adsabs/SciX_UAT_keywords huggingface dataset:
High-resolution Linear Spectropolarimetry of Red Supergiant VY CMa: Identification of Atomic and Molecular Features

We present a high-resolution optical spectropolarimetric observation of the red supergiant VY CMa. The optical spectrum of VY CMa contains numerous emission features that are mainly due to molecular bands of TiO, ScO, and VO. In addition, emission lines of Ba II, Ca I, Na I, K I, and Rb I are identified in the spectrum. Our observation shows that all the molecular bands exhibit a very large and abrupt linear polarization reduction, i.e., depolarization, across the band heads of up to 10% or higher with respect to the continuum polarization level. The high-resolution observations demonstrate clearly that the molecular band heads are associated with the largest depolarization. Using this property together with a simulated emission spectrum of TiO we are able to identify most of the broad emission features in the optical spectrum of VY CMa as the TiO band heads in emission. Our observations also reveal a previously unknown phenomenon that the atomic lines either in emission or absoprtion also exhibit large depolarization across the line profile, with the K I doublet showing almost complete depolarization. The observed polarization pattern is very similar among either absoprtion or emission lines, even though the spectral lines belong to different atomic species. Together with recent high spectral resolution observations, we discuss the origin of this phenomenon and suggest that the observed large depolarization across molecular bands and atomic lines is due to absorption and scattering in the complex circumstellar environment of VY CMa, especially in the dense dusty clumps located almost on the plane of the sky.

Keywords: a supergiant stars; starlight polarization
Predicting Asteroid Material Properties from a DART-like Kinetic Impact

NASA's Double Asteroid Redirection Test (DART) mission is the first full-scale test of the kinetic impactor method for asteroid deflection, in which a spacecraft intentionally impacts an asteroid to change its trajectory. DART represents an important first step for planetary defense technology demonstration, providing a realistic assessment of the effectiveness of the kinetic impact approach on a near-Earth asteroid. The momentum imparted to the asteroid is transferred from the impacting spacecraft and enhanced by the momentum of material ejected from the impact site. However, the magnitude of the ejecta contribution is dependent on the material properties of the target. These properties, such as strength and shear modulus, are unknown for the DART target asteroid, Dimorphos, as well as most asteroids since such properties are difficult to characterize remotely. This study examines how hydrocode simulations can be used to estimate material properties from information available post-impact, specifically the asteroid size and shape, the velocity and properties of the impacting spacecraft, and the final velocity change imparted to the asteroid. Across >300 three-dimensional simulations varying seven material parameters describing the asteroid, we found many combinations of properties could reproduce a particular asteroid velocity. Additional observations, such as asteroid mass or crater size, are required to further constrain properties like asteroid strength or outcomes like the momentum enhancement provided by impact ejecta. Our results demonstrate the vital importance of having as much knowledge as possible prior to an impact mission, with key material parameters being the asteroid's mass, porosity, strength, and elastic properties.

Keywords: asteroids; impact phenomena; near-earth objects
System-level Fractionation of Carbon from Disk and Planetesimal Processing

Finding and characterizing extrasolar Earth analogs will rely on interpretation of the planetary system's environmental context. The total budget and fractionation between C-H-O species sensitively affect the climatic and geodynamic state of terrestrial worlds, but their main delivery channels are poorly constrained. We connect numerical models of volatile chemistry and pebble coagulation in the circumstellar disk with the internal compositional evolution of planetesimals during the primary accretion phase. Our simulations demonstrate that disk chemistry and degassing from planetesimals operate on comparable timescales and can fractionate the relative abundances of major water and carbon carriers by orders of magnitude. As a result, individual planetary systems with significant planetesimal processing display increased correlation in the volatile budget of planetary building blocks relative to no internal heating. Planetesimal processing in a subset of systems increases the variance of volatile contents across planetary systems. Our simulations thus suggest that exoplanetary atmospheric compositions may provide constraints on when a specific planet formed.

