Sazuna/UAT_keywords huggingface dataset:
The Behavior of Bp Si Stars in the Far UV-Paper V: HD 187473. The analysis of five spectra of the B9 SiSrEu HD 187473 recorded by the Short Wavelength Prime camera on board the International Ultraviolet Explorer reveals large amplitude variations of the far ultraviolet spectral energy distribution over a time interval of about half the rotation period. In contrast, the level of the mid-UV flux does not vary between phases of FUV flux maximum and minimum which suggests that changes of the silicon continuous and line opacity play an important role in the variations. The iron-peak elements, chromium, manganese and iron probably also contribute to these variations.

Keywords: Bp stars, Chemically peculiar stars
Discovery of a Surprising Flux Event in White Dwarf HZ 4. HZ 4 is a DA3.4C White Dwarf (WD) and a commonly used photometric standard star. While analyzing its suitability as a calibrator, data from TESS revealed an increase in flux by 43.2%, seen only on Sector 43 observed in 2021 September and October. The event duration is 28.8 hr, and the light curve shape is approximately symmetric and consists of a flux increase preceded and followed by a flux decrease of 11.4%. If periodic, the period would be &gt;77 days. No other objects are observed in the Digital Sky Survey, Galaxy Evolution Explorer, or Wide-Field Infrared Explorer images within the TESS pixel in which HZ 4 resides. The event resembles the flux increases of long-lived WD pulsators, although HZ4 is not in the instability strip. There is no evidence of a binary companion, which suggests HZ4 is not a dwarf nova, nor photometric evidence of any circumstellar material.

Keywords: White dwarf stars, DA stars
Hidden Companions to Intermediate-mass Stars. III. Discovery of a 1.6M <SUB>⊙</SUB>, 1.3 au Companion to HIP 92041 = ϕ Sagittarii. B-type stars with masses up to about 8 M ⊙ are the progenitors of the heavier white dwarfs yet our knowledge about their multiplicity is still incomplete. The nearby subgiant HIP 92041 = ϕ Sagittarii has had claims of binarity in the past but they have all been refuted as spurious. In this report we show that ϕ Sgr is a binary after all based on a VLTI/GRAVITY interferometric observation. The companion has a K band flux ratio of 6% and a projected separation ρ = 17.7 mas ↔ 1.3 au. The inferred isochrone masses 3.5M ⊙ + 1.6M ⊙ make ϕ Sgr a potential progenitor for a white dwarf binary with a combined mass exceeding the Chandrasekhar limit. *Based on observations collected at the European Southern Observatory, Chile, Program ID 099.D-2020(A).

Keywords: Optical interferometry, Multiple stars, B stars
A New LBV Candidate in M33. The evolutionary relationships and mechanisms governing the behavior of the wide variety of luminous stars populating the upper H-R diagram are not well established. Luminous blue variables (LBVs) are particularly rare, with only a few dozen identified in the Milky Way and nearby galaxies. Since 2012, the Barber Observatory Luminous Stars Survey has monitored more than 100 luminous targets in M33, including M33C-4119 which has recently undergone photometric and spectroscopic changes consistent with an S Doradus eruption of an LBV.

Keywords: Massive stars, Luminous blue variable stars, Triangulum Galaxy
Light Curve and Period Change Analysis of KIC3347485. High precision photometry with the space-based Kepler telescope offers an opportunity to analyze the physical processes occurring in stars in detail. In this study, we examined the light curve of the Kepler binary system KIC 3347485, which is a semi-detached binary system. We calculated minima and maxima times of four years of Kepler observation of this system using our newly developed Python code. We did period change analysis (O - C) of this system, and we discuss the existence of a possible third or even fourth component.

Keywords: Eclipsing binary stars, Stellar photometry, Stellar evolution, Variable star period change
FUSE Spectroscopy of Two Luminosity Class II Giants. Analyses have been made of O VI λ1032 and C III λ977 line profiles in Far Ultraviolet Spectroscopic Explorer spectra of the luminosity class II giants HD 57623 and HD 160635. No conclusive evidence for an outflowing wind could be discerned.

Keywords: Stellar winds, Evolved stars, Giant stars
On the Recent Discovery of Coronal [Fe X]λ6374 Emission in the Low-metallicity Dwarf Galaxy SDSS J0944-0038. Coronal emission lines, especially the [Fe X]λ6374 line, are now being used as tracers for intermediate mass black holes (IMBHs) in low-mass galaxies. We show that the recent discovery of [Fe X]λ6374 emission in the metal-poor starburst SDSS J094401.87-003832.1 by Reefe et al. is, in fact, a misidentified line. The line interpreted as [Fe X]λ6374 is Si II λ6371. We caution that current and future campaigns hunting for IMBHs with the [Fe X]λ6374 line need to account for possible contamination by Si II λ6371 emission.

