adsabs/SciX_UAT_keywords huggingface dataset:
Influence of Large-scale Interplanetary Structures on the Propagation of Solar Energetic Particles: The Multispacecraft Event on 2021 October 9

An intense solar energetic particle (SEP) event was observed on 2021 October 9 by multiple spacecraft distributed near the ecliptic plane at heliocentric radial distances R ≲ 1 au and within a narrow range of heliolongitudes. A stream interaction region (SIR), sequentially observed by Parker Solar Probe (PSP) at R = 0.76 au and 48° east from Earth (ϕ = E48°), STEREO-A (at R = 0.96 au, ϕ = E39°), Solar Orbiter (SolO; at R = 0.68 au, ϕ = E15°), BepiColombo (at R = 0.33 au, ϕ = W02°), and near-Earth spacecraft, regulated the observed intensity-time profiles and the anisotropic character of the SEP event. PSP, STEREO-A, and SolO detected strong anisotropies at the onset of the SEP event, which resulted from the fact that PSP and STEREO-A were in the declining-speed region of the solar wind stream responsible for the SIR and from the passage of a steady magnetic field structure by SolO during the onset of the event. By contrast, the intensity-time profiles observed near Earth displayed a delayed onset at proton energies ≳13 MeV and an accumulation of ≲5 MeV protons between the SIR and the shock driven by the parent coronal mass ejection (CME). Even though BepiColombo, STEREO-A, and SolO were nominally connected to the same region of the Sun, the intensity-time profiles at BepiColombo resemble those observed near Earth, with the bulk of low-energy ions also confined between the SIR and the CME-driven shock. This event exemplifies the impact that intervening large-scale interplanetary structures, such as corotating SIRs, have in shaping the properties of SEP events.

Keywords: corotating streams; solar energetic particles; solar coronal mass ejection shocks
Suppressed or Enhanced Central Star Formation Rates in Late-type Barred Galaxies

Bars in disk-dominated galaxies are able to drive gas inflow inside the corotation radius, thus enhancing the central star formation rate (SFR). Previous work, however, has found that disk-dominated galaxies with centrally suppressed SFRs frequently host a bar. Here we investigate possible causes for the suppression of central SFRs in such cases. We compare the physical properties of a sample of disk-dominated barred galaxies with high central SFRs (HC galaxies) with those of a sample of disk-dominated barred galaxies with low central SFRs (LC galaxies). We find that the two samples have, on average, similar H I content and bars of similar strength. But we also find that the HCs have bluer colors than the LCs, and that outside the bar region, they host stronger spiral arms than the LCs, where closed rings are more often seen. We discuss and evaluate the possible causes for the suppression of the central SFR in the LC galaxies as opposed to its enhancement in the HC galaxies.

Keywords: disk galaxies; galaxy structure; spiral arms; star formation; barred spiral galaxies; interstellar atomic gas
X-Ray Spectroscopic Evidence of Charge Exchange Emission in the Disk of M51

In the disks of spiral galaxies, diffuse soft X-ray emission is known to be strongly correlated with star-forming regions. However, this emission is not simply from a thermal-equilibrium plasma and its origin remains greatly unclear. In this work, we present an X-ray spectroscopic analysis of the emission from the northern hot spot; a region with enhanced star formation off the nucleus of M51. Based on the high spectral resolution data from XMM-Newton/Reflection Grating Spectrometer (RGS) observations, we unambiguously detect a high G ratio ( ${3.2}_{-1.5}^{+6.9}$ ) of the O VII Heα triplet. This high G ratio is also spatially confirmed by oxygen emission-line maps from the same data. A physical model consisting of a thermal plasma and its charge exchange (CX) with neutral cool gas gives a good explanation for the G ratio and the entire RGS spectra. This model also gives a satisfactory characterization of the complementary Chandra ACIS-S data, which enables a direct imaging of the diffuse emission, tracing the hot plasma across the galaxy. The hot plasma has a similar characteristic temperature of ~0.34 keV and an approximately solar metallicity. The CX contributes ~50% to the diffuse emission in the 0.4-1.8 keV band, suggesting an effective hot/cool gas interface area about five times the geometric area of the M51 disk. Therefore, the CX appears to play a major role in the soft X-ray production and may be used as a powerful tool to probe the interface astrophysics, important for studying galactic ecosystems.