Keywords: astrobiology; exoplanet atmospheres; extrasolar rocky planets; planet formation; planetesimals; pre-biotic astrochemistry
Expected Brightness of Ejecta Caused by the DART Impact

We estimate the volume of material that could be excavated from asteroid Dimorphos and expelled into the surrounding space by the DART impact on 2022 September 26. What emerges from our computations is that the total volume of ejected material could be as high as 5710 m3. Assuming that the fraction of fine-dust particles constitutes 5% of this volume, we estimate the apparent brightness of the ejecta to be (6.5 ± 1.5) mag in the V filter. This makes ground-based astronomical observations of the DART impact on asteroid Dimorphos with small telescopes feasible.

Keywords: impact phenomena; near-earth objects; asteroids; ejecta; broad band photometry; astronomical simulations
Identifying Acoustic Wave Sources on the Sun. II. Improved Filter Techniques for Source Wavefield Seismology

In this paper, we refine a previously developed acoustic source filter, improving its reliability and extending its capabilities. We demonstrate how to fine-tune the filter to meet observational constraints and focus on specific wave-front speeds. This refinement enables discrimination of acoustic source depths and tracking of local source wave fronts, thereby facilitating ultralocal helioseismology. By utilizing the photospheric Doppler signal from a subsurface source in a MURaM simulation, we demonstrate that robust ultralocal three-dimensional helioseismic inversions for the granular flows and the local sound speed to depths of at least 80 km below the photosphere are possible. The capabilities of the National Science Foundation's new Daniel K. Inouye Solar Telescope will enable such measurements of the real Sun.

Keywords: the sun; solar physics; solar photosphere; helioseismology; solar granulation; solar oscillations
A SPectroscopic Survey of Biased Halos in the Reionization Era (ASPIRE): A First Look at the Rest-frame Optical Spectra of z > 6.5 Quasars Using JWST

Studies of rest-frame optical emission in quasars at z > 6 have historically been limited by the wavelengths accessible by ground-based telescopes. The James Webb Space Telescope (JWST) now offers the opportunity to probe this emission deep into the reionization epoch. We report the observations of eight quasars at z > 6.5 using the JWST/NIRCam Wide Field Slitless Spectroscopy as a part of the "A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE)" program. Our JWST spectra cover the quasars' emission between rest frame ~4100 and 5100 Å. The profiles of these quasars' broad Hβ emission lines span a full width at half maximum from 3000 to 6000 km s-1. The Hβ-based virial black hole (BH) masses, ranging from 0.6 to 2.1 billion solar masses, are generally consistent with their Mg II-based BH masses. The new measurements based on the more reliable Hβ tracer thus confirm the existence of a billion solar-mass BHs in the reionization epoch. In the observed [O III] λ λ 4960,5008 doublets of these luminous quasars, broad components are more common than narrow core components (≤ 1200 km s-1), and only one quasar shows stronger narrow components than broad. Two quasars exhibit significantly broad and blueshifted [O III] emission, thought to trace galactic-scale outflows, with median velocities of -610 and -1430 km s-1 relative to the [C II] 158 μm line. All eight quasars show strong optical Fe II emission and follow the eigenvector 1 relations defined by low-redshift quasars. The entire ASPIRE program will eventually cover 25 quasars and provide a statistical sample for the studies of the BHs and quasar spectral properties.

Keywords: quasars; supermassive black holes; reionization
Automated Scheduling of Doppler Exoplanet Observations at Keck Observatory

Precise Doppler studies of extrasolar planets require fine-grained control of observational cadence, i.e., the timing of and spacing between observations. We present a novel framework for scheduling a set of Doppler campaigns with different cadence requirements at the W. M. Keck Observatory. For a set of observing programs and allocated nights on an instrument, our software optimizes the timing and ordering of ∼1000 observations within a given observing semester. We achieve a near-optimal solution in real-time using a hierarchical Integer Linear Programming framework. Our scheduling formulation optimizes over the roughly 103000 possible orderings. A top level optimization finds the most regular sequence of allocated nights by which to observe each host star in the request catalog based on a frequency specified in the request. A second optimization scheme minimizes the slews and downtime of the instrument. We have assessed our algorithms performance with simulated data and with the real suite of Doppler observations of the California Planet Search in 2023.