Keywords: Dwarf irregular galaxies, Emission line galaxies
New Jupiter and Saturn Satellites Reveal New Moon Dynamical Families. Tens of new moons around both Jupiter and Saturn have been announced on Minor Planet Electronic Circulars (MPECs) in late 2022 and early 2023. Jupiter now has 95 and Saturn 146 confirmed moons. Many smaller and fainter moons have also been detected at these planets but not yet confirmed through MPECs. These discoveries nearly complete the small moon population of Jupiter to about 2 km and Saturn to about 3 km and show new dynamical satellite families. The once lone Carpo is now joined by S/2018 J4, making it a group of two small prograde moons around Jupiter. The Inuit prograde family around Saturn appears to be 3 distinct groupings. S/2004 S24 seems to be a unique distant small Saturn prograde moon, as could be S/2006 S12 and S/2019 S6. S/2006 S20 might be the first found member of a compact Phoebe Saturn moon family.

Keywords: Saturnian satellites, Irregular satellites, Natural satellites (Solar system), Jovian satellites
Comment on "Observational Evidence for Cosmological Coupling of Black Holes and its Implications for an Astrophysical Source of Dark Energy". It was recently claimed that black holes can explain the accelerated expansion of the universe. Here I point out that this claim is based on a confusion about the principle of least action, undermining the link between black holes and dark energy.

Keywords: Black hole physics, Cosmological constant, Dark energy
New Active Asteroid (588045) 2007 FZ18. We present evidence that, on UT 2018 February 15, main-belt asteroid (588045) 2007 FZ18 displayed cometary activity in the form of two tails, one each in the anti-solar and anti-motion directions. Activity was first identified by volunteers of the NASA Partner program Active Asteroids, a Citizen Science program hosted on the Zooniverse platform, in an image acquired with the Dark Energy Camera on the Blanco 4 m telescope at the Cerro Tololo Inter-American Observatory in Chile. Notably, (588045) 2007 FZ18 is inbound toward perihelion, so telescope observations are timely to detect a possible second activity outburst.

Keywords: Comet tails, Main belt asteroids, Asteroids, Comae
Hidden Companions to Intermediate-mass Stars. IV. Uncovering a 1.1 M <SUB>⊙</SUB>, 1.3 au Companion in the Astrometric Binary HIP 77541. There are many Hipparcos/Gaia astrometric binaries for which the nature of the companion is not known. Optical/near-infrared inteferometry is arguably the most efficient method to unambiguously identify such companions. Here we report on a VLTI/GRAVITY observation in which we detected a companion to the nearby astrometric binary HIP 77541 with a K band flux ratio of 20% at a projected separation ρ = 18 mas ↔ 1.3 au. The resulting isochrone masses 2.0 + 1.1M ⊙ imply that HIP 77541 is a potential progenitor for a close white dwarf binary within a Hubble time. *Based on observations collected at the European Southern Observatory, Chile, Program ID 111.24UP.001.

Keywords: Optical interferometry, Multiple stars, Astrometric binary stars, A stars
The Behavior of Bp Si Stars in the far-UV-Paper VI: HD 215441. The analysis of spectra of the B9 Si star HD 215441 recorded by the SWP camera on board the International Ultraviolet Explorer reveals large amplitude variations of the far-ultraviolet spectral energy distribution over a time interval of about half the rotation period. In contrast, the level of the mid-UV flux does not vary between phases of FUV flux maximum and minimum which suggests that changes of the silicon continuous and line opacity play an important role in the variations. The optical brightness recorded by the Fine Error Sensor on board IUE is anticorrelated with the FUV flux, reflecting the redistribution of the FUV flux towards longer wavelengths.

Keywords: Bp stars, Chemically peculiar stars
Comparing the Photometric Calibration of DESI Imaging and Gaia Synthetic Photometry. The relative photometric calibration errors in the DESI Legacy Imaging Surveys (LS), which are used for DESI target selection, can leave imprints on the DESI target densities and bias the resulting cosmological measurements. We characterize the LS calibration systematics by comparing the LS stellar photometry with Gaia DR3 synthetic photometry. We find the stellar photometry of LS DR9 and Gaia has an RMS difference of 4.7, 3.7, 4.4 mmag in DECam grz bands, respectively, when averaged over an angular scale of $27^{\prime} $ . There are distinct spatial patterns in the photometric offset resembling the Gaia scan patterns (most notably in the synthesized g-band) which indicate systematics in the Gaia spectrophotometry, as well as honeycomb patterns due to LS calibration systematics. We also find large and smoothly varying photometric offsets at decl. &lt; -29.°25 in LS DR9 which are fixed in DR10.

