The Astrophysical Journal最新文献

{"title":"Evidence for Jet/Outflow Shocks Heating the Environment around the Class I Protostellar Source Elias 29: FAUST XXI","authors":"Yoko Oya, Eri Saiga, Anna Miotello, Maria Koutoulaki, Doug Johnstone, Cecilia Ceccarelli, Claire J. Chandler, Claudio Codella, Nami Sakai, Eleonora Bianchi, Mathilde Bouvier, Steven Charnley, Nicolas Cuello, Marta De Simone, Logan Francis, Tomoyuki Hanawa, Izaskun Jiménez-Serra, Laurent Loinard, Francois Menard, Giovanni Sabatini, Charlotte Vastel, Ziwei Zhang, Yuri Aikawa, Felipe O. Alves, Nadia Balucani, Gemma Busquet, Paola Caselli, Emmanuel Caux, Spandan Choudhury, Francois Dulieu, Aurora Durán, Lucy Evans, Davide Fedele, Siyi Feng, Francesco Fontani, Tetsuya Hama, Eric Herbst, Shingo Hirano, Tomoya Hirota, Andrea Isella, Claudine Kahane, Bertrand Lefloch, Romane Le Gal, Hauyu Baobab Liu, Ana López-Sepulcre, Luke T. Maud, María José Maureira, Seyma Mercimek, George Moellenbrock, Shoji Mori, Hideko Nomura, Yasuhiro Oba, Ross O’Donoghue, Satoshi Ohashi, Yuki Okoda, Juan Ospina-Zamudio, Jaime Pineda, Linda Podio, Albert Rimola, Takeshi Sakai, Dominique Segura-Cox, Yancy Shir..","doi":"10.3847/1538-4357/adabe7","DOIUrl":"https://doi.org/10.3847/1538-4357/adabe7","url":null,"abstract":"We have observed the late Class I protostellar source Elias 29 at a spatial resolution of 70 au with the Atacama Large Millimeter/submillimeter Array as part of the FAUST Large Program. We focus on the line emission of SO, while that of 34SO, C18O, CS, SiO, H13CO+, and DCO+ are used supplementarily. The spatial distribution of the SO rotational temperature (Trot(SO)) is evaluated by using the intensity ratio of its two rotational excitation lines. Besides in the vicinity of the protostar, two hot spots are found at a distance of 500 au from the protostar; Trot(SO) locally rises to 53 K at the interaction point of the outflow and the southern ridge, and 72 K within the southeastern outflow probably due to a jet-driven bow shock. However, the SiO emission is not detected at these hot spots. It is likely that active gas accretion through the disk-like structure and onto the protostar still continues even at this evolved protostellar stage, at least sporadically, considering the outflow/jet activities and the possible infall motion previously reported. Interestingly, Trot(SO) is as high as 20–30 K even within the quiescent part of the southern ridge apart from the protostar by 500–1000 au without clear kinematic indication of current outflow/jet interactions. Such a warm condition is also supported by the low deuterium fractionation ratio of HCO+ estimated by using the H13CO+ and DCO+ lines. The B-type star HD147889 ∼0.5 pc away from Elias 29, previously suggested as a heating source for this region, is likely responsible for the warm condition of Elias 29.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143451652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extracting the X-Ray Reverberation Response Functions from the Active Galactic Nucleus Light Curves Using an Autoencoder","authors":"Sanhanat Deesamutara, Poemwai Chainakun, Tirawut Worrakitpoonpon, Kamonwan Khanthasombat, Wasutep Luangtip, Jiachen Jiang, Francisco Pozo Nuñez and Andrew J. Young","doi":"10.3847/1538-4357/adae85","DOIUrl":"https://doi.org/10.3847/1538-4357/adae85","url":null,"abstract":"We study the X-ray reverberation in active galactic nuclei (AGN) using the variational autoencoder (VAE), which is a machine learning algorithm widely used for signal processing and feature reconstruction. While the X-ray reverberation signatures that contain the information of the accretion disk and the X-ray-emitting corona are commonly analyzed in the Fourier domain, this work aims to extract the reverberation response functions directly from the AGN light curves. The VAE is trained using the simulated light curves that contain the primary X-rays from the lamppost corona, varying its height and the corresponding reflection X-rays from the disk. We use progressively more realistic light-curve models, such as those that include the effects of disk-propagating fluctuations and random noises, to assess the ability of the VAE to reconstruct the response profiles. Interestingly, the VAE can recognize the reverberation patterns on the light curves; hence, the coronal height can be predicted. We then deploy the VAE model on the XMM-Newton data of IRAS 13224–3809 and directly estimate, for the first time, the response functions of this source in various observations. The result reveals the corona changing its height between 3rg and 20rg, which is correlated with the source luminosity and in line with previous literature. Finally, we discuss the advantages and limitations of this method.