Sazuna/UAT_keywords huggingface dataset:
In the Presence of a Wrecking Ball: Orbital Stability in the HR 5183 System. Discoveries of exoplanets using the radial velocity method are progressively reaching out to increasingly longer orbital periods as the duration of surveys continues to climb. The improving sensitivity to potential Jupiter analogs is revealing a diversity of orbital architectures that are substantially different from that found in our solar system. An excellent example of this is the recent discovery of HR 5183b: a giant planet on a highly eccentric (e = 0.84) ∼75 yr orbit. The presence of such giant planet orbits are intrinsically interesting from the perspective of the dynamical history of planetary systems, and also for examining the implications of ongoing dynamical stability and habitability of these systems. In this work, we examine the latter, providing results of dynamical simulations that explore the stable regions that the eccentric orbit of the HR 5183 giant planet allows to exist within the habitable zone (HZ) of the host star. Our results show that, despite the incredible perturbing influence of the giant planet, there remain a narrow range of locations within the HZ where terrestrial planets may reside in long-term stable orbits. We discuss the effects of the giant planet on the potential habitability of a stable terrestrial planet, including the modulation of terrestrial planet eccentricities and the periodically spectacular view of the giant planet from the terrestrial planet location.

Keywords: Exoplanets, Elliptical orbits, Orbital evolution, Astrobiology, Habitable zone, Habitable planets
Hubble Space Telescope Flux Calibration. I. STIS and CALSPEC. The precision of absolute flux measurements is quantified for the Space Telescope Imaging Spectrograph (STIS), which is the most important contributor to the CALSPEC standards. With our goal of 1% absolute accuracy, the documentation of the Hubble Space Telescope/CALSPEC flux scale and its subpercent repeatability are of prime importance. While the 1σ rms broadband repeatability for G140L is 0.7%, the other four STIS spectral modes show excellent photometric repeatability of 1σ = 0.2%. The custom data processing that is required to achieve these results is discussed in detail. In particular, the correction for the wide extraction heights required for the saturated Vega and Sirius data is found to vary with time, which results in revised spectral energy distributions that decrease by as much as 2.5% for Sirius and 2% for Vega at 1 μm.

Keywords: Spectrophotometric standards
OGLE-2015-BLG-1649Lb: A Gas Giant Planet around a Low-mass Dwarf. We report the discovery of an exoplanet from the analysis of the gravitational microlensing event OGLE-2015-BLG-1649 that challenges the core accretion model of planet formation and appears to support the disk instability model. The planet/host-star mass ratio is q = 7.2 × 10-3 and the projected separation normalized to the angular Einstein radius is s = 0.9. We conducted high-resolution follow-up observations using the Infrared Camera and Spectrograph (IRCS) camera on the Subaru telescope and are able to place an upper limit on the lens flux. From these measurements we are able to exclude all host stars greater than or equal in mass to a G-type dwarf. We conducted a Bayesian analysis with these new flux constraints included as priors resulting in estimates of the masses of the host star and planet. These are M L = 0.34 ± 0.19 M ⊙ and {M}{{p}}={2.5}-1.4+1.5 {M}Jup}, respectively. The distance to the system is {D}{{L}}={4.23}-1.64+1.51 {kpc}. The projected star-planet separation is {a}\perp ={2.07}-0.77+0.65 {au}. The estimated relative lens-source proper motion, ∼7.1 mas yr-1, is fairly high and thus the lens can be better constrained if additional follow-up observations are conducted several years after the event.

Keywords: Gravitational microlensing, Exoplanet astronomy
CCD Measurements of Double and Multiple Stars at ASV and NAO Rozhen in 2017 and 2018. We give the results of CCD observations for 789 double or multiple stars obtained during 2017 and 2018. These observations were carried out at both the Serbian Astronomical Station on the mountain of Vidojevica (ASV) and the Bulgarian National Astronomical Observatory at Rozhen (NAOR). They were performed using three telescopes, the 1.4 and 0.6 m telescopes at ASV, and the 2 m telescope at NAOR. The total of 1196 measurements (position angle and angular separation) for the 939 pairs is presented. Out of this number, 55 pairs have calculated orbital or linear elements and for them the residuals are given. Some pairs have measurements for several epochs. Measured angular separations are in the interval from 1.″51 to 208.″81, with a median separation of 4.″16. Two new pairs and linear elements for three pairs, which are calculated for the first time, are also presented.