Keywords: Spectrophotometry, Sky surveys, Photometry, Flux calibration
Cometary Activity on Quasi-Hilda Object 2018 CZ16. We present the discovery of activity originating from quasi-Hilda Object 2018 CZ16, a finding stemming from the Citizen Science project Active Asteroids. For 2018 CZ16 we identified a broad (~60°) but short (~5″) tail in archival Blanco 4 m data from Cerro Tololo Inter-American Observatory, Chile, (CTIO) Dark Energy Camera images from UT 2018 May 15, 17 and 18. Activity occurred 2 months prior to perihelion, consistent with sublimation-driven activity.

Keywords: Comet tails, Hilda group, Asteroids, Comae
A Recommendation to Retire VESPA for Exoplanet Validation. VESPA, the first open-source python package built to probabilistically validate exoplanet transit signals, has contributed to the validation of over a thousand exoplanets. However, since it is no longer maintained and has not been updated to account for the modern astronomy data landscape, we recommend retiring it in favor of the newer, actively maintained TRICERATOPS package.

Keywords: Astronomy software, Exoplanets
The Horizon of Future Intergalactic Travel. I show that non-relativistic objects traveling in intergalactic space at an initial peculiar velocity v will traverse in the future of the LCDM cosmological model a maximum comoving distance of ~(v/1.7H 0), irrespective of travel time, where H 0 is the Hubble constant. This follows from the future exponential growth of the scale factor. Hypervelocity stars escaping the halo of the Milky Way galaxy will not go beyond a few tens of comoving Mpc, even over the trillions of years that represent the lifetime of low-mass stars. To reach beyond the Virgo cluster of galaxies, requires an initial peculiar speed ≳3 × 103 km s-1, a hundred times faster than the chemical rockets launched to space so far.

Keywords: Extragalactic astronomy
Selecting z   8 Galaxies with JWST Photometry in CEERS. We present a method for selecting high-redshift galaxies from imaging and use this method to select a sample of z ~ 8 candidates from the Cosmic Evolution Early Release Science survey. In our selection process, we make use of the photometric redshift-fitting code EAZY to identify high-redshift galaxies based on their colors. Following previous works, we put constraints on the detection significance and quantities derived from the full photometric redshift probability distribution functions P(z). To further eliminate spurious sources, the spectral energy distribution (SED) and the images from both the James Webb Space Telescope and Hubble Space Telescope of candidate z ~ 8 galaxies are also examined. From the visual inspection of the SEDs and images, we identify a sample of 117 galaxy candidates at z ~ 8.

Keywords: High-redshift galaxies
Rotation Curve Measurement of Dark Matter Content of a z   0.5 Galaxy. Measurements of galaxy rotation curves provide direct measurements of the distribution of baryonic and dark matter in galaxies. Here, we present spectroscopic confirmation and one such rotation curve for a z = 0.5325 galaxy observed with Keck I/MOSFIRE as a filler target for the Web Epoch of Reionization Survey. The rotation curve was derived from Hα 6563 Å emission out to a galactocentric radius of approximately 24 kpc. The target's rotation curve is well fit by an arctangent curve, that when combined with broadbanned photometric constraints on the galaxy's stellar mass, predicts a dark matter fraction consistent with results from the literature for z ~ 0.5. We constrain the estimate for this galaxy's dark matter fraction to be 93%, out to a galactocentric radius of 30 kpc.

Keywords: Galaxy dark matter halos, Galaxy rotation curves, Disk galaxies
The FUSE Spectrum of HD 215441 (Babcock's Star). The analysis of the far-ultraviolet spectrum of the B9 Si HD 215441 recorded by the LWRS camera on board FUSE reveals a large deficiency of the flux when compared to the non-magnetic late B-type star HD 182308 of similar fundamental parameters. Most features can be identified using spectrum synthesis. The FUSE spectrum of HD 215441 contains mostly blends of low-excitation lines of Ti II, Mn II, Cr II, Fe II, a few lines of Ti III, Cr III and Fe III and interesting lines of C III, P II, S II and Cl I.

