The Astrophysical Journal Letters最新文献_第9页

On the Origin of a Broad Quasiperiodic Fast-propagating Wave Train: Unwinding Jet as the Driver 关于宽准周期快速传播波列的起源：放卷射流是驱动力

The Astrophysical Journal Letters Pub Date : 2024-09-30 DOI: 10.3847/2041-8213/ad7a68

Xinping Zhou, Zehao Tang, Zhining Qu, Ke Yu, Chengrui Zhou, Yuqi Xiang, Ahmed Ahmed Ibrahim and Yuandeng Shen

{"title":"On the Origin of a Broad Quasiperiodic Fast-propagating Wave Train: Unwinding Jet as the Driver","authors":"Xinping Zhou, Zehao Tang, Zhining Qu, Ke Yu, Chengrui Zhou, Yuqi Xiang, Ahmed Ahmed Ibrahim and Yuandeng Shen","doi":"10.3847/2041-8213/ad7a68","DOIUrl":"https://doi.org/10.3847/2041-8213/ad7a68","url":null,"abstract":"Large-scale extreme-ultraviolet waves commonly exhibit as single wave front and are believed to be caused by coronal mass ejections. Utilizing high spatiotemporal resolution imaging observations from the Solar Dynamics Observatory, we present two sequentially generated wave trains originating from the same active region: a narrow quasiperiodic fast-propagating (QFP) wave train that propagates along the coronal loop system above the jet and a broad QFP wave train that travels along the solar surface beneath the jet. The measurements indicate that the narrow QFP wave train and the accompanying flare’s quasiperiodic pulsations (QPPs) have nearly identical onsets and periods. This result suggests that the accompanying flare process excites the observed narrow QFP wave train. However, the broad QFP wave train starts approximately 2 minutes before the QPPs of the flare, but it is consistent with the interaction between the unwinding jet and the solar surface. Moreover, we find that the period of the broad QFP wave train, approximately 130 s, closely matches that of the unwinding jet. This period is significantly longer than the 30 s period of the accompanying flare’s QPPs. Based on these findings, we propose that the intermittent energy release of the accompanying flare excited the narrow QFP wave train confined propagating in the coronal loop system. The unwinding jet, rather than the intermittent energy release in the accompanying flare, triggered the broad QFP wave train propagating along the solar surface.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142362732","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}

引用次数: 0

Massive Star Formation Starts in Subvirial Dense Clumps Unless Resisted by Strong Magnetic Fields 大质量恒星的形成始于亚气态致密星团，除非受到强磁场的阻挡

The Astrophysical Journal Letters Pub Date : 2024-09-30 DOI: 10.3847/2041-8213/ad7b08

Ke Wang, Yueluo Wang and Fengwei Xu

{"title":"Massive Star Formation Starts in Subvirial Dense Clumps Unless Resisted by Strong Magnetic Fields","authors":"Ke Wang, Yueluo Wang and Fengwei Xu","doi":"10.3847/2041-8213/ad7b08","DOIUrl":"https://doi.org/10.3847/2041-8213/ad7b08","url":null,"abstract":"Knowledge of the initial conditions of high-mass star formation is critical for theoretical models, but are not well observed. Built on our previous characterization of a Galaxy-wide sample of 463 candidate high-mass starless clumps (HMSCs), here we investigate the dynamical state of a representative subsample of 44 HMSCs (radii 0.13–1.12 pc) using Green Bank Telescope NH3 (1,1) and (2,2) data from the Radio Ammonia Mid-Plane Survey pilot data release. By fitting the two NH3 lines simultaneously, we obtain velocity dispersion, gas kinetic temperature, NH3 column density and abundance, Mach number, and virial parameter. Thermodynamic analysis reveals that most HMSCs have Mach number <5, inconsistent with what have been considered in theoretical models. All but one (43 out of 44) of the HMSCs are gravitationally bound with virial parameter αvir < 2. Either these massive clumps are collapsing or magnetic field strengths of 0.10–2.65 mG (average 0.51 mG) would be needed to prevent them from collapsing. The estimated B-field strength correlates tightly with density, , with a similar power-law index as found in observations but a factor of 4.6 higher in strength. For the first time, the initial dynamical state of high-mass formation regions has been statistically constrained to be subvirial, in contradiction to theoretical models in virial equilibrium and in agreement with the lack of observed massive starless cores. The findings urge future observations to quantify the magnetic field support in the prestellar stage of massive clumps, which has rarely been explored so far, toward a full understanding of the physical conditions that initiate massive star formation.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142362734","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}

引用次数: 0

Discovery of a Millisecond Pulsar Associated with Terzan 6 发现与泰尔赞 6 号有关的毫秒脉冲星

The Astrophysical Journal Letters Pub Date : 2024-09-30 DOI: 10.3847/2041-8213/ad7a69