Keywords: x-ray observatories; spiral galaxies; high resolution spectroscopy; stellar feedback; diffuse radiation
Long-term Variations in the Orbital Period of Hot Jupiters from Transit-timing Analysis Using TESS Survey Data

Many hot Jupiters may experience orbital decays, which are manifested as long-term transit-timing variations. We have analyzed 7068 transits from the Transiting Exoplanet Survey Satellite (TESS) for a sample of 326 hot Jupiters. These new mid-transit-time data allow us to update ephemerides for these systems. By combining the new TESS transit-timing data with archival data, we searched for possible long-term variations in the orbital period in these hot Jupiters using a linear and a quadratic ephemeris model. We identified 26 candidates that exhibit possible long-term variations of the orbital period, including 18 candidates with decreasing orbital periods and eight candidates with increasing orbital periods. Among them, 12 candidates failed our leave-one-out cross validation test and thus should be considered to be marginal candidates. In addition to tidal interaction, alternative mechanisms such as apsidal precession, the Rømer effect, and the Applegate effect could also contribute to the variations during the observed period. The ephemerides derived in this work are useful for scheduling follow-up observations for these hot Jupiters in the future. The Python code (PdotQuest, https://github.com/AeoN400/PdotQuest) used to generate the ephemerides is made available online.

Keywords: hot jupiters; transit timing variation method; transit photometry
Spin-Orbit Resonances of High-eccentricity Asteroids: Regular, Switching, and Jumping

Few solar system asteroids and comets are found in high-eccentricity orbits (e > 0.9), but in the primordial planetesimal disks and in exoplanet systems around dying stars such objects are believed to be common. For 2006 HY51, the main belt asteroid with the highest known eccentricity 0.9684, we investigate the probable rotational states today using our computer-efficient chaotic process simulation method. Starting with random initial conditions, we find that this asteroid is inevitably captured into stable spin-orbit resonances typically within tens to a hundred megayears. The resonances are confirmed by direct integration of the equation of motion in the vicinity of endpoints. Most resonances are located at high spin values above 960 times the mean motion (such as 964:1 or 4169:4), corresponding to rotation periods of a few days. We discover three types of resonance in the high-eccentricity regime: (1) regular circulation with weakly librating aphelion velocities and integer-number spin-orbit commensurabilities, (2) switching resonances of higher order with orientation alternating between aligned (0 or π) and sidewise (π/2) angles at aphelia and perihelia, (3) jumping resonances with aphelion spin alternating between two quantum states in the absence of spin-orbit commensurability. The islands of equilibrium are numerous at high spin rates but small in parameter space area, so that it takes millions of orbits of chaotic wandering to accidentally entrap in one of them. We discuss the implications of this discovery for the origins and destiny of high-eccentricity objects and the prospects of extending this analysis to the full 3D treatment.

Keywords: eccentricity; asteroids; orbital resonances
Measuring the Orbits of the Arches and Quintuplet Clusters Using HST and Gaia: Exploring Scenarios for Star Formation near the Galactic Center

We present new absolute proper-motion measurements for the Arches and Quintuplet clusters, two young massive star clusters near the Galactic center. Using multiepoch HST observations, we construct proper-motion catalogs for the Arches (~35,000 stars) and Quintuplet (~40,000 stars) fields in ICRF coordinates established using stars in common with the Gaia EDR3 catalog. The bulk proper motions of the clusters are measured to be (μ α*, μ δ ) = (-0.80 ± 0.032, -1.89 ± 0.021) mas yr-1 for the Arches and (μ α*, μ δ ) = (-0.96 ± 0.032, -2.29 ± 0.023) mas yr-1 for the Quintuplet, achieving ≳5× higher precision than past measurements. We place the first constraints on the properties of the cluster orbits that incorporate the uncertainty in their current line-of-sight distances. The clusters will not approach closer than ~25 pc to Sgr A*, making it unlikely that they will inspiral into the nuclear star cluster within their lifetime. Further, the cluster orbits are not consistent with being circular; the average value of r apo/r peri is ~1.9 (equivalent to an eccentricity of ~0.31) for both clusters. Lastly, we find that the clusters do not share a common orbit, challenging one proposed formation scenario in which the clusters formed from molecular clouds on the open stream orbit derived by Kruijssen et al. Meanwhile, our constraints on the birth location and velocity of the clusters offer mild support for a scenario in which the clusters formed via collisions between gas clouds on the x 1 and x 2 bar orbit families.

