stars
κ Andromedae b Is a Fast Rotator from KPIC High-resolution Spectroscopy. We used the Keck Planet Imager and Characterizer to obtain high-resolution (R ∼ 35,000) K-band spectra of κ Andromedae b, a planetary-mass companion orbiting the B9V star, κ Andromedae A. We characterized its spin, radial velocity, and bulk atmospheric parameters through use of a forward-modeling framework to jointly fit planetary spectra and residual starlight speckles, obtaining likelihood-based posterior probabilities. We also detected H2O and CO in its atmosphere via cross correlation. We measured a  vsin(i)  value for κ Andromedae b of 38.42 ± 0.05 km s‑1, allowing us to extend our understanding of the population of close-in bound companions at higher rotation rates. This rotation rate is one of the highest spins relative to breakup velocity measured to date, at close to 50% of breakup velocity. We identify a radial velocity  ‑17.35‑0.09+0.05  km s‑1, which we use with existing astrometry and radial velocity measurements to update the orbital fit. We also measure an effective temperature of 1700 ± 100 K and a  log(g)  of 4.7 ± 0.5 cgs dex.

Keywords: High resolution spectroscopy, Exoplanet formation, High angular resolution, Exoplanet atmospheres
SOLES XII. The Aligned Orbit of TOI-2533 b, a Transiting Brown Dwarf Orbiting an F8-type Star. Brown dwarfs occupy a middle ground in mass space between gaseous giant planets and ultracool dwarf stars, and the characterisation of their orbital orientations may shed light on how these neighbouring objects form. We present an analysis of the Rossiter–McLaughlin effect across the transit of TOI-2533 b, a brown dwarf on a moderately eccentric (e  b  = 0.2476 ± 0.0090) and wide-separation (a  b /R ⋆ = 13.34 ± 0.30) orbit around an F8-type star, using data from the NEID/WIYN spectrograph in combination with archival photometry and radial velocity observations. Spin-orbit analyses of brown dwarfs are relatively rare, and TOI-2533 stands out as the fifth brown dwarf system with a measured spin–orbit constraint. We derive a sky-projected stellar obliquity of λ = ‑7° ± 14° for TOI-2533 b, finding that the brown dwarf is consistent with spin–orbit alignment. Our joint model also indicates that TOI-2533 b falls near the lower bound of the hydrogen-burning minimum mass range (M  b  = 74.9 ± 5.3 M Jup). Ultimately, we find that TOI-2533 b is consistent with formation from disc fragmentation in a primordially spin–orbit aligned orientation, although we cannot rule out the possibility that the system has been tidally realigned during its lifetime.

Keywords: Exoplanet dynamics, Brown dwarfs, Binary stars, Planetary alignment, Close binary stars, Exoplanet evolution, Star-planet interactions, Exoplanet formation
Spin–Orbit Coupling of the Ellipsoidal Secondary in a Binary Asteroid System. In our solar system, spin–orbit coupling is a common phenomenon in binary asteroid systems, where the mutual orbits are no longer invariant due to exchange of angular momentum between translation and rotation. In this work, dynamical structures in phase space are explored for the problem of spin–orbit coupling by taking advantage of analytical and numerical methods. In particular, the technique of Poincaré sections is adopted to reveal numerical structures, which are dependent on the total angular momentum, the Hamiltonian, mass ratio, and asphericity parameter. Analytical study based on perturbative treatments shows that high-order and/or secondary spin–orbit resonances are responsible for numerical structures arising in Poincaré sections. Analytical solutions are applied to (65803) Didymos, (80218) VO123 and (4383) Suruga to reveal their phase-space structures, showing that there is a high possibility for them to locate inside secondary 1:1 spin–orbit resonance.

Keywords: Celestial mechanics, Spin-orbit resonances, Perturbation methods, Asteroid satellites
An Efficient Observational Strategy for the Detection of the Oort Cloud. The Oort cloud is presumably a pristine relic of the solar system formation. Detection of the Oort cloud may provide information regarding the stellar environment in which the Sun was born and on the planetesimal population during the outer planets' formation phase. The best suggested approach for detecting Oort cloud objects in situ, is by searching for subsecond occultations of distant stars by these objects. Following Brown &amp; Webster, we discuss the possibility of detecting Oort cloud objects by observing near the quadrature direction. Due to the Earth's projected velocity, the occultations are longer near the quadrature direction and are therefore easier to detect, but have lower rate. We show that, for ≲1 m size telescopes, the increased exposure time will result in about one to 3 orders of magnitude increase in the number of detectable stars that have an angular size smaller than the Fresnel scale and are therefore suitable for an occultation search. We discuss the ability of this method to detect Oort cloud objects using existing survey telescopes, and we estimate the detection rate as a function of the power-law index of the size distribution of the Oort cloud objects and their distance from the Sun. We show that occultations detected using ≈1 s integration by ≲1 m telescopes at the optimal region near the quadrature points will be marginally dominated by Oort cloud objects rather than Kuiper belt objects.