Shi-Jie Gao, Yi-Xuan Shao, Pei Wang, Ping Zhou, Xiang-Dong Li, Lei Zhang, Joseph W. Kania, Duncan R. Lorimer and Di Li

{"title":"Discovery of a Millisecond Pulsar Associated with Terzan 6","authors":"Shi-Jie Gao, Yi-Xuan Shao, Pei Wang, Ping Zhou, Xiang-Dong Li, Lei Zhang, Joseph W. Kania, Duncan R. Lorimer and Di Li","doi":"10.3847/2041-8213/ad7a69","DOIUrl":"https://doi.org/10.3847/2041-8213/ad7a69","url":null,"abstract":"Observations show that globular clusters (GCs) might be among the best places to find millisecond pulsars (MSPs). However, the GC Terzan 6 seems to be an exception without any pulsar discovered, although its high stellar encounter rate suggests that it harbors dozens of them. We report the discovery of the first radio pulsar, PSR J1750–3116A, likely associated with Terzan 6 in a search of C-band (4–8 GHz) data from the Robert C. Byrd Green Bank Telescope with a spin period of 5.33 ms and dispersion measure (DM) ≃ 383 pc cm−3. The mean flux density of this pulsar is approximately 3 μJy. The DM agrees well with predictions from the Galactic free electron density model, assuming a distance of 6.7 kpc for Terzan 6. PSR J1750–3116A is likely an isolated MSP, potentially formed through dynamical interactions, considering the core-collapsed classification and the exceptionally high stellar encounter rate of Terzan 6. This is the highest radio frequency observation that has led to the discovery of a pulsar in a GC to date. While L-band (1–2 GHz) observations of this cluster are unlikely to yield significant returns due to propagation effects, we predict that further pulsar discoveries in Terzan 6 will be made by existing radio telescopes at higher frequencies.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142362735","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}

引用次数: 0

Lava Worlds Surface Measurements at High Temperatures 高温下的熔岩世界表面测量

The Astrophysical Journal Letters Pub Date : 2024-09-30 DOI: 10.3847/2041-8213/ad7d89

Marc-Antoine Fortin, Esteban Gazel, Daniel B. Williams, James O. Thompson, Lisa Kaltenegger and Michael S. Ramsey

{"title":"Lava Worlds Surface Measurements at High Temperatures","authors":"Marc-Antoine Fortin, Esteban Gazel, Daniel B. Williams, James O. Thompson, Lisa Kaltenegger and Michael S. Ramsey","doi":"10.3847/2041-8213/ad7d89","DOIUrl":"https://doi.org/10.3847/2041-8213/ad7d89","url":null,"abstract":"First measurements of the emission of lava worlds with the James Webb Space Telescope (JWST) probe the conditions on worlds so hot that their surfaces are likely molten or partially molten. These observations provide a unique opportunity to explore rocky planets’ evolution. Surfaces of lava world exoplanets can give insights into their composition and their interior workings. However, data of spectral emissivity of a wide range of potential exoplanet surface compositions and temperatures is required to understand JWST data. Here, we chose eight synthetic, potential exoplanet surfaces that span a wide range of chemical compositions to provide observers with a tool for the interpretation of JWST data for the exploration of lava worlds. We present the measured infrared emissivity spectra (2.5–20 μm) of these materials for temperatures between 800° C and 1350° C. Our data comprise the first spectral library of possible high-temperature exoplanet surfaces. From these measurements, we establish the link between composition and a strong spectral feature at around 9 μm, the Christiansen frequency (CF) for different temperatures. Additionally, we report that the shift in the CF associated with the bulk composition of the material is significantly more important than its temperature. This provides a critical tool to aid in interpreting future spectra of lava worlds that will be collected by the JWST and future missions.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142362736","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}

引用次数: 0

Nightside Clouds on Tidally Locked Terrestrial Planets Mimic Atmosphere-free Scenarios 潮汐锁定陆地行星上的夜侧云模拟无大气层情景

The Astrophysical Journal Letters Pub Date : 2024-09-30 DOI: 10.3847/2041-8213/ad78de

Diana Powell, Robin Wordsworth and Karin Öberg

引用次数: 0

Magnetic Field Geometry of the Gamma-Ray Binary PSR B1259–63 Revealed via X-Ray Polarization 通过 X 射线偏振揭示伽马射线双星 PSR B1259-63 的磁场几何特征

The Astrophysical Journal Letters Pub Date : 2024-09-30 DOI: 10.3847/2041-8213/ad7ba6

