adsabs/SciX_UAT_keywords huggingface dataset:
Characterization of a Solar Mass Eclipsing Binary with TESS and IGRINS

Stellar radius measurements from eclipsing binaries are typically ~5% larger than standard stellar models predict. This disagreement means we are unable to derive reliable model-dependent radii, which impact stellar and exoplanet characterization. Using light curves from the TESS satellite and high-resolution, near-infrared spectra from IGRINS, we determine the masses and radii of a main sequence eclipsing binary, V1177 Cen (TIC 3099339). We detrend the light curve using a Gaussian process and derive radial velocities using spectral-line broadening functions, fitting both jointly in an MCMC framework. We find that both stars are near 1 M ⊙ with radii 6%-9% larger than the Sun. Based on the absence of Lithium in optical spectra, the inflation is potentially the effect of early post-main sequence evolution, or magnetic fields. We compare our measurement to model isochrones, finding the most consistent agreement with models that include magnetic fields, and correspond to an age of ~4 Gyr.

Keywords: eclipsing binary stars
The Volumetric Star Formation Law in the Almost Edge-on Galaxy NGC 4302 Revealed by the Atacama Large Millimeter/submillimeter Array

We observe the almost edge-on (i ~ 90°) galaxy NGC 4302 using the Atacama Large Millimeter/submillimeter Array (CO) and Very Large Array (H I) to measure the gas disk thickness for investigating the volumetric star formation law (SFL). The recent star formation rate (SFR) is estimated based on a linear combination of IR 24 μm and Hα emissions. The measured scale heights of CO and H I increase significantly with radius. Using the scale heights along with the vertically integrated surface densities, we derive the midplane volume densities of the gas (ρ H I, ${\rho }_{{{\rm{H}}}_{2}}$ , and ρ gas = ρ H I+ ${\rho }_{{{\rm{H}}}_{2}}$ ) and the SFR (ρ SFR) and compare the volumetric SFL (ρ SFR ∝ ρ gas n) with the vertically integrated SFL (ΣSFR ∝ Σgas N). We find tight power-law correlations between the SFR and the gas (H I, H2, and the total gas) in both volume and surface densities. The power-law indices of the total gas and H I for the volumetric SFL are noticeably smaller than the indices for the vertically integrated SFL while the H2 indices for both cases are similar to each other. In terms of the star formation efficiency (SFE), we find that the molecular and total gas SFEs are roughly constant, while the atomic SFE is clearly decreasing with radius in both cases.

Keywords: radio astronomy; galaxy dynamics; galaxy kinematics; galaxy structure; bipolar sunspot groups; barred spiral galaxies; interstellar medium
The Nature of Low-surface-brightness Galaxies in the Hyper Suprime-Cam Survey

We present the statistical redshift distribution of a large sample of low-surface-brightness (LSB) galaxies identified in the first 200 deg2 of the Hyper Suprime-Cam Strategic Survey Program. Through cross-correlation with the NASA-SDSS Atlas, we find that the majority of objects lie within z < 0.15 or ~500 Mpc, yielding a mass range of M * ≈ 107-109 M ⊙ and a size range of r eff,g ≈ 1-8 kpc. We find a peak in the distance distribution within 100 Mpc, corresponding mostly to ~107 M ⊙ galaxies that fall on the known mass-size relation. There is also a tail in the redshift distribution out to z ≈ 0.15, comprising more massive (M * = 108 - 109 M ⊙) galaxies at the larger end of our size range. We see tentative evidence that at the higher-mass end (M * > 108 M ⊙), the LSB galaxies do not form a smooth extension of the mass-size relation of higher-surface-brightness galaxies, perhaps suggesting that the LSB galaxy population is distinct in its formation path.

