Sazuna/UAT_keywords huggingface dataset:
Detecting Isolated Stellar-mass Black Holes with the Roman Telescope. Isolated stellar-mass black holes (ISMBHs) are potentially discernible through microlensing observations, because they are expected to be long-duration microlensing events. In this work, we study the detection and characterization of ISMBHs using Roman observations. We simulate a large ensemble of such events, as they will be seen by Roman, and estimate the errors in the physical parameters of the lens objects, including their masses, distances, and proper motions, by calculating Fisher and covariance matrices. Since the ~2.3 yr time gap between Roman's first three observing seasons and its latter three seasons may lower the efficiency of its realization of microlensing events and characterization of ISMBHs, we additionally consider a scenario where we add a small number of additional observations-1 hr of observations, every 10 days, when the Bulge is observable during the large time gap-which is equivalent to a total of an additional day of observations with the Roman telescope. These extra observations increase Roman's efficiency in terms of characterizing ISMBHs by ~1%-2%, and, more importantly, they improve the robustness of the results, by avoiding possible degenerate solutions. By considering uniform and power-law mass functions ( ${dN}/{dM}\propto {M}^{-\alpha }$ , α = 2, 1, 0.5) for ISMBHs in the range of [2, 50]M ⊙, we conclude that the Roman telescope will determine the physical parameters of the lenses (the mass, distance, and relative lens-source angular velocity) within &lt;5% uncertainty, with efficiencies of 21% and 16%-18%, respectively. By considering these mass functions, we expect that during its mission the Roman telescope will detect and characterize 3-4, 15-17, and 22-24 ISMBHs through astrometric microlensing, with the relative errors for all physical parameters being less than 1%, 5%, and 10%, respectively. Microlensing events due to ISMBHs with masses ≃10-25M ⊙ that are located close to the observer, with D l ≲ 0.5D s, while the source is inside the Galactic disk, can be characterized with the fewest errors.

Keywords: Gravitational microlensing, Space telescopes, Stellar mass black holes, Computational methods
A Reanalysis of the Composition of K2-106b: An Ultra-short-period Super-Mercury Candidate. We present a reanalysis of the K2-106 transiting planetary system, with a focus on the composition of K2-106b, an ultra-short-period, super-Mercury candidate. We globally model existing photometric and radial velocity data and derive a planetary mass and radius for K2-106b of M  p  = 8.53 ± 1.02 M ⊕ and ${R}_{p}={1.71}_{-0.057}^{+0.069}\,{R}_{\oplus }$ , which leads to a density of ${\rho }_{p}={9.4}_{-1.5}^{+1.6}$ g cm-3, a significantly lower value than previously reported in the literature. We use planet interior models that assume a two-layer planet comprised of a liquid, pure Fe core and an iron-free, MgSiO3 mantle, and we determine that the range of the core mass fractions are consistent with the observed mass and radius. We use existing high-resolution spectra of the host star to derive the Fe/Mg/Si abundances ([Fe/H] = -0.03 ± 0.01, [Mg/H] = 0.04 ± 0.02, [Si/H] = 0.03 ± 0.06) to infer the composition of K2-106b. We find that K2-106b has a density and core mass fraction ( ${44}_{-15}^{+12} \% $ ) consistent with that of Earth (CMF⊕ = 32%). Furthermore, its composition is consistent with what is expected, assuming that it reflects the relative refractory abundances of its host star. K2-106b is therefore unlikely to be a super-Mercury, as has been suggested in previous literature.

Keywords: Planetary interior, Exoplanet systems
Impact of Correlated Noise on the Mass Precision of Earth-analog Planets in Radial Velocity Surveys. Characterizing the masses and orbits of near-Earth-mass planets is crucial for interpreting observations from future direct imaging missions (e.g., HabEx, LUVOIR). Therefore, the Exoplanet Science Strategy report recommended further research so future extremely precise radial velocity surveys could contribute to the discovery and/or characterization of near-Earth-mass planets in the habitable zones of nearby stars prior to the launch of these future imaging missions. Newman et al. (2023) simulated such 10 yr surveys under various telescope architectures, demonstrating they can precisely measure the masses of potentially habitable Earth-mass planets in the absence of stellar variability. Here, we investigate the effect of stellar variability on the signal-to-noise ratio (S/N) of the planet mass measurements in these simulations. We find that correlated noise due to active regions has the largest effect on the observed mass S/N, reducing the S/N by a factor of ~5.5 relative to the no-variability scenario; granulation reduces by a factor of ~3, while p-mode oscillations has little impact on the proposed survey strategies. We show that in the presence of correlated noise, 5 cm s-1 instrumental precision offers little improvement over 10 cm s-1 precision, highlighting the need to mitigate astrophysical variability. With our noise models, extending the survey to 15 yr doubles the number of Earth-analogs with mass S/N &gt; 10, and reaching this threshold for any Earth-analog orbiting a star &gt;0.76 M ⊙ in a 10 yr survey would require an increase in the number of observations per star from that in Newman et al. (2023).

