bluuebunny/crossref_metadata_2025_split huggingface dataset:
Large Photospheric Doppler Shift in Solar Active Region 12673. I. Field-aligned Flows
Authors: Liu 刘 Jiayi 嘉奕 , Sun 孙 Xudong 旭东 , Schuck Peter W. , Jaeggli Sarah A. , Welsch Brian T. , Quintero Noda C. 
Published: September 2023

Abstract
Delta (δ) sunspots sometimes host fast photospheric flows along the central magnetic polarity inversion line (PIL). Here we study the strong Doppler shift signature in the central penumbral light bridge of solar active region NOAA 12673. Observations from the Helioseismic and Magnetic Imager (HMI) indicate highly sheared and strong magnetic fields. Large Doppler shifts up to 3.2 km s−1 appeared during the formation of the light bridge and persisted for about 16 hr. A new velocity estimator, called DAVE4VMwDV, reveals fast converging and shearing motion along the PIL from HMI vector magnetograms, and recovers the observed Doppler signal much better than an old version of the algorithm. The inferred velocity vectors are largely (anti-)parallel to the inclined magnetic fields, suggesting that the observed Doppler shift contains a significant contribution from the projected field-aligned flows. High-resolution observations from the Hinode/Spectro-Polarimeter further exhibit a clear correlation between the Doppler velocity and the cosine of the magnetic inclination, which is in agreement with HMI results and consistent with a field-aligned flow of about 9.6 km s−1. The complex Stokes profiles suggest significant gradients of physical variables along the line of sight. We discuss the implications on the δ-spot magnetic structure and the flow-driving mechanism.
Orbital Support and Evolution of Flat Profiles of Bars (Shoulders)
Authors: Beraldo e Silva Leandro , Debattista Victor P. , Anderson Stuart Robert , Valluri Monica , Erwin Peter , Daniel Kathryne J. , Deg Nathan 
Published: September 2023

Abstract
Many barred galaxies exhibit upturns (shoulders) in their bar-major-axis density profile. Simulation studies have suggested that shoulders are supported by looped x
1 orbits, occur in growing bars, and can appear after bar buckling. We investigate the orbital support and evolution of shoulders via frequency analyses of orbits in simulations. We confirm that looped orbits are shoulder-supporting, and can remain so, to a lesser extent, after being vertically thickened. We show that looped orbits appear at the resonance ( Ω
φ
− ΩP)/Ω
R
= 1/2 (analogous to the classical inner Lindblad resonance, and here called ILR) with vertical-to-radial frequency ratios 1 ≲ Ω
z
/Ω
R
≲ 3/2 (vertically warm orbits). Cool orbits at the ILR (those with Ω
z
/Ω
R
> 3/2) are vertically thin and have no loops, contributing negligibly to shoulders. As bars slow and thicken, either secularly or by buckling, they populate warm orbits at the ILR. Further thickening carries these orbits toward crossing the vertical ILR [vILR, ( Ω
φ
− ΩP)/Ω
z
= 1/2], where they convert in-plane motion to vertical motion, become chaotic, kinematically hotter, and less shoulder-supporting. Hence, persistent shoulders require bars to trap new stars, consistent with the need for a growing bar. Since buckling speeds up trapping on warm orbits at the ILR, it can be followed by shoulder formation, as seen in simulations. This sequence supports the recent observational finding that shoulders likely precede the emergence of BP-bulges. The python module for the frequency analysis, naif, is made available.
The RS Oph Outburst of 2021 Monitored in X-Rays with NICER
Authors: Orio Marina , Gendreau Keith , Giese Morgan , Luna Gerardo Juan M. , Magdolen Jozef , Strohmayer Tod E. , Zhang Andy E. , Altamirano Diego , Dobrotka Andrej , Enoto Teruaki , Ferrara Elizabeth C. , Ignace Richard , Heinz Sebastian , Markwardt Craig , Nichols Joy S. , Parker Michael L. , Pasham Dheeraj R. , Pei Songpeng , Pradhan Pragati , Remillard Ron , Steiner James F. , Tombesi Francesco 
Published: September 2023

