arXiv - PHYS - Solar and Stellar Astrophysics最新文献_第7页

3D Radiation-Hydrodynamical Simulations of Shadows on Transition Disks 过渡盘阴影的三维辐射流体力学模拟

arXiv - PHYS - Solar and Stellar Astrophysics Pub Date : 2024-09-12 DOI: arxiv-2409.08373

Shangjia Zhang, Zhaohuan Zhu

{"title":"3D Radiation-Hydrodynamical Simulations of Shadows on Transition Disks","authors":"Shangjia Zhang, Zhaohuan Zhu","doi":"arxiv-2409.08373","DOIUrl":"https://doi.org/arxiv-2409.08373","url":null,"abstract":"Shadows are often observed in transition disks, which can result from\u0000obscuring by materials closer to the star, such as a misaligned inner disk.\u0000While shadows leave apparent darkened emission as observational signatures,\u0000they have significant dynamical impact on the disk. We carry out 3D radiation\u0000hydrodynamical simulations to study shadows in transition disks and find that\u0000the temperature drop due to the shadow acts as an asymmetric driving force,\u0000leading to spirals in the cavity. These spirals have zero pattern speed\u0000following the fixed shadow. The pitch angle is given by\u0000tan$^{-1}$($c_s$/$v_phi$) (6$^{circ}$ if $h/r$=0.1). These spirals transport\u0000mass through the cavity efficiently, with $alpha sim 10^{-2}$ in our\u0000simulation. Besides spirals, the cavity edge can also form vortices and\u0000flocculent streamers. When present, these features could disturb the\u0000shadow-induced spirals. By carrying out Monte Carlo Radiative Transfer\u0000simulations, we show that these features resemble those observed in\u0000near-infrared scattered light images. In the vertical direction, the vertical\u0000gravity is no longer balanced by the pressure gradient alone. Instead, an\u0000azimuthal convective acceleration term balances the gravity-pressure\u0000difference, leading to azimuthally periodic upward and downward gas motion\u0000reaching 10% of the sound speed, which can be probed by ALMA line observations.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258085","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 Model for Flux Rope Formation and Disconnection in Pseudostreamer Coronal Mass Ejections 伪流子日冕物质抛射中的通量绳索形成和断开模型

arXiv - PHYS - Solar and Stellar Astrophysics Pub Date : 2024-09-12 DOI: arxiv-2409.08126

P. F. Wyper, B. J. Lynch, C. R. DeVore, P. Kumar, S. K. Antiochos, L. K. S. Daldorff

{"title":"A Model for Flux Rope Formation and Disconnection in Pseudostreamer Coronal Mass Ejections","authors":"P. F. Wyper, B. J. Lynch, C. R. DeVore, P. Kumar, S. K. Antiochos, L. K. S. Daldorff","doi":"arxiv-2409.08126","DOIUrl":"https://doi.org/arxiv-2409.08126","url":null,"abstract":"Coronal mass ejections (CMEs) from pseudostreamers represent a significant\u0000fraction of large-scale eruptions from the Sun. In some cases, these CMEs take\u0000a narrow jet-like form reminiscent of coronal jets; in others, they have a much\u0000broader fan-shaped morphology like CMEs from helmet streamers. We present\u0000results from a magnetohydrodynamic simulation of a broad pseudostreamer CME.\u0000The early evolution of the eruption is initiated through a combination of\u0000breakout interchange reconnection at the overlying null point and ideal\u0000instability of the flux rope that forms within the pseudostreamer. This stage\u0000is characterised by a rolling motion and deflection of the flux rope toward the\u0000breakout current layer. The stretching out of the strapping field forms a flare\u0000current sheet below the flux rope; reconnection onset there forms low-lying\u0000flare arcade loops and the two-ribbon flare footprint. Once the CME flux rope\u0000breaches the rising breakout current layer, interchange reconnection with the\u0000external open field disconnects one leg from the Sun. This induces a whip-like\u0000rotation of the flux rope, generating the unstructured fan shape characteristic\u0000of pseudostreamer CMEs. Interchange reconnection behind the CME releases\u0000torsional Alfv'en waves and bursty dense outflows into the solar wind. Our\u0000results demonstrate that pseudostreamer CMEs follow the same overall magnetic\u0000evolution as coronal jets, although they present different morphologies of\u0000their ejecta. We conclude that pseudostreamer CMEs should be considered a class\u0000of eruptions that are distinct from helmet-streamer CMEs, in agreement with\u0000previous observational studies.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227213","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

