adsabs/SciX_UAT_keywords huggingface dataset:
The Masses of Isolated Neutron Stars Inferred from the Gravitational Redshift Measurements

For some neutron stars (NSs) in the binary systems, the masses have been accurately measured. While for the isolated neutron stars (INSs), no mass measurement has been reported yet. The situation will change soon thanks to the successful performance of the Neutron Star Interior Composition Explorer (NICER), with which the radius and mass of the isolated PSR J0030+0451 can be simultaneously measured. For most INSs, no mass measurements are possible for NICER because of observational limitations. Benefiting from recent significant progress made on constraining the equation of state of NSs, in this work we propose a way to estimate the masses of the INSs with the measured gravitational redshifts. We apply our method to RX J1856.5-3754, RX J0720.4-3125, and RBS 1223, three members of “The Magnificent Seven” (M7), and estimate their masses to be {1.24}-0.29+0.29 {M}⊙ , {1.23}-0.05+0.10 {M}⊙ , and {1.08}-0.11+0.20 {M}⊙ , respectively. These masses are consistent with that of binary NS systems, suggesting no evidence for experiencing significant accretion of these isolated objects.

Keywords: single x-ray stars; gravitational waves; neutron stars; neutron star cores
A Knee Point in the Rotation-Activity Scaling of Late-type Stars with a Connection to Dynamo Transitions

The magnetic activity of late-type stars is correlated with their rotation rates. Up to a certain limit, stars with smaller Rossby numbers, defined as the rotation period divided by the convective turnover time, have higher activity. A more detailed look at this rotation-activity relation reveals that, rather than being a simple power-law relation, the activity scaling has a shallower slope for the low-Rossby stars than for the high-Rossby ones. We find that, for the chromospheric Ca II H&K activity, this scaling relation is well modeled by a broken two-piece power law. Furthermore, the knee point of the relation coincides with the axisymmetry to nonaxisymmetry transition seen in both the spot activity and surface magnetic field configuration of active stars. We interpret this knee point as a dynamo transition between dominating axi- and nonaxisymmetric dynamo regimes with a different dependence on rotation and discuss this hypothesis in the light of current numerical dynamo models.

Keywords: late-type stars; stellar activity; stellar magnetic fields; stellar rotation
Studying the Radio Eclipse of Spider Pulsar J1816+4510 with the FAST

We report on the radio eclipse properties of spider pulsar J1816+4510 using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The high-sensitivity FAST observations will allow us to probe much deeper into the eclipse region of this pulsar at higher frequencies >1 GHz. The duration of the full eclipse, eclipse ingress, and egress at 1100, 1200, 1300, and 1400 MHz are measured, respectively. The variation of eclipse duration with frequency is studied by splitting the FAST observations into four subbands. It is found that the eclipse egress of PSR J1816+4510 takes longer than the ingress and becomes more symmetrical with increasing frequency. The variations of the durations with the frequency for the full eclipse, eclipse ingress, and egress follow a power-law decay pattern with different indices. The pulse profile variations near the eclipse are studied. It is found that the broadening of pulse profiles becomes more prominent with deepening into the eclipse region due to the scattering from the companion star. Moreover, the pulse smearing induced by the scattering and the rapid dispersion measure (DM) fluctuations within a subintegration during the eclipse egress at different frequencies and orbital phases is comparatively studied. It is found that the scattering plays a more important role than the DM fluctuations for the pulse smearing of the eclipse. The observations of this paper will provide important clues for the theoretical studies of the radio eclipse mechanism of the spider pulsar systems.

Keywords: pulsars; rotation powered pulsars; radio pulsars
Gaia GraL: Gaia DR2 Gravitational Lens Systems. VI. Spectroscopic Confirmation and Modeling of Quadruply Imaged Lensed Quasars

Combining the exquisite angular resolution of Gaia with optical light curves and WISE photometry, the Gaia Gravitational Lenses group (GraL) uses machine-learning techniques to identify candidate strongly lensed quasars, and has confirmed over two dozen new strongly lensed quasars from the Gaia Data Release 2. This paper reports on the 12 quadruply imaged quasars identified by this effort to date, which is a ~20% increase in the total number of confirmed quadruply imaged quasars. We discuss the candidate selection, spectroscopic follow-up, and lens modeling. We also report our spectroscopic failures as an aid for future investigations.

