scholarly journals A statistical study of fast magnetic reconnection in turbulent accretion disks and jets

2019 ◽  
Author(s):  
Luis H.S. Kadowaki ◽  
Elisabete De Gouveia Dal Pino ◽  
Tania E. Medina-Torrejon
Keyword(s):  
Magnetic Reconnection ◽  
Accretion Disks ◽  
Statistical Study

Statistical study of magnetic reconnection in accretion disks systems around HMXBs

2018 ◽  
Vol 14 (S346) ◽  
pp. 273-276
Author(s):  
Luís H.S. Kadowaki ◽  
Elisabete M. de Gouveia Dal Pino ◽  
James M. Stone
Keyword(s):  
Magnetic Reconnection ◽  
Accretion Disks ◽  
Thermal Emission ◽  
High Mass ◽  
Potential Mechanism ◽  
Mhd Instabilities ◽  
General Relativistic ◽  
X Ray Binaries ◽  
Coronal Region ◽  
Fast Reconnection

AbstractHighly magnetized accretion disks are present in high-mass X-ray binaries (HMXBs). A potential mechanism to explain the transition between the High/Soft and Low/Hard states observed in HMXBs can be attributed to fast magnetic reconnection induced in the turbulent corona. In this work, we present results of global general relativistic MHD (GRMHD) simulations of accretion disks around black holes that show that fast reconnection events can naturally arise in the coronal region of these systems in presence of turbulence triggered by MHD instabilities, indicating that such events can be a potential mechanism to explain the transient non-thermal emission in HMXBs. To find the zones of fast reconnection, we have employed an algorithm to identify the presence of current sheets in the turbulent regions and computed statistically the magnetic reconnection rates in these locations obtaining average reconnection rates consistent with the predictions of the theory of turbulence-induced fast reconnection.

scholarly journals Statistical study of magnetic cloud erosion by magnetic reconnection

2015 ◽  
Vol 120 (1) ◽  
pp. 43-60 ◽  
Author(s):  
A. Ruffenach ◽  
B. Lavraud ◽  
C. J. Farrugia ◽  
P. Démoulin ◽  
S. Dasso ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Statistical Study ◽  
Magnetic Cloud

scholarly journals MHD Instabilities in Accretion Disks and Their Implications in Driving Fast Magnetic Reconnection

2018 ◽  
Vol 864 (1) ◽  
pp. 52 ◽  
Author(s):  
Luis H. S. Kadowaki ◽  
Elisabete M. De Gouveia Dal Pino ◽  
James M. Stone
Keyword(s):  
Magnetic Reconnection ◽  
Accretion Disks ◽  
Mhd Instabilities

scholarly journals Statistical Study of Solar White-light Flares and Comparison with Superflares on Solar-type Stars

2018 ◽  
Vol 13 (S340) ◽  
pp. 221-224
Author(s):  
Kosuke Namekata ◽  
Takahito Sakaue ◽  
Kyoko Watanabe ◽  
Ayumi Asai ◽  
Hiroyuki Maehara ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
White Light ◽  
Decay Time ◽  
Solar Flares ◽  
Statistical Study ◽  
Scaling Law ◽  
Statistical Research ◽  
Solar Type

AbstractRecently, many superflares on solar-type stars were discovered as white-light flares (WLFs). A correlation between the energies (E) and durations (t) of superflares is derived as t∝E0.39, and this can be theoretically explained by magnetic reconnection (t∝E1/3). In this study, we carried out a statistical research on 50 solar WLFs with SDO/HMI to examine the t-E relation. As a result, the t-E relation on solar WLFs (t∝E0.38) is quite similar stellar superflares, but the durations of stellar superflares are much shorter than those extrapolated from solar WLFs. We present the following two interpretations; (1) in solar flares, the cooling timescale of WL emission may be longer than the reconnection one, and the decay time can be determined by the cooling timescale; (2) the distribution can be understood by applying a scaling law t∝E1/3B−5/3 derived from the magnetic reconnection theory.

Statistical Study of the Rotation Effect of Am Stars

1976 ◽  
Vol 32 ◽  
pp. 675-683
Author(s):  
Keiichi Kodaira
Keyword(s):  
Statistical Study ◽  
Rotation Velocity ◽  
General View ◽  
Slow Rotation ◽  
Rotation Effect

SummaryExcess of [m1] index of Am stars, relative to normal stars, is statistically found to be correlated with rotation velocity; the coefficient is estimated at ∆׀m1׀ /∆V(km/sec) ˜ - 0.0007 among Am stars. This result supports the general view that slow rotation is essential for Am phenomena.

A large rotating structure around AB Doradus A at VLBI scale

2019 ◽  
Vol 15 (S354) ◽  
pp. 189-194
Author(s):  
J. B. Climent ◽  
J. C. Guirado ◽  
R. Azulay ◽  
J. M. Marcaide
Keyword(s):  
Magnetic Reconnection ◽  
Main Sequence ◽  
Complex Structure ◽  
Main Sequence Star ◽  
Polar Cap ◽  
Vlbi Observations ◽  
Rotating Structure ◽  
Source Structure ◽  
Expected Position

AbstractWe report the results of three VLBI observations of the pre-main-sequence star AB Doradus A at 8.4 GHz. With almost three years between consecutive observations, we found a complex structure at the expected position of this star for all epochs. Maps at epochs 2007 and 2010 show a double core-halo morphology while the 2013 map reveals three emission peaks with separations between 5 and 18 stellar radii. Furthermore, all maps show a clear variation of the source structure within the observing time. We consider a number of hypothesis in order to explain such observations, mainly: magnetic reconnection in loops on the polar cap, a more general loop scenario and a close companion to AB Dor A.

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