Philip Kaaret, Oliver J. Roberts, Steven R. Ehlert, Douglas A. Swartz, Martin C. Weisskopf, Ioannis Liodakis, M. Lynne Saade, Stephen L. O’Dell and Chien-Ting Chen

引用次数: 0

Element Formation in Radiation-hydrodynamics Simulations of Kilonovae 基洛新星辐射流体力学模拟中的元素形成

The Astrophysical Journal Letters Pub Date : 2024-09-30 DOI: 10.3847/2041-8213/ad74e0

Fabio Magistrelli, Sebastiano Bernuzzi, Albino Perego and David Radice

{"title":"Element Formation in Radiation-hydrodynamics Simulations of Kilonovae","authors":"Fabio Magistrelli, Sebastiano Bernuzzi, Albino Perego and David Radice","doi":"10.3847/2041-8213/ad74e0","DOIUrl":"https://doi.org/10.3847/2041-8213/ad74e0","url":null,"abstract":"Understanding the details of r-process nucleosynthesis in binary neutron star merger (BNSM) ejecta is key to interpreting kilonova observations and identifying the role of BNSMs in the origin of heavy elements. We present a self-consistent, two-dimensional, ray-by-ray radiation-hydrodynamic evolution of BNSM ejecta with an online nuclear network (NN) up to a timescale of days. For the first time, an initial numerical relativity ejecta profile composed of the dynamical component and spiral-wave and disk winds is evolved including detailed r-process reactions and nuclear heating effects. A simple model for the jet energy deposition is also included. Our simulation highlights that the common approach of relating in postprocessing the final nucleosynthesis yields to the initial thermodynamic profile of the ejecta can lead to inaccurate predictions. Moreover, we find that neglecting the details of the radiation-hydrodynamic evolution of the ejecta in nuclear calculations can introduce deviations of up to 1 order of magnitude in the final abundances of several elements, including very light and second r-process peak elements. The presence of a jet affects element production only in the innermost part of the polar ejecta, and it does not alter the global nucleosynthesis results. Overall, our analysis shows that employing an online NN improves the reliability of nucleosynthesis and kilonova light-curve predictions.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369297","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}

引用次数: 0

A Pileup of Coronal Mass Ejections Produced the Largest Geomagnetic Storm in Two Decades 日冕物质抛射堆积引发二十年来最大的地磁风暴

The Astrophysical Journal Letters Pub Date : 2024-09-30 DOI: 10.3847/2041-8213/ad7ba4

Ying D. Liu, Huidong Hu, Xiaowei Zhao, Chong Chen and Rui Wang

{"title":"A Pileup of Coronal Mass Ejections Produced the Largest Geomagnetic Storm in Two Decades","authors":"Ying D. Liu, Huidong Hu, Xiaowei Zhao, Chong Chen and Rui Wang","doi":"10.3847/2041-8213/ad7ba4","DOIUrl":"https://doi.org/10.3847/2041-8213/ad7ba4","url":null,"abstract":"The largest geomagnetic storm in two decades occurred in 2024 May with a minimum Dst of −412 nT. We examine its solar and interplanetary origins by combining multipoint imaging and in situ observations. The source active region, NOAA AR 13664, exhibited extraordinary activity and produced successive halo eruptions, which were responsible for two complex ejecta observed at the Earth. In situ measurements from STEREO A, which was 12.°6 apart, allow us to compare the “geo-effectiveness” at the Earth and STEREO A. We obtain key findings concerning the formation of solar superstorms and how mesoscale variations of coronal mass ejections affect geo-effectiveness: (1) the 2024 May storm supports the hypothesis that solar superstorms are “perfect storms” in nature, i.e., a combination of circumstances resulting in an event of an unusual magnitude; (2) the first complex ejecta, which caused the geomagnetic superstorm, shows considerable differences in the magnetic field and associated “geo-effectiveness” between the Earth and STEREO A, despite a mesoscale separation; and (3) two contrasting cases of complex ejecta are found in terms of the geo-effectiveness at the Earth, which is largely due to different magnetic field configurations within the same active region.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142362733","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}

引用次数: 0

Redshifted Sodium Transient near Exoplanet Transit 系外行星凌日附近的红移钠瞬态

The Astrophysical Journal Letters Pub Date : 2024-09-29 DOI: 10.3847/2041-8213/ad6b29

Apurva V. Oza, Julia V. Seidel, H. Jens Hoeijmakers, Athira Unni, Aurora Y. Kesseli, Carl A. Schmidt, Thirupathi Sivarani, Aaron Bello-Arufe, Andrea Gebek, Moritz Meyer zu Westram, Sérgio G. Sousa, Rosaly M. C. Lopes, Renyu Hu, Katherine de Kleer, Chloe Fisher, Sébastien Charnoz, Ashley D. Baker, Samuel P. Halverson, Nick M. Schneider, Angelica Psaridi, Aurélien Wyttenbach, Santiago Torres, Ishita Bhatnagar and Robert E. Johnson

