adsabs/SciX_UAT_keywords huggingface dataset:
On the Chemical Abundance of HR 8799 and the Planet c

Comparing chemical abundances of a planet and the host star reveals the origin and formation pathway of the planet. Stellar abundance is measured with high-resolution spectroscopy. Planet abundance, on the other hand, is usually inferred from low-resolution data. For directly imaged exoplanets, the data are available from a slew of high-contrast imaging/spectroscopy instruments. Here, we study the chemical abundance of HR 8799 and its planet c. We measure stellar abundance using LBT/PEPSI (R = 120,000) and archival HARPS data: stellar [C/H], [O/H], and C/O are 0.11 ± 0.12, 0.12 ± 0.14, and ${0.54}_{-0.09}^{+0.12}$ , all consistent with solar values. We conduct atmospheric retrieval using newly obtained Subaru/CHARIS data together with archival Gemini/GPI and Keck/OSIRIS data. We model the planet spectrum with petitRADTRANS and conduct retrieval using PyMultiNest. Retrieved planetary abundance can vary by ∼0.5 dex, from sub-stellar to stellar C and O abundances. The variation depends on whether strong priors are chosen to ensure a reasonable planet mass. Moreover, comparison with previous works also reveals inconsistency in abundance measurements. We discuss potential issues that can cause the inconsistency, e.g., systematics in individual data sets and different assumptions in the physics and chemistry in retrieval. We conclude that no robust retrieval can be obtained unless the issues are fully resolved.

Keywords: exoplanet atmospheric composition; planetary atmospheres; direct imaging; stellar atmospheres; coronagraphic imaging; exoplanet detection methods; chemically peculiar stars; peculiar variable stars; chemical abundances; abundance ratios; stellar abundances; chemically peculiar giant stars
The Search for a Counterpart to NuSTAR J053449+2126.0

(ATel #15171) have recently reported the discovery of an X-ray source, NuSTAR J053449+2126.0, during a calibration observation which took place on 2020 April 25. We scan the Zwicky Transient Facility alerts and archival photometry to determine the nature of the source. Palomar Gattini-IR is searched as well. We identify no obvious counterpart candidate. Follow-up X-ray and optical studies are needed to determine the true counterpart.

Keywords: x-ray astronomy; x-ray identification; time domain astronomy
Nondetection of Helium in the Upper Atmospheres of TRAPPIST-1b, e, and f

We obtained high-resolution spectra of the ultracool M-dwarf TRAPPIST-1 during the transit of its planet "b" using two high-dispersion near-infrared spectrographs, the Infrared Doppler (IRD) instrument on the Subaru 8.2m telescope, and the Habitable Zone Planet Finder (HPF) instrument on the 10 m Hobby-Eberly Telescope. These spectroscopic observations are complemented by a photometric transit observation for planet "b" using the APO/ARCTIC, which assisted us in capturing the correct transit times for our transit spectroscopy. Using the data obtained by the new IRD and HPF observations, as well as the prior transit observations of planets "b," "e" and "f" from IRD, we attempt to constrain the atmospheric escape of the planet using the He I triplet 10830 Å absorption line. We do not detect evidence for any primordial extended H-He atmospheres in all three planets. To limit any planet-related absorption, we place an upper limit on the equivalent widths of <7.754 mÅ for planet "b," <10.458 mÅ for planet "e," <4.143 mÅ for planet "f" at 95% confidence from the IRD data, and <3.467 mÅ for planet "b" at 95% confidence from HPF data. Using these limits along with a solar-like composition isothermal Parker wind model, we attempt to constrain the mass-loss rates for the three planets. For TRAPPIST-1b, our models exclude the highest possible energy-limited rate for a wind temperature <5000 K. This nondetection of extended atmospheres with low mean-molecular weights in all three planets aids in further constraining their atmospheric composition by steering the focus toward the search of high-molecular-weight species in their atmospheres. *Based on data collected at Subaru Telescope, operated by the National Astronomical Observatory of Japan, Hobby-Eberly Telescope operated by The University of Texas McDonald Observatory, and ARC 3.5m Telescope at Apache Point Observatory.

