Variability of the Sun and Sun-like Stars: from Asteroseismology to Space Weather最新文献_第2页

Influence of orbital forcing and solar activity on climate change in the past 过去轨道强迫和太阳活动对气候变化的影响

Variability of the Sun and Sun-like Stars: from Asteroseismology to Space Weather Pub Date : 2018-04-01 DOI: 10.1051/978-2-7598-2196-9-015

V. Dergachev

引用次数: 0

Realistic Simulations of Stellar Radiative MHD 恒星辐射MHD的真实模拟

Variability of the Sun and Sun-like Stars: from Asteroseismology to Space Weather Pub Date : 2018-04-01 DOI: 10.1051/978-2-7598-2196-9-004

Alan A. Wary, Khalil Bensassiy, I. Kitiashvili, N. Mansour, A. Kosovichev

引用次数: 6

A brief history of the solar diameter measurements: a critical quality assessment of the existing data 太阳直径测量简史:对现有数据的关键质量评估

Variability of the Sun and Sun-like Stars: from Asteroseismology to Space Weather Pub Date : 2016-09-09 DOI: 10.1051/978-2-7598-2196-9-006

J. Rozelot, A. Kosovichev, A. Kilçik

{"title":"A brief history of the solar diameter measurements: a critical quality assessment of the existing data","authors":"J. Rozelot, A. Kosovichev, A. Kilçik","doi":"10.1051/978-2-7598-2196-9-006","DOIUrl":"https://doi.org/10.1051/978-2-7598-2196-9-006","url":null,"abstract":"The size of the diameter of the Sun has been debated for a very long time. First tackled by the Greek astronomers from a geometric point of view, an estimate, although incorrect, has been determined, not truly called into question for several centuries. The French school of astronomy, under the impetus of Mouton and Picard in the XVIIth century can be considered as a pioneer in this issue. It was followed by the German school at the end of the XIXth century whose works led to a canonical value established at 959\".63 (second of arc). A number of ground-based observations has been made in the second half of the XIXth century leading to controversial results mainly due to the difficulty to disentangle between the solar and atmospheric effects. Dedicated space measurements yield to a very faint dependence of the solar diameter with time. New studies over the entire radiation spectrum lead to a clear relationship between the solar diameter and the wavelength, reflecting the height at which the lines are formed. Thus the absolute value of the solar diameter, which is a reference for many astrophysical applications, must be stated according to the wavelength. Furthermore, notable features of the Near Sub-Surface Layer (NSSL), called the leptocline, can be established in relation to the solar limb variations, mainly through the shape asphericities coefficients. The exact relationship has not been established yet, but recent studies encourage further in-depth investigations of the solar subsurface dynamics, both observationally and by numerical MHD simulations.","PeriodicalId":412697,"journal":{"name":"Variability of the Sun and Sun-like Stars: from Asteroseismology to Space Weather","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122816431","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: 6

Local Helioseismology of Emerging Active Region: A Case Study 新兴活动区的局部日震学:一个个案研究

Variability of the Sun and Sun-like Stars: from Asteroseismology to Space Weather Pub Date : 2016-07-18 DOI: 10.1051/978-2-7598-2196-9.c003

A. Kosovichev, Junwei Zhao, Stathis Ilonidis

{"title":"Local Helioseismology of Emerging Active Region: A Case Study","authors":"A. Kosovichev, Junwei Zhao, Stathis Ilonidis","doi":"10.1051/978-2-7598-2196-9.c003","DOIUrl":"https://doi.org/10.1051/978-2-7598-2196-9.c003","url":null,"abstract":"Local helioseismology provides a unique opportunity to investigate the subsurface structure and dynamics of active regions and their effect on the large-scale flows and global circulation of the Sun. We use measurements of plasma flows in the upper convection zone, provided by the Time-Distance Helioseismology Pipeline developed for analysis of solar oscillation data obtained by Helioseismic and Magnetic Imager (HMI) on Solar Dynamics Observatory (SDO), to investigate the subsurface dynamics of emerging active region NOAA 11726. The active region emergence was detected in deep layers of the convection zone about 12 hours before the first bipolar magnetic structure appeared on the surface, and 2 days before the emergence of most of the magnetic flux. The speed of emergence determined by tracking the flow divergence with depth is about 1.4 km/s, very close to the emergence speed in the deep layers. As the emerging magnetic flux becomes concentrated in sunspots local converging flows are observed beneath the forming sunspots. These flows are most prominent in the depth range 1-3 Mm, and remain converging after the formation process is completed. On the larger scale converging flows around active region appear as a diversion of the zonal shearing flows towards the active region, accompanied by formation of a large-scale vortex structure. This process occurs when a substantial amount of the magnetic flux emerged on the surface, and the converging flow pattern remains stable during the following evolution of the active region. The Carrington synoptic flow maps show that the large-scale subsurface inflows are typical for active regions. In the deeper layers (10-13 Mm) the flows become diverging, and surprisingly strong beneath some active regions. In addition, the synoptic maps reveal a complex evolving pattern of large-scale flows on the scale much larger than supergranulation.","PeriodicalId":412697,"journal":{"name":"Variability of the Sun and Sun-like Stars: from Asteroseismology to Space Weather","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132490262","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: 4

Asteroseismology with solar-like oscillations 类太阳振荡的星震学

Variability of the Sun and Sun-like Stars: from Asteroseismology to Space Weather Pub Date : 2016-02-22 DOI: 10.1051/978-2-7598-2196-9.c009

J. Christensen-Dalsgaard

引用次数: 1

Wave instabilities in an anisotropic magnetized space plasma 各向异性磁化空间等离子体中的波不稳定性

Variability of the Sun and Sun-like Stars: from Asteroseismology to Space Weather Pub Date : 2008-05-15 DOI: 10.1051/0004-6361:200809882

N. S. Dzhalilov, V. Kuznetsov, J. Staude

引用次数: 7