adsabs/SciX_UAT_keywords huggingface dataset:
The Early Light Curve of the Type Ia Supernova 2021hpr in NGC 3147: Progenitor Constraints with the Companion Interaction Model

The progenitor system of Type Ia supernovae (SNe Ia) is expected to be a close binary system consisting of a carbon/oxygen white dwarf (WD) and a nondegenerate star or another WD. Here, we present results from high-cadence monitoring observations of SN 2021hpr in a spiral galaxy, NGC 3147, and constraints on the progenitor system based on its early multicolor light-curve data. First, we classify SN 2021hpr as a normal SN Ia from its long-term photometric and spectroscopic data. More interestingly, we found a significant "early excess" in the light curve over a simple power-law ~t 2 evolution. The early light curve evolves from blue to red to blue during the first week. To explain this, we fitted the early part of the BVRI-band light curves with a two-component model consisting of ejecta-companion interaction and a simple power-law model. The early excess and its color can be explained by shock-cooling emission due to a companion star having a radius of 8.84 ± 0.58 R ⊙. We also examined Hubble Space Telescope preexplosion images, finding no detection of a progenitor candidate, consistent with the above result. However, we could not detect signs of a significant amount of stripped mass from a nondegenerate companion star (≲0.003 M ⊙ for Hα emission). The early excess light in the multiband light curve supports a nondegenerate companion in the progenitor system of SN 2021hpr. At the same time, the nondetection of emission lines opens the door for other methods to explain this event.

Keywords: type ia supernovae; white dwarf stars; supernovae; astrophysical explosive burning; transient sources; time domain astronomy
The Galactic Center Black Hole, Sgr A*, as a Probe of New Gravitational Physics with the Scalaron Fifth Force

The Galactic Center black hole (Sgr A*) provides an ideal laboratory for astronomical tests of new gravitational physics. This work reports that curvature correction (f(R)) to quantum vacuum fluctuations naturally yields a Yukawa-type scalar fifth force with potential $\exp \left(-{M}_{\psi }r\right)/r$ , where Mψ is the mass of the f(R) scalarons. Estimating the UV and IR cutoff scales of vacuum fluctuations, the Yukawa coupling strength is connected to the scalaron field amplitude. Whereas recently constrained Yukawa coupling and range correspond to light scalarons with Mψ = (1.37 × 10-21-5.49 × 10-20) eV, vacuum fluctuations yield a massive scalaron with Mψ = 10-16 eV. Scalaron-induced periastron shift of stellar orbits near Sgr A* has been studied with respect to the semimajor axis in the range a = 10-1000 au. It is found that the scalarons resulting from quantum fluctuations affect the precession of orbits with a = 128-256 Rs. The possibility of future constraints on massive scalarons in observations near Sgr A* is discussed. This is a new and independent effort to express a prototype quantum gravity effect in terms of astronomically accessible quantities.

Keywords: galactic center; gravitation
Impact Crater Morphometry on Pluto: Implications for Surface Composition and Evolution

New Horizons showed that Pluto exhibits a wide range of geologic groups, with much of the surface modified by volatile ice processes. Impact craters are a valuable tool to investigate how these regions have evolved, as they record the effects of various modification mechanisms and retain information on the properties of the bedrock ice(s). In this work, we use Pluto's crater population to quantify the extent of surface modification and identify variations in surface properties on Pluto. In this study, we have measured the relative depth of Pluto's craters compared to minimally modified water-ice craters to interpret how the craters may have evolved and/or what the information tells us about the surface properties of the bedrock. We found a trend of increasing crater relative depth from southeast to northwest that may reflect the conditions of an ancient surface when a thicker layer of volatile ice may have existed, possibly changed by polar wander after the Sputnik impact. We have identified anomalously deep craters across Pluto's surface, with a concentration in Cthulhu Macula, suggesting different bedrock-ice properties in this region. Other deep craters may be influenced by extraneous factors, such as impactor speed. Overall, this study expands on our understanding of the evolution and composition of Pluto's surface and sets a road map for further investigations into Pluto's surface evolution.

