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Jonathan A. Constable University of St Andrews Solar REU Presentation 2009

A f lux rope model for CME initiation over solar cycle 23 . Jonathan Constable Mentors: Anthony Yeates and Piet Martens. Jonathan A. Constable University of St Andrews Solar REU Presentation 2009. A f lux rope model for CME initiation over solar cycle 23 . Contents:.

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Jonathan A. Constable University of St Andrews Solar REU Presentation 2009

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  1. A flux rope model for CME initiation over solar cycle 23 Jonathan Constable Mentors: Anthony Yeates and Piet Martens Jonathan A. Constable University of St Andrews Solar REU Presentation 2009

  2. A flux rope model for CME initiation over solar cycle 23 Contents: Motivation for the project Description of the model Choice of simulation periods SOHO (LASCO) and STEREO (SECCHI) observations Simulation results Discussion References Jonathan A. Constable University of St Andrews Solar REU Presentation 2009

  3. A flux rope model for CME initiation over solar cycle 23 1. Motivation: Approximately 11 year solar cycle over which the rate of Coronal Mass Ejections (CMEs) varies significantly; Schwabe, 1843 Hale et al,1919 Yashiro et al, 2004 b) Mackay, D. H. & van Ballegooijen, A. A., 2006; Models of the large-scale corona. I. Formation, Evolution, and liftoff of magnetic flux ropes. A.R. Yeates and D.H. Mackay 2009; Initiation of Coronal Mass Ejections in a Global Evolution Model Credit: G.L. Slater and G.A. Linford; S.L. Freeland;Yohkoh Soft X-Ray Telescope Can we extend this work to cover significant phases of solar cycle 23? Classic CME observed by the Large Angle Spectrometric Coronagraph (LASCO) C2 field of view, onboard the Solar and Heliospheric Observatory (SOHO) Jonathan A. Constable University of St Andrews Solar REU Presentation 2009

  4. A flux rope model for CME initiation over solar cycle 23 2. Description of the model: Two parts, the lower boundary at the photosphere and the corona. The lower boundary at the photosphere is evolved by the: Emergence of new magnetic flux from below the photosphere.1 Large scale flows due to differential and meridionial rotation.1 Dispersal of magnetic flux by small scale convection cell.2 Cancellation of magnetic flux at polarity inversion lines.2 The corona evolves in response to the emerging magnetic flux and the changing photospheric boundary conditions. Model inputs: We use U.S. National Solar Observatory, Kitt Peak radial synoptic magnetograms for each Carrington rotation within our simulation periods. Yeates et al, 2008 Sheeley, N. R. 2005 Jonathan A. Constable University of St Andrews Solar REU Presentation 2009

  5. A flux rope model for CME initiation over solar cycle 23 3. Choice of simulation periods: Four periods chosen: Period 1 CR1948.5 to CR1954 17th Apr 1999 – 11th Oct 1999 “Rising Phase” Period 2 CR1974.5 to CR1980 26th Mar 2001 – 19th Sept 2001 “Solar Maximum” Period 3 CR2018.5 to CR2024 8th Jul 2004 – 2nd Jan 2005 “Declining Phase” Period 4 CR2067.5 to CR2073 6th Mar 2008 – 30th Aug 2008 “Solar Minimum” Period 2 Period 1 Period 3 Stop Press! Period 5 CR1911.5 to CR1917 12th Jul 1996 – 4th Jan 1997 “Solar Minimum 22” Period 6 CR1962.5 to CR1968 3rd May 2000 – 27th Oct 2000 “Solar Maximum B” Period 4 Key: Red – CDAW 27day histogram, Blue – CACTus 27 day histogram, Grey – Monthly sunspot number Jonathan A. Constable University of St Andrews Solar REU Presentation 2009