Keywords: exoplanets; transmission spectroscopy; exoplanet atmospheres
An Accreting, Anomalously Low-mass Black Hole at the Center of Low-mass Galaxy IC 750

We present a multiwavelength study of the active galactic nucleus in the nearby (D = 14.1 Mpc) low-mass galaxy IC 750, which has circumnuclear 22 GHz water maser emission. The masers trace a nearly edge-on, warped disk ∼0.2 pc in diameter, coincident with the compact nuclear X-ray source that lies at the base of the ∼kiloparsec-scale extended X-ray emission. The position-velocity structure of the maser emission indicates that the central black hole (BH) has a mass less than 1.4 × 105 M⊙. Keplerian rotation curves fitted to these data yield enclosed masses between 4.1 × 104 M⊙ and 1.4 × 105 M⊙, with a mode of 7.2 × 104 M⊙. Fitting the optical spectrum, we measure a nuclear stellar velocity dispersion ${\sigma }_{* }={110.7}_{-13.4}^{+12.1}$ km s-1. From near-infrared photometry, we fit a bulge mass of (7.3 ± 2.7) × 108 M⊙ and a stellar mass of 1.4 × 1010 M⊙. The mass upper limit of the intermediate-mass BH in IC 750 falls roughly two orders of magnitude below the MBH-σ* relation and roughly one order of magnitude below the MBH-MBulge and MBH-M* relations—larger than the relations' intrinsic scatters of 0.58 ± 0.09 dex, 0.69 dex, and 0.65 ± 0.09 dex, respectively. These offsets could be due to larger scatter at the low-mass end of these relations. Alternatively, BH growth is intrinsically inefficient in galaxies with low bulge and/or stellar masses, which causes the BHs to be undermassive relative to their hosts, as predicted by some galaxy evolution simulations.

Keywords: water masers; dwarf galaxies; active galactic nuclei
Target and Velocity Dependence of Charge Exchange X-Ray Emission at Solar Wind Velocities

Laboratory measurements of X-ray emissions following charge exchange (CX) between highly charged ions and neutrals are important to assess their diagnostic utility for the nonequilibrium astrophysical plasma environments, where hot flows meet cold gases. With a high-resolution X-ray quantum microcalorimeter detector, we report the CX-induced X-ray spectra and line ratios in Ne8+ on He and Kr collisions at solar wind velocities of 392, 554, 678, and 876 km s-1, respectively. The experimentally determined line ratios quantify the differences in CX state selectivity and the following X-ray emission between He and Kr at different collision velocities. This suggests that target and velocity dependence should be considered for accurately modeling astrophysical CX plasmas.

Keywords: atomic spectroscopy; atomic physics; collision physics; atomic data benchmarking; charge exchange recombination
TESS Timings of 31 Hot Jupiters with Ephemeris Uncertainties

A precise transit ephemeris serves as the premise for follow-up exoplanet observations. We compare TESS Object of Interest (TOI) transit timings of 262 hot Jupiters with the archival ephemeris and find 31 of them having TOI timing offsets, among which WASP-161b shows the most significant offset of -203.7 ± 4.1 minutes. The median value of these offsets is 17.8 minutes, equivalent to 3.6σ. We generate TESS timings in each sector for these 31 hot Jupiters, using a self-generated pipeline. The pipeline performs photometric measurements to TESS images and produces transit timings by fitting the light curves. We refine and update the previous ephemeris, based on these TESS timings (uncertainty ~1 minute) and a long timing baseline (~10 yr). Our refined ephemeris gives the transit timing at a median precision of 0.82 minutes until 2025 and 1.21 minutes until 2030. We regard the timing offsets to mainly originate from the underestimated ephemeris uncertainty. All the targets with timing offset larger than 10σ present earlier timings than the prediction, which cannot be due to underestimated ephemeris uncertainty, apsidal precision, or Rømer effect as those effects should be unsigned. For some particular targets, timing offsets are likely due to tidal dissipation. Our sample leads to the detection of period-decaying candidates of WASP-161b and XO-3b reported previously.