Keywords: Stellar oscillations, Time series analysis, Radial velocity, Stellar activity, Exoplanet detection methods, Stellar granulation
Absolute Calibration. III. Improved Absolute Calibration for the Visible through the Mid-infrared. We propose Sirius as an improved zero-point-defining star and calibrate its spectrum to an accuracy of ~0.6% in both the visible and infrared. This result is based on a newly derived independent calibration in the visible of similar accuracy to the previous standard one, with which it is combined. We use a large variety of approaches in the infrared to reach about three times smaller error than for previous absolute calibrations. The results in the two wavelength regimes are in agreement, providing a consistent link from the visible throughout the near- and mid-infrared. The Sirius-based zero-point at 5557.5 Å (in vacuum) is 13.436 ± 0.081 × 10-12 W cm-2 μm-1, based on the improved value for Vega of 3.473 ± 0.018 × 10-12 W cm-2 μm-1 and the measured magnitude difference between the two stars. At 2.1603 μm, the zero-point is 4.225 ± 0.025 × 10-14 W cm-2 μm-1 taking Sirius at a magnitude of -1.395. A jackknife analysis indicates that there are no serious systematic errors in these results. We consider selection of secondary standards that can extend the calibration over the sky. Despite more than a century in this role, normal A-stars are not suitable, although Am and Ap stars may be. G-stars older than ~1 Gyr are good candidates if accurate temperatures can be measured. White dwarfs are suitable from the visible through the near-infrared, but their properties are unexplored at the necessary level at the longer infrared wavelengths, and for most facilities they are too faint there. Finally, as a further test of the calibration, we demonstrate an upgraded infrared flux method to determine accurate stellar diameters from K-band photometry.

Keywords: Calibration, Infrared photometry
Metal Mixing in the r-process Enhanced Ultrafaint Dwarf Galaxy Reticulum II. The ultrafaint dwarf galaxy Reticulum II was enriched by a single rare and prolific r-process event. The r-process content of Reticulum II thus provides a unique opportunity to study metal mixing in a relic first galaxy. Using multi-object high-resolution spectroscopy with VLT/GIRAFFE and Magellan/M2FS, we identify 32 clear spectroscopic member stars and measure abundances of Mg, Ca, Fe, and Ba where possible. We find ${72}_{-12}^{+10} \% $ of the stars are r-process-enhanced, with a mean $\left\langle [\mathrm{Ba}{\rm{/}}{\rm{H}}]\right\rangle =-1.68\,\pm \,0.07$ and unresolved intrinsic dispersion σ [Ba/H]&lt;0.20. The homogeneous r-process abundances imply that Ret II's metals are well mixed by the time the r-enhanced stars form, which simulations have shown requires at least 100 Myr of metal mixing in between bursts of star formation to homogenize. This is the first direct evidence of bursty star formation in an ultrafaint dwarf galaxy. The homogeneous dilution prefers a prompt and high-yield r-process site, such as collapsar disk winds or prompt neutron star mergers. We also find evidence from [Ba/H] and [Mg/Ca] that the r-enhanced stars in Ret II formed in the absence of substantial pristine gas accretion, perhaps indicating that ≈70% of Ret II stars formed after reionization. *This paper includes data gathered with the 6.5 m Magellan Telescopes, located at Las Campanas Observatory, Chile.