Keywords: Magnetic stars, Chemically peculiar stars
Constraints on the Bright Meyer Group Comet C/2023 F2 (SOHO). Comet C/2023 F2 (SOHO) was one of the brightest members of the poorly understood Meyer near-Sun comet group. Here we report our unsuccessful attempt to recover this comet from the ground using the Danish 1.54 m telescope. We observed the predicted position of the comet on 2023 April 4-5 UT when the comet was at 0.6 au and 36°-38° from the Sun, and searched an area that has 5%-10% likelihood to contain the comet down to R ~ 20. Despite the search being unsuccessful, we show that it is possible to reach reasonable depth at small solar elongation, and that wide-field meter-class telescopes are desirable for the recovery of these objects from the ground.

Keywords: Long period comets, Comets, Near-sun comets
A Photometric Hα Survey of the Open Cluster King 16. Photometric Hα observations of the young open cluster King 16 have been used to search for emission-line stars. Seven cluster members with enhanced Hα emission are identified, of which five are new discoveries. Three of these newly found objects have a near-infrared excess, which suggests they may be Herbig AeBe stars. Hα emission is also present in three field stars, of which two are new detections.

Keywords: Herbig Ae/Be stars, Be stars, Open star clusters
Hidden Companions to Intermediate-mass Stars. V. Discovery of a 1.6 M <SUB>⊙</SUB>, 0.3 au Companion to Marfik within the 48 au Visual Binary HIP 80883 = λ Ophiuchi. λ Ophiuchi is a nearby 48 au intermediate-mass visual binary with a hierarchical, 6400 au wide companion. We report on the discovery of a close companion to the primary star (Marfik) with a K band flux ratio of 33% at a projected separation ρ = 6.1 mas ↔ 0.32 au based on a VLTI/GRAVITY observation. Isochrone fitting yields masses M  Aa  = 2.39M ⊙, M  Ab  = 1.62M ⊙ and M  B  = 1.82M ⊙. λ Oph therefore joins a growing number of intermediate-mass binaries with 10-60 au separation in which the primary is found to be a close binary and which suggest that many white dwarfs with a main sequence companion at such separations (such as Sirius B) ultimately descended from merger products. In fact, λ Oph is a potential progenitor for a system resembling Sirius. *Based on observations collected at the European Southern Observatory, Chile, Program ID 111.24UP.003.

Keywords: Optical interferometry, Multiple stars, A stars
Clarifying the Optical Thin-lens Equations of Gravitational Self-lensing. We exploit an analogy between gravitational lenses and optical lenses to determine the Gaussian form of the optical thin-lens equation of gravitational self-lensing (this is not the deflection-angle equation which is also called the "ray-tracing equation"). As in magnifying glasses, this Gaussian form determines the location of the virtual image in front of the lens and behind the source. Some confusion exists in the literature because a similar-looking equation of totally different substance is often written down, creating the false impression that this may be the equivalent optical lens equation. Although dimensionally correct and quite useful, this imitating form is misleading, as it masks a compound rate that should instead have always been visible. We clarify all related concepts, so that the readers will save themselves the unpleasant experience of reinterpreting/reclassifying the various self-lensing equations, including the new optical forms derived herein.

Keywords: Gravitational lensing, Black hole physics, Compact binary stars, Gravitational microlensing
OH Emission Among Mira Variables in Color-Magnitude and Period-Magnitude Diagrams. Infrared absolute-magnitude versus color diagrams have been derived for long-period Mira variables with and without OH-maser emission through the use of Gaia DR3 parallaxes and two samples of stars drawn from the literature. The OH-emitting Miras are mostly consistent with (J - K  s ) &gt; 1.4, an average absolute K  s  magnitude of around -7.6, and pulsation periods greater than 316 days.

Keywords: Mira variable stars, Me stars, Pulsating variable stars, Stellar mass loss
The Behavior of Bp He-weak Stars in the Far UV-Paper VI: HD 21699. The analysis of spectra of the B8 He-weak Si star HD 21699 recorded by the SWP camera on board the International Ultraviolet Explorer in 1987 reveals large amplitude variations of the far-ultraviolet spectral energy distribution over a time interval of about four days in 1987 October. In contrast, the level of the mid-UV flux did not vary between phases of FUV flux maximum and minimum which suggests that changes of the silicon continuous and line opacity play an important role in the variations. The lines of C IV doublet near 1550 Å are stronger and have an extended blue wing at phase of far-UV maximum. The optical brightness recorded by the Fine Error Sensor on board IUE is probably anticorrelated with the FUV flux, reflecting the redistribution of the FUV flux toward longer wavelengths.