Keywords: Occultation, Astronomical methods, Oort cloud objects
High-resolution Dayside Spectroscopy of WASP-189 b: Detection of Iron during the GHOST/Gemini South System Verification Run. With high equilibrium temperatures and tidally locked rotation, ultra-hot Jupiters (UHJs) are unique laboratories within which to probe extreme atmospheric physics and chemistry. In this paper, we present high-resolution dayside spectroscopy of the UHJ WASP-189 b obtained with the new Gemini High-resolution Optical SpecTrograph (GHOST) at the Gemini South Observatory. The observations, which cover 3 hr of post-eclipse orbital phases, were obtained during the instrument's System Verification run. We detect the planet's atmosphere via the Doppler cross-correlation technique, and recover a detection of neutral iron in the planet's dayside atmosphere at a significance of 7.5σ in the red arm of the data, verifying the presence of a thermal inversion. We also investigate the presence of other species in the atmosphere and discuss the implications of model injection/recovery tests. These results represent the first atmospheric characterization of an exoplanet with GHOST's high-resolution mode, and demonstrate the potential of this new instrument in detecting and studying ultra-hot exoplanet atmospheres.

Keywords: High resolution spectroscopy, Exoplanet atmospheric composition , Hot Jupiters, Exoplanet atmospheres
Utilizing Photometry from Multiple Sources to Mitigate Stellar Variability in Precise Radial Velocities: A Case Study of Kepler-21. We present a new analysis of Kepler-21, the brightest (V = 8.5) Kepler system with a known transiting exoplanet, Kepler-21 b. Kepler-21 b is a radius valley planet (R = 1.6 ± 0.2R ⊕) with an Earth-like composition (8.38 ± 1.62 g cm─3), though its mass and radius fall in the regime of possible "water worlds." We utilize new Keck/High-Resolution Echelle Spectrometer and WIYN/NEID radial velocity (RV) data in conjunction with Kepler and Transiting Exoplanet Survey Satellite (TESS) photometry to perform a detailed study of activity mitigation between photometry and RVs. We additionally refine the system parameters, and we utilize Gaia astrometry to place constraints on a long-term RV trend. Our activity analysis affirms the quality of Kepler photometry for removing correlated noise from RVs, despite its temporal distance, though we reveal some cases where TESS may be superior. Using refined orbital parameters and updated composition curves, we rule out a water world scenario for Kepler-21 b, and we identify a long-period super-Jupiter planetary candidate, Kepler-21 (c).

Keywords: Transits, Exoplanets, Stellar activity, Gaussian Processes regression, Radial velocity
Volatile Elements Characterized by MarSCoDe in Materials at Zhurong Landing Site. The study of volatile elements on the Martian surface is a critical way to explore the geological evolution history of Mars. Volatile elements such as hydrogen (H), sulfur (S), and chlorine (Cl) on the Martian surface act as proxies for the potential aqueous or atmospheric environments that formed their corresponding phases. In this work, data collected from the Laser Induced Breakdown Spectroscopy and the Short Wave Infrared Spectroscopy of the Mars Surface Composition Detection onboard the Zhurong rover are employed to analyze the volatile elements (H, S, Cl) and their carriers in materials throughout the landing site. We found that S primarily concentrates in gypsum and other sulfates, and the carriers of H include hydrous mineral combinations such as gypsum, hydrated silica, and ferrihydrite. These altered minerals are probably the products of acid weathering processes, which may have occurred mostly during the relatively humid period of the Zhurong landing site since Amazonian.

Keywords: Mars, Surface composition, Planetary surfaces
Absence of High-mass Prestellar Cores in the Orion Giant Molecular Cloud. A fundamental difference between "core-fed" and "clump-fed" star-formation theories lies in the existence or absence of high-mass cores at the prestellar stage. However, only a handful of such cores have been observed. Here, different than previous search in distributed star-formation regions in the Galactic plane, we search for high-mass prestellar cores in the Orion GMC, by observing the seven most massive starless cores selected from previous deep continuum surveys. We present ALMA Atacama Compact Array Band 6 and Band 7 continuum and line observations toward the seven cores, in which we identify nine dense cores at both bands. The derived maximum core mass is less than 11 M ⊙, based on different dust temperatures. We find no high-mass prestellar cores in this sample, aligning with the results of previous surveys, thereby challenging the existence of such cores in Orion. Outside Orion, further detailed studies are needed for remaining high-mass prestellar core candidates to confirm their status as massive, starless cores.