Keywords: CCD observation, Parallax, Angular separation, Proper motions, Visual binary stars
Investigating Trends in Atmospheric Compositions of Cool Gas Giant Planets Using Spitzer Secondary Eclipses. We present new 3.6 and 4.5 μm secondary eclipse measurements for five cool (T ≲ 1000 K) transiting gas giant planets: HAT-P-15b, HAT-P-17b, HAT-P-18b, HAT-P-26b, and WASP-69b. We detect eclipses in at least one bandpass for all planets except HAT-P-15b. We confirm and refine the orbital eccentricity of HAT-P-17b, which is also the only planet in our sample with a known outer companion. We compare our measured eclipse depths in these two bands, which are sensitive to the relative abundances of methane versus carbon monoxide and carbon dioxide, respectively, to predictions from 1D atmosphere models for each planet. For planets with hydrogen-dominated atmospheres and equilibrium temperatures cooler than ∼1000 K, this ratio should vary as a function of both atmospheric metallicity and the carbon-to-oxygen ratio. For HAT-P-26b, our observations are in good agreement with the low atmospheric metallicity inferred from transmission spectroscopy. We find that all four of the planets with detected eclipses are best matched by models with relatively efficient circulation of energy to the nightside. We see no evidence for a solar-system-like correlation between planet mass and atmospheric metallicity, but instead identify a potential (1.9σ) correlation between the inferred CH4/(CO + CO2) ratio and stellar metallicity. Our ability to characterize this potential trend is limited by the relatively large uncertainties in the stellar metallicity values. Our observations provide a first look at the brightness of these planets at wavelengths accessible to the James Webb Space Telescope, which will be able to resolve individual CH4, CO, and CO2 bands and provide much stronger constraints on their atmospheric compositions.

Keywords: Exoplanet atmospheric composition , Exoplanets, Exoplanet atmospheres, Broad band photometry, Infrared photometry
Visual Orbits of Spectroscopic Binaries with the CHARA Array. II. The Eclipsing Binary HD 185912. We present the visual orbit of the double-lined eclipsing binary, HD 185912, from long baseline interferometry with the CHARA Array. We also obtain echelle spectra from the Apache Point observatory to update the spectroscopic orbital solution and analyze new photometry from Burggraaff et al. to model the eclipses. By combining the spectroscopic and visual orbital solutions, we find component masses of M 1 = 1.361 ± 0.004 M ☉ and M 2 = 1.331 ± 0.004 M ☉, and a distance of d = 40.75 ± 0.30 pc from orbital parallax. From the light-curve solution, we find component radii of R 1 = 1.348 ± 0.016 R ☉ and R 2 = 1.322 ± 0.016 R ☉. By comparing these observed parameters to stellar evolution models, we find that HD 185912 is a young system near the zero age main sequence with an estimated age of 500 Myr.

Keywords: Binary stars, Fundamental parameters of stars, Spectroscopic binary stars, Eclipsing binary stars, Interferometric binary stars
Investigating the Temperature Distribution of Diatomic Carbon in Comets Using the Swan Bands. We present high spectral resolution observations of comets 122P/de Vico and 153P/Ikeya-Zhang obtained with the Tull Coudé spectrograph on the 2.7 m Harlan J. Smith telescope of McDonald Observatory. We used these data to study the distribution of the lines of the {{{d}}}3{{{\Pi }}}g{--}{{{a}}}3{{{\Pi }}}u C2 (Swan) bands. We show that the data are best represented with two rotational temperatures, with the lowest energy lines being at a relatively cool temperature and the higher energy lines being at a higher temperature. We discuss the implications of this two-temperature distribution and suggest future work.

Keywords: High resolution spectroscopy, Comets, Molecular spectroscopy, Comae
Spectroscopic Orbits of Subsystems in Multiple Stars. VI.. Thirteen spectroscopic orbits of late-type stars are determined from the high-resolution spectra taken with the CHIRON echelle spectrometer at the 1.5 m Cerro Tololo Inter-American Observatory telescope. Most (HIP 14194B, 40523A, 41171A, 51578A, 57572B, 59426A, 62852B, 66438A, 87813B, and 101472A) are inner subsystems in hierarchical multiple stars with three or four components. The periods range from 2.2 to 1131 days. Masses of the components, orbital inclinations, and projected rotation velocities are estimated, and the presence or absence of the lithium line is noted. In addition to those systems, HIP 57021 is a simple 54 day twin binary, and HIP 111598 is a compact triple-lined system with periods of 5.9 and 271 days. This object is likely old, but, nevertheless, the secondary component in the inner pair does not rotate synchronously with the orbit. The period-eccentricity diagram of 528 known inner low-mass spectroscopic subsystems (including 36 from this paper series) is given. The distribution of the inner periods is smooth, without any details around the tidal circularization period of ∼10 days.