Keywords: pluto; planetary surfaces; craters; ice physics
Simulation of Stark-broadened Hydrogen Balmer-line Shapes for DA White Dwarf Synthetic Spectra

White dwarfs (WDs) are useful across a wide range of astrophysical contexts. The appropriate interpretation of their spectra relies on the accuracy of WD atmosphere models. One essential ingredient of atmosphere models is the theory used for the broadening of spectral lines. To date, the models have relied on Vidal et al., known as the unified theory of line broadening (VCS). There have since been advancements in the theory; however, the calculations used in model atmosphere codes have only received minor updates. Meanwhile, advances in instrumentation and data have uncovered indications of inaccuracies: spectroscopic temperatures are roughly 10% higher and spectroscopic masses are roughly 0.1 M ⊙ higher than their photometric counterparts. The evidence suggests that VCS-based treatments of line profiles may be at least partly responsible. Gomez et al. developed a simulation-based line-profile code Xenomorph using an improved theoretical treatment that can be used to inform questions around the discrepancy. However, the code required revisions to sufficiently decrease noise for use in model spectra and to make it computationally tractable and physically realistic. In particular, we investigate three additional physical effects that are not captured in the VCS calculations: ion dynamics, higher-order multipole expansion, and an expanded basis set. We also implement a simulation-based approach to occupation probability. The present study limits the scope to the first three hydrogen Balmer transitions (Hα, Hβ, and Hγ). We find that screening effects and occupation probability have the largest effects on the line shapes and will likely have important consequences in stellar synthetic spectra.

Keywords: white dwarf stars; plasma physics; da stars; stellar atmospheres; fundamental parameters of stars
The Evolutionary Track of H/He Envelopes of the Observed Population of Sub-Neptunes and Super-Earths

The observational detection of a localized reduction in the small planet occurrence rate, sometimes termed a "gap," is an exciting discovery because of the implications for planet evolutionary history. This gap appears to define a transition region in which sub-Neptune planets are believed to have lost their H/He envelopes, potentially by photoevaporation or core powered mass loss, and have thus been transformed into bare core terrestrial planets. Here we investigate the transition between sub-Neptunes and super-Earths using a real sample of observed small close-in planets and applying envelope evolution models of the H/He envelope together with the mass-radius diagram and a photoevaporation model. We find that photoevaporation can explain the H/He envelope loss of most super-Earths in 100 Myr, although an additional loss mechanism appears necessary in some planets. We explore the possibility that these planets' families have different core masses and find a continuum in the primordial population of the strongly irradiated super-Earths and the sub-Neptunes. Our analysis also shows that close-orbiting sub-Neptunes with R < 3.5 R⊕ typically lose ∼30% of their primordial envelope.

Keywords: exoplanets; extrasolar rocky planets; mini neptunes; exoplanet atmospheres; exoplanet structure
The Sun's Mean Line-of-sight Field

In this paper, I regard the Sun-as-a-star magnetic field (i.e., the mean field) as a filter for the spherical harmonic components of the photospheric field, and then calculate the transmission coefficients of this filter. The coefficients for each harmonic, Y l m , are listed in three tables according to their dependence on B 0, the observer's latitude in the star's polar coordinate system. These coefficients are used to interpret the 46 yr sequence of daily mean-field measurements at the Wilcox Solar Observatory. I find that the nonaxisymmetric part of the field originates in the ${Y}_{1}^{1}$ , ${Y}_{2}^{2}$ , and a combination of the ${Y}_{3}^{3}$ and ${Y}_{3}^{1}$ harmonic components. The axisymmetric part of the field originates in ${Y}_{2}^{0}$ plus a B 0-dependent combination of the ${Y}_{1}^{0}$ and ${Y}_{3}^{0}$ components. The power spectrum of the field has peaks at frequencies corresponding to the ~27 day synodic equatorial rotation period and its second and third harmonics. Each of these peaks has fine structure on its low-frequency side, indicating magnetic patterns that rotate slowly under the influence of differential rotation and meridional flow. The sidebands of the fundamental mode resolve into peaks corresponding to periods of ~28.5 and ~30 days, which tend to occur at the start of sunspot maximum, whereas the ~27 day period tends to occur toward the end of sunspot maximum. We might expect similar rotational sidebands to occur in magnetic observations of other Sun-like stars and to be a useful complement to asteroseismology studies of convection and magnetic fields in those stars.