Keywords: low surface brightness galaxies
GeV Gamma-Ray Emission and Molecular Clouds toward Supernova Remnant G35.6-0.4 and the TeV Source HESS J1858+020

It is difficult to distinguish the hadronic process from the leptonic one in γ-ray observation, which is however crucial in revealing the origin of cosmic rays. As an endeavor in this regard, we focus in this work on the complex γ-ray emitting region, which partially overlaps with the unidentified TeV source HESS J1858+020 and includes supernova remnant (SNR) G35.6-0.4 and H II region G35.6-0.5. We reanalyze CO line, H I, and Fermi-LAT GeV γ-ray emission data of this region. The analysis of the molecular and H I data suggests that SNR G35.6-0.4 and H II region G35.6-0.5 are located at different distances. The analysis of the GeV γ-rays shows that GeV emission arises from two point sources: one (SrcA) coincident with the SNR, and the other (SrcB) coincident with both HESS J1858+020 and H II region G35.6-0.5. The GeV emission of SrcA can be explained by the hadronic process in the SNR-molecular cloud association scenario. The GeV-band spectrum of SrcB and the TeV-band spectrum of HESS J1858+020 can be smoothly connected by a power-law function, with an index of ~2.2. The connected spectrum is well explained with a hadronic emission, with the cutoff energy of protons above 1 PeV. It thus indicates that there is a potential PeVatron in the H II region and should be further verified with ultrahigh-energy observations with, e.g., LHAASO.

Keywords: supernova remnants; gamma-rays; gamma-ray sources; molecular clouds
Observations of Bright Pulses from Pulsar B0031-07 at 4.82 GHz

We report on the detection of 146 (0.96%) bright pulses with a peak flux density >0.86 Jy from PSR B0031-07 in 4 hr of continuous observations made at 4.82 GHz, with a bandwidth of 1 GHz, using the Shanghai Tian Ma 65 m radio telescope. We find that the peak flux density distribution follows a power law with index α = -3.6 ± 0.2, while the pulse energy appears to follow a logarithmic normal distribution. The bright pulses from PSR B0031-07 were observed to repeat in an irregular fashion. The intervals between bright pulses can be described with an exponentiated Weibull distribution. Furthermore, the sensitive observations at higher frequency with a short time resolution of 65.54 μs form a reliable basis for detailed microstructure studies. Close inspection of the detected bright pulses reveals that 38 pulses exhibit well-defined quasi-periodicities. No unanimous period for the quasi-periodicities is found, and the peak flux density is independent of the micropulse width. Finally, possible physical mechanisms are discussed.

Keywords: radio pulsars
Observational Properties of 155 O- and B-type Massive Pulsating Stars

O- and B-type (OB-type) pulsating stars are important objects for studying the structure and evolution of massive stars through asteroseismology. A large amount of data from various sky surveys provides an unprecedented opportunity to search for and study this kind of variable star. We identify 155 OB-type pulsating stars or candidates, including 38 Oe/Be stars or candidates, from the data observed by TESS, LAMOST, and Gaia, which are almost new. Among the 155 objects, 87 samples are identified as slowly pulsating B (SPB) stars including 37 objects with pure low-frequency and 50 objects with both low- and high-frequency pulsation, and 14 samples are identified as β Cephei pulsating variable (BCEP) stars with both low- and high-frequency pulsation. An H-R diagram shows that these SPB and BCEP stars are mainly located in their instability regions and in the evolutionary stage of the main sequence with mass ranges of 2.5-20 M ⊙ and 7-20 M ⊙, respectively. Two special objects show Fourier spectra similar to BCEP stars but with different positions in H-R, period-temperature (P-T), and period-luminosity (P-L) diagrams. Meanwhile, 52 other targets are identified as candidates of OB-type pulsating stars. We also derive the preliminary results of the P-L relation for SPB and BCEP stars, respectively. This work also indicates that in addition to the H-R diagram, the P-T and P-L diagrams are also very useful for the classification of SPB and BCEP stars. Further detailed analysis of these objects can dramatically increase our understanding of the theories of evolution and structure for massive OB-type pulsating stars.

Keywords: pulsating variable stars; massive stars
Recurrent Galactic Cosmic-Ray Flux Modulation in L1 and Geomagnetic Activity during the Declining Phase of the Solar Cycle 24