Keywords: strong gravitational lensing; quasars
Detecting the Oscillation and Propagation of the Nascent Dynamic Solar Wind Structure at 2.6 Solar Radii Using Very Long Baseline Interferometry Radio Telescopes

Probing the solar corona is crucial to study the coronal heating and solar wind acceleration. However, the transient and inhomogeneous solar wind flows carry large-amplitude inherent Alfvén waves and turbulence, which make detection more difficult. We report the oscillation and propagation of the solar wind at 2.6 solar radii (Rs) by observation of China's Tianwen and ESA's Mars Express with radio telescopes. The observations were carried out on 2021 October 9, when one coronal mass ejection (CME) passed across the ray paths of the telescope beams. We obtain the frequency fluctuations (FFs) of the spacecraft signals from each individual telescope. First, we visually identify the drift of the frequency spikes at a high spatial resolution of thousands of kilometers along the projected baselines. They are used as traces to estimate the solar wind velocity. Then we perform the cross-correlation analysis on the time series of FF from different telescopes. The velocity variations of solar wind structure along radial and tangential directions during the CME passage are obtained. The oscillation of tangential velocity confirms the detection of a streamer wave. Moreover, at the tail of the CME, we detect the propagation of an accelerating fast field-aligned density structure indicating the presence of magnetohydrodynamic waves. This study confirms that the ground-station pairs are able to form particular spatial projection baselines with high resolution and sensitivity to study the detailed propagation of the nascent dynamic solar wind structure.

Keywords: solar wind; very long baseline interferometry; deep space probes
A Comparison of the Composition of Planets in Single-planet and Multiplanet Systems Orbiting M dwarfs

We investigate and compare the composition of M-dwarf planets in systems with only one known planet ("singles") to those residing in multiplanet systems ("multis") and the fundamental properties of their host stars. We restrict our analysis to planets with directly measured masses and radii, which comprise a total of 70 planets: 30 singles and 40 multis in 19 systems. We compare the bulk densities for the full sample, which includes planets ranging in size from 0.52 R ⊕ to 12.8 R ⊕, and find that single planets have significantly lower densities on average than multis, which we cannot attribute to selection biases. We compare the bulk densities normalized by an Earth model for planets with R p < 6 R ⊕ and find that multis are also denser with 99% confidence. We calculate and compare the core/water mass fractions (CMF/WMF) of low-mass planets (M p < 10 M ⊕) and find that the likely rocky multis (with R p < 1.6 R ⊕) have lower CMFs than singles. We also compare the [Fe/H] metallicity and rotation period of all single-planet versus multiplanet host stars with such measurements in the literature and find that multiplanet hosts are significantly more metal-poor than those hosting a single planet. Moreover, we find that the host star metallicity decreases with increasing planet multiplicity. In contrast, we find only a modest difference in the rotation period. The significant differences in planetary composition and metallicity of the host stars point to different physical processes governing the formation of single-planet and multiplanet systems in M dwarfs.

Keywords: exoplanet formation; exoplanet systems
Discovery of a Low-mass Comoving System Using NOIRLab Source Catalog DR2

We present the discovery of a low-mass comoving system found by means of the NOIRLab Source Catalog DR2. The system consists of the high proper-motion star LEHPM 5005 and an ultracool companion 2MASS J22410186-4500298 with an estimated spectral type of L2. The primary (LEHPM 5005) is likely a mid-M dwarf but over-luminous for its color, indicating a possible close equal mass binary. According to the Gaia EDR3 parallax of the primary, the system is located at a distance of 58 ± 2 pc. We calculated an angular separation of 7"2 between both components, resulting in a projected physical separation of 418 au.

Keywords: low mass stars; binary stars
Strong Calcium Emission Indicates that the Ultraviolet-flashing SN Ia 2019yvq Was the Result of a Sub-Chandrasekar-mass Double-detonation Explosion

We present nebular spectra of the Type Ia supernova (SN Ia) SN 2019yvq, which had a bright flash of blue and ultraviolet light after exploding, followed by a rise similar to other SNe Ia. Although SN 2019yvq displayed several other rare characteristics, such as persistent high ejecta velocity near peak brightness, it was not especially peculiar, and if the early "excess" emission were not observed, it would likely be included in cosmological samples. The excess flux can be explained by several different physical models linked to the details of the progenitor system and explosion mechanism. Each has unique predictions for the optically thin emission at late times. In our nebular spectra, we detect strong [Ca II] λλ7291, 7324 and Ca near-IR triplet emission, consistent with a double-detonation explosion. We do not detect H, He, or [O I] emission, predictions for some single-degenerate progenitor systems and violent white dwarf mergers. The amount of swept-up H or He is <2.8 × 10-4 and 2.4 × 10-4 M⊙, respectively. Aside from strong Ca emission, the SN 2019yvq nebular spectrum is similar to those of typical SNe Ia with the same light-curve shape. Comparing to double-detonation models, we find that the Ca emission is consistent with a model with a total progenitor mass of 1.15 M⊙. However, we note that a lower progenitor mass better explains the early light-curve and peak luminosity. The unique properties of SN 2019yvq suggest that thick He-shell double detonations only account for ${1.1}_{-1.1}^{+2.1} \% $ of the total "normal" SN Ia rate. The SN 2019yvq is one of the best examples yet that multiple progenitor channels appear necessary to reproduce the full diversity of "normal" SNe Ia.