Keywords: astronomical methods; observational astronomy
GLEAM: Galaxy Line Emission & Absorption Modeling

We present Galaxy Line Emission & Absorption Modeling (GLEAM), a Python tool for fitting Gaussian models to emission and absorption lines in large samples of 1D extragalactic spectra. GLEAM is tailored to work well in batch mode without much human interaction. With GLEAM, users can uniformly process a variety of spectra, including galaxies and active galactic nuclei, in a wide range of instrument setups and signal-to-noise regimes. GLEAM also takes advantage of multiprocessing capabilities to process spectra in parallel. With the goal of enabling reproducible workflows for its users, GLEAM employs a small number of input files, including a central, user-friendly configuration in which fitting constraints can be defined for groups of spectra and overrides can be specified for edge cases. For each spectrum, GLEAM produces a table containing measurements and error bars for the detected spectral lines and continuum and upper limits for nondetections. For visual inspection and publishing, GLEAM can also produce plots of the data with fitted lines overlaid. In the present paper, we describe GLEAM's main features, the necessary inputs, expected outputs, and some example applications, including thorough tests on a large sample of optical/infrared multi-object spectroscopic observations and integral field spectroscopic data. GLEAM is developed as an open-source project hosted at https://github.com/multiwavelength/gleam and welcomes community contributions.

Keywords: astronomy software; astronomical techniques; astronomy data analysis; open source software; spectroscopy; galaxies; active galactic nuclei
How Nonlinearity Changes Different Parameters in the Solar Corona

We consider different velocity amplitudes of incident waves to study nonlinearity effects on the plasma parameters around a magnetic null point in the solar corona. This could query the seismological methods used to observe and interpret damping profiles of oscillations of magnetic structures, based on linear theory. To this end, initially symmetric fast magnetoacoustic waves with three different amplitudes are applied to the system to pursue the effect of nonlinearity on the resulting plasma heating and flows. The dynamic evolution is investigated by solving the resistive MHD equations in a Cartesian domain by the PLUTO code. The considered magnetic null point is surrounded by an initially constant density and temperature plasma. Pursuing the partition of different energy components can shed light on our understanding of the energy release mechanisms. It is found that nonlinear behavior could be the reason for the occurring magnetic reconnection and the related excitation of coronal jets. Furthermore, the fully nonlinear simulation run results in a high temperature and a high current density accumulation and less twisting along the wave accumulation direction, which is even higher than the heating at the magnetic null point itself. Moreover, it is found that there is no significant amplification in the velocity profile. This could be related to the fact that there are not any clear correlations between jets and flares. Furthermore, it is illustrated that the period of the oscillations depends on the amplitude of the initial perturbation, obtaining a shorter period for the fully nonlinear case.

Keywords: magnetohydrodynamics; the sun; solar coronal waves
The Outburst of the Young Star Gaia19bey

We report photometry and spectroscopy of the outburst of the young stellar object Gaia19bey. We have established the outburst light curve with archival Gaia "G," ATLAS "Orange," Zwicky Transient Facility r-band, and Pan-STARRS "rizy"-filter photometry, showing an outburst of ~4 yr duration, longer than typical EX Lupi objects but shorter than FU Orionis objects. Its pre-outburst spectral energy distribution shows a flat far-infrared spectrum, confirming the early evolutionary state of Gaia19bey and its similarity to other deeply embedded young stars experiencing outbursts. A lower limit to the peak outburst luminosity is ~182 ${L}_{\odot }$ at an assumed distance of 1.4 kpc, the minimum plausible distance. Infrared and optical spectroscopy near maximum light show an emission line spectrum, including H I lines, strong red Ca II emission, other metal emission lines, infrared CO bandhead emission, and a strong infrared continuum. Toward the end of the outburst, the emission lines have all but disappeared and the spectrum has changed into an almost pure continuum spectrum. This indicates a cessation of magnetospheric accretion activity. The near-infrared colors have become redder as Gaia19bey has faded, indicating a cooling of the continuum component. Near the end of the outburst, the only remaining strong emission lines are forbidden shock-excited emission lines. Adaptive optics integral-field spectroscopy shows the H2 1-0 S(1) emission with the morphology of an outflow cavity and the extended emission in the [Fe II] line at 1644 nm with the morphology of an edge-on disk. However, we do not detect any large-scale jet from Gaia19bey.