Keywords: Local Group, Galaxy chemical evolution, R-process, Dwarf galaxies, Chemical abundances
Multiepoch Detections of the Extended Atmosphere and Transmission Spectra of KELT-9b with a 1.5 m Telescope. Irradiated Jovian atmospheres are complex and dynamic and can undergo temporal variations due to the close proximity of their parent stars. Of the Jovian planets that have been cataloged to date, KELT-9b is the hottest gas giant known, with an equilibrium temperature of 4050 K. We probe the temporal variability of transmission spectroscopic signatures from KELT-9b via a set of archival multiyear ground-based transit observations, performed with the TRES facility on the 1.5 m reflector at the Fred Lawrence Whipple Observatory. Our observations confirm past detections of Fe I, Fe II, and Mg I over multiple epochs, in addition to excess absorption at Hα, which is an indicator for ongoing mass loss. From our multiyear data set, the Hα light curve consistently deviates from a standard transit and follows a "W" shape that is deeper near ingress and egress and shallower midtransit. To search for and quantify any seasonal variations that may be present, we parameterize a "cometary tail" model to fit for the Hα transit. We find no detectable variations between the different observed epochs. Though a "cometary tail" describes the Hα flux variations well, we note that such a scenario requires a high density of neutral hydrogen in the n = 2 excited state far beyond the planetary atmosphere. Other scenarios, such as center-to-limb variations larger than that expected from 1D atmosphere models, may also contribute to the observed Hα transit shape. These multiepoch observations highlight the capabilities of small telescopes to provide temporal monitoring of the dynamics of exoplanet atmospheres.

Keywords: Exoplanet atmospheric composition , Hot Jupiters, Exoplanets, Exoplanet atmospheric variability, Exoplanet evolution
Relation between Long-term Activity and Luminosity of the Pre- and Post-novae CT Ser and V446 Her. We show a relation of the pre- and post-nova activity of CT Ser (nova 1948) and V446 Her (nova 1960), known to have remarkably similar orbital periods P orb. We use both photographic and CCD photometric observations. Post-nova CT Ser shows a nova-like high-state activity with only a slight decrease of absolute magnitude M opt. In the interpretation, its M opt is above the region of the thermal-viscous instability (TVI) regime, so the disk is ionized out to its outer rim, similarly to before its classical nova (CN) outburst. On the contrary, V446 Her started its CN outburst from the TVI regime. Extensive changes in activity type in years after CN outburst were observed in V446 Her. The features consistent with the dwarf-nova outbursts appeared at most three decades after the end of the CN outburst. It suggests that its disk transitioned into the TVI region in that it was before its CN outburst. The pre-nova and post-nova states of activity did not change significantly for a given system, except for several decades after the CN outburst. Even pre-novae and post-novae with mutually similar P orb, hence secondary star (donor) spectral types and dimensions and disk radii, can show largely discrepant M opt and disk states in the similar epochs (several decades) surrounding the CN outburst.

Keywords: Accretion, Dwarf novae, Astrophotography, Cataclysmic variable stars, Classical novae
Systematic KMTNet Planetary Anomaly Search. VII. Complete Sample of q &lt; 10<SUP>-4</SUP> Planets from the First 4 yr Survey. We present the analysis of seven microlensing planetary events with planet/host mass ratios q &lt; 10-4: KMT-2017-BLG-1194, KMT-2017-BLG-0428, KMT-2019-BLG-1806, KMT-2017-BLG-1003, KMT-2019-BLG-1367, OGLE-2017-BLG-1806, and KMT-2016-BLG-1105. They were identified by applying the Korea Microlensing Telescope Network (KMTNet) AnomalyFinder algorithm to 2016-2019 KMTNet events. A Bayesian analysis indicates that all the lens systems consist of a cold super-Earth orbiting an M or K dwarf. Together with 17 previously published and three that will be published elsewhere, AnomalyFinder has found a total of 27 planets that have solutions with q &lt; 10-4 from 2016-2019 KMTNet events, which lays the foundation for the first statistical analysis of the planetary mass-ratio function based on KMTNet data. By reviewing the 27 planets, we find that the missing planetary caustics problem in the KMTNet planetary sample has been solved by AnomalyFinder. We also find a desert of high-magnification planetary signals (A ≳ 65), and a follow-up project for KMTNet high-magnification events could detect at least two more q &lt; 10-4 planets per year and form an independent statistical sample.