Keywords: galactic center; young star clusters; star formation; astrometry
First Peek with JWST/NIRCam Wide-field Slitless Spectroscopy: Serendipitous Discovery of a Strong [O III]/Hα Emitter at z = 6.11

We report the serendipitous discovery of an [O III] λ λ4959/5007 and Hα line emitter in the Epoch of Reionization (EoR) with the James Webb Space Telescope (JWST) commissioning data taken in the NIRCam wide-field slitless spectroscopy (WFSS) mode. Located ~55″ away from the flux calibrator P330-E, this galaxy exhibits bright [O III] λ λ4959/5007 and Hα lines detected at 3.7σ, 9.9σ, and 5.7σ, respectively, with a spectroscopic redshift of z = 6.112 ± 0.001. The total Hβ+[O III] equivalent width is 664 ± 98 Å (454 ± 78 Å from the [O III] λ5007 line). This provides direct spectroscopic evidence for the presence of strong rest-frame optical lines (Hβ+[O III] and Hα) in EoR galaxies as inferred previously from the analyses of the Spitzer/IRAC spectral energy distributions (SEDs). Two spatial and velocity components are identified in this source, possibly indicating that this system is undergoing a major merger, which might have triggered the ongoing starburst with strong nebular emission lines over a timescale of ~2 Myr, as our SED modeling suggests. The tentative detection of He II λ4686 line (1.9σ), if real, may indicate the existence of very young and metal-poor star-forming regions with a hard UV radiation field. Finally, this discovery demonstrates the power and readiness of the JWST/NIRCam WFSS mode, and marks the beginning of a new era for extragalactic astronomy, in which EoR galaxies can be routinely discovered via blind slitless spectroscopy through the detection of rest-frame optical emission lines.

Keywords: emission line galaxies; high-redshift galaxies; starburst galaxies; galaxy spectroscopy; space telescopes; james webb space telescope
A Theory for the Maximum Magnitude versus Rate of Decline Relation of Classical Novae

We propose a theory for the maximum magnitude versus rate of decline (MMRD) relation of novae using free-free emission model light curves built on the optically thick wind theory. We calculated $({t}_{3},{M}_{V,\max })$ for various sets of $({\dot{M}}_{\mathrm{acc}},{M}_{\mathrm{WD}})$ , where ${M}_{V,\max }$ is the peak absolute V magnitude, t3 is the 3 mag decay time from the peak, and ${\dot{M}}_{\mathrm{acc}}$ is the mass accretion rate onto the white dwarf (WD) of mass MWD. The model light curves are uniquely characterized by $x\equiv {M}_{\mathrm{env}}/{M}_{\mathrm{sc}}$ , where Menv is the hydrogen-rich envelope mass and Msc is the scaling mass at which the wind has a certain wind mass-loss rate. For a given ignition mass Mig, we can specify the first point ${x}_{0}={M}_{\mathrm{ig}}/{M}_{\mathrm{sc}}$ on the model light curve and calculate the corresponding peak brightness and t3 time from this first point. Our $({t}_{3},{M}_{V,\max })$ points cover well the distribution of existing novae. The lower the mass accretion rate, the brighter the peak. The maximum brightness is limited to ${M}_{V,\max }\gtrsim -10.4$ by the lowest mass accretion rate of ${\dot{M}}_{\mathrm{acc}}\gtrsim 1\times {10}^{-11}\,{M}_{\odot }$ yr-1. A significant part of the observational MMRD trend corresponds to the ${\dot{M}}_{\mathrm{acc}}\sim 5\times {10}^{-9}\,{M}_{\odot }$ yr-1 line with different WD masses. A scatter from the trend line indicates a variation in their mass accretion rates. Thus, the global trend of an MMRD relation does exist, but its scatter is too large for it to be a precision distance indicator of individual novae.