Keywords: supernovae; observational astronomy; white dwarf stars; type ia supernovae
The Solar Wind at (16) Psyche: Predictions for a Metal World

NASA's Psyche spacecraft will carry a magnetometer to main-belt asteroid (16) Psyche to search for remanent magnetic fields, and to attempt electromagnetic sounding of the interior. However, the Psyche spacecraft does not carry an instrument to measure solar wind plasmas. We thus combine data from five missions that have measured the solar wind at the orbit of asteroid (16) Psyche. We characterize these upstream conditions for future modeling and reference. We consider the implications of these ambient conditions for the interaction between (16) Psyche and the solar wind, outlining four possible resulting magnetospheres. Any magnetosphere would be dominated by ion-scale (Hall) physics and exotic electron-scale physics, requiring sophisticated physical modeling to describe. Under these different regimes, plasma generates additional electromagnetic fields, resulting in complex magnetism which may complicate the magnetic environment near asteroid (16) Psyche. Future missions to asteroids would benefit from combined magnetic field and plasma measurements.

Keywords: solar wind; asteroid belt; planetary magnetospheres; main belt asteroids; asteroids; star-planet interactions; space plasmas; magnetic anomalies; magnetic fields
Transition from Ordered Pinched to Warped Magnetic Field on a 100 au Scale in the Class 0 Protostar B335

We present our observational results of the 0.87 mm polarized dust emission in the Class 0 protostar B335 obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) at a 0"2 (20 au) resolution. We compared our data at 0.87 mm with those at 1.3 mm from the ALMA archive. The observed polarization orientations at the two wavelengths are consistent within the uncertainty, and the polarization percentages are systematically higher at 1.3 mm than 0.87 mm by a factor of ∼1.7, suggesting that the polarized emission originates from magnetically aligned dust grains. We inferred the magnetic field orientations from the observed polarization orientations. We found that the magnetic field changes from ordered and highly pinched to more complicated and asymmetric structures within the inner 100 au scale of B335, and the magnetic field connects to the center along the equatorial plane as well as along the directions that are ∼40°-60° from the equatorial plane. We performed nonideal MHD simulations of collapsing dense cores. We found that similar magnetic field structures appear in our simulations of dense cores with the magnetic field and rotational axis slightly misaligned by 15° but not in those with the aligned magnetic field and rotational axis. Our results suggest that the midplane of the inner envelope within the inner 100 au scale of B335 could be warped because of the misaligned magnetic field and rotational axis, and the magnetic field could be dragged by the warped accretion flows.

Keywords: star formation; interstellar magnetic fields; interstellar dynamics; gravitational collapse; protostars; bok globules
KIC 2857323: A Double-mode High-amplitude δ Scuti Star with Amplitude Decline of the First Overtone Mode

We investigate the pulsating behavior of KIC 2857323 using high-precision observations from the Kepler mission. Fourier analysis of 4 yr time-series data reveals five independent frequencies for the light variation. Among them, two strong frequencies f 1 and f 3 with a period ratio of 0.774 identify this star as a double-mode (i.e., the fundamental mode F0 and first overtone mode F1) high-amplitude δ Scuti star (HADS). Seismic modeling using the two radial modes F0 and F1 indicates that KIC 2857323 is a main-sequence star with mass M = 1.78 ± 0.02 M ⊙ and metallicity Z from 0.009 to 0.012. We analyze the phase and amplitude variations of F0 and F1 using the phase modulation method and find that the first overtone mode F1 shows a slow decline in amplitude. We discuss several possible causes for the amplitude variation and speculate that the amplitude decline in this star may be due to pulsation energy loss. We note that KIC 2857323 is the first double-mode HADS to show amplitude decline and warrants further study to ascertain its nature.