Keywords: Trinary stars, Multiple stars, Binary stars
Kinematics of the Palomar 5 Stellar Stream from RR Lyrae Stars. Thin stellar streams, formed from the tidal disruption of globular clusters, are important gravitational tools, sensitive to both global and small-scale properties of dark matter. The Palomar 5 stellar stream (Pal 5) is an exemplar stream within the Milky Way: its ∼20° tidal tails connect back to the progenitor cluster, and the stream has been used to study the shape, total mass, and substructure fraction of the dark matter distribution of the Galaxy. However, most details of the phase-space distribution of the stream are not fully explained, and dynamical models that use the stream for other inferences are therefore incomplete. Here we aim to measure distance and kinematic properties along the Pal 5 stream in order to motivate improved models of the system. We use a large catalog of RR Lyrae-type stars (RRLs) with astrometric data from the Gaia mission to probabilistically identify RRLs in the Pal 5 stream. RRLs are useful because they are intrinsically luminous standard candles and their distances can be inferred with small relative precision (∼3%). By building a probabilistic model of the Pal 5 cluster and stream in proper motion and distance, we find 27 RRLs consistent with being members of the cluster (10) and stream (17). Using these RRLs, we detect gradients in distance and proper motion along the stream, and provide an updated measurement of the distance to the Pal 5 cluster using the RRLs, d=20.6+/- 0.2 {kpc}. We provide a catalog of Pal 5 RRLs with inferred membership probabilities for future modeling work.

Keywords: Globular star clusters, RR Lyrae variable stars, Milky Way stellar halo, Milky Way dynamics
MOA-bin-29b: A Microlensing Gas-giant Planet Orbiting a Low-mass Host Star. We report the discovery of a gas-giant planet orbiting a low-mass host star in the microlensing event MOA-bin-29 that occurred in 2006. We find five degenerate solutions with the planet/host-star mass ratio of q ∼ 10-2. The Einstein radius crossing time of all models are relatively short (∼4-7 days), which indicates that the mass of host star is likely low. The measured lens-source proper motion is 5-9 mas yr-1 depending on the models. Since only finite source effects are detected, we conduct a Bayesian analysis in order to obtain the posterior probability distribution of the lens physical properties. As a result, we find the lens system is likely to be a gas-giant orbiting a brown dwarf or a very late M-dwarf in the Galactic bulge. The probability distributions of the physical parameters for the five degenerate models are consistent within the range of error. By combining these probability distributions, we conclude that the lens system is a gas giant with a mass of {M}{{p}}={0.63}-0.39+1.13 {M}Jup} orbiting a brown dwarf with a mass of {M}{{h}}={0.06}-0.04+0.11 {M}⊙  at a projected star-planet separation of {r}\perp ={0.53}-0.18+0.89 {au}. The lens distance is {D}{{L}}={6.89}-1.19+1.19 {kpc}, i.e., likely within the Galactic bulge.

Keywords: Gravitational microlensing, Exoplanets
Detection of a Low-mass Stellar Companion to the Accelerating A2IV Star HR 1645. The ∼500 Myr A2IV star HR 1645 has one of the most significant low-amplitude accelerations of nearby early-type stars measured from a comparison of the Hipparcos and Gaia astrometric catalogs. This signal is consistent with either a stellar companion with a moderate mass ratio (q ∼ 0.5) on a short period (P &lt; 1 yr), or a substellar companion at a separation wide enough to be resolved with ground-based high-contrast imaging instruments; long-period equal-mass ratio stellar companions that are also consistent with the measured acceleration are excluded with previous imaging observations. The small but significant amplitude of the acceleration made HR 1645 a promising candidate for targeted searches for brown dwarf and planetary-mass companions around nearby, young stars. In this paper we explore the origin of the astrometric acceleration by modeling the signal induced by a wide-orbit M8 companion discovered with the Gemini Planet Imager, as well as the effects of an inner short-period spectroscopic companion discovered a century ago but not since followed up. We present the first constraints on the orbit of the inner companion, and demonstrate that it is a plausible cause of the astrometric acceleration. This result demonstrates the importance of vetting of targets with measured astrometric acceleration for short-period stellar companions prior to conducting targeted direct imaging surveys for wide-orbit substellar companions.