Magnetic Field Evolution of the Solar Active Region 13664 太阳活动区 13664 的磁场演变

arXiv - PHYS - Solar and Stellar Astrophysics Pub Date : 2024-09-12 DOI: arxiv-2409.08124

Robert Jarolim, Astrid Veronig, Stefan Purkhart, Peijin Zhang, Matthias Rempel

{"title":"Magnetic Field Evolution of the Solar Active Region 13664","authors":"Robert Jarolim, Astrid Veronig, Stefan Purkhart, Peijin Zhang, Matthias Rempel","doi":"arxiv-2409.08124","DOIUrl":"https://doi.org/arxiv-2409.08124","url":null,"abstract":"On 2024 May 10/11, the strongest geomagnetic storm since November 2003 has\u0000occurred, with a peak Dst index of -412 nT. The storm was caused by NOAA Active\u0000Region (AR) 13664, which was the source of a large number of coronal mass\u0000ejections and flares, including 12 X-class flares. Starting from about May 7,\u0000AR 13664 showed a steep increase in its size and (free) magnetic energy, along\u0000with increased flare activity. In this study, we perform 3D magnetic field\u0000extrapolations with the NF2 nonlinear-force free code based on physics informed\u0000neural networks (Jarolim et al. 2023). In addition, we introduce the\u0000computation of the vector potential to achieve divergence-free solutions. We\u0000extrapolate vector magnetograms from SDO/HMI at the full 12 minute cadence from\u00002024 May 5-00:00 to 11-04:36 UT, in order to understand the active regions\u0000magnetic evolution and the large eruptions it produced. The computed change in\u0000magnetic energy and free magnetic energy shows a clear correspondence to the\u0000flaring activity. Regions of free magnetic energy and depleted magnetic energy\u0000indicate the flare origin and are in good correspondence with observations in\u0000Extreme Ultraviolet. Our results suggest that the modeled solar flares are\u0000related to significant topological reconfigurations. We provide a detailed\u0000analysis of the X4.0-class flare on May 10, where we show that the interaction\u0000between separated magnetic domains is directly linked to major flaring events.\u0000With this study, we provide a comprehensive data set of the magnetic evolution\u0000of AR 13664 and make it publicly available for further analysis.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227214","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

Super-slowly rotating Ap (ssrAp) stars: Spectroscopic study 超慢旋转Ap（ssrAp）星：光谱研究

arXiv - PHYS - Solar and Stellar Astrophysics Pub Date : 2024-09-12 DOI: arxiv-2409.08060