Keywords: Star formation, Massive stars, Dust continuum emission, Molecular clouds
KMT-2023-BLG-2669: Ninth Free-floating Planet Candidate with θ <SUB>E</SUB> Measurements. We report a free-floating planet (FFP) candidate identified from the analysis of the microlensing event KMT-2023-BLG-2669. The lensing light curve is characterized by a short duration (≲3 days) and a small amplitude (≲0.7 mag). From the analysis, we find an Einstein timescale of t E ⋍ 0.33 days and an Einstein radius of θ E ⋍ 4.41 μas. These measurements enable us to infer the lens mass as  M=8M⊕πrel/0.1mas‑1 , where π rel is the relative lens–source parallax. The inference implies that the lens is a sub-Neptune- to Saturn-mass object, depending on its unknown distance. This is the ninth isolated planetary mass microlens with θ E &lt; 10 μas, which is a useful threshold for an FFP candidate. We conduct extensive searches for possible signals of a host star in the light curve, but find no strong evidence for the host. We investigate the possibility of using late-time high-resolution imaging to probe for possible hosts. In particular, we discuss the case of finite-source point-lens FFP candidates, for which it would be possible to search for very-wide-separation hosts immediately, although such searches are "high risk, high reward."

Keywords: Gravitational microlensing exoplanet detection
An Image-based Blind Search for Fast Radio Bursts in 88 hr of Data from the EoR0 Field, with the Murchison Widefield Array. This work is part of ongoing efforts to detect fast radio bursts using the Murchison Widefield Array (MWA) in a spectral window below 300 MHz. We used an image-based method based on the pilot study of Tingay et al., scaled up via massively parallel processing using a commercial supercomputer. We searched 87.6 hr of 2 s snapshot images, each covering 1165 square degrees of the EoR0 field, over a dispersion measure range of 170–1035 pc cm‑3. The large amount of data necessitated the construction of a series of filters to classify and reject the large number of false positives. Our search was more sensitive than any previous blind search using the MWA telescope, but we report no fast radio bursts detections, a result which is consistent with the extrapolation into the low-frequency domain of the results of M. Sokolowski et al. We obtain upper bounds on the event rate ranging from &lt;1783 sky‑1 day‑1 at a fluence of 392 Jy ms, to &lt;31 sky‑1 day‑1 at 8400 Jy ms, for our spectral window of 167–198 MHz. Our method was shown to be computationally efficient and scalable by the two or three orders of magnitude required to seriously test the model of Sokolowski et al. Our process is especially sensitive to detections of satellites and meteor trails and may find applications in the identification of these transients. We comment on future surveys using this method, with both the MWA and the SKA.

Keywords: Computational methods, Radio astronomy, Radio transient sources
Modeling Multiple Radius Valley Emergence Mechanisms with Multitransiting Systems. Close-in planets smaller than Neptune form two distinct populations composed of rocky super-Earths and sub-Neptunes that may host primordial H/He envelopes. The origin of the radius valley separating these two planet populations remains an open question and has been posited to emerge either directly from the planet formation process or via subsequent atmospheric escape. Multitransiting systems that span the radius valley are known to be useful diagnostics of XUV-driven mass loss. Here, we extend this framework to test XUV-driven photoevaporation, core-powered mass loss, and an accretion-limited primordial radius valley model. Focusing on multitransiting systems allows us to eliminate unobservable quantities that are shared within individual systems such as stellar XUV luminosity histories and the properties of the protoplanetary disk. We test each proposed radius valley emergence mechanism on all 221 known multitransiting systems and calculate the minimum masses of the systems' enveloped planets to be consistent with the models. We compare our model predictions to 75 systems with measured masses and find that the majority of systems can be explained by any of the three proposed mechanisms. We also examine model consistency as a function of stellar mass and stellar metallicity but find no significant trends. More multitransiting systems with mass characterizations are required before multitransiting systems can serve as a viable diagnostic of radius valley emergence models. Our software for the model evaluations presented herein is available on GitHub and may be applied to future multitransiting system discoveries.

Keywords: Planetary system evolution, Exoplanets, Exoplanet evolution, Star-planet interactions, Exoplanet formation