Keywords: eruptive variable stars; young stellar objects; fu orionis stars
Structure and Internal Kinematics of Nine Inner Milky Way Globular Clusters

This study constitutes part of a larger effort aimed at better characterizing the Galactic globular clusters (GGCs) located toward the inner Milky Way bulge and disk. Here, we focus on internal kinematics of nine GGCs, obtained from space-based imaging over time baselines of >9 yr. We exploit multiple avenues to assess the dynamical state of the target GGCs, constructing radial profiles of projected stellar density, proper motion dispersion, and anisotropy. We posit that two-thirds (6/9) of our target GGCs are in an advanced dynamical state, and are close to (or have recently undergone) core-collapse, supported by at least two lines of evidence. First, we find relatively steep proper motion dispersion profiles, in accord with literature values for core-collapsed GGCs. Second, we find that our sample is, in the mean, isotropic even out to their half-light radii, although one of our target clusters (NGC 6380) is tangentially anisotropic at >1σ beyond its half-light radius, in accord with theoretical predictions for clusters evolving in strong tidal fields. Our proper motion dispersion and anisotropy profiles are made publicly available. * Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-15065.

Keywords: globular star clusters; star clusters; stellar dynamics
MCR-TRGB: A Multiwavelength-covariant, Robust Tip of the Red Giant Branch Measurement Method

We present a new method to measure colors and magnitudes of the tip of the red giant branch (TGRB) in multiple bandpasses simultaneously by fitting an n-dimensional Gaussian to photometry of candidate tip stars. We demonstrate that this method has several advantages over traditional edge detection, particularly in regimes where the TRGB magnitude is strongly color dependent, as is the case in the near-infrared (NIR). We apply this method to a re-reduction of a set of optical and NIR Hubble Space Telescope data originally presented in Dalcanton et al. (D12). The re-reduction takes advantage of the increased depth and accuracy in the NIR photometry enabled by simultaneous reduction with higher-resolution optical data in crowded fields. We compare three possible absolute calibrations of the resulting apparent TRGB measurements, one adopting the same distance moduli as in D12 and two based on predicted TRGB absolute magnitudes from two widely used, modern sets of model isochrones. We find systematic offsets among the model absolute calibrations at the ∼0.15 mag level, in line with previous investigations. The models also have difficulty reproducing the optical-NIR color-magnitude behavior of our measurements, making these observations a useful benchmark for future improvements. * Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Keywords: distance indicators; red giant tip; near infrared astronomy
High Heat Flux near Miranda's Inverness Corona Consistent with a Geologically Recent Heating Event

Uranus's moon Miranda has a complex surface reflecting multiple episodes of activity. We estimated the heat flux near Inverness Corona, the youngest terrain on Miranda ( ${100}_{-100}^{+400}$ Ma), to gain insight into recent endogenic resurfacing. We modeled flexure associated with Argier Rupes, which separates Inverness from the Cratered Terrain. Our results indicate an elastic thickness of 2.2-3.1 km and a heat flux of 35-140 mW m-2 in this region, assuming Miranda's lithosphere is composed of pure H2O ice without porosity. Because the formation of the bounding flexure that we analyzed followed the formation of Argier Rupes, our results indicate that Miranda experienced high heat flux in the past ${100}_{-100}^{+400}$ Ma. These results are also consistent with heating from a past resonance, possibly an Ariel-Umbriel 5:3 mean motion resonance, estimated to have generated heat fluxes >100 mW m-2 on Miranda. However, if Miranda instead has a porous lithosphere, our heat flux estimates are lower: 34-135 mW m-2 for 5% porosity, 29-114 mW m-2 for 15% porosity, and 20-81 mW m-2 for 25% porosity. Alternatively, if Miranda's lithosphere includes NH3-hydrates, then our are estimates are even lower, 7-56 mW m-2 without porosity. These estimates decrease further when assuming NH3-hydrates and porosity: 7-54 mW m-2 for 5% porosity, 6-46 mW m-2 for 15% porosity, and 4-32 mW m-2 for 25% porosity. Better constraints on Miranda's heat fluxes require more information on its ice shell properties.