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"64 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143451831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Nonstop Aurora? The Intriguing Radio Emission from the Rapidly Rotating Magnetic Massive Star HR 5907","authors":"Ayan Biswas, Barnali Das, James A. Barron, Gregg A. Wade and Gonzalo Holgado","doi":"10.3847/1538-4357/adae02","DOIUrl":"https://doi.org/10.3847/1538-4357/adae02","url":null,"abstract":"HR 5907 (HD 142184) stands out among magnetic OB stars for its rapid rotation, exceptionally hard X-ray emission, and strong magnetic field. High-frequency (>5 GHz) radio emission from the star exhibits an approximately flat spectrum that can be attributed to gyrosynchrotron emission from a dense centrifugal magnetosphere. In a survey of radio emission from massive stars at sub-GHz frequencies, we noticed remarkable low-frequency radio emission from this star, characterized by high circular polarization and brightness temperature, which is inconsistent with the gyrosynchrotron model. We present a follow-up low-frequency radio study of this star with the upgraded Giant Metrewave Radio Telescope in search of emission mechanisms that can go undiagnosed at higher frequencies. We detect variable radio emission characterized by varying degrees of circular polarization (15%–45%) throughout the rotation cycle. The broadband spectral fitting also suggests additional emission components at lower frequencies. We show that the observed emission is likely auroral emission via electron cyclotron maser emission (ECME) and identify this star as a main-sequence radio pulse emitter (MRP). For MRPs, ECME is usually observed as short polarized enhancements near the magnetic nulls of the star. The detection of a high degree of circular polarization (>15%) at all times makes HR 5907 unique among MRPs. This is only the second MRP after ρ Oph C (detected polarization fraction: 0%–60%) that exhibits persistent coherent radio emission attributed to the nearly aligned stellar magnetic and rotational axes.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"85 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143451658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Studying the Radiation of a White Dwarf Star Falling onto a Black Hole","authors":"Marek Nikołajuk, Tomasz Karpiuk, Lorenzo Ducci and Mirosław Brewczyk","doi":"10.3847/1538-4357/adae8c","DOIUrl":"https://doi.org/10.3847/1538-4357/adae8c","url":null,"abstract":"We investigate electromagnetic and gravitational radiation generated during the process of the tidal stripping of a white dwarf star circulating a black hole. We go beyond Chandrasekhar’s ideas and not only consider the white dwarf itself as a quantum object, but also describe the dynamics of the produced accretion disk in a quantum way. We model the white dwarf star as a Bose–Fermi droplet and use the quantum hydrodynamic equations to simulate the evolution of the black hole–white dwarf binary system. While going through periastron, the white dwarf loses a small fraction of its mass. The mass falling onto a black hole is a source of powerful electromagnetic and gravitational radiation. Bursts of ultraluminous radiation are flared at each periastron passage. This resembles the recurrent flaring of X-ray sources discovered recently by Irwin et al. Gravitational energy bursts occur mainly through emission at very low frequencies. The accretion disk, formed due to stripping of the white dwarf, starts at some point to contribute continuously to radiation of both electromagnetic and gravitational types.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143451659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High Lithium Abundance Connection with the Chromospheric Helium in Red Giants: Spectroscopic and Asteroseismic Analyses","authors":"Anohita Mallick, Christopher Sneden, Bacham E. Reddy and Melike Afşar","doi":"10.3847/1538-4357/adab78","DOIUrl":"https://doi.org/10.3847/1538-4357/adab78","url":null,"abstract":"We present a study of correlations between high Li abundances and strong chromospheric He iλ10830 absorption-line strengths in Kepler field giant stars. Our sample includes 84 giants with detectable solar-like oscillations in their light curves, and their Li abundances come from the literature or are measured here using LAMOST medium-resolution spectra. Evolutionary phases are determined through asteroseismic analysis, with mixed-mode period spacing (ΔP) used to infer the time evolution of red clump (RC) giants. Near-IR observations of the He iλ10830 line were obtained with the high-resolution Habitable-zone Planet Finder spectrograph on the Hobby–Eberly Telescope. We find high Li abundances and strong He i lines exclusively among RC giants, with their absence in red giant branch stars suggesting a shared origin linked to the He flash. Additionally, a steady decline in He i strength with decreasing Li abundance among RC giants indicates a correlation between these properties. Older, Li-normal RC giants are He weak, while most younger, super-Li-rich giants are He strong, suggesting temporal evolution of both phenomena. We hypothesize that the core He flash and subsequent subflashes may enhance Li abundances in RC giant photospheres and trigger heightened chromospheric activity, leading to stronger He iλ10830 lines in younger RCs. Over time, following He flash, chromospheric activity diminishes, resulting in weaker He i lines in older, Li-normal RCs.