G. Mathys, D. L. Holdsworth, M. Giarrusso, D. W. Kurtz, G. Catanzaro, F. Leone

{"title":"Super-slowly rotating Ap (ssrAp) stars: Spectroscopic study","authors":"G. Mathys, D. L. Holdsworth, M. Giarrusso, D. W. Kurtz, G. Catanzaro, F. Leone","doi":"arxiv-2409.08060","DOIUrl":"https://doi.org/arxiv-2409.08060","url":null,"abstract":"To gain better understanding of the Ap stars with the longest rotation\u0000periods, we obtained high resolution spectra of a sample of super-slowly\u0000rotating Ap (ssrAp) star candidates identified by a TESS photometric survey, to\u0000confirm that they are indeed Ap stars, to check that their v sin i values are\u0000compatible with super-slow rotation, and to obtain a first estimate of their\u0000magnetic field strengths. We determined whenever possible their mean magnetic\u0000field modulus, their mean quadratic magnetic field, and an upper limit of their\u0000projected equatorial velocities. Eighteen of the 27 stars studied are typical\u0000Ap stars; most of the other nine appear to be misclassified. One of the Ap\u0000stars is not a slow rotator; it must be seen nearly pole-on. The properties of\u0000the remaining 17 are compatible with moderately to extremely long rotation\u0000periods. Eight new stars with resolved magnetically split lines in the visible\u0000range were discovered; their mean magnetic field modulus and their mean\u0000quadratic magnetic field were measured. The mean quadratic field could also be\u0000determined in five more stars. Five new spectroscopic binaries containing an Ap\u0000star were identified. Among the misclassified stars, one SB2 system with two\u0000similar, sharp-lined Am components was also discovered. The technique that we\u0000used to carry out a search for ssrAp star candidates using TESS data is\u0000validated, but appears limited by uncertainties in the spectral classification\u0000of Ap stars. The new magnetic field measurements obtained as part of this study\u0000lend further support to the tentative conclusions of our previous studies: the\u0000absence of periods longer than ~150 d in stars with magnetic fields stronger\u0000than ~7.5 kG, the lower rate of occurrence of super-slow rotation for field\u0000strengths less than ~2 kG than in the range ~3-7.5 kG, and the deficiency of\u0000slowly rotating Ap stars with field strengths between ~2 and ~3 kG.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217290","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

The Atacama Cosmology Telescope: Systematic Transient Search of Single Observation Maps 阿塔卡马宇宙学望远镜：单一观测图的系统瞬变搜索

arXiv - PHYS - Solar and Stellar Astrophysics Pub Date : 2024-09-12 DOI: arxiv-2409.08429

Emily K. Biermann, Yaqiong Li, Sigurd Naess, Steve K. Choi, Susan E. Clark, Mark Devlin, Jo Dunkley, P. A. Gallardo, Yilun Guan, Allen Foster, Matthew Hasselfield, Carlos Hervías-Caimapo, Matt Hilton, Adam D. Hincks, Anna Y. Q. Ho, John C. Hood II, Kevin M. Huffenberger, Arthur Kosowsky, Michael D. Niemack, John Orlowski-Scherer, Lyman Page, Bruce Partridge, Maria Salatino, Cristóbal Sifón, Suzanne T. Staggs, Cristian Vargas, Edward J. Wollack

{"title":"The Atacama Cosmology Telescope: Systematic Transient Search of Single Observation Maps","authors":"Emily K. Biermann, Yaqiong Li, Sigurd Naess, Steve K. Choi, Susan E. Clark, Mark Devlin, Jo Dunkley, P. A. Gallardo, Yilun Guan, Allen Foster, Matthew Hasselfield, Carlos Hervías-Caimapo, Matt Hilton, Adam D. Hincks, Anna Y. Q. Ho, John C. Hood II, Kevin M. Huffenberger, Arthur Kosowsky, Michael D. Niemack, John Orlowski-Scherer, Lyman Page, Bruce Partridge, Maria Salatino, Cristóbal Sifón, Suzanne T. Staggs, Cristian Vargas, Edward J. Wollack","doi":"arxiv-2409.08429","DOIUrl":"https://doi.org/arxiv-2409.08429","url":null,"abstract":"We conduct a systematic search for astrophysical transients using data from\u0000the Atacama Cosmology Telescope (ACT). The data were taken from 2017 to 2022 in\u0000three frequency bands spanning 77 GHz to 277 GHz. In this paper we present a\u0000pipeline for transient detection using single observation maps where each pixel\u0000of a map contains one observation with an integration time of approximately\u0000four minutes. We find 34 transient events at 27 unique locations. All but two\u0000of the transients are associated with Galactic stars and exhibit a wide range\u0000of properties. We also detect an event coincident with the classical nova, YZ\u0000Ret and one event consistent with a flaring active galactic nucleus. We notably\u0000do not detect any reverse shock emission from gamma ray bursts, a non-detection\u0000which is in tension with current models.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258087","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