Keywords: cataclysmic variable stars; classical novae; white dwarf stars; distance indicators; stellar winds
Evidence for a Dense, Inhomogeneous Circumstellar Medium in the Type Ia SNR 0519-69.0

We perform an expansion study of the Balmer-dominated outer shock of the SNR 0519-69.0 in the LMC by using a combination of new Hubble Space Telescope (HST) WFC3 imagery obtained in 2020 and archival ACS images from 2010 and 2011. Thanks to the very long time baseline, our proper motion measurements are of unprecedented accuracy. We find a wide range of shock velocities, with the fastest shocks averaging 5280 km s-1 and the slowest grouping of shocks averaging just 1670 km s-1. We compare the Hα images from HST with X-ray images from Chandra and mid-IR images from Spitzer, finding a clear anticorrelation between the brightness of the remnant in a particular location and the velocity of the blast wave at that location, supporting the idea that the bright knots of X-ray and IR emission result from an interaction with a dense inhomogeneous circumstellar medium. We find no evidence for X-ray emission, thermal or nonthermal, associated with the fastest shocks, as expected if the fastest velocities are the result of the blast wave encountering the lower density ambient medium of the LMC. We derive an age of the remnant of ≤670 ± 70 yr, consistent with results derived from previous investigations.

Keywords: supernova remnants; circumstellar matter; type ia supernovae; proper motions
The End of Galaxy Surveys

For nearly a century, imaging and spectroscopic surveys of galaxies have given us information about the contents of the universe. We attempt to define the logical end point of such surveys by defining not the next galaxy survey but rather the final galaxy survey at near-infrared wavelengths; this would be the galaxy survey that exhausts the information content useful for addressing extant questions. Such a survey would require incredible advances in a number of technologies, and the survey details will depend on the as yet poorly constrained properties of the earliest galaxies. Using an exposure time calculator, we define nominal surveys for extracting the useful information for three science cases: dark energy cosmology, galaxy evolution, and supernovae (SN). We define scaling relations that trade off sky background, telescope aperture, and focal plane size to allow for a survey of a given depth over a given area. For optimistic assumptions, a 280 m telescope with a marginally resolved focal plane of 20 deg2 operating at L2 could potentially exhaust the cosmological information content of galaxies in a 10 yr survey. For galaxy evolution (making use of gravitational lensing to magnify the earliest galaxies) and SN, the same telescope would suffice. We discuss the technological advances needed to complete the last galaxy survey. While the final galaxy survey remains well outside of our technical reach today, we present scaling relations that show how we can progress toward the goal of exhausting the information content encoded in the shapes, positions, and colors of galaxies.

Keywords: cosmology; galaxy evolution; supernovae; astronomical instrumentation; optical telescopes
Evolution of an Asteroid Family under YORP, Yarkovsky, and Collisions

Any population of asteroids, like asteroid families, will disperse in semimajor axis due to the Yarkovsky effect. The amount of drift is modulated by the asteroid spin state evolution, which determines the balance between the diurnal and seasonal Yarkovsky forces. The asteroid's spin state is, in turn, controlled in part by the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect. The otherwise smooth evolution of an asteroid can be abruptly altered by collisions, which can cause impulsive changes in the spin state and can move the asteroid onto a different YORP track. In addition, collisions may also alter the YORP parameters by changing the superficial features and overall shape of the asteroid. Thus, the coupling between YORP and Yarkovsky is also strongly affected by the impact history of each body. To investigate this coupling, we developed a statistical code modeling the time evolution of semimajor axis under YORP-Yarkovsky coupling. It includes the contributions of NYORP (normal YORP), TYORP (tangential YORP), and collisions whose effects are deterministically calculated and not added in a statistical way. We find that both collisions and TYORP increase the dispersion of a family in semimajor axis by making the spin axis evolution less smooth and regular. We show that the evolution of a family's structure with time is complex and collisions randomize the YORP evolution. In our test families, we do not observe the formation of a "YORP-eye" in the semimajor axis versus diameter distribution, even after a long period of time. If present, the "YORP-eye" might be a relic of an initial ejection velocity pattern of the collisional fragments.

Keywords: asteroids; main belt asteroids
The Infrared Variability of V1647 Ori over 26 yr with Spitzer, (NEO)WISE, and ISO

Outbursts from young Class 0 protostars are now being detected using 3–5 μm light curves assembled from Spitzer and WISE/NEOWISE photometry. For comparison, we present a 4–8 μm light curve of the erupting, more evolved protostar V1647 Ori (HOPS 388), assembled from photometry obtained with the ISOCAM camera on ISO, the IRAC camera on Spitzer, and from WISE and NEOWISE. Covering 26 yr, this light curve spans the longest available time interval from infrared space-based telescopes capable of separating individual young stellar objects in nearby molecular clouds. This curve does not include a two year interval where the visible-light photometry shows a large drop in brightness. In the case of V1647 Ori, we find that the increase in brightness (3.1 mag) and duration (16 yr) are similar to infrared (3–5 μm) outbursts found toward Class 0 protostars in Orion.