Keywords: Close binary stars, Coronagraphic imaging, Astrometry, Radial velocity, Visual binary stars
HyDRA-H: Simultaneous Hybrid Retrieval of Exoplanetary Emission Spectra. High-resolution Doppler spectroscopy has been used to detect several chemical species in exoplanetary atmospheres. Such detections have traditionally relied on cross correlation of observed spectra against spectral model templates, an approach that is successful for detecting chemical species but not optimized for constraining abundances. Recent work has explored ways to perform atmospheric retrievals on high-resolution spectra (HRS) and combine them with retrievals routinely performed for low-resolution spectra (LRS) by developing a mapping from the cross-correlation function to a likelihood metric. We build upon previous studies and report HyDRA-H, a hybrid retrieval code for simultaneous analysis of low- and high- resolution thermal emission spectra of exoplanets in a fully Bayesian approach. We demonstrate HyDRA-H on the hot Jupiter HD 209458b as a case study. We validate our HRS retrieval capability by confirming previous results and report a simultaneous hybrid retrieval using both HRS and LRS data. The LRS data span the HST WFC3 (1.1-1.7 μm) and Spitzer photometry (IRAC 3.6-8 μm) bands, while the HRS data were obtained with CRIRES on VLT at 2.3 μm. The constraints on the composition and temperature profiles for the hybrid retrieval are more stringent than retrievals with either LRS or HRS data sets individually. We retrieve abundances of {log}({{{H}}}2{{O}})=-{4.11}-0.30+0.91 and {log}({CO})=-{2.16}-0.47+0.99, and C/O = {0.99}-0.02+0.01, consistent with previous works. We constrain the photospheric temperature to be {1498}-57+216 K, consistent with the equilibrium temperature. Our results demonstrate the significant advantages of hybrid retrievals by combining strengths of both HRS and LRS observations, which probe complementary aspects of exoplanetary atmospheres.

Keywords: High resolution spectroscopy, Exoplanet atmospheric composition , Exoplanets, Hot Jupiters, Spectroscopy, Exoplanet atmospheres
Ultraviolet Imaging Telescope View of Dwarf Irregular Galaxy IC 2574: Is the Star Formation Triggered Due to Expanding H I Shells?. Star-forming dwarf galaxies in the local volume are diverse and ideal test beds to understand the details of star formation in a variety of environments. Here we present a deep far-UV (FUV) imaging study of the nearby dwarf irregular galaxy IC 2574 using the Ultraviolet Imaging Telescope. We identified 419 FUV-bright regions with radii between 15 and 285 pc in the galaxy and found that 28.6% of them are located in H I shells, 12.6% inside holes, and 60.1% away from the holes. The H I column density is found to be more than 1021 cm-2 for 82.3% of the identified regions. Thirty of the 48 H I holes show triggered star formation in their shells, while 16 holes do not show any related FUV emission. Cross-matching with Hα emission, we found that 23 holes have both FUV and Hα emission in their shells, signifying a very recent trigger. Therefore, star formation in the galaxy has been partly triggered due to the expanding H I holes, whereas in the majority of the sites, it is driven by other mechanisms. Irrespective of the location, larger star-forming complexes were found to have multiple substructures. We report two resolved components for the remnant cluster of the supergiant shell and estimate their masses. The star formation rate of IC 2574 is found to be 0.57 M ⊙ yr-1, which is slightly higher compared to the average value of other nearby dwarf irregular galaxies.

Keywords: Dwarf galaxies, Star formation
IRAS 09002-4732: A Laboratory for the Formation of Rich Stellar Clusters. IRAS 09002-4732 is a poorly studied embedded cluster of stars in the Vela Molecular Ridge at a distance of 1.7 kpc. Deep observations with the Chandra X-ray Observatory, combined with existing optical and infrared surveys, produce a catalog of 441 probable pre-main-sequence members of the region. The stellar spatial distribution has two components: most stars reside in a rich, compact, elliptical cluster, but a minority reside within a molecular filament several parsecs long that straddles the cluster. The filament has active distributed star formation with dozens of unclustered protostars. The cluster pre-main-sequence population is ≤0.8 Myr old and deeply embedded; its most massive member is extremely young, producing an ultracompact H II region. The cluster total population deduced from the X-ray luminosity function is surprisingly rich, twice that of the Orion Nebula Cluster. The cluster core is remarkably dense where strong N-body interactions should be occurring; its initial mass function may be deficient in massive stars. We infer that IRAS 09002-4732 is a rare case where a rich cluster is forming today in a molecular filament, consistent with astrophysical models of cluster formation in clouds that involve the hierarchical formation and merging of groups in molecular filaments.