Using Neural Network Models to Estimate Stellar Ages from Lithium Equivalent Widths: An EAGLES Expansion 利用神经网络模型从锂当量宽度估算恒星年龄：EAGLES 扩展

arXiv - PHYS - Solar and Stellar Astrophysics Pub Date : 2024-09-11 DOI: arxiv-2409.07523

George Weaver, Robin D. Jeffries, Richard J. Jackson

{"title":"Using Neural Network Models to Estimate Stellar Ages from Lithium Equivalent Widths: An EAGLES Expansion","authors":"George Weaver, Robin D. Jeffries, Richard J. Jackson","doi":"arxiv-2409.07523","DOIUrl":"https://doi.org/arxiv-2409.07523","url":null,"abstract":"We present an Artificial Neural Network (ANN) model of photospheric lithium\u0000depletion in cool stars (3000 < Teff / K < 6500), producing estimates and\u0000probability distributions of age from Li I 6708A equivalent width (LiEW) and\u0000effective temperature data inputs. The model is trained on the same sample of\u00006200 stars from 52 open clusters, observed in the Gaia-ESO spectroscopic\u0000survey, and used to calibrate the previously published analytical EAGLES model,\u0000with ages 2 - 6000 Myr and -0.3 < [Fe/H] < 0.2. The additional flexibility of\u0000the ANN provides some improvements, including better modelling of the \"lithium\u0000dip\" at ages < 50 Myr and Teff ~ 3500K, and of the intrinsic dispersion in LiEW\u0000at all ages. Poor age discrimination is still an issue at ages > 1 Gyr,\u0000confirming that additional modelling flexibility is not sufficient to fully\u0000represent the LiEW - age - Teff relationship, and suggesting the involvement of\u0000further astrophysical parameters. Expansion to include such parameters -\u0000rotation, accretion, and surface gravity - is discussed, and the use of an ANN\u0000means these can be more easily included in future iterations, alongside more\u0000flexible functional forms for the LiEW dispersion. Our methods and ANN model\u0000are provided in an updated version 2.0 of the EAGLES software.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217292","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

Sun-as-a-star Analysis of the X1.6 Flare on 2023 August 5: Dynamics of Post-flare Loops in Spatially Integrated Observational Data 2023 年 8 月 5 日 X1.6 耀斑的太阳-恒星分析：空间综合观测数据中的耀斑后环流动力学

arXiv - PHYS - Solar and Stellar Astrophysics Pub Date : 2024-09-11 DOI: arxiv-2409.07630

Takato Otsu, Ayumi Asai, Kai Ikuta, Kazunari Shibata

{"title":"Sun-as-a-star Analysis of the X1.6 Flare on 2023 August 5: Dynamics of Post-flare Loops in Spatially Integrated Observational Data","authors":"Takato Otsu, Ayumi Asai, Kai Ikuta, Kazunari Shibata","doi":"arxiv-2409.07630","DOIUrl":"https://doi.org/arxiv-2409.07630","url":null,"abstract":"Post-flare loops are loop-like plasmas observed during the decay phase of\u0000solar flares, and they are expected to exist for stellar flares. However, it is\u0000unclear how post-flare loops are observed in stellar flares' cases. To clarify\u0000behaviors of post-flare loops in spatially integrated data, we performed the\u0000Sun-as-a-star analysis of the X1.6 flare that occurred on 2023 August 5, using\u0000GOES X-ray flux ($sim10^7$ K), extreme ultraviolet (EUV) images taken by\u0000Atmospheric Imaging Assembly onboard the Solar Dynamic Observatory\u0000($ge10^{4.9}$ K) and H$alpha$ data taken by Solar Dynamics Doppler Imager on\u0000board the Solar Magnetic Activity Research Telescope at Hida Observatory, Kyoto\u0000University ($sim10^4$ K). As a result, this flare showed signatures\u0000corresponding to the important dynamics of the post-flare loops even in the\u0000spatially integrated data: (1) The H$alpha$ light curve showed two distinct\u0000peaks corresponding to the flare ribbons and the post-flare loops. The plasma\u0000cooling in the post-flare loops generated different peak times in soft X-rays,\u0000EUV, and H$alpha$ light curves. (2) Downflows were confirmed as simultaneous\u0000redshifted/blueshifted absorptions in the H$alpha$ spectra. (3) The apparent\u0000rise of post-flare loops was recognized as a slowing of the decay for the\u0000H$alpha$ light curve. These results are keys to investigating stellar\u0000post-flare loops with spatially integrated data. We also discuss the dependence\u0000of our results on flare locations and their possible applications to stellar\u0000observations.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227216","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