Keywords: delta scuti variable stars; stellar evolution; asteroseismology
The Complex Rotational Light Curve of (385446) Manwë-Thorondor, a Multicomponent Eclipsing System in the Kuiper Belt

Kuiper Belt Object (385446) Manwë-Thorondor is a multiobject system with mutual events predicted to occur from 2014 to 2019. To detect the events, we observed the system at 4 epochs (UT 2016 August 25 and 26, 2017 July 22 and 25, 2017 November 9, and 2018 October 6) in g, r, and VR bands using the 4 m SOAR and the 8.1 m Gemini South telescopes at Cerro Pachón, Chile, and Lowell Observatory’s 4.3 m Discovery Channel Telescope at Happy Jack, Arizona. These dates overlap the uncertainty range (±0.5 day) for four inferior events (Thorondor eclipsing Manwë). We clearly observe variability for the unresolved system with a double-peaked period 11.88190 ± 0.00005 hr and ∼0.5 mag amplitude together with much longer-term variability. Using a multicomponent model, we simultaneously fit our observations and earlier photometry measured separately for Manwë and Thorondor with the Hubble Space Telescope. Our fit suggests Manwë is bilobed, close to the “barbell” shape expected for a strengthless body with density ∼0.8 g cm-3 in hydrostatic equilibrium. For Manwë, we thereby derive maximum width to length ratio ∼0.30, surface area equivalent to a sphere of diameter 190 km, geometric albedo 0.06, mass 1.4 × 1018 kg, and spin axis oriented ∼75° from Earth’s line of sight. Changes in Thorondor’s brightness by ∼0.6 mag with a ∼300 day period may account for the system’s long-term variability. Mutual events with unexpectedly shallow depth and short duration may account for residuals to the fit. The system is complex, providing a challenging puzzle for future modeling efforts.

Keywords: kuiper belt; light curves; small solar system bodies
Strongly Lensed Supernova Refsdal: Refining Time Delays Based on the Supernova Explosion Models

We explore the properties of supernova (SN) "Refsdal"—the first discovered gravitationally lensed SN with multiple images. A large magnification provided by the galactic-scale lens, augmented by the cluster lens, gave us a unique opportunity to perform a detailed modeling of a distant SN at $z\simeq 1.5$ . We present results of radiation hydrodynamics modeling of SN Refsdal. According to our calculations, the SN Refsdal progenitor is likely to be a more massive and energetic version of SN 1987A, i.e., a blue supergiant star with the following parameters: the progenitor radius ${R}_{0}=(50\pm 1){R}_{\odot }$ , the total mass ${M}_{\mathrm{tot}}=(25\pm 2){M}_{\odot }$ , the radioactive 56Ni mass ${M}_{{}^{56}\mathrm{Ni}}=(0.26\pm 0.05)\,{M}_{\odot }$ , and the total energy release ${E}_{\mathrm{burst}}=(4.7\pm 0.8)\times {10}^{51}$ erg. Reconstruction of SN light curves allowed us to obtain time delays and magnifications for the images S2-S4 relative to S1 with higher accuracy than previous template-based estimates of Rodney et al. (2016). The measured time delays are ${\rm{\Delta }}{t}_{S2-S1}={9.5}_{-2.7}^{+2.6}$ days, ${\rm{\Delta }}{t}_{S3-S1}={4.2}_{-2.3}^{+2.3}$ days, and ${\rm{\Delta }}{t}_{S4-S1}={30}_{-8.2}^{+7.8}$ days. The obtained magnification ratios are ${\mu }_{S2/S1}=1.14\pm 0.02$ , ${\mu }_{S3/S1}=1.01\pm 0.02$ , and ${\mu }_{S4/S1}=0.35\pm 0.02$ . We estimate the Hubble constant ${H}_{0}={68.6}_{-9.7}^{+13.6}$ km s-1 Mpc-1 via rescaling the time delays predicted by different lens models to match the values obtained in this work. With more photometric data on the fifth image SX, we will be able to further refine the time delay and magnification estimates for SX and obtain competitive constraints on H0.

Keywords: type ii supernovae; strong gravitational lensing; galaxy clusters
Visualizing Multiwavelength Properties of Classified X-Ray Sources from Chandra Source Catalog

We present a simple but informative online tool to visualize the multiwavelength (MW) properties of ≈2700 X-ray sources from Chandra Source Catalog version 2.0 with literature verified classifications. Here we describe the catalogs that we used to collect the classifications and extract the MW properties of these sources, and the properties themselves. We also describe the design and functionality of the tool.