Keywords: exoplanet astronomy; exoplanet systems; transit photometry; transit timing variation method
EIGER. II. First Spectroscopic Characterization of the Young Stars and Ionized Gas Associated with Strong Hβ and [O III] Line Emission in Galaxies at z = 5-7 with JWST

We present emission-line measurements and physical interpretations for a sample of 117 [O III] emitting galaxies at z = 5.33-6.93, using the first deep JWST/NIRCam wide-field slitless spectroscopic observations. Our 9.7 hr integration is centered upon the z = 6.3 quasar J0100+2802-the first of six fields targeted by the EIGER survey-and covers λ = 3-4 μm. We detect 133 [O III] doublets, but close pairs motivated by their small scale clustering excess. The galaxies are characterized by a UV luminosity M UV ~ -19.6 (-17.7 to -22.3), stellar mass ~108 (106.8-10.1) M ⊙, Hβ and [O III]4960+5008 EWs ≈ 850 Å (up to 3000 Å), young ages, a highly excited interstellar medium, and low dust attenuations. These high EWs are very rare in the local universe, but we show they are ubiquitous at z ~ 6 based on the measured number densities. The stacked spectrum reveals Hγ and [O III]4364, which shows that the galaxies are typically dust- and metal-poor (E (B - V) = 0.1, $12+\mathrm{log}({\rm{O}}/{\rm{H}})=7.4$ ) with a high electron temperature (2 × 104 K) and a production efficiency of ionizing photons (ξ ion = 1025.3 Hz erg-1). We further show the existence of a strong mass-metallicity relation. The properties of the stars and gas in z ~ 6 galaxies conspire to maximize the [O III] output from galaxies, yielding an [O III] luminosity density at z ≈ 6 that is significantly higher than that at z ≈ 2. Thus, [O III] emission-line surveys with JWST prove a highly efficient method to trace the galaxy density in the Epoch of Reionization.

Keywords: high-redshift galaxies; galaxy formation; reionization; interstellar medium; chemical abundances
The Instantaneous Redshift Difference of Gravitationally Lensed Images: Theory and Observational Prospects

Due to the expansion of our universe, the redshift of distant objects changes with time. Although the amplitude of this redshift drift is small, it will be measurable with decade-long campaigns by the next generation of telescopes. Here we present an alternative view of the redshift drift which captures the expansion of the universe in single-epoch observations of the multiple images of gravitationally lensed sources. Considering a sufficiently massive lens, with an associated time delay of order decades, simultaneous photons arriving at a detector would have been emitted decades earlier in one image compared to another, leading to an instantaneous redshift difference between the images. We also investigated the peculiar velocity which may influence the redshift difference in observation. While still requiring the observational power of the next generation of telescopes and instruments, the advantage of such a single-epoch detection over other redshift drift measurements is that it will be less susceptible to systematic effects that result from requiring instrument stability over decade-long campaigns.

Keywords: strong gravitational lensing; cosmology
Two Episodes of a Filament Eruption from a Fan-spine Magnetic Configuration

In this paper, we present detailed observations of a filament eruption associated with a B6.0 flare, a jet-like coronal mass ejection (CME), and a type-III radio burst on 2013 March 2. The filament, which is located at the northwest edge of active region (AR) 11183, experienced a partial and then a full eruption. Each episode of the filament eruption produced a circular flare ribbon and a blowout jet, which is a mixture of hot and cool plasma that can be observed by the Solar Dynamics Observatory. Extrapolated coronal magnetic configuration using both the potential field source surface and the nonlinear force-free magnetic field models shows that the filament is embedded in a fan-spine magnetic topology. Considering the photospheric magnetic evolution, we suggest that the first episode of the filament eruption (partial eruption) is caused by the continuous photospheric magnetic flux cancellation below its western segment, while the eruption that follows results from the reduction of magnetic constraint above the filament in the aftermath of the first eruption episode and reconnection. Combining the observations with the extrapolated coronal magnetic configuration, we find that the event is an example that fits the null-point reconnection scenario. Our event is a result of null-point reconnection (interchange reconnection) between a closed filament magnetic field and the ambient open field at the edge of an AR, thus it has implications for the source of the slow speed solar wind and the source of the cold and dense plasma detected within.

Keywords: solar activity; solar filaments; solar coronal mass ejections; solar magnetic fields
Monte Carlo Simulation of Dust Particles in a Protoplanetary Disk: Crystalline to Amorphous Silicate Ratio in Comets