Short-term variations (<1 month) of the galactic cosmic-ray (GCR) flux in the inner heliosphere are mainly associated with the passage of high-speed solar wind streams (HSS) and interplanetary (IP) counterparts of coronal mass ejections (ICMEs). Data gathered with a particle detector flown on board the ESA LISA Pathfinder (LPF) spacecraft, during the declining part of solar cycle 24 (2016 February-2017 July) around the Lagrange point L1, have allowed us to study the characteristics of recurrent cosmic-ray flux modulations above 70 MeV n-1. It is shown that the amplitude and evolution of individual modulations depend in a unique way on both IP plasma parameters and particle flux intensity before HSS and ICME transit. By comparing the LPF data with those gathered contemporaneously with the magnetic spectrometer experiment AMS-02 on board the International Space Station and with those of Earth's polar neutron monitors, the GCR flux modulation was studied at different energies during recurrent short-term variations. It is also aimed to set the near real-time particle observation requirements to disentangle the role of long- and short-term variations of the GCR flux to evaluate the performance of high-sensitivity instruments in space such as the future interferometers for gravitational wave detection. Finally, the association between recurrent GCR flux variation observations in L1 and weak to moderate geomagnetic activity in 2016-2017 is discussed. Short-term recurrent GCR flux variations are good proxies of recurrent geomagnetic activity when the Bz component of the IP magnetic field is directed north.

Keywords: cosmic ray detectors; interferometers; interplanetary medium; solar-terrestrial interactions; heliosphere; solar rotation
Novel Fiducial Fiber Scanning Measurement Method Based on a Polar Coordinate System for LAMOST

The multiobject fiber-fed spectrograph is the core scientific instrument for large-scale spectroscopic surveys. For closed-loop control of fiber positioning, fiber metrology systems are implemented in numerous fiber-fed spectrographs. The position accuracy of the fiducial fiber in the focal plate directly affects the performance of the fiber metrology system. However, there are currently no suitable methods and devices for measuring the fiducial fibers with high accuracy in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). To solve this problem, this study proposed a novel online scanning measurement method for fiducial fibers in which a scanning camera was set up in front of the focal plate, and the rotation and translation movements of the focal plate were combined to set a polar coordinate measurement system. First, the pole and polar axis of the polar coordinate frame were determined, and the compensation values of the polar radius and angle of the polar coordinate of the fiducial fibers were solved in the field of view of the scanning camera. A prototype measurement platform was set up to verify the feasibility and scientific validity of the method. Experiment results show that the polar radius accuracy of the proposed method met the measurement requirements. The X-Y measurement accuracy can be further improved when a higher-precision rotary stage is adopted. Thus, the difficulties in online accurate measurement for fiducial fibers can be tackled by the proposed method with good operability in LAMOST.

Keywords: astronomical techniques; astronomical instrumentation
Molecular Line Observations in Two Dusty Star-forming Galaxies at z = 6.9

SPT0311-58 is the most massive infrared luminous system discovered so far during the Epoch of Reionization (EoR). In this paper, we present a detailed analysis of the molecular interstellar medium at z = 6.9, through high resolution observations of the CO(6-5), CO(7-6), CO(10-9), [C I](2-1), and p-H2O(21,1 -20,2) lines and dust continuum emissions with the Atacama Large Millimeter/submillimeter Array. The system consists of a pair of intensely star-forming, gravitationally lensed galaxies (labeled West and East). The intrinsic far-infrared luminosity is (16 ± 4) × 1012 L⊙ in West and (27 ± 4) × 1011 L⊙ in East. We model the dust, CO, and [C I] using non-local thermodynamic equilibrium radiative transfer models and estimate the intrinsic gas mass to be (5.4 ± 3.4) × 1011 M⊙ in West and (3.1 ± 2.7) × 1010 M⊙ in East. We find that the CO spectral line energy distribution in West and East are typical of high-redshift submillimeter galaxies (SMGs). The CO-to-H2 conversion factor (αCO) and the gas depletion timescales estimated from the model are consistent with the high-redshift SMGs in the literature within the uncertainties. We find no evidence of evolution of depletion time with redshift in SMGs at z > 3. This is the most detailed study of molecular gas content of a galaxy in the EoR to date, with the most distant detection of H2O in a galaxy without any evidence for active galactic nuclei in the literature.