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143451653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Asymmetric Temperature Variations In Protoplanetary Disks. I. Linear Theory, Corotating Spirals, and Ring Formation","authors":"Zhaohuan Zhu, 照寰 朱, Shangjia Zhang, 尚嘉 张 and Ted M. Johnson","doi":"10.3847/1538-4357/adae0d","DOIUrl":"https://doi.org/10.3847/1538-4357/adae0d","url":null,"abstract":"Protoplanetary disks can exhibit asymmetric temperature variations due to phenomena such as shadows cast by the inner disk or localized heating by young planets. We investigate the disk features induced by these asymmetric temperature variations. We find that spirals are initially excited, and then break into two and reconnect to form rings. By carrying out linear analyses, we first study the spiral launching mechanism and find that the effects of azimuthal temperature variations share similarities with effects of external potentials. Specifically, rotating temperature variations launch steady spiral structures at Lindblad resonances, which corotate with the temperature patterns. When the cooling time exceeds the orbital period, these spiral structures are significantly weakened, and a checkerboard pattern may appear. A temperature variation of about 10% can induce spirals with order unity density perturbations, comparable to those generated by a thermal mass planet. We then study ring formation and find it is related to the coupling between azimuthal temperature variations and spirals outside the resonances. Such coupling leads to a radially varying angular momentum flux, which produces anomalous wave-driven accretion and forms dense rings separated by the wavelength of the waves. Finally, we speculate that spirals induced by temperature variations may contribute to disk accretion through nonlinear wave steepening and dissipation. Overall, considering that irradiation determines the temperature structure of protoplanetary disks, the change of irradiation both spatially or/and temporarily may produce observable effects in protoplanetary disks, especially spirals and rings in outer disks beyond tens of au.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143451655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fast and Efficient Bayesian Method to Search for Strongly Lensed Gravitational Waves","authors":"Ankur Barsode, Srashti Goyal and Parameswaran Ajith","doi":"10.3847/1538-4357/adae10","DOIUrl":"https://doi.org/10.3847/1538-4357/adae10","url":null,"abstract":"A small fraction of the gravitational-wave (GW) signals from binary black holes observable by ground-based detectors will be strongly lensed by intervening objects such as galaxies and clusters. Strong lensing will produce nearly identical copies of the GW signals separated in time. These lensed signals must be identified against a background of unlensed pairs GW events, some of which may appear similar by accident. This is usually done using fast, but approximate methods that, for example, check for the overlap between the posterior distributions of a subset of binary parameters, or using slow, but accurate joint Bayesian parameter estimation. In this work, we present a modified version of the posterior overlap method dubbed “PO2.0” that is mathematically equivalent to joint parameter estimation while still remaining fast. We achieve a significant gain in efficiency by incorporating informative priors about the binary and lensing populations, selection effects, and all the inferred parameters of the binary. For binary black hole signals lensed by galaxies, our improved method can detect 65% lensed events at a pairwise false alarm probability of ∼2 × 10−6. Consequently, we have a 13% probability of detecting a strongly lensed event above 2.25σ significance during 18 months of observation by the LIGO-Virgo detectors at their current sensitivity. We also show how we can compute the joint posteriors of the lens and source parameters from a pair of lensed events by reweighting the posteriors of individual events in a computationally inexpensive way.