The observationally inferred crystalline abundance in silicates in comets, which should have been formed in the outer region of a protoplanetary disk, is relatively high (~10%-60%), although crystalline silicates would be formed by the annealing of amorphous precursors in the inner disk region. In order to quantitatively address this puzzle, we performed a Monte Carlo simulation of the advection/diffusion of silicate particles in a turbulent disk in a setting based on the pebble accretion model: pebbles consisting of many small amorphous silicates embedded in an icy mantle are formed in the outer disk region, silicate particles are released at the snow line, crystalline silicate particles are produced at the annealing line, silicate particles diffuse beyond the snow line, and they eventually stick to drifting pebbles to return to the snow line. In the simple case without sticking and with steady pebble flux, we show through the simulations and analytical arguments that the crystalline components in silicate materials beyond the snow line are robustly and uniformly ≃5%. On the other hand, in a more realistic case with sticking and with a decaying pebble flux, the crystalline abundance increases to ~20%-25%, depending on the ratio of the decay to diffusion timescales. This abundance is consistent with the observations. In this investigation, we assume a simple steady-accretion disk. The simulations coupled with the disk evolution are needed for a more detailed comparison with observed data.

Keywords: comets; protoplanetary disks; silicate grains
A Gaia Early DR3 Mock Stellar Catalog: Galactic Prior and Selection Function

We present a mock stellar catalog, matching in volume, depth and data model the content of the planned Gaia early data release 3 (Gaia EDR3). We have generated our catalog (GeDR3mock) using galaxia, a tool to sample stars from an underlying Milky Way (MW) model or from N-body data. We used an updated Besançon Galactic model together with the latest PARSEC stellar evolutionary tracks, now also including white dwarfs. We added the Magellanic clouds and realistic open clusters with internal rotation. We empirically modeled uncertainties based on Gaia DR2 (GDR2) and scaled them according to the longer baseline in Gaia EDR3. The apparent magnitudes were reddened according to a new selection of 3D extinction maps. To help with the Gaia selection function we provide all-sky magnitude limit maps in G and BP for a few relevant GDR2 subsets together with the routines to produce these maps for user-defined subsets. We supplement the catalog with photometry and extinctions in non-Gaia bands. The catalog is available in the Virtual Observatory (http://dc.g-vo.org/tableinfo/gedr3mock.main) and can be queried just like the actual Gaia EDR3 will be. We highlight a few capabilities of the Astronomy Data Query Language with educative catalog queries. We use the data extracted from those queries to compare GeDR3mock to GDR2, which emphasises the importance of adding observational noise to the mock data. Since the underlying truth, e.g., stellar parameters, is know in GeDR3mock, it can be used to construct priors as well as mock data tests for parameter estimation. All code, models and data used to produce GeDR3mock are linked and contained in galaxia_wrap (https://github.com/jan-rybizki/Galaxia_wrap), a python package, representing a fast galactic forward model, able to project MW models and N-body data into realistic Gaia observables.

Keywords: milky way galaxy; open star clusters; virtual observatories; stellar evolutionary models; interstellar dust extinction
SCExAO/MEC and CHARIS Discovery of a Low-mass, 6 au Separation Companion to HIP 109427 Using Stochastic Speckle Discrimination and High-contrast Spectroscopy

We report the direct imaging discovery of a low-mass companion to the nearby accelerating A star, HIP 109427, with the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument coupled with the Microwave Kinetic Inductance Detector Exoplanet Camera (MEC) and CHARIS integral field spectrograph. CHARIS data reduced with reference star point spread function (PSF) subtraction yield 1.1-2.4 μm spectra. MEC reveals the companion in Y and J band at a comparable signal-to-noise ratio using stochastic speckle discrimination, with no PSF subtraction techniques. Combined with complementary follow-up Lp photometry from Keck/NIRC2, the SCExAO data favors a spectral type, effective temperature, and luminosity of M4-M5.5, 3000-3200 K, and ${\mathrm{log}}_{10}(L/{L}_{\odot })=-{2.28}_{-0.04}^{+0.04}$ , respectively. Relative astrometry of HIP 109427 B from SCExAO/CHARIS and Keck/NIRC2, and complementary Gaia-Hipparcos absolute astrometry of the primary favor a semimajor axis of 6.55+3.0-0.48 au, an eccentricity of ${0.54}_{-0.15}^{+0.28}$ , an inclination of ${66.7}_{-14}^{+8.5}$ degrees, and a dynamical mass of ${0.280}_{-0.059}^{+0.18}$ M⊙. This work shows the potential for extreme AO systems to utilize speckle statistics in addition to widely used postprocessing methods to directly image faint companions to nearby stars near the telescope diffraction limit. * Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Keywords: direct imaging; astronomy data analysis; exoplanet detection methods; low mass stars
Two-step Dropouts of Radiation Belt Electron Phase Space Density Induced by a Magnetic Cloud Event