Abstract
The 2021 outburst of the symbiotic recurrent nova RS Oph was monitored with the Neutron Star Interior Composition Explorer Mission (NICER) in the 0.2–12 keV range from day one after the optical maximum, until day 88, producing an unprecedented, detailed view of the outburst development. The X-ray flux preceding the supersoft X-ray phase peaked almost 5 days after optical maximum and originated only in shocked ejecta for 21–25 days. The emission was thermal; in the first 5 days, only a non-collisional-ionization equilibrium model fits the spectrum, and a transition to equilibrium occurred between days 6 and 12. The ratio of peak X-ray flux measured in the NICER range to that measured with Fermi in the 60 MeV–500 GeV range was about 0.1, and the ratio to the peak flux measured with H.E.S.S. in the 250 GeV–2.5 TeV range was about 100. The central supersoft X-ray source (SSS), namely the shell hydrogen burning white dwarf (WD), became visible in the fourth week, initially with short flares. A huge increase in flux occurred on day 41, but the SSS flux remained variable. A quasi-periodic oscillation every ≃35 s was always observed during the SSS phase, with variations in amplitude and a period drift that appeared to decrease in the end. The SSS has characteristics of a WD of mass >1 M
⊙. Thermonuclear burning switched off shortly after day 75, earlier than in the 2006 outburst. We discuss implications for the nova physics.
Using Giant Pulses to Measure the Impulse Response of the Interstellar Medium
Authors: Mahajan Nikhil , van Kerkwijk Marten H. 
Published: September 2023

Abstract
Giant pulses emitted by PSR B1937+21 are bright, intrinsically impulsive bursts. Thus, the observed signal from a giant pulse is a noisy but direct measurement of the impulse response from the ionized interstellar medium. We use this fact to detect 13,025 giant pulses directly in the baseband data of two observations of PSR B1937+21. Using the giant pulse signals, we model the time-varying impulse response with a sparse approximation method, in which the time dependence at each delay is decomposed in Fourier components, thus constructing a wavefield as a function of delay and differential Doppler shift. We find that the resulting wavefield has the expected parabolic shape with several diffuse structures within it, suggesting the presence of multiple scattering locations along the line of sight. We also detect an echo at a delay of about 2.4 ms, over 1.5 times the rotation period of the pulsar, which moves along the trajectory expected from geometry between the two observations. The structures in the wavefield are insufficiently sparse to produce a complete model of the system; hence, the model is not predictive across gaps larger than about the scintillation time. Nevertheless, within its range, it reproduces about 75% of the power of the impulse response, a fraction limited mostly by the signal-to-noise ratio of the observations. Furthermore, we show that by deconvolution, using the model impulse response, we can successfully recover the intrinsic pulsar emission from the observed signal.
A Gradual Decline of Star Formation since Cluster Infall: New Kinematic Insights into Environmental Quenching at 0.3 < z < 1.1
Authors: Kim Keunho J. , Bayliss Matthew B. , Noble Allison G. , Khullar Gourav , Cronk Ethan , Roberson Joshua , Ansarinejad Behzad , Bleem Lindsey E. , Floyd Benjamin , Grandis Sebastian , Mahler Guillaume , McDonald Michael A. , Reichardt Christian L. , Saro Alexandro , Sharon Keren , Somboonpanyakul Taweewat , Strazzullo Veronica 
Published: September 2023