Keywords: Gravitational microlensing exoplanet detection
Emergent Spectral Fluxes of Hot Jupiters: An Abrupt Rise in Dayside Brightness Temperature Under Strong Irradiation. We study the emergent spectral fluxes of transiting hot Jupiters, using secondary eclipses from Spitzer. To achieve a large and uniform sample, we have reanalyzed all secondary eclipses for all hot Jupiters observed by Spitzer at 3.6 and/or 4.5 μm. Our sample comprises 457 eclipses of 122 planets, including eclipses of 13 planets not previously published. We use these eclipse depths to calculate the spectral fluxes emergent from the exoplanetary atmospheres, and thereby infer the temperatures and spectral properties of hot Jupiters. We find that an abrupt rise in brightness temperature, similar to a phase change, occurs on the dayside atmospheres of the population at an equilibrium temperature between 1714 and 1818 K (99% confidence limits). The amplitude of the rise is 291 ± 49 K, and two viable causes are the onset of magnetic drag that inhibits longitudinal heat redistribution, and/or the rapid dissipation of dayside clouds. We also study hot Jupiter spectral properties with respect to metallicity and temperature inversions. Models exhibiting 4.5 μm emission from temperature inversions reproduce our fluxes statistically for the hottest planets, but the transition to emission is gradual, not abrupt. The Spitzer fluxes are sensitive to metallicity for planets cooler than ~1200 K, and most of the hot Jupiter population falls between model tracks having solar to 30× solar metallicity.

Keywords: Exoplanet astronomy, Hot Jupiters, Exoplanet atmospheres, Infrared astronomy
A uvbyCaHβ CCD Analysis of the Open Cluster Standard, M67, and Its Relation to NGC 752. Precision CCD uvbyCaHβ photometry is presented of the old cluster, M67, covering one square degree with typical internal precision at the 0.005-0.020 mag level to V ~ 17. The photometry is calibrated using standards over a wide range in luminosity and temperature from NGC 752 and zeroed to the standard system via published photoelectric observations. Relative to NGC 752, differential offsets in reddening and metallicity are derived using astrometric members, supplemented by radial velocity information. From single-star members, offsets in the sense (M67-NGC 752) are δ E(b - y) = -0.005 ± 0.001 (sem) mag from 327 F/G dwarfs and δ[Fe/H] = 0.062 ± 0.006 (sem) dex from the combined m 1 and hk indices of 249 F dwarfs, leading to E(b - y) = 0.021 ± 0.004 (sem) and [Fe/H]M67 = +0.030 ± 0.016 (sem) assuming [Fe/H]Hyades = +0.12. With probable binaries eliminated using c 1, (b - y) indices, 83 members with (π/σ  π ) &gt; 50 generate (m - M)0 = 8.220 ± 0.005 (sem) for NGC 752 and an isochronal age of 1.45 ± 0.05 Gyr. Using the same parallax restriction for 312 stars, M67 has (m - M) = 9.77 ± 0.02 (sem), leading to an age tied solely to the luminosity of the subgiant branch of 3.70 ± 0.03 Gyr. The turnoff color spread implies ±0.1 Gyr, but the turnoff morphology defines a younger age/higher mass for the stars, consistent with recent binary analysis and broadband photometry indicating possible missing physics in the isochrones. Anomalous stars positioned blueward of the turnoff are discussed.

Keywords: Open star clusters, Strömgren photometry
The Molecular Clouds in a Section of the Third Galactic Quadrant: Cloud Catalog. We present results of cloud catalogs of 12CO, 13CO, and C18O (J = 1-0) in a section of the third Galactic quadrant over (195° &lt; l &lt; 220°, ∣b∣ &lt; 5°) from the Milky Way Imaging Scroll Painting project. The data were acquired with the PMO 13.7 m millimeter telescope with ~50″angular resolution. We construct three molecular cloud catalogs containing information of 12CO, 13CO, and C18O from the position-position-velocity (PPV) data cubes. The 12CO cloud catalog contains 7069 samples identified based on the DBSCAN algorithm. We develop a new algorithm, the stacking bump algorithm, for identifying 13CO and C18O emission by searching for weak signals in the original spectra of 13CO and C18O within the boundary in PPV space defined by the 12CO cloud. Above the 2σ threshold level, we identified 1197 clouds having 13CO emission and 32 clouds having C18O emission. We test the stacking bump algorithm in the noise-only datacube and find that the 2σ threshold can effectively avoid the possibility of false detection generated by noise. The results proved that the new algorithm has high accuracy and completeness. Statistics of peak intensity, projected angular area, line width, and flux of the clouds show that the power-law indices obtained from different isotopic lines are close to each other.