We report a two-step dropout event of radiation belt electron phase space density (PSD) induced by a typical magnetic cloud (MC) that drove an intense geomagnetic storm. The first and second steps of PSD dropout occurred, respectively, in the initial and main phases of the storm with a short-time partial recovery between the two dropouts. In this event, the initial phase after the sudden commencement lasted for near 21 hr, which gives an ideal opportunity to investigate the nature of the radiation belt electron dropout by isolating the main phase from any losses occurring during the initial phase. Detailed analysis shows that the first step of the dropout in the initial phase is likely associated with the magnetopause shadowing effect in combination with ultra-low frequency wave-induced outward transport caused by sustaining enhanced dynamic pressure activity before the MC. Comparably, the prolonged strong southward interplanetary magnetic field inside the MC that resulted in the storm main phase is supposed to play an important role in the second step of significant electron losses to the interplanetary space. Additionally, the partial recovery of electron PSD between the two steps of the dropout is possibly due to the acceleration processes via wave-particle interactions with whistler-mode chorus waves. Our study demonstrated that persistently enhanced solar wind dynamic pressure, which is frequently observed inside interplanetary coronal mass ejections and corotating interaction regions, can play an important role in modulating the radiation belt electron dynamics before the storm main phase driven by these solar wind disturbances.

Keywords: solar wind; solar-terrestrial interactions; astronomy data analysis
Probing the Subparsec Dust of a Supermassive Black Hole with the Tidal Disruption Event AT 2020mot

AT 2020mot is a typical UV/optical tidal disruption event (TDE) with no radio or X-ray signatures in a quiescent host. We find an i-band excess and rebrightening along the decline of the light curve which could be due to two consecutive dust echoes from the TDE. We model our observations following van Velzen et al. and find that the near-infrared light curve can be explained by concentric rings of thin dust within ∼0.1 pc of a ∼6 × 106 M ⊙ supermassive black hole (SMBH), among the smallest scales at which dust has been inferred near SMBHs. We find dust covering factors of order f c ≤ 2%, much lower than found for dusty tori of active galactic nuclei. These results highlight the potential of TDEs for uncovering the environments around black holes when including near-infrared observations in high-cadence transient studies.

Keywords: tidal disruption; ultraviolet transient sources; astrophysical dust processes
Phase Curves of Hot Neptune LTT 9779b Suggest a High-metallicity Atmosphere

Phase-curve measurements provide a global view of the composition, thermal structure, and dynamics of exoplanet atmospheres. Although most of the dozens of phase-curve measurements made to date are of large, massive hot Jupiters, there is considerable interest in probing the atmospheres of the smaller planets that are the more typical endproduct of the planet formation process. One such planet that is favorable for these studies is the ultrahot Neptune LTT 9779b, a rare denizen of the Neptune desert. A companion paper presents the planet&'s secondary eclipses and dayside thermal emission spectrum; in this work we describe the planet&'s optical and infrared phase curves, characterized using a combination of Spitzer and Transiting Exoplanet Survey Satellite (TESS) photometry. We detect LTT 9779b&'s thermal phase variations at 4.5 μm, finding a phase amplitude of 358 ± 106 ppm and no significant phase offset, with a longitude of peak emission occurring -10° ± 21° east of the substellar point. Combined with our secondary eclipse observations, these phase-curve measurements imply a 4.5 μm dayside brightness temperature of 1800 ± 120 K, a nightside brightness temperature of 700 ± 430 K (<1350 K at 2σ confidence), and a day-night brightness temperature contrast of 1110 ± 460 K. We compare our data to the predictions of 3D general circulation models calculated at multiple metallicity levels and to similar observations of hot Jupiters experiencing similar levels of stellar irradiation. Though not conclusive, our measurement of its small 4.5 μm phase offset, the relatively large amplitude of the phase variation, and the qualitative differences between our target&'s dayside emission spectrum and those of hot Jupiters of similar temperatures all suggest a supersolar atmospheric metallicity for LTT 9779b, as might be expected given its size and mass. Finally, we measure the planet&'s transits at both 3.6 μm and 4.5 μm, providing a refined ephemeris (P = 0.79207022 ± 0.00000069 days, T0 = 2458783.51636 ± 0.00027, BJDTDB) that will enable efficient scheduling of future observations to further characterize the atmosphere of this intriguing planet.

Keywords: exoplanet atmospheres