Abstract
The environments where galaxies reside crucially shape their star formation histories. We investigate a large sample of 1626 cluster galaxies located within 105 galaxy clusters spanning a large range in redshift (0.26 < z < 1.13). The galaxy clusters are massive (M
500 ≳ 2 × 1014
M
⊙) and uniformly selected from the SPT and ACT Sunyaev–Zel’dovich surveys. With spectra in hand for thousands of cluster members, we use the galaxies’ position in projected phase space as a proxy for their infall times, which provides a more robust measurement of environment than quantities such as projected clustercentric radius. We find clear evidence for a gradual age increase of the galaxy’s mean stellar populations (∼0.71 ± 0.4 Gyr based on a 4000 Å break, Dn4000) with the time spent in the cluster environment. This environmental quenching effect is found regardless of galaxy luminosity (faint or bright) and redshift (low or high-z), although the exact stellar age of galaxies depends on both parameters at fixed environmental effects. Such a systematic increase of Dn4000 with infall proxy would suggest that galaxies that were accreted into hosts earlier were quenched earlier due to longer exposure to environmental effects such as ram pressure stripping and starvation. Compared to the typical dynamical timescales of 1–3 Gyr of cluster galaxies, the relatively small age increase (∼0.71 ± 0.4 Gyr) found in our sample galaxies seems to suggest that a slow environmental process such as starvation is the dominant quenching pathway. Our results provide new insights into environmental quenching effects spanning a large range in cosmic time (∼5.2 Gyr, z = 0.26–1.13) and demonstrate the power of using a kinematically derived infall time proxy.
Stellar Collisions in the Galactic Center: Massive Stars, Collision Remnants, and Missing Red Giants
Authors: Rose Sanaea C. , Naoz Smadar , Sari Re’em , Linial Itai 
Published: September 2023

Abstract
Like most galaxies, the Milky Way harbors a supermassive black hole (SMBH) at its center, surrounded by a nuclear star cluster. In this dense star cluster, direct collisions can occur between stars before they evolve off the main sequence. Using a statistical approach, we characterize the outcomes of these stellar collisions within the inner parsec of the Galactic center (GC). Close to the SMBH, where the velocity dispersion is larger than the escape speed from a Sun-like star, collisions lead to mass loss. We find that the stellar population within 0.01 pc is halved within about a billion years because of destructive collisions. Additionally, we predict a diffuse population of peculiar low-mass stars in the GC. These stars have been divested of their outer layers in the inner 0.01 pc before migrating to larger distances from the SMBH. Between 0.01 and 0.1 pc from the SMBH, collisions can result in mergers. Our results suggest that repeated collisions between lower-mass stars can produce massive (≳10 M
⊙) stars, and that there may be ∼100 of them residing in this region. We provide predictions on the number of so-called G objects, dust- and gas-enshrouded stellar objects, that may result from main-sequence stellar collisions. Lastly, we comment on uncertainties in our model and possible connections between stellar collisions and the missing red giants in the GC.
A Multiwavelength Investigation of Dust and Stellar Mass Distributions in Galaxies: Insights from High-resolution JWST Imaging
Authors: Liu Zhaoran , Morishita Takahiro , Kodama Tadayuki 
Published: September 2023

Abstract
We study the morphological properties of mid-infrared selected galaxies at 1.0 < z < 1.7 in the SMACS J0723.3-7327 cluster field to investigate the mechanisms of galaxy mass assembly and structural formation at cosmic noon. We develop a new algorithm to decompose the dust and stellar components of individual galaxies by using high-resolution images in the MIRI F770W and NIRCam F200W bands. Our analysis reveals that a significant number of galaxies with stellar masses between 109.5 < M
*/M
⊙ < 1010.5 exhibit dust cores that are relatively more compact than their stellar cores. Specifically, within this mass range, the nonparametric method indicates that the dust cores are 1.23 (±0.05) times more compact than the stellar cores on average when evaluated with flux concentration of the two components within a fixed radius. Similarly, the parametric method yields an average compactness ratio of 1.27 (±0.06). Notably, the most massive galaxy (M
* ∼ 1010.9
M
⊙) in our sample demonstrates a comparable level of compactness between its stellar core and dust, with a dust-to-stellar ratio of 0.86 (0.89) as derived from nonparametric (parametric) method. The observed compactness of the dust component is potentially attributed to the presence of a (rapidly growing) massive bulge that in some cases is associated with elevated star formation. Expanding the sample size through a joint analysis of multiple Cycle 1 deep-imaging programs can help to confirm the inferred picture. Our pilot study highlights that MIRI offers an efficient approach to studying the structural formation of galaxies from cosmic noon to the modern Universe.
Unique Chemical Composition of the Very Metal-poor Star LAMOST J1645+4357
Authors: Aoki Wako , Li Haining , Tominaga Nozomu , Matsuno Tadafumi , Honda Satoshi , Zhao Gang 
Published: September 2023