On the dynamical evolution of Cepheid multiplicity in star clusters and its implications for B-star multiplicity at birth 关于星团中仙女座倍率的动态演变及其对 B 星诞生时倍率的影响

arXiv - PHYS - Solar and Stellar Astrophysics Pub Date : 2024-09-11 DOI: arxiv-2409.07530

František Dinnbier, Richard I. Anderson, Pavel Kroupa

{"title":"On the dynamical evolution of Cepheid multiplicity in star clusters and its implications for B-star multiplicity at birth","authors":"František Dinnbier, Richard I. Anderson, Pavel Kroupa","doi":"arxiv-2409.07530","DOIUrl":"https://doi.org/arxiv-2409.07530","url":null,"abstract":"Classical Cepheid variable stars provide a unique probe to binary evolution\u0000in intermediate-mass stars over the course of several tens to hundreds of Myr.\u0000We studied the binary and multiple properties of Cepheids, assuming that all\u0000mid-B stars form in binaries inside star clusters. The binaries were subjected\u0000both to stellar evolution and dynamical encounters with other stars in the\u0000cluster. The dynamical cluster environment results in a higher binary fraction\u0000among the Cepheids that remain in star clusters ($approx 60$%) than among the\u0000Cepheids which have escaped to the field ($approx 35$%). In clusters, the\u0000binary, triple, and multiple fraction decreases with increasing cluster mass.\u0000More massive clusters have binaries of shorter orbital periods than lower mass\u0000clusters and field Cepheids. Mergers are very common with $approx 30$% of\u0000mid-B stars not evolving to Cepheids because of the interaction with their\u0000companion. Approximately $40$ % of Cepheids have merged with their companion,\u0000and the merger event impacts stellar evolution; the age of Cepheids expected\u0000from their mass can differ from the age of their host cluster. Our models\u0000predict that one in five Cepheids is the result of a merger between stars with\u0000mass below the lower mass limit for Cepheids; in clusters, these objects occur\u0000substantially later than expected from their mass. Approximately $3$ to $5$ %\u0000of all Cepheids have a compact companion ($approx 0.15$ % of all Cepheids are\u0000accompanied by a black hole). The binary fraction derived from our simulations (42%) underestimates the\u0000observed binary Cepheid fraction by approximately a factor of 2. This suggests\u0000that the true multiplicity fraction of B-stars at birth could be substantially\u0000larger than unity and, thus, that mid-B stars may typically form in triple and\u0000higher order systems.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217375","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

Simulating stellar coronal rain and slingshot prominences 模拟恒星日冕雨和弹弓状突出物

arXiv - PHYS - Solar and Stellar Astrophysics Pub Date : 2024-09-11 DOI: arxiv-2409.07297

