Deriving the radial distances of wide coronal mass ejections from elongation measurements in the heliosphere - application to CME-CME interaction

By N. Lugaz, A. Vourlidas, Ilia I. Roussev. 2009

161 citations recorded by the source corpus.

Abstract. We present general considerations regarding the derivation of the radial distances of coronal mass ejections (CMEs) from elongation angle measurements such as those provided by SECCHI and SMEI, focusing on measurements in the Heliospheric Imager 2 (HI-2) field of view (i.e. past 0.3 AU). This study is based on a three-dimensional (3-D) magneto-hydrodynamics (MHD) simulation of two CMEs observed by SECCHI on 24–27 January 2007. Having a 3-D simulation with synthetic HI images, we are able to compare the two basic methods used to derive CME positions from elongation angles, the so-called "Point-P" and "Fixed-φ" approximations. We confirm, following similar works, that both methods, while valid in the most inner heliosphere, yield increasingly large errors in HI-2 field of view for fast and wide CMEs. Using a simple model of a CME as an expanding self-similar sphere, we derive an analytical relationship between elongation angles and radial distances for wide CMEs. This relationship is simply the harmonic mean of the "Point-P" and "Fixed-φ" approximations and it is aimed at complementing 3-D fitting of CMEs by cone models or flux rope shapes. It proves better at getting the kinematics of the simulated CME right when we compare the results of our line-of-sights to the MHD simulation. Based on this approximation, we re-analyze the J-maps (time-elongation maps) in 26–27 January 2007 and present the first observational evidence that the merging of CMEs is associated with a momentum exchange from the faster ejection to the slower one due to the propagation of the shock wave associated with the fast eruption through the slow eruption.

Subfields: Astronomy and Astrophysics, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/8732509c6edf44fa8afc8e09f47643dab939385a

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In Astronomy and Astrophysics

1. M. Temmer
2. N. Lugaz
3. J. Davies
4. A. Thernisien
5. C. Farrugia
6. Jan Luhmann
7. A. Vourlidas
8. Ilia I. Roussev

In Molecular Biology

1. A. Thernisien
2. N. Lugaz
3. M. Temmer
4. J. Davies
5. C. Farrugia
6. A. Vourlidas
7. Ilia I. Roussev
8. Jan Luhmann

Citations in the corpus

• Propagation of Interplanetary Coronal Mass Ejections: The Drag-Based Model (2013, unknown): “(2009), Lynch et al. (2010), and Wood, Howard, and Socker (2010).”
• THE DEFLECTION OF THE TWO INTERACTING CORONAL MASS EJECTIONS OF 2010 MAY 23–24 AS REVEALED BY COMBINED IN SITU MEASUREMENTS AND HELIOSPHERIC IMAGING (2012, methodology): “This event has been fully analyzed in a number of articles, using STEREO and SMEI data (Harrison et al. 2009; Webb et al. 2009; Lugaz et al. 2009a) as well as numerical simulations (Lugaz et al. 2008b, 2009b; Odstrcil & Pizzo 2009).”
• GEOMETRIC TRIANGULATION OF IMAGING OBSERVATIONS TO TRACK CORONAL MASS EJECTIONS CONTINUOUSLY OUT TO 1 AU (2010, background): “Projection and Thomson-scattering effects may affect the tracks in the timeelongation maps in ways that are difficult to assess quantitatively without detailed modeling of the coronal brightness (Vourlidas & Howard 2006; Lugaz et al. 2008, 2009).”
• CONNECTING SPEEDS, DIRECTIONS AND ARRIVAL TIMES OF 22 CORONAL MASS EJECTIONS FROM THE SUN TO 1 AU (2014, methodology): “Even numerical simulations have been employed to enhance our ability to derive the physics of solar wind structures from heliospheric imaging (e.g. Lugaz et al. 2009, 2011; Xiong et al. 2013a,b; Rollett et al. 2013).”
• ON SUN-TO-EARTH PROPAGATION OF CORONAL MASS EJECTIONS (2013, background): “This late acceleration results from the Fβ assumption of CME geometry and is not physically meaningful (see furtherdiscussions in Lugaz et al. 2009; Wood et al. 2009; Liu et al. 2013).”
• The Interaction of Successive Coronal Mass Ejections: A Review (2016, background): “As discussed in Lugaz, Manchester, and Gombosi (2005) and further in Lugaz, Vourlidas, and Roussev (2009), when the trailing shock impacts the leading SOLA: Review_v4.tex; 16 March 2017; 5:40; p. 21 magnetic ejecta, the dense sheath behind the shock must remain between the two magnetic ejecta, even…”
• RECONSTRUCTING CORONAL MASS EJECTIONS WITH COORDINATED IMAGING AND IN SITU OBSERVATIONS: GLOBAL STRUCTURE, KINEMATICS, AND IMPLICATIONS FOR SPACE WEATHER FORECASTING (2010, methodology): “Harmonic Mean Given the restrictions of the PP and Fβ approximations, a compromise would be to take the harmonic mean (HM) of these two formulas (Lugaz et al. 2009), namely, 1 rHM = 1 2 ( 1 rPP + 1 rFφ ) , which gives rHM = 2d sinα 1 + sin(α + β) .”