Abstract
We report on the chemical composition of the very metal-poor (VMP; [Fe/H] = −2.9) star LAMOST J1645+4357, which was identified as a red giant having peculiar abundance ratios by Li et al. The standard abundance analysis is carried out for this object and the well-studied metal-poor star HD 122563, which has similar atmospheric parameters. LAMOST J1645+4357 has a remarkable abundance set, highlighted by these features: (1) nitrogen is significantly enhanced ([N/Fe] = +1.4), and the total abundance of C and N is also very high ([(C+N)/Fe] = +0.9); (2) α-elements are overabundant with respect to iron, as generally found in VMP stars; (3) Ti, Sc, Co, and Zn are significantly deficient; (4) Cr and Mn are enhanced compared to most of VMP stars; and (5) Sr and Ba are deficient, and the Sr/Ba ratio ([Sr/Ba] = −1.0) is significantly lower than the value expected for the r-process. The overall abundance pattern of this object from C to Zn is well reproduced by a faint supernova model assuming spherical explosion, except for the excess of Cr and Mn, which requires enhancement of incomplete Si burning or small contributions from a Type Ia or pair-instability supernova. There remains, however, a question as to why the abundance pattern of this star is so unique among VMP stars.
A Self-gravity Module for the PLUTO Code
Authors: Mandal Ankush , Mukherjee Dipanjan , Mignone Andrea 
Published: September 2023

Abstract
We present a novel implementation of an iterative solver for the solution of Poisson’s equation in the PLUTO code for astrophysical fluid dynamics. Our solver relies on a relaxation method in which convergence is sought as the steady-state solution of a parabolic equation, whose time discretization is governed by the Runge–Kutta–Legendre (RKL) method. Our findings indicate that the RKL-based Poisson solver, which is both fully parallel and rapidly convergent, has the potential to serve as a practical alternative to conventional iterative solvers such as the Gauss–Seidel and successive overrelaxation methods. Additionally, it can mitigate some of the drawbacks of these traditional techniques. We incorporate our algorithm into a multigrid solver to provide a simple and efficient gravity solver that can be used to obtain the gravitational potentials in self-gravitational hydrodynamics. We test our implementation against a broad range of standard self-gravitating astrophysical problems designed to examine different aspects of the code. We demonstrate that the results match excellently with analytical predictions (when available), and the findings of similar previous studies.
Company for the Ultra-high Density, Ultra-short Period Sub-Earth GJ 367 b: Discovery of Two Additional Low-mass Planets at 11.5 and 34 Days*
Authors: Goffo Elisa , Gandolfi Davide , Egger Jo Ann , Mustill Alexander J. , Albrecht Simon H. , Hirano Teruyuki , Kochukhov Oleg , Astudillo-Defru Nicola , Barragan Oscar , Serrano Luisa M. , Hatzes Artie P. , Alibert Yann , Guenther Eike , Dai Fei , Lam Kristine W. F. , Csizmadia Szilárd , Smith Alexis M. S. , Fossati Luca , Luque Rafael , Rodler Florian , Winther Mark L. , Rørsted Jakob L. , Alarcon Javier , Bonfils Xavier , Cochran William D. , Deeg Hans J. , Jenkins Jon M. , Korth Judith , Livingston John H. , Meech Annabella , Murgas Felipe , Orell-Miquel Jaume , Osborne Hannah L. M. , Palle Enric , Persson Carina M. , Redfield Seth , Ricker George R. , Seager Sara , Vanderspek Roland , Van Eylen Vincent , Winn Joshua N. 
Published: September 2023