Keywords: Helium-weak stars, Chemically peculiar stars
GRB 210619B: First Gamma-Ray Burst Detection by the Novel Polarimeter MOPTOP. GRB 210619B was a bright long gamma-ray burst (GRB) which was optically followed up by the novel polarimeter MOPTOP on the Liverpool Telescope. This was the first GRB detection by the instrument since it began science observations. MOPTOP started observing the GRB 1388 s after the Swift Burst Alert Telescope trigger. The R band light-curve decays following a broken power law with a break time of 2948 s after the trigger. The decay index values are α 1 = 0.84 ± 0.03 (pre-break) and α 2 = 0.54 ± 0.02 (post-break), indicating that the observation was most probably during the forward shock-dominated phase. We find a polarization upper limit of ~7%. In the forward shock we expect the polarization to mostly come from dust in the local ambient medium which only produces low degrees of polarization. Hence our non-detection of polarization is as expected for this particular burst.

Keywords: Gamma-ray bursts, Polarimetry, Photometry
Comment on the Feasibility of Carbon Burning in Betelgeuse. The recent pre-print (version published to arxiv on 2023 June 3rd) by Saio et al. argues that the supergiant Betelgeuse is already undergoing carbon burning, based the assumption that all of its light variations are caused by radial pulsations. However, the angular diameter measurements of the star are in conflict with the stellar radius required by their models, as we show in this note. We discuss the feasibility that the Great Dimming was caused by constructive mode interference using long-term brightness measurements and comment on differences in modeling frameworks adopted in Saio et al. versus Joyce et al.

Keywords: Pulsating variable stars
Real-time Technosignature Strategies with SN 2023ixf. Several technosignature techniques focus on historic events such as SN 1987A as the basis to search for coordinated signal broadcasts from extraterrestrial agents. The recently discovered SN 2023ixf in the spiral galaxy M101 is the nearest Type II supernova in over a decade, and will serve as an important benchmark event. Here we review the potential for SN 2023ixf to advance ongoing techonsignature searches, particularly signal-synchronization techniques such as the "SETI Ellipsoid" that identifies over time stars that could transmit signals after observing a supernovae event. We find that more than 100 stars within 100 pc are already close to intersecting this SETI Ellipsoid, providing numerous targets for real-time monitoring within ~3° of SN 2023ixf. We are commencing a radio technosignature monitoring campaign of these targets with the Allen Telescope Array and the Green Bank Telescope.

Keywords: Search for extraterrestrial intelligence, Technosignatures, Core-collapse supernovae, Type II supernovae
Improving MCMC Convergence for Joint Astrometry and Radial Velocity Orbit-fits Through Reparameterization. The exoplanet orbit-fitting software package orbitize! was initially designed to fit the orbits of directly imaged planets with relative astrometric measurements using a Markov Chain Monte Carlo (MCMC) algorithm. Since the publication of orbitize! v1.0, the ability to jointly fit radial velocities and astrometry has been incorporated. We first implemented a Basis class into orbitize! that enables users to add and fit in various orbit parameterizations. We then introduced a radial velocity-focused parameterization of the Keplerian orbital elements for the joint radial velocity and astrometry fits. We compared MCMC convergence speeds of the new radial velocity-focused basis to the original orbitize! standard basis for the system HD 190771, which has full orbital coverage in radial velocity data. We found a 16% faster convergence in time with the radial velocity-focused basis. We encourage users to consider using this basis when doing joint radial velocity and astrometry fits.

Keywords: Spectroscopic binary stars, Orbits, Visual binary stars, Exoplanet dynamics
Photometric Monitoring of the ZZ Ceti Star PG 1541+651. The Kepler and K2 missions discovered multiple ZZ Ceti white dwarf pulsators that exhibit recurrent outbursts. These outbursting white dwarfs are near the red edge of the ZZ Ceti instability strip, suggesting that the phenomenon is physically related to the cessation of pulsations. We present multi-day ground-based monitoring of the poorly studied red-edge ZZ Ceti pulsator PG 1541+651. We do not detect any outbursts in our data. We do find that this pulsator has a very rich and time-variable spectrum of modes in its periodogram. The white dwarf lies in the northern continuous viewing zone of TESS; therefore, it has extensive archival light curves ripe for a detailed asteroseismic analysis of this star.

Keywords: White dwarf stars, Multi-periodic variable stars, ZZ Ceti stars