Keywords: high-redshift galaxies; starburst galaxies; ultraluminous infrared galaxies
Characterization of High-priority Landing Sites for Robotic Exploration Missions in the Apollo Basin, Moon

The South Pole–Aitken (SPA) basin is the oldest and largest visible impact structure on the Moon, making it a high priority science site for exploration missions. The 492 km diameter Apollo peak-ring basin is one of the youngest and largest basins within the SPA basin. We selected three regions of interest (ROIs) in the Apollo basin for which the landing and operational hazards are minimized and evaluated their science and in situ resource utilization (ISRU) potential. We examined topography, slope, crater density, rock abundance, geologic mapping, mineralogy, and inferred subsurface stratigraphy within each ROI. The results show that the terrain is safe for landing without precision landing (within a few hundred meters). The mare materials have high ISRU potential with relatively high FeO (∼16–20 wt%) and TiO2 (∼3–10 wt%) contents. Two robotic exploration mission architectures were examined for their scientific potential: (1) lander and rover with a dedicated payload suite and (2) the same architecture with sample return capability. In situ observations can address six of seven National Research Council concepts (1–3, 5–7) and Campaigns 1 and 5 of the European Space Agency's Strategy for Science at the Moon.

Keywords: the moon; lunar science
The Occurrence of Rocky Habitable-zone Planets around Solar-like Stars from Kepler Data

We present the occurrence rates for rocky planets in the habitable zones (HZs) of main-sequence dwarf stars based on the Kepler DR25 planet candidate catalog and Gaia-based stellar properties. We provide the first analysis in terms of star-dependent instellation flux, which allows us to track HZ planets. We define η⊕ as the HZ occurrence of planets with radii between 0.5 and 1.5 R⊕ orbiting stars with effective temperatures between 4800 and 6300 K. We find that η⊕ for the conservative HZ is between ${0.37}_{-0.21}^{+0.48}$ (errors reflect 68% credible intervals) and ${0.60}_{-0.36}^{+0.90}$ planets per star, while the optimistic HZ occurrence is between ${0.58}_{-0.33}^{+0.73}$ and ${0.88}_{-0.51}^{+1.28}$ planets per star. These bounds reflect two extreme assumptions about the extrapolation of completeness beyond orbital periods where DR25 completeness data are available. The large uncertainties are due to the small number of detected small HZ planets. We find similar occurrence rates between using Poisson likelihood Bayesian analysis and using Approximate Bayesian Computation. Our results are corrected for catalog completeness and reliability. Both completeness and the planet occurrence rate are dependent on stellar effective temperature. We also present occurrence rates for various stellar populations and planet size ranges. We estimate with 95% confidence that, on average, the nearest HZ planet around G and K dwarfs is ∼6 pc away and there are ∼4 HZ rocky planets around G and K dwarfs within 10 pc of the Sun.

Keywords: exoplanets
A Subsolar Metallicity Progenitor for Cassiopeia A, the Remnant of a Type IIb Supernova

We report the detection of the Mn-Kα line in the SN-IIb remnant, Cassiopeia A. Manganese (55Mn after decay of 55Co), a neutron-rich element, together with chromium (52Cr after decay of 52Fe), is mainly synthesized in core-collapse supernovae at the explosive incomplete Si-burning regime. Therefore, the Mn/Cr mass ratio with its neutron excess reflects the neutronization at the relevant burning layer during the explosion. Chandra's deep archival X-ray data of Cassiopeia A indicate a low Mn/Cr mass ratio with values in the range 0.10-0.66, which, when compared to one-dimensional SN explosion models, requires that the electron fraction be 0.4990 ≲ Ye ≲ 0.5 at the incomplete Si-burning layer. An explosion model assuming a solar-metallicity progenitor with a typical explosion energy (1 × 1051 erg) fails to reproduce such a high electron fraction. We can satisfy the observed Mn/Cr mass ratio if the explosive Si-burning regime was to extend into the O/Ne hydrostatic layer, which has a higher Ye. This would require an energetic (>2 × 1051 erg) and/or asymmetric explosion of a subsolar-metallicity progenitor (Z ≲ 0.5Z⊙) for Cassiopeia A. The low initial metallicity can be used to rule out a single-star progenitor, leaving the possibility of a binary progenitor with a compact companion. We discuss the detectability of X-rays from Bondi accretion onto such a compact companion around the explosion site. We also discuss other possible mass-loss scenarios for the progenitor system of Cassiopeia A.