Abstract
GJ 367 is a bright (V ≈ 10.2) M1 V star that has been recently found to host a transiting ultra-short period sub-Earth on a 7.7 hr orbit. With the aim of improving the planetary mass and radius and unveiling the inner architecture of the system, we performed an intensive radial velocity follow-up campaign with the HARPS spectrograph—collecting 371 high-precision measurements over a baseline of nearly 3 yr—and combined our Doppler measurements with new TESS observations from sectors 35 and 36. We found that GJ 367 b has a mass of M
b = 0.633 ± 0.050 M
⊕ and a radius of R
b = 0.699 ± 0.024 R
⊕, corresponding to precisions of 8% and 3.4%, respectively. This implies a planetary bulk density of ρ
b = 10.2 ± 1.3 g cm−3, i.e., 85% higher than Earth’s density. We revealed the presence of two additional non-transiting low-mass companions with orbital periods of ∼11.5 and 34 days and minimum masses of

M

c

sin

i

c

= 4.13 ± 0.36 M
⊕ and

M

d

sin

i

d

= 6.03 ± 0.49 M
⊕, respectively, which lie close to the 3:1 mean motion commensurability. GJ 367 b joins the small class of high-density planets, namely the class of super-Mercuries, being the densest ultra-short period small planet known to date. Thanks to our precise mass and radius estimates, we explored the potential internal composition and structure of GJ 367 b, and found that it is expected to have an iron core with a mass fraction of

0.91

−
0.23

+
0.07

. How this iron core is formed and how such a high density is reached is still not clear, and we discuss the possible pathways of formation of such a small ultra-dense planet.
Coronal Heating Rate in the Slow Solar Wind
Authors: Telloni Daniele , Romoli Marco , Velli Marco , Zank Gary P. , Adhikari Laxman , Downs Cooper , Burtovoi Aleksandr , Susino Roberto , Spadaro Daniele , Zhao Lingling , Liberatore Alessandro , Shi Chen , De Leo Yara , Abbo Lucia , Frassati Federica , Jerse Giovanna , Landini Federico , Nicolini Gianalfredo , Pancrazzi Maurizio , Russano Giuliana , Sasso Clementina , Andretta Vincenzo , Da Deppo Vania , Fineschi Silvano , Grimani Catia , Heinzel Petr , Moses John D. , Naletto Giampiero , Stangalini Marco , Teriaca Luca , Uslenghi Michela , Berlicki Arkadiusz , Bruno Roberto , Capobianco Gerardo , Capuano Giuseppe E. , Casini Chiara , Casti Marta , Chioetto Paolo , Corso Alain J. , D’Amicis Raffaella , Fabi Michele , Frassetto Fabio , Giarrusso Marina , Giordano Silvio , Guglielmino Salvo L. , Magli Enrico , Massone Giuseppe , Messerotti Mauro , Nisticò Giuseppe , Pelizzo Maria G. , Reale Fabio , Romano Paolo , Schühle Udo , Solanki Sami K. , Straus Thomas , Ventura Rita , Volpicelli Cosimo A. , Zangrilli Luca , Zimbardo Gaetano , Zuppella Paola , Bale Stuart D. , Kasper Justin C. 
Published: September 2023

Abstract
This Letter reports the first observational estimate of the heating rate in the slowly expanding solar corona. The analysis exploits the simultaneous remote and local observations of the same coronal plasma volume, with the Solar Orbiter/Metis and the Parker Solar Probe instruments, respectively, and relies on the basic solar wind magnetohydrodynamic equations. As expected, energy losses are a minor fraction of the solar wind energy flux, since most of the energy dissipation that feeds the heating and acceleration of the coronal flow occurs much closer to the Sun than the heights probed in the present study, which range from 6.3 to 13.3 R
⊙. The energy deposited to the supersonic wind is then used to explain the observed slight residual wind acceleration and to maintain the plasma in a nonadiabatic state. As derived in the Wentzel–Kramers–Brillouin limit, the present energy transfer rate estimates provide a lower limit, which can be very useful in refining the turbulence-based modeling of coronal heating and subsequent solar wind acceleration.
Disentangling the Hadronic Components in NGC 1068
Authors: Ajello Marco , Murase Kohta , McDaniel Alex 
Published: September 2023