Keywords: catalogs; surveys; x-ray astronomy; x-ray stars; x-ray active galactic nuclei; high mass x-ray binary stars; low-mass x-ray binary stars; neutron stars; cataclysmic variable stars; young stellar objects
The Sizes of z ∼ 9-10 Galaxies Identified in the Brightest of Reionizing Galaxies (BoRG) Survey

Redshift z = 9-10 object selection is the effective limit of Hubble Space Telescope (HST) imaging capability, even when confirmed with Spitzer. If only a few photometry data points are available, it becomes attractive to add criteria based on their morphology in these J- and H-band images. One could do so through visual inspection, a size criterion, or alternate morphometrics. We explore a vetted sample of Brightest of Reionizing Galaxies (BoRG) z ∼ 9 and z ∼ 10 candidate galaxies and the object rejected by Morishita+ to explore the utility of a size criterion in z = 9-10 candidate selection. A stringent, point-spread function (PSF)-corrected effective radius criterion ( ${r}_{e}\lt 0\buildrel{\prime\prime}\over{.} 3$ ) would result in the rejection of 65%-70% of the interlopers visually rejected by Morishita et al. It may also remove up to ∼20% of bona fide brightest ( $L\gg {L}^{* }$ ) z = 9 or 10 candidates from a BoRG selected sample based on the Mason et al. luminosity functions, assuming the Holwerda et al. $z\sim 9$ size-luminosity relation. We argue that including a size constraint in lieu of a visual inspection may serve in wide-field searches for these objects in, e.g., Euclid or HST archival imaging with the understanding that some brightest ( $L\gg {L}^{* }$ ) candidates may be missed. The sizes of the candidates found by Morishita et al. follow the expected size distribution of z ∼ 9 for bright galaxies, consistent with the log normal in Shibuya et al. and single objects. Two candidates show high star formation surface density ( ${{\rm{\Sigma }}}_{\mathrm{SFR}}\gt 25{M}_{\odot }\,{\mathrm{kpc}}^{-2}$ ) and all merit further investigation and follow-up observations.

Keywords: high-redshift galaxies; galaxies; lyman-break galaxies; galactic and extragalactic astronomy; galaxy classification systems; galaxy distances; galaxy evolution; galaxy radii; galaxy stellar content; galaxy formation
A Luminous Precursor in the Extremely Bright GRB 230307A

GRB 230307A is an extremely bright long-duration GRB with an observed gamma-ray fluence of ≳3 × 10-3 erg cm-2 (10-1000 keV), second only to GRB 221009A. Despite its long duration, it is possibly associated with a kilonova, thus resembling the case of GRB 211211A. In analogy with GRB 211211A, we distinguish three phases in the prompt gamma-ray emission of GRB 230307A: an initial short duration, spectrally soft emission; a main long duration, spectrally hard burst; and a temporally extended and spectrally soft tail. We interpret the initial soft pulse as a bright precursor to the main burst and compare its properties with models of precursors from compact binary mergers. We find that to explain the brightness of GRB 230307A, a magnetar-like (≳1015 G) magnetic field should be retained by the progenitor neutron star. Alternatively, in the postmerger scenario, the luminous precursor could point to the formation of a rapidly rotating massive neutron star.

Keywords: gamma-ray bursts; neutron stars; gravitational wave astronomy
Empirical Dust Attenuation Model Leads to More Realistic UVJ Diagram for TNG100 Galaxies

Dust attenuation varies substantially from galaxy to galaxy and as of yet cannot be reproduced from first principles in theoretical models. In Nagaraj et al., we developed the first Bayesian population model of dust attenuation as a function of stellar population properties and projected galaxy shape, built on spectral energy distribution fits of nearly 30,000 galaxies in the 3D-HST grism survey with broadband photometric coverage from the rest-frame UV to IR. In this paper, we apply the model, named "DustE," to galaxies from the large-volume cosmological simulation TNG100 at z = 1. We produce a UVJ diagram and compare it with one obtained in previous work by applying approximate radiative transfer to the simulated galaxies. We find that the UVJ diagram based on our empirical model is in better agreement with observations than the previous effort, especially in the number density of dusty star-forming galaxies. We also construct the intrinsic dust-free UVJ diagram for TNG100 and 3D-HST galaxies at z ~ 1, finding qualitative agreement but residual differences at the 10%-20% level. These differences may be caused by the finding that TNG100 galaxies have, on average, 29% younger stellar populations and possibly higher metallicities than observed galaxies.

Keywords: hierarchical models; galaxy evolution; spectral energy distribution; high-redshift galaxies