Keywords: x-ray astronomy; supernova remnants; nucleosynthesis; stellar evolution; core-collapse supernovae
New Determination of the 12C(α, γ)16O Reaction Rate and Its Impact on the Black-hole Mass Gap

We present a precise measurement of the asymptotic normalization coefficient (ANC) for the 16O ground state (GS) through the 12C(11B, 7Li)16O transfer reaction using the Quadrupole‑3‑Dipole (Q3D) magnetic spectrograph. The present work sheds light on the existing discrepancy of more than 2 orders of magnitude between the previously reported GS ANC values. This ANC is believed to have a strong effect on the 12C(α, γ)16O reaction rate by constraining the external capture to the 16O ground state, which can interfere with the high-energy tail of the 2+ subthreshold state. Based on the new ANC, we determine the astrophysical S-factor and the stellar rate of the 12C(α, γ)16O reaction. An increase of up to 21% in the total reaction rate is found within the temperature range of astrophysical relevance compared with the previous recommendation of a recent review. Finally, we evaluate the impact of our new rate on the pair-instability mass gap for black holes (BH) by evolving massive helium core stars using the MESA stellar evolution code. The updated 12C(α, γ)16O reaction rate decreases the lower and upper edges of the BH gap about 12% and 5%, respectively.

Keywords: black holes; nuclear astrophysics; nuclear physics; massive stars; astrophysical black holes
The Wide-field VLBA Calibrator Survey: WFCS

This paper presents the results of the largest very long baseline interferometry (VLBI) absolute astrometry campaign to date of 13,645 radio source observations with the Very Long Baseline Array. Of these, 7220 have been detected, including 6755 target sources that have never been observed with VLBI before. This makes the present VLBI catalog the largest ever published. The positions of the target sources have been determined with the median uncertainty of 1.7 mas, and 15,542 images of 7171 sources have been generated. Unlike previous absolute radio astrometry campaigns, observations were made at 4.3 and 7.6 GHz simultaneously using a single wide-band receiver. Because of the fine spectral and time resolutions, the field of view was 4'-8'—much greater than the 10″-20″ in previous surveys. This made possible the use of input catalogs with low position accuracy and the detection of a compact component in extended sources. Unlike previous absolute astrometry campaigns, both steep- and flat-spectrum sources were observed. The observations were scheduled in the so-called filler mode to fill the gaps between other high-priority programs. This was achieved by the development of the totally automatic scheduling procedure.

Keywords: radio astrometry; very long baseline interferometry; astronomical coordinate systems; astronomy data analysis; active galactic nuclei; radio source catalogs
Dust Grain Growth and Dusty Supernovae in Low-metallicity Molecular Clouds

We present 3D hydrodynamical models of the evolution of superbubbles powered by stellar winds and supernovae from young coeval massive star clusters within low-metallicity (Z = 0.02 Z ⊙), clumpy molecular clouds. We explore the initial stages of the superbubble evolution, including the occurrence of pair-instability and core-collapse supernovae. Our aim is to study the occurrence of dust grain growth within orbiting dusty clumps, and in the superbubble's swept-up supershell. We also aim to address the survival of dust grains produced by sequential supernovae. The model accounts for the star cluster gravitational potential and self-gravity of the parent cloud. It also considers radiative cooling (including that induced by dust) and a state-of-the-art population synthesis model for the coeval cluster. As shown before, a superbubble embedded into a clumpy medium becomes highly distorted, expanding mostly due to the hot gas streaming through low-density channels. Our results indicate that in the case of massive (~107 M ⊙) molecular clouds, hosting a super star cluster (~5.6 × 105 M ⊙), grain growth increments the dust mass at a rate ~4.8 × 10-5 M ⊙ yr-1 during the first 2.5 Myr of the superbubble's evolution, while the net contribution of pair-instability and core-collapse supernovae to the superbubble's dust budget is ~1200 M ⊙ (M SC/5.6 × 105 M ⊙), where M SC is the stellar mass of the starburst. Therefore, dust grain growth and dust injection by supernovae lead to the creation of, without invoking a top-heavy initial mass function, massive amounts of dust within low-metallicity star-forming molecular clouds, in accordance with the large dust mass present in galaxies soon after the onset of cosmic reionization.

Keywords: interstellar dust; young massive clusters; hydrodynamical simulations; molecular clouds; supernovae