Keywords: uranian satellites; natural satellites (solar system); tectonics; planetary science; natural satellite surfaces
TESS Data for Asteroseismology: Photometry

Over the last two decades, asteroseismology has increasingly proven to be the observational tool of choice for the study of stellar physics, aided by the high quality of data available from space-based missions such as CoRoT, Kepler, K2, and the Transiting Exoplanet Survey Satellite (TESS). TESS in particular will produce more than an order of magnitude more such data than has ever been available before. While the standard TESS mission products include light curves from 120 s observations suitable for both exoplanet and asteroseismic studies, they do not include light curves for the vastly larger number of targets observed by the mission at a longer 1800 s cadence in Full Frame Images (FFIs). To address this lack, the TESS Data for Asteroseismology (T'DA) group under the TESS Asteroseismic Science Consortium (TASC) has constructed an open-source pipeline focused on producing light curves for all stars observed by TESS at all cadences, currently including stars down to a TESS magnitude of 15. The pipeline includes target identification, background estimation and removal, correction of FFI time stamps, and a range of potential photometric extraction methodologies, though aperture photometry is currently the default approach. For the brightest targets, we transparently apply a halo photometry algorithm to construct a calibrated light curve from unsaturated pixels in the image. In this paper, we describe in detail the algorithms, functionality, and products of this pipeline and summarize the noise metrics for the light curves. Companion papers will address the removal of systematic noise sources from our light curves, and a stellar variability classification from these.

Keywords: asteroseismology; astronomy data analysis; ccd photometry; variable stars
The Energetics of the Central Engine in the Powerful Quasar 3C 298

The compact steep-spectrum radio source 3C 298 (redshift of 1.44) has the largest 178 MHz luminosity in the Third Cambridge Revised Catalogue (3CR); its radio lobes are among the most luminous in the universe. The plasma state of the radio lobes is modeled with the aid of interferometric radio observations (in particular, the new Low Frequency Array observation and archival MERLIN data) and archival single-station data. It is estimated that the long-term time-averaged jet power required to fill these lobes with leptonic plasma is $\overline{Q}\,\approx 1.28\pm 0.51\times {10}^{47}\,\mathrm{erg}\,{{\rm{s}}}^{-1}$ , rivaling the largest time-averaged jet powers from any quasar. Supporting this notion of extraordinary jet power is a 0.5-10 keV luminosity of ≈ 5.2 × 1046 erg s-1, comparable to luminous blazars, yet there is no other indication of strong relativistic beaming. We combine two new high signal-to-noise ratio optical spectroscopic observations from the Hobby-Eberly Telescope with archival Hubble Space Telescope, Two Micron All Sky Survey, and Galaxy Evolutionary Explorer data to compute a bolometric luminosity from the accretion flow of L bol ≈ 1.55 ± 0.15 × 1047 erg s-1. The ratio, $\overline{Q}/{L}_{\mathrm{bol}}\approx 1$ , is the approximate upper limit for quasars. Characteristic of a large $\overline{Q}/{L}_{\mathrm{bol}}$ , we find an extreme-ultraviolet (EUV) spectrum that is very steep (the "EUV deficit" of powerful radio quasars relative to radio-quiet quasars), and this weak ionizing continuum is likely a contributing factor to the relatively small equivalent widths of the broad emission lines in this quasar.

Keywords: quasars