Keywords: Compact H II region, Interstellar filaments, Star forming regions, Young star clusters, Dense interstellar clouds, Infrared excess, Pre-main sequence, Protostars, Single x-ray stars, Collapsing clouds
New Constraint on the Atmosphere of (50000) Quaoar from a Stellar Occultation. We report observations of a stellar occultation by the classical Kuiper Belt object (50000) Quaoar that occurred on 2019 June 28. A single-chord high-cadence (2 Hz) photometry data set was obtained with the Tomo-e Gozen CMOS camera mounted on the 1.05 m Schmidt telescope at Kiso Observatory. The obtained ingress and egress data do not show any indication of atmospheric refraction and allow new 1σ and 3σ upper limits of 6 and 16 nbar, respectively, to be set for the surface pressure of a pure methane atmosphere. These upper limits are lower than the saturation vapor pressure of methane at Quaoar’s expected mean surface temperature (T ∼ 44 K) and imply the absence of a ∼10 nbar-level global atmosphere formed by methane ice on Quaoar’s surface.

Keywords: Kuiper belt, Classical Kuiper belt objects, Solar system, Trans-Neptunian objects, Solar system astronomy
Image Flux Ratios of Gravitationally Lensed HS 0810+2554 with High-resolution Infrared Imaging. We report near simultaneous imaging using LMIRCam on the LBTI of the quadruply imaged lensed quasar HS 0810+2554 at wavelengths of 2.16, 3.7, and 4.78 μm with a full width at half maximum spatial resolution of 0.″13, 0.″12, and 0.″15 respectively, comparable to Hubble Space Telescope optical imaging. In the z = 1.5 rest frame of the quasar, the observed wavelengths correspond to 0.86, 1.48, and 1.91 μm respectively. The two brightest images in the quad, A and B, are clearly resolved from each other with a separation of 0.″187. The flux ratio of these two images (A/B) trends from 1.79 to 1.23 at wavelengths from 2.16 to 4.78 μm. The trend in flux ratio is consistent with the 2.16 μm flux originating from a small sized accretion disk in the quasar that experiences only microlensing. The excess flux above the contribution from the accretion disk at the two longer wavelengths originates from a larger sized region that experiences no microlensing. A simple model employing multiplicative factors for image B due to stellar microlensing (m) and substructure millilensing (M) is presented. The result is tightly constrained to the product m × M = 1.79. Given the observational errors, the 60% probability contour for this product stretches from m = 2.6, M = 0.69 to m = 1.79, M = 1.0, where the later is consistent with microlensing only.

Keywords: Cosmology, Strong gravitational lensing, Dark matter
An Integrable Model for the Dynamics of Planetary Mean-motion Resonances. I consider the dynamics of mean-motion resonances (MMRs) between pairs of coplanar planets and derive a new integrable Hamiltonian model for the planets’ resonant motion. The new model generalizes integrable Hamiltonians previously derived for first-order resonances to the case of higher-order resonances by exploiting a surprising near-symmetry of the full, non-integrable Hamiltonians of higher-order resonances. Whereas past works have frequently relied on truncated disturbing function expansions to derive integrable approximations to resonant motion, I show that no such truncated expansion is necessary to derive an integrable model. This enables the new model to accurately capture the dynamics of both first- and higher-order resonances for eccentricities up to orbit crossing. I demonstrate that predictions of the new integrable model agree well with numerical integrations of resonant planet pairs. Finally, I explore the secular evolution of resonant planets’ eccentricities. I show that the secular dynamics are governed by conservation of an angular-momentum-deficit-like quantity. I also demonstrate that secular frequencies depend on planets’ resonant libration amplitude and this generally gives rise to a secular resonance inside the MMR at large libration amplitudes. The integrable model derived in this work can serve as a framework for analyzing the dynamics of planetary MMRs in a wide variety of contexts.

Keywords: Orbital resonances