Simon Daley-Yates, Moira Jardine

{"title":"Simulating stellar coronal rain and slingshot prominences","authors":"Simon Daley-Yates, Moira Jardine","doi":"arxiv-2409.07297","DOIUrl":"https://doi.org/arxiv-2409.07297","url":null,"abstract":"We have numerically demonstrated that simulated cool star coronae naturally\u0000form condensations. If the star rotates slowly, with a co-rotation radius\u0000greater than the Alfv'{e}n radius (i.e. $R_{mathrm{K}} > R_{mathrm{A}}$),\u0000these condensations will form below the co-rotation radius $R_{mathrm{K}}$ and\u0000simply fall back to the stellar surface as coronal rain. If, however, the star\u0000is more rapidly rotating, ($R_{mathrm{K}} < R_{mathrm{A}}$), not only rain\u0000will form but also ``slingshot prominences''. In this case, condensations\u0000collect into a large mass reservoir around the co-rotation radius, from which\u0000periodic centrifugal ejections occur. In this case, some $51%$ of the coronal\u0000mass is cold gas, either in rain or prominences. We find that 21% of the mass\u0000lost by our simulated fast rotating star is cold gas. Studies of stellar\u0000mass-loss from the hot wind do not consider this component of the wind and\u0000therefore systematically underestimate mass-loss rates of these stars.\u0000Centrifugal ejections happen periodically, between every 7.5 - 17.5 hours with\u0000masses clustering around $10^{16}$ g, These results agree well with\u0000observational statistics. Contrasting the fast and slow rotating\u0000magnetospheres, we find that there are two distinct types of solutions, high\u0000lying and low lying loops. Low lying loops only produce coronal rain whereas\u0000high lying loops produce both rain and slingshots.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217372","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

Confirming the Tidal Tails of the Young Open Cluster Blanco 1 with TESS Rotation Periods 用 TESS 旋转周期确认年轻疏散星团 Blanco 1 的潮汐尾迹

arXiv - PHYS - Solar and Stellar Astrophysics Pub Date : 2024-09-11 DOI: arxiv-2409.07550

Lizhou Sha, Andrew M. Vanderburg, Luke G. Bouma, Chelsea X. Huang

{"title":"Confirming the Tidal Tails of the Young Open Cluster Blanco 1 with TESS Rotation Periods","authors":"Lizhou Sha, Andrew M. Vanderburg, Luke G. Bouma, Chelsea X. Huang","doi":"arxiv-2409.07550","DOIUrl":"https://doi.org/arxiv-2409.07550","url":null,"abstract":"Blanco 1 is an $approx 130,mathrm{Myr}$ open cluster located 240 pc from\u0000the Sun below the Galactic plane. Recent studies have reported the existence of\u0000diffuse tidal tails extending 50-60 pc from the cluster center based on the\u0000positions and velocities measured by Gaia. To independently assess the reality\u0000and extent of this structure, we used light curves generated from TESS\u0000full-frame images to search for photometric rotation periods of stars in and\u0000around Blanco 1. We detected rotation periods down to a stellar effective\u0000temperature of $approx 3100,mathrm{K}$ in 347 of the 603 cluster member\u0000candidates for which we have light curves. For cluster members in the core and\u0000candidate members in the tidal tails, both within a temperature range of 4400\u0000to 6200 K, 74% and 72% of the rotation periods are consistent with the\u0000single-star gyrochronological sequence, respectively. In contrast, a comparison\u0000sample of field stars yielded gyrochrone-consistent rotation periods for only\u00008.5% of stars. The tidal tail candidates' overall conformance to the core\u0000members' gyrochrone sequence implies that their contamination ratio is\u0000consistent with zero and < 0.33 at the $2sigma$ level. This result confirms\u0000the existence of Blanco 1 tidal tails and doubles the number of Blanco 1\u0000members for which there are both spatio-kinematic and rotation-based cluster\u0000membership verification. Extending the strategy of using TESS light curves for\u0000gyrochronology to other nearby young open clusters and stellar associations may\u0000provide a viable strategy for mapping out their dissolution and broadening the\u0000search for young exoplanets.","PeriodicalId":501068,"journal":{"name":"arXiv - PHYS - Solar and Stellar Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217307","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