Keywords: solar magnetic fields; solar rotation; solar cycle; stellar magnetic fields
Heavy Elements Unveil the Non-primordial Origin of the Giant H I Ring in Leo

The origin and fate of the most extended extragalactic neutral cloud known in the local universe, the Leo ring, is still debated 38 yr after its discovery. Its existence is alternatively attributed to leftover primordial gas with some low level of metal pollution versus enriched gas stripped during a galaxy-galaxy encounter. Taking advantage of Multi Unit Spectroscopic Explorer operating at the Very Large Telescope, we performed optical integral field spectroscopy of three H I clumps in the Leo ring where ultraviolet continuum emission has been found. We detected, for the first time, ionized hydrogen in the ring and identify four nebular regions powered by massive stars. These nebulae show several metal lines ([O III], [N II], [S II]) that allowed reliable measures of metallicities, found to be close to or above the solar value (0.8 ≤ Z/Z⊙ ≤ 1.4). Given the faintness of the diffuse stellar counterparts, less than 3% of the observed heavy elements could have been produced locally in the main body of the ring and not much more than 15% in the H I clump toward M96. This inference, and the chemical homogeneity among the regions, convincingly demonstrates that the gas in the ring is not primordial, but has been pre-enriched in a galaxy disk, then later removed and shaped by tidal forces and it is forming a sparse population of stars.

Keywords: chemical abundances; intergalactic clouds; interacting galaxies; h ii regions
The Sloan Digital Sky Survey Reverberation Mapping Project: Photometric g and i Light Curves

The Sloan Digital Sky Survey (SDSS) Reverberation Mapping program monitors 849 active galactic nuclei (AGNs) both spectroscopically and photometrically. The photometric observations used in this work span over 4 yr and provide an excellent baseline for variability studies of these objects. We present the photometric light curves from 2014 to 2017 obtained by the Steward Observatory's Bok telescope and the Canada-France-Hawaii telescope with MegaCam. We provide details on the data acquisition and processing of the data from each telescope, the difference imaging photometry used to produce the light curves, and the calculation of a variability index to quantify each AGN's variability. We find that the Welch-Stetson J index provides a useful characterization of AGN variability and can be used to select AGNs for further study.

Keywords: active galactic nuclei
Revisiting Kepler Transiting Systems: Unvetting Planets and Constraining Relationships among Harmonics in Phase Curves

Space-based photometric missions widely use statistical validation tools for vetting transiting planetary candidates, particularly when other traditional methods of planet confirmation are unviable. In this paper, we refute the planetary nature of three previously validated planets-Kepler-854 b, Kepler-840 b, and Kepler-699 b-and possibly a fourth, Kepler-747 b, using updated stellar parameters from Gaia and phase-curve analysis. In all four cases, the inferred physical radii rule out their planetary nature given the stellar radiation the companions receive. For Kepler-854 b, the mass derived from the host star's ellipsoidal variation, which had not been part of the original vetting procedure, similarly points to a nonplanetary value. To contextualize our understanding of the phase curve for stellar-mass companions in particular and extend our understanding of high-order harmonics, we examine Kepler eclipsing binaries with periods between 1.5 and 10 days. Using a sample of 20 systems, we report a strong power-law relation between the second cosine harmonic of the phase-curve signal and the higher cosine harmonics, which supports the hypothesis that those signals arise from the tidal interaction between the binary components. We find that the ratio between the second- and third-harmonic amplitudes is 2.24 ± 0.48, in good agreement with the expected value of 2.4 from the classical formalism for the ellipsoidal distortion.

