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New Results on Stellar Flares Monitored with MAXI/GSC

New Results on Stellar Flares Monitored with MAXI/GSC. Yohko Tsuboi , Kyohei Yamazaki, Akiko Uzawa, Takanori Matsumura (Chuo Univ.), Satoshi Nakahira (Aoyama Gakuin Univ.), Motoki Nakajima (Nihon Univ.), and the MAXI team. Stars detected with MAXI/GSC. Flare. Eta Carinae. T Tauri star.

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New Results on Stellar Flares Monitored with MAXI/GSC

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  1. New Results on Stellar Flares Monitored with MAXI/GSC Yohko Tsuboi, Kyohei Yamazaki, Akiko Uzawa, Takanori Matsumura (Chuo Univ.), Satoshi Nakahira (Aoyama Gakuin Univ.), Motoki Nakajima (Nihon Univ.), and the MAXI team

  2. Stars detected with MAXI/GSC Flare Eta Carinae T Tauri star Massive stellar binary : 2 Low-mass star : 8 Single T Tauri star : 1 RS CVn binary : 7 theta Ori C RS CVn stars

  3. T Tauri star TWA-7 • fast rotator • deep convection zone V=19.2 km s-1 (cf. Vsun=0.6 km s-1) TWA-7

  4. X-ray variability of TWA-7 Phase 2 Phase 0 Phase 1 td < 8 [ks]

  5. Spectrum of TWA-7 flare Lx = 1.2+0.3 ×1033 [erg s-1] cf. Lx_sun =1027[erg s-1] -0.4 One of the brightest flare in those on T Tauri stars log EM [cm-3] = 55.98 Lx [erg s-1] = 1.2 ×1033 (2-20keV , The error fixes kT. ) log EM [cm-3] = 55.98 Lx [erg s-1] = 1.2 ×1033 (2-20keV , The error fixes kT. ) log EM [cm-3] = 55.98 Lx [erg s-1] = 1.2 ×1033 (2-20keV , The error fixes kT. ) log EM [cm-3] = 55.98 Lx [erg s-1] = 1.2 ×1033 (2-20keV , The error fixes kT. ) log EM [cm-3] = 55.98 Lx [erg s-1] = 1.2 ×1033 (2-20keV , The error fixes kT. ) log EM [cm-3] = 55.98 Lx [erg s-1] = 1.2 ×1033 (2-20keV , The error fixes kT. ) +0.3 –0.4

  6. RS CVn type stars • close detached binaries • tidally locked • fast rotators deep convection zone

  7. Flares from RS CVn stars • 14 flares from 7 RS CVn binaries • 2 biggest flares in all the stellar flares Lx = 5+4 ×1033 erg s-1 Lx = 4+1 ×1033 erg s-1 -2 - II Peg GT Mus

  8. Flare frequency Flares come from specific stars Then which component is special? Interaction between each component is special? Poisson distribution (the expectation value is the same as that of the data)

  9. Spin velocity vs flares MAXI detected MAXI non detected Spin velocity [km s-1] Spin velocity [km s-1] Probability that two datasets differ significantly 21% 44% 69% (not weighted) 97% (flare freq. weighted)

  10. Radius vs flares MAXI detected MAXI non detected Radius [solar radius] Radius [solar radius] Probability that two datasets differ significantly 96% (not weighted) 99.8% (flare freq. weighted) 10% 74%

  11. Binary parameters vs flares MAXI detected MAXI non detected Separation [solar radius] Orbital period [day] 51% (not weighted) 86% (flare freq. weighted) 11% 73% Probability that two datasets differ significantly

  12. Summary • We increased the big flare samples (14 flares from 7 RS Cvns, 1 flare from 1 T Tauri star) • 2 biggest flares : II Peg : GT Mus: Lx = 4+-1 erg s-1 • Hint for “Main big flare maker is subgiantcomponent”  2, 3 years are needed to conclude Lx = 5+4 erg s-1 -2

  13. TWA-7 RS CVn stars Vcool=10-100 km s-1 V=19.2 km s-1

  14. Only spin velocity and the depth of the convection zone are keys to originate big flares?

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