Keywords: Molecular gas, Molecular clouds
A Lack of Variability between Repeated Spitzer Phase Curves of WASP-43b. Though the global atmospheres of hot Jupiters have been extensively studied using phase curve observations, the level of time variability in these data is not well constrained. To investigate possible time variability in a planetary phase curve, we observed two full-orbit phase curves of the hot Jupiter WASP-43b at 4.5 μm using the Spitzer Space Telescope, and reanalyzed a previous 4.5 μm phase curve from Stevenson et al. We find no significant time variability between these three phase curves, which span timescales of weeks to years. The three observations are best fit by a single phase curve with an eclipse depth of 3907 ± 85 ppm, a dayside-integrated brightness temperature of 1479 ± 13 K, a nightside integrated brightness temperature of 755 ± 46 K, and an eastward-shifted peak of 10.°4 ± 1.°8. To model our observations, we performed 3D general circulation model simulations of WASP-43b with simple cloud models of various vertical extents. In comparing these simulations to our observations, we find that WASP-43b likely has a cloudy nightside that transitions to a relatively cloud-free dayside. We estimate that any change in WASP-43b's vertical cloud thickness of more than three pressure scale heights is inconsistent with our observed upper limit on variation. These observations, therefore, indicate that WASP-43b's clouds are stable in their vertical and spatial extent over timescales up to several years. These results strongly suggest that atmospheric properties derived from previous, single Spitzer phase curve observations of hot Jupiters likely show us the equilibrium properties of these atmospheres.

Keywords: Observational astronomy, Hot Jupiters, Exoplanets, Exoplanet atmospheric variability, Exoplanet atmospheres
Astrophysical Properties of 600 Bona Fide Single Stars in the Hyades Open Cluster. The determination of the astrophysical properties of stars remains challenging and frequently relies on the application of stellar models. Stellar sequences in nearby open clusters provide some of the best means to test and calibrate stellar evolutionary models and isochrones and to use these models to assign astrophysical properties consistently to a large sample of stars. We aim at updating the single-star sequence of the members of the Hyades cluster, identifying the best-fitting isochrones, and determining the astrophysical properties of the stars. The Gaia Catalog of Nearby Stars provides a comprehensive sample of high-probability members of the Hyades cluster. We apply a multistep method to flag photometric outliers and to identify bona fide single stars and likely binary and multiple systems. The single stars define a tight sequence, which in the mass range 0.12-2.2 M ⊙ is well fitted by PARSEC isochrones for a supersolar metallicity of [M/H] = +0.18 ± 0.03 and an age of 775 ± 25 Myr. The isochrones enable us to assign mass, effective temperature, luminosity, and surface gravity to each of the 600 bona fide single main-sequence stars. The observed sequence validates the PARSEC isochrones. The derived stellar properties can serve as benchmarks for atmospheric and evolutionary models and for all-sky catalogs of stellar astrophysical properties. The stellar properties are also relevant for studies of exoplanet properties among Hyades exoplanet hosts.

Keywords: Stellar luminosities, Stellar properties, Stellar ages, Stellar abundances, Stellar effective temperatures, Stellar dynamics, Young star clusters, Stellar colors, Stellar types, Stellar masses, Open star clusters, Stellar evolution
The Origin of the Nuclear Star-forming Ring in NGC 3182. We investigate the stellar and ionized gas kinematics, and stellar populations of NGC 3182 galaxy using integral field spectrograph data from the Calar Alto Legacy Integral Field Area survey. We try to clarify the nature of the ring structure in NGC 3182. We find a negative stellar age gradient out to the ring, while [α/Fe] considerably enhanced in the ring. The stellar metallicity shows a smooth negative gradient. From the line-ratio diagnostic diagrams, we confirm that NGC 3182 is a Seyfert galaxy from emission-line flux ratio, while the gas in the inner ring is ionized mostly by young stars. However, any obvious feature of outflows is not found in its gas kinematics. In the ring, star formation seems to have recently occurred and the gas metallicity is slightly enhanced compared to the center. From our results, we conclude that star formation has occurred in the circumnuclear region within a short period and this may result from a positive feedback by active galactic nucleus radiation pressure.

Keywords: Galaxy abundances, Galaxy stellar content, Galaxy chemical evolution