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您的检索式：作者名="Mihalis Mathioudakis"
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| 1 | Multi-wavelength observations of the 2014 June 11 M3.9 flare: temporal and spatial characteristics显示文摘We present multi-wavelength observations of an M-class flare(M3.9) that occurred on 2014 June 11.Our observations were conducted with the Dunn Solar Telescope(DST),employing adaptive optics,the multi-camera system Rapid Oscillations in Solar Atmosphere(ROSA),the new Hydrogen-Alpha Rapid Dynamics camera(HARDcam) in various wavelengths,such as Ca II K,Mg I b2(at 5172.7 A),and Hα narrow band and G-band continuum filters.Images were re-constructed using the Kiepenheuer-Institut Speckle Interferometry Package(KISIP) code,to improve our image resolution.We observed intensity increases of ≈120%–150% in the Mg,Ca K and Hα narrow band filters during the flare.Intensity increases for the flare observed in the SDO EUV channels were several times larger,and the X-rays,as recorded by GOES,increased over a factor of 30 for the harder band.Only a modest delay was found between the onset of flare ribbons of a nearby sympathetic flare and the main flare ribbons observed in these narrow band filters.The peak flare emission occurred within a few seconds for the Ca K,Mg and Hα bands.Timedistance techniques indicate propagation velocities of ≈60 km s^-1 for the main flare ribbon and as high as300 km s^-1 for smaller regions,which we attribute to filament eruptions.This result and delays and velocities observed with SDO(≈100 km s^-1) for different coronal heights agree well with the simple model of energy propagation versus height,although a more detailed model for the flaring solar atmosphere is needed.Finally,we detected marginal quasi-periodic pulsations(QPPs) in the 40–60 s range for the Ca K,Mg and Hα bands,and such measurements are important for disentangling the detailed flare-physics. | Damian J.Christian David Kuridze David B.Jess Menoa Yousefi Mihalis Mathioudakis | 2019 | Research in Astronomy and Astrophysics2019，19，7： | 0 |
| 2 | Can active late-type stars contribute to the Galactic lithium abundance?显示文摘Lithium abundances in our Galaxy and especially 6 Li abundances provide important constraints on our understanding of Big Bang Nucleosynthesis(BBNS),stellar evolution and the creation of light elements by cosmic rays in the ISM.~6 Li has been detected in energetic solar events,one chromospherically active binary and several dwarf halo stars.Continuing our work on active late-type stars with high lithium abundances,we expand our study to consider if the flare origin of lithium created by spallation can contribute significantly to the Galactic abundance of lithium.We previously derived ~6 Li/~7 Li=0.030 ± 0.010 for active K dwarf GJ 117 using VLT UVES observations.We find^6 Li/~7 Li ratios of 0.02 and 0.10 for two other stars in our sample,GJ 182 and EUVE J1145-55.3 A,respectively.Considering that these later type,active stars have significant flare rates and stellar winds,we have estimated the contribution of these stars to the Galactic lithium abundance.Given that K and M stars comprise over 84% of our Galaxy and that many of these can have significant stellar winds,we conclude that spallation in stellar flares can contribute 1% and up to 5% of the Galactic lithium abundance. | Darnell E.Kelly Damian J.Christian Mihalis Mathioudakis Darko Jevremovi′c | 2020 | Research in Astronomy and Astrophysics2020，20，7： | 0 |
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