Keywords: transit photometry; exoplanet detection methods; photometry
Dual-band Fourier-transform Millimeter-wave Spectrometry for In Situ Gas Sensing

The exploration of icy body composition in the solar system has often involved spectroscopic measurements of volatiles detected with remote sensing, such measurements portray materials naturally expelled from the surface that enter the exosphere and potentially escape into space. Variations in the ratio of deuterium and hydrogen in these measurements have led to inconclusive hypotheses regarding potential cometary origins of Earth's ocean water and/or organics. Observational biases regarding unknown previous processing of the observable ejected materials necessitates studies of more dormant, less-processed bodies. Landed missions on comets have brought focus onto the development of small, sensitive instrumentation capable of similar composition measurements of the nascent surface and near-surface materials. We present an evolution of our compact Fourier-transform millimeter-wave cavity spectrometer that is tuned for sensitivity at 80.6 and 183 GHz where HDO and H2O exhibit resonance features. We discuss both a low-SWaP (size-weight and power) architecture that uses custom microchip transceiver elements as well as a modular configuration using traditional GaAs-based millimeter-wave hardware. New design features for these systems including quartz-based coupling elements, system thermal management, and a separable clocking board are discussed in addition to sensitivity studies and applications in potential mission scenarios.

Keywords: millimeter-wave spectroscopy; molecular spectroscopy; high resolution spectroscopy; comet surfaces; space vehicle instruments
Medium-term Predictions of F10.7 and F30 cm Solar Radio Flux with the Adaptive Kalman Filter

The solar radio flux at F10.7 and F30 cm is required by most models characterizing the state of the Earth's upper atmosphere, such as the thermosphere and ionosphere, to specify satellite orbits, re-entry services, collision avoidance maneuvers, and modeling of the evolution of space debris. We develop a method called RESONANCE (Radio Emissions from the Sun: ONline ANalytical Computer-aided Estimator) for the prediction of the 13-month smoothed monthly mean F10.7 and F30 indices 1-24 months ahead. The prediction algorithm has three steps. First, we apply a 13-month optimized running mean technique to effectively reduce the noise in the radio flux data. Second, we provide initial predictions of the F10.7 and F30 indices using the McNish-Lincoln method. Finally, we improve these initial predictions by developing an adaptive Kalman filter with identification of the error statistics. The rms error of predictions with lead times from 1 to 24 months is 5-27 solar flux units (sfu) for the F10.7 index and 3-16 sfu for F30, which statistically outperforms current algorithms in use. The proposed approach based on the Kalman filter is universal and can be applied to improve the initial predictions of a process under study provided by any other forecasting method. Furthermore, we present a systematic evaluation of re-entry forecast as an application to test the performance of F10.7 predictions on past ESA re-entry campaigns for payloads, rocket bodies, and space debris that re-entered from 2006 to 2019 June. The test results demonstrate that the predictions obtained by RESONANCE in general also lead to improvements in the forecasts of re-entry epochs.

Keywords: the sun; astronomy data analysis; thermosphere; solar radio emission; earth atmosphere; solar cycle
Evolution of Solar Wind Turbulence from 0.1 to 1 au during the First Parker Solar Probe-Solar Orbiter Radial Alignment

The first radial alignment between Parker Solar Probe and Solar Orbiter spacecraft is used to investigate the evolution of solar wind turbulence in the inner heliosphere. Assuming ballistic propagation, two 1.5 hr intervals are tentatively identified as providing measurements of the same plasma parcels traveling from 0.1 to 1 au. Using magnetic field measurements from both spacecraft, the properties of turbulence in the two intervals are assessed. Magnetic spectral density, flatness, and high-order moment scaling laws are calculated. The Hilbert-Huang transform is additionally used to mitigate short sample and poor stationarity effects. Results show that the plasma evolves from a highly Alfvénic, less-developed turbulence state near the Sun, to fully developed and intermittent turbulence at 1 au. These observations provide strong evidence for the radial evolution of solar wind turbulence.