{"title":"Redshifted Sodium Transient near Exoplanet Transit","authors":"Apurva V. Oza, Julia V. Seidel, H. Jens Hoeijmakers, Athira Unni, Aurora Y. Kesseli, Carl A. Schmidt, Thirupathi Sivarani, Aaron Bello-Arufe, Andrea Gebek, Moritz Meyer zu Westram, Sérgio G. Sousa, Rosaly M. C. Lopes, Renyu Hu, Katherine de Kleer, Chloe Fisher, Sébastien Charnoz, Ashley D. Baker, Samuel P. Halverson, Nick M. Schneider, Angelica Psaridi, Aurélien Wyttenbach, Santiago Torres, Ishita Bhatnagar and Robert E. Johnson","doi":"10.3847/2041-8213/ad6b29","DOIUrl":"https://doi.org/10.3847/2041-8213/ad6b29","url":null,"abstract":"Neutral sodium (Na i) is an alkali metal with a favorable absorption cross section such that tenuous gases are easily illuminated at select transiting exoplanet systems. We examine both the time-averaged and time-series alkali spectral flux individually, over 4 nights at a hot Saturn system on a ∼2.8 day orbit about a Sun-like star WASP-49 A. Very Large Telescope/ESPRESSO observations are analyzed, providing new constraints. We recover the previously confirmed residual sodium flux uniquely when averaged, whereas night-to-night Na i varies by more than an order of magnitude. On HARPS/3.6 m Epoch II, we report a Doppler redshift at vΓ,NaD = + 9.7 ± 1.6 km s−1 with respect to the planet’s rest frame. Upon examining the lightcurves, we confirm night-to-night variability, on the order of ∼1%–4% in NaD, rarely coinciding with exoplanet transit, not readily explained by stellar activity, starspots, tellurics, or the interstellar medium. Coincident with the ∼+10 km s−1 Doppler redshift, we detect a transient sodium absorption event dFNaD/F⋆ = 3.6% ± 1% at a relative difference of ΔFNaD(t) ∼ 4.4% ± 1%, lasting ΔtNaD ≳ 40 minutes. Since exoplanetary alkali signatures are blueshifted due to the natural vector of radiation pressure, estimated here at roughly ∼−5.7 km s−1, the radial velocity is rather at +15.4 km s−1, far larger than any known exoplanet system. Given that the redshift magnitude vΓ is in between the Roche limit and dynamically stable satellite orbits, the transient sodium may be a putative indication of a natural satellite orbiting WASP-49 A b.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142360096","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}

引用次数: 0

Ba Enrichment in Gaia MS+WD Binaries: Tracing s-process Element Production Gaia MS+WD 双星中的 Ba 富集：追踪 s 过程元素生成

The Astrophysical Journal Letters Pub Date : 2024-09-26 DOI: 10.3847/2041-8213/ad77b9

Param Rekhi, Sagi Ben-Ami, Na’ama Hallakoun, Sahar Shahaf, Silvia Toonen and Hans-Walter Rix

{"title":"Ba Enrichment in Gaia MS+WD Binaries: Tracing s-process Element Production","authors":"Param Rekhi, Sagi Ben-Ami, Na’ama Hallakoun, Sahar Shahaf, Silvia Toonen and Hans-Walter Rix","doi":"10.3847/2041-8213/ad77b9","DOIUrl":"https://doi.org/10.3847/2041-8213/ad77b9","url":null,"abstract":"A large population of intermediate-separation binaries, consisting of a main-sequence (MS) star and a white dwarf (WD), recently emerged from Gaia’s third data release (DR3), posing challenges to current models of binary evolution. Here we examine the s-process element abundances in these systems using data from GALAH DR3. Following refined sample analysis with parameter estimates based on GALAH spectra, we find a distinct domain where enhanced s-process elemental abundances depend on both the WD mass and metallicity, consistent with parameter spaces identified in previous asymptotic giant branch (AGB) nucleosynthesis studies having higher s-process yields. Notably, these enhanced abundances show no correlation with the systems’ orbital parameters, supporting a history of accretion in intermediate-separation MS+WD systems. Consequently, our results form direct observational evidence of a connection between AGB masses and s-process yields. We conclude by showing that the GALAH DR3 survey includes numerous Ba dwarf stars, within and beyond the mass range covered in our current sample, which can further elucidate s-process element distributions in MS+WD binaries.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142329208","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}

引用次数: 0