Keywords: young stellar objects; variable stars; star formation; infrared astronomy
The MKID Pipeline: A Data Reduction and Analysis Pipeline for UVOIR MKID Data

We present the Microwave Kinetic Inductance Detector (MKID) Pipeline, which is a general use science data pipeline for the reduction and analysis of ultraviolet, optical, and infrared MKID data sets. This paper provides an introduction to the nature of MKID data sets, it gives an overview of the calibration steps that are included in the pipeline, and it introduces the implementation of the software.

Keywords: publicly available software; astronomy data reduction; time series analysis
Impact of the Rotation and Compactness of Progenitors on the Mass of Black Holes

We investigate the impact of stellar rotation on the formation of black holes (BHs) by means of our population synthesis code SEVN. Rotation affects the mass function of BHs in several ways. In massive metal-poor stars, fast rotation reduces the minimum zero-age main sequence (ZAMS) mass for a star to undergo pair instability and pulsational pair instability. Moreover, stellar winds are enhanced by rotation, peeling off the entire hydrogen envelope. As a consequence of these two effects, the maximum BH mass we expect from the collapse of a rotating metal-poor star is only ∼45 M ⊙, while the maximum mass of a BH born from a nonrotating star is ∼60 M ⊙. Furthermore, stellar rotation reduces the minimum ZAMS mass for a star to collapse into a BH from ∼18-25 M ⊙ to ∼13-18 M ⊙. Finally, we have investigated the impact of different core-collapse supernova (CCSN) prescriptions on our results. While the threshold value of compactness for direct collapse and the fallback efficiency strongly affect the minimum ZAMS mass for a star to collapse into a BH, the fraction of the hydrogen envelope that can be accreted onto the final BH is the most important ingredient in determining the maximum BH mass. Our results confirm that the interplay between stellar rotation, CCSNe and pair instability plays a major role in shaping the BH mass spectrum.

Keywords: astrophysical black holes; stellar mass black holes; stellar mass loss; computational methods; gravitational wave astronomy; massive stars
PEARLS: Low Stellar Density Galaxies in the El Gordo Cluster Observed with JWST

A full understanding of how unusually large ultradiffuse galaxies (UDGs) fit into our conventional theory of galaxy formation remains elusive, despite the large number of objects identified locally. A natural extension of UDG research is the study of similar galaxies at higher redshift to establish how their properties may evolve over time. However, this has been a challenging task given how severely systematic effects and cosmological surface brightness dimming inhibit our ability to analyze low surface brightness galaxies at high z. Here, we present a sample of low stellar surface density galaxies (LDGs) at moderate redshift, likely the progenitors of local UDGs, identified using deep near-IR observations of the El Gordo cluster at z = 0.87 with JWST. By stacking eight NIRCAM filters, we reach an apparent surface brightness sensitivity of 24.59 mag arcsec-2, which is faint enough to be complete to the bright end of the LDG population. Our analysis identifies significant differences between this population and UDGs observed locally, such as their color and size distributions, which suggest that the UDG progenitors at high z are bluer and more extended than UDGs at z = 0. This suggests that multiple mechanisms are responsible for the UDG formation and that prolonged transformation of cluster dwarfs is not a primary UDG formation mechanism at high z. Furthermore, we find a slight overabundance of LDGs in El Gordo, and, in contrast to findings in local clusters, our analysis does not show a deficit of LDGs in the center of El Gordo, implying that tidal destruction of LDGs is significant between z = 0.87 and z = 0.

Keywords: low surface brightness galaxies; galaxy clusters; galaxy evolution; james webb space telescope; stellar populations; galaxy structure
Growth of Stellar-mass Black Holes in Dense Molecular Clouds and GW190521

A stellar-mass black hole can grow its mass noticeably through Bondi accretion, if it is embedded in an extremely dense and massive molecular cloud with slow motion with respect to the ambient medium for an extended period of time. This provides a novel, yet challenging channel for the formation of massive stellar-mass black holes. We discuss how this channel may account for the massive binary black hole merger system GW190521 as observed by LIGO/Virgo gravitational wave detectors as well as the claimed massive black hole candidate LB-1.

Keywords: black holes; bondi accretion; gravitational waves