The Astrophysical Journal Letters最新文献_第3页

Protoplanetary Disk Size under Nonideal Magnetohydrodynamics: A General Formalism with Inclined Magnetic Field 非理想磁流体力学下的原行星盘尺寸：带倾斜磁场的通用公式化

The Astrophysical Journal Letters Pub Date : 2024-01-05 DOI: 10.3847/2041-8213/ad192a

Yueh-Ning 悅寧 Lee 李, Barshan Ray, Pierre Marchand, P. Hennebelle

引用次数: 0

New Horizons Venetia Burney Student Dust Counter Observes Higher than Expected Fluxes Approaching 60 au 新视野号 "Venetia Burney 学生尘埃计数器观测到高于预期的通量，接近 60 au

The Astrophysical Journal Letters Pub Date : 2024-01-02 DOI: 10.3847/2041-8213/ad18b0

A. Doner, M. Horányi, Fran Bagenal, Pontus Brandt, Will Grundy, Carey Lisse, Joel Parker, A. Poppe, Kelsi N. Singer, S. A. Stern, A. Verbiscer

{"title":"New Horizons Venetia Burney Student Dust Counter Observes Higher than Expected Fluxes Approaching 60 au","authors":"A. Doner, M. Horányi, Fran Bagenal, Pontus Brandt, Will Grundy, Carey Lisse, Joel Parker, A. Poppe, Kelsi N. Singer, S. A. Stern, A. Verbiscer","doi":"10.3847/2041-8213/ad18b0","DOIUrl":"https://doi.org/10.3847/2041-8213/ad18b0","url":null,"abstract":"\u0000 The NASA New Horizons Venetia Burney Student Dust Counter (SDC) measures dust particle impacts along the spacecraft’s flight path for grains with mass ≥10−12 g, mapping out their spatial density distribution. We present the latest SDC dust density, size distribution, and flux measurements through 55 au and compare them to numerical model predictions. Kuiper Belt objects (KBOs) are thought to be the dominant source of interplanetary dust particles in the outer solar system due to both collisions between KBOs and their continual bombardment by interstellar dust particles. Continued measurements through 55 au show higher than model-predicted dust fluxes as New Horizons approaches the putative outer edge of the Kuiper Belt (KB). We discuss potential explanations for the growing deviation: radiation pressure stretches the dust distribution to further heliocentric distances than its parent body distribution; icy dust grains undergo photosputtering that rapidly increases their response to radiation pressure forces and pushes them further away from the Sun; and the distribution of KBOs may extend much further than existing observations suggest. Ongoing SDC measurements at even larger heliocentric distances will continue to constrain the contributions of dust production in the KB. Continued SDC measurements remain crucial for understanding the Kuiper Belt and the interpretation of dust disks around other stars.","PeriodicalId":507476,"journal":{"name":"The Astrophysical Journal Letters","volume":"8 23","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139631008","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

Transverse MHD Waves as Signatures of Braiding-induced Magnetic Reconnection in Coronal Loops 作为日冕环中编织诱导磁性再连接特征的横向 MHD 波

The Astrophysical Journal Letters Pub Date : 2024-01-01 DOI: 10.3847/2041-8213/ad1402

A. R. C. Sukarmadji, Patrick Antolin

{"title":"Transverse MHD Waves as Signatures of Braiding-induced Magnetic Reconnection in Coronal Loops","authors":"A. R. C. Sukarmadji, Patrick Antolin","doi":"10.3847/2041-8213/ad1402","DOIUrl":"https://doi.org/10.3847/2041-8213/ad1402","url":null,"abstract":"\u0000 A major coronal heating theory based on magnetic reconnection relies on the existence of braided magnetic field structures in the corona. In this small-angle reconnection scenario, numerical simulations indicate that the reconnected magnetic field lines are driven sideways by magnetic tension and can overshoot from their new rest position, thereby leading to low-amplitude transverse MHD waves. This provides an efficient mechanism for transverse MHD wave generation, and the direct causality also constitutes substantial evidence of reconnection from braiding. However, this wave-generation mechanism has never been directly observed. Recently, the telltale signature of small-angle reconnection in a sheared coronal structure has been identified through nanojets, which are small, short-lived, and fast jetlike bursts in the nanoflare range transverse to the guide field. We present for the first time Interface Region Imaging Spectrograph and Solar Dynamics Observatory observations of transverse MHD waves in a coronal loop that directly result from braiding-induced reconnection. The reconnection is identified by the presence of nanojets at the loop apex that release nanoflare-range energy. We find that the oscillations have an energy flux on the order of 106–108 erg cm−2 s−1, which is within the budget to power active region loops. The estimated kinetic and thermal energy from the nanojets is also sufficient to power the transverse waves and sustain the observed heating at the loop apex. This discovery provides major support to (a) existing theories that transverse MHD waves can be a signature of reconnection, (b) the existence of braiding in coronal structures, and (c) the coronal reconnection scenario identified by nanojets.","PeriodicalId":507476,"journal":{"name":"The Astrophysical Journal Letters","volume":"239 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139636226","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

Erratum: “Highest Redshift Image of Neutral Hydrogen in Emission: A CHILES Detection of a Starbursting Galaxy at z = 0.376” (2016, ApJL, 824, L1) 勘误：《发射中性氢的最高红移图像：z=0.376的星爆星系的CHILES探测"（2016，ApJL，824，L1）

The Astrophysical Journal Letters Pub Date : 2023-12-01 DOI: 10.3847/2041-8213/ad151e

X. Fernández, H. Gim, J. V. van Gorkom, M. Yun, Emmanuel Momjian, A. Popping, L. Chomiuk, K. Hess, L. Hunt, K. Kreckel, Danielle Lucero, Natasha Maddox, T. Oosterloo, D. J. Pisano, M. Verheijen, Christopher A. Hales, Aeree Chung, Richard Dodson, K. Golap, J. Gross, Patricia Henning, J. Hibbard, Yara L. Jaffé, J. D. Meyer, Martin Meyer, Monica Sanchez-Barrantes, D. Schiminovich, A. Wicenec, E. Wilcots, M. Bershady, N. Scoville, Jay Strader, E. Tremou, Ricardo Salinas, R. Chávez

引用次数: 0