Keywords: magnetohydrodynamics; alfven waves; space plasmas; interplanetary turbulence; solar wind
New Observational H(z) Data from Full-spectrum Fitting of Cosmic Chronometers in the LEGA-C Survey

In this work, we perform a full-spectrum fitting of 350 massive and passive galaxies selected as cosmic chronometers from the LEGA-C ESO public survey to derive their stellar ages, metallicities, and star formation histories. We extensively test our results by assessing their dependence on the possible contribution of dust, calibration of noise and signal, and use of photometric data in addition to spectral information; we also identify indicators of the correct convergence of the results, including the shape of the posterior distributions, the analysis of specific spectral features, and the correct reproduction of the observed spectrum. We derive a clear age-redshift trend compatible with the aging in a standard cosmological model showing a clear downsizing pattern, with more massive galaxies being formed at higher redshift (z f ~ 2.5) with respect to less massive ones (z f ~ 2). From these data, we measure the differential aging of this population of cosmic chronometers to derive a new measurement of the Hubble parameter, obtaining $H(z=0.8)=113.1\pm 15.1(\mathrm{stat}.{)}_{-11.3}^{+29.1}(\mathrm{syst}.)$ . This analysis allows us to compare for the first time the differential ages of cosmic chronometers measured on the same sample with two completely different methods, the full-spectrum fit (this work) and the analysis of Lick indices, known to correlate with the age and metallicity of the stellar populations. Albeit an understood offset in the absolute ages, the differential ages have proven to be extremely compatible between the two methods, despite the very different data, assumptions, and models considered, demonstrating the robustness of the method.

Keywords: cosmological evolution; observational cosmology; galaxy ages
Multiscale Stamps for Real-time Classification of Alert Streams

In recent years, automatic classifiers of image cutouts (also called "stamps") have been shown to be key for fast supernova discovery. The Vera C. Rubin Observatory will distribute about ten million alerts with their respective stamps each night, enabling the discovery of approximately one million supernovae each year. A growing source of confusion for these classifiers is the presence of satellite glints, sequences of point-like sources produced by rotating satellites or debris. The currently planned Rubin stamps will have a size smaller than the typical separation between these point sources. Thus, a larger field-of-view stamp could enable the automatic identification of these sources. However, the distribution of larger stamps would be limited by network bandwidth restrictions. We evaluate the impact of using image stamps of different angular sizes and resolutions for the fast classification of events (active galactic nuclei, asteroids, bogus, satellites, supernovae, and variable stars), using data from the Zwicky Transient Facility. We compare four scenarios: three with the same number of pixels (small field of view with high resolution, large field of view with low resolution, and a multiscale proposal) and a scenario with the full stamp that has a larger field of view and higher resolution. Compared to small field-of-view stamps, our multiscale strategy reduces misclassifications of satellites as asteroids or supernovae, performing on par with high-resolution stamps that are 15 times heavier. We encourage Rubin and its Science Collaborations to consider the benefits of implementing multiscale stamps as a possible update to the alert specification.

Keywords: astroinformatics; transient detection; sky surveys
Evidence of Core Growth in the Dragon Infrared Dark Cloud: A Path for Massive Star Formation

A sample of 1.3 mm continuum cores in the Dragon infrared dark cloud (also known as G28.37+0.07 or G28.34+0.06) is analyzed statistically. Based on their association with molecular outflows, the sample is divided into protostellar and starless cores. Statistical tests suggest that the protostellar cores are more massive than the starless cores, even after temperature and opacity biases are accounted for. We suggest that the mass difference indicates core mass growth since their formation. The mass growth implies that massive star formation may not have to start with massive prestellar cores, depending on the core mass growth rate. Its impact on the relation between core mass function and stellar initial mass function is to be further explored.

Keywords: star formation; infrared dark clouds; stellar jets; young stellar objects; protostars; observational astronomy; millimeter astronomy; nonparametric hypothesis tests; astrostatistics strategies; young massive clusters; massive stars; interstellar filaments