  6. A flux rope model for CME initiation over solar cycle 23 4. SOHO (LASCO) and STEREO (SECCHI) observations: Key: Black – Histogram of 27 day CME rate Red – Monthly sunspot number Yellow – Histogram of data gap duration CDAW cycle 23 CACTus cycle 23 5° ≤ apparent width < 270° 15° ≤ apparent width < 270° 10° ≤ apparent width < 270° “Very Poor Event”, “Poor Event” and “Marginal Case” removed Legend: - CACTus observation - CDAW observation - Simulation result Jonathan A. Constable University of St Andrews Solar REU Presentation 2009

  7. A flux rope model for CME initiation over solar cycle 23 5. Simulation Results: Comparison with Yeates & Mackay 2009 • General trends consistent. • Differences could be due to the choice of newly emerging bipoles (119 Yeates et al 2009 as opposed to 117 in our simulation). Comparison with Pevtsov et al 1995 α Simulated Yeates et al 2009 Simulated random twists (-1 to 1) CR1948.5 to CR1954 (Period 1 – “Rising Phase”) xΒ = αΒ Where: Δ Jonathan A. Constable University of St Andrews Solar REU Presentation 2009

  8. A flux rope model for CME initiation over solar cycle 23 Key: Black – simulation results Red – CDAW observations Blue – CACTus observations 5. Simulation Results: Period 2 Period 1 Period 3 Period 4 Jonathan A. Constable University of St Andrews Solar REU Presentation 2009

  9. A flux rope model for CME initiation over solar cycle 23 5. Simulation Results: CDAW: Period 1 Period 2 Period 4 Period 3 Jonathan A. Constable University of St Andrews Solar REU Presentation 2009

  10. A flux rope model for CME initiation over solar cycle 23 5. Simulation Results: CACTus: Period 1 Period 2 Period 4 Period 3 Jonathan A. Constable University of St Andrews Solar REU Presentation 2009

  11. A flux rope model for CME initiation over solar cycle 23 6. Conclusions: • We were able to produce consistent results compared to Yeates & Mackay 2009 with reasonable accuracy. • Our simulations show variation over the solar cycle, with more eruptions per day at solar maximum and over a greater range of latitudes, than our simulations produced at solar minimum. • We see the 50% of observed CMEs as in Yeates & Mackay 2009, however over the solar cycle, our simulation produces only about 30% of the observed CMEs. • This could be due to: • Random bipole twists compared to a step function for twist. Less twist on average should produce fewer eruptions. We need better observations of magnetic helicity. • There are significant uncertainties in the apparent latitudes of CMEs in the observations used. Plus CACTus detects “ghost CMEs” where the supporting pylon for the occulting disk is located (-30° latitude / 120° central position angle) • The model does not easily reproduce multiple CMEs in a short timeframe. Jonathan A. Constable University of St Andrews Solar REU Presentation 2009

  12. A flux rope model for CME initiation over solar cycle 23 7. References: Hale, G. E., Ellerman, F., Nicholson, S. B., & Joy, A. H.: 1919, ApJ, 49, 153, 1919 Mackay, D. H., & van Ballegooijen, A. A.: 2006, ApJ, 641, 577 Nandy, D., Mackay, D. H., Canfield, R. C., Martens, P. C. H.: 2008, Journal of atmospheric and solar-terrestrial physics, 70, 605 Pevtsov, A. A., Canfield, R. C., Metcalf, T. R.: 1995, ApJ, 440, L109-L112 Schwabe, S. H.: 1843, Astronomische Nachrichten, 20, 495, 1843 Sheeley, N. R.: 2005, Living Rev. Solar Physics, 212, 165 van Ballegooijen, A. A., Priest, E. R., Mackay, D. H.: 2000, ApJ, 539, 983 Yashiro, S. et al: 2004, JGR, 109, A07105, doi:10.1029/2003JA010282 Yeates, A. R., Mackay, D. H., & van Ballegooijen, A. A.: 2008, Solar Physics, 247, 103 Yeates, A. R., & Mackay, D. H.: 2009, ApJ, 699, 1024 Jonathan A. Constable University of St Andrews Solar REU Presentation 2009

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