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143451656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ALMA 0.1 pc View of Molecular Clouds Associated with High-mass Protostellar Systems in the Small Magellanic Cloud: Are Low-metallicity Clouds Filamentary or Not?","authors":"Kazuki Tokuda, Yuri Kunitoshi, Sarolta Zahorecz, Kei E. I. Tanaka, Itsuki Murakoso, Naoto Harada, Masato I. N. Kobayashi, Tsuyoshi Inoue, Marta Sewiło, Ayu Konishi, Takashi Shimonishi, Yichen Zhang, Yasuo Fukui, Akiko Kawamura, Toshikazu Onishi and Masahiro N. Machida","doi":"10.3847/1538-4357/ada5f8","DOIUrl":"https://doi.org/10.3847/1538-4357/ada5f8","url":null,"abstract":"Filamentary molecular clouds are an essential intermediate stage in the star formation process. To test whether these structures are universal throughout cosmic star formation history, it is crucial to study low-metallicity environments within the Local Group. We present an analysis of Atacama Large Millimeter/submillimeter Array (ALMA) archival data at the spatial resolution of ~0.1 pc for 17 massive young stellar objects (YSOs) in the Small Magellanic Cloud (SMC; Z ~ 0.2 Z⊙). This sample represents approximately 30% of the YSOs confirmed by Spitzer spectroscopy. Early ALMA studies of the SMC have shown that the CO emission line traces an H2 number density of ≳104 cm−3, an order of magnitude higher than in typical Galactic environments. Using the CO(J = 3–2) data, we investigate the spatial and velocity distribution of molecular clouds. Our analysis shows that about 60% of the clouds have steep radial profiles from the spine of the elongated structures, while the remaining clouds have a smooth distribution and are characterized by lower brightness temperatures. We categorize the former as filaments and the latter as nonfilaments. Some of the filamentary clouds are associated with YSOs with outflows and exhibit higher temperatures, likely reflecting their formation conditions, suggesting that these clouds are younger than the nonfilamentary ones. This indicates that even if filaments form during star formation, their steep structures may become less prominent and transition to a lower-temperature state. Such transitions in structure and temperature have not been reported in metal-rich regions, highlighting a key behavior for characterizing the evolution of the interstellar medium and star formation in low-metallicity environments.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143452140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Bias-free Deep Learning Approach for Automated Sunspot Segmentation","authors":"Jing Chen, Norbert G. Gyenge, Ye Jiang, Robertus Erdélyi, Jiajia Liu and Yimin Wang","doi":"10.3847/1538-4357/adac5e","DOIUrl":"https://doi.org/10.3847/1538-4357/adac5e","url":null,"abstract":"Solar activities significantly influence space weather and the Earth’s environment, necessitating accurate and efficient sunspot detection. This study explores deep learning methods to automate sunspot identification in solar satellite images, keeping personal bias to a minimum. Utilizing observations of the Solar Dynamics Observatory, we leverage active-region data from the Helioseismic Magnetic Imager active-region patches to locate sunspot groups detected between 2011 and 2023. The Morphological Active Contour Without Edges technique is applied to produce pseudo-labels, which are utilized to train the U-Net deep learning architecture, combining their strengths for robust segmentation. Evaluation metrics—including precision, recall, F1-score, intersection over union, and Dice coefficient—demonstrate the superior performance of U-Net. Our approach achieves a high Pearson correlation coefficient of 0.97 when compared with the sunspot area estimation of the Space Weather Prediction Center and 0.96 in comparison with the Debrecen Photoheliographic Data. This hybrid methodology provides a powerful tool for sunspot identification, offering the improved accuracy and efficiency crucial for space-weather prediction.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143451654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fractality of Magnetic Helicity Distribution in the Solar Corona","authors":"Anda Xiong, Shangbin Yang, Quan Wang and Xin Liu","doi":"10.3847/1538-4357/adaaed","DOIUrl":"https://doi.org/10.3847/1538-4357/adaaed","url":null,"abstract":"We find a universal power-law scaling of magnetic helicity distribution in the solar corona. Magnetic helicity is a dynamical invariant for ideal magnetohydrodynamics (MHD) and characterizes complex magnetic field structure by measuring the degree of knottiness of its field lines. We treat turbulent solar magnetic field as a superposition of random waves and develop a statistical topology method regarding the randomly tangled field lines. Based on the statistical behavior of the field lines, we consider their topology-specified structure and theoretically derive power laws for the distribution of magnetic flux and helicity. We find a power law of −7/4 to the magnetic helicity distribution when the field line topology is equivalent to handle and −5/4 when the field line topology is local open curve. We verify the universality of this new magnetic helicity fractality by observation to a number of 185 sunspots in newly emerging active regions during the 23rd and 24th solar cycle. This new distribution law reveals the fractal structure of the solar magnetic field.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"76 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143451704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}