Abstract
The recent detection of high-energy neutrinos by IceCube in the direction of the nearby Seyfert/starburst galaxy NGC 1068 implies that radio-quiet active galactic nuclei can accelerate cosmic-ray ions. Dedicated multimessenger analyses suggest that the interaction of these high-energy ions with ambient gas or photons happens in a region of the galaxy that is highly opaque for GeV–TeV gamma rays. Otherwise, the GeV–TeV emission would violate existing constraints provided by the Fermi Large Area Telescope (LAT) and the Major Atmospheric Gamma Imaging Cherenkov. The conditions of high optical depth are realized near the central supermassive black hole (SMBH). At the same time, the GeV emission detected by the Fermi LAT is likely related to the galaxy’s sustained star formation activity. In this work, we derive a 20 MeV–1 TeV spectrum of NGC 1068 using 14 yr of Fermi LAT observations. We find that the starburst hadronic component is responsible for NGC 1068's emission above ∼500 MeV. However, below this energy, an additional component is required. In the 20–500 MeV range, the Fermi LAT data are consistent with hadronic emission initiated by non-thermal ions interacting with gas or photons in the vicinity of the central SMBH. This highlights the importance of the MeV band to discover hidden cosmic-ray accelerators.
Impact of a Nursing Intervention Bundle of Care on Nasal-CPAP-Related Nasal Injuries in Preterm Infants: A Quality Improvement Initiative
Authors: Mohamed Mohab , Noaman Ahmed , Nour Islam , Abdel-Hady Hesham 
Published: September 2023

AIM: The objective is to assess the effect of the application of a nasal injury prevention bundle on the incidence and severity of nasal-continuous positive airway pressure (nCPAP)-related nasal injuries in preterm infants.
METHODS: We conducted a prospective controlled before-after study in a preterm neonate, <37 weeks gestation, who required nCPAP in the neonatal intensive care unit, at Mansoura University Children’s Hospital, between September 2018 through October 2019. After 2 months of nursing staff training, a nasal trauma prevention bundle was implemented. The nursing intervention bundle comprised nasal barrier dressing, regular focused checking for evolving nasal skin injury, and proper application of the CPAP device. nCPAP-related nasal injuries per 1000 days and grading of nasal injury severity were the primary outcomes. Time to onset of nasal injury after initiation of CPAP; duration of nCPAP use, duration of oxygen dependency; incidence of pneumothorax, broncho-pulmonary dysplasia; intraventricular hemorrhage; periventricular leukomalacia; late-onset sepsis; length of hospital stay; and in-hospital mortality were the secondary outcomes.
RESULTS: Data from 62 preterm neonates were analyzed (31 in each group). The nasal trauma prevention bundle of care was associated with reduced nasal injury incidence per 1000 nCPAP-days (140 vs. 148.94, p = 0.03) with improved nasal injury severity staging (p = 0.003) compared to the pre-bundle era. Nasal injury developed earlier in the control group (1 [1–1] vs. 2 [1–3] days, p = 0.002) compared to the intervention group. No statistically significant differences were reported between groups regarding any of the other secondary outcomes. Longer duration of CPAP use (p = 0.009) and lack of bundle application (0.03) were the independent risk factors associated with nCPAP-related nasal injuries in preterm neonates.
CONCLUSION: The implementation of a bundle of nursing interventions is associated with a substantially improved incidence and severity of nasal injuries in preterm infants receiving nCPAP.